diff options
| -rw-r--r-- | ChangeLog | 2 | ||||
| -rw-r--r-- | doc/html/pcre2api.html | 9 | ||||
| -rw-r--r-- | doc/html/pcre2compat.html | 19 | ||||
| -rw-r--r-- | doc/html/pcre2pattern.html | 21 | ||||
| -rw-r--r-- | doc/html/pcre2syntax.html | 5 | ||||
| -rw-r--r-- | doc/html/pcre2test.html | 9 | ||||
| -rw-r--r-- | doc/pcre2.txt | 2971 | ||||
| -rw-r--r-- | doc/pcre2api.3 | 11 | ||||
| -rw-r--r-- | doc/pcre2compat.3 | 16 | ||||
| -rw-r--r-- | doc/pcre2pattern.3 | 22 | ||||
| -rw-r--r-- | doc/pcre2syntax.3 | 7 | ||||
| -rw-r--r-- | doc/pcre2test.1 | 11 | ||||
| -rw-r--r-- | doc/pcre2test.txt | 708 | ||||
| -rw-r--r-- | src/pcre2.h | 1 | ||||
| -rw-r--r-- | src/pcre2.h.generic | 7 | ||||
| -rw-r--r-- | src/pcre2.h.in | 1 | ||||
| -rw-r--r-- | src/pcre2_compile.c | 69 | ||||
| -rw-r--r-- | src/pcre2test.c | 16 | ||||
| -rw-r--r-- | testdata/testinput2 | 14 | ||||
| -rw-r--r-- | testdata/testoutput2 | 72 | ||||
| -rw-r--r-- | testdata/testoutput8-16-2 | 4 | ||||
| -rw-r--r-- | testdata/testoutput8-32-2 | 2 | ||||
| -rw-r--r-- | testdata/testoutput8-8-2 | 3 |
23 files changed, 2084 insertions, 1916 deletions
@@ -148,6 +148,8 @@ tests to improve coverage. (d) Avoid warning for never-use case OP_TABLE_LENGTH which is just a fudge for checking at compile time that tables are the right size. (e) Add missing "fall through" comment. + +29. Implemented PCRE2_EXTENDED_MORE and related /xx and (?xx) features. Version 10.23 14-February-2017 diff --git a/doc/html/pcre2api.html b/doc/html/pcre2api.html index a8a4638..74ef04c 100644 --- a/doc/html/pcre2api.html +++ b/doc/html/pcre2api.html @@ -1378,6 +1378,13 @@ sequence at the start of the pattern, as described in the section entitled in the <b>pcre2pattern</b> documentation. A default is defined when PCRE2 is built. <pre> + PCRE2_EXTENDED_MORE +</pre> +This option has the effect of PCRE2_EXTENDED, but, in addition, space and +horizontal tab characters are also ignored inside a character class. +PCRE2_EXTENDED_MORE is equivalent to Perl's 5.26 /xx option, and it can be +changed within a pattern by a (?xx) option setting. +<pre> PCRE2_FIRSTLINE </pre> If this option is set, an unanchored pattern is required to match before or at @@ -3344,7 +3351,7 @@ Cambridge, England. </P> <br><a name="SEC42" href="#TOC1">REVISION</a><br> <P> -Last updated: 14 April 2017 +Last updated: 17 April 2017 <br> Copyright © 1997-2017 University of Cambridge. <br> diff --git a/doc/html/pcre2compat.html b/doc/html/pcre2compat.html index df8c9d2..5c890b0 100644 --- a/doc/html/pcre2compat.html +++ b/doc/html/pcre2compat.html @@ -200,16 +200,13 @@ different way and is not Perl-compatible. (l) PCRE2 recognizes some special sequences such as (*CR) or (*NO_JIT) at the start of a pattern that set overall options that cannot be changed within the pattern. -<br> -<br> -18. The following new Perl 5.26 constructs are not yet supported in PCRE2: -<br> -<br> -(a) The Perl /a modifier restricts /d numbers to pure ascii, the new /aa -modifier restricts /i case-insensitive matching to pure ascii also, ignoring -unicode rules. This separation cannot be represented with PCRE2_UTF. -<br> -<br> +</P> +<P> +18. The Perl /a modifier restricts /d numbers to pure ascii, and the /aa +modifier restricts /i case-insensitive matching to pure ascii, ignoring Unicode +rules. This separation cannot be represented with PCRE2_UCP. +</P> +<P> 19. Perl has different limits than PCRE2. See the <a href="pcre2limit.html"><b>pcre2limit</b></a> documentation for details. Perl went with 5.10 from recursion to iteration @@ -232,7 +229,7 @@ Cambridge, England. REVISION </b><br> <P> -Last updated: 17 April 2017 +Last updated: 18 April 2017 <br> Copyright © 1997-2017 University of Cambridge. <br> diff --git a/doc/html/pcre2pattern.html b/doc/html/pcre2pattern.html index 66500c1..b8e9d73 100644 --- a/doc/html/pcre2pattern.html +++ b/doc/html/pcre2pattern.html @@ -1544,20 +1544,25 @@ alternative in the subpattern. </P> <br><a name="SEC13" href="#TOC1">INTERNAL OPTION SETTING</a><br> <P> -The settings of the PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL, and -PCRE2_EXTENDED options (which are Perl-compatible) can be changed from within -the pattern by a sequence of Perl option letters enclosed between "(?" and ")". -The option letters are +The settings of the PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL, +PCRE2_EXTENDED, and PCRE2_EXTENDED_MORE options (which are Perl-compatible) can +be changed from within the pattern by a sequence of Perl option letters +enclosed between "(?" and ")". The option letters are <pre> i for PCRE2_CASELESS m for PCRE2_MULTILINE s for PCRE2_DOTALL x for PCRE2_EXTENDED + xx for PCRE2_EXTENDED_MORE </pre> For example, (?im) sets caseless, multiline matching. It is also possible to -unset these options by preceding the letter with a hyphen, and a combined -setting and unsetting such as (?im-sx), which sets PCRE2_CASELESS and -PCRE2_MULTILINE while unsetting PCRE2_DOTALL and PCRE2_EXTENDED, is also +unset these options by preceding the letter with a hyphen. The two "extended" +options are not independent; unsetting either one cancels the effects of both +of them. +</P> +<P> +A combined setting and unsetting such as (?im-sx), which sets PCRE2_CASELESS +and PCRE2_MULTILINE while unsetting PCRE2_DOTALL and PCRE2_EXTENDED, is also permitted. If a letter appears both before and after the hyphen, the option is unset. An empty options setting "(?)" is allowed. Needless to say, it has no effect. @@ -3438,7 +3443,7 @@ Cambridge, England. </P> <br><a name="SEC30" href="#TOC1">REVISION</a><br> <P> -Last updated: 11 April 2017 +Last updated: 18 April 2017 <br> Copyright © 1997-2017 University of Cambridge. <br> diff --git a/doc/html/pcre2syntax.html b/doc/html/pcre2syntax.html index 0241002..ee58070 100644 --- a/doc/html/pcre2syntax.html +++ b/doc/html/pcre2syntax.html @@ -432,7 +432,8 @@ but some of them use Unicode properties if PCRE2_UCP is set. You can use (?m) multiline (?s) single line (dotall) (?U) default ungreedy (lazy) - (?x) extended (ignore white space) + (?x) extended: ignore white space except in classes + (?xx) as (?x) but also ignore space and tab in classes (?-...) unset option(s) </pre> The following are recognized only at the very start of a pattern or after one @@ -596,7 +597,7 @@ Cambridge, England. </P> <br><a name="SEC27" href="#TOC1">REVISION</a><br> <P> -Last updated: 31 March 2017 +Last updated: 18 April 2017 <br> Copyright © 1997-2017 University of Cambridge. <br> diff --git a/doc/html/pcre2test.html b/doc/html/pcre2test.html index 2e8a0b8..d24548d 100644 --- a/doc/html/pcre2test.html +++ b/doc/html/pcre2test.html @@ -560,9 +560,11 @@ Setting compilation options </b><br> <P> The following modifiers set options for <b>pcre2_compile()</b>. The most common -ones have single-letter abbreviations. See +ones have single-letter abbreviations, with special handling for /x (to make +it like Perl). If a second x is present, PCRE2_EXTENDED is converted into +PCRE2_EXTENDED_MORE. A third appearance adds PCRE2_EXTENDED as well. See <a href="pcre2api.html"><b>pcre2api</b></a> -for a description of their effects. +for a description of the effects of these options. <pre> allow_empty_class set PCRE2_ALLOW_EMPTY_CLASS alt_bsux set PCRE2_ALT_BSUX @@ -576,6 +578,7 @@ for a description of their effects. dupnames set PCRE2_DUPNAMES endanchored set PCRE2_ENDANCHORED /x extended set PCRE2_EXTENDED + /xx extended_more set PCRE2_EXTENDED_MORE firstline set PCRE2_FIRSTLINE match_unset_backref set PCRE2_MATCH_UNSET_BACKREF /m multiline set PCRE2_MULTILINE @@ -1807,7 +1810,7 @@ Cambridge, England. </P> <br><a name="SEC21" href="#TOC1">REVISION</a><br> <P> -Last updated: 11 April 2017 +Last updated: 17 April 2017 <br> Copyright © 1997-2017 University of Cambridge. <br> diff --git a/doc/pcre2.txt b/doc/pcre2.txt index 04bb9ca..4998a29 100644 --- a/doc/pcre2.txt +++ b/doc/pcre2.txt @@ -1396,226 +1396,233 @@ COMPILING A PATTERN tion entitled "Newline conventions" in the pcre2pattern documentation. A default is defined when PCRE2 is built. + PCRE2_EXTENDED_MORE + + This option has the effect of PCRE2_EXTENDED, but, in addition, space + and horizontal tab characters are also ignored inside a character + class. PCRE2_EXTENDED_MORE is equivalent to Perl's 5.26 /xx option, + and it can be changed within a pattern by a (?xx) option setting. + PCRE2_FIRSTLINE - If this option is set, an unanchored pattern is required to match - before or at the first newline in the subject string, though the - matched text may continue over the newline. See also PCRE2_USE_OFF- - SET_LIMIT, which provides a more general limiting facility. If - PCRE2_FIRSTLINE is set with an offset limit, a match must occur in the - first line and also within the offset limit. In other words, whichever + If this option is set, an unanchored pattern is required to match + before or at the first newline in the subject string, though the + matched text may continue over the newline. See also PCRE2_USE_OFF- + SET_LIMIT, which provides a more general limiting facility. If + PCRE2_FIRSTLINE is set with an offset limit, a match must occur in the + first line and also within the offset limit. In other words, whichever limit comes first is used. PCRE2_MATCH_UNSET_BACKREF - If this option is set, a back reference to an unset subpattern group - matches an empty string (by default this causes the current matching - alternative to fail). A pattern such as (\1)(a) succeeds when this - option is set (assuming it can find an "a" in the subject), whereas it - fails by default, for Perl compatibility. Setting this option makes + If this option is set, a back reference to an unset subpattern group + matches an empty string (by default this causes the current matching + alternative to fail). A pattern such as (\1)(a) succeeds when this + option is set (assuming it can find an "a" in the subject), whereas it + fails by default, for Perl compatibility. Setting this option makes PCRE2 behave more like ECMAscript (aka JavaScript). PCRE2_MULTILINE - By default, for the purposes of matching "start of line" and "end of - line", PCRE2 treats the subject string as consisting of a single line - of characters, even if it actually contains newlines. The "start of - line" metacharacter (^) matches only at the start of the string, and - the "end of line" metacharacter ($) matches only at the end of the + By default, for the purposes of matching "start of line" and "end of + line", PCRE2 treats the subject string as consisting of a single line + of characters, even if it actually contains newlines. The "start of + line" metacharacter (^) matches only at the start of the string, and + the "end of line" metacharacter ($) matches only at the end of the string, or before a terminating newline (except when PCRE2_DOL- - LAR_ENDONLY is set). Note, however, that unless PCRE2_DOTALL is set, + LAR_ENDONLY is set). Note, however, that unless PCRE2_DOTALL is set, the "any character" metacharacter (.) does not match at a newline. This behaviour (for ^, $, and dot) is the same as Perl. - When PCRE2_MULTILINE it is set, the "start of line" and "end of line" - constructs match immediately following or immediately before internal - newlines in the subject string, respectively, as well as at the very - start and end. This is equivalent to Perl's /m option, and it can be + When PCRE2_MULTILINE it is set, the "start of line" and "end of line" + constructs match immediately following or immediately before internal + newlines in the subject string, respectively, as well as at the very + start and end. This is equivalent to Perl's /m option, and it can be changed within a pattern by a (?m) option setting. Note that the "start of line" metacharacter does not match after a newline at the end of the - subject, for compatibility with Perl. However, you can change this by - setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a - subject string, or no occurrences of ^ or $ in a pattern, setting + subject, for compatibility with Perl. However, you can change this by + setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a + subject string, or no occurrences of ^ or $ in a pattern, setting PCRE2_MULTILINE has no effect. PCRE2_NEVER_BACKSLASH_C - This option locks out the use of \C in the pattern that is being com- - piled. This escape can cause unpredictable behaviour in UTF-8 or - UTF-16 modes, because it may leave the current matching point in the - middle of a multi-code-unit character. This option may be useful in - applications that process patterns from external sources. Note that + This option locks out the use of \C in the pattern that is being com- + piled. This escape can cause unpredictable behaviour in UTF-8 or + UTF-16 modes, because it may leave the current matching point in the + middle of a multi-code-unit character. This option may be useful in + applications that process patterns from external sources. Note that there is also a build-time option that permanently locks out the use of \C. PCRE2_NEVER_UCP - This option locks out the use of Unicode properties for handling \B, + This option locks out the use of Unicode properties for handling \B, \b, \D, \d, \S, \s, \W, \w, and some of the POSIX character classes, as - described for the PCRE2_UCP option below. In particular, it prevents - the creator of the pattern from enabling this facility by starting the - pattern with (*UCP). This option may be useful in applications that + described for the PCRE2_UCP option below. In particular, it prevents + the creator of the pattern from enabling this facility by starting the + pattern with (*UCP). This option may be useful in applications that process patterns from external sources. The option combination PCRE_UCP and PCRE_NEVER_UCP causes an error. PCRE2_NEVER_UTF - This option locks out interpretation of the pattern as UTF-8, UTF-16, + This option locks out interpretation of the pattern as UTF-8, UTF-16, or UTF-32, depending on which library is in use. In particular, it pre- - vents the creator of the pattern from switching to UTF interpretation - by starting the pattern with (*UTF). This option may be useful in - applications that process patterns from external sources. The combina- + vents the creator of the pattern from switching to UTF interpretation + by starting the pattern with (*UTF). This option may be useful in + applications that process patterns from external sources. The combina- tion of PCRE2_UTF and PCRE2_NEVER_UTF causes an error. PCRE2_NO_AUTO_CAPTURE If this option is set, it disables the use of numbered capturing paren- - theses in the pattern. Any opening parenthesis that is not followed by - ? behaves as if it were followed by ?: but named parentheses can still - be used for capturing (and they acquire numbers in the usual way). - There is no equivalent of this option in Perl. Note that, if this - option is set, references to capturing groups (back references or - recursion/subroutine calls) may only refer to named groups, though the + theses in the pattern. Any opening parenthesis that is not followed by + ? behaves as if it were followed by ?: but named parentheses can still + be used for capturing (and they acquire numbers in the usual way). + There is no equivalent of this option in Perl. Note that, if this + option is set, references to capturing groups (back references or + recursion/subroutine calls) may only refer to named groups, though the reference can be by name or by number. PCRE2_NO_AUTO_POSSESS If this option is set, it disables "auto-possessification", which is an - optimization that, for example, turns a+b into a++b in order to avoid - backtracks into a+ that can never be successful. However, if callouts - are in use, auto-possessification means that some callouts are never + optimization that, for example, turns a+b into a++b in order to avoid + backtracks into a+ that can never be successful. However, if callouts + are in use, auto-possessification means that some callouts are never taken. You can set this option if you want the matching functions to do - a full unoptimized search and run all the callouts, but it is mainly + a full unoptimized search and run all the callouts, but it is mainly provided for testing purposes. PCRE2_NO_DOTSTAR_ANCHOR If this option is set, it disables an optimization that is applied when - .* is the first significant item in a top-level branch of a pattern, - and all the other branches also start with .* or with \A or \G or ^. - The optimization is automatically disabled for .* if it is inside an - atomic group or a capturing group that is the subject of a back refer- - ence, or if the pattern contains (*PRUNE) or (*SKIP). When the opti- - mization is not disabled, such a pattern is automatically anchored if + .* is the first significant item in a top-level branch of a pattern, + and all the other branches also start with .* or with \A or \G or ^. + The optimization is automatically disabled for .* if it is inside an + atomic group or a capturing group that is the subject of a back refer- + ence, or if the pattern contains (*PRUNE) or (*SKIP). When the opti- + mization is not disabled, such a pattern is automatically anchored if PCRE2_DOTALL is set for all the .* items and PCRE2_MULTILINE is not set - for any ^ items. Otherwise, the fact that any match must start either - at the start of the subject or following a newline is remembered. Like + for any ^ items. Otherwise, the fact that any match must start either + at the start of the subject or following a newline is remembered. Like other optimizations, this can cause callouts to be skipped. PCRE2_NO_START_OPTIMIZE - This is an option whose main effect is at matching time. It does not + This is an option whose main effect is at matching time. It does not change what pcre2_compile() generates, but it does affect the output of the JIT compiler. - There are a number of optimizations that may occur at the start of a - match, in order to speed up the process. For example, if it is known - that an unanchored match must start with a specific character, the - matching code searches the subject for that character, and fails imme- - diately if it cannot find it, without actually running the main match- - ing function. This means that a special item such as (*COMMIT) at the - start of a pattern is not considered until after a suitable starting - point for the match has been found. Also, when callouts or (*MARK) - items are in use, these "start-up" optimizations can cause them to be - skipped if the pattern is never actually used. The start-up optimiza- - tions are in effect a pre-scan of the subject that takes place before + There are a number of optimizations that may occur at the start of a + match, in order to speed up the process. For example, if it is known + that an unanchored match must start with a specific character, the + matching code searches the subject for that character, and fails imme- + diately if it cannot find it, without actually running the main match- + ing function. This means that a special item such as (*COMMIT) at the + start of a pattern is not considered until after a suitable starting + point for the match has been found. Also, when callouts or (*MARK) + items are in use, these "start-up" optimizations can cause them to be + skipped if the pattern is never actually used. The start-up optimiza- + tions are in effect a pre-scan of the subject that takes place before the pattern is run. The PCRE2_NO_START_OPTIMIZE option disables the start-up optimizations, - possibly causing performance to suffer, but ensuring that in cases - where the result is "no match", the callouts do occur, and that items + possibly causing performance to suffer, but ensuring that in cases + where the result is "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK) are considered at every possible starting position in the subject string. - Setting PCRE2_NO_START_OPTIMIZE may change the outcome of a matching + Setting PCRE2_NO_START_OPTIMIZE may change the outcome of a matching operation. Consider the pattern (*COMMIT)ABC - When this is compiled, PCRE2 records the fact that a match must start - with the character "A". Suppose the subject string is "DEFABC". The - start-up optimization scans along the subject, finds "A" and runs the - first match attempt from there. The (*COMMIT) item means that the pat- - tern must match the current starting position, which in this case, it - does. However, if the same match is run with PCRE2_NO_START_OPTIMIZE - set, the initial scan along the subject string does not happen. The - first match attempt is run starting from "D" and when this fails, - (*COMMIT) prevents any further matches being tried, so the overall + When this is compiled, PCRE2 records the fact that a match must start + with the character "A". Suppose the subject string is "DEFABC". The + start-up optimization scans along the subject, finds "A" and runs the + first match attempt from there. The (*COMMIT) item means that the pat- + tern must match the current starting position, which in this case, it + does. However, if the same match is run with PCRE2_NO_START_OPTIMIZE + set, the initial scan along the subject string does not happen. The + first match attempt is run starting from "D" and when this fails, + (*COMMIT) prevents any further matches being tried, so the overall result is "no match". There are also other start-up optimizations. For example, a minimum length for the subject may be recorded. Consider the pattern (*MARK:A)(X|Y) - The minimum length for a match is one character. If the subject is + The minimum length for a match is one character. If the subject is "ABC", there will be attempts to match "ABC", "BC", and "C". An attempt to match an empty string at the end of the subject does not take place, - because PCRE2 knows that the subject is now too short, and so the - (*MARK) is never encountered. In this case, the optimization does not + because PCRE2 knows that the subject is now too short, and so the + (*MARK) is never encountered. In this case, the optimization does not affect the overall match result, which is still "no match", but it does affect the auxiliary information that is returned. PCRE2_NO_UTF_CHECK - When PCRE2_UTF is set, the validity of the pattern as a UTF string is - automatically checked. There are discussions about the validity of - UTF-8 strings, UTF-16 strings, and UTF-32 strings in the pcre2unicode - document. If an invalid UTF sequence is found, pcre2_compile() returns + When PCRE2_UTF is set, the validity of the pattern as a UTF string is + automatically checked. There are discussions about the validity of + UTF-8 strings, UTF-16 strings, and UTF-32 strings in the pcre2unicode + document. If an invalid UTF sequence is found, pcre2_compile() returns a negative error code. If you know that your pattern is valid, and you want to skip this check - for performance reasons, you can set the PCRE2_NO_UTF_CHECK option. - When it is set, the effect of passing an invalid UTF string as a pat- - tern is undefined. It may cause your program to crash or loop. Note - that this option can also be passed to pcre2_match() and + for performance reasons, you can set the PCRE2_NO_UTF_CHECK option. + When it is set, the effect of passing an invalid UTF string as a pat- + tern is undefined. It may cause your program to crash or loop. Note + that this option can also be passed to pcre2_match() and pcre_dfa_match(), to suppress validity checking of the subject string. PCRE2_UCP This option changes the way PCRE2 processes \B, \b, \D, \d, \S, \s, \W, - \w, and some of the POSIX character classes. By default, only ASCII - characters are recognized, but if PCRE2_UCP is set, Unicode properties - are used instead to classify characters. More details are given in the + \w, and some of the POSIX character classes. By default, only ASCII + characters are recognized, but if PCRE2_UCP is set, Unicode properties + are used instead to classify characters. More details are given in the section on generic character types in the pcre2pattern page. If you set - PCRE2_UCP, matching one of the items it affects takes much longer. The - option is available only if PCRE2 has been compiled with Unicode sup- + PCRE2_UCP, matching one of the items it affects takes much longer. The + option is available only if PCRE2 has been compiled with Unicode sup- port (which is the default). PCRE2_UNGREEDY - This option inverts the "greediness" of the quantifiers so that they - are not greedy by default, but become greedy if followed by "?". It is - not compatible with Perl. It can also be set by a (?U) option setting + This option inverts the "greediness" of the quantifiers so that they + are not greedy by default, but become greedy if followed by "?". It is + not compatible with Perl. It can also be set by a (?U) option setting within the pattern. PCRE2_USE_OFFSET_LIMIT This option must be set for pcre2_compile() if pcre2_set_offset_limit() - is going to be used to set a non-default offset limit in a match con- - text for matches that use this pattern. An error is generated if an - offset limit is set without this option. For more details, see the - description of pcre2_set_offset_limit() in the section that describes + is going to be used to set a non-default offset limit in a match con- + text for matches that use this pattern. An error is generated if an + offset limit is set without this option. For more details, see the + description of pcre2_set_offset_limit() in the section that describes match contexts. See also the PCRE2_FIRSTLINE option above. PCRE2_UTF - This option causes PCRE2 to regard both the pattern and the subject - strings that are subsequently processed as strings of UTF characters - instead of single-code-unit strings. It is available when PCRE2 is - built to include Unicode support (which is the default). If Unicode - support is not available, the use of this option provokes an error. - Details of how this option changes the behaviour of PCRE2 are given in + This option causes PCRE2 to regard both the pattern and the subject + strings that are subsequently processed as strings of UTF characters + instead of single-code-unit strings. It is available when PCRE2 is + built to include Unicode support (which is the default). If Unicode + support is not available, the use of this option provokes an error. + Details of how this option changes the behaviour of PCRE2 are given in the pcre2unicode page. COMPILATION ERROR CODES - There are nearly 100 positive error codes that pcre2_compile() may - return (via errorcode) if it finds an error in the pattern. There are - also some negative error codes that are used for invalid UTF strings. + There are nearly 100 positive error codes that pcre2_compile() may + return (via errorcode) if it finds an error in the pattern. There are + also some negative error codes that are used for invalid UTF strings. These are the same as given by pcre2_match() and pcre2_dfa_match(), and - are described in the pcre2unicode page. The pcre2_get_error_message() - function (see "Obtaining a textual error message" below) can be called + are described in the pcre2unicode page. The pcre2_get_error_message() + function (see "Obtaining a textual error message" below) can be called to obtain a textual error message from any error code. @@ -1638,53 +1645,53 @@ JUST-IN-TIME (JIT) COMPILATION void pcre2_jit_stack_free(pcre2_jit_stack *jit_stack); - These functions provide support for JIT compilation, which, if the - just-in-time compiler is available, further processes a compiled pat- + These functions provide support for JIT compilation, which, if the + just-in-time compiler is available, further processes a compiled pat- tern into machine code that executes much faster than the pcre2_match() - interpretive matching function. Full details are given in the pcre2jit + interpretive matching function. Full details are given in the pcre2jit documentation. - JIT compilation is a heavyweight optimization. It can take some time - for patterns to be analyzed, and for one-off matches and simple pat- - terns the benefit of faster execution might be offset by a much slower - compilation time. Most (but not all) patterns can be optimized by the + JIT compilation is a heavyweight optimization. It can take some time + for patterns to be analyzed, and for one-off matches and simple pat- + terns the benefit of faster execution might be offset by a much slower + compilation time. Most (but not all) patterns can be optimized by the JIT compiler. LOCALE SUPPORT - PCRE2 handles caseless matching, and determines whether characters are - letters, digits, or whatever, by reference to a set of tables, indexed - by character code point. This applies only to characters whose code - points are less than 256. By default, higher-valued code points never - match escapes such as \w or \d. However, if PCRE2 is built with Uni- + PCRE2 handles caseless matching, and determines whether characters are + letters, digits, or whatever, by reference to a set of tables, indexed + by character code point. This applies only to characters whose code + points are less than 256. By default, higher-valued code points never + match escapes such as \w or \d. However, if PCRE2 is built with Uni- code support, all characters can be tested with \p and \P, or, alterna- - tively, the PCRE2_UCP option can be set when a pattern is compiled; - this causes \w and friends to use Unicode property support instead of + tively, the PCRE2_UCP option can be set when a pattern is compiled; + this causes \w and friends to use Unicode property support instead of the built-in tables. - The use of locales with Unicode is discouraged. If you are handling - characters with code points greater than 128, you should either use + The use of locales with Unicode is discouraged. If you are handling + characters with code points greater than 128, you should either use Unicode support, or use locales, but not try to mix the two. - PCRE2 contains an internal set of character tables that are used by - default. These are sufficient for many applications. Normally, the + PCRE2 contains an internal set of character tables that are used by + default. These are sufficient for many applications. Normally, the internal tables recognize only ASCII characters. However, when PCRE2 is built, it is possible to cause the internal tables to be rebuilt in the default "C" locale of the local system, which may cause them to be dif- ferent. - The internal tables can be overridden by tables supplied by the appli- - cation that calls PCRE2. These may be created in a different locale - from the default. As more and more applications change to using Uni- + The internal tables can be overridden by tables supplied by the appli- + cation that calls PCRE2. These may be created in a different locale + from the default. As more and more applications change to using Uni- code, the need for this locale support is expected to die away. - External tables are built by calling the pcre2_maketables() function, - in the relevant locale. The result can be passed to pcre2_compile() as - often as necessary, by creating a compile context and calling - pcre2_set_character_tables() to set the tables pointer therein. For - example, to build and use tables that are appropriate for the French - locale (where accented characters with values greater than 128 are + External tables are built by calling the pcre2_maketables() function, + in the relevant locale. The result can be passed to pcre2_compile() as + often as necessary, by creating a compile context and calling + pcre2_set_character_tables() to set the tables pointer therein. For + example, to build and use tables that are appropriate for the French + locale (where accented characters with values greater than 128 are treated as letters), the following code could be used: setlocale(LC_CTYPE, "fr_FR"); @@ -1693,15 +1700,15 @@ LOCALE SUPPORT pcre2_set_character_tables(ccontext, tables); re = pcre2_compile(..., ccontext); - The locale name "fr_FR" is used on Linux and other Unix-like systems; - if you are using Windows, the name for the French locale is "french". - It is the caller's responsibility to ensure that the memory containing + The locale name "fr_FR" is used on Linux and other Unix-like systems; + if you are using Windows, the name for the French locale is "french". + It is the caller's responsibility to ensure that the memory containing the tables remains available for as long as it is needed. The pointer that is passed (via the compile context) to pcre2_compile() - is saved with the compiled pattern, and the same tables are used by - pcre2_match() and pcre_dfa_match(). Thus, for any single pattern, com- - pilation and matching both happen in the same locale, but different + is saved with the compiled pattern, and the same tables are used by + pcre2_match() and pcre_dfa_match(). Thus, for any single pattern, com- + pilation and matching both happen in the same locale, but different patterns can be processed in different locales. @@ -1709,13 +1716,13 @@ INFORMATION ABOUT A COMPILED PATTERN int pcre2_pattern_info(const pcre2 *code, uint32_t what, void *where); - The pcre2_pattern_info() function returns general information about a + The pcre2_pattern_info() function returns general information about a compiled pattern. For information about callouts, see the next section. - The first argument for pcre2_pattern_info() is a pointer to the com- + The first argument for pcre2_pattern_info() is a pointer to the com- piled pattern. The second argument specifies which piece of information - is required, and the third argument is a pointer to a variable to - receive the data. If the third argument is NULL, the first argument is - ignored, and the function returns the size in bytes of the variable + is required, and the third argument is a pointer to a variable to + receive the data. If the third argument is NULL, the first argument is + ignored, and the function returns the size in bytes of the variable that is required for the information requested. Otherwise, the yield of the function is zero for success, or one of the following negative num- bers: @@ -1725,9 +1732,9 @@ INFORMATION ABOUT A COMPILED PATTERN PCRE2_ERROR_BADOPTION the value of what was invalid PCRE2_ERROR_UNSET the requested field is not set - The "magic number" is placed at the start of each compiled pattern as - an simple check against passing an arbitrary memory pointer. Here is a - typical call of pcre2_pattern_info(), to obtain the length of the com- + The "magic number" is placed at the start of each compiled pattern as + an simple check against passing an arbitrary memory pointer. Here is a + typical call of pcre2_pattern_info(), to obtain the length of the com- piled pattern: int rc; @@ -1744,19 +1751,19 @@ INFORMATION ABOUT A COMPILED PATTERN PCRE2_INFO_ARGOPTIONS Return a copy of the pattern's options. The third argument should point - to a uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly the - options that were passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP- - TIONS returns the compile options as modified by any top-level (*XXX) + to a uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly the + options that were passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP- + TIONS returns the compile options as modified by any top-level (*XXX) option settings such as (*UTF) at the start of the pattern itself. - For example, if the pattern /(*UTF)abc/ is compiled with the - PCRE2_EXTENDED option, the result for PCRE2_INFO_ALLOPTIONS is - PCRE2_EXTENDED and PCRE2_UTF. Option settings such as (?i) that can - change within a pattern do not affect the result of PCRE2_INFO_ALLOP- + For example, if the pattern /(*UTF)abc/ is compiled with the + PCRE2_EXTENDED option, the result for PCRE2_INFO_ALLOPTIONS is + PCRE2_EXTENDED and PCRE2_UTF. Option settings such as (?i) that can + change within a pattern do not affect the result of PCRE2_INFO_ALLOP- TIONS, even if they appear right at the start of the pattern. (This was different in some earlier releases.) - A pattern compiled without PCRE2_ANCHORED is automatically anchored by + A pattern compiled without PCRE2_ANCHORED is automatically anchored by PCRE2 if the first significant item in every top-level branch is one of the following: @@ -1765,7 +1772,7 @@ INFORMATION ABOUT A COMPILED PATTERN \G always .* sometimes - see below - When .* is the first significant item, anchoring is possible only when + When .* is the first significant item, anchoring is possible only when all the following are true: .* is not in an atomic group @@ -1775,172 +1782,172 @@ INFORMATION ABOUT A COMPILED PATTERN Neither (*PRUNE) nor (*SKIP) appears in the pattern PCRE2_NO_DOTSTAR_ANCHOR is not set - For patterns that are auto-anchored, the PCRE2_ANCHORED bit is set in + For patterns that are auto-anchored, the PCRE2_ANCHORED bit is set in the options returned for PCRE2_INFO_ALLOPTIONS. PCRE2_INFO_BACKREFMAX - Return the number of the highest back reference in the pattern. The - third argument should point to an uint32_t variable. Named subpatterns - acquire numbers as well as names, and these count towards the highest - back reference. Back references such as \4 or \g{12} match the cap- - tured characters of the given group, but in addition, the check that a + Return the number of the highest back reference in the pattern. The + third argument should point to an uint32_t variable. Named subpatterns + acquire numbers as well as names, and these count towards the highest + back reference. Back references such as \4 or \g{12} match the cap- + tured characters of the given group, but in addition, the check that a capturing group is set in a conditional subpattern such as (?(3)a|b) is - also a back reference. Zero is returned if there are no back refer- + also a back reference. Zero is returned if there are no back refer- ences. PCRE2_INFO_BSR The output is a uint32_t whose value indicates what character sequences the \R escape sequence matches. A value of PCRE2_BSR_UNICODE means that - \R matches any Unicode line ending sequence; a value of PCRE2_BSR_ANY- + \R matches any Unicode line ending sequence; a value of PCRE2_BSR_ANY- CRLF means that \R matches only CR, LF, or CRLF. PCRE2_INFO_CAPTURECOUNT - Return the highest capturing subpattern number in the pattern. In pat- + Return the highest capturing subpattern number in the pattern. In pat- terns where (?| is not used, this is also the total number of capturing subpatterns. The third argument should point to an uint32_t variable. PCRE2_INFO_DEPTHLIMIT - If the pattern set a backtracking depth limit by including an item of - the form (*LIMIT_DEPTH=nnnn) at the start, the value is returned. The - third argument should point to an unsigned 32-bit integer. If no such - value has been set, the call to pcre2_pattern_info() returns the error + If the pattern set a backtracking depth limit by including an item of + the form (*LIMIT_DEPTH=nnnn) at the start, the value is returned. The + third argument should point to an unsigned 32-bit integer. If no such + value has been set, the call to pcre2_pattern_info() returns the error PCRE2_ERROR_UNSET. PCRE2_INFO_FIRSTBITMAP - In the absence of a single first code unit for a non-anchored pattern, - pcre2_compile() may construct a 256-bit table that defines a fixed set - of values for the first code unit in any match. For example, a pattern - that starts with [abc] results in a table with three bits set. When - code unit values greater than 255 are supported, the flag bit for 255 - means "any code unit of value 255 or above". If such a table was con- - structed, a pointer to it is returned. Otherwise NULL is returned. The + In the absence of a single first code unit for a non-anchored pattern, + pcre2_compile() may construct a 256-bit table that defines a fixed set + of values for the first code unit in any match. For example, a pattern + that starts with [abc] results in a table with three bits set. When + code unit values greater than 255 are supported, the flag bit for 255 + means "any code unit of value 255 or above". If such a table was con- + structed, a pointer to it is returned. Otherwise NULL is returned. The third argument should point to an const uint8_t * variable. PCRE2_INFO_FIRSTCODETYPE Return information about the first code unit of any matched string, for - a non-anchored pattern. The third argument should point to an uint32_t - variable. If there is a fixed first value, for example, the letter "c" + a non-anchored pattern. The third argument should point to an uint32_t + variable. If there is a fixed first value, for example, the letter "c" from a pattern such as (cat|cow|coyote), 1 is returned, and the charac- - ter value can be retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is - no fixed first value, but it is known that a match can occur only at - the start of the subject or following a newline in the subject, 2 is + ter value can be retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is + no fixed first value, but it is known that a match can occur only at + the start of the subject or following a newline in the subject, 2 is returned. Otherwise, and for anchored patterns, 0 is returned. PCRE2_INFO_FIRSTCODEUNIT - Return the value of the first code unit of any matched string in the + Return the value of the first code unit of any matched string in the situation where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0. - The third argument should point to an uint32_t variable. In the 8-bit - library, the value is always less than 256. In the 16-bit library the - value can be up to 0xffff. In the 32-bit library in UTF-32 mode the + The third argument should point to an uint32_t variable. In the 8-bit + library, the value is always less than 256. In the 16-bit library the + value can be up to 0xffff. In the 32-bit library in UTF-32 mode the value can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32 mode. PCRE2_INFO_FRAMESIZE Return the size (in bytes) of the data frames that are used to remember - backtracking positions when the pattern is processed by pcre2_match() - without the use of JIT. The third argument should point to an size_t + backtracking positions when the pattern is processed by pcre2_match() + without the use of JIT. The third argument should point to an size_t variable. The frame size depends on the number of capturing parentheses - in the pattern. Each additional capturing group adds two PCRE2_SIZE + in the pattern. Each additional capturing group adds two PCRE2_SIZE variables. PCRE2_INFO_HASBACKSLASHC - Return 1 if the pattern contains any instances of \C, otherwise 0. The + Return 1 if the pattern contains any instances of \C, otherwise 0. The third argument should point to an uint32_t variable. PCRE2_INFO_HASCRORLF - Return 1 if the pattern contains any explicit matches for CR or LF + Return 1 if the pattern contains any explicit matches for CR or LF characters, otherwise 0. The third argument should point to an uint32_t - variable. An explicit match is either a literal CR or LF character, or - \r or \n or one of the equivalent hexadecimal or octal escape + variable. An explicit match is either a literal CR or LF character, or + \r or \n or one of the equivalent hexadecimal or octal escape sequences. PCRE2_INFO_HEAPLIMIT If the pattern set a heap memory limit by including an item of the form (*LIMIT_HEAP=nnnn) at the start, the value is returned. The third argu- - ment should point to an unsigned 32-bit integer. If no such value has - been set, the call to pcre2_pattern_info() returns the error + ment should point to an unsigned 32-bit integer. If no such value has + been set, the call to pcre2_pattern_info() returns the error PCRE2_ERROR_UNSET. PCRE2_INFO_JCHANGED - Return 1 if the (?J) or (?-J) option setting is used in the pattern, - otherwise 0. The third argument should point to an uint32_t variable. - (?J) and (?-J) set and unset the local PCRE2_DUPNAMES option, respec- + Return 1 if the (?J) or (?-J) option setting is used in the pattern, + otherwise 0. The third argument should point to an uint32_t variable. + (?J) and (?-J) set and unset the local PCRE2_DUPNAMES option, respec- tively. PCRE2_INFO_JITSIZE - If the compiled pattern was successfully processed by pcre2_jit_com- - pile(), return the size of the JIT compiled code, otherwise return + If the compiled pattern was successfully processed by pcre2_jit_com- + pile(), return the size of the JIT compiled code, otherwise return zero. The third argument should point to a size_t variable. PCRE2_INFO_LASTCODETYPE - Returns 1 if there is a rightmost literal code unit that must exist in - any matched string, other than at its start. The third argument should - point to an uint32_t variable. If there is no such value, 0 is - returned. When 1 is returned, the code unit value itself can be - retrieved using PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last - literal value is recorded only if it follows something of variable - length. For example, for the pattern /^a\d+z\d+/ the returned value is - 1 (with "z" returned from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/ + Returns 1 if there is a rightmost literal code unit that must exist in + any matched string, other than at its start. The third argument should + point to an uint32_t variable. If there is no such value, 0 is + returned. When 1 is returned, the code unit value itself can be + retrieved using PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last + literal value is recorded only if it follows something of variable + length. For example, for the pattern /^a\d+z\d+/ the returned value is + 1 (with "z" returned from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/ the returned value is 0. PCRE2_INFO_LASTCODEUNIT - Return the value of the rightmost literal data unit that must exist in - any matched string, other than at its start, if such a value has been - recorded. The third argument should point to an uint32_t variable. If + Return the value of the rightmost literal data unit that must exist in + any matched string, other than at its start, if such a value has been + recorded. The third argument should point to an uint32_t variable. If there is no such value, 0 is returned. PCRE2_INFO_MATCHEMPTY - Return 1 if the pattern might match an empty string, otherwise 0. The - third argument should point to an uint32_t variable. When a pattern + Return 1 if the pattern might match an empty string, otherwise 0. The + third argument should point to an uint32_t variable. When a pattern contains recursive subroutine calls it is not always possible to deter- - mine whether or not it can match an empty string. PCRE2 takes a cau- + mine whether or not it can match an empty string. PCRE2 takes a cau- tious approach and returns 1 in such cases. PCRE2_INFO_MATCHLIMIT - If the pattern set a match limit by including an item of the form - (*LIMIT_MATCH=nnnn) at the start, the value is returned. The third - argument should point to an unsigned 32-bit integer. If no such value - has been set, the call to pcre2_pattern_info() returns the error + If the pattern set a match limit by including an item of the form + (*LIMIT_MATCH=nnnn) at the start, the value is returned. The third + argument should point to an unsigned 32-bit integer. If no such value + has been set, the call to pcre2_pattern_info() returns the error PCRE2_ERROR_UNSET. PCRE2_INFO_MAXLOOKBEHIND Return the number of characters (not code units) in the longest lookbe- - hind assertion in the pattern. The third argument should point to an - unsigned 32-bit integer. This information is useful when doing multi- - segment matching using the partial matching facilities. Note that the + hind assertion in the pattern. The third argument should point to an + unsigned 32-bit integer. This information is useful when doing multi- + segment matching using the partial matching facilities. Note that the simple assertions \b and \B require a one-character lookbehind. \A also - registers a one-character lookbehind, though it does not actually - inspect the previous character. This is to ensure that at least one - character from the old segment is retained when a new segment is pro- + registers a one-character lookbehind, though it does not actually + inspect the previous character. This is to ensure that at least one + character from the old segment is retained when a new segment is pro- cessed. Otherwise, if there are no lookbehinds in the pattern, \A might match incorrectly at the start of a new segment. PCRE2_INFO_MINLENGTH - If a minimum length for matching subject strings was computed, its - value is returned. Otherwise the returned value is 0. The value is a - number of characters, which in UTF mode may be different from the num- - ber of code units. The third argument should point to an uint32_t - variable. The value is a lower bound to the length of any matching - string. There may not be any strings of that length that do actually + If a minimum length for matching subject strings was computed, its + value is returned. Otherwise the returned value is 0. The value is a + number of characters, which in UTF mode may be different from the num- + ber of code units. The third argument should point to an uint32_t + variable. The value is a lower bound to the length of any matching + string. There may not be any strings of that length that do actually match, but every string that does match is at least that long. PCRE2_INFO_NAMECOUNT @@ -1948,50 +1955,50 @@ INFORMATION ABOUT A COMPILED PATTERN PCRE2_INFO_NAMETABLE PCRE2 supports the use of named as well as numbered capturing parenthe- - ses. The names are just an additional way of identifying the parenthe- + ses. The names are just an additional way of identifying the parenthe- ses, which still acquire numbers. Several convenience functions such as - pcre2_substring_get_byname() are provided for extracting captured sub- - strings by name. It is also possible to extract the data directly, by - first converting the name to a number in order to access the correct - pointers in the output vector (described with pcre2_match() below). To - do the conversion, you need to use the name-to-number map, which is + pcre2_substring_get_byname() are provided for extracting captured sub- + strings by name. It is also possible to extract the data directly, by + first converting the name to a number in order to access the correct + pointers in the output vector (described with pcre2_match() below). To + do the conversion, you need to use the name-to-number map, which is described by these three values. - The map consists of a number of fixed-size entries. PCRE2_INFO_NAME- - COUNT gives the number of entries, and PCRE2_INFO_NAMEENTRYSIZE gives - the size of each entry in code units; both of these return a uint32_t + The map consists of a number of fixed-size entries. PCRE2_INFO_NAME- + COUNT gives the number of entries, and PCRE2_INFO_NAMEENTRYSIZE gives + the size of each entry in code units; both of these return a uint32_t value. The entry size depends on the length of the longest name. PCRE2_INFO_NAMETABLE returns a pointer to the first entry of the table. - This is a PCRE2_SPTR pointer to a block of code units. In the 8-bit - library, the first two bytes of each entry are the number of the cap- + This is a PCRE2_SPTR pointer to a block of code units. In the 8-bit + library, the first two bytes of each entry are the number of the cap- turing parenthesis, most significant byte first. In the 16-bit library, - the pointer points to 16-bit code units, the first of which contains - the parenthesis number. In the 32-bit library, the pointer points to - 32-bit code units, the first of which contains the parenthesis number. + the pointer points to 16-bit code units, the first of which contains + the parenthesis number. In the 32-bit library, the pointer points to + 32-bit code units, the first of which contains the parenthesis number. The rest of the entry is the corresponding name, zero terminated. - The names are in alphabetical order. If (?| is used to create multiple - groups with the same number, as described in the section on duplicate - subpattern numbers in the pcre2pattern page, the groups may be given - the same name, but there is only one entry in the table. Different + The names are in alphabetical order. If (?| is used to create multiple + groups with the same number, as described in the section on duplicate + subpattern numbers in the pcre2pattern page, the groups may be given + the same name, but there is only one entry in the table. Different names for groups of the same number are not permitted. - Duplicate names for subpatterns with different numbers are permitted, - but only if PCRE2_DUPNAMES is set. They appear in the table in the - order in which they were found in the pattern. In the absence of (?| - this is the order of increasing number; when (?| is used this is not + Duplicate names for subpatterns with different numbers are permitted, + but only if PCRE2_DUPNAMES is set. They appear in the table in the + order in which they were found in the pattern. In the absence of (?| + this is the order of increasing number; when (?| is used this is not necessarily the case because later subpatterns may have lower numbers. - As a simple example of the name/number table, consider the following - pattern after compilation by the 8-bit library (assume PCRE2_EXTENDED + As a simple example of the name/number table, consider the following + pattern after compilation by the 8-bit library (assume PCRE2_EXTENDED is set, so white space - including newlines - is ignored): (?<date> (?<year>(\d\d)?\d\d) - (?<month>\d\d) - (?<day>\d\d) ) - There are four named subpatterns, so the table has four entries, and - each entry in the table is eight bytes long. The table is as follows, + There are four named subpatterns, so the table has four entries, and + each entry in the table is eight bytes long. The table is as follows, with non-printing bytes shows in hexadecimal, and undefined bytes shown as ??: @@ -2000,8 +2007,8 @@ INFORMATION ABOUT A COMPILED PATTERN 00 04 m o n t h 00 00 02 y e a r 00 ?? - When writing code to extract data from named subpatterns using the - name-to-number map, remember that the length of the entries is likely + When writing code to extract data from named subpatterns using the + name-to-number map, remember that the length of the entries is likely to be different for each compiled pattern. PCRE2_INFO_NEWLINE @@ -2019,14 +2026,14 @@ INFORMATION ABOUT A COMPILED PATTERN PCRE2_INFO_SIZE - Return the size of the compiled pattern in bytes (for all three - libraries). The third argument should point to a size_t variable. This - value includes the size of the general data block that precedes the - code units of the compiled pattern itself. The value that is used when - pcre2_compile() is getting memory in which to place the compiled pat- - tern may be slightly larger than the value returned by this option, - because there are cases where the code that calculates the size has to - over-estimate. Processing a pattern with the JIT compiler does not + Return the size of the compiled pattern in bytes (for all three + libraries). The third argument should point to a size_t variable. This + value includes the size of the general data block that precedes the + code units of the compiled pattern itself. The value that is used when + pcre2_compile() is getting memory in which to place the compiled pat- + tern may be slightly larger than the value returned by this option, + because there are cases where the code that calculates the size has to + over-estimate. Processing a pattern with the JIT compiler does not alter the value returned by this option. @@ -2037,22 +2044,22 @@ INFORMATION ABOUT A PATTERN'S CALLOUTS void *user_data); A script language that supports the use of string arguments in callouts - might like to scan all the callouts in a pattern before running the + might like to scan all the callouts in a pattern before running the match. This can be done by calling pcre2_callout_enumerate(). The first - argument is a pointer to a compiled pattern, the second points to a - callback function, and the third is arbitrary user data. The callback - function is called for every callout in the pattern in the order in + argument is a pointer to a compiled pattern, the second points to a + callback function, and the third is arbitrary user data. The callback + function is called for every callout in the pattern in the order in which they appear. Its first argument is a pointer to a callout enumer- - ation block, and its second argument is the user_data value that was - passed to pcre2_callout_enumerate(). The contents of the callout enu- - meration block are described in the pcre2callout documentation, which + ation block, and its second argument is the user_data value that was + passed to pcre2_callout_enumerate(). The contents of the callout enu- + meration block are described in the pcre2callout documentation, which also gives further details about callouts. SERIALIZATION AND PRECOMPILING - It is possible to save compiled patterns on disc or elsewhere, and - reload them later, subject to a number of restrictions. The functions + It is possible to save compiled patterns on disc or elsewhere, and + reload them later, subject to a number of restrictions. The functions whose names begin with pcre2_serialize_ are used for this purpose. They are described in the pcre2serialize documentation. @@ -2067,56 +2074,56 @@ THE MATCH DATA BLOCK void pcre2_match_data_free(pcre2_match_data *match_data); - Information about a successful or unsuccessful match is placed in a - match data block, which is an opaque structure that is accessed by - function calls. In particular, the match data block contains a vector - of offsets into the subject string that define the matched part of the - subject and any substrings that were captured. This is known as the + Information about a successful or unsuccessful match is placed in a + match data block, which is an opaque structure that is accessed by + function calls. In particular, the match data block contains a vector + of offsets into the subject string that define the matched part of the + subject and any substrings that were captured. This is known as the ovector. - Before calling pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match() + Before calling pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match() you must create a match data block by calling one of the creation func- - tions above. For pcre2_match_data_create(), the first argument is the - number of pairs of offsets in the ovector. One pair of offsets is + tions above. For pcre2_match_data_create(), the first argument is the + number of pairs of offsets in the ovector. One pair of offsets is required to identify the string that matched the whole pattern, with an - additional pair for each captured substring. For example, a value of 4 - creates enough space to record the matched portion of the subject plus - three captured substrings. A minimum of at least 1 pair is imposed by + additional pair for each captured substring. For example, a value of 4 + creates enough space to record the matched portion of the subject plus + three captured substrings. A minimum of at least 1 pair is imposed by pcre2_match_data_create(), so it is always possible to return the over- all matched string. The second argument of pcre2_match_data_create() is a pointer to a gen- - eral context, which can specify custom memory management for obtaining + eral context, which can specify custom memory management for obtaining the memory for the match data block. If you are not using custom memory management, pass NULL, which causes malloc() to be used. - For pcre2_match_data_create_from_pattern(), the first argument is a + For pcre2_match_data_create_from_pattern(), the first argument is a pointer to a compiled pattern. The ovector is created to be exactly the right size to hold all the substrings a pattern might capture. The sec- - ond argument is again a pointer to a general context, but in this case + ond argument is again a pointer to a general context, but in this case if NULL is passed, the memory is obtained using the same allocator that was used for the compiled pattern (custom or default). - A match data block can be used many times, with the same or different - compiled patterns. You can extract information from a match data block + A match data block can be used many times, with the same or different + compiled patterns. You can extract information from a match data block after a match operation has finished, using functions that are - described in the sections on matched strings and other match data + described in the sections on matched strings and other match data below. - When a call of pcre2_match() fails, valid data is available in the - match block only when the error is PCRE2_ERROR_NOMATCH, - PCRE2_ERROR_PARTIAL, or one of the error codes for an invalid UTF + When a call of pcre2_match() fails, valid data is available in the + match block only when the error is PCRE2_ERROR_NOMATCH, + PCRE2_ERROR_PARTIAL, or one of the error codes for an invalid UTF string. Exactly what is available depends on the error, and is detailed below. - When one of the matching functions is called, pointers to the compiled - pattern and the subject string are set in the match data block so that - they can be referenced by the extraction functions. After running a - match, you must not free a compiled pattern or a subject string until - after all operations on the match data block (for that match) have + When one of the matching functions is called, pointers to the compiled + pattern and the subject string are set in the match data block so that + they can be referenced by the extraction functions. After running a + match, you must not free a compiled pattern or a subject string until + after all operations on the match data block (for that match) have taken place. - When a match data block itself is no longer needed, it should be freed + When a match data block itself is no longer needed, it should be freed by calling pcre2_match_data_free(). @@ -2127,15 +2134,15 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION uint32_t options, pcre2_match_data *match_data, pcre2_match_context *mcontext); - The function pcre2_match() is called to match a subject string against - a compiled pattern, which is passed in the code argument. You can call + The function pcre2_match() is called to match a subject string against + a compiled pattern, which is passed in the code argument. You can call pcre2_match() with the same code argument as many times as you like, in - order to find multiple matches in the subject string or to match dif- + order to find multiple matches in the subject string or to match dif- ferent subject strings with the same pattern. - This function is the main matching facility of the library, and it - operates in a Perl-like manner. For specialist use there is also an - alternative matching function, which is described below in the section + This function is the main matching facility of the library, and it + operates in a Perl-like manner. For specialist use there is also an + alternative matching function, which is described below in the section about the pcre2_dfa_match() function. Here is an example of a simple call to pcre2_match(): @@ -2150,187 +2157,187 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION match_data, /* the match data block */ NULL); /* a match context; NULL means use defaults */ - If the subject string is zero-terminated, the length can be given as + If the subject string is zero-terminated, the length can be given as PCRE2_ZERO_TERMINATED. A match context must be provided if certain less common matching parameters are to be changed. For details, see the sec- tion on the match context above. The string to be matched by pcre2_match() - The subject string is passed to pcre2_match() as a pointer in subject, - a length in length, and a starting offset in startoffset. The length - and offset are in code units, not characters. That is, they are in - bytes for the 8-bit library, 16-bit code units for the 16-bit library, - and 32-bit code units for the 32-bit library, whether or not UTF pro- + The subject string is passed to pcre2_match() as a pointer in subject, + a length in length, and a starting offset in startoffset. The length + and offset are in code units, not characters. That is, they are in + bytes for the 8-bit library, 16-bit code units for the 16-bit library, + and 32-bit code units for the 32-bit library, whether or not UTF pro- cessing is enabled. If startoffset is greater than the length of the subject, pcre2_match() - returns PCRE2_ERROR_BADOFFSET. When the starting offset is zero, the - search for a match starts at the beginning of the subject, and this is + returns PCRE2_ERROR_BADOFFSET. When the starting offset is zero, the + search for a match starts at the beginning of the subject, and this is by far the most common case. In UTF-8 or UTF-16 mode, the starting off- - set must point to the start of a character, or to the end of the sub- - ject (in UTF-32 mode, one code unit equals one character, so all off- - sets are valid). Like the pattern string, the subject may contain + set must point to the start of a character, or to the end of the sub- + ject (in UTF-32 mode, one code unit equals one character, so all off- + sets are valid). Like the pattern string, the subject may contain binary zeroes. - A non-zero starting offset is useful when searching for another match - in the same subject by calling pcre2_match() again after a previous - success. Setting startoffset differs from passing over a shortened - string and setting PCRE2_NOTBOL in the case of a pattern that begins + A non-zero starting offset is useful when searching for another match + in the same subject by calling pcre2_match() again after a previous + success. Setting startoffset differs from passing over a shortened + string and setting PCRE2_NOTBOL in the case of a pattern that begins with any kind of lookbehind. For example, consider the pattern \Biss\B - which finds occurrences of "iss" in the middle of words. (\B matches - only if the current position in the subject is not a word boundary.) + which finds occurrences of "iss" in the middle of words. (\B matches + only if the current position in the subject is not a word boundary.) When applied to the string "Mississipi" the first call to pcre2_match() - finds the first occurrence. If pcre2_match() is called again with just - the remainder of the subject, namely "issipi", it does not match, + finds the first occurrence. If pcre2_match() is called again with just + the remainder of the subject, namely "issipi", it does not match, because \B is always false at the start of the subject, which is deemed - to be a word boundary. However, if pcre2_match() is passed the entire + to be a word boundary. However, if pcre2_match() is passed the entire string again, but with startoffset set to 4, it finds the second occur- - rence of "iss" because it is able to look behind the starting point to + rence of "iss" because it is able to look behind the starting point to discover that it is preceded by a letter. - Finding all the matches in a subject is tricky when the pattern can + Finding all the matches in a subject is tricky when the pattern can match an empty string. It is possible to emulate Perl's /g behaviour by - first trying the match again at the same offset, with the - PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED options, and then if that - fails, advancing the starting offset and trying an ordinary match - again. There is some code that demonstrates how to do this in the - pcre2demo sample program. In the most general case, you have to check - to see if the newline convention recognizes CRLF as a newline, and if - so, and the current character is CR followed by LF, advance the start- + first trying the match again at the same offset, with the + PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED options, and then if that + fails, advancing the starting offset and trying an ordinary match + again. There is some code that demonstrates how to do this in the + pcre2demo sample program. In the most general case, you have to check + to see if the newline convention recognizes CRLF as a newline, and if + so, and the current character is CR followed by LF, advance the start- ing offset by two characters instead of one. - If a non-zero starting offset is passed when the pattern is anchored, - an single attempt to match at the given offset is made. This can only + If a non-zero starting offset is passed when the pattern is anchored, + an single attempt to match at the given offset is made. This can only succeed if the pattern does not require the match to be at the start of - the subject. In other words, the anchoring must be the result of set- - ting the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL, not + the subject. In other words, the anchoring must be the result of set- + ting the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL, not by starting the pattern with ^ or \A. Option bits for pcre2_match() The unused bits of the options argument for pcre2_match() must be zero. - The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDANCHORED, - PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART, - PCRE2_NO_JIT, PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PAR- + The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDANCHORED, + PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART, + PCRE2_NO_JIT, PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PAR- TIAL_SOFT. Their action is described below. - Setting PCRE2_ANCHORED or PCRE2_ENDANCHORED at match time is not sup- - ported by the just-in-time (JIT) compiler. If it is set, JIT matching - is disabled and the interpretive code in pcre2_match() is run. Apart - from PCRE2_NO_JIT (obviously), the remaining options are supported for + Setting PCRE2_ANCHORED or PCRE2_ENDANCHORED at match time is not sup- + ported by the just-in-time (JIT) compiler. If it is set, JIT matching + is disabled and the interpretive code in pcre2_match() is run. Apart + from PCRE2_NO_JIT (obviously), the remaining options are supported for JIT matching. PCRE2_ANCHORED The PCRE2_ANCHORED option limits pcre2_match() to matching at the first - matching position. If a pattern was compiled with PCRE2_ANCHORED, or - turned out to be anchored by virtue of its contents, it cannot be made - unachored at matching time. Note that setting the option at match time + matching position. If a pattern was compiled with PCRE2_ANCHORED, or + turned out to be anchored by virtue of its contents, it cannot be made + unachored at matching time. Note that setting the option at match time disables JIT matching. PCRE2_ENDANCHORED - If the PCRE2_ENDANCHORED option is set, any string that pcre2_match() - matches must be right at the end of the subject string. Note that set- + If the PCRE2_ENDANCHORED option is set, any string that pcre2_match() + matches must be right at the end of the subject string. Note that set- ting the option at match time disables JIT matching. PCRE2_NOTBOL This option specifies that first character of the subject string is not - the beginning of a line, so the circumflex metacharacter should not - match before it. Setting this without having set PCRE2_MULTILINE at + the beginning of a line, so the circumflex metacharacter should not + match before it. Setting this without having set PCRE2_MULTILINE at compile time causes circumflex never to match. This option affects only the behaviour of the circumflex metacharacter. It does not affect \A. PCRE2_NOTEOL This option specifies that the end of the subject string is not the end - of a line, so the dollar metacharacter should not match it nor (except - in multiline mode) a newline immediately before it. Setting this with- - out having set PCRE2_MULTILINE at compile time causes dollar never to + of a line, so the dollar metacharacter should not match it nor (except + in multiline mode) a newline immediately before it. Setting this with- + out having set PCRE2_MULTILINE at compile time causes dollar never to match. This option affects only the behaviour of the dollar metacharac- ter. It does not affect \Z or \z. PCRE2_NOTEMPTY An empty string is not considered to be a valid match if this option is - set. If there are alternatives in the pattern, they are tried. If all - the alternatives match the empty string, the entire match fails. For + set. If there are alternatives in the pattern, they are tried. If all + the alternatives match the empty string, the entire match fails. For example, if the pattern a?b? - is applied to a string not beginning with "a" or "b", it matches an + is applied to a string not beginning with "a" or "b", it matches an empty string at the start of the subject. With PCRE2_NOTEMPTY set, this - match is not valid, so pcre2_match() searches further into the string + match is not valid, so pcre2_match() searches further into the string for occurrences of "a" or "b". PCRE2_NOTEMPTY_ATSTART - This is like PCRE2_NOTEMPTY, except that it locks out an empty string + This is like PCRE2_NOTEMPTY, except that it locks out an empty string match only at the first matching position, that is, at the start of the - subject plus the starting offset. An empty string match later in the - subject is permitted. If the pattern is anchored, such a match can + subject plus the starting offset. An empty string match later in the + subject is permitted. If the pattern is anchored, such a match can occur only if the pattern contains \K. PCRE2_NO_JIT - By default, if a pattern has been successfully processed by - pcre2_jit_compile(), JIT is automatically used when pcre2_match() is - called with options that JIT supports. Setting PCRE2_NO_JIT disables + By default, if a pattern has been successfully processed by + pcre2_jit_compile(), JIT is automatically used when pcre2_match() is + called with options that JIT supports. Setting PCRE2_NO_JIT disables the use of JIT; it forces matching to be done by the interpreter. PCRE2_NO_UTF_CHECK When PCRE2_UTF is set at compile time, the validity of the subject as a - UTF string is checked by default when pcre2_match() is subsequently - called. If a non-zero starting offset is given, the check is applied - only to that part of the subject that could be inspected during match- - ing, and there is a check that the starting offset points to the first - code unit of a character or to the end of the subject. If there are no - lookbehind assertions in the pattern, the check starts at the starting - offset. Otherwise, it starts at the length of the longest lookbehind + UTF string is checked by default when pcre2_match() is subsequently + called. If a non-zero starting offset is given, the check is applied + only to that part of the subject that could be inspected during match- + ing, and there is a check that the starting offset points to the first + code unit of a character or to the end of the subject. If there are no + lookbehind assertions in the pattern, the check starts at the starting + offset. Otherwise, it starts at the length of the longest lookbehind before the starting offset, or at the start of the subject if there are - not that many characters before the starting offset. Note that the + not that many characters before the starting offset. Note that the sequences \b and \B are one-character lookbehinds. The check is carried out before any other processing takes place, and a - negative error code is returned if the check fails. There are several - UTF error codes for each code unit width, corresponding to different - problems with the code unit sequence. There are discussions about the - validity of UTF-8 strings, UTF-16 strings, and UTF-32 strings in the + negative error code is returned if the check fails. There are several + UTF error codes for each code unit width, corresponding to different + problems with the code unit sequence. There are discussions about the + validity of UTF-8 strings, UTF-16 strings, and UTF-32 strings in the pcre2unicode page. - If you know that your subject is valid, and you want to skip these - checks for performance reasons, you can set the PCRE2_NO_UTF_CHECK - option when calling pcre2_match(). You might want to do this for the + If you know that your subject is valid, and you want to skip these + checks for performance reasons, you can set the PCRE2_NO_UTF_CHECK + option when calling pcre2_match(). You might want to do this for the second and subsequent calls to pcre2_match() if you are making repeated calls to find other matches in the same subject string. - WARNING: When PCRE2_NO_UTF_CHECK is set, the effect of passing an - invalid string as a subject, or an invalid value of startoffset, is + WARNING: When PCRE2_NO_UTF_CHECK is set, the effect of passing an + invalid string as a subject, or an invalid value of startoffset, is undefined. Your program may crash or loop indefinitely. PCRE2_PARTIAL_HARD PCRE2_PARTIAL_SOFT - These options turn on the partial matching feature. A partial match - occurs if the end of the subject string is reached successfully, but - there are not enough subject characters to complete the match. If this - happens when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD) is set, - matching continues by testing any remaining alternatives. Only if no - complete match can be found is PCRE2_ERROR_PARTIAL returned instead of - PCRE2_ERROR_NOMATCH. In other words, PCRE2_PARTIAL_SOFT specifies that - the caller is prepared to handle a partial match, but only if no com- + These options turn on the partial matching feature. A partial match + occurs if the end of the subject string is reached successfully, but + there are not enough subject characters to complete the match. If this + happens when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD) is set, + matching continues by testing any remaining alternatives. Only if no + complete match can be found is PCRE2_ERROR_PARTIAL returned instead of + PCRE2_ERROR_NOMATCH. In other words, PCRE2_PARTIAL_SOFT specifies that + the caller is prepared to handle a partial match, but only if no com- plete match can be found. - If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this - case, if a partial match is found, pcre2_match() immediately returns - PCRE2_ERROR_PARTIAL, without considering any other alternatives. In + If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this + case, if a partial match is found, pcre2_match() immediately returns + PCRE2_ERROR_PARTIAL, without considering any other alternatives. In other words, when PCRE2_PARTIAL_HARD is set, a partial match is consid- ered to be more important that an alternative complete match. @@ -2340,38 +2347,38 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION NEWLINE HANDLING WHEN MATCHING - When PCRE2 is built, a default newline convention is set; this is usu- - ally the standard convention for the operating system. The default can - be overridden in a compile context by calling pcre2_set_newline(). It - can also be overridden by starting a pattern string with, for example, - (*CRLF), as described in the section on newline conventions in the - pcre2pattern page. During matching, the newline choice affects the be- - haviour of the dot, circumflex, and dollar metacharacters. It may also - alter the way the match starting position is advanced after a match + When PCRE2 is built, a default newline convention is set; this is usu- + ally the standard convention for the operating system. The default can + be overridden in a compile context by calling pcre2_set_newline(). It + can also be overridden by starting a pattern string with, for example, + (*CRLF), as described in the section on newline conventions in the + pcre2pattern page. During matching, the newline choice affects the be- + haviour of the dot, circumflex, and dollar metacharacters. It may also + alter the way the match starting position is advanced after a match failure for an unanchored pattern. When PCRE2_NEWLINE_CRLF, PCRE2_NEWLINE_ANYCRLF, or PCRE2_NEWLINE_ANY is - set as the newline convention, and a match attempt for an unanchored + set as the newline convention, and a match attempt for an unanchored pattern fails when the current starting position is at a CRLF sequence, - and the pattern contains no explicit matches for CR or LF characters, - the match position is advanced by two characters instead of one, in + and the pattern contains no explicit matches for CR or LF characters, + the match position is advanced by two characters instead of one, in other words, to after the CRLF. The above rule is a compromise that makes the most common cases work as - expected. For example, if the pattern is .+A (and the PCRE2_DOTALL + expected. For example, if the pattern is .+A (and the PCRE2_DOTALL option is not set), it does not match the string "\r\nA" because, after - failing at the start, it skips both the CR and the LF before retrying. - However, the pattern [\r\n]A does match that string, because it con- + failing at the start, it skips both the CR and the LF before retrying. + However, the pattern [\r\n]A does match that string, because it con- tains an explicit CR or LF reference, and so advances only by one char- acter after the first failure. An explicit match for CR of LF is either a literal appearance of one of - those characters in the pattern, or one of the \r or \n or equivalent + those characters in the pattern, or one of the \r or \n or equivalent octal or hexadecimal escape sequences. Implicit matches such as [^X] do - not count, nor does \s, even though it includes CR and LF in the char- + not count, nor does \s, even though it includes CR and LF in the char- acters that it matches. - Notwithstanding the above, anomalous effects may still occur when CRLF + Notwithstanding the above, anomalous effects may still occur when CRLF is a valid newline sequence and explicit \r or \n escapes appear in the pattern. @@ -2382,81 +2389,81 @@ HOW PCRE2_MATCH() RETURNS A STRING AND CAPTURED SUBSTRINGS PCRE2_SIZE *pcre2_get_ovector_pointer(pcre2_match_data *match_data); - In general, a pattern matches a certain portion of the subject, and in - addition, further substrings from the subject may be picked out by - parenthesized parts of the pattern. Following the usage in Jeffrey - Friedl's book, this is called "capturing" in what follows, and the - phrase "capturing subpattern" or "capturing group" is used for a frag- - ment of a pattern that picks out a substring. PCRE2 supports several + In general, a pattern matches a certain portion of the subject, and in + addition, further substrings from the subject may be picked out by + parenthesized parts of the pattern. Following the usage in Jeffrey + Friedl's book, this is called "capturing" in what follows, and the + phrase "capturing subpattern" or "capturing group" is used for a frag- + ment of a pattern that picks out a substring. PCRE2 supports several other kinds of parenthesized subpattern that do not cause substrings to - be captured. The pcre2_pattern_info() function can be used to find out + be captured. The pcre2_pattern_info() function can be used to find out how many capturing subpatterns there are in a compiled pattern. - You can use auxiliary functions for accessing captured substrings by + You can use auxiliary functions for accessing captured substrings by number or by name, as described in sections below. Alternatively, you can make direct use of the vector of PCRE2_SIZE val- - ues, called the ovector, which contains the offsets of captured - strings. It is part of the match data block. The function - pcre2_get_ovector_pointer() returns the address of the ovector, and + ues, called the ovector, which contains the offsets of captured + strings. It is part of the match data block. The function + pcre2_get_ovector_pointer() returns the address of the ovector, and pcre2_get_ovector_count() returns the number of pairs of values it con- tains. Within the ovector, the first in each pair of values is set to the off- set of the first code unit of a substring, and the second is set to the - offset of the first code unit after the end of a substring. These val- - ues are always code unit offsets, not character offsets. That is, they - are byte offsets in the 8-bit library, 16-bit offsets in the 16-bit + offset of the first code unit after the end of a substring. These val- + ues are always code unit offsets, not character offsets. That is, they + are byte offsets in the 8-bit library, 16-bit offsets in the 16-bit library, and 32-bit offsets in the 32-bit library. - After a partial match (error return PCRE2_ERROR_PARTIAL), only the - first pair of offsets (that is, ovector[0] and ovector[1]) are set. - They identify the part of the subject that was partially matched. See + After a partial match (error return PCRE2_ERROR_PARTIAL), only the + first pair of offsets (that is, ovector[0] and ovector[1]) are set. + They identify the part of the subject that was partially matched. See the pcre2partial documentation for details of partial matching. - After a fully successful match, the first pair of offsets identifies - the portion of the subject string that was matched by the entire pat- - tern. The next pair is used for the first captured substring, and so - on. The value returned by pcre2_match() is one more than the highest - numbered pair that has been set. For example, if two substrings have - been captured, the returned value is 3. If there are no captured sub- + After a fully successful match, the first pair of offsets identifies + the portion of the subject string that was matched by the entire pat- + tern. The next pair is used for the first captured substring, and so + on. The value returned by pcre2_match() is one more than the highest + numbered pair that has been set. For example, if two substrings have + been captured, the returned value is 3. If there are no captured sub- strings, the return value from a successful match is 1, indicating that just the first pair of offsets has been set. - If a pattern uses the \K escape sequence within a positive assertion, + If a pattern uses the \K escape sequence within a positive assertion, the reported start of a successful match can be greater than the end of - the match. For example, if the pattern (?=ab\K) is matched against + the match. For example, if the pattern (?=ab\K) is matched against "ab", the start and end offset values for the match are 2 and 0. - If a capturing subpattern group is matched repeatedly within a single - match operation, it is the last portion of the subject that it matched + If a capturing subpattern group is matched repeatedly within a single + match operation, it is the last portion of the subject that it matched that is returned. If the ovector is too small to hold all the captured substring offsets, - as much as possible is filled in, and the function returns a value of - zero. If captured substrings are not of interest, pcre2_match() may be + as much as possible is filled in, and the function returns a value of + zero. If captured substrings are not of interest, pcre2_match() may be called with a match data block whose ovector is of minimum length (that is, one pair). - It is possible for capturing subpattern number n+1 to match some part + It is possible for capturing subpattern number n+1 to match some part of the subject when subpattern n has not been used at all. For example, - if the string "abc" is matched against the pattern (a|(z))(bc) the + if the string "abc" is matched against the pattern (a|(z))(bc) the return from the function is 4, and subpatterns 1 and 3 are matched, but - 2 is not. When this happens, both values in the offset pairs corre- + 2 is not. When this happens, both values in the offset pairs corre- sponding to unused subpatterns are set to PCRE2_UNSET. - Offset values that correspond to unused subpatterns at the end of the - expression are also set to PCRE2_UNSET. For example, if the string + Offset values that correspond to unused subpatterns at the end of the + expression are also set to PCRE2_UNSET. For example, if the string "abc" is matched against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 - are not matched. The return from the function is 2, because the high- + are not matched. The return from the function is 2, because the high- est used capturing subpattern number is 1. The offsets for for the sec- - ond and third capturing subpatterns (assuming the vector is large + ond and third capturing subpatterns (assuming the vector is large enough, of course) are set to PCRE2_UNSET. Elements in the ovector that do not correspond to capturing parentheses in the pattern are never changed. That is, if a pattern contains n cap- turing parentheses, no more than ovector[0] to ovector[2n+1] are set by - pcre2_match(). The other elements retain whatever values they previ- + pcre2_match(). The other elements retain whatever values they previ- ously had. @@ -2466,56 +2473,56 @@ OTHER INFORMATION ABOUT A MATCH PCRE2_SIZE pcre2_get_startchar(pcre2_match_data *match_data); - As well as the offsets in the ovector, other information about a match - is retained in the match data block and can be retrieved by the above - functions in appropriate circumstances. If they are called at other + As well as the offsets in the ovector, other information about a match + is retained in the match data block and can be retrieved by the above + functions in appropriate circumstances. If they are called at other times, the result is undefined. - After a successful match, a partial match (PCRE2_ERROR_PARTIAL), or a - failure to match (PCRE2_ERROR_NOMATCH), a (*MARK) name may be avail- - able, and pcre2_get_mark() can be called. It returns a pointer to the - zero-terminated name, which is within the compiled pattern. Otherwise - NULL is returned. The length of the (*MARK) name (excluding the termi- - nating zero) is stored in the code unit that preceeds the name. You - should use this instead of relying on the terminating zero if the + After a successful match, a partial match (PCRE2_ERROR_PARTIAL), or a + failure to match (PCRE2_ERROR_NOMATCH), a (*MARK) name may be avail- + able, and pcre2_get_mark() can be called. It returns a pointer to the + zero-terminated name, which is within the compiled pattern. Otherwise + NULL is returned. The length of the (*MARK) name (excluding the termi- + nating zero) is stored in the code unit that preceeds the name. You + should use this instead of relying on the terminating zero if the (*MARK) name might contain a binary zero. After a successful match, the (*MARK) name that is returned is the last - one encountered on the matching path through the pattern. After a "no - match" or a partial match, the last encountered (*MARK) name is + one encountered on the matching path through the pattern. After a "no + match" or a partial match, the last encountered (*MARK) name is returned. For example, consider this pattern: ^(*MARK:A)((*MARK:B)a|b)c - When it matches "bc", the returned mark is A. The B mark is "seen" in - the first branch of the group, but it is not on the matching path. On - the other hand, when this pattern fails to match "bx", the returned + When it matches "bc", the returned mark is A. The B mark is "seen" in + the first branch of the group, but it is not on the matching path. On + the other hand, when this pattern fails to match "bx", the returned mark is B. - After a successful match, a partial match, or one of the invalid UTF - errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can + After a successful match, a partial match, or one of the invalid UTF + errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can be called. After a successful or partial match it returns the code unit - offset of the character at which the match started. For a non-partial - match, this can be different to the value of ovector[0] if the pattern - contains the \K escape sequence. After a partial match, however, this - value is always the same as ovector[0] because \K does not affect the + offset of the character at which the match started. For a non-partial + match, this can be different to the value of ovector[0] if the pattern + contains the \K escape sequence. After a partial match, however, this + value is always the same as ovector[0] because \K does not affect the result of a partial match. - After a UTF check failure, pcre2_get_startchar() can be used to obtain + After a UTF check failure, pcre2_get_startchar() can be used to obtain the code unit offset of the invalid UTF character. Details are given in the pcre2unicode page. ERROR RETURNS FROM pcre2_match() - If pcre2_match() fails, it returns a negative number. This can be con- - verted to a text string by calling the pcre2_get_error_message() func- - tion (see "Obtaining a textual error message" below). Negative error - codes are also returned by other functions, and are documented with - them. The codes are given names in the header file. If UTF checking is + If pcre2_match() fails, it returns a negative number. This can be con- + verted to a text string by calling the pcre2_get_error_message() func- + tion (see "Obtaining a textual error message" below). Negative error + codes are also returned by other functions, and are documented with + them. The codes are given names in the header file. If UTF checking is in force and an invalid UTF subject string is detected, one of a number - of UTF-specific negative error codes is returned. Details are given in - the pcre2unicode page. The following are the other errors that may be + of UTF-specific negative error codes is returned. Details are given in + the pcre2unicode page. The following are the other errors that may be returned by pcre2_match(): PCRE2_ERROR_NOMATCH @@ -2524,20 +2531,20 @@ ERROR RETURNS FROM pcre2_match() PCRE2_ERROR_PARTIAL - The subject string did not match, but it did match partially. See the + The subject string did not match, but it did match partially. See the pcre2partial documentation for details of partial matching. PCRE2_ERROR_BADMAGIC PCRE2 stores a 4-byte "magic number" at the start of the compiled code, - to catch the case when it is passed a junk pointer. This is the error + to catch the case when it is passed a junk pointer. This is the error that is returned when the magic number is not present. PCRE2_ERROR_BADMODE - This error is given when a compiled pattern is passed to a function in - a library of a different code unit width, for example, a pattern com- - piled by the 8-bit library is passed to a 16-bit or 32-bit library + This error is given when a compiled pattern is passed to a function in + a library of a different code unit width, for example, a pattern com- + piled by the 8-bit library is passed to a 16-bit or 32-bit library function. PCRE2_ERROR_BADOFFSET @@ -2551,15 +2558,15 @@ ERROR RETURNS FROM pcre2_match() PCRE2_ERROR_BADUTFOFFSET The UTF code unit sequence that was passed as a subject was checked and - found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the - value of startoffset did not point to the beginning of a UTF character + found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the + value of startoffset did not point to the beginning of a UTF character or the end of the subject. PCRE2_ERROR_CALLOUT - This error is never generated by pcre2_match() itself. It is provided - for use by callout functions that want to cause pcre2_match() or - pcre2_callout_enumerate() to return a distinctive error code. See the + This error is never generated by pcre2_match() itself. It is provided + for use by callout functions that want to cause pcre2_match() or + pcre2_callout_enumerate() to return a distinctive error code. See the pcre2callout documentation for details. PCRE2_ERROR_DEPTHLIMIT @@ -2568,14 +2575,14 @@ ERROR RETURNS FROM pcre2_match() PCRE2_ERROR_INTERNAL - An unexpected internal error has occurred. This error could be caused + An unexpected internal error has occurred. This error could be caused by a bug in PCRE2 or by overwriting of the compiled pattern. PCRE2_ERROR_JIT_STACKLIMIT - This error is returned when a pattern that was successfully studied - using JIT is being matched, but the memory available for the just-in- - time processing stack is not large enough. See the pcre2jit documenta- + This error is returned when a pattern that was successfully studied + using JIT is being matched, but the memory available for the just-in- + time processing stack is not large enough. See the pcre2jit documenta- tion for more details. PCRE2_ERROR_MATCHLIMIT @@ -2584,10 +2591,10 @@ ERROR RETURNS FROM pcre2_match() PCRE2_ERROR_NOMEMORY - If a pattern contains many nested backtracking points, heap memory is - used to remember them. This error is given when the memory allocation - function (default or custom) fails. Note that a different error, - PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds + If a pattern contains many nested backtracking points, heap memory is + used to remember them. This error is given when the memory allocation + function (default or custom) fails. Note that a different error, + PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds the heap limit. PCRE2_ERROR_NULL @@ -2596,12 +2603,12 @@ ERROR RETURNS FROM pcre2_match() PCRE2_ERROR_RECURSELOOP - This error is returned when pcre2_match() detects a recursion loop - within the pattern. Specifically, it means that either the whole pat- + This error is returned when pcre2_match() detects a recursion loop + within the pattern. Specifically, it means that either the whole pat- tern or a subpattern has been called recursively for the second time at - the same position in the subject string. Some simple patterns that - might do this are detected and faulted at compile time, but more com- - plicated cases, in particular mutual recursions between two different + the same position in the subject string. Some simple patterns that + might do this are detected and faulted at compile time, but more com- + plicated cases, in particular mutual recursions between two different subpatterns, cannot be detected until matching is attempted. @@ -2610,20 +2617,20 @@ OBTAINING A TEXTUAL ERROR MESSAGE int pcre2_get_error_message(int errorcode, PCRE2_UCHAR *buffer, PCRE2_SIZE bufflen); - A text message for an error code from any PCRE2 function (compile, - match, or auxiliary) can be obtained by calling pcre2_get_error_mes- - sage(). The code is passed as the first argument, with the remaining - two arguments specifying a code unit buffer and its length in code - units, into which the text message is placed. The message is returned - in code units of the appropriate width for the library that is being + A text message for an error code from any PCRE2 function (compile, + match, or auxiliary) can be obtained by calling pcre2_get_error_mes- + sage(). The code is passed as the first argument, with the remaining + two arguments specifying a code unit buffer and its length in code + units, into which the text message is placed. The message is returned + in code units of the appropriate width for the library that is being used. - The returned message is terminated with a trailing zero, and the func- - tion returns the number of code units used, excluding the trailing + The returned message is terminated with a trailing zero, and the func- + tion returns the number of code units used, excluding the trailing zero. If the error number is unknown, the negative error code - PCRE2_ERROR_BADDATA is returned. If the buffer is too small, the mes- - sage is truncated (but still with a trailing zero), and the negative - error code PCRE2_ERROR_NOMEMORY is returned. None of the messages are + PCRE2_ERROR_BADDATA is returned. If the buffer is too small, the mes- + sage is truncated (but still with a trailing zero), and the negative + error code PCRE2_ERROR_NOMEMORY is returned. None of the messages are very long; a buffer size of 120 code units is ample. @@ -2642,39 +2649,39 @@ EXTRACTING CAPTURED SUBSTRINGS BY NUMBER void pcre2_substring_free(PCRE2_UCHAR *buffer); - Captured substrings can be accessed directly by using the ovector as + Captured substrings can be accessed directly by using the ovector as described above. For convenience, auxiliary functions are provided for - extracting captured substrings as new, separate, zero-terminated + extracting captured substrings as new, separate, zero-terminated strings. A substring that contains a binary zero is correctly extracted - and has a further zero added on the end, but the result is not, of + and has a further zero added on the end, but the result is not, of course, a C string. The functions in this section identify substrings by number. The number zero refers to the entire matched substring, with higher numbers refer- - ring to substrings captured by parenthesized groups. After a partial - match, only substring zero is available. An attempt to extract any - other substring gives the error PCRE2_ERROR_PARTIAL. The next section + ring to substrings captured by parenthesized groups. After a partial + match, only substring zero is available. An attempt to extract any + other substring gives the error PCRE2_ERROR_PARTIAL. The next section describes similar functions for extracting captured substrings by name. - If a pattern uses the \K escape sequence within a positive assertion, + If a pattern uses the \K escape sequence within a positive assertion, the reported start of a successful match can be greater than the end of - the match. For example, if the pattern (?=ab\K) is matched against - "ab", the start and end offset values for the match are 2 and 0. In - this situation, calling these functions with a zero substring number + the match. For example, if the pattern (?=ab\K) is matched against + "ab", the start and end offset values for the match are 2 and 0. In + this situation, calling these functions with a zero substring number extracts a zero-length empty string. - You can find the length in code units of a captured substring without - extracting it by calling pcre2_substring_length_bynumber(). The first - argument is a pointer to the match data block, the second is the group - number, and the third is a pointer to a variable into which the length - is placed. If you just want to know whether or not the substring has + You can find the length in code units of a captured substring without + extracting it by calling pcre2_substring_length_bynumber(). The first + argument is a pointer to the match data block, the second is the group + number, and the third is a pointer to a variable into which the length + is placed. If you just want to know whether or not the substring has been captured, you can pass the third argument as NULL. - The pcre2_substring_copy_bynumber() function copies a captured sub- - string into a supplied buffer, whereas pcre2_substring_get_bynumber() - copies it into new memory, obtained using the same memory allocation - function that was used for the match data block. The first two argu- - ments of these functions are a pointer to the match data block and a + The pcre2_substring_copy_bynumber() function copies a captured sub- + string into a supplied buffer, whereas pcre2_substring_get_bynumber() + copies it into new memory, obtained using the same memory allocation + function that was used for the match data block. The first two argu- + ments of these functions are a pointer to the match data block and a capturing group number. The final arguments of pcre2_substring_copy_bynumber() are a pointer to @@ -2683,25 +2690,25 @@ EXTRACTING CAPTURED SUBSTRINGS BY NUMBER for the extracted substring, excluding the terminating zero. For pcre2_substring_get_bynumber() the third and fourth arguments point - to variables that are updated with a pointer to the new memory and the - number of code units that comprise the substring, again excluding the - terminating zero. When the substring is no longer needed, the memory + to variables that are updated with a pointer to the new memory and the + number of code units that comprise the substring, again excluding the + terminating zero. When the substring is no longer needed, the memory should be freed by calling pcre2_substring_free(). - The return value from all these functions is zero for success, or a - negative error code. If the pattern match failed, the match failure - code is returned. If a substring number greater than zero is used - after a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible + The return value from all these functions is zero for success, or a + negative error code. If the pattern match failed, the match failure + code is returned. If a substring number greater than zero is used + after a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible error codes are: PCRE2_ERROR_NOMEMORY - The buffer was too small for pcre2_substring_copy_bynumber(), or the + The buffer was too small for pcre2_substring_copy_bynumber(), or the attempt to get memory failed for pcre2_substring_get_bynumber(). PCRE2_ERROR_NOSUBSTRING - There is no substring with that number in the pattern, that is, the + There is no substring with that number in the pattern, that is, the number is greater than the number of capturing parentheses. PCRE2_ERROR_UNAVAILABLE @@ -2712,8 +2719,8 @@ EXTRACTING CAPTURED SUBSTRINGS BY NUMBER PCRE2_ERROR_UNSET - The substring did not participate in the match. For example, if the - pattern is (abc)|(def) and the subject is "def", and the ovector con- + The substring did not participate in the match. For example, if the + pattern is (abc)|(def) and the subject is "def", and the ovector con- tains at least two capturing slots, substring number 1 is unset. @@ -2724,32 +2731,32 @@ EXTRACTING A LIST OF ALL CAPTURED SUBSTRINGS void pcre2_substring_list_free(PCRE2_SPTR *list); - The pcre2_substring_list_get() function extracts all available sub- - strings and builds a list of pointers to them. It also (optionally) - builds a second list that contains their lengths (in code units), + The pcre2_substring_list_get() function extracts all available sub- + strings and builds a list of pointers to them. It also (optionally) + builds a second list that contains their lengths (in code units), excluding a terminating zero that is added to each of them. All this is done in a single block of memory that is obtained using the same memory allocation function that was used to get the match data block. - This function must be called only after a successful match. If called + This function must be called only after a successful match. If called after a partial match, the error code PCRE2_ERROR_PARTIAL is returned. - The address of the memory block is returned via listptr, which is also + The address of the memory block is returned via listptr, which is also the start of the list of string pointers. The end of the list is marked - by a NULL pointer. The address of the list of lengths is returned via - lengthsptr. If your strings do not contain binary zeros and you do not + by a NULL pointer. The address of the list of lengths is returned via + lengthsptr. If your strings do not contain binary zeros and you do not therefore need the lengths, you may supply NULL as the lengthsptr argu- - ment to disable the creation of a list of lengths. The yield of the - function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem- - ory block could not be obtained. When the list is no longer needed, it + ment to disable the creation of a list of lengths. The yield of the + function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem- + ory block could not be obtained. When the list is no longer needed, it should be freed by calling pcre2_substring_list_free(). If this function encounters a substring that is unset, which can happen - when capturing subpattern number n+1 matches some part of the subject, - but subpattern n has not been used at all, it returns an empty string. - This can be distinguished from a genuine zero-length substring by + when capturing subpattern number n+1 matches some part of the subject, + but subpattern n has not been used at all, it returns an empty string. + This can be distinguished from a genuine zero-length substring by inspecting the appropriate offset in the ovector, which contain - PCRE2_UNSET for unset substrings, or by calling pcre2_sub- + PCRE2_UNSET for unset substrings, or by calling pcre2_sub- string_length_bynumber(). @@ -2769,39 +2776,39 @@ EXTRACTING CAPTURED SUBSTRINGS BY NAME void pcre2_substring_free(PCRE2_UCHAR *buffer); - To extract a substring by name, you first have to find associated num- + To extract a substring by name, you first have to find associated num- ber. For example, for this pattern: (a+)b(?<xxx>\d+)... the number of the subpattern called "xxx" is 2. If the name is known to - be unique (PCRE2_DUPNAMES was not set), you can find the number from + be unique (PCRE2_DUPNAMES was not set), you can find the number from the name by calling pcre2_substring_number_from_name(). The first argu- - ment is the compiled pattern, and the second is the name. The yield of + ment is the compiled pattern, and the second is the name. The yield of the function is the subpattern number, PCRE2_ERROR_NOSUBSTRING if there - is no subpattern of that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if - there is more than one subpattern of that name. Given the number, you - can extract the substring directly from the ovector, or use one of the + is no subpattern of that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if + there is more than one subpattern of that name. Given the number, you + can extract the substring directly from the ovector, or use one of the "bynumber" functions described above. - For convenience, there are also "byname" functions that correspond to - the "bynumber" functions, the only difference being that the second - argument is a name instead of a number. If PCRE2_DUPNAMES is set and + For convenience, there are also "byname" functions that correspond to + the "bynumber" functions, the only difference being that the second + argument is a name instead of a number. If PCRE2_DUPNAMES is set and there are duplicate names, these functions scan all the groups with the given name, and return the first named string that is set. - If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is - returned. If all groups with the name have numbers that are greater - than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is - returned. If there is at least one group with a slot in the ovector, + If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is + returned. If all groups with the name have numbers that are greater + than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is + returned. If there is at least one group with a slot in the ovector, but no group is found to be set, PCRE2_ERROR_UNSET is returned. Warning: If the pattern uses the (?| feature to set up multiple subpat- - terns with the same number, as described in the section on duplicate - subpattern numbers in the pcre2pattern page, you cannot use names to - distinguish the different subpatterns, because names are not included - in the compiled code. The matching process uses only numbers. For this - reason, the use of different names for subpatterns of the same number + terns with the same number, as described in the section on duplicate + subpattern numbers in the pcre2pattern page, you cannot use names to + distinguish the different subpatterns, because names are not included + in the compiled code. The matching process uses only numbers. For this + reason, the use of different names for subpatterns of the same number causes an error at compile time. @@ -2814,52 +2821,52 @@ CREATING A NEW STRING WITH SUBSTITUTIONS PCRE2_SIZE rlength, PCRE2_UCHAR *outputbufferP, PCRE2_SIZE *outlengthptr); - This function calls pcre2_match() and then makes a copy of the subject - string in outputbuffer, replacing the part that was matched with the - replacement string, whose length is supplied in rlength. This can be + This function calls pcre2_match() and then makes a copy of the subject + string in outputbuffer, replacing the part that was matched with the + replacement string, whose length is supplied in rlength. This can be given as PCRE2_ZERO_TERMINATED for a zero-terminated string. Matches in - which a \K item in a lookahead in the pattern causes the match to end + which a \K item in a lookahead in the pattern causes the match to end before it starts are not supported, and give rise to an error return. - The first seven arguments of pcre2_substitute() are the same as for + The first seven arguments of pcre2_substitute() are the same as for pcre2_match(), except that the partial matching options are not permit- - ted, and match_data may be passed as NULL, in which case a match data - block is obtained and freed within this function, using memory manage- - ment functions from the match context, if provided, or else those that + ted, and match_data may be passed as NULL, in which case a match data + block is obtained and freed within this function, using memory manage- + ment functions from the match context, if provided, or else those that were used to allocate memory for the compiled code. - The outlengthptr argument must point to a variable that contains the - length, in code units, of the output buffer. If the function is suc- - cessful, the value is updated to contain the length of the new string, + The outlengthptr argument must point to a variable that contains the + length, in code units, of the output buffer. If the function is suc- + cessful, the value is updated to contain the length of the new string, excluding the trailing zero that is automatically added. - If the function is not successful, the value set via outlengthptr - depends on the type of error. For syntax errors in the replacement - string, the value is the offset in the replacement string where the - error was detected. For other errors, the value is PCRE2_UNSET by - default. This includes the case of the output buffer being too small, - unless PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which - case the value is the minimum length needed, including space for the - trailing zero. Note that in order to compute the required length, - pcre2_substitute() has to simulate all the matching and copying, + If the function is not successful, the value set via outlengthptr + depends on the type of error. For syntax errors in the replacement + string, the value is the offset in the replacement string where the + error was detected. For other errors, the value is PCRE2_UNSET by + default. This includes the case of the output buffer being too small, + unless PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which + case the value is the minimum length needed, including space for the + trailing zero. Note that in order to compute the required length, + pcre2_substitute() has to simulate all the matching and copying, instead of giving an error return as soon as the buffer overflows. Note also that the length is in code units, not bytes. - In the replacement string, which is interpreted as a UTF string in UTF - mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK + In the replacement string, which is interpreted as a UTF string in UTF + mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK option is set, a dollar character is an escape character that can spec- - ify the insertion of characters from capturing groups or (*MARK) items + ify the insertion of characters from capturing groups or (*MARK) items in the pattern. The following forms are always recognized: $$ insert a dollar character $<n> or ${<n>} insert the contents of group <n> $*MARK or ${*MARK} insert the name of the last (*MARK) encountered - Either a group number or a group name can be given for <n>. Curly - brackets are required only if the following character would be inter- + Either a group number or a group name can be given for <n>. Curly + brackets are required only if the following character would be inter- preted as part of the number or name. The number may be zero to include - the entire matched string. For example, if the pattern a(b)c is - matched with "=abc=" and the replacement string "+$1$0$1+", the result + the entire matched string. For example, if the pattern a(b)c is + matched with "=abc=" and the replacement string "+$1$0$1+", the result is "=+babcb+=". The facility for inserting a (*MARK) name can be used to perform simple @@ -2869,92 +2876,92 @@ CREATING A NEW STRING WITH SUBSTITUTIONS apple lemon 2: pear orange - As well as the usual options for pcre2_match(), a number of additional + As well as the usual options for pcre2_match(), a number of additional options can be set in the options argument. PCRE2_SUBSTITUTE_GLOBAL causes the function to iterate over the subject - string, replacing every matching substring. If this is not set, only - the first matching substring is replaced. If any matched substring has - zero length, after the substitution has happened, an attempt to find a - non-empty match at the same position is performed. If this is not suc- - cessful, the current position is advanced by one character except when - CRLF is a valid newline sequence and the next two characters are CR, + string, replacing every matching substring. If this is not set, only + the first matching substring is replaced. If any matched substring has + zero length, after the substitution has happened, an attempt to find a + non-empty match at the same position is performed. If this is not suc- + cessful, the current position is advanced by one character except when + CRLF is a valid newline sequence and the next two characters are CR, LF. In this case, the current position is advanced by two characters. - PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output + PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output buffer is too small. The default action is to return PCRE2_ERROR_NOMEM- - ORY immediately. If this option is set, however, pcre2_substitute() + ORY immediately. If this option is set, however, pcre2_substitute() continues to go through the motions of matching and substituting (with- - out, of course, writing anything) in order to compute the size of buf- - fer that is needed. This value is passed back via the outlengthptr - variable, with the result of the function still being + out, of course, writing anything) in order to compute the size of buf- + fer that is needed. This value is passed back via the outlengthptr + variable, with the result of the function still being PCRE2_ERROR_NOMEMORY. - Passing a buffer size of zero is a permitted way of finding out how - much memory is needed for given substitution. However, this does mean + Passing a buffer size of zero is a permitted way of finding out how + much memory is needed for given substitution. However, this does mean that the entire operation is carried out twice. Depending on the appli- - cation, it may be more efficient to allocate a large buffer and free - the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER- + cation, it may be more efficient to allocate a large buffer and free + the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER- FLOW_LENGTH. - PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capturing groups - that do not appear in the pattern to be treated as unset groups. This - option should be used with care, because it means that a typo in a - group name or number no longer causes the PCRE2_ERROR_NOSUBSTRING + PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capturing groups + that do not appear in the pattern to be treated as unset groups. This + option should be used with care, because it means that a typo in a + group name or number no longer causes the PCRE2_ERROR_NOSUBSTRING error. - PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capturing groups (including + PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capturing groups (including unknown groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be - treated as empty strings when inserted as described above. If this - option is not set, an attempt to insert an unset group causes the - PCRE2_ERROR_UNSET error. This option does not influence the extended + treated as empty strings when inserted as described above. If this + option is not set, an attempt to insert an unset group causes the + PCRE2_ERROR_UNSET error. This option does not influence the extended substitution syntax described below. - PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the - replacement string. Without this option, only the dollar character is - special, and only the group insertion forms listed above are valid. + PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the + replacement string. Without this option, only the dollar character is + special, and only the group insertion forms listed above are valid. When PCRE2_SUBSTITUTE_EXTENDED is set, two things change: - Firstly, backslash in a replacement string is interpreted as an escape + Firstly, backslash in a replacement string is interpreted as an escape character. The usual forms such as \n or \x{ddd} can be used to specify - particular character codes, and backslash followed by any non-alphanu- - meric character quotes that character. Extended quoting can be coded + particular character codes, and backslash followed by any non-alphanu- + meric character quotes that character. Extended quoting can be coded using \Q...\E, exactly as in pattern strings. - There are also four escape sequences for forcing the case of inserted - letters. The insertion mechanism has three states: no case forcing, + There are also four escape sequences for forcing the case of inserted + letters. The insertion mechanism has three states: no case forcing, force upper case, and force lower case. The escape sequences change the current state: \U and \L change to upper or lower case forcing, respec- - tively, and \E (when not terminating a \Q quoted sequence) reverts to - no case forcing. The sequences \u and \l force the next character (if - it is a letter) to upper or lower case, respectively, and then the + tively, and \E (when not terminating a \Q quoted sequence) reverts to + no case forcing. The sequences \u and \l force the next character (if + it is a letter) to upper or lower case, respectively, and then the state automatically reverts to no case forcing. Case forcing applies to all inserted characters, including those from captured groups and let- ters within \Q...\E quoted sequences. Note that case forcing sequences such as \U...\E do not nest. For exam- - ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final + ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final \E has no effect. - The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more - flexibility to group substitution. The syntax is similar to that used + The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more + flexibility to group substitution. The syntax is similar to that used by Bash: ${<n>:-<string>} ${<n>:+<string1>:<string2>} - As before, <n> may be a group number or a name. The first form speci- - fies a default value. If group <n> is set, its value is inserted; if - not, <string> is expanded and the result inserted. The second form - specifies strings that are expanded and inserted when group <n> is set - or unset, respectively. The first form is just a convenient shorthand + As before, <n> may be a group number or a name. The first form speci- + fies a default value. If group <n> is set, its value is inserted; if + not, <string> is expanded and the result inserted. The second form + specifies strings that are expanded and inserted when group <n> is set + or unset, respectively. The first form is just a convenient shorthand for ${<n>:+${<n>}:<string>} - Backslash can be used to escape colons and closing curly brackets in - the replacement strings. A change of the case forcing state within a - replacement string remains in force afterwards, as shown in this + Backslash can be used to escape colons and closing curly brackets in + the replacement strings. A change of the case forcing state within a + replacement string remains in force afterwards, as shown in this pcre2test example: /(some)?(body)/substitute_extended,replace=${1:+\U:\L}HeLLo @@ -2963,41 +2970,41 @@ CREATING A NEW STRING WITH SUBSTITUTIONS somebody 1: HELLO - The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended - substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause + The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended + substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause unknown groups in the extended syntax forms to be treated as unset. - If successful, pcre2_substitute() returns the number of replacements + If successful, pcre2_substitute() returns the number of replacements that were made. This may be zero if no matches were found, and is never greater than 1 unless PCRE2_SUBSTITUTE_GLOBAL is set. In the event of an error, a negative error code is returned. Except for - PCRE2_ERROR_NOMATCH (which is never returned), errors from + PCRE2_ERROR_NOMATCH (which is never returned), errors from pcre2_match() are passed straight back. PCRE2_ERROR_NOSUBSTRING is returned for a non-existent substring inser- tion, unless PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set. PCRE2_ERROR_UNSET is returned for an unset substring insertion (includ- - ing an unknown substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) + ing an unknown substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) when the simple (non-extended) syntax is used and PCRE2_SUBSTI- TUTE_UNSET_EMPTY is not set. - PCRE2_ERROR_NOMEMORY is returned if the output buffer is not big + PCRE2_ERROR_NOMEMORY is returned if the output buffer is not big enough. If the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set, the size - of buffer that is needed is returned via outlengthptr. Note that this + of buffer that is needed is returned via outlengthptr. Note that this does not happen by default. - PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in + PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in the replacement string, with more particular errors being - PCRE2_ERROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REP- - MISSING_BRACE (closing curly bracket not found), PCRE2_BADSUBSTITUTION - (syntax error in extended group substitution), and PCRE2_BADSUBPATTERN - (the pattern match ended before it started, which can happen if \K is + PCRE2_ERROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REP- + MISSING_BRACE (closing curly bracket not found), PCRE2_BADSUBSTITUTION + (syntax error in extended group substitution), and PCRE2_BADSUBPATTERN + (the pattern match ended before it started, which can happen if \K is used in an assertion). As for all PCRE2 errors, a text message that describes the error can be - obtained by calling the pcre2_get_error_message() function (see + obtained by calling the pcre2_get_error_message() function (see "Obtaining a textual error message" above). @@ -3006,56 +3013,56 @@ DUPLICATE SUBPATTERN NAMES int pcre2_substring_nametable_scan(const pcre2_code *code, PCRE2_SPTR name, PCRE2_SPTR *first, PCRE2_SPTR *last); - When a pattern is compiled with the PCRE2_DUPNAMES option, names for - subpatterns are not required to be unique. Duplicate names are always - allowed for subpatterns with the same number, created by using the (?| - feature. Indeed, if such subpatterns are named, they are required to + When a pattern is compiled with the PCRE2_DUPNAMES option, names for + subpatterns are not required to be unique. Duplicate names are always + allowed for subpatterns with the same number, created by using the (?| + feature. Indeed, if such subpatterns are named, they are required to use the same names. Normally, patterns with duplicate names are such that in any one match, - only one of the named subpatterns participates. An example is shown in + only one of the named subpatterns participates. An example is shown in the pcre2pattern documentation. - When duplicates are present, pcre2_substring_copy_byname() and - pcre2_substring_get_byname() return the first substring corresponding - to the given name that is set. Only if none are set is - PCRE2_ERROR_UNSET is returned. The pcre2_substring_number_from_name() + When duplicates are present, pcre2_substring_copy_byname() and + pcre2_substring_get_byname() return the first substring corresponding + to the given name that is set. Only if none are set is + PCRE2_ERROR_UNSET is returned. The pcre2_substring_number_from_name() function returns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are duplicate names. - If you want to get full details of all captured substrings for a given - name, you must use the pcre2_substring_nametable_scan() function. The - first argument is the compiled pattern, and the second is the name. If - the third and fourth arguments are NULL, the function returns a group + If you want to get full details of all captured substrings for a given + name, you must use the pcre2_substring_nametable_scan() function. The + first argument is the compiled pattern, and the second is the name. If + the third and fourth arguments are NULL, the function returns a group number for a unique name, or PCRE2_ERROR_NOUNIQUESUBSTRING otherwise. When the third and fourth arguments are not NULL, they must be pointers - to variables that are updated by the function. After it has run, they + to variables that are updated by the function. After it has run, they point to the first and last entries in the name-to-number table for the - given name, and the function returns the length of each entry in code - units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are + given name, and the function returns the length of each entry in code + units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are no entries for the given name. The format of the name table is described above in the section entitled - Information about a pattern. Given all the relevant entries for the - name, you can extract each of their numbers, and hence the captured + Information about a pattern. Given all the relevant entries for the + name, you can extract each of their numbers, and hence the captured data. FINDING ALL POSSIBLE MATCHES AT ONE POSITION - The traditional matching function uses a similar algorithm to Perl, - which stops when it finds the first match at a given point in the sub- + The traditional matching function uses a similar algorithm to Perl, + which stops when it finds the first match at a given point in the sub- ject. If you want to find all possible matches, or the longest possible - match at a given position, consider using the alternative matching - function (see below) instead. If you cannot use the alternative func- + match at a given position, consider using the alternative matching + function (see below) instead. If you cannot use the alternative func- tion, you can kludge it up by making use of the callout facility, which is described in the pcre2callout documentation. What you have to do is to insert a callout right at the end of the pat- - tern. When your callout function is called, extract and save the cur- - rent matched substring. Then return 1, which forces pcre2_match() to - backtrack and try other alternatives. Ultimately, when it runs out of + tern. When your callout function is called, extract and save the cur- + rent matched substring. Then return 1, which forces pcre2_match() to + backtrack and try other alternatives. Ultimately, when it runs out of matches, pcre2_match() will yield PCRE2_ERROR_NOMATCH. @@ -3067,26 +3074,26 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION pcre2_match_context *mcontext, int *workspace, PCRE2_SIZE wscount); - The function pcre2_dfa_match() is called to match a subject string - against a compiled pattern, using a matching algorithm that scans the + The function pcre2_dfa_match() is called to match a subject string + against a compiled pattern, using a matching algorithm that scans the subject string just once (not counting lookaround assertions), and does - not backtrack. This has different characteristics to the normal algo- - rithm, and is not compatible with Perl. Some of the features of PCRE2 - patterns are not supported. Nevertheless, there are times when this - kind of matching can be useful. For a discussion of the two matching + not backtrack. This has different characteristics to the normal algo- + rithm, and is not compatible with Perl. Some of the features of PCRE2 + patterns are not supported. Nevertheless, there are times when this + kind of matching can be useful. For a discussion of the two matching algorithms, and a list of features that pcre2_dfa_match() does not sup- port, see the pcre2matching documentation. - The arguments for the pcre2_dfa_match() function are the same as for + The arguments for the pcre2_dfa_match() function are the same as for pcre2_match(), plus two extras. The ovector within the match data block is used in a different way, and this is described below. The other com- - mon arguments are used in the same way as for pcre2_match(), so their + mon arguments are used in the same way as for pcre2_match(), so their description is not repeated here. - The two additional arguments provide workspace for the function. The - workspace vector should contain at least 20 elements. It is used for + The two additional arguments provide workspace for the function. The + workspace vector should contain at least 20 elements. It is used for keeping track of multiple paths through the pattern tree. More - workspace is needed for patterns and subjects where there are a lot of + workspace is needed for patterns and subjects where there are a lot of potential matches. Here is an example of a simple call to pcre2_dfa_match(): @@ -3106,45 +3113,45 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION Option bits for pcre_dfa_match() - The unused bits of the options argument for pcre2_dfa_match() must be - zero. The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDAN- - CHORED, PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY, + The unused bits of the options argument for pcre2_dfa_match() must be + zero. The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDAN- + CHORED, PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART, PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, - PCRE2_PARTIAL_SOFT, PCRE2_DFA_SHORTEST, and PCRE2_DFA_RESTART. All but - the last four of these are exactly the same as for pcre2_match(), so + PCRE2_PARTIAL_SOFT, PCRE2_DFA_SHORTEST, and PCRE2_DFA_RESTART. All but + the last four of these are exactly the same as for pcre2_match(), so their description is not repeated here. PCRE2_PARTIAL_HARD PCRE2_PARTIAL_SOFT - These have the same general effect as they do for pcre2_match(), but - the details are slightly different. When PCRE2_PARTIAL_HARD is set for - pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the + These have the same general effect as they do for pcre2_match(), but + the details are slightly different. When PCRE2_PARTIAL_HARD is set for + pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the subject is reached and there is still at least one matching possibility that requires additional characters. This happens even if some complete - matches have already been found. When PCRE2_PARTIAL_SOFT is set, the - return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL - if the end of the subject is reached, there have been no complete + matches have already been found. When PCRE2_PARTIAL_SOFT is set, the + return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL + if the end of the subject is reached, there have been no complete matches, but there is still at least one matching possibility. The por- - tion of the string that was inspected when the longest partial match + tion of the string that was inspected when the longest partial match was found is set as the first matching string in both cases. There is a - more detailed discussion of partial and multi-segment matching, with + more detailed discussion of partial and multi-segment matching, with examples, in the pcre2partial documentation. PCRE2_DFA_SHORTEST - Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to + Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to stop as soon as it has found one match. Because of the way the alterna- - tive algorithm works, this is necessarily the shortest possible match + tive algorithm works, this is necessarily the shortest possible match at the first possible matching point in the subject string. PCRE2_DFA_RESTART - When pcre2_dfa_match() returns a partial match, it is possible to call + When pcre2_dfa_match() returns a partial match, it is possible to call it again, with additional subject characters, and have it continue with the same match. The PCRE2_DFA_RESTART option requests this action; when - it is set, the workspace and wscount options must reference the same - vector as before because data about the match so far is left in them + it is set, the workspace and wscount options must reference the same + vector as before because data about the match so far is left in them after a partial match. There is more discussion of this facility in the pcre2partial documentation. @@ -3152,8 +3159,8 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION When pcre2_dfa_match() succeeds, it may have matched more than one sub- string in the subject. Note, however, that all the matches from one run - of the function start at the same point in the subject. The shorter - matches are all initial substrings of the longer matches. For example, + of the function start at the same point in the subject. The shorter + matches are all initial substrings of the longer matches. For example, if the pattern <.*> @@ -3168,17 +3175,17 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION <something> <something else> <something> - On success, the yield of the function is a number greater than zero, - which is the number of matched substrings. The offsets of the sub- - strings are returned in the ovector, and can be extracted by number in - the same way as for pcre2_match(), but the numbers bear no relation to - any capturing groups that may exist in the pattern, because DFA match- + On success, the yield of the function is a number greater than zero, + which is the number of matched substrings. The offsets of the sub- + strings are returned in the ovector, and can be extracted by number in + the same way as for pcre2_match(), but the numbers bear no relation to + any capturing groups that may exist in the pattern, because DFA match- ing does not support group capture. - Calls to the convenience functions that extract substrings by name - return the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used + Calls to the convenience functions that extract substrings by name + return the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used after a DFA match. The convenience functions that extract substrings by - number never return PCRE2_ERROR_NOSUBSTRING, and the meanings of some + number never return PCRE2_ERROR_NOSUBSTRING, and the meanings of some other errors are slightly different: PCRE2_ERROR_UNAVAILABLE @@ -3188,64 +3195,64 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION PCRE2_ERROR_UNSET - There is a slot in the ovector for this substring, but there were + There is a slot in the ovector for this substring, but there were insufficient matches to fill it. - The matched strings are stored in the ovector in reverse order of - length; that is, the longest matching string is first. If there were - too many matches to fit into the ovector, the yield of the function is + The matched strings are stored in the ovector in reverse order of + length; that is, the longest matching string is first. If there were + too many matches to fit into the ovector, the yield of the function is zero, and the vector is filled with the longest matches. - NOTE: PCRE2's "auto-possessification" optimization usually applies to - character repeats at the end of a pattern (as well as internally). For - example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA - matching, this means that only one possible match is found. If you - really do want multiple matches in such cases, either use an ungreedy - repeat auch as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when + NOTE: PCRE2's "auto-possessification" optimization usually applies to + character repeats at the end of a pattern (as well as internally). For + example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA + matching, this means that only one possible match is found. If you + really do want multiple matches in such cases, either use an ungreedy + repeat auch as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when compiling. Error returns from pcre2_dfa_match() The pcre2_dfa_match() function returns a negative number when it fails. - Many of the errors are the same as for pcre2_match(), as described + Many of the errors are the same as for pcre2_match(), as described above. There are in addition the following errors that are specific to pcre2_dfa_match(): PCRE2_ERROR_DFA_UITEM - This return is given if pcre2_dfa_match() encounters an item in the - pattern that it does not support, for instance, the use of \C in a UTF + This return is given if pcre2_dfa_match() encounters an item in the + pattern that it does not support, for instance, the use of \C in a UTF mode or a back reference. PCRE2_ERROR_DFA_UCOND - This return is given if pcre2_dfa_match() encounters a condition item - that uses a back reference for the condition, or a test for recursion + This return is given if pcre2_dfa_match() encounters a condition item + that uses a back reference for the condition, or a test for recursion in a specific group. These are not supported. PCRE2_ERROR_DFA_WSSIZE - This return is given if pcre2_dfa_match() runs out of space in the + This return is given if pcre2_dfa_match() runs out of space in the workspace vector. PCRE2_ERROR_DFA_RECURSE - When a recursive subpattern is processed, the matching function calls + When a recursive subpattern is processed, the matching function calls itself recursively, using private memory for the ovector and workspace. - This error is given if the internal ovector is not large enough. This + This error is given if the internal ovector is not large enough. This should be extremely rare, as a vector of size 1000 is used. PCRE2_ERROR_DFA_BADRESTART - When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option, - some plausibility checks are made on the contents of the workspace, - which should contain data about the previous partial match. If any of + When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option, + some plausibility checks are made on the contents of the workspace, + which should contain data about the previous partial match. If any of these checks fail, this error is given. SEE ALSO - pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3), + pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3), pcre2partial(3), pcre2posix(3), pcre2sample(3), pcre2unicode(3). @@ -3258,7 +3265,7 @@ AUTHOR REVISION - Last updated: 14 April 2017 + Last updated: 17 April 2017 Copyright (c) 1997-2017 University of Cambridge. ------------------------------------------------------------------------------ @@ -4363,19 +4370,16 @@ DIFFERENCES BETWEEN PCRE2 AND PERL at the start of a pattern that set overall options that cannot be changed within the pattern. - 18. The following new Perl 5.26 constructs are not yet supported in - PCRE2: - - (a) The Perl /a modifier restricts /d numbers to pure ascii, the new - /aa modifier restricts /i case-insensitive matching to pure ascii also, - ignoring unicode rules. This separation cannot be represented with - PCRE2_UTF. + 18. The Perl /a modifier restricts /d numbers to pure ascii, and the + /aa modifier restricts /i case-insensitive matching to pure ascii, + ignoring Unicode rules. This separation cannot be represented with + PCRE2_UCP. 19. Perl has different limits than PCRE2. See the pcre2limit documenta- tion for details. Perl went with 5.10 from recursion to iteration keep- ing the intermediate matches on the heap, which is ~10% slower but does - not fall into any stack-overflow limit. PCRE2 made a similar change at - release 10.30, and also has many build-time and run-time customizable + not fall into any stack-overflow limit. PCRE2 made a similar change at + release 10.30, and also has many build-time and run-time customizable limits. @@ -4388,7 +4392,7 @@ AUTHOR REVISION - Last updated: 17 April 2017 + Last updated: 18 April 2017 Copyright (c) 1997-2017 University of Cambridge. ------------------------------------------------------------------------------ @@ -6798,51 +6802,55 @@ VERTICAL BAR INTERNAL OPTION SETTING - The settings of the PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL, and - PCRE2_EXTENDED options (which are Perl-compatible) can be changed from - within the pattern by a sequence of Perl option letters enclosed - between "(?" and ")". The option letters are + The settings of the PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL, + PCRE2_EXTENDED, and PCRE2_EXTENDED_MORE options (which are Perl-compat- + ible) can be changed from within the pattern by a sequence of Perl + option letters enclosed between "(?" and ")". The option letters are i for PCRE2_CASELESS m for PCRE2_MULTILINE s for PCRE2_DOTALL x for PCRE2_EXTENDED + xx for PCRE2_EXTENDED_MORE For example, (?im) sets caseless, multiline matching. It is also possi- - ble to unset these options by preceding the letter with a hyphen, and a - combined setting and unsetting such as (?im-sx), which sets PCRE2_CASE- - LESS and PCRE2_MULTILINE while unsetting PCRE2_DOTALL and - PCRE2_EXTENDED, is also permitted. If a letter appears both before and - after the hyphen, the option is unset. An empty options setting "(?)" + ble to unset these options by preceding the letter with a hyphen. The + two "extended" options are not independent; unsetting either one can- + cels the effects of both of them. + + A combined setting and unsetting such as (?im-sx), which sets + PCRE2_CASELESS and PCRE2_MULTILINE while unsetting PCRE2_DOTALL and + PCRE2_EXTENDED, is also permitted. If a letter appears both before and + after the hyphen, the option is unset. An empty options setting "(?)" is allowed. Needless to say, it has no effect. - The PCRE2-specific options PCRE2_DUPNAMES and PCRE2_UNGREEDY can be - changed in the same way as the Perl-compatible options by using the + The PCRE2-specific options PCRE2_DUPNAMES and PCRE2_UNGREEDY can be + changed in the same way as the Perl-compatible options by using the characters J and U respectively. - When one of these option changes occurs at top level (that is, not - inside subpattern parentheses), the change applies to the remainder of - the pattern that follows. An option change within a subpattern (see - below for a description of subpatterns) affects only that part of the + When one of these option changes occurs at top level (that is, not + inside subpattern parentheses), the change applies to the remainder of + the pattern that follows. An option change within a subpattern (see + below for a description of subpatterns) affects only that part of the subpattern that follows it, so (a(?i)b)c - matches abc and aBc and no other strings (assuming PCRE2_CASELESS is - not used). By this means, options can be made to have different set- + matches abc and aBc and no other strings (assuming PCRE2_CASELESS is + not used). By this means, options can be made to have different set- tings in different parts of the pattern. Any changes made in one alter- native do carry on into subsequent branches within the same subpattern. For example, (a(?i)b|c) - matches "ab", "aB", "c", and "C", even though when matching "C" the - first branch is abandoned before the option setting. This is because - the effects of option settings happen at compile time. There would be + matches "ab", "aB", "c", and "C", even though when matching "C" the + first branch is abandoned before the option setting. This is because + the effects of option settings happen at compile time. There would be some very weird behaviour otherwise. - As a convenient shorthand, if any option settings are required at the - start of a non-capturing subpattern (see the next section), the option + As a convenient shorthand, if any option settings are required at the + start of a non-capturing subpattern (see the next section), the option letters may appear between the "?" and the ":". Thus the two patterns (?i:saturday|sunday) @@ -6850,14 +6858,14 @@ INTERNAL OPTION SETTING match exactly the same set of strings. - Note: There are other PCRE2-specific options that can be set by the + Note: There are other PCRE2-specific options that can be set by the application when the compiling function is called. The pattern can con- - tain special leading sequences such as (*CRLF) to override what the - application has set or what has been defaulted. Details are given in - the section entitled "Newline sequences" above. There are also the - (*UTF) and (*UCP) leading sequences that can be used to set UTF and - Unicode property modes; they are equivalent to setting the PCRE2_UTF - and PCRE2_UCP options, respectively. However, the application can set + tain special leading sequences such as (*CRLF) to override what the + application has set or what has been defaulted. Details are given in + the section entitled "Newline sequences" above. There are also the + (*UTF) and (*UCP) leading sequences that can be used to set UTF and + Unicode property modes; they are equivalent to setting the PCRE2_UTF + and PCRE2_UCP options, respectively. However, the application can set the PCRE2_NEVER_UTF and PCRE2_NEVER_UCP options, which lock out the use of the (*UTF) and (*UCP) sequences. @@ -6871,18 +6879,18 @@ SUBPATTERNS cat(aract|erpillar|) - matches "cataract", "caterpillar", or "cat". Without the parentheses, + matches "cataract", "caterpillar", or "cat". Without the parentheses, it would match "cataract", "erpillar" or an empty string. - 2. It sets up the subpattern as a capturing subpattern. This means + 2. It sets up the subpattern as a capturing subpattern. This means that, when the whole pattern matches, the portion of the subject string - that matched the subpattern is passed back to the caller, separately - from the portion that matched the whole pattern. (This applies only to - the traditional matching function; the DFA matching function does not + that matched the subpattern is passed back to the caller, separately + from the portion that matched the whole pattern. (This applies only to + the traditional matching function; the DFA matching function does not support capturing.) Opening parentheses are counted from left to right (starting from 1) to - obtain numbers for the capturing subpatterns. For example, if the + obtain numbers for the capturing subpatterns. For example, if the string "the red king" is matched against the pattern the ((red|white) (king|queen)) @@ -6890,12 +6898,12 @@ SUBPATTERNS the captured substrings are "red king", "red", and "king", and are num- bered 1, 2, and 3, respectively. - The fact that plain parentheses fulfil two functions is not always - helpful. There are often times when a grouping subpattern is required - without a capturing requirement. If an opening parenthesis is followed - by a question mark and a colon, the subpattern does not do any captur- - ing, and is not counted when computing the number of any subsequent - capturing subpatterns. For example, if the string "the white queen" is + The fact that plain parentheses fulfil two functions is not always + helpful. There are often times when a grouping subpattern is required + without a capturing requirement. If an opening parenthesis is followed + by a question mark and a colon, the subpattern does not do any captur- + ing, and is not counted when computing the number of any subsequent + capturing subpatterns. For example, if the string "the white queen" is matched against the pattern the ((?:red|white) (king|queen)) @@ -6903,37 +6911,37 @@ SUBPATTERNS the captured substrings are "white queen" and "queen", and are numbered 1 and 2. The maximum number of capturing subpatterns is 65535. - As a convenient shorthand, if any option settings are required at the - start of a non-capturing subpattern, the option letters may appear + As a convenient shorthand, if any option settings are required at the + start of a non-capturing subpattern, the option letters may appear between the "?" and the ":". Thus the two patterns (?i:saturday|sunday) (?:(?i)saturday|sunday) match exactly the same set of strings. Because alternative branches are - tried from left to right, and options are not reset until the end of - the subpattern is reached, an option setting in one branch does affect - subsequent branches, so the above patterns match "SUNDAY" as well as + tried from left to right, and options are not reset until the end of + the subpattern is reached, an option setting in one branch does affect + subsequent branches, so the above patterns match "SUNDAY" as well as "Saturday". DUPLICATE SUBPATTERN NUMBERS Perl 5.10 introduced a feature whereby each alternative in a subpattern - uses the same numbers for its capturing parentheses. Such a subpattern - starts with (?| and is itself a non-capturing subpattern. For example, + uses the same numbers for its capturing parentheses. Such a subpattern + starts with (?| and is itself a non-capturing subpattern. For example, consider this pattern: (?|(Sat)ur|(Sun))day - Because the two alternatives are inside a (?| group, both sets of cap- - turing parentheses are numbered one. Thus, when the pattern matches, - you can look at captured substring number one, whichever alternative - matched. This construct is useful when you want to capture part, but + Because the two alternatives are inside a (?| group, both sets of cap- + turing parentheses are numbered one. Thus, when the pattern matches, + you can look at captured substring number one, whichever alternative + matched. This construct is useful when you want to capture part, but not all, of one of a number of alternatives. Inside a (?| group, paren- - theses are numbered as usual, but the number is reset at the start of - each branch. The numbers of any capturing parentheses that follow the - subpattern start after the highest number used in any branch. The fol- + theses are numbered as usual, but the number is reset at the start of + each branch. The numbers of any capturing parentheses that follow the + subpattern start after the highest number used in any branch. The fol- lowing example is taken from the Perl documentation. The numbers under- neath show in which buffer the captured content will be stored. @@ -6941,14 +6949,14 @@ DUPLICATE SUBPATTERN NUMBERS / ( a ) (?| x ( y ) z | (p (q) r) | (t) u (v) ) ( z ) /x # 1 2 2 3 2 3 4 - A back reference to a numbered subpattern uses the most recent value - that is set for that number by any subpattern. The following pattern + A back reference to a numbered subpattern uses the most recent value + that is set for that number by any subpattern. The following pattern matches "abcabc" or "defdef": /(?|(abc)|(def))\1/ - In contrast, a subroutine call to a numbered subpattern always refers - to the first one in the pattern with the given number. The following + In contrast, a subroutine call to a numbered subpattern always refers + to the first one in the pattern with the given number. The following pattern matches "abcabc" or "defabc": /(?|(abc)|(def))(?1)/ @@ -6956,47 +6964,47 @@ DUPLICATE SUBPATTERN NUMBERS A relative reference such as (?-1) is no different: it is just a conve- nient way of computing an absolute group number. - If a condition test for a subpattern's having matched refers to a non- - unique number, the test is true if any of the subpatterns of that num- + If a condition test for a subpattern's having matched refers to a non- + unique number, the test is true if any of the subpatterns of that num- ber have matched. - An alternative approach to using this "branch reset" feature is to use + An alternative approach to using this "branch reset" feature is to use duplicate named subpatterns, as described in the next section. NAMED SUBPATTERNS - Identifying capturing parentheses by number is simple, but it can be - very hard to keep track of the numbers in complicated regular expres- - sions. Furthermore, if an expression is modified, the numbers may + Identifying capturing parentheses by number is simple, but it can be + very hard to keep track of the numbers in complicated regular expres- + sions. Furthermore, if an expression is modified, the numbers may change. To help with this difficulty, PCRE2 supports the naming of sub- patterns. This feature was not added to Perl until release 5.10. Python - had the feature earlier, and PCRE1 introduced it at release 4.0, using - the Python syntax. PCRE2 supports both the Perl and the Python syntax. - Perl allows identically numbered subpatterns to have different names, + had the feature earlier, and PCRE1 introduced it at release 4.0, using + the Python syntax. PCRE2 supports both the Perl and the Python syntax. + Perl allows identically numbered subpatterns to have different names, but PCRE2 does not. - In PCRE2, a subpattern can be named in one of three ways: (?<name>...) - or (?'name'...) as in Perl, or (?P<name>...) as in Python. References - to capturing parentheses from other parts of the pattern, such as back - references, recursion, and conditions, can be made by name as well as + In PCRE2, a subpattern can be named in one of three ways: (?<name>...) + or (?'name'...) as in Perl, or (?P<name>...) as in Python. References + to capturing parentheses from other parts of the pattern, such as back + references, recursion, and conditions, can be made by name as well as by number. - Names consist of up to 32 alphanumeric characters and underscores, but - must start with a non-digit. Named capturing parentheses are still - allocated numbers as well as names, exactly as if the names were not + Names consist of up to 32 alphanumeric characters and underscores, but + must start with a non-digit. Named capturing parentheses are still + allocated numbers as well as names, exactly as if the names were not present. The PCRE2 API provides function calls for extracting the name- - to-number translation table from a compiled pattern. There are also + to-number translation table from a compiled pattern. There are also convenience functions for extracting a captured substring by name. - By default, a name must be unique within a pattern, but it is possible - to relax this constraint by setting the PCRE2_DUPNAMES option at com- - pile time. (Duplicate names are also always permitted for subpatterns - with the same number, set up as described in the previous section.) - Duplicate names can be useful for patterns where only one instance of + By default, a name must be unique within a pattern, but it is possible + to relax this constraint by setting the PCRE2_DUPNAMES option at com- + pile time. (Duplicate names are also always permitted for subpatterns + with the same number, set up as described in the previous section.) + Duplicate names can be useful for patterns where only one instance of the named parentheses can match. Suppose you want to match the name of - a weekday, either as a 3-letter abbreviation or as the full name, and - in both cases you want to extract the abbreviation. This pattern + a weekday, either as a 3-letter abbreviation or as the full name, and + in both cases you want to extract the abbreviation. This pattern (ignoring the line breaks) does the job: (?<DN>Mon|Fri|Sun)(?:day)?| @@ -7005,18 +7013,18 @@ NAMED SUBPATTERNS (?<DN>Thu)(?:rsday)?| (?<DN>Sat)(?:urday)? - There are five capturing substrings, but only one is ever set after a + There are five capturing substrings, but only one is ever set after a match. (An alternative way of solving this problem is to use a "branch reset" subpattern, as described in the previous section.) - The convenience functions for extracting the data by name returns the - substring for the first (and in this example, the only) subpattern of - that name that matched. This saves searching to find which numbered + The convenience functions for extracting the data by name returns the + substring for the first (and in this example, the only) subpattern of + that name that matched. This saves searching to find which numbered subpattern it was. - If you make a back reference to a non-unique named subpattern from - elsewhere in the pattern, the subpatterns to which the name refers are - checked in the order in which they appear in the overall pattern. The + If you make a back reference to a non-unique named subpattern from + elsewhere in the pattern, the subpatterns to which the name refers are + checked in the order in which they appear in the overall pattern. The first one that is set is used for the reference. For example, this pat- tern matches both "foofoo" and "barbar" but not "foobar" or "barfoo": @@ -7024,29 +7032,29 @@ NAMED SUBPATTERNS If you make a subroutine call to a non-unique named subpattern, the one - that corresponds to the first occurrence of the name is used. In the + that corresponds to the first occurrence of the name is used. In the absence of duplicate numbers (see the previous section) this is the one with the lowest number. If you use a named reference in a condition test (see the section about conditions below), either to check whether a subpattern has matched, or - to check for recursion, all subpatterns with the same name are tested. - If the condition is true for any one of them, the overall condition is - true. This is the same behaviour as testing by number. For further - details of the interfaces for handling named subpatterns, see the + to check for recursion, all subpatterns with the same name are tested. + If the condition is true for any one of them, the overall condition is + true. This is the same behaviour as testing by number. For further + details of the interfaces for handling named subpatterns, see the pcre2api documentation. Warning: You cannot use different names to distinguish between two sub- - patterns with the same number because PCRE2 uses only the numbers when + patterns with the same number because PCRE2 uses only the numbers when matching. For this reason, an error is given at compile time if differ- - ent names are given to subpatterns with the same number. However, you + ent names are given to subpatterns with the same number. However, you can always give the same name to subpatterns with the same number, even when PCRE2_DUPNAMES is not set. REPETITION - Repetition is specified by quantifiers, which can follow any of the + Repetition is specified by quantifiers, which can follow any of the following items: a literal data character @@ -7060,17 +7068,17 @@ REPETITION a parenthesized subpattern (including most assertions) a subroutine call to a subpattern (recursive or otherwise) - The general repetition quantifier specifies a minimum and maximum num- - ber of permitted matches, by giving the two numbers in curly brackets - (braces), separated by a comma. The numbers must be less than 65536, + The general repetition quantifier specifies a minimum and maximum num- + ber of permitted matches, by giving the two numbers in curly brackets + (braces), separated by a comma. The numbers must be less than 65536, and the first must be less than or equal to the second. For example: z{2,4} - matches "zz", "zzz", or "zzzz". A closing brace on its own is not a - special character. If the second number is omitted, but the comma is - present, there is no upper limit; if the second number and the comma - are both omitted, the quantifier specifies an exact number of required + matches "zz", "zzz", or "zzzz". A closing brace on its own is not a + special character. If the second number is omitted, but the comma is + present, there is no upper limit; if the second number and the comma + are both omitted, the quantifier specifies an exact number of required matches. Thus [aeiou]{3,} @@ -7079,50 +7087,50 @@ REPETITION \d{8} - matches exactly 8 digits. An opening curly bracket that appears in a - position where a quantifier is not allowed, or one that does not match - the syntax of a quantifier, is taken as a literal character. For exam- + matches exactly 8 digits. An opening curly bracket that appears in a + position where a quantifier is not allowed, or one that does not match + the syntax of a quantifier, is taken as a literal character. For exam- ple, {,6} is not a quantifier, but a literal string of four characters. In UTF modes, quantifiers apply to characters rather than to individual - code units. Thus, for example, \x{100}{2} matches two characters, each + code units. Thus, for example, \x{100}{2} matches two characters, each of which is represented by a two-byte sequence in a UTF-8 string. Simi- - larly, \X{3} matches three Unicode extended grapheme clusters, each of - which may be several code units long (and they may be of different + larly, \X{3} matches three Unicode extended grapheme clusters, each of + which may be several code units long (and they may be of different lengths). The quantifier {0} is permitted, causing the expression to behave as if the previous item and the quantifier were not present. This may be use- - ful for subpatterns that are referenced as subroutines from elsewhere + ful for subpatterns that are referenced as subroutines from elsewhere in the pattern (but see also the section entitled "Defining subpatterns - for use by reference only" below). Items other than subpatterns that + for use by reference only" below). Items other than subpatterns that have a {0} quantifier are omitted from the compiled pattern. - For convenience, the three most common quantifiers have single-charac- + For convenience, the three most common quantifiers have single-charac- ter abbreviations: * is equivalent to {0,} + is equivalent to {1,} ? is equivalent to {0,1} - It is possible to construct infinite loops by following a subpattern + It is possible to construct infinite loops by following a subpattern that can match no characters with a quantifier that has no upper limit, for example: (a?)* - Earlier versions of Perl and PCRE1 used to give an error at compile + Earlier versions of Perl and PCRE1 used to give an error at compile time for such patterns. However, because there are cases where this can be useful, such patterns are now accepted, but if any repetition of the - subpattern does in fact match no characters, the loop is forcibly bro- + subpattern does in fact match no characters, the loop is forcibly bro- ken. - By default, the quantifiers are "greedy", that is, they match as much - as possible (up to the maximum number of permitted times), without - causing the rest of the pattern to fail. The classic example of where + By default, the quantifiers are "greedy", that is, they match as much + as possible (up to the maximum number of permitted times), without + causing the rest of the pattern to fail. The classic example of where this gives problems is in trying to match comments in C programs. These - appear between /* and */ and within the comment, individual * and / - characters may appear. An attempt to match C comments by applying the + appear between /* and */ and within the comment, individual * and / + characters may appear. An attempt to match C comments by applying the pattern /\*.*\*/ @@ -7131,19 +7139,19 @@ REPETITION /* first comment */ not comment /* second comment */ - fails, because it matches the entire string owing to the greediness of + fails, because it matches the entire string owing to the greediness of the .* item. If a quantifier is followed by a question mark, it ceases to be greedy, - and instead matches the minimum number of times possible, so the pat- + and instead matches the minimum number of times possible, so the pat- tern /\*.*?\*/ - does the right thing with the C comments. The meaning of the various - quantifiers is not otherwise changed, just the preferred number of - matches. Do not confuse this use of question mark with its use as a - quantifier in its own right. Because it has two uses, it can sometimes + does the right thing with the C comments. The meaning of the various + quantifiers is not otherwise changed, just the preferred number of + matches. Do not confuse this use of question mark with its use as a + quantifier in its own right. Because it has two uses, it can sometimes appear doubled, as in \d??\d @@ -7152,45 +7160,45 @@ REPETITION only way the rest of the pattern matches. If the PCRE2_UNGREEDY option is set (an option that is not available in - Perl), the quantifiers are not greedy by default, but individual ones - can be made greedy by following them with a question mark. In other + Perl), the quantifiers are not greedy by default, but individual ones + can be made greedy by following them with a question mark. In other words, it inverts the default behaviour. - When a parenthesized subpattern is quantified with a minimum repeat - count that is greater than 1 or with a limited maximum, more memory is - required for the compiled pattern, in proportion to the size of the + When a parenthesized subpattern is quantified with a minimum repeat + count that is greater than 1 or with a limited maximum, more memory is + required for the compiled pattern, in proportion to the size of the minimum or maximum. - If a pattern starts with .* or .{0,} and the PCRE2_DOTALL option - (equivalent to Perl's /s) is set, thus allowing the dot to match new- - lines, the pattern is implicitly anchored, because whatever follows - will be tried against every character position in the subject string, - so there is no point in retrying the overall match at any position + If a pattern starts with .* or .{0,} and the PCRE2_DOTALL option + (equivalent to Perl's /s) is set, thus allowing the dot to match new- + lines, the pattern is implicitly anchored, because whatever follows + will be tried against every character position in the subject string, + so there is no point in retrying the overall match at any position after the first. PCRE2 normally treats such a pattern as though it were preceded by \A. - In cases where it is known that the subject string contains no new- - lines, it is worth setting PCRE2_DOTALL in order to obtain this opti- + In cases where it is known that the subject string contains no new- + lines, it is worth setting PCRE2_DOTALL in order to obtain this opti- mization, or alternatively, using ^ to indicate anchoring explicitly. - However, there are some cases where the optimization cannot be used. + However, there are some cases where the optimization cannot be used. When .* is inside capturing parentheses that are the subject of a back reference elsewhere in the pattern, a match at the start may fail where a later one succeeds. Consider, for example: (.*)abc\1 - If the subject is "xyz123abc123" the match point is the fourth charac- + If the subject is "xyz123abc123" the match point is the fourth charac- ter. For this reason, such a pattern is not implicitly anchored. - Another case where implicit anchoring is not applied is when the lead- - ing .* is inside an atomic group. Once again, a match at the start may + Another case where implicit anchoring is not applied is when the lead- + ing .* is inside an atomic group. Once again, a match at the start may fail where a later one succeeds. Consider this pattern: (?>.*?a)b - It matches "ab" in the subject "aab". The use of the backtracking con- - trol verbs (*PRUNE) and (*SKIP) also disable this optimization, and + It matches "ab" in the subject "aab". The use of the backtracking con- + trol verbs (*PRUNE) and (*SKIP) also disable this optimization, and there is an option, PCRE2_NO_DOTSTAR_ANCHOR, to do so explicitly. When a capturing subpattern is repeated, the value captured is the sub- @@ -7199,8 +7207,8 @@ REPETITION (tweedle[dume]{3}\s*)+ has matched "tweedledum tweedledee" the value of the captured substring - is "tweedledee". However, if there are nested capturing subpatterns, - the corresponding captured values may have been set in previous itera- + is "tweedledee". However, if there are nested capturing subpatterns, + the corresponding captured values may have been set in previous itera- tions. For example, after (a|(b))+ @@ -7210,53 +7218,53 @@ REPETITION ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS - With both maximizing ("greedy") and minimizing ("ungreedy" or "lazy") - repetition, failure of what follows normally causes the repeated item - to be re-evaluated to see if a different number of repeats allows the - rest of the pattern to match. Sometimes it is useful to prevent this, - either to change the nature of the match, or to cause it fail earlier - than it otherwise might, when the author of the pattern knows there is + With both maximizing ("greedy") and minimizing ("ungreedy" or "lazy") + repetition, failure of what follows normally causes the repeated item + to be re-evaluated to see if a different number of repeats allows the + rest of the pattern to match. Sometimes it is useful to prevent this, + either to change the nature of the match, or to cause it fail earlier + than it otherwise might, when the author of the pattern knows there is no point in carrying on. - Consider, for example, the pattern \d+foo when applied to the subject + Consider, for example, the pattern \d+foo when applied to the subject line 123456bar After matching all 6 digits and then failing to match "foo", the normal - action of the matcher is to try again with only 5 digits matching the - \d+ item, and then with 4, and so on, before ultimately failing. - "Atomic grouping" (a term taken from Jeffrey Friedl's book) provides - the means for specifying that once a subpattern has matched, it is not + action of the matcher is to try again with only 5 digits matching the + \d+ item, and then with 4, and so on, before ultimately failing. + "Atomic grouping" (a term taken from Jeffrey Friedl's book) provides + the means for specifying that once a subpattern has matched, it is not to be re-evaluated in this way. - If we use atomic grouping for the previous example, the matcher gives - up immediately on failing to match "foo" the first time. The notation + If we use atomic grouping for the previous example, the matcher gives + up immediately on failing to match "foo" the first time. The notation is a kind of special parenthesis, starting with (?> as in this example: (?>\d+)foo - This kind of parenthesis "locks up" the part of the pattern it con- - tains once it has matched, and a failure further into the pattern is - prevented from backtracking into it. Backtracking past it to previous + This kind of parenthesis "locks up" the part of the pattern it con- + tains once it has matched, and a failure further into the pattern is + prevented from backtracking into it. Backtracking past it to previous items, however, works as normal. - An alternative description is that a subpattern of this type matches - exactly the string of characters that an identical standalone pattern + An alternative description is that a subpattern of this type matches + exactly the string of characters that an identical standalone pattern would match, if anchored at the current point in the subject string. Atomic grouping subpatterns are not capturing subpatterns. Simple cases such as the above example can be thought of as a maximizing repeat that - must swallow everything it can. So, while both \d+ and \d+? are pre- - pared to adjust the number of digits they match in order to make the + must swallow everything it can. So, while both \d+ and \d+? are pre- + pared to adjust the number of digits they match in order to make the rest of the pattern match, (?>\d+) can only match an entire sequence of digits. - Atomic groups in general can of course contain arbitrarily complicated - subpatterns, and can be nested. However, when the subpattern for an + Atomic groups in general can of course contain arbitrarily complicated + subpatterns, and can be nested. However, when the subpattern for an atomic group is just a single repeated item, as in the example above, a - simpler notation, called a "possessive quantifier" can be used. This - consists of an additional + character following a quantifier. Using + simpler notation, called a "possessive quantifier" can be used. This + consists of an additional + character following a quantifier. Using this notation, the previous example can be rewritten as \d++foo @@ -7266,46 +7274,46 @@ ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS (abc|xyz){2,3}+ - Possessive quantifiers are always greedy; the setting of the - PCRE2_UNGREEDY option is ignored. They are a convenient notation for - the simpler forms of atomic group. However, there is no difference in + Possessive quantifiers are always greedy; the setting of the + PCRE2_UNGREEDY option is ignored. They are a convenient notation for + the simpler forms of atomic group. However, there is no difference in the meaning of a possessive quantifier and the equivalent atomic group, - though there may be a performance difference; possessive quantifiers + though there may be a performance difference; possessive quantifiers should be slightly faster. - The possessive quantifier syntax is an extension to the Perl 5.8 syn- - tax. Jeffrey Friedl originated the idea (and the name) in the first + The possessive quantifier syntax is an extension to the Perl 5.8 syn- + tax. Jeffrey Friedl originated the idea (and the name) in the first edition of his book. Mike McCloskey liked it, so implemented it when he built Sun's Java package, and PCRE1 copied it from there. It ultimately found its way into Perl at release 5.10. - PCRE2 has an optimization that automatically "possessifies" certain - simple pattern constructs. For example, the sequence A+B is treated as - A++B because there is no point in backtracking into a sequence of A's + PCRE2 has an optimization that automatically "possessifies" certain + simple pattern constructs. For example, the sequence A+B is treated as + A++B because there is no point in backtracking into a sequence of A's when B must follow. This feature can be disabled by the PCRE2_NO_AUTO- POSSESS option, or starting the pattern with (*NO_AUTO_POSSESS). - When a pattern contains an unlimited repeat inside a subpattern that - can itself be repeated an unlimited number of times, the use of an - atomic group is the only way to avoid some failing matches taking a + When a pattern contains an unlimited repeat inside a subpattern that + can itself be repeated an unlimited number of times, the use of an + atomic group is the only way to avoid some failing matches taking a very long time indeed. The pattern (\D+|<\d+>)*[!?] - matches an unlimited number of substrings that either consist of non- - digits, or digits enclosed in <>, followed by either ! or ?. When it + matches an unlimited number of substrings that either consist of non- + digits, or digits enclosed in <>, followed by either ! or ?. When it matches, it runs quickly. However, if it is applied to aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa - it takes a long time before reporting failure. This is because the - string can be divided between the internal \D+ repeat and the external - * repeat in a large number of ways, and all have to be tried. (The - example uses [!?] rather than a single character at the end, because - both PCRE2 and Perl have an optimization that allows for fast failure - when a single character is used. They remember the last single charac- - ter that is required for a match, and fail early if it is not present - in the string.) If the pattern is changed so that it uses an atomic + it takes a long time before reporting failure. This is because the + string can be divided between the internal \D+ repeat and the external + * repeat in a large number of ways, and all have to be tried. (The + example uses [!?] rather than a single character at the end, because + both PCRE2 and Perl have an optimization that allows for fast failure + when a single character is used. They remember the last single charac- + ter that is required for a match, and fail early if it is not present + in the string.) If the pattern is changed so that it uses an atomic group, like this: ((?>\D+)|<\d+>)*[!?] @@ -7317,28 +7325,28 @@ BACK REFERENCES Outside a character class, a backslash followed by a digit greater than 0 (and possibly further digits) is a back reference to a capturing sub- - pattern earlier (that is, to its left) in the pattern, provided there + pattern earlier (that is, to its left) in the pattern, provided there have been that many previous capturing left parentheses. - However, if the decimal number following the backslash is less than 8, - it is always taken as a back reference, and causes an error only if - there are not that many capturing left parentheses in the entire pat- - tern. In other words, the parentheses that are referenced need not be - to the left of the reference for numbers less than 8. A "forward back - reference" of this type can make sense when a repetition is involved - and the subpattern to the right has participated in an earlier itera- + However, if the decimal number following the backslash is less than 8, + it is always taken as a back reference, and causes an error only if + there are not that many capturing left parentheses in the entire pat- + tern. In other words, the parentheses that are referenced need not be + to the left of the reference for numbers less than 8. A "forward back + reference" of this type can make sense when a repetition is involved + and the subpattern to the right has participated in an earlier itera- tion. - It is not possible to have a numerical "forward back reference" to a - subpattern whose number is 8 or more using this syntax because a - sequence such as \50 is interpreted as a character defined in octal. + It is not possible to have a numerical "forward back reference" to a + subpattern whose number is 8 or more using this syntax because a + sequence such as \50 is interpreted as a character defined in octal. See the subsection entitled "Non-printing characters" above for further - details of the handling of digits following a backslash. There is no - such problem when named parentheses are used. A back reference to any + details of the handling of digits following a backslash. There is no + such problem when named parentheses are used. A back reference to any subpattern is possible using named parentheses (see below). - Another way of avoiding the ambiguity inherent in the use of digits - following a backslash is to use the \g escape sequence. This escape + Another way of avoiding the ambiguity inherent in the use of digits + following a backslash is to use the \g escape sequence. This escape must be followed by a signed or unsigned number, optionally enclosed in braces. These examples are all identical: @@ -7346,46 +7354,46 @@ BACK REFERENCES (ring), \g1 (ring), \g{1} - An unsigned number specifies an absolute reference without the ambigu- + An unsigned number specifies an absolute reference without the ambigu- ity that is present in the older syntax. It is also useful when literal - digits follow the reference. A signed number is a relative reference. + digits follow the reference. A signed number is a relative reference. Consider this example: (abc(def)ghi)\g{-1} The sequence \g{-1} is a reference to the most recently started captur- ing subpattern before \g, that is, is it equivalent to \2 in this exam- - ple. Similarly, \g{-2} would be equivalent to \1. The use of relative - references can be helpful in long patterns, and also in patterns that - are created by joining together fragments that contain references + ple. Similarly, \g{-2} would be equivalent to \1. The use of relative + references can be helpful in long patterns, and also in patterns that + are created by joining together fragments that contain references within themselves. - The sequence \g{+1} is a reference to the next capturing subpattern. - This kind of forward reference can be useful it patterns that repeat. + The sequence \g{+1} is a reference to the next capturing subpattern. + This kind of forward reference can be useful it patterns that repeat. Perl does not support the use of + in this way. - A back reference matches whatever actually matched the capturing sub- - pattern in the current subject string, rather than anything matching + A back reference matches whatever actually matched the capturing sub- + pattern in the current subject string, rather than anything matching the subpattern itself (see "Subpatterns as subroutines" below for a way of doing that). So the pattern (sens|respons)e and \1ibility - matches "sense and sensibility" and "response and responsibility", but - not "sense and responsibility". If caseful matching is in force at the - time of the back reference, the case of letters is relevant. For exam- + matches "sense and sensibility" and "response and responsibility", but + not "sense and responsibility". If caseful matching is in force at the + time of the back reference, the case of letters is relevant. For exam- ple, ((?i)rah)\s+\1 - matches "rah rah" and "RAH RAH", but not "RAH rah", even though the + matches "rah rah" and "RAH RAH", but not "RAH rah", even though the original capturing subpattern is matched caselessly. - There are several different ways of writing back references to named - subpatterns. The .NET syntax \k{name} and the Perl syntax \k<name> or - \k'name' are supported, as is the Python syntax (?P=name). Perl 5.10's + There are several different ways of writing back references to named + subpatterns. The .NET syntax \k{name} and the Perl syntax \k<name> or + \k'name' are supported, as is the Python syntax (?P=name). Perl 5.10's unified back reference syntax, in which \g can be used for both numeric - and named references, is also supported. We could rewrite the above + and named references, is also supported. We could rewrite the above example in any of the following ways: (?<p1>(?i)rah)\s+\k<p1> @@ -7393,96 +7401,96 @@ BACK REFERENCES (?P<p1>(?i)rah)\s+(?P=p1) (?<p1>(?i)rah)\s+\g{p1} - A subpattern that is referenced by name may appear in the pattern + A subpattern that is referenced by name may appear in the pattern before or after the reference. - There may be more than one back reference to the same subpattern. If a - subpattern has not actually been used in a particular match, any back + There may be more than one back reference to the same subpattern. If a + subpattern has not actually been used in a particular match, any back references to it always fail by default. For example, the pattern (a|(bc))\2 - always fails if it starts to match "a" rather than "bc". However, if - the PCRE2_MATCH_UNSET_BACKREF option is set at compile time, a back + always fails if it starts to match "a" rather than "bc". However, if + the PCRE2_MATCH_UNSET_BACKREF option is set at compile time, a back reference to an unset value matches an empty string. - Because there may be many capturing parentheses in a pattern, all dig- - its following a backslash are taken as part of a potential back refer- - ence number. If the pattern continues with a digit character, some - delimiter must be used to terminate the back reference. If the - PCRE2_EXTENDED option is set, this can be white space. Otherwise, the + Because there may be many capturing parentheses in a pattern, all dig- + its following a backslash are taken as part of a potential back refer- + ence number. If the pattern continues with a digit character, some + delimiter must be used to terminate the back reference. If the + PCRE2_EXTENDED option is set, this can be white space. Otherwise, the \g{ syntax or an empty comment (see "Comments" below) can be used. Recursive back references - A back reference that occurs inside the parentheses to which it refers - fails when the subpattern is first used, so, for example, (a\1) never - matches. However, such references can be useful inside repeated sub- + A back reference that occurs inside the parentheses to which it refers + fails when the subpattern is first used, so, for example, (a\1) never + matches. However, such references can be useful inside repeated sub- patterns. For example, the pattern (a|b\1)+ matches any number of "a"s and also "aba", "ababbaa" etc. At each iter- - ation of the subpattern, the back reference matches the character - string corresponding to the previous iteration. In order for this to - work, the pattern must be such that the first iteration does not need - to match the back reference. This can be done using alternation, as in + ation of the subpattern, the back reference matches the character + string corresponding to the previous iteration. In order for this to + work, the pattern must be such that the first iteration does not need + to match the back reference. This can be done using alternation, as in the example above, or by a quantifier with a minimum of zero. - Back references of this type cause the group that they reference to be - treated as an atomic group. Once the whole group has been matched, a - subsequent matching failure cannot cause backtracking into the middle + Back references of this type cause the group that they reference to be + treated as an atomic group. Once the whole group has been matched, a + subsequent matching failure cannot cause backtracking into the middle of the group. ASSERTIONS - An assertion is a test on the characters following or preceding the + An assertion is a test on the characters following or preceding the current matching point that does not consume any characters. The simple - assertions coded as \b, \B, \A, \G, \Z, \z, ^ and $ are described + assertions coded as \b, \B, \A, \G, \Z, \z, ^ and $ are described above. - More complicated assertions are coded as subpatterns. There are two - kinds: those that look ahead of the current position in the subject - string, and those that look behind it, and in each case an assertion - may be positive (must succeed for matching to continue) or negative + More complicated assertions are coded as subpatterns. There are two + kinds: those that look ahead of the current position in the subject + string, and those that look behind it, and in each case an assertion + may be positive (must succeed for matching to continue) or negative (must not succeed for matching to continue). An assertion subpattern is - matched in the normal way, except that, when matching continues after- - wards, the matching position in the subject string is as it was at the + matched in the normal way, except that, when matching continues after- + wards, the matching position in the subject string is as it was at the start of the assertion. - Assertion subpatterns are not capturing subpatterns. If an assertion - contains capturing subpatterns within it, these are counted for the - purposes of numbering the capturing subpatterns in the whole pattern. - However, substring capturing is carried out only for positive asser- + Assertion subpatterns are not capturing subpatterns. If an assertion + contains capturing subpatterns within it, these are counted for the + purposes of numbering the capturing subpatterns in the whole pattern. + However, substring capturing is carried out only for positive asser- tions that succeed, that is, one of their branches matches, so matching - continues after the assertion. If all branches of a positive assertion + continues after the assertion. If all branches of a positive assertion fail to match, nothing is captured, and control is passed to the previ- ous backtracking point. - No capturing is done for a negative assertion unless it is being used - as a condition in a conditional subpattern (see the discussion below). - Matching continues after a non-conditional negative assertion only if + No capturing is done for a negative assertion unless it is being used + as a condition in a conditional subpattern (see the discussion below). + Matching continues after a non-conditional negative assertion only if all its branches fail to match. - For compatibility with Perl, most assertion subpatterns may be - repeated; though it makes no sense to assert the same thing several - times, the side effect of capturing parentheses may occasionally be - useful. However, an assertion that forms the condition for a condi- - tional subpattern may not be quantified. In practice, for other asser- + For compatibility with Perl, most assertion subpatterns may be + repeated; though it makes no sense to assert the same thing several + times, the side effect of capturing parentheses may occasionally be + useful. However, an assertion that forms the condition for a condi- + tional subpattern may not be quantified. In practice, for other asser- tions, there only three cases: - (1) If the quantifier is {0}, the assertion is never obeyed during - matching. However, it may contain internal capturing parenthesized + (1) If the quantifier is {0}, the assertion is never obeyed during + matching. However, it may contain internal capturing parenthesized groups that are called from elsewhere via the subroutine mechanism. - (2) If quantifier is {0,n} where n is greater than zero, it is treated - as if it were {0,1}. At run time, the rest of the pattern match is + (2) If quantifier is {0,n} where n is greater than zero, it is treated + as if it were {0,1}. At run time, the rest of the pattern match is tried with and without the assertion, the order depending on the greed- iness of the quantifier. - (3) If the minimum repetition is greater than zero, the quantifier is - ignored. The assertion is obeyed just once when encountered during + (3) If the minimum repetition is greater than zero, the quantifier is + ignored. The assertion is obeyed just once when encountered during matching. Lookahead assertions @@ -7492,38 +7500,38 @@ ASSERTIONS \w+(?=;) - matches a word followed by a semicolon, but does not include the semi- + matches a word followed by a semicolon, but does not include the semi- colon in the match, and foo(?!bar) - matches any occurrence of "foo" that is not followed by "bar". Note + matches any occurrence of "foo" that is not followed by "bar". Note that the apparently similar pattern (?!foo)bar - does not find an occurrence of "bar" that is preceded by something - other than "foo"; it finds any occurrence of "bar" whatsoever, because + does not find an occurrence of "bar" that is preceded by something + other than "foo"; it finds any occurrence of "bar" whatsoever, because the assertion (?!foo) is always true when the next three characters are "bar". A lookbehind assertion is needed to achieve the other effect. If you want to force a matching failure at some point in a pattern, the - most convenient way to do it is with (?!) because an empty string - always matches, so an assertion that requires there not to be an empty + most convenient way to do it is with (?!) because an empty string + always matches, so an assertion that requires there not to be an empty string must always fail. The backtracking control verb (*FAIL) or (*F) is a synonym for (?!). Lookbehind assertions - Lookbehind assertions start with (?<= for positive assertions and (?<! + Lookbehind assertions start with (?<= for positive assertions and (?<! for negative assertions. For example, (?<!foo)bar - does find an occurrence of "bar" that is not preceded by "foo". The - contents of a lookbehind assertion are restricted such that all the + does find an occurrence of "bar" that is not preceded by "foo". The + contents of a lookbehind assertion are restricted such that all the strings it matches must have a fixed length. However, if there are sev- - eral top-level alternatives, they do not all have to have the same + eral top-level alternatives, they do not all have to have the same fixed length. Thus (?<=bullock|donkey) @@ -7532,74 +7540,74 @@ ASSERTIONS (?<!dogs?|cats?) - causes an error at compile time. Branches that match different length - strings are permitted only at the top level of a lookbehind assertion. + causes an error at compile time. Branches that match different length + strings are permitted only at the top level of a lookbehind assertion. This is an extension compared with Perl, which requires all branches to match the same length of string. An assertion such as (?<=ab(c|de)) - is not permitted, because its single top-level branch can match two - different lengths, but it is acceptable to PCRE2 if rewritten to use + is not permitted, because its single top-level branch can match two + different lengths, but it is acceptable to PCRE2 if rewritten to use two top-level branches: (?<=abc|abde) - In some cases, the escape sequence \K (see above) can be used instead + In some cases, the escape sequence \K (see above) can be used instead of a lookbehind assertion to get round the fixed-length restriction. - The implementation of lookbehind assertions is, for each alternative, - to temporarily move the current position back by the fixed length and + The implementation of lookbehind assertions is, for each alternative, + to temporarily move the current position back by the fixed length and then try to match. If there are insufficient characters before the cur- rent position, the assertion fails. - In UTF-8 and UTF-16 modes, PCRE2 does not allow the \C escape (which - matches a single code unit even in a UTF mode) to appear in lookbehind - assertions, because it makes it impossible to calculate the length of - the lookbehind. The \X and \R escapes, which can match different num- + In UTF-8 and UTF-16 modes, PCRE2 does not allow the \C escape (which + matches a single code unit even in a UTF mode) to appear in lookbehind + assertions, because it makes it impossible to calculate the length of + the lookbehind. The \X and \R escapes, which can match different num- bers of code units, are never permitted in lookbehinds. - "Subroutine" calls (see below) such as (?2) or (?&X) are permitted in - lookbehinds, as long as the subpattern matches a fixed-length string. - However, recursion, that is, a "subroutine" call into a group that is + "Subroutine" calls (see below) such as (?2) or (?&X) are permitted in + lookbehinds, as long as the subpattern matches a fixed-length string. + However, recursion, that is, a "subroutine" call into a group that is already active, is not supported. - Perl does not support back references in lookbehinds. PCRE2 does sup- - port them, but only if certain conditions are met. The - PCRE2_MATCH_UNSET_BACKREF option must not be set, there must be no use + Perl does not support back references in lookbehinds. PCRE2 does sup- + port them, but only if certain conditions are met. The + PCRE2_MATCH_UNSET_BACKREF option must not be set, there must be no use of (?| in the pattern (it creates duplicate subpattern numbers), and if - the back reference is by name, the name must be unique. Of course, the - referenced subpattern must itself be of fixed length. The following + the back reference is by name, the name must be unique. Of course, the + referenced subpattern must itself be of fixed length. The following pattern matches words containing at least two characters that begin and end with the same character: \b(\w)\w++(?<=\1) - Possessive quantifiers can be used in conjunction with lookbehind + Possessive quantifiers can be used in conjunction with lookbehind assertions to specify efficient matching of fixed-length strings at the end of subject strings. Consider a simple pattern such as abcd$ - when applied to a long string that does not match. Because matching - proceeds from left to right, PCRE2 will look for each "a" in the sub- - ject and then see if what follows matches the rest of the pattern. If + when applied to a long string that does not match. Because matching + proceeds from left to right, PCRE2 will look for each "a" in the sub- + ject and then see if what follows matches the rest of the pattern. If the pattern is specified as ^.*abcd$ - the initial .* matches the entire string at first, but when this fails + the initial .* matches the entire string at first, but when this fails (because there is no following "a"), it backtracks to match all but the - last character, then all but the last two characters, and so on. Once - again the search for "a" covers the entire string, from right to left, + last character, then all but the last two characters, and so on. Once + again the search for "a" covers the entire string, from right to left, so we are no better off. However, if the pattern is written as ^.*+(?<=abcd) there can be no backtracking for the .*+ item because of the possessive quantifier; it can match only the entire string. The subsequent lookbe- - hind assertion does a single test on the last four characters. If it - fails, the match fails immediately. For long strings, this approach + hind assertion does a single test on the last four characters. If it + fails, the match fails immediately. For long strings, this approach makes a significant difference to the processing time. Using multiple assertions @@ -7608,18 +7616,18 @@ ASSERTIONS (?<=\d{3})(?<!999)foo - matches "foo" preceded by three digits that are not "999". Notice that - each of the assertions is applied independently at the same point in - the subject string. First there is a check that the previous three - characters are all digits, and then there is a check that the same + matches "foo" preceded by three digits that are not "999". Notice that + each of the assertions is applied independently at the same point in + the subject string. First there is a check that the previous three + characters are all digits, and then there is a check that the same three characters are not "999". This pattern does not match "foo" pre- - ceded by six characters, the first of which are digits and the last - three of which are not "999". For example, it doesn't match "123abc- + ceded by six characters, the first of which are digits and the last + three of which are not "999". For example, it doesn't match "123abc- foo". A pattern to do that is (?<=\d{3}...)(?<!999)foo - This time the first assertion looks at the preceding six characters, + This time the first assertion looks at the preceding six characters, checking that the first three are digits, and then the second assertion checks that the preceding three characters are not "999". @@ -7627,29 +7635,29 @@ ASSERTIONS (?<=(?<!foo)bar)baz - matches an occurrence of "baz" that is preceded by "bar" which in turn + matches an occurrence of "baz" that is preceded by "bar" which in turn is not preceded by "foo", while (?<=\d{3}(?!999)...)foo - is another pattern that matches "foo" preceded by three digits and any + is another pattern that matches "foo" preceded by three digits and any three characters that are not "999". CONDITIONAL SUBPATTERNS - It is possible to cause the matching process to obey a subpattern con- - ditionally or to choose between two alternative subpatterns, depending - on the result of an assertion, or whether a specific capturing subpat- - tern has already been matched. The two possible forms of conditional + It is possible to cause the matching process to obey a subpattern con- + ditionally or to choose between two alternative subpatterns, depending + on the result of an assertion, or whether a specific capturing subpat- + tern has already been matched. The two possible forms of conditional subpattern are: (?(condition)yes-pattern) (?(condition)yes-pattern|no-pattern) - If the condition is satisfied, the yes-pattern is used; otherwise the - no-pattern (if present) is used. If there are more than two alterna- - tives in the subpattern, a compile-time error occurs. Each of the two + If the condition is satisfied, the yes-pattern is used; otherwise the + no-pattern (if present) is used. If there are more than two alterna- + tives in the subpattern, a compile-time error occurs. Each of the two alternatives may itself contain nested subpatterns of any form, includ- ing conditional subpatterns; the restriction to two alternatives applies only at the level of the condition. This pattern fragment is an @@ -7658,88 +7666,88 @@ CONDITIONAL SUBPATTERNS (?(1) (A|B|C) | (D | (?(2)E|F) | E) ) - There are five kinds of condition: references to subpatterns, refer- - ences to recursion, two pseudo-conditions called DEFINE and VERSION, + There are five kinds of condition: references to subpatterns, refer- + ences to recursion, two pseudo-conditions called DEFINE and VERSION, and assertions. Checking for a used subpattern by number - If the text between the parentheses consists of a sequence of digits, + If the text between the parentheses consists of a sequence of digits, the condition is true if a capturing subpattern of that number has pre- - viously matched. If there is more than one capturing subpattern with - the same number (see the earlier section about duplicate subpattern - numbers), the condition is true if any of them have matched. An alter- - native notation is to precede the digits with a plus or minus sign. In - this case, the subpattern number is relative rather than absolute. The - most recently opened parentheses can be referenced by (?(-1), the next - most recent by (?(-2), and so on. Inside loops it can also make sense + viously matched. If there is more than one capturing subpattern with + the same number (see the earlier section about duplicate subpattern + numbers), the condition is true if any of them have matched. An alter- + native notation is to precede the digits with a plus or minus sign. In + this case, the subpattern number is relative rather than absolute. The + most recently opened parentheses can be referenced by (?(-1), the next + most recent by (?(-2), and so on. Inside loops it can also make sense to refer to subsequent groups. The next parentheses to be opened can be - referenced as (?(+1), and so on. (The value zero in any of these forms + referenced as (?(+1), and so on. (The value zero in any of these forms is not used; it provokes a compile-time error.) - Consider the following pattern, which contains non-significant white - space to make it more readable (assume the PCRE2_EXTENDED option) and + Consider the following pattern, which contains non-significant white + space to make it more readable (assume the PCRE2_EXTENDED option) and to divide it into three parts for ease of discussion: ( \( )? [^()]+ (?(1) \) ) - The first part matches an optional opening parenthesis, and if that + The first part matches an optional opening parenthesis, and if that character is present, sets it as the first captured substring. The sec- - ond part matches one or more characters that are not parentheses. The - third part is a conditional subpattern that tests whether or not the - first set of parentheses matched. If they did, that is, if subject - started with an opening parenthesis, the condition is true, and so the - yes-pattern is executed and a closing parenthesis is required. Other- - wise, since no-pattern is not present, the subpattern matches nothing. - In other words, this pattern matches a sequence of non-parentheses, + ond part matches one or more characters that are not parentheses. The + third part is a conditional subpattern that tests whether or not the + first set of parentheses matched. If they did, that is, if subject + started with an opening parenthesis, the condition is true, and so the + yes-pattern is executed and a closing parenthesis is required. Other- + wise, since no-pattern is not present, the subpattern matches nothing. + In other words, this pattern matches a sequence of non-parentheses, optionally enclosed in parentheses. - If you were embedding this pattern in a larger one, you could use a + If you were embedding this pattern in a larger one, you could use a relative reference: ...other stuff... ( \( )? [^()]+ (?(-1) \) ) ... - This makes the fragment independent of the parentheses in the larger + This makes the fragment independent of the parentheses in the larger pattern. Checking for a used subpattern by name - Perl uses the syntax (?(<name>)...) or (?('name')...) to test for a - used subpattern by name. For compatibility with earlier versions of - PCRE1, which had this facility before Perl, the syntax (?(name)...) is - also recognized. Note, however, that undelimited names consisting of - the letter R followed by digits are ambiguous (see the following sec- + Perl uses the syntax (?(<name>)...) or (?('name')...) to test for a + used subpattern by name. For compatibility with earlier versions of + PCRE1, which had this facility before Perl, the syntax (?(name)...) is + also recognized. Note, however, that undelimited names consisting of + the letter R followed by digits are ambiguous (see the following sec- tion). Rewriting the above example to use a named subpattern gives this: (?<OPEN> \( )? [^()]+ (?(<OPEN>) \) ) - If the name used in a condition of this kind is a duplicate, the test - is applied to all subpatterns of the same name, and is true if any one + If the name used in a condition of this kind is a duplicate, the test + is applied to all subpatterns of the same name, and is true if any one of them has matched. Checking for pattern recursion - "Recursion" in this sense refers to any subroutine-like call from one - part of the pattern to another, whether or not it is actually recur- - sive. See the sections entitled "Recursive patterns" and "Subpatterns + "Recursion" in this sense refers to any subroutine-like call from one + part of the pattern to another, whether or not it is actually recur- + sive. See the sections entitled "Recursive patterns" and "Subpatterns as subroutines" below for details of recursion and subpattern calls. - If a condition is the string (R), and there is no subpattern with the - name R, the condition is true if matching is currently in a recursion - or subroutine call to the whole pattern or any subpattern. If digits - follow the letter R, and there is no subpattern with that name, the + If a condition is the string (R), and there is no subpattern with the + name R, the condition is true if matching is currently in a recursion + or subroutine call to the whole pattern or any subpattern. If digits + follow the letter R, and there is no subpattern with that name, the condition is true if the most recent call is into a subpattern with the - given number, which must exist somewhere in the overall pattern. This + given number, which must exist somewhere in the overall pattern. This is a contrived example that is equivalent to a+b: ((?(R1)a+|(?1)b)) - However, in both cases, if there is a subpattern with a matching name, - the condition tests for its being set, as described in the section - above, instead of testing for recursion. For example, creating a group - with the name R1 by adding (?<R1>) to the above pattern completely + However, in both cases, if there is a subpattern with a matching name, + the condition tests for its being set, as described in the section + above, instead of testing for recursion. For example, creating a group + with the name R1 by adding (?<R1>) to the above pattern completely changes its meaning. If a name preceded by ampersand follows the letter R, for example: @@ -7750,7 +7758,7 @@ CONDITIONAL SUBPATTERNS of that name (which must exist within the pattern). This condition does not check the entire recursion stack. It tests only - the current level. If the name used in a condition of this kind is a + the current level. If the name used in a condition of this kind is a duplicate, the test is applied to all subpatterns of the same name, and is true if any one of them is the most recent recursion. @@ -7759,10 +7767,10 @@ CONDITIONAL SUBPATTERNS Defining subpatterns for use by reference only If the condition is the string (DEFINE), the condition is always false, - even if there is a group with the name DEFINE. In this case, there may + even if there is a group with the name DEFINE. In this case, there may be only one alternative in the subpattern. It is always skipped if con- - trol reaches this point in the pattern; the idea of DEFINE is that it - can be used to define subroutines that can be referenced from else- + trol reaches this point in the pattern; the idea of DEFINE is that it + can be used to define subroutines that can be referenced from else- where. (The use of subroutines is described below.) For example, a pat- tern to match an IPv4 address such as "192.168.23.245" could be written like this (ignore white space and line breaks): @@ -7770,97 +7778,97 @@ CONDITIONAL SUBPATTERNS (?(DEFINE) (?<byte> 2[0-4]\d | 25[0-5] | 1\d\d | [1-9]?\d) ) \b (?&byte) (\.(?&byte)){3} \b - The first part of the pattern is a DEFINE group inside which a another - group named "byte" is defined. This matches an individual component of - an IPv4 address (a number less than 256). When matching takes place, - this part of the pattern is skipped because DEFINE acts like a false - condition. The rest of the pattern uses references to the named group - to match the four dot-separated components of an IPv4 address, insist- + The first part of the pattern is a DEFINE group inside which a another + group named "byte" is defined. This matches an individual component of + an IPv4 address (a number less than 256). When matching takes place, + this part of the pattern is skipped because DEFINE acts like a false + condition. The rest of the pattern uses references to the named group + to match the four dot-separated components of an IPv4 address, insist- ing on a word boundary at each end. Checking the PCRE2 version - Programs that link with a PCRE2 library can check the version by call- - ing pcre2_config() with appropriate arguments. Users of applications - that do not have access to the underlying code cannot do this. A spe- - cial "condition" called VERSION exists to allow such users to discover + Programs that link with a PCRE2 library can check the version by call- + ing pcre2_config() with appropriate arguments. Users of applications + that do not have access to the underlying code cannot do this. A spe- + cial "condition" called VERSION exists to allow such users to discover which version of PCRE2 they are dealing with by using this condition to - match a string such as "yesno". VERSION must be followed either by "=" + match a string such as "yesno". VERSION must be followed either by "=" or ">=" and a version number. For example: (?(VERSION>=10.4)yes|no) - This pattern matches "yes" if the PCRE2 version is greater or equal to - 10.4, or "no" otherwise. The fractional part of the version number may + This pattern matches "yes" if the PCRE2 version is greater or equal to + 10.4, or "no" otherwise. The fractional part of the version number may not contain more than two digits. Assertion conditions - If the condition is not in any of the above formats, it must be an - assertion. This may be a positive or negative lookahead or lookbehind - assertion. Consider this pattern, again containing non-significant + If the condition is not in any of the above formats, it must be an + assertion. This may be a positive or negative lookahead or lookbehind + assertion. Consider this pattern, again containing non-significant white space, and with the two alternatives on the second line: (?(?=[^a-z]*[a-z]) \d{2}-[a-z]{3}-\d{2} | \d{2}-\d{2}-\d{2} ) - The condition is a positive lookahead assertion that matches an - optional sequence of non-letters followed by a letter. In other words, - it tests for the presence of at least one letter in the subject. If a - letter is found, the subject is matched against the first alternative; - otherwise it is matched against the second. This pattern matches - strings in one of the two forms dd-aaa-dd or dd-dd-dd, where aaa are + The condition is a positive lookahead assertion that matches an + optional sequence of non-letters followed by a letter. In other words, + it tests for the presence of at least one letter in the subject. If a + letter is found, the subject is matched against the first alternative; + otherwise it is matched against the second. This pattern matches + strings in one of the two forms dd-aaa-dd or dd-dd-dd, where aaa are letters and dd are digits. - When an assertion that is a condition contains capturing subpatterns, - any capturing that occurs in a matching branch is retained afterwards, + When an assertion that is a condition contains capturing subpatterns, + any capturing that occurs in a matching branch is retained afterwards, for both positive and negative assertions, because matching always con- tinues after the assertion, whether it succeeds or fails. (Compare non- - conditional assertions, when captures are retained only for positive + conditional assertions, when captures are retained only for positive assertions that succeed.) COMMENTS There are two ways of including comments in patterns that are processed - by PCRE2. In both cases, the start of the comment must not be in a - character class, nor in the middle of any other sequence of related - characters such as (?: or a subpattern name or number. The characters + by PCRE2. In both cases, the start of the comment must not be in a + character class, nor in the middle of any other sequence of related + characters such as (?: or a subpattern name or number. The characters that make up a comment play no part in the pattern matching. - The sequence (?# marks the start of a comment that continues up to the - next closing parenthesis. Nested parentheses are not permitted. If the - PCRE2_EXTENDED option is set, an unescaped # character also introduces - a comment, which in this case continues to immediately after the next - newline character or character sequence in the pattern. Which charac- - ters are interpreted as newlines is controlled by an option passed to - the compiling function or by a special sequence at the start of the - pattern, as described in the section entitled "Newline conventions" - above. Note that the end of this type of comment is a literal newline - sequence in the pattern; escape sequences that happen to represent a - newline do not count. For example, consider this pattern when - PCRE2_EXTENDED is set, and the default newline convention (a single + The sequence (?# marks the start of a comment that continues up to the + next closing parenthesis. Nested parentheses are not permitted. If the + PCRE2_EXTENDED option is set, an unescaped # character also introduces + a comment, which in this case continues to immediately after the next + newline character or character sequence in the pattern. Which charac- + ters are interpreted as newlines is controlled by an option passed to + the compiling function or by a special sequence at the start of the + pattern, as described in the section entitled "Newline conventions" + above. Note that the end of this type of comment is a literal newline + sequence in the pattern; escape sequences that happen to represent a + newline do not count. For example, consider this pattern when + PCRE2_EXTENDED is set, and the default newline convention (a single linefeed character) is in force: abc #comment \n still comment - On encountering the # character, pcre2_compile() skips along, looking - for a newline in the pattern. The sequence \n is still literal at this - stage, so it does not terminate the comment. Only an actual character + On encountering the # character, pcre2_compile() skips along, looking + for a newline in the pattern. The sequence \n is still literal at this + stage, so it does not terminate the comment. Only an actual character with the code value 0x0a (the default newline) does so. RECURSIVE PATTERNS - Consider the problem of matching a string in parentheses, allowing for - unlimited nested parentheses. Without the use of recursion, the best - that can be done is to use a pattern that matches up to some fixed - depth of nesting. It is not possible to handle an arbitrary nesting + Consider the problem of matching a string in parentheses, allowing for + unlimited nested parentheses. Without the use of recursion, the best + that can be done is to use a pattern that matches up to some fixed + depth of nesting. It is not possible to handle an arbitrary nesting depth. For some time, Perl has provided a facility that allows regular expres- - sions to recurse (amongst other things). It does this by interpolating - Perl code in the expression at run time, and the code can refer to the + sions to recurse (amongst other things). It does this by interpolating + Perl code in the expression at run time, and the code can refer to the expression itself. A Perl pattern using code interpolation to solve the parentheses problem can be created like this: @@ -7870,179 +7878,179 @@ RECURSIVE PATTERNS refers recursively to the pattern in which it appears. Obviously, PCRE2 cannot support the interpolation of Perl code. - Instead, it supports special syntax for recursion of the entire pat- + Instead, it supports special syntax for recursion of the entire pat- tern, and also for individual subpattern recursion. After its introduc- - tion in PCRE1 and Python, this kind of recursion was subsequently + tion in PCRE1 and Python, this kind of recursion was subsequently introduced into Perl at release 5.10. - A special item that consists of (? followed by a number greater than - zero and a closing parenthesis is a recursive subroutine call of the - subpattern of the given number, provided that it occurs inside that - subpattern. (If not, it is a non-recursive subroutine call, which is - described in the next section.) The special item (?R) or (?0) is a + A special item that consists of (? followed by a number greater than + zero and a closing parenthesis is a recursive subroutine call of the + subpattern of the given number, provided that it occurs inside that + subpattern. (If not, it is a non-recursive subroutine call, which is + described in the next section.) The special item (?R) or (?0) is a recursive call of the entire regular expression. - This PCRE2 pattern solves the nested parentheses problem (assume the + This PCRE2 pattern solves the nested parentheses problem (assume the PCRE2_EXTENDED option is set so that white space is ignored): \( ( [^()]++ | (?R) )* \) - First it matches an opening parenthesis. Then it matches any number of - substrings which can either be a sequence of non-parentheses, or a - recursive match of the pattern itself (that is, a correctly parenthe- + First it matches an opening parenthesis. Then it matches any number of + substrings which can either be a sequence of non-parentheses, or a + recursive match of the pattern itself (that is, a correctly parenthe- sized substring). Finally there is a closing parenthesis. Note the use of a possessive quantifier to avoid backtracking into sequences of non- parentheses. - If this were part of a larger pattern, you would not want to recurse + If this were part of a larger pattern, you would not want to recurse the entire pattern, so instead you could use this: ( \( ( [^()]++ | (?1) )* \) ) - We have put the pattern into parentheses, and caused the recursion to + We have put the pattern into parentheses, and caused the recursion to refer to them instead of the whole pattern. - In a larger pattern, keeping track of parenthesis numbers can be - tricky. This is made easier by the use of relative references. Instead + In a larger pattern, keeping track of parenthesis numbers can be + tricky. This is made easier by the use of relative references. Instead of (?1) in the pattern above you can write (?-2) to refer to the second - most recently opened parentheses preceding the recursion. In other - words, a negative number counts capturing parentheses leftwards from + most recently opened parentheses preceding the recursion. In other + words, a negative number counts capturing parentheses leftwards from the point at which it is encountered. Be aware however, that if duplicate subpattern numbers are in use, rel- - ative references refer to the earliest subpattern with the appropriate + ative references refer to the earliest subpattern with the appropriate number. Consider, for example: (?|(a)|(b)) (c) (?-2) - The first two capturing groups (a) and (b) are both numbered 1, and - group (c) is number 2. When the reference (?-2) is encountered, the + The first two capturing groups (a) and (b) are both numbered 1, and + group (c) is number 2. When the reference (?-2) is encountered, the second most recently opened parentheses has the number 1, but it is the - first such group (the (a) group) to which the recursion refers. This - would be the same if an absolute reference (?1) was used. In other - words, relative references are just a shorthand for computing a group + first such group (the (a) group) to which the recursion refers. This + would be the same if an absolute reference (?1) was used. In other + words, relative references are just a shorthand for computing a group number. - It is also possible to refer to subsequently opened parentheses, by - writing references such as (?+2). However, these cannot be recursive - because the reference is not inside the parentheses that are refer- - enced. They are always non-recursive subroutine calls, as described in + It is also possible to refer to subsequently opened parentheses, by + writing references such as (?+2). However, these cannot be recursive + because the reference is not inside the parentheses that are refer- + enced. They are always non-recursive subroutine calls, as described in the next section. - An alternative approach is to use named parentheses. The Perl syntax - for this is (?&name); PCRE1's earlier syntax (?P>name) is also sup- + An alternative approach is to use named parentheses. The Perl syntax + for this is (?&name); PCRE1's earlier syntax (?P>name) is also sup- ported. We could rewrite the above example as follows: (?<pn> \( ( [^()]++ | (?&pn) )* \) ) - If there is more than one subpattern with the same name, the earliest + If there is more than one subpattern with the same name, the earliest one is used. The example pattern that we have been looking at contains nested unlim- - ited repeats, and so the use of a possessive quantifier for matching - strings of non-parentheses is important when applying the pattern to + ited repeats, and so the use of a possessive quantifier for matching + strings of non-parentheses is important when applying the pattern to strings that do not match. For example, when this pattern is applied to (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa() - it yields "no match" quickly. However, if a possessive quantifier is - not used, the match runs for a very long time indeed because there are - so many different ways the + and * repeats can carve up the subject, + it yields "no match" quickly. However, if a possessive quantifier is + not used, the match runs for a very long time indeed because there are + so many different ways the + and * repeats can carve up the subject, and all have to be tested before failure can be reported. - At the end of a match, the values of capturing parentheses are those - from the outermost level. If you want to obtain intermediate values, a + At the end of a match, the values of capturing parentheses are those + from the outermost level. If you want to obtain intermediate values, a callout function can be used (see below and the pcre2callout documenta- tion). If the pattern above is matched against (ab(cd)ef) - the value for the inner capturing parentheses (numbered 2) is "ef", - which is the last value taken on at the top level. If a capturing sub- - pattern is not matched at the top level, its final captured value is - unset, even if it was (temporarily) set at a deeper level during the + the value for the inner capturing parentheses (numbered 2) is "ef", + which is the last value taken on at the top level. If a capturing sub- + pattern is not matched at the top level, its final captured value is + unset, even if it was (temporarily) set at a deeper level during the matching process. If there are more than 15 capturing parentheses in a pattern, PCRE2 has - to obtain extra memory from the heap to store data during a recursion. - If no memory can be obtained, the match fails with the + to obtain extra memory from the heap to store data during a recursion. + If no memory can be obtained, the match fails with the PCRE2_ERROR_NOMEMORY error. - Do not confuse the (?R) item with the condition (R), which tests for - recursion. Consider this pattern, which matches text in angle brack- - ets, allowing for arbitrary nesting. Only digits are allowed in nested - brackets (that is, when recursing), whereas any characters are permit- + Do not confuse the (?R) item with the condition (R), which tests for + recursion. Consider this pattern, which matches text in angle brack- + ets, allowing for arbitrary nesting. Only digits are allowed in nested + brackets (that is, when recursing), whereas any characters are permit- ted at the outer level. < (?: (?(R) \d++ | [^<>]*+) | (?R)) * > - In this pattern, (?(R) is the start of a conditional subpattern, with - two different alternatives for the recursive and non-recursive cases. + In this pattern, (?(R) is the start of a conditional subpattern, with + two different alternatives for the recursive and non-recursive cases. The (?R) item is the actual recursive call. Differences in recursion processing between PCRE2 and Perl Some former differences between PCRE2 and Perl no longer exist. - Before release 10.30, recursion processing in PCRE2 differed from Perl - in that a recursive subpattern call was always treated as an atomic - group. That is, once it had matched some of the subject string, it was - never re-entered, even if it contained untried alternatives and there - was a subsequent matching failure. (Historical note: PCRE implemented + Before release 10.30, recursion processing in PCRE2 differed from Perl + in that a recursive subpattern call was always treated as an atomic + group. That is, once it had matched some of the subject string, it was + never re-entered, even if it contained untried alternatives and there + was a subsequent matching failure. (Historical note: PCRE implemented recursion before Perl did.) - Starting with release 10.30, recursive subroutine calls are no longer + Starting with release 10.30, recursive subroutine calls are no longer treated as atomic. That is, they can be re-entered to try unused alter- - natives if there is a matching failure later in the pattern. This is - now compatible with the way Perl works. If you want a subroutine call + natives if there is a matching failure later in the pattern. This is + now compatible with the way Perl works. If you want a subroutine call to be atomic, you must explicitly enclose it in an atomic group. - Supporting backtracking into recursions simplifies certain types of + Supporting backtracking into recursions simplifies certain types of recursive pattern. For example, this pattern matches palindromic strings: ^((.)(?1)\2|.?)$ - The second branch in the group matches a single central character in - the palindrome when there are an odd number of characters, or nothing - when there are an even number of characters, but in order to work it - has to be able to try the second case when the rest of the pattern + The second branch in the group matches a single central character in + the palindrome when there are an odd number of characters, or nothing + when there are an even number of characters, but in order to work it + has to be able to try the second case when the rest of the pattern match fails. If you want to match typical palindromic phrases, the pat- - tern has to ignore all non-word characters, which can be done like + tern has to ignore all non-word characters, which can be done like this: ^\W*+((.)\W*+(?1)\W*+\2|\W*+.?)\W*+$ - If run with the PCRE2_CASELESS option, this pattern matches phrases - such as "A man, a plan, a canal: Panama!". Note the use of the posses- - sive quantifier *+ to avoid backtracking into sequences of non-word + If run with the PCRE2_CASELESS option, this pattern matches phrases + such as "A man, a plan, a canal: Panama!". Note the use of the posses- + sive quantifier *+ to avoid backtracking into sequences of non-word characters. Without this, PCRE2 takes a great deal longer (ten times or - more) to match typical phrases, and Perl takes so long that you think + more) to match typical phrases, and Perl takes so long that you think it has gone into a loop. - Another way in which PCRE2 and Perl used to differ in their recursion - processing is in the handling of captured values. Formerly in Perl, - when a subpattern was called recursively or as a subpattern (see the - next section), it had no access to any values that were captured out- - side the recursion, whereas in PCRE2 these values can be referenced. + Another way in which PCRE2 and Perl used to differ in their recursion + processing is in the handling of captured values. Formerly in Perl, + when a subpattern was called recursively or as a subpattern (see the + next section), it had no access to any values that were captured out- + side the recursion, whereas in PCRE2 these values can be referenced. Consider this pattern: ^(.)(\1|a(?2)) - This pattern matches "bab". The first capturing parentheses match "b", - then in the second group, when the back reference \1 fails to match - "b", the second alternative matches "a" and then recurses. In the - recursion, \1 does now match "b" and so the whole match succeeds. This - match used to fail in Perl, but in later versions (I tried 5.024) it + This pattern matches "bab". The first capturing parentheses match "b", + then in the second group, when the back reference \1 fails to match + "b", the second alternative matches "a" and then recurses. In the + recursion, \1 does now match "b" and so the whole match succeeds. This + match used to fail in Perl, but in later versions (I tried 5.024) it now works. SUBPATTERNS AS SUBROUTINES - If the syntax for a recursive subpattern call (either by number or by - name) is used outside the parentheses to which it refers, it operates - like a subroutine in a programming language. The called subpattern may - be defined before or after the reference. A numbered reference can be + If the syntax for a recursive subpattern call (either by number or by + name) is used outside the parentheses to which it refers, it operates + like a subroutine in a programming language. The called subpattern may + be defined before or after the reference. A numbered reference can be absolute or relative, as in these examples: (...(absolute)...)...(?2)... @@ -8053,102 +8061,102 @@ SUBPATTERNS AS SUBROUTINES (sens|respons)e and \1ibility - matches "sense and sensibility" and "response and responsibility", but + matches "sense and sensibility" and "response and responsibility", but not "sense and responsibility". If instead the pattern (sens|respons)e and (?1)ibility - is used, it does match "sense and responsibility" as well as the other - two strings. Another example is given in the discussion of DEFINE + is used, it does match "sense and responsibility" as well as the other + two strings. Another example is given in the discussion of DEFINE above. - Like recursions, subroutine calls used to be treated as atomic, but - this changed at PCRE2 release 10.30, so backtracking into subroutine - calls can now occur. However, any capturing parentheses that are set + Like recursions, subroutine calls used to be treated as atomic, but + this changed at PCRE2 release 10.30, so backtracking into subroutine + calls can now occur. However, any capturing parentheses that are set during the subroutine call revert to their previous values afterwards. - Processing options such as case-independence are fixed when a subpat- - tern is defined, so if it is used as a subroutine, such options cannot + Processing options such as case-independence are fixed when a subpat- + tern is defined, so if it is used as a subroutine, such options cannot be changed for different calls. For example, consider this pattern: (abc)(?i:(?-1)) - It matches "abcabc". It does not match "abcABC" because the change of + It matches "abcabc". It does not match "abcABC" because the change of processing option does not affect the called subpattern. ONIGURUMA SUBROUTINE SYNTAX - For compatibility with Oniguruma, the non-Perl syntax \g followed by a + For compatibility with Oniguruma, the non-Perl syntax \g followed by a name or a number enclosed either in angle brackets or single quotes, is - an alternative syntax for referencing a subpattern as a subroutine, - possibly recursively. Here are two of the examples used above, rewrit- + an alternative syntax for referencing a subpattern as a subroutine, + possibly recursively. Here are two of the examples used above, rewrit- ten using this syntax: (?<pn> \( ( (?>[^()]+) | \g<pn> )* \) ) (sens|respons)e and \g'1'ibility - PCRE2 supports an extension to Oniguruma: if a number is preceded by a + PCRE2 supports an extension to Oniguruma: if a number is preceded by a plus or a minus sign it is taken as a relative reference. For example: (abc)(?i:\g<-1>) - Note that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are not - synonymous. The former is a back reference; the latter is a subroutine + Note that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are not + synonymous. The former is a back reference; the latter is a subroutine call. CALLOUTS Perl has a feature whereby using the sequence (?{...}) causes arbitrary - Perl code to be obeyed in the middle of matching a regular expression. + Perl code to be obeyed in the middle of matching a regular expression. This makes it possible, amongst other things, to extract different sub- strings that match the same pair of parentheses when there is a repeti- tion. - PCRE2 provides a similar feature, but of course it cannot obey arbi- - trary Perl code. The feature is called "callout". The caller of PCRE2 - provides an external function by putting its entry point in a match - context using the function pcre2_set_callout(), and then passing that - context to pcre2_match() or pcre2_dfa_match(). If no match context is + PCRE2 provides a similar feature, but of course it cannot obey arbi- + trary Perl code. The feature is called "callout". The caller of PCRE2 + provides an external function by putting its entry point in a match + context using the function pcre2_set_callout(), and then passing that + context to pcre2_match() or pcre2_dfa_match(). If no match context is passed, or if the callout entry point is set to NULL, callouts are dis- abled. - Within a regular expression, (?C<arg>) indicates a point at which the - external function is to be called. There are two kinds of callout: - those with a numerical argument and those with a string argument. (?C) - on its own with no argument is treated as (?C0). A numerical argument - allows the application to distinguish between different callouts. - String arguments were added for release 10.20 to make it possible for - script languages that use PCRE2 to embed short scripts within patterns + Within a regular expression, (?C<arg>) indicates a point at which the + external function is to be called. There are two kinds of callout: + those with a numerical argument and those with a string argument. (?C) + on its own with no argument is treated as (?C0). A numerical argument + allows the application to distinguish between different callouts. + String arguments were added for release 10.20 to make it possible for + script languages that use PCRE2 to embed short scripts within patterns in a similar way to Perl. During matching, when PCRE2 reaches a callout point, the external func- - tion is called. It is provided with the number or string argument of - the callout, the position in the pattern, and one item of data that is + tion is called. It is provided with the number or string argument of + the callout, the position in the pattern, and one item of data that is also set in the match block. The callout function may cause matching to proceed, to backtrack, or to fail. - By default, PCRE2 implements a number of optimizations at matching - time, and one side-effect is that sometimes callouts are skipped. If - you need all possible callouts to happen, you need to set options that - disable the relevant optimizations. More details, including a complete - description of the programming interface to the callout function, are + By default, PCRE2 implements a number of optimizations at matching + time, and one side-effect is that sometimes callouts are skipped. If + you need all possible callouts to happen, you need to set options that + disable the relevant optimizations. More details, including a complete + description of the programming interface to the callout function, are given in the pcre2callout documentation. Callouts with numerical arguments - If you just want to have a means of identifying different callout - points, put a number less than 256 after the letter C. For example, + If you just want to have a means of identifying different callout + points, put a number less than 256 after the letter C. For example, this pattern has two callout points: (?C1)abc(?C2)def - If the PCRE2_AUTO_CALLOUT flag is passed to pcre2_compile(), numerical - callouts are automatically installed before each item in the pattern. - They are all numbered 255. If there is a conditional group in the pat- + If the PCRE2_AUTO_CALLOUT flag is passed to pcre2_compile(), numerical + callouts are automatically installed before each item in the pattern. + They are all numbered 255. If there is a conditional group in the pat- tern whose condition is an assertion, an additional callout is inserted - just before the condition. An explicit callout may also be set at this + just before the condition. An explicit callout may also be set at this position, as in this example: (?(?C9)(?=a)abc|def) @@ -8158,60 +8166,60 @@ CALLOUTS Callouts with string arguments - A delimited string may be used instead of a number as a callout argu- - ment. The starting delimiter must be one of ` ' " ^ % # $ { and the + A delimited string may be used instead of a number as a callout argu- + ment. The starting delimiter must be one of ` ' " ^ % # $ { and the ending delimiter is the same as the start, except for {, where the end- - ing delimiter is }. If the ending delimiter is needed within the + ing delimiter is }. If the ending delimiter is needed within the string, it must be doubled. For example: (?C'ab ''c'' d')xyz(?C{any text})pqr - The doubling is removed before the string is passed to the callout + The doubling is removed before the string is passed to the callout function. BACKTRACKING CONTROL - There are a number of special "Backtracking Control Verbs" (to use - Perl's terminology) that modify the behaviour of backtracking during - matching. They are generally of the form (*VERB) or (*VERB:NAME). Some - verbs take either form, possibly behaving differently depending on + There are a number of special "Backtracking Control Verbs" (to use + Perl's terminology) that modify the behaviour of backtracking during + matching. They are generally of the form (*VERB) or (*VERB:NAME). Some + verbs take either form, possibly behaving differently depending on whether or not a name is present. - By default, for compatibility with Perl, a name is any sequence of + By default, for compatibility with Perl, a name is any sequence of characters that does not include a closing parenthesis. The name is not - processed in any way, and it is not possible to include a closing - parenthesis in the name. This can be changed by setting the - PCRE2_ALT_VERBNAMES option, but the result is no longer Perl-compati- + processed in any way, and it is not possible to include a closing + parenthesis in the name. This can be changed by setting the + PCRE2_ALT_VERBNAMES option, but the result is no longer Perl-compati- ble. - When PCRE2_ALT_VERBNAMES is set, backslash processing is applied to - verb names and only an unescaped closing parenthesis terminates the - name. However, the only backslash items that are permitted are \Q, \E, - and sequences such as \x{100} that define character code points. Char- + When PCRE2_ALT_VERBNAMES is set, backslash processing is applied to + verb names and only an unescaped closing parenthesis terminates the + name. However, the only backslash items that are permitted are \Q, \E, + and sequences such as \x{100} that define character code points. Char- acter type escapes such as \d are faulted. A closing parenthesis can be included in a name either as \) or between - \Q and \E. In addition to backslash processing, if the PCRE2_EXTENDED - option is also set, unescaped whitespace in verb names is skipped, and - #-comments are recognized, exactly as in the rest of the pattern. + \Q and \E. In addition to backslash processing, if the PCRE2_EXTENDED + option is also set, unescaped whitespace in verb names is skipped, and + #-comments are recognized, exactly as in the rest of the pattern. PCRE2_EXTENDED does not affect verb names unless PCRE2_ALT_VERBNAMES is also set. - The maximum length of a name is 255 in the 8-bit library and 65535 in - the 16-bit and 32-bit libraries. If the name is empty, that is, if the - closing parenthesis immediately follows the colon, the effect is as if + The maximum length of a name is 255 in the 8-bit library and 65535 in + the 16-bit and 32-bit libraries. If the name is empty, that is, if the + closing parenthesis immediately follows the colon, the effect is as if the colon were not there. Any number of these verbs may occur in a pat- tern. - Since these verbs are specifically related to backtracking, most of - them can be used only when the pattern is to be matched using the tra- + Since these verbs are specifically related to backtracking, most of + them can be used only when the pattern is to be matched using the tra- ditional matching function, because that uses a backtracking algorithm. - With the exception of (*FAIL), which behaves like a failing negative + With the exception of (*FAIL), which behaves like a failing negative assertion, the backtracking control verbs cause an error if encountered by the DFA matching function. - The behaviour of these verbs in repeated groups, assertions, and in + The behaviour of these verbs in repeated groups, assertions, and in subpatterns called as subroutines (whether or not recursively) is docu- mented below. @@ -8219,71 +8227,71 @@ BACKTRACKING CONTROL PCRE2 contains some optimizations that are used to speed up matching by running some checks at the start of each match attempt. For example, it - may know the minimum length of matching subject, or that a particular + may know the minimum length of matching subject, or that a particular character must be present. When one of these optimizations bypasses the - running of a match, any included backtracking verbs will not, of + running of a match, any included backtracking verbs will not, of course, be processed. You can suppress the start-of-match optimizations - by setting the PCRE2_NO_START_OPTIMIZE option when calling pcre2_com- - pile(), or by starting the pattern with (*NO_START_OPT). There is more + by setting the PCRE2_NO_START_OPTIMIZE option when calling pcre2_com- + pile(), or by starting the pattern with (*NO_START_OPT). There is more discussion of this option in the section entitled "Compiling a pattern" in the pcre2api documentation. - Experiments with Perl suggest that it too has similar optimizations, + Experiments with Perl suggest that it too has similar optimizations, sometimes leading to anomalous results. Verbs that act immediately - The following verbs act as soon as they are encountered. They may not + The following verbs act as soon as they are encountered. They may not be followed by a name. (*ACCEPT) - This verb causes the match to end successfully, skipping the remainder - of the pattern. However, when it is inside a subpattern that is called - as a subroutine, only that subpattern is ended successfully. Matching + This verb causes the match to end successfully, skipping the remainder + of the pattern. However, when it is inside a subpattern that is called + as a subroutine, only that subpattern is ended successfully. Matching then continues at the outer level. If (*ACCEPT) in triggered in a posi- - tive assertion, the assertion succeeds; in a negative assertion, the + tive assertion, the assertion succeeds; in a negative assertion, the assertion fails. - If (*ACCEPT) is inside capturing parentheses, the data so far is cap- + If (*ACCEPT) is inside capturing parentheses, the data so far is cap- tured. For example: A((?:A|B(*ACCEPT)|C)D) - This matches "AB", "AAD", or "ACD"; when it matches "AB", "B" is cap- + This matches "AB", "AAD", or "ACD"; when it matches "AB", "B" is cap- tured by the outer parentheses. (*FAIL) or (*F) - This verb causes a matching failure, forcing backtracking to occur. It - is equivalent to (?!) but easier to read. The Perl documentation notes - that it is probably useful only when combined with (?{}) or (??{}). - Those are, of course, Perl features that are not present in PCRE2. The - nearest equivalent is the callout feature, as for example in this pat- + This verb causes a matching failure, forcing backtracking to occur. It + is equivalent to (?!) but easier to read. The Perl documentation notes + that it is probably useful only when combined with (?{}) or (??{}). + Those are, of course, Perl features that are not present in PCRE2. The + nearest equivalent is the callout feature, as for example in this pat- tern: a+(?C)(*FAIL) - A match with the string "aaaa" always fails, but the callout is taken + A match with the string "aaaa" always fails, but the callout is taken before each backtrack happens (in this example, 10 times). Recording which path was taken - There is one verb whose main purpose is to track how a match was - arrived at, though it also has a secondary use in conjunction with + There is one verb whose main purpose is to track how a match was + arrived at, though it also has a secondary use in conjunction with advancing the match starting point (see (*SKIP) below). (*MARK:NAME) or (*:NAME) - A name is always required with this verb. There may be as many - instances of (*MARK) as you like in a pattern, and their names do not + A name is always required with this verb. There may be as many + instances of (*MARK) as you like in a pattern, and their names do not have to be unique. - When a match succeeds, the name of the last-encountered (*MARK:NAME), - (*PRUNE:NAME), or (*THEN:NAME) on the matching path is passed back to - the caller as described in the section entitled "Other information - about the match" in the pcre2api documentation. Here is an example of - pcre2test output, where the "mark" modifier requests the retrieval and + When a match succeeds, the name of the last-encountered (*MARK:NAME), + (*PRUNE:NAME), or (*THEN:NAME) on the matching path is passed back to + the caller as described in the section entitled "Other information + about the match" in the pcre2api documentation. Here is an example of + pcre2test output, where the "mark" modifier requests the retrieval and outputting of (*MARK) data: re> /X(*MARK:A)Y|X(*MARK:B)Z/mark @@ -8295,72 +8303,72 @@ BACKTRACKING CONTROL MK: B The (*MARK) name is tagged with "MK:" in this output, and in this exam- - ple it indicates which of the two alternatives matched. This is a more - efficient way of obtaining this information than putting each alterna- + ple it indicates which of the two alternatives matched. This is a more + efficient way of obtaining this information than putting each alterna- tive in its own capturing parentheses. - If a verb with a name is encountered in a positive assertion that is - true, the name is recorded and passed back if it is the last-encoun- + If a verb with a name is encountered in a positive assertion that is + true, the name is recorded and passed back if it is the last-encoun- tered. This does not happen for negative assertions or failing positive assertions. - After a partial match or a failed match, the last encountered name in + After a partial match or a failed match, the last encountered name in the entire match process is returned. For example: re> /X(*MARK:A)Y|X(*MARK:B)Z/mark data> XP No match, mark = B - Note that in this unanchored example the mark is retained from the + Note that in this unanchored example the mark is retained from the match attempt that started at the letter "X" in the subject. Subsequent match attempts starting at "P" and then with an empty string do not get as far as the (*MARK) item, but nevertheless do not reset it. - If you are interested in (*MARK) values after failed matches, you - should probably set the PCRE2_NO_START_OPTIMIZE option (see above) to + If you are interested in (*MARK) values after failed matches, you + should probably set the PCRE2_NO_START_OPTIMIZE option (see above) to ensure that the match is always attempted. Verbs that act after backtracking The following verbs do nothing when they are encountered. Matching con- - tinues with what follows, but if there is no subsequent match, causing - a backtrack to the verb, a failure is forced. That is, backtracking - cannot pass to the left of the verb. However, when one of these verbs - appears inside an atomic group or in an assertion that is true, its - effect is confined to that group, because once the group has been - matched, there is never any backtracking into it. In this situation, - backtracking has to jump to the left of the entire atomic group or + tinues with what follows, but if there is no subsequent match, causing + a backtrack to the verb, a failure is forced. That is, backtracking + cannot pass to the left of the verb. However, when one of these verbs + appears inside an atomic group or in an assertion that is true, its + effect is confined to that group, because once the group has been + matched, there is never any backtracking into it. In this situation, + backtracking has to jump to the left of the entire atomic group or assertion. - These verbs differ in exactly what kind of failure occurs when back- - tracking reaches them. The behaviour described below is what happens - when the verb is not in a subroutine or an assertion. Subsequent sec- + These verbs differ in exactly what kind of failure occurs when back- + tracking reaches them. The behaviour described below is what happens + when the verb is not in a subroutine or an assertion. Subsequent sec- tions cover these special cases. (*COMMIT) - This verb, which may not be followed by a name, causes the whole match + This verb, which may not be followed by a name, causes the whole match to fail outright if there is a later matching failure that causes back- - tracking to reach it. Even if the pattern is unanchored, no further + tracking to reach it. Even if the pattern is unanchored, no further attempts to find a match by advancing the starting point take place. If - (*COMMIT) is the only backtracking verb that is encountered, once it - has been passed pcre2_match() is committed to finding a match at the + (*COMMIT) is the only backtracking verb that is encountered, once it + has been passed pcre2_match() is committed to finding a match at the current starting point, or not at all. For example: a+(*COMMIT)b - This matches "xxaab" but not "aacaab". It can be thought of as a kind + This matches "xxaab" but not "aacaab". It can be thought of as a kind of dynamic anchor, or "I've started, so I must finish." The name of the - most recently passed (*MARK) in the path is passed back when (*COMMIT) + most recently passed (*MARK) in the path is passed back when (*COMMIT) forces a match failure. - If there is more than one backtracking verb in a pattern, a different - one that follows (*COMMIT) may be triggered first, so merely passing + If there is more than one backtracking verb in a pattern, a different + one that follows (*COMMIT) may be triggered first, so merely passing (*COMMIT) during a match does not always guarantee that a match must be at this starting point. - Note that (*COMMIT) at the start of a pattern is not the same as an - anchor, unless PCRE2's start-of-match optimizations are turned off, as + Note that (*COMMIT) at the start of a pattern is not the same as an + anchor, unless PCRE2's start-of-match optimizations are turned off, as shown in this output from pcre2test: re> /(*COMMIT)abc/ @@ -8371,213 +8379,213 @@ BACKTRACKING CONTROL data> xyzabc No match - For the first pattern, PCRE2 knows that any match must start with "a", - so the optimization skips along the subject to "a" before applying the - pattern to the first set of data. The match attempt then succeeds. The - second pattern disables the optimization that skips along to the first - character. The pattern is now applied starting at "x", and so the - (*COMMIT) causes the match to fail without trying any other starting + For the first pattern, PCRE2 knows that any match must start with "a", + so the optimization skips along the subject to "a" before applying the + pattern to the first set of data. The match attempt then succeeds. The + second pattern disables the optimization that skips along to the first + character. The pattern is now applied starting at "x", and so the + (*COMMIT) causes the match to fail without trying any other starting points. (*PRUNE) or (*PRUNE:NAME) - This verb causes the match to fail at the current starting position in + This verb causes the match to fail at the current starting position in the subject if there is a later matching failure that causes backtrack- - ing to reach it. If the pattern is unanchored, the normal "bumpalong" - advance to the next starting character then happens. Backtracking can - occur as usual to the left of (*PRUNE), before it is reached, or when - matching to the right of (*PRUNE), but if there is no match to the - right, backtracking cannot cross (*PRUNE). In simple cases, the use of - (*PRUNE) is just an alternative to an atomic group or possessive quan- + ing to reach it. If the pattern is unanchored, the normal "bumpalong" + advance to the next starting character then happens. Backtracking can + occur as usual to the left of (*PRUNE), before it is reached, or when + matching to the right of (*PRUNE), but if there is no match to the + right, backtracking cannot cross (*PRUNE). In simple cases, the use of + (*PRUNE) is just an alternative to an atomic group or possessive quan- tifier, but there are some uses of (*PRUNE) that cannot be expressed in - any other way. In an anchored pattern (*PRUNE) has the same effect as + any other way. In an anchored pattern (*PRUNE) has the same effect as (*COMMIT). The behaviour of (*PRUNE:NAME) is not the same as (*MARK:NAME)(*PRUNE). It is like (*MARK:NAME) in that the name is remembered for passing back - to the caller. However, (*SKIP:NAME) searches only for names set with + to the caller. However, (*SKIP:NAME) searches only for names set with (*MARK), ignoring those set by (*PRUNE) or (*THEN). (*SKIP) - This verb, when given without a name, is like (*PRUNE), except that if - the pattern is unanchored, the "bumpalong" advance is not to the next + This verb, when given without a name, is like (*PRUNE), except that if + the pattern is unanchored, the "bumpalong" advance is not to the next character, but to the position in the subject where (*SKIP) was encoun- - tered. (*SKIP) signifies that whatever text was matched leading up to + tered. (*SKIP) signifies that whatever text was matched leading up to it cannot be part of a successful match. Consider: a+(*SKIP)b - If the subject is "aaaac...", after the first match attempt fails - (starting at the first character in the string), the starting point + If the subject is "aaaac...", after the first match attempt fails + (starting at the first character in the string), the starting point skips on to start the next attempt at "c". Note that a possessive quan- - tifer does not have the same effect as this example; although it would - suppress backtracking during the first match attempt, the second - attempt would start at the second character instead of skipping on to + tifer does not have the same effect as this example; although it would + suppress backtracking during the first match attempt, the second + attempt would start at the second character instead of skipping on to "c". (*SKIP:NAME) When (*SKIP) has an associated name, its behaviour is modified. When it is triggered, the previous path through the pattern is searched for the - most recent (*MARK) that has the same name. If one is found, the + most recent (*MARK) that has the same name. If one is found, the "bumpalong" advance is to the subject position that corresponds to that (*MARK) instead of to where (*SKIP) was encountered. If no (*MARK) with a matching name is found, the (*SKIP) is ignored. - Note that (*SKIP:NAME) searches only for names set by (*MARK:NAME). It + Note that (*SKIP:NAME) searches only for names set by (*MARK:NAME). It ignores names that are set by (*PRUNE:NAME) or (*THEN:NAME). (*THEN) or (*THEN:NAME) - This verb causes a skip to the next innermost alternative when back- - tracking reaches it. That is, it cancels any further backtracking - within the current alternative. Its name comes from the observation + This verb causes a skip to the next innermost alternative when back- + tracking reaches it. That is, it cancels any further backtracking + within the current alternative. Its name comes from the observation that it can be used for a pattern-based if-then-else block: ( COND1 (*THEN) FOO | COND2 (*THEN) BAR | COND3 (*THEN) BAZ ) ... - If the COND1 pattern matches, FOO is tried (and possibly further items - after the end of the group if FOO succeeds); on failure, the matcher - skips to the second alternative and tries COND2, without backtracking - into COND1. If that succeeds and BAR fails, COND3 is tried. If subse- - quently BAZ fails, there are no more alternatives, so there is a back- - track to whatever came before the entire group. If (*THEN) is not + If the COND1 pattern matches, FOO is tried (and possibly further items + after the end of the group if FOO succeeds); on failure, the matcher + skips to the second alternative and tries COND2, without backtracking + into COND1. If that succeeds and BAR fails, COND3 is tried. If subse- + quently BAZ fails, there are no more alternatives, so there is a back- + track to whatever came before the entire group. If (*THEN) is not inside an alternation, it acts like (*PRUNE). - The behaviour of (*THEN:NAME) is the not the same as - (*MARK:NAME)(*THEN). It is like (*MARK:NAME) in that the name is - remembered for passing back to the caller. However, (*SKIP:NAME) - searches only for names set with (*MARK), ignoring those set by + The behaviour of (*THEN:NAME) is the not the same as + (*MARK:NAME)(*THEN). It is like (*MARK:NAME) in that the name is + remembered for passing back to the caller. However, (*SKIP:NAME) + searches only for names set with (*MARK), ignoring those set by (*PRUNE) and (*THEN). - A subpattern that does not contain a | character is just a part of the - enclosing alternative; it is not a nested alternation with only one - alternative. The effect of (*THEN) extends beyond such a subpattern to - the enclosing alternative. Consider this pattern, where A, B, etc. are - complex pattern fragments that do not contain any | characters at this + A subpattern that does not contain a | character is just a part of the + enclosing alternative; it is not a nested alternation with only one + alternative. The effect of (*THEN) extends beyond such a subpattern to + the enclosing alternative. Consider this pattern, where A, B, etc. are + complex pattern fragments that do not contain any | characters at this level: A (B(*THEN)C) | D - If A and B are matched, but there is a failure in C, matching does not + If A and B are matched, but there is a failure in C, matching does not backtrack into A; instead it moves to the next alternative, that is, D. - However, if the subpattern containing (*THEN) is given an alternative, + However, if the subpattern containing (*THEN) is given an alternative, it behaves differently: A (B(*THEN)C | (*FAIL)) | D - The effect of (*THEN) is now confined to the inner subpattern. After a + The effect of (*THEN) is now confined to the inner subpattern. After a failure in C, matching moves to (*FAIL), which causes the whole subpat- - tern to fail because there are no more alternatives to try. In this + tern to fail because there are no more alternatives to try. In this case, matching does now backtrack into A. - Note that a conditional subpattern is not considered as having two - alternatives, because only one is ever used. In other words, the | + Note that a conditional subpattern is not considered as having two + alternatives, because only one is ever used. In other words, the | character in a conditional subpattern has a different meaning. Ignoring white space, consider: ^.*? (?(?=a) a | b(*THEN)c ) - If the subject is "ba", this pattern does not match. Because .*? is - ungreedy, it initially matches zero characters. The condition (?=a) - then fails, the character "b" is matched, but "c" is not. At this - point, matching does not backtrack to .*? as might perhaps be expected - from the presence of the | character. The conditional subpattern is + If the subject is "ba", this pattern does not match. Because .*? is + ungreedy, it initially matches zero characters. The condition (?=a) + then fails, the character "b" is matched, but "c" is not. At this + point, matching does not backtrack to .*? as might perhaps be expected + from the presence of the | character. The conditional subpattern is part of the single alternative that comprises the whole pattern, and so - the match fails. (If there was a backtrack into .*?, allowing it to + the match fails. (If there was a backtrack into .*?, allowing it to match "b", the match would succeed.) - The verbs just described provide four different "strengths" of control + The verbs just described provide four different "strengths" of control when subsequent matching fails. (*THEN) is the weakest, carrying on the - match at the next alternative. (*PRUNE) comes next, failing the match - at the current starting position, but allowing an advance to the next - character (for an unanchored pattern). (*SKIP) is similar, except that + match at the next alternative. (*PRUNE) comes next, failing the match + at the current starting position, but allowing an advance to the next + character (for an unanchored pattern). (*SKIP) is similar, except that the advance may be more than one character. (*COMMIT) is the strongest, causing the entire match to fail. More than one backtracking verb - If more than one backtracking verb is present in a pattern, the one - that is backtracked onto first acts. For example, consider this pat- + If more than one backtracking verb is present in a pattern, the one + that is backtracked onto first acts. For example, consider this pat- tern, where A, B, etc. are complex pattern fragments: (A(*COMMIT)B(*THEN)C|ABD) - If A matches but B fails, the backtrack to (*COMMIT) causes the entire + If A matches but B fails, the backtrack to (*COMMIT) causes the entire match to fail. However, if A and B match, but C fails, the backtrack to - (*THEN) causes the next alternative (ABD) to be tried. This behaviour - is consistent, but is not always the same as Perl's. It means that if - two or more backtracking verbs appear in succession, all the the last + (*THEN) causes the next alternative (ABD) to be tried. This behaviour + is consistent, but is not always the same as Perl's. It means that if + two or more backtracking verbs appear in succession, all the the last of them has no effect. Consider this example: ...(*COMMIT)(*PRUNE)... If there is a matching failure to the right, backtracking onto (*PRUNE) - causes it to be triggered, and its action is taken. There can never be + causes it to be triggered, and its action is taken. There can never be a backtrack onto (*COMMIT). Backtracking verbs in repeated groups - PCRE2 differs from Perl in its handling of backtracking verbs in + PCRE2 differs from Perl in its handling of backtracking verbs in repeated groups. For example, consider: /(a(*COMMIT)b)+ac/ - If the subject is "abac", Perl matches, but PCRE2 fails because the + If the subject is "abac", Perl matches, but PCRE2 fails because the (*COMMIT) in the second repeat of the group acts. Backtracking verbs in assertions - (*FAIL) in any assertion has its normal effect: it forces an immediate - backtrack. The behaviour of the other backtracking verbs depends on - whether or not the assertion is standalone or acting as the condition + (*FAIL) in any assertion has its normal effect: it forces an immediate + backtrack. The behaviour of the other backtracking verbs depends on + whether or not the assertion is standalone or acting as the condition in a conditional subpattern. - (*ACCEPT) in a standalone positive assertion causes the assertion to - succeed without any further processing; captured strings are retained. - In a standalone negative assertion, (*ACCEPT) causes the assertion to + (*ACCEPT) in a standalone positive assertion causes the assertion to + succeed without any further processing; captured strings are retained. + In a standalone negative assertion, (*ACCEPT) causes the assertion to fail without any further processing; captured substrings are discarded. - If the assertion is a condition, (*ACCEPT) causes the condition to be - true for a positive assertion and false for a negative one; captured + If the assertion is a condition, (*ACCEPT) causes the condition to be + true for a positive assertion and false for a negative one; captured substrings are retained in both cases. - The effect of (*THEN) is not allowed to escape beyond an assertion. If - there are no more branches to try, (*THEN) causes a positive assertion + The effect of (*THEN) is not allowed to escape beyond an assertion. If + there are no more branches to try, (*THEN) causes a positive assertion to be false, and a negative assertion to be true. - The other backtracking verbs are not treated specially if they appear - in a standalone positive assertion. In a conditional positive asser- + The other backtracking verbs are not treated specially if they appear + in a standalone positive assertion. In a conditional positive asser- tion, backtracking into (*COMMIT), (*SKIP), or (*PRUNE) causes the con- - dition to be false. However, for both standalone and conditional nega- - tive assertions, backtracking into (*COMMIT), (*SKIP), or (*PRUNE) + dition to be false. However, for both standalone and conditional nega- + tive assertions, backtracking into (*COMMIT), (*SKIP), or (*PRUNE) causes the assertion to be true, without considering any further alter- native branches. Backtracking verbs in subroutines - These behaviours occur whether or not the subpattern is called recur- + These behaviours occur whether or not the subpattern is called recur- sively. Perl's treatment of subroutines is different in some cases. - (*FAIL) in a subpattern called as a subroutine has its normal effect: + (*FAIL) in a subpattern called as a subroutine has its normal effect: it forces an immediate backtrack. - (*ACCEPT) in a subpattern called as a subroutine causes the subroutine - match to succeed without any further processing. Matching then contin- + (*ACCEPT) in a subpattern called as a subroutine causes the subroutine + match to succeed without any further processing. Matching then contin- ues after the subroutine call. (*COMMIT), (*SKIP), and (*PRUNE) in a subpattern called as a subroutine cause the subroutine match to fail. - (*THEN) skips to the next alternative in the innermost enclosing group - within the subpattern that has alternatives. If there is no such group + (*THEN) skips to the next alternative in the innermost enclosing group + within the subpattern that has alternatives. If there is no such group within the subpattern, (*THEN) causes the subroutine match to fail. SEE ALSO - pcre2api(3), pcre2callout(3), pcre2matching(3), pcre2syntax(3), + pcre2api(3), pcre2callout(3), pcre2matching(3), pcre2syntax(3), pcre2(3). @@ -8590,7 +8598,7 @@ AUTHOR REVISION - Last updated: 11 April 2017 + Last updated: 18 April 2017 Copyright (c) 1997-2017 University of Cambridge. ------------------------------------------------------------------------------ @@ -9643,7 +9651,8 @@ OPTION SETTING (?m) multiline (?s) single line (dotall) (?U) default ungreedy (lazy) - (?x) extended (ignore white space) + (?x) extended: ignore white space except in classes + (?xx) as (?x) but also ignore space and tab in classes (?-...) unset option(s) The following are recognized only at the very start of a pattern or @@ -9807,7 +9816,7 @@ AUTHOR REVISION - Last updated: 31 March 2017 + Last updated: 18 April 2017 Copyright (c) 1997-2017 University of Cambridge. ------------------------------------------------------------------------------ diff --git a/doc/pcre2api.3 b/doc/pcre2api.3 index 8803c48..6006f04 100644 --- a/doc/pcre2api.3 +++ b/doc/pcre2api.3 @@ -1,4 +1,4 @@ -.TH PCRE2API 3 "14 April 2017" "PCRE2 10.30" +.TH PCRE2API 3 "17 April 2017" "PCRE2 10.30" .SH NAME PCRE2 - Perl-compatible regular expressions (revised API) .sp @@ -1348,6 +1348,13 @@ sequence at the start of the pattern, as described in the section entitled in the \fBpcre2pattern\fP documentation. A default is defined when PCRE2 is built. .sp + PCRE2_EXTENDED_MORE +.sp +This option has the effect of PCRE2_EXTENDED, but, in addition, space and +horizontal tab characters are also ignored inside a character class. +PCRE2_EXTENDED_MORE is equivalent to Perl's 5.26 /xx option, and it can be +changed within a pattern by a (?xx) option setting. +.sp PCRE2_FIRSTLINE .sp If this option is set, an unanchored pattern is required to match before or at @@ -3395,6 +3402,6 @@ Cambridge, England. .rs .sp .nf -Last updated: 14 April 2017 +Last updated: 17 April 2017 Copyright (c) 1997-2017 University of Cambridge. .fi diff --git a/doc/pcre2compat.3 b/doc/pcre2compat.3 index f6c1bb4..b3722df 100644 --- a/doc/pcre2compat.3 +++ b/doc/pcre2compat.3 @@ -1,4 +1,4 @@ -.TH PCRE2COMPAT 3 "17 April 2017" "PCRE2 10.30" +.TH PCRE2COMPAT 3 "18 April 2017" "PCRE2 10.30" .SH NAME PCRE2 - Perl-compatible regular expressions (revised API) .SH "DIFFERENCES BETWEEN PCRE2 AND PERL" @@ -165,13 +165,11 @@ different way and is not Perl-compatible. (l) PCRE2 recognizes some special sequences such as (*CR) or (*NO_JIT) at the start of a pattern that set overall options that cannot be changed within the pattern. -.sp -18. The following new Perl 5.26 constructs are not yet supported in PCRE2: -.sp -(a) The Perl /a modifier restricts /d numbers to pure ascii, the new /aa -modifier restricts /i case-insensitive matching to pure ascii also, ignoring -unicode rules. This separation cannot be represented with PCRE2_UTF. -.sp +.P +18. The Perl /a modifier restricts /d numbers to pure ascii, and the /aa +modifier restricts /i case-insensitive matching to pure ascii, ignoring Unicode +rules. This separation cannot be represented with PCRE2_UCP. +.P 19. Perl has different limits than PCRE2. See the .\" HREF \fBpcre2limit\fP @@ -196,6 +194,6 @@ Cambridge, England. .rs .sp .nf -Last updated: 17 April 2017 +Last updated: 18 April 2017 Copyright (c) 1997-2017 University of Cambridge. .fi diff --git a/doc/pcre2pattern.3 b/doc/pcre2pattern.3 index 9a3257f..8978530 100644 --- a/doc/pcre2pattern.3 +++ b/doc/pcre2pattern.3 @@ -1,4 +1,4 @@ -.TH PCRE2PATTERN 3 "11 April 2017" "PCRE2 10.30" +.TH PCRE2PATTERN 3 "18 April 2017" "PCRE2 10.30" .SH NAME PCRE2 - Perl-compatible regular expressions (revised API) .SH "PCRE2 REGULAR EXPRESSION DETAILS" @@ -1542,20 +1542,24 @@ alternative in the subpattern. .SH "INTERNAL OPTION SETTING" .rs .sp -The settings of the PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL, and -PCRE2_EXTENDED options (which are Perl-compatible) can be changed from within -the pattern by a sequence of Perl option letters enclosed between "(?" and ")". -The option letters are +The settings of the PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL, +PCRE2_EXTENDED, and PCRE2_EXTENDED_MORE options (which are Perl-compatible) can +be changed from within the pattern by a sequence of Perl option letters +enclosed between "(?" and ")". The option letters are .sp i for PCRE2_CASELESS m for PCRE2_MULTILINE s for PCRE2_DOTALL x for PCRE2_EXTENDED + xx for PCRE2_EXTENDED_MORE .sp For example, (?im) sets caseless, multiline matching. It is also possible to -unset these options by preceding the letter with a hyphen, and a combined -setting and unsetting such as (?im-sx), which sets PCRE2_CASELESS and -PCRE2_MULTILINE while unsetting PCRE2_DOTALL and PCRE2_EXTENDED, is also +unset these options by preceding the letter with a hyphen. The two "extended" +options are not independent; unsetting either one cancels the effects of both +of them. +.P +A combined setting and unsetting such as (?im-sx), which sets PCRE2_CASELESS +and PCRE2_MULTILINE while unsetting PCRE2_DOTALL and PCRE2_EXTENDED, is also permitted. If a letter appears both before and after the hyphen, the option is unset. An empty options setting "(?)" is allowed. Needless to say, it has no effect. @@ -3469,6 +3473,6 @@ Cambridge, England. .rs .sp .nf -Last updated: 11 April 2017 +Last updated: 18 April 2017 Copyright (c) 1997-2017 University of Cambridge. .fi diff --git a/doc/pcre2syntax.3 b/doc/pcre2syntax.3 index 05b129c..7901102 100644 --- a/doc/pcre2syntax.3 +++ b/doc/pcre2syntax.3 @@ -1,4 +1,4 @@ -.TH PCRE2SYNTAX 3 "31 March 2017" "PCRE2 10.30" +.TH PCRE2SYNTAX 3 "18 April 2017" "PCRE2 10.30" .SH NAME PCRE2 - Perl-compatible regular expressions (revised API) .SH "PCRE2 REGULAR EXPRESSION SYNTAX SUMMARY" @@ -409,7 +409,8 @@ but some of them use Unicode properties if PCRE2_UCP is set. You can use (?m) multiline (?s) single line (dotall) (?U) default ungreedy (lazy) - (?x) extended (ignore white space) + (?x) extended: ignore white space except in classes + (?xx) as (?x) but also ignore space and tab in classes (?-...) unset option(s) .sp The following are recognized only at the very start of a pattern or after one @@ -585,6 +586,6 @@ Cambridge, England. .rs .sp .nf -Last updated: 31 March 2017 +Last updated: 18 April 2017 Copyright (c) 1997-2017 University of Cambridge. .fi diff --git a/doc/pcre2test.1 b/doc/pcre2test.1 index 9653241..d177cc4 100644 --- a/doc/pcre2test.1 +++ b/doc/pcre2test.1 @@ -1,4 +1,4 @@ -.TH PCRE2TEST 1 "11 April 2017" "PCRE 10.30" +.TH PCRE2TEST 1 "17 April 2017" "PCRE 10.30" .SH NAME pcre2test - a program for testing Perl-compatible regular expressions. .SH SYNOPSIS @@ -520,11 +520,13 @@ by a previous \fB#pattern\fP command. .rs .sp The following modifiers set options for \fBpcre2_compile()\fP. The most common -ones have single-letter abbreviations. See +ones have single-letter abbreviations, with special handling for /x (to make +it like Perl). If a second x is present, PCRE2_EXTENDED is converted into +PCRE2_EXTENDED_MORE. A third appearance adds PCRE2_EXTENDED as well. See .\" HREF \fBpcre2api\fP .\" -for a description of their effects. +for a description of the effects of these options. .sp allow_empty_class set PCRE2_ALLOW_EMPTY_CLASS alt_bsux set PCRE2_ALT_BSUX @@ -538,6 +540,7 @@ for a description of their effects. dupnames set PCRE2_DUPNAMES endanchored set PCRE2_ENDANCHORED /x extended set PCRE2_EXTENDED + /xx extended_more set PCRE2_EXTENDED_MORE firstline set PCRE2_FIRSTLINE match_unset_backref set PCRE2_MATCH_UNSET_BACKREF /m multiline set PCRE2_MULTILINE @@ -1783,6 +1786,6 @@ Cambridge, England. .rs .sp .nf -Last updated: 11 April 2017 +Last updated: 17 April 2017 Copyright (c) 1997-2017 University of Cambridge. .fi diff --git a/doc/pcre2test.txt b/doc/pcre2test.txt index c311d83..7313c69 100644 --- a/doc/pcre2test.txt +++ b/doc/pcre2test.txt @@ -504,8 +504,11 @@ PATTERN MODIFIERS Setting compilation options The following modifiers set options for pcre2_compile(). The most com- - mon ones have single-letter abbreviations. See pcre2api for a descrip- - tion of their effects. + mon ones have single-letter abbreviations, with special handling for /x + (to make it like Perl). If a second x is present, PCRE2_EXTENDED is + converted into PCRE2_EXTENDED_MORE. A third appearance adds + PCRE2_EXTENDED as well. See pcre2api for a description of the effects + of these options. allow_empty_class set PCRE2_ALLOW_EMPTY_CLASS alt_bsux set PCRE2_ALT_BSUX @@ -519,6 +522,7 @@ PATTERN MODIFIERS dupnames set PCRE2_DUPNAMES endanchored set PCRE2_ENDANCHORED /x extended set PCRE2_EXTENDED + /xx extended_more set PCRE2_EXTENDED_MORE firstline set PCRE2_FIRSTLINE match_unset_backref set PCRE2_MATCH_UNSET_BACKREF /m multiline set PCRE2_MULTILINE @@ -536,15 +540,15 @@ PATTERN MODIFIERS utf set PCRE2_UTF As well as turning on the PCRE2_UTF option, the utf modifier causes all - non-printing characters in output strings to be printed using the - \x{hh...} notation. Otherwise, those less than 0x100 are output in hex - without the curly brackets. Setting utf in 16-bit or 32-bit mode also - causes pattern and subject strings to be translated to UTF-16 or + non-printing characters in output strings to be printed using the + \x{hh...} notation. Otherwise, those less than 0x100 are output in hex + without the curly brackets. Setting utf in 16-bit or 32-bit mode also + causes pattern and subject strings to be translated to UTF-16 or UTF-32, respectively, before being passed to library functions. Setting compilation controls - The following modifiers affect the compilation process or request + The following modifiers affect the compilation process or request information about the pattern: bsr=[anycrlf|unicode] specify \R handling @@ -577,34 +581,34 @@ PATTERN MODIFIERS Newline and \R handling - The bsr modifier specifies what \R in a pattern should match. If it is - set to "anycrlf", \R matches CR, LF, or CRLF only. If it is set to - "unicode", \R matches any Unicode newline sequence. The default is + The bsr modifier specifies what \R in a pattern should match. If it is + set to "anycrlf", \R matches CR, LF, or CRLF only. If it is set to + "unicode", \R matches any Unicode newline sequence. The default is specified when PCRE2 is built, with the default default being Unicode. - The newline modifier specifies which characters are to be interpreted + The newline modifier specifies which characters are to be interpreted as newlines, both in the pattern and in subject lines. The type must be one of CR, LF, CRLF, ANYCRLF, or ANY (in upper or lower case). Information about a pattern - The debug modifier is a shorthand for info,fullbincode, requesting all + The debug modifier is a shorthand for info,fullbincode, requesting all available information. The bincode modifier causes a representation of the compiled code to be - output after compilation. This information does not contain length and + output after compilation. This information does not contain length and offset values, which ensures that the same output is generated for dif- - ferent internal link sizes and different code unit widths. By using - bincode, the same regression tests can be used in different environ- + ferent internal link sizes and different code unit widths. By using + bincode, the same regression tests can be used in different environ- ments. - The fullbincode modifier, by contrast, does include length and offset - values. This is used in a few special tests that run only for specific + The fullbincode modifier, by contrast, does include length and offset + values. This is used in a few special tests that run only for specific code unit widths and link sizes, and is also useful for one-off tests. - The info modifier requests information about the compiled pattern - (whether it is anchored, has a fixed first character, and so on). The - information is obtained from the pcre2_pattern_info() function. Here + The info modifier requests information about the compiled pattern + (whether it is anchored, has a fixed first character, and so on). The + information is obtained from the pcre2_pattern_info() function. Here are some typical examples: re> /(?i)(^a|^b)/m,info @@ -622,118 +626,118 @@ PATTERN MODIFIERS Last code unit = 'c' (caseless) Subject length lower bound = 3 - "Compile options" are those specified by modifiers; "overall options" - have added options that are taken or deduced from the pattern. If both - sets of options are the same, just a single "options" line is output; - if there are no options, the line is omitted. "First code unit" is - where any match must start; if there is more than one they are listed - as "starting code units". "Last code unit" is the last literal code - unit that must be present in any match. This is not necessarily the - last character. These lines are omitted if no starting or ending code + "Compile options" are those specified by modifiers; "overall options" + have added options that are taken or deduced from the pattern. If both + sets of options are the same, just a single "options" line is output; + if there are no options, the line is omitted. "First code unit" is + where any match must start; if there is more than one they are listed + as "starting code units". "Last code unit" is the last literal code + unit that must be present in any match. This is not necessarily the + last character. These lines are omitted if no starting or ending code units are recorded. - The framesize modifier shows the size, in bytes, of the storage frames - used by pcre2_match() for handling backtracking. The size depends on + The framesize modifier shows the size, in bytes, of the storage frames + used by pcre2_match() for handling backtracking. The size depends on the number of capturing parentheses in the pattern. - The callout_info modifier requests information about all the callouts + The callout_info modifier requests information about all the callouts in the pattern. A list of them is output at the end of any other infor- mation that is requested. For each callout, either its number or string is given, followed by the item that follows it in the pattern. Passing a NULL context - Normally, pcre2test passes a context block to pcre2_compile(). If the - null_context modifier is set, however, NULL is passed. This is for - testing that pcre2_compile() behaves correctly in this case (it uses + Normally, pcre2test passes a context block to pcre2_compile(). If the + null_context modifier is set, however, NULL is passed. This is for + testing that pcre2_compile() behaves correctly in this case (it uses default values). Specifying the pattern's length By default, patterns are passed to the compiling functions as zero-ter- - minated strings. When using the POSIX wrapper API, there is no other - option. However, when using PCRE2's native API, patterns can be passed - by length instead of being zero-terminated. The use_length modifier - causes this to happen. Using a length happens automatically (whether - or not use_length is set) when hex is set, because patterns specified + minated strings. When using the POSIX wrapper API, there is no other + option. However, when using PCRE2's native API, patterns can be passed + by length instead of being zero-terminated. The use_length modifier + causes this to happen. Using a length happens automatically (whether + or not use_length is set) when hex is set, because patterns specified in hexadecimal may contain binary zeros. Specifying pattern characters in hexadecimal - The hex modifier specifies that the characters of the pattern, except - for substrings enclosed in single or double quotes, are to be inter- - preted as pairs of hexadecimal digits. This feature is provided as a + The hex modifier specifies that the characters of the pattern, except + for substrings enclosed in single or double quotes, are to be inter- + preted as pairs of hexadecimal digits. This feature is provided as a way of creating patterns that contain binary zeros and other non-print- - ing characters. White space is permitted between pairs of digits. For + ing characters. White space is permitted between pairs of digits. For example, this pattern contains three characters: /ab 32 59/hex - Parts of such a pattern are taken literally if quoted. This pattern - contains nine characters, only two of which are specified in hexadeci- + Parts of such a pattern are taken literally if quoted. This pattern + contains nine characters, only two of which are specified in hexadeci- mal: /ab "literal" 32/hex - Either single or double quotes may be used. There is no way of includ- - ing the delimiter within a substring. The hex and expand modifiers are + Either single or double quotes may be used. There is no way of includ- + ing the delimiter within a substring. The hex and expand modifiers are mutually exclusive. - The POSIX API cannot be used with patterns specified in hexadecimal + The POSIX API cannot be used with patterns specified in hexadecimal because they may contain binary zeros, which conflicts with regcomp()'s - requirement for a zero-terminated string. Such patterns are always + requirement for a zero-terminated string. Such patterns are always passed to pcre2_compile() as a string with a length, not as zero-termi- nated. Specifying wide characters in 16-bit and 32-bit modes In 16-bit and 32-bit modes, all input is automatically treated as UTF-8 - and translated to UTF-16 or UTF-32 when the utf modifier is set. For + and translated to UTF-16 or UTF-32 when the utf modifier is set. For testing the 16-bit and 32-bit libraries in non-UTF mode, the utf8_input - modifier can be used. It is mutually exclusive with utf. Input lines + modifier can be used. It is mutually exclusive with utf. Input lines are interpreted as UTF-8 as a means of specifying wide characters. More details are given in "Input encoding" above. Generating long repetitive patterns - Some tests use long patterns that are very repetitive. Instead of cre- - ating a very long input line for such a pattern, you can use a special - repetition feature, similar to the one described for subject lines - above. If the expand modifier is present on a pattern, parts of the + Some tests use long patterns that are very repetitive. Instead of cre- + ating a very long input line for such a pattern, you can use a special + repetition feature, similar to the one described for subject lines + above. If the expand modifier is present on a pattern, parts of the pattern that have the form \[<characters>]{<count>} are expanded before the pattern is passed to pcre2_compile(). For exam- ple, \[AB]{6000} is expanded to "ABAB..." 6000 times. This construction - cannot be nested. An initial "\[" sequence is recognized only if "]{" - followed by decimal digits and "}" is found later in the pattern. If + cannot be nested. An initial "\[" sequence is recognized only if "]{" + followed by decimal digits and "}" is found later in the pattern. If not, the characters remain in the pattern unaltered. The expand and hex modifiers are mutually exclusive. - If part of an expanded pattern looks like an expansion, but is really + If part of an expanded pattern looks like an expansion, but is really part of the actual pattern, unwanted expansion can be avoided by giving two values in the quantifier. For example, \[AB]{6000,6000} is not rec- ognized as an expansion item. - If the info modifier is set on an expanded pattern, the result of the + If the info modifier is set on an expanded pattern, the result of the expansion is included in the information that is output. JIT compilation - Just-in-time (JIT) compiling is a heavyweight optimization that can - greatly speed up pattern matching. See the pcre2jit documentation for - details. JIT compiling happens, optionally, after a pattern has been - successfully compiled into an internal form. The JIT compiler converts + Just-in-time (JIT) compiling is a heavyweight optimization that can + greatly speed up pattern matching. See the pcre2jit documentation for + details. JIT compiling happens, optionally, after a pattern has been + successfully compiled into an internal form. The JIT compiler converts this to optimized machine code. It needs to know whether the match-time options PCRE2_PARTIAL_HARD and PCRE2_PARTIAL_SOFT are going to be used, - because different code is generated for the different cases. See the - partial modifier in "Subject Modifiers" below for details of how these + because different code is generated for the different cases. See the + partial modifier in "Subject Modifiers" below for details of how these options are specified for each match attempt. - JIT compilation is requested by the /jit pattern modifier, which may + JIT compilation is requested by the /jit pattern modifier, which may optionally be followed by an equals sign and a number in the range 0 to - 7. The three bits that make up the number specify which of the three + 7. The three bits that make up the number specify which of the three JIT operating modes are to be compiled: 1 compile JIT code for non-partial matching @@ -750,31 +754,31 @@ PATTERN MODIFIERS 6 soft and hard partial matching only 7 all three modes - If no number is given, 7 is assumed. The phrase "partial matching" + If no number is given, 7 is assumed. The phrase "partial matching" means a call to pcre2_match() with either the PCRE2_PARTIAL_SOFT or the - PCRE2_PARTIAL_HARD option set. Note that such a call may return a com- + PCRE2_PARTIAL_HARD option set. Note that such a call may return a com- plete match; the options enable the possibility of a partial match, but - do not require it. Note also that if you request JIT compilation only - for partial matching (for example, /jit=2) but do not set the partial - modifier on a subject line, that match will not use JIT code because + do not require it. Note also that if you request JIT compilation only + for partial matching (for example, /jit=2) but do not set the partial + modifier on a subject line, that match will not use JIT code because none was compiled for non-partial matching. - If JIT compilation is successful, the compiled JIT code will automati- - cally be used when an appropriate type of match is run, except when - incompatible run-time options are specified. For more details, see the - pcre2jit documentation. See also the jitstack modifier below for a way + If JIT compilation is successful, the compiled JIT code will automati- + cally be used when an appropriate type of match is run, except when + incompatible run-time options are specified. For more details, see the + pcre2jit documentation. See also the jitstack modifier below for a way of setting the size of the JIT stack. - If the jitfast modifier is specified, matching is done using the JIT - "fast path" interface, pcre2_jit_match(), which skips some of the san- - ity checks that are done by pcre2_match(), and of course does not work - when JIT is not supported. If jitfast is specified without jit, jit=7 + If the jitfast modifier is specified, matching is done using the JIT + "fast path" interface, pcre2_jit_match(), which skips some of the san- + ity checks that are done by pcre2_match(), and of course does not work + when JIT is not supported. If jitfast is specified without jit, jit=7 is assumed. - If the jitverify modifier is specified, information about the compiled - pattern shows whether JIT compilation was or was not successful. If - jitverify is specified without jit, jit=7 is assumed. If JIT compila- - tion is successful when jitverify is set, the text "(JIT)" is added to + If the jitverify modifier is specified, information about the compiled + pattern shows whether JIT compilation was or was not successful. If + jitverify is specified without jit, jit=7 is assumed. If JIT compila- + tion is successful when jitverify is set, the text "(JIT)" is added to the first output line after a match or non match when JIT-compiled code was actually used in the match. @@ -785,19 +789,19 @@ PATTERN MODIFIERS /pattern/locale=fr_FR The given locale is set, pcre2_maketables() is called to build a set of - character tables for the locale, and this is then passed to pcre2_com- - pile() when compiling the regular expression. The same tables are used - when matching the following subject lines. The locale modifier applies + character tables for the locale, and this is then passed to pcre2_com- + pile() when compiling the regular expression. The same tables are used + when matching the following subject lines. The locale modifier applies only to the pattern on which it appears, but can be given in a #pattern - command if a default is needed. Setting a locale and alternate charac- + command if a default is needed. Setting a locale and alternate charac- ter tables are mutually exclusive. Showing pattern memory The memory modifier causes the size in bytes of the memory used to hold - the compiled pattern to be output. This does not include the size of - the pcre2_code block; it is just the actual compiled data. If the pat- - tern is subsequently passed to the JIT compiler, the size of the JIT + the compiled pattern to be output. This does not include the size of + the pcre2_code block; it is just the actual compiled data. If the pat- + tern is subsequently passed to the JIT compiler, the size of the JIT compiled code is also output. Here is an example: re> /a(b)c/jit,memory @@ -807,27 +811,27 @@ PATTERN MODIFIERS Limiting nested parentheses - The parens_nest_limit modifier sets a limit on the depth of nested - parentheses in a pattern. Breaching the limit causes a compilation - error. The default for the library is set when PCRE2 is built, but - pcre2test sets its own default of 220, which is required for running + The parens_nest_limit modifier sets a limit on the depth of nested + parentheses in a pattern. Breaching the limit causes a compilation + error. The default for the library is set when PCRE2 is built, but + pcre2test sets its own default of 220, which is required for running the standard test suite. Limiting the pattern length - The max_pattern_length modifier sets a limit, in code units, to the + The max_pattern_length modifier sets a limit, in code units, to the length of pattern that pcre2_compile() will accept. Breaching the limit - causes a compilation error. The default is the largest number a + causes a compilation error. The default is the largest number a PCRE2_SIZE variable can hold (essentially unlimited). Using the POSIX wrapper API - The /posix and posix_nosub modifiers cause pcre2test to call PCRE2 via - the POSIX wrapper API rather than its native API. When posix_nosub is - used, the POSIX option REG_NOSUB is passed to regcomp(). The POSIX - wrapper supports only the 8-bit library. Note that it does not imply + The /posix and posix_nosub modifiers cause pcre2test to call PCRE2 via + the POSIX wrapper API rather than its native API. When posix_nosub is + used, the POSIX option REG_NOSUB is passed to regcomp(). The POSIX + wrapper supports only the 8-bit library. Note that it does not imply POSIX matching semantics; for more detail see the pcre2posix documenta- - tion. The following pattern modifiers set options for the regcomp() + tion. The following pattern modifiers set options for the regcomp() function: caseless REG_ICASE @@ -837,35 +841,35 @@ PATTERN MODIFIERS ucp REG_UCP ) the POSIX standard utf REG_UTF8 ) - The regerror_buffsize modifier specifies a size for the error buffer - that is passed to regerror() in the event of a compilation error. For + The regerror_buffsize modifier specifies a size for the error buffer + that is passed to regerror() in the event of a compilation error. For example: /abc/posix,regerror_buffsize=20 - This provides a means of testing the behaviour of regerror() when the - buffer is too small for the error message. If this modifier has not + This provides a means of testing the behaviour of regerror() when the + buffer is too small for the error message. If this modifier has not been set, a large buffer is used. - The aftertext and allaftertext subject modifiers work as described - below. All other modifiers are either ignored, with a warning message, + The aftertext and allaftertext subject modifiers work as described + below. All other modifiers are either ignored, with a warning message, or cause an error. Testing the stack guard feature - The stackguard modifier is used to test the use of pcre2_set_com- - pile_recursion_guard(), a function that is provided to enable stack - availability to be checked during compilation (see the pcre2api docu- - mentation for details). If the number specified by the modifier is + The stackguard modifier is used to test the use of pcre2_set_com- + pile_recursion_guard(), a function that is provided to enable stack + availability to be checked during compilation (see the pcre2api docu- + mentation for details). If the number specified by the modifier is greater than zero, pcre2_set_compile_recursion_guard() is called to set - up callback from pcre2_compile() to a local function. The argument it - receives is the current nesting parenthesis depth; if this is greater + up callback from pcre2_compile() to a local function. The argument it + receives is the current nesting parenthesis depth; if this is greater than the value given by the modifier, non-zero is returned, causing the compilation to be aborted. Using alternative character tables - The value specified for the tables modifier must be one of the digits + The value specified for the tables modifier must be one of the digits 0, 1, or 2. It causes a specific set of built-in character tables to be passed to pcre2_compile(). This is used in the PCRE2 tests to check be- haviour with different character tables. The digit specifies the tables @@ -876,15 +880,15 @@ PATTERN MODIFIERS pcre2_chartables.c.dist 2 a set of tables defining ISO 8859 characters - In table 2, some characters whose codes are greater than 128 are iden- - tified as letters, digits, spaces, etc. Setting alternate character + In table 2, some characters whose codes are greater than 128 are iden- + tified as letters, digits, spaces, etc. Setting alternate character tables and a locale are mutually exclusive. Setting certain match controls The following modifiers are really subject modifiers, and are described - below. However, they may be included in a pattern's modifier list, in - which case they are applied to every subject line that is processed + below. However, they may be included in a pattern's modifier list, in + which case they are applied to every subject line that is processed with that pattern. They may not appear in #pattern commands. These mod- ifiers do not affect the compilation process. @@ -901,24 +905,24 @@ PATTERN MODIFIERS substitute_unknown_unset use PCRE2_SUBSTITUTE_UNKNOWN_UNSET substitute_unset_empty use PCRE2_SUBSTITUTE_UNSET_EMPTY - These modifiers may not appear in a #pattern command. If you want them + These modifiers may not appear in a #pattern command. If you want them as defaults, set them in a #subject command. Saving a compiled pattern - When a pattern with the push modifier is successfully compiled, it is - pushed onto a stack of compiled patterns, and pcre2test expects the - next line to contain a new pattern (or a command) instead of a subject + When a pattern with the push modifier is successfully compiled, it is + pushed onto a stack of compiled patterns, and pcre2test expects the + next line to contain a new pattern (or a command) instead of a subject line. This facility is used when saving compiled patterns to a file, as - described in the section entitled "Saving and restoring compiled pat- - terns" below. If pushcopy is used instead of push, a copy of the com- - piled pattern is stacked, leaving the original as current, ready to - match the following input lines. This provides a way of testing the - pcre2_code_copy() function. The push and pushcopy modifiers are - incompatible with compilation modifiers such as global that act at - match time. Any that are specified are ignored (for the stacked copy), + described in the section entitled "Saving and restoring compiled pat- + terns" below. If pushcopy is used instead of push, a copy of the com- + piled pattern is stacked, leaving the original as current, ready to + match the following input lines. This provides a way of testing the + pcre2_code_copy() function. The push and pushcopy modifiers are + incompatible with compilation modifiers such as global that act at + match time. Any that are specified are ignored (for the stacked copy), with a warning message, except for replace, which causes an error. Note - that jitverify, which is allowed, does not carry through to any subse- + that jitverify, which is allowed, does not carry through to any subse- quent matching that uses a stacked pattern. @@ -929,7 +933,7 @@ SUBJECT MODIFIERS Setting match options - The following modifiers set options for pcre2_match() or + The following modifiers set options for pcre2_match() or pcre2_dfa_match(). See pcreapi for a description of their effects. anchored set PCRE2_ANCHORED @@ -945,20 +949,20 @@ SUBJECT MODIFIERS partial_hard (or ph) set PCRE2_PARTIAL_HARD partial_soft (or ps) set PCRE2_PARTIAL_SOFT - The partial matching modifiers are provided with abbreviations because + The partial matching modifiers are provided with abbreviations because they appear frequently in tests. - If the posix modifier was present on the pattern, causing the POSIX + If the posix modifier was present on the pattern, causing the POSIX wrapper API to be used, the only option-setting modifiers that have any - effect are notbol, notempty, and noteol, causing REG_NOTBOL, - REG_NOTEMPTY, and REG_NOTEOL, respectively, to be passed to regexec(). + effect are notbol, notempty, and noteol, causing REG_NOTBOL, + REG_NOTEMPTY, and REG_NOTEOL, respectively, to be passed to regexec(). The other modifiers are ignored, with a warning message. Setting match controls - The following modifiers affect the matching process or request addi- - tional information. Some of them may also be specified on a pattern - line (see above), in which case they apply to every subject line that + The following modifiers affect the matching process or request addi- + tional information. Some of them may also be specified on a pattern + line (see above), in which case they apply to every subject line that is matched against that pattern. aftertext show text after match @@ -998,29 +1002,29 @@ SUBJECT MODIFIERS zero_terminate pass the subject as zero-terminated The effects of these modifiers are described in the following sections. - When matching via the POSIX wrapper API, the aftertext, allaftertext, - and ovector subject modifiers work as described below. All other modi- + When matching via the POSIX wrapper API, the aftertext, allaftertext, + and ovector subject modifiers work as described below. All other modi- fiers are either ignored, with a warning message, or cause an error. Showing more text - The aftertext modifier requests that as well as outputting the part of + The aftertext modifier requests that as well as outputting the part of the subject string that matched the entire pattern, pcre2test should in addition output the remainder of the subject string. This is useful for tests where the subject contains multiple copies of the same substring. - The allaftertext modifier requests the same action for captured sub- + The allaftertext modifier requests the same action for captured sub- strings as well as the main matched substring. In each case the remain- der is output on the following line with a plus character following the capture number. - The allusedtext modifier requests that all the text that was consulted - during a successful pattern match by the interpreter should be shown. - This feature is not supported for JIT matching, and if requested with - JIT it is ignored (with a warning message). Setting this modifier + The allusedtext modifier requests that all the text that was consulted + during a successful pattern match by the interpreter should be shown. + This feature is not supported for JIT matching, and if requested with + JIT it is ignored (with a warning message). Setting this modifier affects the output if there is a lookbehind at the start of a match, or - a lookahead at the end, or if \K is used in the pattern. Characters - that precede or follow the start and end of the actual match are indi- - cated in the output by '<' or '>' characters underneath them. Here is + a lookahead at the end, or if \K is used in the pattern. Characters + that precede or follow the start and end of the actual match are indi- + cated in the output by '<' or '>' characters underneath them. Here is an example: re> /(?<=pqr)abc(?=xyz)/ @@ -1028,16 +1032,16 @@ SUBJECT MODIFIERS 0: pqrabcxyz <<< >>> - This shows that the matched string is "abc", with the preceding and - following strings "pqr" and "xyz" having been consulted during the + This shows that the matched string is "abc", with the preceding and + following strings "pqr" and "xyz" having been consulted during the match (when processing the assertions). - The startchar modifier requests that the starting character for the - match be indicated, if it is different to the start of the matched + The startchar modifier requests that the starting character for the + match be indicated, if it is different to the start of the matched string. The only time when this occurs is when \K has been processed as part of the match. In this situation, the output for the matched string - is displayed from the starting character instead of from the match - point, with circumflex characters under the earlier characters. For + is displayed from the starting character instead of from the match + point, with circumflex characters under the earlier characters. For example: re> /abc\Kxyz/ @@ -1045,7 +1049,7 @@ SUBJECT MODIFIERS 0: abcxyz ^^^ - Unlike allusedtext, the startchar modifier can be used with JIT. How- + Unlike allusedtext, the startchar modifier can be used with JIT. How- ever, these two modifiers are mutually exclusive. Showing the value of all capture groups @@ -1053,98 +1057,98 @@ SUBJECT MODIFIERS The allcaptures modifier requests that the values of all potential cap- tured parentheses be output after a match. By default, only those up to the highest one actually used in the match are output (corresponding to - the return code from pcre2_match()). Groups that did not take part in - the match are output as "<unset>". This modifier is not relevant for - DFA matching (which does no capturing); it is ignored, with a warning + the return code from pcre2_match()). Groups that did not take part in + the match are output as "<unset>". This modifier is not relevant for + DFA matching (which does no capturing); it is ignored, with a warning message, if present. Testing callouts - A callout function is supplied when pcre2test calls the library match- - ing functions, unless callout_none is specified. If callout_capture is - set, the current captured groups are output when a callout occurs. The + A callout function is supplied when pcre2test calls the library match- + ing functions, unless callout_none is specified. If callout_capture is + set, the current captured groups are output when a callout occurs. The default return from the callout function is zero, which allows matching to continue. - The callout_fail modifier can be given one or two numbers. If there is - only one number, 1 is returned instead of 0 (causing matching to back- - track) when a callout of that number is reached. If two numbers - (<n>:<m>) are given, 1 is returned when callout <n> is reached and - there have been at least <m> callouts. The callout_error modifier is - similar, except that PCRE2_ERROR_CALLOUT is returned, causing the - entire matching process to be aborted. If both these modifiers are set + The callout_fail modifier can be given one or two numbers. If there is + only one number, 1 is returned instead of 0 (causing matching to back- + track) when a callout of that number is reached. If two numbers + (<n>:<m>) are given, 1 is returned when callout <n> is reached and + there have been at least <m> callouts. The callout_error modifier is + similar, except that PCRE2_ERROR_CALLOUT is returned, causing the + entire matching process to be aborted. If both these modifiers are set for the same callout number, callout_error takes precedence. - Note that callouts with string arguments are always given the number + Note that callouts with string arguments are always given the number zero. See "Callouts" below for a description of the output when a call- out it taken. - The callout_data modifier can be given an unsigned or a negative num- - ber. This is set as the "user data" that is passed to the matching - function, and passed back when the callout function is invoked. Any - value other than zero is used as a return from pcre2test's callout + The callout_data modifier can be given an unsigned or a negative num- + ber. This is set as the "user data" that is passed to the matching + function, and passed back when the callout function is invoked. Any + value other than zero is used as a return from pcre2test's callout function. Finding all matches in a string Searching for all possible matches within a subject can be requested by - the global or altglobal modifier. After finding a match, the matching - function is called again to search the remainder of the subject. The - difference between global and altglobal is that the former uses the - start_offset argument to pcre2_match() or pcre2_dfa_match() to start - searching at a new point within the entire string (which is what Perl + the global or altglobal modifier. After finding a match, the matching + function is called again to search the remainder of the subject. The + difference between global and altglobal is that the former uses the + start_offset argument to pcre2_match() or pcre2_dfa_match() to start + searching at a new point within the entire string (which is what Perl does), whereas the latter passes over a shortened subject. This makes a difference to the matching process if the pattern begins with a lookbe- hind assertion (including \b or \B). - If an empty string is matched, the next match is done with the + If an empty string is matched, the next match is done with the PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED flags set, in order to search for another, non-empty, match at the same point in the subject. If this - match fails, the start offset is advanced, and the normal match is - retried. This imitates the way Perl handles such cases when using the - /g modifier or the split() function. Normally, the start offset is - advanced by one character, but if the newline convention recognizes - CRLF as a newline, and the current character is CR followed by LF, an + match fails, the start offset is advanced, and the normal match is + retried. This imitates the way Perl handles such cases when using the + /g modifier or the split() function. Normally, the start offset is + advanced by one character, but if the newline convention recognizes + CRLF as a newline, and the current character is CR followed by LF, an advance of two characters occurs. Testing substring extraction functions - The copy and get modifiers can be used to test the pcre2_sub- + The copy and get modifiers can be used to test the pcre2_sub- string_copy_xxx() and pcre2_substring_get_xxx() functions. They can be - given more than once, and each can specify a group name or number, for + given more than once, and each can specify a group name or number, for example: abcd\=copy=1,copy=3,get=G1 - If the #subject command is used to set default copy and/or get lists, - these can be unset by specifying a negative number to cancel all num- + If the #subject command is used to set default copy and/or get lists, + these can be unset by specifying a negative number to cancel all num- bered groups and an empty name to cancel all named groups. - The getall modifier tests pcre2_substring_list_get(), which extracts + The getall modifier tests pcre2_substring_list_get(), which extracts all captured substrings. - If the subject line is successfully matched, the substrings extracted - by the convenience functions are output with C, G, or L after the - string number instead of a colon. This is in addition to the normal - full list. The string length (that is, the return from the extraction + If the subject line is successfully matched, the substrings extracted + by the convenience functions are output with C, G, or L after the + string number instead of a colon. This is in addition to the normal + full list. The string length (that is, the return from the extraction function) is given in parentheses after each substring, followed by the name when the extraction was by name. Testing the substitution function - If the replace modifier is set, the pcre2_substitute() function is - called instead of one of the matching functions. Note that replacement - strings cannot contain commas, because a comma signifies the end of a + If the replace modifier is set, the pcre2_substitute() function is + called instead of one of the matching functions. Note that replacement + strings cannot contain commas, because a comma signifies the end of a modifier. This is not thought to be an issue in a test program. - Unlike subject strings, pcre2test does not process replacement strings - for escape sequences. In UTF mode, a replacement string is checked to - see if it is a valid UTF-8 string. If so, it is correctly converted to - a UTF string of the appropriate code unit width. If it is not a valid - UTF-8 string, the individual code units are copied directly. This pro- + Unlike subject strings, pcre2test does not process replacement strings + for escape sequences. In UTF mode, a replacement string is checked to + see if it is a valid UTF-8 string. If so, it is correctly converted to + a UTF string of the appropriate code unit width. If it is not a valid + UTF-8 string, the individual code units are copied directly. This pro- vides a means of passing an invalid UTF-8 string for testing purposes. - The following modifiers set options (in additional to the normal match + The following modifiers set options (in additional to the normal match options) for pcre2_substitute(): global PCRE2_SUBSTITUTE_GLOBAL @@ -1154,8 +1158,8 @@ SUBJECT MODIFIERS substitute_unset_empty PCRE2_SUBSTITUTE_UNSET_EMPTY - After a successful substitution, the modified string is output, pre- - ceded by the number of replacements. This may be zero if there were no + After a successful substitution, the modified string is output, pre- + ceded by the number of replacements. This may be zero if there were no matches. Here is a simple example of a substitution test: /abc/replace=xxx @@ -1164,12 +1168,12 @@ SUBJECT MODIFIERS =abc=abc=\=global 2: =xxx=xxx= - Subject and replacement strings should be kept relatively short (fewer - than 256 characters) for substitution tests, as fixed-size buffers are - used. To make it easy to test for buffer overflow, if the replacement - string starts with a number in square brackets, that number is passed - to pcre2_substitute() as the size of the output buffer, with the - replacement string starting at the next character. Here is an example + Subject and replacement strings should be kept relatively short (fewer + than 256 characters) for substitution tests, as fixed-size buffers are + used. To make it easy to test for buffer overflow, if the replacement + string starts with a number in square brackets, that number is passed + to pcre2_substitute() as the size of the output buffer, with the + replacement string starting at the next character. Here is an example that tests the edge case: /abc/ @@ -1178,11 +1182,11 @@ SUBJECT MODIFIERS 123abc123\=replace=[9]XYZ Failed: error -47: no more memory - The default action of pcre2_substitute() is to return - PCRE2_ERROR_NOMEMORY when the output buffer is too small. However, if - the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set (by using the sub- - stitute_overflow_length modifier), pcre2_substitute() continues to go - through the motions of matching and substituting, in order to compute + The default action of pcre2_substitute() is to return + PCRE2_ERROR_NOMEMORY when the output buffer is too small. However, if + the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set (by using the sub- + stitute_overflow_length modifier), pcre2_substitute() continues to go + through the motions of matching and substituting, in order to compute the size of buffer that is required. When this happens, pcre2test shows the required buffer length (which includes space for the trailing zero) as part of the error message. For example: @@ -1192,151 +1196,151 @@ SUBJECT MODIFIERS Failed: error -47: no more memory: 10 code units are needed A replacement string is ignored with POSIX and DFA matching. Specifying - partial matching provokes an error return ("bad option value") from + partial matching provokes an error return ("bad option value") from pcre2_substitute(). Setting the JIT stack size - The jitstack modifier provides a way of setting the maximum stack size - that is used by the just-in-time optimization code. It is ignored if + The jitstack modifier provides a way of setting the maximum stack size + that is used by the just-in-time optimization code. It is ignored if JIT optimization is not being used. The value is a number of kilobytes. Providing a stack that is larger than the default 32K is necessary only for very complicated patterns. Setting heap, match, and depth limits - The heap_limit, match_limit, and depth_limit modifiers set the appro- - priate limits in the match context. These values are ignored when the + The heap_limit, match_limit, and depth_limit modifiers set the appro- + priate limits in the match context. These values are ignored when the find_limits modifier is specified. Finding minimum limits - If the find_limits modifier is present on a subject line, pcre2test - calls the relevant matching function several times, setting different - values in the match context via pcre2_set_heap_limit(), - pcre2_set_match_limit(), or pcre2_set_depth_limit() until it finds the - minimum values for each parameter that allows the match to complete + If the find_limits modifier is present on a subject line, pcre2test + calls the relevant matching function several times, setting different + values in the match context via pcre2_set_heap_limit(), + pcre2_set_match_limit(), or pcre2_set_depth_limit() until it finds the + minimum values for each parameter that allows the match to complete without error. If JIT is being used, only the match limit is relevant. If DFA matching is being used, only the depth limit is relevant. - The match_limit number is a measure of the amount of backtracking that - takes place, and learning the minimum value can be instructive. For - most simple matches, the number is quite small, but for patterns with - very large numbers of matching possibilities, it can become large very + The match_limit number is a measure of the amount of backtracking that + takes place, and learning the minimum value can be instructive. For + most simple matches, the number is quite small, but for patterns with + very large numbers of matching possibilities, it can become large very quickly with increasing length of subject string. - For non-DFA matching, the minimum depth_limit number is a measure of + For non-DFA matching, the minimum depth_limit number is a measure of how much nested backtracking happens (that is, how deeply the pattern's - tree is searched). In the case of DFA matching, depth_limit controls - the depth of recursive calls of the internal function that is used for + tree is searched). In the case of DFA matching, depth_limit controls + the depth of recursive calls of the internal function that is used for handling pattern recursion, lookaround assertions, and atomic groups. Showing MARK names The mark modifier causes the names from backtracking control verbs that - are returned from calls to pcre2_match() to be displayed. If a mark is - returned for a match, non-match, or partial match, pcre2test shows it. - For a match, it is on a line by itself, tagged with "MK:". Otherwise, + are returned from calls to pcre2_match() to be displayed. If a mark is + returned for a match, non-match, or partial match, pcre2test shows it. + For a match, it is on a line by itself, tagged with "MK:". Otherwise, it is added to the non-match message. Showing memory usage - The memory modifier causes pcre2test to log the sizes of all heap mem- - ory allocation and freeing calls that occur during a call to - pcre2_match(). These occur only when a match requires a bigger vector - than the default for remembering backtracking points. In many cases - there will be no heap memory used and therefore no additional output. - No heap memory is allocated during matching with pcre2_dfa_match or - with JIT, so in those cases the memory modifier never has any effect. + The memory modifier causes pcre2test to log the sizes of all heap mem- + ory allocation and freeing calls that occur during a call to + pcre2_match(). These occur only when a match requires a bigger vector + than the default for remembering backtracking points. In many cases + there will be no heap memory used and therefore no additional output. + No heap memory is allocated during matching with pcre2_dfa_match or + with JIT, so in those cases the memory modifier never has any effect. For this modifier to work, the null_context modifier must not be set on - both the pattern and the subject, though it can be set on one or the + both the pattern and the subject, though it can be set on one or the other. Setting a starting offset - The offset modifier sets an offset in the subject string at which + The offset modifier sets an offset in the subject string at which matching starts. Its value is a number of code units, not characters. Setting an offset limit - The offset_limit modifier sets a limit for unanchored matches. If a + The offset_limit modifier sets a limit for unanchored matches. If a match cannot be found starting at or before this offset in the subject, a "no match" return is given. The data value is a number of code units, - not characters. When this modifier is used, the use_offset_limit modi- + not characters. When this modifier is used, the use_offset_limit modi- fier must have been set for the pattern; if not, an error is generated. Setting the size of the output vector - The ovector modifier applies only to the subject line in which it - appears, though of course it can also be used to set a default in a - #subject command. It specifies the number of pairs of offsets that are + The ovector modifier applies only to the subject line in which it + appears, though of course it can also be used to set a default in a + #subject command. It specifies the number of pairs of offsets that are available for storing matching information. The default is 15. - A value of zero is useful when testing the POSIX API because it causes + A value of zero is useful when testing the POSIX API because it causes regexec() to be called with a NULL capture vector. When not testing the - POSIX API, a value of zero is used to cause pcre2_match_data_cre- - ate_from_pattern() to be called, in order to create a match block of + POSIX API, a value of zero is used to cause pcre2_match_data_cre- + ate_from_pattern() to be called, in order to create a match block of exactly the right size for the pattern. (It is not possible to create a - match block with a zero-length ovector; there is always at least one + match block with a zero-length ovector; there is always at least one pair of offsets.) Passing the subject as zero-terminated By default, the subject string is passed to a native API matching func- tion with its correct length. In order to test the facility for passing - a zero-terminated string, the zero_terminate modifier is provided. It + a zero-terminated string, the zero_terminate modifier is provided. It causes the length to be passed as PCRE2_ZERO_TERMINATED. (When matching - via the POSIX interface, this modifier has no effect, as there is no + via the POSIX interface, this modifier has no effect, as there is no facility for passing a length.) - When testing pcre2_substitute(), this modifier also has the effect of + When testing pcre2_substitute(), this modifier also has the effect of passing the replacement string as zero-terminated. Passing a NULL context - Normally, pcre2test passes a context block to pcre2_match(), + Normally, pcre2test passes a context block to pcre2_match(), pcre2_dfa_match() or pcre2_jit_match(). If the null_context modifier is - set, however, NULL is passed. This is for testing that the matching + set, however, NULL is passed. This is for testing that the matching functions behave correctly in this case (they use default values). This - modifier cannot be used with the find_limits modifier or when testing + modifier cannot be used with the find_limits modifier or when testing the substitution function. THE ALTERNATIVE MATCHING FUNCTION - By default, pcre2test uses the standard PCRE2 matching function, + By default, pcre2test uses the standard PCRE2 matching function, pcre2_match() to match each subject line. PCRE2 also supports an alter- - native matching function, pcre2_dfa_match(), which operates in a dif- - ferent way, and has some restrictions. The differences between the two + native matching function, pcre2_dfa_match(), which operates in a dif- + ferent way, and has some restrictions. The differences between the two functions are described in the pcre2matching documentation. - If the dfa modifier is set, the alternative matching function is used. - This function finds all possible matches at a given point in the sub- - ject. If, however, the dfa_shortest modifier is set, processing stops - after the first match is found. This is always the shortest possible + If the dfa modifier is set, the alternative matching function is used. + This function finds all possible matches at a given point in the sub- + ject. If, however, the dfa_shortest modifier is set, processing stops + after the first match is found. This is always the shortest possible match. DEFAULT OUTPUT FROM pcre2test - This section describes the output when the normal matching function, + This section describes the output when the normal matching function, pcre2_match(), is being used. - When a match succeeds, pcre2test outputs the list of captured sub- - strings, starting with number 0 for the string that matched the whole - pattern. Otherwise, it outputs "No match" when the return is - PCRE2_ERROR_NOMATCH, or "Partial match:" followed by the partially - matching substring when the return is PCRE2_ERROR_PARTIAL. (Note that - this is the entire substring that was inspected during the partial - match; it may include characters before the actual match start if a + When a match succeeds, pcre2test outputs the list of captured sub- + strings, starting with number 0 for the string that matched the whole + pattern. Otherwise, it outputs "No match" when the return is + PCRE2_ERROR_NOMATCH, or "Partial match:" followed by the partially + matching substring when the return is PCRE2_ERROR_PARTIAL. (Note that + this is the entire substring that was inspected during the partial + match; it may include characters before the actual match start if a lookbehind assertion, \K, \b, or \B was involved.) For any other return, pcre2test outputs the PCRE2 negative error number - and a short descriptive phrase. If the error is a failed UTF string - check, the code unit offset of the start of the failing character is + and a short descriptive phrase. If the error is a failed UTF string + check, the code unit offset of the start of the failing character is also output. Here is an example of an interactive pcre2test run. $ pcre2test @@ -1352,8 +1356,8 @@ DEFAULT OUTPUT FROM pcre2test Unset capturing substrings that are not followed by one that is set are not shown by pcre2test unless the allcaptures modifier is specified. In the following example, there are two capturing substrings, but when the - first data line is matched, the second, unset substring is not shown. - An "internal" unset substring is shown as "<unset>", as for the second + first data line is matched, the second, unset substring is not shown. + An "internal" unset substring is shown as "<unset>", as for the second data line. re> /(a)|(b)/ @@ -1365,11 +1369,11 @@ DEFAULT OUTPUT FROM pcre2test 1: <unset> 2: b - If the strings contain any non-printing characters, they are output as - \xhh escapes if the value is less than 256 and UTF mode is not set. + If the strings contain any non-printing characters, they are output as + \xhh escapes if the value is less than 256 and UTF mode is not set. Otherwise they are output as \x{hh...} escapes. See below for the defi- - nition of non-printing characters. If the aftertext modifier is set, - the output for substring 0 is followed by the the rest of the subject + nition of non-printing characters. If the aftertext modifier is set, + the output for substring 0 is followed by the the rest of the subject string, identified by "0+" like this: re> /cat/aftertext @@ -1377,7 +1381,7 @@ DEFAULT OUTPUT FROM pcre2test 0: cat 0+ aract - If global matching is requested, the results of successive matching + If global matching is requested, the results of successive matching attempts are output in sequence, like this: re> /\Bi(\w\w)/g @@ -1389,8 +1393,8 @@ DEFAULT OUTPUT FROM pcre2test 0: ipp 1: pp - "No match" is output only if the first match attempt fails. Here is an - example of a failure message (the offset 4 that is specified by the + "No match" is output only if the first match attempt fails. Here is an + example of a failure message (the offset 4 that is specified by the offset modifier is past the end of the subject string): re> /xyz/ @@ -1398,7 +1402,7 @@ DEFAULT OUTPUT FROM pcre2test Error -24 (bad offset value) Note that whereas patterns can be continued over several lines (a plain - ">" prompt is used for continuations), subject lines may not. However + ">" prompt is used for continuations), subject lines may not. However newlines can be included in a subject by means of the \n escape (or \r, \r\n, etc., depending on the newline sequence setting). @@ -1406,7 +1410,7 @@ DEFAULT OUTPUT FROM pcre2test OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION When the alternative matching function, pcre2_dfa_match(), is used, the - output consists of a list of all the matches that start at the first + output consists of a list of all the matches that start at the first point in the subject where there is at least one match. For example: re> /(tang|tangerine|tan)/ @@ -1415,11 +1419,11 @@ OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION 1: tang 2: tan - Using the normal matching function on this data finds only "tang". The - longest matching string is always given first (and numbered zero). - After a PCRE2_ERROR_PARTIAL return, the output is "Partial match:", - followed by the partially matching substring. Note that this is the - entire substring that was inspected during the partial match; it may + Using the normal matching function on this data finds only "tang". The + longest matching string is always given first (and numbered zero). + After a PCRE2_ERROR_PARTIAL return, the output is "Partial match:", + followed by the partially matching substring. Note that this is the + entire substring that was inspected during the partial match; it may include characters before the actual match start if a lookbehind asser- tion, \b, or \B was involved. (\K is not supported for DFA matching.) @@ -1435,16 +1439,16 @@ OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION 1: tan 0: tan - The alternative matching function does not support substring capture, - so the modifiers that are concerned with captured substrings are not + The alternative matching function does not support substring capture, + so the modifiers that are concerned with captured substrings are not relevant. RESTARTING AFTER A PARTIAL MATCH - When the alternative matching function has given the PCRE2_ERROR_PAR- + When the alternative matching function has given the PCRE2_ERROR_PAR- TIAL return, indicating that the subject partially matched the pattern, - you can restart the match with additional subject data by means of the + you can restart the match with additional subject data by means of the dfa_restart modifier. For example: re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/ @@ -1453,45 +1457,45 @@ RESTARTING AFTER A PARTIAL MATCH data> n05\=dfa,dfa_restart 0: n05 - For further information about partial matching, see the pcre2partial + For further information about partial matching, see the pcre2partial documentation. CALLOUTS If the pattern contains any callout requests, pcre2test's callout func- - tion is called during matching unless callout_none is specified. This + tion is called during matching unless callout_none is specified. This works with both matching functions. - The callout function in pcre2test returns zero (carry on matching) by - default, but you can use a callout_fail modifier in a subject line (as + The callout function in pcre2test returns zero (carry on matching) by + default, but you can use a callout_fail modifier in a subject line (as described above) to change this and other parameters of the callout. Inserting callouts can be helpful when using pcre2test to check compli- - cated regular expressions. For further information about callouts, see + cated regular expressions. For further information about callouts, see the pcre2callout documentation. - The output for callouts with numerical arguments and those with string + The output for callouts with numerical arguments and those with string arguments is slightly different. Callouts with numerical arguments By default, the callout function displays the callout number, the start - and current positions in the subject text at the callout time, and the + and current positions in the subject text at the callout time, and the next pattern item to be tested. For example: --->pqrabcdef 0 ^ ^ \d - This output indicates that callout number 0 occurred for a match - attempt starting at the fourth character of the subject string, when - the pointer was at the seventh character, and when the next pattern - item was \d. Just one circumflex is output if the start and current - positions are the same, or if the current position precedes the start + This output indicates that callout number 0 occurred for a match + attempt starting at the fourth character of the subject string, when + the pointer was at the seventh character, and when the next pattern + item was \d. Just one circumflex is output if the start and current + positions are the same, or if the current position precedes the start position, which can happen if the callout is in a lookbehind assertion. Callouts numbered 255 are assumed to be automatic callouts, inserted as - a result of the /auto_callout pattern modifier. In this case, instead + a result of the /auto_callout pattern modifier. In this case, instead of showing the callout number, the offset in the pattern, preceded by a plus, is output. For example: @@ -1505,7 +1509,7 @@ CALLOUTS 0: E* If a pattern contains (*MARK) items, an additional line is output when- - ever a change of latest mark is passed to the callout function. For + ever a change of latest mark is passed to the callout function. For example: re> /a(*MARK:X)bc/auto_callout @@ -1519,17 +1523,17 @@ CALLOUTS +12 ^ ^ 0: abc - The mark changes between matching "a" and "b", but stays the same for - the rest of the match, so nothing more is output. If, as a result of - backtracking, the mark reverts to being unset, the text "<unset>" is + The mark changes between matching "a" and "b", but stays the same for + the rest of the match, so nothing more is output. If, as a result of + backtracking, the mark reverts to being unset, the text "<unset>" is output. Callouts with string arguments The output for a callout with a string argument is similar, except that - instead of outputting a callout number before the position indicators, - the callout string and its offset in the pattern string are output - before the reflection of the subject string, and the subject string is + instead of outputting a callout number before the position indicators, + the callout string and its offset in the pattern string are output + before the reflection of the subject string, and the subject string is reflected for each callout. For example: re> /^ab(?C'first')cd(?C"second")ef/ @@ -1546,43 +1550,43 @@ CALLOUTS NON-PRINTING CHARACTERS When pcre2test is outputting text in the compiled version of a pattern, - bytes other than 32-126 are always treated as non-printing characters + bytes other than 32-126 are always treated as non-printing characters and are therefore shown as hex escapes. - When pcre2test is outputting text that is a matched part of a subject - string, it behaves in the same way, unless a different locale has been - set for the pattern (using the locale modifier). In this case, the - isprint() function is used to distinguish printing and non-printing + When pcre2test is outputting text that is a matched part of a subject + string, it behaves in the same way, unless a different locale has been + set for the pattern (using the locale modifier). In this case, the + isprint() function is used to distinguish printing and non-printing characters. SAVING AND RESTORING COMPILED PATTERNS - It is possible to save compiled patterns on disc or elsewhere, and + It is possible to save compiled patterns on disc or elsewhere, and reload them later, subject to a number of restrictions. JIT data cannot - be saved. The host on which the patterns are reloaded must be running + be saved. The host on which the patterns are reloaded must be running the same version of PCRE2, with the same code unit width, and must also - have the same endianness, pointer width and PCRE2_SIZE type. Before - compiled patterns can be saved they must be serialized, that is, con- - verted to a stream of bytes. A single byte stream may contain any num- - ber of compiled patterns, but they must all use the same character + have the same endianness, pointer width and PCRE2_SIZE type. Before + compiled patterns can be saved they must be serialized, that is, con- + verted to a stream of bytes. A single byte stream may contain any num- + ber of compiled patterns, but they must all use the same character tables. A single copy of the tables is included in the byte stream (its size is 1088 bytes). - The functions whose names begin with pcre2_serialize_ are used for - serializing and de-serializing. They are described in the pcre2serial- + The functions whose names begin with pcre2_serialize_ are used for + serializing and de-serializing. They are described in the pcre2serial- ize documentation. In this section we describe the features of pcre2test that can be used to test these functions. - When a pattern with push modifier is successfully compiled, it is - pushed onto a stack of compiled patterns, and pcre2test expects the - next line to contain a new pattern (or command) instead of a subject - line. By contrast, the pushcopy modifier causes a copy of the compiled - pattern to be stacked, leaving the original available for immediate - matching. By using push and/or pushcopy, a number of patterns can be + When a pattern with push modifier is successfully compiled, it is + pushed onto a stack of compiled patterns, and pcre2test expects the + next line to contain a new pattern (or command) instead of a subject + line. By contrast, the pushcopy modifier causes a copy of the compiled + pattern to be stacked, leaving the original available for immediate + matching. By using push and/or pushcopy, a number of patterns can be compiled and retained. These modifiers are incompatible with posix, and - control modifiers that act at match time are ignored (with a message) - for the stacked patterns. The jitverify modifier applies only at com- + control modifiers that act at match time are ignored (with a message) + for the stacked patterns. The jitverify modifier applies only at com- pile time. The command @@ -1590,21 +1594,21 @@ SAVING AND RESTORING COMPILED PATTERNS #save <filename> causes all the stacked patterns to be serialized and the result written - to the named file. Afterwards, all the stacked patterns are freed. The + to the named file. Afterwards, all the stacked patterns are freed. The command #load <filename> - reads the data in the file, and then arranges for it to be de-serial- - ized, with the resulting compiled patterns added to the pattern stack. - The pattern on the top of the stack can be retrieved by the #pop com- - mand, which must be followed by lines of subjects that are to be - matched with the pattern, terminated as usual by an empty line or end - of file. This command may be followed by a modifier list containing - only control modifiers that act after a pattern has been compiled. In + reads the data in the file, and then arranges for it to be de-serial- + ized, with the resulting compiled patterns added to the pattern stack. + The pattern on the top of the stack can be retrieved by the #pop com- + mand, which must be followed by lines of subjects that are to be + matched with the pattern, terminated as usual by an empty line or end + of file. This command may be followed by a modifier list containing + only control modifiers that act after a pattern has been compiled. In particular, hex, posix, posix_nosub, push, and pushcopy are not - allowed, nor are any option-setting modifiers. The JIT modifiers are, - however permitted. Here is an example that saves and reloads two pat- + allowed, nor are any option-setting modifiers. The JIT modifiers are, + however permitted. Here is an example that saves and reloads two pat- terns. /abc/push @@ -1617,10 +1621,10 @@ SAVING AND RESTORING COMPILED PATTERNS #pop jit,bincode abc - If jitverify is used with #pop, it does not automatically imply jit, + If jitverify is used with #pop, it does not automatically imply jit, which is different behaviour from when it is used on a pattern. - The #popcopy command is analagous to the pushcopy modifier in that it + The #popcopy command is analagous to the pushcopy modifier in that it makes current a copy of the topmost stack pattern, leaving the original still on the stack. @@ -1640,5 +1644,5 @@ AUTHOR REVISION - Last updated: 11 April 2017 + Last updated: 17 April 2017 Copyright (c) 1997-2017 University of Cambridge. diff --git a/src/pcre2.h b/src/pcre2.h index e15ede4..21f610d 100644 --- a/src/pcre2.h +++ b/src/pcre2.h @@ -137,6 +137,7 @@ D is inspected during pcre2_dfa_match() execution #define PCRE2_ALT_CIRCUMFLEX 0x00200000u /* J M D */ #define PCRE2_ALT_VERBNAMES 0x00400000u /* C */ #define PCRE2_USE_OFFSET_LIMIT 0x00800000u /* J M D */ +#define PCRE2_EXTENDED_MORE 0x01000000u /* C */ /* These are for pcre2_jit_compile(). */ diff --git a/src/pcre2.h.generic b/src/pcre2.h.generic index e699b8a..21f610d 100644 --- a/src/pcre2.h.generic +++ b/src/pcre2.h.generic @@ -137,6 +137,7 @@ D is inspected during pcre2_dfa_match() execution #define PCRE2_ALT_CIRCUMFLEX 0x00200000u /* J M D */ #define PCRE2_ALT_VERBNAMES 0x00400000u /* C */ #define PCRE2_USE_OFFSET_LIMIT 0x00800000u /* J M D */ +#define PCRE2_EXTENDED_MORE 0x01000000u /* C */ /* These are for pcre2_jit_compile(). */ @@ -268,6 +269,7 @@ numbers must not be changed. */ #define PCRE2_ERROR_BADSUBSPATTERN (-60) #define PCRE2_ERROR_TOOMANYREPLACE (-61) #define PCRE2_ERROR_BADSERIALIZEDDATA (-62) +#define PCRE2_ERROR_HEAPLIMIT (-63) /* Request types for pcre2_pattern_info() */ @@ -297,6 +299,7 @@ numbers must not be changed. */ #define PCRE2_INFO_SIZE 22 #define PCRE2_INFO_HASBACKSLASHC 23 #define PCRE2_INFO_FRAMESIZE 24 +#define PCRE2_INFO_HEAPLIMIT 25 /* Request types for pcre2_config(). */ @@ -313,6 +316,7 @@ numbers must not be changed. */ #define PCRE2_CONFIG_UNICODE 9 #define PCRE2_CONFIG_UNICODE_VERSION 10 #define PCRE2_CONFIG_VERSION 11 +#define PCRE2_CONFIG_HEAPLIMIT 12 /* Types for code units in patterns and subject strings. */ @@ -453,6 +457,8 @@ PCRE2_EXP_DECL int PCRE2_CALL_CONVENTION \ PCRE2_EXP_DECL int PCRE2_CALL_CONVENTION \ pcre2_set_depth_limit(pcre2_match_context *, uint32_t); \ PCRE2_EXP_DECL int PCRE2_CALL_CONVENTION \ + pcre2_set_heap_limit(pcre2_match_context *, uint32_t); \ +PCRE2_EXP_DECL int PCRE2_CALL_CONVENTION \ pcre2_set_match_limit(pcre2_match_context *, uint32_t); \ PCRE2_EXP_DECL int PCRE2_CALL_CONVENTION \ pcre2_set_offset_limit(pcre2_match_context *, PCRE2_SIZE); \ @@ -676,6 +682,7 @@ pcre2_compile are called by application code. */ #define pcre2_set_character_tables PCRE2_SUFFIX(pcre2_set_character_tables_) #define pcre2_set_compile_recursion_guard PCRE2_SUFFIX(pcre2_set_compile_recursion_guard_) #define pcre2_set_depth_limit PCRE2_SUFFIX(pcre2_set_depth_limit_) +#define pcre2_set_heap_limit PCRE2_SUFFIX(pcre2_set_heap_limit_) #define pcre2_set_match_limit PCRE2_SUFFIX(pcre2_set_match_limit_) #define pcre2_set_max_pattern_length PCRE2_SUFFIX(pcre2_set_max_pattern_length_) #define pcre2_set_newline PCRE2_SUFFIX(pcre2_set_newline_) diff --git a/src/pcre2.h.in b/src/pcre2.h.in index fb0042b..2411217 100644 --- a/src/pcre2.h.in +++ b/src/pcre2.h.in @@ -137,6 +137,7 @@ D is inspected during pcre2_dfa_match() execution #define PCRE2_ALT_CIRCUMFLEX 0x00200000u /* J M D */ #define PCRE2_ALT_VERBNAMES 0x00400000u /* C */ #define PCRE2_USE_OFFSET_LIMIT 0x00800000u /* J M D */ +#define PCRE2_EXTENDED_MORE 0x01000000u /* C */ /* These are for pcre2_jit_compile(). */ diff --git a/src/pcre2_compile.c b/src/pcre2_compile.c index b4d7608..aa682d1 100644 --- a/src/pcre2_compile.c +++ b/src/pcre2_compile.c @@ -160,7 +160,7 @@ the length of compiled items varies with this. In the real compile phase, this workspace is not currently used. */ -#define COMPILE_WORK_SIZE (2048*LINK_SIZE) /* Size in code units */ +#define COMPILE_WORK_SIZE (3000*LINK_SIZE) /* Size in code units */ #define C16_WORK_SIZE \ ((COMPILE_WORK_SIZE * sizeof(PCRE2_UCHAR))/sizeof(uint16_t)) @@ -695,7 +695,8 @@ static int posix_substitutes[] = { #define PUBLIC_COMPILE_OPTIONS \ (PCRE2_ANCHORED|PCRE2_ALLOW_EMPTY_CLASS|PCRE2_ALT_BSUX|PCRE2_ALT_CIRCUMFLEX| \ PCRE2_ALT_VERBNAMES|PCRE2_AUTO_CALLOUT|PCRE2_CASELESS|PCRE2_DOLLAR_ENDONLY| \ - PCRE2_DOTALL|PCRE2_DUPNAMES|PCRE2_ENDANCHORED|PCRE2_EXTENDED|PCRE2_FIRSTLINE| \ + PCRE2_DOTALL|PCRE2_DUPNAMES|PCRE2_ENDANCHORED|PCRE2_EXTENDED| \ + PCRE2_EXTENDED_MORE|PCRE2_FIRSTLINE| \ PCRE2_MATCH_UNSET_BACKREF|PCRE2_MULTILINE|PCRE2_NEVER_BACKSLASH_C| \ PCRE2_NEVER_UCP|PCRE2_NEVER_UTF|PCRE2_NO_AUTO_CAPTURE| \ PCRE2_NO_AUTO_POSSESS|PCRE2_NO_DOTSTAR_ANCHOR|PCRE2_NO_START_OPTIMIZE| \ @@ -2226,12 +2227,17 @@ typedef struct nest_save { uint16_t reset_group; uint16_t max_group; uint16_t flags; + uint32_t options; } nest_save; -#define NSF_RESET 0x0001u -#define NSF_EXTENDED 0x0002u -#define NSF_DUPNAMES 0x0004u -#define NSF_CONDASSERT 0x0008u +#define NSF_RESET 0x0001u +#define NSF_CONDASSERT 0x0002u + +/* These options (changeable within the pattern) are tracked during parsing. +The rest are put into META_OPTIONS items and used when compiling. */ + +#define PARSE_TRACKED_OPTIONS \ + (PCRE2_EXTENDED|PCRE2_EXTENDED_MORE|PCRE2_DUPNAMES) /* States used for analyzing ranges in character classes. The two OK values must be last. */ @@ -2291,6 +2297,10 @@ creating a nest_save that spans the end of the workspace. */ end_nests = (nest_save *)((char *)end_nests - ((cb->workspace_size * sizeof(PCRE2_UCHAR)) % sizeof(nest_save))); + +/* PCRE2_EXTENDED_MORE implies PCRE2_EXTENDED */ + +if ((options & PCRE2_EXTENDED_MORE) != 0) options |= PCRE2_EXTENDED; /* Now scan the pattern */ @@ -2907,7 +2917,8 @@ while (ptr < ptrend) /* Process a regular character class. If the first character is '^', set the negation flag. If the first few characters (either before or after ^) - are \Q\E or \E we skip them too. This makes for compatibility with Perl. */ + are \Q\E or \E or space or tab in extended-more mode, we skip them too. + This makes for compatibility with Perl. */ negate_class = FALSE; while (ptr < ptrend) @@ -2922,6 +2933,9 @@ while (ptr < ptrend) else break; } + else if ((options & PCRE2_EXTENDED_MORE) != 0 && + (c == CHAR_SPACE || c == CHAR_HT)) /* Note: just these two */ + continue; else if (!negate_class && c == CHAR_CIRCUMFLEX_ACCENT) negate_class = TRUE; else break; @@ -2955,7 +2969,7 @@ while (ptr < ptrend) for (;;) { BOOL char_is_literal = TRUE; - + /* Inside \Q...\E everything is literal except \E */ if (inescq) @@ -2968,6 +2982,12 @@ while (ptr < ptrend) } goto CLASS_LITERAL; } + + /* Skip over space and tab (only) in extended-more mode. */ + + if ((options & PCRE2_EXTENDED_MORE) != 0 && + (c == CHAR_SPACE || c == CHAR_HT)) + goto CLASS_CONTINUE; /* Handle POSIX class names. Perl allows a negation extension of the form [:^name:]. A square bracket that doesn't match the syntax is @@ -3387,8 +3407,7 @@ while (ptr < ptrend) } top_nest->nest_depth = nest_depth; top_nest->flags = 0; - if ((options & PCRE2_EXTENDED) != 0) top_nest->flags |= NSF_EXTENDED; - if ((options & PCRE2_DUPNAMES) != 0) top_nest->flags |= NSF_DUPNAMES; + top_nest->options = options & PARSE_TRACKED_OPTIONS; /* Start of non-capturing group that resets the capture count for each branch. */ @@ -3403,9 +3422,9 @@ while (ptr < ptrend) ptr++; } - /* Scan for options imsxJU. We need to keep track of (?x) and (?J) for - use while scanning. The other options are used during the compiling - phases. */ + /* Scan for options imsxJU. Some of them are tracked during parsing (see + PARSE_TRACKED_OPTIONS) as they are local to groups. Others are not needed + till compile time. */ else { @@ -3429,8 +3448,14 @@ while (ptr < ptrend) case CHAR_i: *optset |= PCRE2_CASELESS; break; case CHAR_m: *optset |= PCRE2_MULTILINE; break; case CHAR_s: *optset |= PCRE2_DOTALL; break; - case CHAR_x: *optset |= PCRE2_EXTENDED; break; case CHAR_U: *optset |= PCRE2_UNGREEDY; break; + + /* If x appears twice it sets the extended extended option. */ + + case CHAR_x: + *optset |= ((*optset & PCRE2_EXTENDED) != 0)? + PCRE2_EXTENDED_MORE : PCRE2_EXTENDED; + break; default: errorcode = ERR11; @@ -3439,6 +3464,10 @@ while (ptr < ptrend) } } options = (options | set) & (~unset); + + /* Unsetting extended should also get rid of extended-more. */ + + if ((options & PCRE2_EXTENDED) == 0) options &= ~PCRE2_EXTENDED_MORE; /* If the options ended with ')' this is not the start of a nested group with option changes, so the options change at this level. @@ -3916,8 +3945,7 @@ while (ptr < ptrend) } top_nest->nest_depth = nest_depth; top_nest->flags = NSF_CONDASSERT; - if ((options & PCRE2_EXTENDED) != 0) top_nest->flags |= NSF_EXTENDED; - if ((options & PCRE2_DUPNAMES) != 0) top_nest->flags |= NSF_DUPNAMES; + top_nest->options = options & PARSE_TRACKED_OPTIONS; } break; @@ -4038,20 +4066,17 @@ while (ptr < ptrend) break; /* End of group; reset the capture count to the maximum if we are in a (?| - group and/or reset the extended and dupnames options. Disallow quantifier - for a condition that is an assertion. */ + group and/or reset the options that are tracked during parsing. Disallow + quantifier for a condition that is an assertion. */ case CHAR_RIGHT_PARENTHESIS: okquantifier = TRUE; if (top_nest != NULL && top_nest->nest_depth == nest_depth) { + options = (options & ~PARSE_TRACKED_OPTIONS) | top_nest->options; if ((top_nest->flags & NSF_RESET) != 0 && top_nest->max_group > cb->bracount) cb->bracount = top_nest->max_group; - if ((top_nest->flags & NSF_EXTENDED) != 0) options |= PCRE2_EXTENDED; - else options &= ~PCRE2_EXTENDED; - if ((top_nest->flags & NSF_DUPNAMES) != 0) options |= PCRE2_DUPNAMES; - else options &= ~PCRE2_DUPNAMES; if ((top_nest->flags & NSF_CONDASSERT) != 0) okquantifier = FALSE; if (top_nest == (nest_save *)(cb->start_workspace)) top_nest = NULL; diff --git a/src/pcre2test.c b/src/pcre2test.c index 63ab73e..e41bfff 100644 --- a/src/pcre2test.c +++ b/src/pcre2test.c @@ -580,6 +580,7 @@ static modstruct modlist[] = { { "endanchored", MOD_PD, MOD_OPT, PCRE2_ENDANCHORED, PD(options) }, { "expand", MOD_PAT, MOD_CTL, CTL_EXPAND, PO(control) }, { "extended", MOD_PATP, MOD_OPT, PCRE2_EXTENDED, PO(options) }, + { "extended_more", MOD_PATP, MOD_OPT, PCRE2_EXTENDED_MORE, PO(options) }, { "find_limits", MOD_DAT, MOD_CTL, CTL_FINDLIMITS, DO(control) }, { "firstline", MOD_PAT, MOD_OPT, PCRE2_FIRSTLINE, PO(options) }, { "framesize", MOD_PAT, MOD_CTL, CTL_FRAMESIZE, PO(control) }, @@ -3464,7 +3465,17 @@ for (;;) field = check_modifier(modlist + index, ctx, pctl, dctl, *p); if (field == NULL) return FALSE; - *((uint32_t *)field) |= modlist[index].value; + + /* /x is a special case; a second appearance changes PCRE2_EXTENDED to + PCRE2_EXTENDED_MORE. */ + + if (cc == 'x' && (*((uint32_t *)field) & PCRE2_EXTENDED) != 0) + { + *((uint32_t *)field) &= ~PCRE2_EXTENDED; + *((uint32_t *)field) |= PCRE2_EXTENDED_MORE; + } + else + *((uint32_t *)field) |= modlist[index].value; } continue; /* With tne next (fullname) modifier */ @@ -3842,7 +3853,7 @@ static void show_compile_options(uint32_t options, const char *before, const char *after) { if (options == 0) fprintf(outfile, "%s <none>%s", before, after); -else fprintf(outfile, "%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s", +else fprintf(outfile, "%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s", before, ((options & PCRE2_ALT_BSUX) != 0)? " alt_bsux" : "", ((options & PCRE2_ALT_CIRCUMFLEX) != 0)? " alt_circumflex" : "", @@ -3856,6 +3867,7 @@ else fprintf(outfile, "%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s% ((options & PCRE2_DUPNAMES) != 0)? " dupnames" : "", ((options & PCRE2_ENDANCHORED) != 0)? " endanchored" : "", ((options & PCRE2_EXTENDED) != 0)? " extended" : "", + ((options & PCRE2_EXTENDED_MORE) != 0)? " extended_more" : "", ((options & PCRE2_FIRSTLINE) != 0)? " firstline" : "", ((options & PCRE2_MATCH_UNSET_BACKREF) != 0)? " match_unset_backref" : "", ((options & PCRE2_MULTILINE) != 0)? " multiline" : "", diff --git a/testdata/testinput2 b/testdata/testinput2 index 57e9521..8afde1b 100644 --- a/testdata/testinput2 +++ b/testdata/testinput2 @@ -5245,4 +5245,18 @@ a)"xI # ---------------------------------------------------------------------- +/[a b c]/BxxI + +/[a b c]/BxxxI + +/[a b c]/B,extended_more + +/[ a b c ]/B,extended_more + +/[a b](?xx: [ 12 ] (?-xx:[ 34 ]) )y z/B + +# Unsetting /x also unsets /xx + +/[a b](?xx: [ 12 ] (?-x:[ 34 ]) )y z/B + # End of testinput2 diff --git a/testdata/testoutput2 b/testdata/testoutput2 index f81d85a..dff7657 100644 --- a/testdata/testoutput2 +++ b/testdata/testoutput2 @@ -15873,6 +15873,78 @@ Failed: error -37: callout error code # ---------------------------------------------------------------------- +/[a b c]/BxxI +------------------------------------------------------------------ + Bra + [a-c] + Ket + End +------------------------------------------------------------------ +Capturing subpattern count = 0 +Options: extended_more +Starting code units: a b c +Subject length lower bound = 1 + +/[a b c]/BxxxI +------------------------------------------------------------------ + Bra + [a-c] + Ket + End +------------------------------------------------------------------ +Capturing subpattern count = 0 +Options: extended extended_more +Starting code units: a b c +Subject length lower bound = 1 + +/[a b c]/B,extended_more +------------------------------------------------------------------ + Bra + [a-c] + Ket + End +------------------------------------------------------------------ + +/[ a b c ]/B,extended_more +------------------------------------------------------------------ + Bra + [a-c] + Ket + End +------------------------------------------------------------------ + +/[a b](?xx: [ 12 ] (?-xx:[ 34 ]) )y z/B +------------------------------------------------------------------ + Bra + [ ab] + Bra + [12] + Bra + [ 34] + Ket + Ket + y z + Ket + End +------------------------------------------------------------------ + +# Unsetting /x also unsets /xx + +/[a b](?xx: [ 12 ] (?-x:[ 34 ]) )y z/B +------------------------------------------------------------------ + Bra + [ ab] + Bra + [12] + Bra + [ 34] + Ket + Ket + y z + Ket + End +------------------------------------------------------------------ + # End of testinput2 Error -64: PCRE2_ERROR_BADDATA (unknown error number) Error -62: bad serialized data diff --git a/testdata/testoutput8-16-2 b/testdata/testoutput8-16-2 index 02b6dfc..47c9e56 100644 --- a/testdata/testoutput8-16-2 +++ b/testdata/testoutput8-16-2 @@ -846,7 +846,7 @@ Memory allocation (code space): 14 /(?|(?|(?J:(?|(?x:(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?| ))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))) /parens_nest_limit=1000,-fullbincode -Failed: error 184 at offset 1540: (?| and/or (?J: or (?x: parentheses are too deeply nested +Failed: error 184 at offset 1504: (?| and/or (?J: or (?x: parentheses are too deeply nested # Use "expand" to create some very long patterns with nested parentheses, in # order to test workspace overflow. Again, this varies with code unit width, @@ -854,10 +854,8 @@ Failed: error 184 at offset 1540: (?| and/or (?J: or (?x: parentheses are too de # with link size - hence multiple tests with different values. /(?'ABC'\[[bar](]{792}*THEN:\[A]{255}\[)]{793}/expand,-fullbincode,parens_nest_limit=1000 -Failed: error 186 at offset 5813: regular expression is too complicated /(?'ABC'\[[bar](]{793}*THEN:\[A]{255}\[)]{794}/expand,-fullbincode,parens_nest_limit=1000 -Failed: error 186 at offset 5820: regular expression is too complicated /(?'ABC'\[[bar](]{1793}*THEN:\[A]{255}\[)]{1794}/expand,-fullbincode,parens_nest_limit=2000 Failed: error 186 at offset 12820: regular expression is too complicated diff --git a/testdata/testoutput8-32-2 b/testdata/testoutput8-32-2 index 83e3086..30667a3 100644 --- a/testdata/testoutput8-32-2 +++ b/testdata/testoutput8-32-2 @@ -853,10 +853,8 @@ Memory allocation (code space): 28 # with link size - hence multiple tests with different values. /(?'ABC'\[[bar](]{792}*THEN:\[A]{255}\[)]{793}/expand,-fullbincode,parens_nest_limit=1000 -Failed: error 186 at offset 5813: regular expression is too complicated /(?'ABC'\[[bar](]{793}*THEN:\[A]{255}\[)]{794}/expand,-fullbincode,parens_nest_limit=1000 -Failed: error 186 at offset 5820: regular expression is too complicated /(?'ABC'\[[bar](]{1793}*THEN:\[A]{255}\[)]{1794}/expand,-fullbincode,parens_nest_limit=2000 Failed: error 186 at offset 12820: regular expression is too complicated diff --git a/testdata/testoutput8-8-2 b/testdata/testoutput8-8-2 index 6dbd83a..4b03356 100644 --- a/testdata/testoutput8-8-2 +++ b/testdata/testoutput8-8-2 @@ -846,7 +846,7 @@ Memory allocation (code space): 10 /(?|(?|(?J:(?|(?x:(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?|(?| ))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))) /parens_nest_limit=1000,-fullbincode -Failed: error 184 at offset 1540: (?| and/or (?J: or (?x: parentheses are too deeply nested +Failed: error 184 at offset 1504: (?| and/or (?J: or (?x: parentheses are too deeply nested # Use "expand" to create some very long patterns with nested parentheses, in # order to test workspace overflow. Again, this varies with code unit width, @@ -856,7 +856,6 @@ Failed: error 184 at offset 1540: (?| and/or (?J: or (?x: parentheses are too de /(?'ABC'\[[bar](]{792}*THEN:\[A]{255}\[)]{793}/expand,-fullbincode,parens_nest_limit=1000 /(?'ABC'\[[bar](]{793}*THEN:\[A]{255}\[)]{794}/expand,-fullbincode,parens_nest_limit=1000 -Failed: error 186 at offset 5820: regular expression is too complicated /(?'ABC'\[[bar](]{1793}*THEN:\[A]{255}\[)]{1794}/expand,-fullbincode,parens_nest_limit=2000 Failed: error 186 at offset 12820: regular expression is too complicated |