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| author | ph10 <ph10@6239d852-aaf2-0410-a92c-79f79f948069> | 2020-02-16 17:47:14 +0000 |
|---|---|---|
| committer | ph10 <ph10@6239d852-aaf2-0410-a92c-79f79f948069> | 2020-02-16 17:47:14 +0000 |
| commit | f22e85edd01a9d72d69a3c3cf075d6b7b89213c2 (patch) | |
| tree | da9fec087e73d2ac97bf7d2cee433a3fcea33124 | |
| parent | 56dcf82df850f332a0458b03088ab61850810a01 (diff) | |
| download | pcre2-f22e85edd01a9d72d69a3c3cf075d6b7b89213c2.tar.gz | |
Documentation update.
git-svn-id: svn://vcs.exim.org/pcre2/code/trunk@1220 6239d852-aaf2-0410-a92c-79f79f948069
| -rw-r--r-- | doc/html/pcre2api.html | 100 | ||||
| -rw-r--r-- | doc/pcre2.txt | 461 |
2 files changed, 288 insertions, 273 deletions
diff --git a/doc/html/pcre2api.html b/doc/html/pcre2api.html index 5903c8d..9562a26 100644 --- a/doc/html/pcre2api.html +++ b/doc/html/pcre2api.html @@ -3309,13 +3309,13 @@ can be given as PCRE2_ZERO_TERMINATED for a zero-terminated string. There is an option (see PCRE2_SUBSTITUTE_REPLACEMENT_ONLY below) to return just the replacement string(s). The default action is to perform just one replacement if the pattern matches, but there is an option that requests multiple replacements -(see PCRE2_SUBSTITUTE_GLOBAL below for details). +(see PCRE2_SUBSTITUTE_GLOBAL below). </P> <P> If successful, <b>pcre2_substitute()</b> returns the number of substitutions that were carried out. This may be zero if no match was found, and is never greater than one unless PCRE2_SUBSTITUTE_GLOBAL is set. A negative value is -returned if an error is detected (see below for details). +returned if an error is detected. </P> <P> Matches in which a \K item in a lookahead in the pattern causes the match to @@ -3333,10 +3333,11 @@ functions from the match context, if provided, or else those that were used to allocate memory for the compiled code. </P> <P> -If an external <i>match_data</i> block is provided, its contents afterwards -are those set by the final call to <b>pcre2_match()</b>. For global changes, -this will have ended in a no-match error. The contents of the ovector within -the match data block may or may not have been changed. +If <i>match_data</i> is not NULL and PCRE2_SUBSTITUTE_MATCHED is not set, the +provided block is used for all calls to <b>pcre2_match()</b>, and its contents +afterwards are the result of the final call. For global changes, this will +always be a no-match error. The contents of the ovector within the match data +block may or may not have been changed. </P> <P> As well as the usual options for <b>pcre2_match()</b>, a number of additional @@ -3350,45 +3351,68 @@ an application to check for a match before choosing to substitute, without having to repeat the match. </P> <P> -The <i>code</i> argument is not used for the first substitution when -PCRE2_SUBSTITUTE_MATCHED is set, but if PCRE2_SUBSTITUTE_GLOBAL is also set, -<b>pcre2_match()</b> will be called after the first substitution to check for -further matches, and the contents of the <i>match_data</i> block will be -changed. +The contents of the externally supplied match data block are not changed when +PCRE2_SUBSTITUTE_MATCHED is set. If PCRE2_SUBSTITUTE_GLOBAL is also set, +<b>pcre2_match()</b> is called after the first substitution to check for further +matches, but this is done using an internally obtained match data block, thus +always leaving the external block unchanged. </P> <P> -The default is to return a copy of the subject string with matched substrings -replaced. However, if PCRE2_SUBSTITUTE_REPLACEMENT_ONLY is set, only the -replacement substrings are returned. In the global case, multiple replacements -are concatenated in the output buffer. Substitution callouts (see +The <i>code</i> argument is not used for matching before the first substitution +when PCRE2_SUBSTITUTE_MATCHED is set, but it must be provided, even when +PCRE2_SUBSTITUTE_GLOBAL is not set, because it contains information such as the +UTF setting and the number of capturing parentheses in the pattern. +</P> +<P> +The default action of <b>pcre2_substitute()</b> is to return a copy of the +subject string with matched substrings replaced. However, if +PCRE2_SUBSTITUTE_REPLACEMENT_ONLY is set, only the replacement substrings are +returned. In the global case, multiple replacements are concatenated in the +output buffer. Substitution callouts (see <a href="#subcallouts">below)</a> can be used to separate them if necessary. </P> <P> The <i>outlengthptr</i> argument of <b>pcre2_substitute()</b> must point to a variable that contains the length, in code units, of the output buffer. If the -function is successful, the value is updated to contain the length of the new -string, excluding the trailing zero that is automatically added. +function is successful, the value is updated to contain the length in code +units of the new string, excluding the trailing zero that is automatically +added. </P> <P> If the function is not successful, the value set via <i>outlengthptr</i> 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, -<b>pcre2_substitute()</b> 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. +output buffer being too small, unless PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set. +</P> +<P> +PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output buffer is +too small. The default action is to return PCRE2_ERROR_NOMEMORY immediately. If +this option is set, however, <b>pcre2_substitute()</b> continues to go through +the motions of matching and substituting (without, of course, writing anything) +in order to compute the size of buffer that is needed. This value is passed +back via the <i>outlengthptr</i> variable, with the result of the function still +being PCRE2_ERROR_NOMEMORY. +</P> +<P> +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 application, it may be more +efficient to allocate a large buffer and free the excess afterwards, instead of +using PCRE2_SUBSTITUTE_OVERFLOW_LENGTH. </P> <P> -The replacement string, which is interpreted as a UTF string in UTF mode, -is checked for UTF validity unless the PCRE2_NO_UTF_CHECK option is set. If the -PCRE2_SUBSTITUTE_LITERAL option is set, it is not interpreted in any way. By -default, however, a dollar character is an escape character that can specify -the insertion of characters from capture groups and names from (*MARK) or other -control verbs in the pattern. The following forms are always recognized: +The replacement string, which is interpreted as a UTF string in UTF mode, is +checked for UTF validity unless PCRE2_NO_UTF_CHECK is set. An invalid UTF +replacement string causes an immediate return with the relevant UTF error code. +</P> +<P> +If PCRE2_SUBSTITUTE_LITERAL is set, the replacement string is not interpreted +in any way. By default, however, a dollar character is an escape character that +can specify the insertion of characters from capture groups and names from +(*MARK) or other control verbs in the pattern. The following forms are always +recognized: <pre> $$ insert a dollar character $<n> or ${<n>} insert the contents of group <n> @@ -3436,22 +3460,6 @@ CRLF is a valid newline sequence and the next two characters are CR, LF. In this case, the offset is advanced by two characters. </P> <P> -PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output buffer is -too small. The default action is to return PCRE2_ERROR_NOMEMORY immediately. If -this option is set, however, <b>pcre2_substitute()</b> continues to go through -the motions of matching and substituting (without, of course, writing anything) -in order to compute the size of buffer that is needed. This value is passed -back via the <i>outlengthptr</i> variable, with the result of the function still -being PCRE2_ERROR_NOMEMORY. -</P> -<P> -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 application, it may be more -efficient to allocate a large buffer and free the excess afterwards, instead of -using PCRE2_SUBSTITUTE_OVERFLOW_LENGTH. -</P> -<P> PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capture 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 @@ -3907,7 +3915,7 @@ Cambridge, England. </P> <br><a name="SEC42" href="#TOC1">REVISION</a><br> <P> -Last updated: 22 January 2020 +Last updated: 16 February 2020 <br> Copyright © 1997-2020 University of Cambridge. <br> diff --git a/doc/pcre2.txt b/doc/pcre2.txt index a05a57f..3a36f00 100644 --- a/doc/pcre2.txt +++ b/doc/pcre2.txt @@ -3200,13 +3200,13 @@ CREATING A NEW STRING WITH SUBSTITUTIONS There is an option (see PCRE2_SUBSTITUTE_REPLACEMENT_ONLY below) to re- turn just the replacement string(s). The default action is to perform just one replacement if the pattern matches, but there is an option - that requests multiple replacements (see PCRE2_SUBSTITUTE_GLOBAL below - for details). + that requests multiple replacements (see PCRE2_SUBSTITUTE_GLOBAL be- + low). If successful, pcre2_substitute() returns the number of substitutions that were carried out. This may be zero if no match was found, and is never greater than one unless PCRE2_SUBSTITUTE_GLOBAL is set. A nega- - tive value is returned if an error is detected (see below for details). + tive value is returned if an error is detected. Matches in 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 @@ -3221,75 +3221,98 @@ CREATING A NEW STRING WITH SUBSTITUTIONS ment functions from the match context, if provided, or else those that were used to allocate memory for the compiled code. - If an external match_data block is provided, its contents afterwards - are those set by the final call to pcre2_match(). For global changes, - this will have ended in a no-match error. The contents of the ovector - within the match data block may or may not have been changed. - - As well as the usual options for pcre2_match(), a number of additional - options can be set in the options argument of pcre2_substitute(). One - such option is PCRE2_SUBSTITUTE_MATCHED. When this is set, an external - match_data block must be provided, and it must have been used for an - external call to pcre2_match(). The data in the match_data block (re- + If match_data is not NULL and PCRE2_SUBSTITUTE_MATCHED is not set, the + provided block is used for all calls to pcre2_match(), and its contents + afterwards are the result of the final call. For global changes, this + will always be a no-match error. The contents of the ovector within the + match data block may or may not have been changed. + + As well as the usual options for pcre2_match(), a number of additional + options can be set in the options argument of pcre2_substitute(). One + such option is PCRE2_SUBSTITUTE_MATCHED. When this is set, an external + match_data block must be provided, and it must have been used for an + external call to pcre2_match(). The data in the match_data block (re- turn code, offset vector) is used for the first substitution instead of - calling pcre2_match() from within pcre2_substitute(). This allows an + calling pcre2_match() from within pcre2_substitute(). This allows an application to check for a match before choosing to substitute, without having to repeat the match. - The code argument is not used for the first substitution when - PCRE2_SUBSTITUTE_MATCHED is set, but if PCRE2_SUBSTITUTE_GLOBAL is also - set, pcre2_match() will be called after the first substitution to check - for further matches, and the contents of the match_data block will be - changed. - - The default is to return a copy of the subject string with matched sub- - strings replaced. However, if PCRE2_SUBSTITUTE_REPLACEMENT_ONLY is set, - only the replacement substrings are returned. In the global case, mul- - tiple replacements are concatenated in the output buffer. Substitution - callouts (see below) can be used to separate them if necessary. - - The outlengthptr argument of pcre2_substitute() must point to a vari- - able that contains the length, in code units, of the output buffer. If - the function is successful, 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 de- - pends on the type of error. For syntax errors in the replacement + The contents of the externally supplied match data block are not + changed when PCRE2_SUBSTITUTE_MATCHED is set. If PCRE2_SUBSTI- + TUTE_GLOBAL is also set, pcre2_match() is called after the first sub- + stitution to check for further matches, but this is done using an in- + ternally obtained match data block, thus always leaving the external + block unchanged. + + The code argument is not used for matching before the first substitu- + tion when PCRE2_SUBSTITUTE_MATCHED is set, but it must be provided, + even when PCRE2_SUBSTITUTE_GLOBAL is not set, because it contains in- + formation such as the UTF setting and the number of capturing parenthe- + ses in the pattern. + + The default action of pcre2_substitute() is to return a copy of the + subject string with matched substrings replaced. However, if PCRE2_SUB- + STITUTE_REPLACEMENT_ONLY is set, only the replacement substrings are + returned. In the global case, multiple replacements are concatenated in + the output buffer. Substitution callouts (see below) can be used to + separate them if necessary. + + The outlengthptr argument of pcre2_substitute() must point to a vari- + able that contains the length, in code units, of the output buffer. If + the function is successful, the value is updated to contain the length + in code units of the new string, excluding the trailing zero that is + automatically added. + + If the function is not successful, the value set via outlengthptr de- + pends on the type of error. For syntax errors in the replacement string, the value is the offset in the replacement string where the er- - ror was detected. For other errors, the value is PCRE2_UNSET by de- + ror was detected. For other errors, the value is PCRE2_UNSET by de- fault. This includes the case of the output buffer being too small, un- - less PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which case - the value is the minimum length needed, including space for the trail- - ing zero. Note that in order to compute the required length, pcre2_sub- - stitute() has to simulate all the matching and copying, instead of giv- - ing an error return as soon as the buffer overflows. Note also that the - length is in code units, not bytes. + less PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set. + + 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() + 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 PCRE2_ER- + ROR_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 + 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- + FLOW_LENGTH. The replacement string, which is interpreted as a UTF string in UTF - mode, is checked for UTF validity unless the PCRE2_NO_UTF_CHECK option - is set. If the PCRE2_SUBSTITUTE_LITERAL option is set, it is not inter- - preted in any way. By default, however, a dollar character is an escape - character that can specify the insertion of characters from capture - groups and names from (*MARK) or other control verbs in the pattern. - The following forms are always recognized: + mode, is checked for UTF validity unless PCRE2_NO_UTF_CHECK is set. An + invalid UTF replacement string causes an immediate return with the rel- + evant UTF error code. + + If PCRE2_SUBSTITUTE_LITERAL is set, the replacement string is not in- + terpreted in any way. By default, however, a dollar character is an es- + cape character that can specify the insertion of characters from cap- + ture groups and names from (*MARK) or other control verbs in the pat- + tern. The following forms are always recognized: $$ insert a dollar character $<n> or ${<n>} insert the contents of group <n> $*MARK or ${*MARK} insert a control verb name - 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+=". - $*MARK inserts the name from the last encountered backtracking control - verb on the matching path that has a name. (*MARK) must always include - a name, but the other verbs need not. For example, in the case of + $*MARK inserts the name from the last encountered backtracking control + verb on the matching path that has a name. (*MARK) must always include + a name, but the other verbs need not. For example, in the case of (*MARK:A)(*PRUNE) the name inserted is "A", but for (*MARK:A)(*PRUNE:B) - the relevant name is "B". This facility can be used to perform simple + the relevant name is "B". This facility can be used to perform simple simultaneous substitutions, as this pcre2test example shows: /(*MARK:pear)apple|(*MARK:orange)lemon/g,replace=${*MARK} @@ -3297,15 +3320,15 @@ CREATING A NEW STRING WITH SUBSTITUTIONS 2: pear orange PCRE2_SUBSTITUTE_GLOBAL causes the function to iterate over the subject - string, replacing every matching substring. If this option is not set, - only the first matching substring is replaced. The search for matches - takes place in the original subject string (that is, previous replace- - ments do not affect it). Iteration is implemented by advancing the - startoffset value for each search, which is always passed the entire + string, replacing every matching substring. If this option is not set, + only the first matching substring is replaced. The search for matches + takes place in the original subject string (that is, previous replace- + ments do not affect it). Iteration is implemented by advancing the + startoffset value for each search, which is always passed the entire subject string. If an offset limit is set in the match context, search- ing stops when that limit is reached. - You can restrict the effect of a global substitution to a portion of + You can restrict the effect of a global substitution to a portion of the subject string by setting either or both of startoffset and an off- set limit. Here is a pcre2test example: @@ -3313,87 +3336,71 @@ CREATING A NEW STRING WITH SUBSTITUTIONS ABC ABC ABC ABC\=offset=3,offset_limit=12 2: ABC A!C A!C ABC - When continuing with global substitutions after matching a substring + When continuing with global substitutions after matching a substring with zero length, an attempt to find a non-empty match at the same off- set is performed. If this is not successful, the offset 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 offset is advanced by two + two characters are CR, LF. In this case, the offset is advanced by two characters. - 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() - 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 PCRE2_ER- - ROR_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 - 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- - FLOW_LENGTH. - PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capture 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 + 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 capture groups (including un- - known groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be treated - as empty strings when inserted as described above. If this option is + known 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_UN- - SET error. This option does not influence the extended substitution + SET 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 capture groups and let- + all inserted characters, including those from capture 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 - \E has no effect. Note also that the PCRE2_ALT_BSUX and PCRE2_EX- + ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final + \E has no effect. Note also that the PCRE2_ALT_BSUX and PCRE2_EX- TRA_ALT_BSUX options do not apply to replacement strings. - The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more - flexibility to capture group substitution. The syntax is similar to + The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more + flexibility to capture 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 @@ -3402,8 +3409,8 @@ 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 un- + The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended + substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause un- known groups in the extended syntax forms to be treated as unset. If PCRE2_SUBSTITUTE_LITERAL is set, PCRE2_SUBSTITUTE_UNKNOWN_UNSET, @@ -3412,37 +3419,37 @@ CREATING A NEW STRING WITH SUBSTITUTIONS Substitution errors - In the event of an error, pcre2_substitute() returns a negative error - code. Except for PCRE2_ERROR_NOMATCH (which is never returned), errors + In the event of an error, pcre2_substitute() returns a negative error + code. Except for 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) - when the simple (non-extended) syntax is used and PCRE2_SUBSTITUTE_UN- + ing an unknown substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) + when the simple (non-extended) syntax is used and PCRE2_SUBSTITUTE_UN- SET_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_NULL is returned if PCRE2_SUBSTITUTE_MATCHED is set but the match_data argument is NULL. - PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in - the replacement string, with more particular errors being PCRE2_ER- + PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in + the replacement string, with more particular errors being PCRE2_ER- ROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REPMISSINGBRACE - (closing curly bracket not found), PCRE2_ERROR_BADSUBSTITUTION (syntax - error in extended group substitution), and PCRE2_ERROR_BADSUBSPATTERN + (closing curly bracket not found), PCRE2_ERROR_BADSUBSTITUTION (syntax + error in extended group substitution), and PCRE2_ERROR_BADSUBSPATTERN (the pattern match ended before it started or the match started earlier - than the current position in the subject, which can happen if \K is + than the current position in the subject, 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 "Ob- + obtained by calling the pcre2_get_error_message() function (see "Ob- taining a textual error message" above). Substitution callouts @@ -3451,15 +3458,15 @@ CREATING A NEW STRING WITH SUBSTITUTIONS int (*callout_function)(pcre2_substitute_callout_block *, void *), void *callout_data); - The pcre2_set_substitution_callout() function can be used to specify a - callout function for pcre2_substitute(). This information is passed in + The pcre2_set_substitution_callout() function can be used to specify a + callout function for pcre2_substitute(). This information is passed in a match context. The callout function is called after each substitution has been processed, but it can cause the replacement not to happen. The - callout function is not called for simulated substitutions that happen + callout function is not called for simulated substitutions that happen as a result of the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option. The first argument of the callout function is a pointer to a substitute - callout block structure, which contains the following fields, not nec- + callout block structure, which contains the following fields, not nec- essarily in this order: uint32_t version; @@ -3470,34 +3477,34 @@ CREATING A NEW STRING WITH SUBSTITUTIONS uint32_t oveccount; PCRE2_SIZE output_offsets[2]; - The version field contains the version number of the block format. The - current version is 0. The version number will increase in future if - more fields are added, but the intention is never to remove any of the + The version field contains the version number of the block format. The + current version is 0. The version number will increase in future if + more fields are added, but the intention is never to remove any of the existing fields. The subscount field is the number of the current match. It is 1 for the first callout, 2 for the second, and so on. The input and output point- ers are copies of the values passed to pcre2_substitute(). - The ovector field points to the ovector, which contains the result of + The ovector field points to the ovector, which contains the result of the most recent match. The oveccount field contains the number of pairs that are set in the ovector, and is always greater than zero. - The output_offsets vector contains the offsets of the replacement in - the output string. This has already been processed for dollar and (if + The output_offsets vector contains the offsets of the replacement in + the output string. This has already been processed for dollar and (if requested) backslash substitutions as described above. - The second argument of the callout function is the value passed as - callout_data when the function was registered. The value returned by + The second argument of the callout function is the value passed as + callout_data when the function was registered. The value returned by the callout function is interpreted as follows: - If the value is zero, the replacement is accepted, and, if PCRE2_SUB- - STITUTE_GLOBAL is set, processing continues with a search for the next - match. If the value is not zero, the current replacement is not ac- - cepted. If the value is greater than zero, processing continues when - PCRE2_SUBSTITUTE_GLOBAL is set. Otherwise (the value is less than zero - or PCRE2_SUBSTITUTE_GLOBAL is not set), the the rest of the input is - copied to the output and the call to pcre2_substitute() exits, return- + If the value is zero, the replacement is accepted, and, if PCRE2_SUB- + STITUTE_GLOBAL is set, processing continues with a search for the next + match. If the value is not zero, the current replacement is not ac- + cepted. If the value is greater than zero, processing continues when + PCRE2_SUBSTITUTE_GLOBAL is set. Otherwise (the value is less than zero + or PCRE2_SUBSTITUTE_GLOBAL is not set), the the rest of the input is + copied to the output and the call to pcre2_substitute() exits, return- ing the number of matches so far. @@ -3506,56 +3513,56 @@ DUPLICATE CAPTURE GROUP 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 - capture groups are not required to be unique. Duplicate names are al- - ways allowed for groups with the same number, created by using the (?| + When a pattern is compiled with the PCRE2_DUPNAMES option, names for + capture groups are not required to be unique. Duplicate names are al- + ways allowed for groups with the same number, created by using the (?| feature. Indeed, if such groups are named, they are required to use the same names. - Normally, patterns that use duplicate names are such that in any one - match, only one of each set of identically-named groups participates. + Normally, patterns that use duplicate names are such that in any one + match, only one of each set of identically-named groups 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_UN- - SET is returned. The pcre2_substring_number_from_name() function re- - turns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are duplicate + 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_UN- + SET is returned. The pcre2_substring_number_from_name() function re- + turns 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. @@ -3567,26 +3574,26 @@ 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(): @@ -3606,45 +3613,45 @@ 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_COPY_MATCHED_SUBJECT, PCRE2_ENDANCHORED, PCRE2_NOTBOL, PCRE2_NO- + 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_COPY_MATCHED_SUBJECT, PCRE2_ENDANCHORED, PCRE2_NOTBOL, PCRE2_NO- TEOL, 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 + 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 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. @@ -3652,8 +3659,8 @@ 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 <.*> @@ -3668,80 +3675,80 @@ 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 capture groups that may exist in the pattern, because DFA matching + 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 capture groups that may exist in the pattern, because DFA matching does not support capturing. - Calls to the convenience functions that extract substrings by name re- + Calls to the convenience functions that extract substrings by name re- turn the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used af- - ter a DFA match. The convenience functions that extract substrings by + ter a DFA match. The convenience functions that extract substrings by number never return PCRE2_ERROR_NOSUBSTRING. - 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 re- + 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 re- ally do want multiple matches in such cases, either use an ungreedy re- - peat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when com- + peat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when com- piling. 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 backreference. PCRE2_ERROR_DFA_UCOND - This return is given if pcre2_dfa_match() encounters a condition item + This return is given if pcre2_dfa_match() encounters a condition item that uses a backreference for the condition, or a test for recursion in a specific capture group. These are not supported. PCRE2_ERROR_DFA_UINVALID_UTF - This return is given if pcre2_dfa_match() is called for a pattern that - was compiled with PCRE2_MATCH_INVALID_UTF. This is not supported for + This return is given if pcre2_dfa_match() is called for a pattern that + was compiled with PCRE2_MATCH_INVALID_UTF. This is not supported for DFA matching. 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 recursion or subroutine call 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 should be extremely rare, as a vector of size 1000 is + calls itself recursively, using private memory for the ovector and + workspace. 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). @@ -3754,7 +3761,7 @@ AUTHOR REVISION - Last updated: 22 January 2020 + Last updated: 16 February 2020 Copyright (c) 1997-2020 University of Cambridge. ------------------------------------------------------------------------------ |