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author | ph10 <ph10@2f5784b3-3f2a-0410-8824-cb99058d5e15> | 2009-09-18 19:12:35 +0000 |
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committer | ph10 <ph10@2f5784b3-3f2a-0410-8824-cb99058d5e15> | 2009-09-18 19:12:35 +0000 |
commit | 20dd865c5c8f10036cda34b9870351b702399c08 (patch) | |
tree | 3a47dd7d7162f12a80b3fc947e16292b067ffa34 /doc/pcretest.txt | |
parent | eaa446db0f399010171263221963181144b026e0 (diff) | |
download | pcre-20dd865c5c8f10036cda34b9870351b702399c08.tar.gz |
Add more explanation about recursive subpatterns, and make it possible to
process the documenation without building a whole release.
git-svn-id: svn://vcs.exim.org/pcre/code/trunk@453 2f5784b3-3f2a-0410-8824-cb99058d5e15
Diffstat (limited to 'doc/pcretest.txt')
-rw-r--r-- | doc/pcretest.txt | 296 |
1 files changed, 149 insertions, 147 deletions
diff --git a/doc/pcretest.txt b/doc/pcretest.txt index f1e8777..46df32a 100644 --- a/doc/pcretest.txt +++ b/doc/pcretest.txt @@ -196,87 +196,88 @@ PATTERN MODIFIERS or \B). If any call to pcre_exec() in a /g or /G sequence matches an empty - string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED - flags set in order to search for another, non-empty, match at the same - point. If this second match fails, the start offset is advanced by - one, and the normal match is retried. This imitates the way Perl han- - dles such cases when using the /g modifier or the split() function. + string, the next call is done with the PCRE_NOTEMPTY_ATSTART and + PCRE_ANCHORED flags set in order to search for another, non-empty, + match at the same point. If this second match fails, the start offset + is advanced by one character, and the normal match is retried. This + imitates the way Perl handles such cases when using the /g modifier or + the split() function. Other modifiers There are yet more modifiers for controlling the way pcretest operates. - The /+ modifier requests that as well as outputting the substring that - matched the entire pattern, pcretest should in addition output the - remainder of the subject string. This is useful for tests where the + The /+ modifier requests that as well as outputting the substring that + matched the entire pattern, pcretest 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 /B modifier is a debugging feature. It requests that pcretest out- - put a representation of the compiled byte code after compilation. Nor- - mally this information contains length and offset values; however, if - /Z is also present, this data is replaced by spaces. This is a special + The /B modifier is a debugging feature. It requests that pcretest out- + put a representation of the compiled byte code after compilation. Nor- + mally this information contains length and offset values; however, if + /Z is also present, this data is replaced by spaces. This is a special feature for use in the automatic test scripts; it ensures that the same output is generated for different internal link sizes. - The /L modifier must be followed directly by the name of a locale, for + The /L modifier must be followed directly by the name of a locale, for example, /pattern/Lfr_FR For this reason, it must be the last modifier. The given locale is set, - pcre_maketables() is called to build a set of character tables for the - locale, and this is then passed to pcre_compile() when compiling the - regular expression. Without an /L modifier, NULL is passed as the - tables pointer; that is, /L applies only to the expression on which it + pcre_maketables() is called to build a set of character tables for the + locale, and this is then passed to pcre_compile() when compiling the + regular expression. Without an /L modifier, NULL is passed as the + tables pointer; that is, /L applies only to the expression on which it appears. - The /I modifier requests that pcretest output information about the - compiled pattern (whether it is anchored, has a fixed first character, - and so on). It does this by calling pcre_fullinfo() after compiling a - pattern. If the pattern is studied, the results of that are also out- + The /I modifier requests that pcretest output information about the + compiled pattern (whether it is anchored, has a fixed first character, + and so on). It does this by calling pcre_fullinfo() after compiling a + pattern. If the pattern is studied, the results of that are also out- put. - The /D modifier is a PCRE debugging feature, and is equivalent to /BI, + The /D modifier is a PCRE debugging feature, and is equivalent to /BI, that is, both the /B and the /I modifiers. The /F modifier causes pcretest to flip the byte order of the fields in - the compiled pattern that contain 2-byte and 4-byte numbers. This - facility is for testing the feature in PCRE that allows it to execute + the compiled pattern that contain 2-byte and 4-byte numbers. This + facility is for testing the feature in PCRE that allows it to execute patterns that were compiled on a host with a different endianness. This - feature is not available when the POSIX interface to PCRE is being - used, that is, when the /P pattern modifier is specified. See also the + feature is not available when the POSIX interface to PCRE is being + used, that is, when the /P pattern modifier is specified. See also the section about saving and reloading compiled patterns below. - The /S modifier causes pcre_study() to be called after the expression + The /S modifier causes pcre_study() to be called after the expression has been compiled, and the results used when the expression is matched. - The /M modifier causes the size of memory block used to hold the com- + The /M modifier causes the size of memory block used to hold the com- piled pattern to be output. - The /P modifier causes pcretest to call PCRE via the POSIX wrapper API - rather than its native API. When this is done, all other modifiers - except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present, - and REG_NEWLINE is set if /m is present. The wrapper functions force + The /P modifier causes pcretest to call PCRE via the POSIX wrapper API + rather than its native API. When this is done, all other modifiers + except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present, + and REG_NEWLINE is set if /m is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set. - The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option - set. This turns on support for UTF-8 character handling in PCRE, pro- - vided that it was compiled with this support enabled. This modifier + The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option + set. This turns on support for UTF-8 character handling in PCRE, pro- + vided that it was compiled with this support enabled. This modifier also causes any non-printing characters in output strings to be printed using the \x{hh...} notation if they are valid UTF-8 sequences. - If the /? modifier is used with /8, it causes pcretest to call - pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the + If the /? modifier is used with /8, it causes pcretest to call + pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the checking of the string for UTF-8 validity. DATA LINES - Before each data line is passed to pcre_exec(), leading and trailing - whitespace is removed, and it is then scanned for \ escapes. Some of - these are pretty esoteric features, intended for checking out some of - the more complicated features of PCRE. If you are just testing "ordi- - nary" regular expressions, you probably don't need any of these. The + Before each data line is passed to pcre_exec(), leading and trailing + whitespace is removed, and it is then scanned for \ escapes. Some of + these are pretty esoteric features, intended for checking out some of + the more complicated features of PCRE. If you are just testing "ordi- + nary" regular expressions, you probably don't need any of these. The following escapes are recognized: \a alarm (BEL, \x07) @@ -323,7 +324,8 @@ DATA LINES \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings \N pass the PCRE_NOTEMPTY option to pcre_exec() - or pcre_dfa_exec() + or pcre_dfa_exec(); if used twice, pass the + PCRE_NOTEMPTY_ATSTART option \Odd set the size of the output vector passed to pcre_exec() to dd (any number of digits) \P pass the PCRE_PARTIAL_SOFT option to pcre_exec() @@ -351,73 +353,73 @@ DATA LINES \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec() or pcre_dfa_exec() - The escapes that specify line ending sequences are literal strings, + The escapes that specify line ending sequences are literal strings, exactly as shown. No more than one newline setting should be present in any data line. - A backslash followed by anything else just escapes the anything else. - If the very last character is a backslash, it is ignored. This gives a - way of passing an empty line as data, since a real empty line termi- + A backslash followed by anything else just escapes the anything else. + If the very last character is a backslash, it is ignored. This gives a + way of passing an empty line as data, since a real empty line termi- nates the data input. - If \M is present, pcretest calls pcre_exec() several times, with dif- - ferent values in the match_limit and match_limit_recursion fields of - the pcre_extra data structure, until it finds the minimum numbers for + If \M is present, pcretest calls pcre_exec() several times, with dif- + ferent values in the match_limit and match_limit_recursion fields of + the pcre_extra data structure, until it finds the minimum numbers for each parameter that allow pcre_exec() to complete. The match_limit num- - ber is a measure of the amount of backtracking that takes place, and + ber is a measure of the amount of backtracking that takes place, and checking it out 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 + 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. The match_limit_recursion number is a measure of how - much stack (or, if PCRE is compiled with NO_RECURSE, how much heap) + much stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed to complete the match attempt. - When \O is used, the value specified may be higher or lower than the + When \O is used, the value specified may be higher or lower than the size set by the -O command line option (or defaulted to 45); \O applies only to the call of pcre_exec() for the line in which it appears. - If the /P modifier was present on the pattern, causing the POSIX wrap- - per API to be used, the only option-setting sequences that have any - effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively, + If the /P modifier was present on the pattern, causing the POSIX wrap- + per API to be used, the only option-setting sequences that have any + effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to regexec(). - The use of \x{hh...} to represent UTF-8 characters is not dependent on - the use of the /8 modifier on the pattern. It is recognized always. - There may be any number of hexadecimal digits inside the braces. The - result is from one to six bytes, encoded according to the original - UTF-8 rules of RFC 2279. This allows for values in the range 0 to - 0x7FFFFFFF. Note that not all of those are valid Unicode code points, - or indeed valid UTF-8 characters according to the later rules in RFC + The use of \x{hh...} to represent UTF-8 characters is not dependent on + the use of the /8 modifier on the pattern. It is recognized always. + There may be any number of hexadecimal digits inside the braces. The + result is from one to six bytes, encoded according to the original + UTF-8 rules of RFC 2279. This allows for values in the range 0 to + 0x7FFFFFFF. Note that not all of those are valid Unicode code points, + or indeed valid UTF-8 characters according to the later rules in RFC 3629. THE ALTERNATIVE MATCHING FUNCTION - By default, pcretest uses the standard PCRE matching function, + By default, pcretest uses the standard PCRE matching function, pcre_exec() to match each data line. From release 6.0, PCRE supports an - alternative matching function, pcre_dfa_test(), which operates in a - different way, and has some restrictions. The differences between the + alternative matching function, pcre_dfa_test(), which operates in a + different way, and has some restrictions. The differences between the two functions are described in the pcrematching documentation. - If a data line contains the \D escape sequence, or if the command line - contains the -dfa option, the alternative matching function is called. + If a data line contains the \D escape sequence, or if the command line + contains the -dfa option, the alternative matching function is called. This function finds all possible matches at a given point. If, however, - the \F escape sequence is present in the data line, it stops after the + the \F escape sequence is present in the data line, it stops after the first match is found. This is always the shortest possible match. DEFAULT OUTPUT FROM PCRETEST - This section describes the output when the normal matching function, + This section describes the output when the normal matching function, pcre_exec(), is being used. When a match succeeds, pcretest outputs the list of captured substrings - that pcre_exec() returns, starting with number 0 for the string that - matched the whole pattern. Otherwise, it outputs "No match" or "Partial - match:" followed by the partially matching substring when pcre_exec() - returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL, respectively, and - otherwise the PCRE negative error number. Here is an example of an - interactive pcretest run. + that pcre_exec() returns, starting with number 0 for the string that + matched the whole pattern. Otherwise, it outputs "No match" when the + return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par- + tially matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL. + For any other returns, it outputs the PCRE negative error number. Here + is an example of an interactive pcretest run. $ pcretest PCRE version 7.0 30-Nov-2006 @@ -429,11 +431,11 @@ DEFAULT OUTPUT FROM PCRETEST data> xyz No match - Note that unset capturing substrings that are not followed by one that - is set are not returned by pcre_exec(), and are not shown by pcretest. - 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 + Note that unset capturing substrings that are not followed by one that + is set are not returned by pcre_exec(), and are not shown by pcretest. + 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 data line. re> /(a)|(b)/ @@ -445,11 +447,11 @@ DEFAULT OUTPUT FROM PCRETEST 1: <unset> 2: b - If the strings contain any non-printing characters, they are output as - \0x escapes, or as \x{...} escapes if the /8 modifier was present on - the pattern. See below for the definition of non-printing characters. - If the pattern has the /+ modifier, the output for substring 0 is fol- - lowed by the the rest of the subject string, identified by "0+" like + If the strings contain any non-printing characters, they are output as + \0x escapes, or as \x{...} escapes if the /8 modifier was present on + the pattern. See below for the definition of non-printing characters. + If the pattern has the /+ modifier, the output for substring 0 is fol- + lowed by the the rest of the subject string, identified by "0+" like this: re> /cat/+ @@ -457,7 +459,7 @@ DEFAULT OUTPUT FROM PCRETEST 0: cat 0+ aract - If the pattern has the /g or /G modifier, the results of successive + If the pattern has the /g or /G modifier, the results of successive matching attempts are output in sequence, like this: re> /\Bi(\w\w)/g @@ -471,24 +473,24 @@ DEFAULT OUTPUT FROM PCRETEST "No match" is output only if the first match attempt fails. - If any of the sequences \C, \G, or \L are present in a data line that - is successfully matched, the substrings extracted by the convenience + If any of the sequences \C, \G, or \L are present in a data line that + 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 paren- + (that is, the return from the extraction function) is given in paren- theses after each string for \C and \G. Note that whereas patterns can be continued over several lines (a plain ">" prompt is used for continuations), data lines may not. However new- - lines can be included in data by means of the \n escape (or \r, \r\n, + lines can be included in data by means of the \n escape (or \r, \r\n, etc., depending on the newline sequence setting). OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION - When the alternative matching function, pcre_dfa_exec(), is used (by - means of the \D escape sequence or the -dfa command line option), the - output consists of a list of all the matches that start at the first + When the alternative matching function, pcre_dfa_exec(), is used (by + means of the \D escape sequence or the -dfa command line option), the + 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)/ @@ -497,8 +499,8 @@ 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). + (Using the normal matching function on this data finds only "tang".) + The longest matching string is always given first (and numbered zero). After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol- lowed by the partially matching substring. @@ -514,16 +516,16 @@ OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION 1: tan 0: tan - Since the matching function does not support substring capture, the - escape sequences that are concerned with captured substrings are not + Since the matching function does not support substring capture, the + escape sequences that are concerned with captured substrings are not relevant. RESTARTING AFTER A PARTIAL MATCH When the alternative matching function has given the PCRE_ERROR_PARTIAL - return, indicating that the subject partially matched the pattern, you - can restart the match with additional subject data by means of the \R + return, indicating that the subject partially matched the pattern, you + can restart the match with additional subject data by means of the \R escape sequence. For example: re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/ @@ -532,30 +534,30 @@ RESTARTING AFTER A PARTIAL MATCH data> n05\R\D 0: n05 - For further information about partial matching, see the pcrepartial + For further information about partial matching, see the pcrepartial documentation. CALLOUTS - If the pattern contains any callout requests, pcretest's callout func- - tion is called during matching. This works with both matching func- + If the pattern contains any callout requests, pcretest's callout func- + tion is called during matching. This works with both matching func- tions. By default, the called function displays the callout number, the - start and current positions in the text at the callout time, and the + start and current positions in the text at the callout time, and the next pattern item to be tested. For example, the output --->pqrabcdef 0 ^ ^ \d - 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 of the data, and when the next pattern item was - \d. Just one circumflex is output if the start and current positions + 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 of the data, and when the next pattern item was + \d. Just one circumflex is output if the start and current positions are the same. Callouts numbered 255 are assumed to be automatic callouts, inserted as - a result of the /C pattern modifier. In this case, instead of showing - the callout number, the offset in the pattern, preceded by a plus, is + a result of the /C pattern modifier. In this case, instead of showing + the callout number, the offset in the pattern, preceded by a plus, is output. For example: re> /\d?[A-E]\*/C @@ -567,86 +569,86 @@ CALLOUTS +10 ^ ^ 0: E* - The callout function in pcretest returns zero (carry on matching) by - default, but you can use a \C item in a data line (as described above) + The callout function in pcretest returns zero (carry on matching) by + default, but you can use a \C item in a data line (as described above) to change this. - Inserting callouts can be helpful when using pcretest to check compli- - cated regular expressions. For further information about callouts, see + Inserting callouts can be helpful when using pcretest to check compli- + cated regular expressions. For further information about callouts, see the pcrecallout documentation. NON-PRINTING CHARACTERS - When pcretest is outputting text in the compiled version of a pattern, - bytes other than 32-126 are always treated as non-printing characters + When pcretest is outputting text in the compiled version of a pattern, + bytes other than 32-126 are always treated as non-printing characters are are therefore shown as hex escapes. - When pcretest 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 /L modifier). In this case, the + When pcretest 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 /L modifier). In this case, the isprint() function to distinguish printing and non-printing characters. SAVING AND RELOADING COMPILED PATTERNS - The facilities described in this section are not available when the + The facilities described in this section are not available when the POSIX inteface to PCRE is being used, that is, when the /P pattern mod- ifier is specified. When the POSIX interface is not in use, you can cause pcretest to write - a compiled pattern to a file, by following the modifiers with > and a + a compiled pattern to a file, by following the modifiers with > and a file name. For example: /pattern/im >/some/file - See the pcreprecompile documentation for a discussion about saving and + See the pcreprecompile documentation for a discussion about saving and re-using compiled patterns. - The data that is written is binary. The first eight bytes are the - length of the compiled pattern data followed by the length of the - optional study data, each written as four bytes in big-endian order - (most significant byte first). If there is no study data (either the + The data that is written is binary. The first eight bytes are the + length of the compiled pattern data followed by the length of the + optional study data, each written as four bytes in big-endian order + (most significant byte first). If there is no study data (either the pattern was not studied, or studying did not return any data), the sec- - ond length is zero. The lengths are followed by an exact copy of the + ond length is zero. The lengths are followed by an exact copy of the compiled pattern. If there is additional study data, this follows imme- - diately after the compiled pattern. After writing the file, pcretest + diately after the compiled pattern. After writing the file, pcretest expects to read a new pattern. A saved pattern can be reloaded into pcretest by specifing < and a file - name instead of a pattern. The name of the file must not contain a < - character, as otherwise pcretest will interpret the line as a pattern + name instead of a pattern. The name of the file must not contain a < + character, as otherwise pcretest will interpret the line as a pattern delimited by < characters. For example: re> </some/file Compiled regex loaded from /some/file No study data - When the pattern has been loaded, pcretest proceeds to read data lines + When the pattern has been loaded, pcretest proceeds to read data lines in the usual way. - You can copy a file written by pcretest to a different host and reload - it there, even if the new host has opposite endianness to the one on - which the pattern was compiled. For example, you can compile on an i86 + You can copy a file written by pcretest to a different host and reload + it there, even if the new host has opposite endianness to the one on + which the pattern was compiled. For example, you can compile on an i86 machine and run on a SPARC machine. - File names for saving and reloading can be absolute or relative, but - note that the shell facility of expanding a file name that starts with + File names for saving and reloading can be absolute or relative, but + note that the shell facility of expanding a file name that starts with a tilde (~) is not available. - The ability to save and reload files in pcretest is intended for test- - ing and experimentation. It is not intended for production use because - only a single pattern can be written to a file. Furthermore, there is - no facility for supplying custom character tables for use with a - reloaded pattern. If the original pattern was compiled with custom - tables, an attempt to match a subject string using a reloaded pattern - is likely to cause pcretest to crash. Finally, if you attempt to load + The ability to save and reload files in pcretest is intended for test- + ing and experimentation. It is not intended for production use because + only a single pattern can be written to a file. Furthermore, there is + no facility for supplying custom character tables for use with a + reloaded pattern. If the original pattern was compiled with custom + tables, an attempt to match a subject string using a reloaded pattern + is likely to cause pcretest to crash. Finally, if you attempt to load a file that is not in the correct format, the result is undefined. SEE ALSO - pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d), + pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d), pcrepattern(3), pcreprecompile(3). @@ -659,5 +661,5 @@ AUTHOR REVISION - Last updated: 29 August 2009 + Last updated: 11 September 2009 Copyright (c) 1997-2009 University of Cambridge. |