| PCRETEST(1) PCRETEST(1) |
| |
| |
| NAME |
| pcretest - a program for testing Perl-compatible regular expressions. |
| |
| |
| SYNOPSIS |
| |
| pcretest [options] [input file [output file]] |
| |
| pcretest was written as a test program for the PCRE regular expression |
| library itself, but it can also be used for experimenting with regular |
| expressions. This document describes the features of the test program; |
| for details of the regular expressions themselves, see the pcrepattern |
| documentation. For details of the PCRE library function calls and their |
| options, see the pcreapi documentation. The input for pcretest is a |
| sequence of regular expression patterns and strings to be matched, as |
| described below. The output shows the result of each match. Options on |
| the command line and the patterns control PCRE options and exactly what |
| is output. |
| |
| |
| COMMAND LINE OPTIONS |
| |
| -b Behave as if each pattern has the /B (show byte code) modi- |
| fier; the internal form is output after compilation. |
| |
| -C Output the version number of the PCRE library, and all avail- |
| able information about the optional features that are |
| included, and then exit. |
| |
| -d Behave as if each pattern has the /D (debug) modifier; the |
| internal form and information about the compiled pattern is |
| output after compilation; -d is equivalent to -b -i. |
| |
| -dfa Behave as if each data line contains the \D escape sequence; |
| this causes the alternative matching function, |
| pcre_dfa_exec(), to be used instead of the standard |
| pcre_exec() function (more detail is given below). |
| |
| -help Output a brief summary these options and then exit. |
| |
| -i Behave as if each pattern has the /I modifier; information |
| about the compiled pattern is given after compilation. |
| |
| -M Behave as if each data line contains the \M escape sequence; |
| this causes PCRE to discover the minimum MATCH_LIMIT and |
| MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat- |
| edly with different limits. |
| |
| -m Output the size of each compiled pattern after it has been |
| compiled. This is equivalent to adding /M to each regular |
| expression. |
| |
| -o osize Set the number of elements in the output vector that is used |
| when calling pcre_exec() or pcre_dfa_exec() to be osize. The |
| default value is 45, which is enough for 14 capturing subex- |
| pressions for pcre_exec() or 22 different matches for |
| pcre_dfa_exec(). The vector size can be changed for individ- |
| ual matching calls by including \O in the data line (see |
| below). |
| |
| -p Behave as if each pattern has the /P modifier; the POSIX |
| wrapper API is used to call PCRE. None of the other options |
| has any effect when -p is set. |
| |
| -q Do not output the version number of pcretest at the start of |
| execution. |
| |
| -S size On Unix-like systems, set the size of the run-time stack to |
| size megabytes. |
| |
| -s or -s+ Behave as if each pattern has the /S modifier; in other |
| words, force each pattern to be studied. If -s+ is used, the |
| PCRE_STUDY_JIT_COMPILE flag is passed to pcre_study(), caus- |
| ing just-in-time optimization to be set up if it is avail- |
| able. If the /I or /D option is present on a pattern |
| (requesting output about the compiled pattern), information |
| about the result of studying is not included when studying is |
| caused only by -s and neither -i nor -d is present on the |
| command line. This behaviour means that the output from tests |
| that are run with and without -s should be identical, except |
| when options that output information about the actual running |
| of a match are set. The -M, -t, and -tm options, which give |
| information about resources used, are likely to produce dif- |
| ferent output with and without -s. Output may also differ if |
| the /C option is present on an individual pattern. This uses |
| callouts to trace the the matching process, and this may be |
| different between studied and non-studied patterns. If the |
| pattern contains (*MARK) items there may also be differences, |
| for the same reason. The -s command line option can be over- |
| ridden for specific patterns that should never be studied |
| (see the /S pattern modifier below). |
| |
| -t Run each compile, study, and match many times with a timer, |
| and output resulting time per compile or match (in millisec- |
| onds). Do not set -m with -t, because you will then get the |
| size output a zillion times, and the timing will be dis- |
| torted. You can control the number of iterations that are |
| used for timing by following -t with a number (as a separate |
| item on the command line). For example, "-t 1000" would iter- |
| ate 1000 times. The default is to iterate 500000 times. |
| |
| -tm This is like -t except that it times only the matching phase, |
| not the compile or study phases. |
| |
| |
| DESCRIPTION |
| |
| If pcretest is given two filename arguments, it reads from the first |
| and writes to the second. If it is given only one filename argument, it |
| reads from that file and writes to stdout. Otherwise, it reads from |
| stdin and writes to stdout, and prompts for each line of input, using |
| "re>" to prompt for regular expressions, and "data>" to prompt for data |
| lines. |
| |
| When pcretest is built, a configuration option can specify that it |
| should be linked with the libreadline library. When this is done, if |
| the input is from a terminal, it is read using the readline() function. |
| This provides line-editing and history facilities. The output from the |
| -help option states whether or not readline() will be used. |
| |
| The program handles any number of sets of input on a single input file. |
| Each set starts with a regular expression, and continues with any num- |
| ber of data lines to be matched against the pattern. |
| |
| Each data line is matched separately and independently. If you want to |
| do multi-line matches, you have to use the \n escape sequence (or \r or |
| \r\n, etc., depending on the newline setting) in a single line of input |
| to encode the newline sequences. There is no limit on the length of |
| data lines; the input buffer is automatically extended if it is too |
| small. |
| |
| An empty line signals the end of the data lines, at which point a new |
| regular expression is read. The regular expressions are given enclosed |
| in any non-alphanumeric delimiters other than backslash, for example: |
| |
| /(a|bc)x+yz/ |
| |
| White space before the initial delimiter is ignored. A regular expres- |
| sion may be continued over several input lines, in which case the new- |
| line characters are included within it. It is possible to include the |
| delimiter within the pattern by escaping it, for example |
| |
| /abc\/def/ |
| |
| If you do so, the escape and the delimiter form part of the pattern, |
| but since delimiters are always non-alphanumeric, this does not affect |
| its interpretation. If the terminating delimiter is immediately fol- |
| lowed by a backslash, for example, |
| |
| /abc/\ |
| |
| then a backslash is added to the end of the pattern. This is done to |
| provide a way of testing the error condition that arises if a pattern |
| finishes with a backslash, because |
| |
| /abc\/ |
| |
| is interpreted as the first line of a pattern that starts with "abc/", |
| causing pcretest to read the next line as a continuation of the regular |
| expression. |
| |
| |
| PATTERN MODIFIERS |
| |
| A pattern may be followed by any number of modifiers, which are mostly |
| single characters. Following Perl usage, these are referred to below |
| as, for example, "the /i modifier", even though the delimiter of the |
| pattern need not always be a slash, and no slash is used when writing |
| modifiers. White space may appear between the final pattern delimiter |
| and the first modifier, and between the modifiers themselves. |
| |
| The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE, |
| PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com- |
| pile() is called. These four modifier letters have the same effect as |
| they do in Perl. For example: |
| |
| /caseless/i |
| |
| The following table shows additional modifiers for setting PCRE com- |
| pile-time options that do not correspond to anything in Perl: |
| |
| /8 PCRE_UTF8 |
| /? PCRE_NO_UTF8_CHECK |
| /A PCRE_ANCHORED |
| /C PCRE_AUTO_CALLOUT |
| /E PCRE_DOLLAR_ENDONLY |
| /f PCRE_FIRSTLINE |
| /J PCRE_DUPNAMES |
| /N PCRE_NO_AUTO_CAPTURE |
| /U PCRE_UNGREEDY |
| /W PCRE_UCP |
| /X PCRE_EXTRA |
| /Y PCRE_NO_START_OPTIMIZE |
| /<JS> PCRE_JAVASCRIPT_COMPAT |
| /<cr> PCRE_NEWLINE_CR |
| /<lf> PCRE_NEWLINE_LF |
| /<crlf> PCRE_NEWLINE_CRLF |
| /<anycrlf> PCRE_NEWLINE_ANYCRLF |
| /<any> PCRE_NEWLINE_ANY |
| /<bsr_anycrlf> PCRE_BSR_ANYCRLF |
| /<bsr_unicode> PCRE_BSR_UNICODE |
| |
| The modifiers that are enclosed in angle brackets are literal strings |
| as shown, including the angle brackets, but the letters within can be |
| in either case. This example sets multiline matching with CRLF as the |
| line ending sequence: |
| |
| /^abc/m<CRLF> |
| |
| As well as turning on the PCRE_UTF8 option, the /8 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. Full details of |
| the PCRE options are given in the pcreapi documentation. |
| |
| Finding all matches in a string |
| |
| Searching for all possible matches within each subject string can be |
| requested by the /g or /G modifier. After finding a match, PCRE is |
| called again to search the remainder of the subject string. The differ- |
| ence between /g and /G is that the former uses the startoffset argument |
| to pcre_exec() to start searching at a new point within the entire |
| string (which is in effect what Perl does), whereas the latter passes |
| over a shortened substring. This makes a difference to the matching |
| process if the pattern begins with a lookbehind assertion (including \b |
| 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_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, and the normal match is retried. This imitates the way |
| Perl handles such cases when using the /g modifier or the split() func- |
| tion. 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 is used. |
| |
| 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 |
| subject contains multiple copies of the same substring. If the + modi- |
| fier appears twice, the same action is taken for captured substrings. |
| In each case the remainder is output on the following line with a plus |
| character following the capture number. Note that this modifier must |
| not immediately follow the /S modifier because /S+ has another meaning. |
| |
| The /= modifier requests that the values of all potential captured |
| parentheses be output after a match by pcre_exec(). By default, only |
| those up to the highest one actually used in the match are output (cor- |
| responding to the return code from pcre_exec()). Values in the offsets |
| vector corresponding to higher numbers should be set to -1, and these |
| are output as "<unset>". This modifier gives a way of checking that |
| this is happening. |
| |
| 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 /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 |
| 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 |
| section about saving and reloading compiled patterns below. |
| |
| 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 /K modifier requests pcretest to show names from backtracking con- |
| trol verbs that are returned from calls to pcre_exec(). It causes |
| pcretest to create a pcre_extra block if one has not already been cre- |
| ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and |
| the mark field within it, every time that pcre_exec() is called. If the |
| variable that the mark field points to is non-NULL for a match, non- |
| match, or partial match, pcretest prints the string to which it points. |
| For a match, this is shown on a line by itself, tagged with "MK:". For |
| a non-match it is added to the message. |
| |
| 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 (or /T) modifier, NULL is passed as |
| the tables pointer; that is, /L applies only to the expression on which |
| it appears. |
| |
| The /M modifier causes the size of memory block used to hold the com- |
| piled pattern to be output. This does not include the size of the pcre |
| block; it is just the actual compiled data. If the pattern is success- |
| fully studied with the PCRE_STUDY_JIT_COMPILE option, the size of the |
| JIT compiled code is also output. |
| |
| If the /S modifier appears once, it causes pcre_study() to be called |
| after the expression has been compiled, and the results used when the |
| expression is matched. If /S appears twice, it suppresses studying, |
| even if it was requested externally by the -s command line option. This |
| makes it possible to specify that certain patterns are always studied, |
| and others are never studied, independently of -s. This feature is used |
| in the test files in a few cases where the output is different when the |
| pattern is studied. |
| |
| If the /S modifier is immediately followed by a + character, the call |
| to pcre_study() is made with the PCRE_STUDY_JIT_COMPILE option, |
| requesting just-in-time optimization support if it is available. Note |
| that there is also a /+ modifier; it must not be given immediately |
| after /S because this will be misinterpreted. If JIT studying is suc- |
| cessful, it will automatically be used when pcre_exec() is run, except |
| when incompatible run-time options are specified. These include the |
| partial matching options; a complete list is given in the pcrejit docu- |
| mentation. See also the \J escape sequence below for a way of setting |
| the size of the JIT stack. |
| |
| The /T modifier must be followed by a single digit. It causes a spe- |
| cific set of built-in character tables to be passed to pcre_compile(). |
| It is used in the standard PCRE tests to check behaviour with different |
| character tables. The digit specifies the tables as follows: |
| |
| 0 the default ASCII tables, as distributed in |
| pcre_chartables.c.dist |
| 1 a set of tables defining ISO 8859 characters |
| |
| In table 1, some characters whose codes are greater than 128 are iden- |
| tified as letters, digits, spaces, etc. |
| |
| Using the POSIX wrapper API |
| |
| The /P modifier causes pcretest to call PCRE via the POSIX wrapper API |
| rather than its native API. When /P is set, the following modifiers set |
| options for the regcomp() function: |
| |
| /i REG_ICASE |
| /m REG_NEWLINE |
| /N REG_NOSUB |
| /s REG_DOTALL ) |
| /U REG_UNGREEDY ) These options are not part of |
| /W REG_UCP ) the POSIX standard |
| /8 REG_UTF8 ) |
| |
| The /+ modifier works as described above. All other modifiers are |
| ignored. |
| |
| |
| DATA LINES |
| |
| Before each data line is passed to pcre_exec(), leading and trailing |
| white space 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) |
| \b backspace (\x08) |
| \e escape (\x27) |
| \f form feed (\x0c) |
| \n newline (\x0a) |
| \qdd set the PCRE_MATCH_LIMIT limit to dd |
| (any number of digits) |
| \r carriage return (\x0d) |
| \t tab (\x09) |
| \v vertical tab (\x0b) |
| \nnn octal character (up to 3 octal digits) |
| always a byte unless > 255 in UTF-8 mode |
| \xhh hexadecimal byte (up to 2 hex digits) |
| \x{hh...} hexadecimal character, any number of digits |
| in UTF-8 mode |
| \A pass the PCRE_ANCHORED option to pcre_exec() |
| or pcre_dfa_exec() |
| \B pass the PCRE_NOTBOL option to pcre_exec() |
| or pcre_dfa_exec() |
| \Cdd call pcre_copy_substring() for substring dd |
| after a successful match (number less than 32) |
| \Cname call pcre_copy_named_substring() for substring |
| "name" after a successful match (name termin- |
| ated by next non alphanumeric character) |
| \C+ show the current captured substrings at callout |
| time |
| \C- do not supply a callout function |
| \C!n return 1 instead of 0 when callout number n is |
| reached |
| \C!n!m return 1 instead of 0 when callout number n is |
| reached for the nth time |
| \C*n pass the number n (may be negative) as callout |
| data; this is used as the callout return value |
| \D use the pcre_dfa_exec() match function |
| \F only shortest match for pcre_dfa_exec() |
| \Gdd call pcre_get_substring() for substring dd |
| after a successful match (number less than 32) |
| \Gname call pcre_get_named_substring() for substring |
| "name" after a successful match (name termin- |
| ated by next non-alphanumeric character) |
| \Jdd set up a JIT stack of dd kilobytes maximum (any |
| number of digits) |
| \L call pcre_get_substringlist() after a |
| successful match |
| \M discover the minimum MATCH_LIMIT and |
| MATCH_LIMIT_RECURSION settings |
| \N pass the PCRE_NOTEMPTY option to pcre_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() |
| or pcre_dfa_exec(); if used twice, pass the |
| PCRE_PARTIAL_HARD option |
| \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd |
| (any number of digits) |
| \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec() |
| \S output details of memory get/free calls during matching |
| \Y pass the PCRE_NO_START_OPTIMIZE option to pcre_exec() |
| or pcre_dfa_exec() |
| \Z pass the PCRE_NOTEOL option to pcre_exec() |
| or pcre_dfa_exec() |
| \? pass the PCRE_NO_UTF8_CHECK option to |
| pcre_exec() or pcre_dfa_exec() |
| \>dd start the match at offset dd (optional "-"; then |
| any number of digits); this sets the startoffset |
| argument for pcre_exec() or pcre_dfa_exec() |
| \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec() |
| or pcre_dfa_exec() |
| \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec() |
| or pcre_dfa_exec() |
| \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec() |
| or pcre_dfa_exec() |
| \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec() |
| or pcre_dfa_exec() |
| \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec() |
| or pcre_dfa_exec() |
| |
| Note that \xhh always specifies one byte, even in UTF-8 mode; this |
| makes it possible to construct invalid UTF-8 sequences for testing pur- |
| poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in |
| UTF-8 mode, generating more than one byte if the value is greater than |
| 127. When not in UTF-8 mode, it generates one byte for values less than |
| 256, and causes an error for greater values. |
| |
| 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- |
| nates the data input. |
| |
| The \J escape provides a way of setting the maximum stack size that is |
| used by the just-in-time optimization code. It is ignored if JIT opti- |
| mization is not being used. Providing a stack that is larger than the |
| default 32K is necessary only for very complicated patterns. |
| |
| 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 without error. |
| Because this is testing a specific feature of the normal interpretive |
| pcre_exec() execution, the use of any JIT optimization that might have |
| been set up by the /S+ qualifier of -s+ option is disabled. |
| |
| The match_limit number 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 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) memory is needed to complete the match |
| attempt. |
| |
| 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, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, 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 |
| 3629. |
| |
| |
| THE ALTERNATIVE 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 |
| 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. |
| 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 |
| 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, |
| 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" when the |
| return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par- |
| tially matching substring when pcre_exec() returns PCRE_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, pcretest outputs the PCRE negative error number and a short |
| descriptive phrase. If the error is a failed UTF-8 string check, the |
| byte offset of the start of the failing character and the reason code |
| are also output, provided that the size of the output vector is at |
| least two. Here is an example of an interactive pcretest run. |
| |
| $ pcretest |
| PCRE version 8.13 2011-04-30 |
| |
| re> /^abc(\d+)/ |
| data> abc123 |
| 0: abc123 |
| 1: 123 |
| data> xyz |
| No match |
| |
| 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 fol- |
| lowing 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)/ |
| data> a |
| 0: a |
| 1: a |
| data> b |
| 0: b |
| 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 |
| this: |
| |
| re> /cat/+ |
| data> cataract |
| 0: cat |
| 0+ aract |
| |
| 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 |
| data> Mississippi |
| 0: iss |
| 1: ss |
| 0: iss |
| 1: ss |
| 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 \>4 is |
| past the end of the subject string): |
| |
| re> /xyz/ |
| data> xyz\>4 |
| Error -24 (bad offset value) |
| |
| 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- |
| 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, |
| 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 |
| point in the subject where there is at least one match. For example: |
| |
| re> /(tang|tangerine|tan)/ |
| data> yellow tangerine\D |
| 0: tangerine |
| 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 PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol- |
| lowed 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, \K, \b, or \B was involved.) |
| |
| If /g is present on the pattern, the search for further matches resumes |
| at the end of the longest match. For example: |
| |
| re> /(tang|tangerine|tan)/g |
| data> yellow tangerine and tangy sultana\D |
| 0: tangerine |
| 1: tang |
| 2: tan |
| 0: tang |
| 1: tan |
| 0: tan |
| |
| 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 |
| escape sequence. For example: |
| |
| re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/ |
| data> 23ja\P\D |
| Partial match: 23ja |
| data> n05\R\D |
| 0: n05 |
| |
| 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- |
| tions. By default, the called function displays the callout number, 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 |
| 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 |
| output. For example: |
| |
| re> /\d?[A-E]\*/C |
| data> E* |
| --->E* |
| +0 ^ \d? |
| +3 ^ [A-E] |
| +8 ^^ \* |
| +10 ^ ^ |
| 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 |
| example: |
| |
| re> /a(*MARK:X)bc/C |
| data> abc |
| --->abc |
| +0 ^ a |
| +1 ^^ (*MARK:X) |
| +10 ^^ b |
| Latest Mark: X |
| +11 ^ ^ c |
| +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 |
| output. |
| |
| 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 and other parameters of the callout. |
| |
| 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 |
| 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 |
| 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 |
| POSIX interface to PCRE is being used, that is, when the /P pattern |
| modifier 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 |
| file name. For example: |
| |
| /pattern/im >/some/file |
| |
| See the pcreprecompile documentation for a discussion about saving and |
| re-using compiled patterns. Note that if the pattern was successfully |
| studied with JIT optimization, the JIT data cannot be saved. |
| |
| 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 |
| compiled pattern. If there is additional study data, this (excluding |
| any JIT data) follows immediately after the compiled pattern. After |
| writing the file, pcretest expects to read a new pattern. |
| |
| A saved pattern can be reloaded into pcretest by specifying < 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 |
| delimited by < characters. For example: |
| |
| re> </some/file |
| Compiled pattern loaded from /some/file |
| No study data |
| |
| If the pattern was previously studied with the JIT optimization, the |
| JIT information cannot be saved and restored, and so is lost. 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 |
| 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 |
| 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 |
| a file that is not in the correct format, the result is undefined. |
| |
| |
| SEE ALSO |
| |
| pcre(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematching(3), pcrepar- |
| tial(d), pcrepattern(3), pcreprecompile(3). |
| |
| |
| AUTHOR |
| |
| Philip Hazel |
| University Computing Service |
| Cambridge CB2 3QH, England. |
| |
| |
| REVISION |
| |
| Last updated: 02 December 2011 |
| Copyright (c) 1997-2011 University of Cambridge. |