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The pcretest program |
PCRETEST(1) PCRETEST(1) |
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This program is intended for testing PCRE, but it can also be used for |
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experimenting with regular expressions. |
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If it is given two filename arguments, it reads from the first and writes to |
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the second. If it is given only one filename argument, it reads from that file |
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and writes to stdout. Otherwise, it reads from stdin and writes to stdout, and |
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prompts for each line of input, using "re>" to prompt for regular expressions, |
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and "data>" to prompt for data lines. |
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The program handles any number of sets of input on a single input file. Each |
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set starts with a regular expression, and continues with any number of data |
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lines to be matched against the pattern. An empty line signals the end of the |
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data lines, at which point a new regular expression is read. The regular |
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expressions are given enclosed in any non-alphameric delimiters other than |
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backslash, for example |
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/(a|bc)x+yz/ |
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White space before the initial delimiter is ignored. A regular expression may |
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be continued over several input lines, in which case the newline characters are |
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included within it. See the test input files in the testdata directory for many |
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examples. It is possible to include the delimiter within the pattern by |
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escaping it, for example |
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/abc\/def/ |
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If you do so, the escape and the delimiter form part of the pattern, but since |
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delimiters are always non-alphameric, this does not affect its interpretation. |
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If the terminating delimiter is immediately followed by a backslash, for |
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example, |
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/abc/\ |
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then a backslash is added to the end of the pattern. This is done to provide a |
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way of testing the error condition that arises if a pattern finishes with a |
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backslash, because |
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/abc\/ |
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is interpreted as the first line of a pattern that starts with "abc/", causing |
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pcretest to read the next line as a continuation of the regular expression. |
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The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS, |
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PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. For |
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example: |
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/caseless/i |
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These modifier letters have the same effect as they do in Perl. There are |
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others which set PCRE options that do not correspond to anything in Perl: /A, |
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/E, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively. |
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Searching for all possible matches within each subject string can be requested |
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by the /g or /G modifier. After finding a match, PCRE is called again to search |
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the remainder of the subject string. The difference between /g and /G is that |
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the former uses the startoffset argument to pcre_exec() to start searching at |
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a new point within the entire string (which is in effect what Perl does), |
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whereas the latter passes over a shortened substring. This makes a difference |
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to the matching process if the pattern begins with a lookbehind assertion |
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(including \b or \B). |
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If any call to pcre_exec() in a /g or /G sequence matches an empty string, the |
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next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED flags set in order |
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to search for another, non-empty, match at the same point. If this second match |
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fails, the start offset is advanced by one, and the normal match is retried. |
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This imitates the way Perl handles such cases when using the /g modifier or the |
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split() function. |
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There are a number of other modifiers for controlling the way pcretest |
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operates. |
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The /+ modifier requests that as well as outputting the substring that matched |
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the entire pattern, pcretest should in addition output the remainder of the |
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subject string. This is useful for tests where the subject contains multiple |
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copies of the same substring. |
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The /L modifier must be followed directly by the name of a locale, for example, |
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/pattern/Lfr |
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For this reason, it must be the last modifier letter. The given locale is set, |
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pcre_maketables() is called to build a set of character tables for the locale, |
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and this is then passed to pcre_compile() when compiling the regular |
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expression. Without an /L modifier, NULL is passed as the tables pointer; that |
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is, /L applies only to the expression on which it appears. |
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The /I modifier requests that pcretest output information about the compiled |
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expression (whether it is anchored, has a fixed first character, and so on). It |
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does this by calling pcre_fullinfo() after compiling an expression, and |
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outputting the information it gets back. If the pattern is studied, the results |
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of that are also output. |
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The /D modifier is a PCRE debugging feature, which also assumes /I. It causes |
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the internal form of compiled regular expressions to be output after |
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compilation. |
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The /S modifier causes pcre_study() to be called after the expression has been |
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compiled, and the results used when the expression is matched. |
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The /M modifier causes the size of memory block used to hold the compiled |
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pattern to be output. |
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Finally, the /P modifier causes pcretest to call PCRE via the POSIX wrapper API |
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rather than its native API. When this is done, all other modifiers except /i, |
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/m, and /+ are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is |
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set if /m is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always, |
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and PCRE_DOTALL unless REG_NEWLINE is set. |
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Before each data line is passed to pcre_exec(), leading and trailing whitespace |
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is removed, and it is then scanned for \ escapes. The following are recognized: |
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\a alarm (= BEL) |
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\b backspace |
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\e escape |
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\f formfeed |
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\n newline |
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\r carriage return |
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\t tab |
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\v vertical tab |
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\nnn octal character (up to 3 octal digits) |
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\xhh hexadecimal character (up to 2 hex digits) |
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\A pass the PCRE_ANCHORED option to pcre_exec() |
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\B pass the PCRE_NOTBOL option to pcre_exec() |
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\Cdd call pcre_copy_substring() for substring dd after a successful match |
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(any decimal number less than 32) |
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\Gdd call pcre_get_substring() for substring dd after a successful match |
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(any decimal number less than 32) |
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\L call pcre_get_substringlist() after a successful match |
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\N pass the PCRE_NOTEMPTY option to pcre_exec() |
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\Odd set the size of the output vector passed to pcre_exec() to dd |
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(any number of decimal digits) |
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\Z pass the PCRE_NOTEOL option to pcre_exec() |
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A backslash followed by anything else just escapes the anything else. If the |
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very last character is a backslash, it is ignored. This gives a way of passing |
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an empty line as data, since a real empty line terminates the data input. |
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If /P was present on the regex, causing the POSIX wrapper API to be used, only |
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\B, and \Z have any effect, causing REG_NOTBOL and REG_NOTEOL to be passed to |
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regexec() respectively. |
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When a match succeeds, pcretest outputs the list of captured substrings that |
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pcre_exec() returns, starting with number 0 for the string that matched the |
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whole pattern. Here is an example of an interactive pcretest run. |
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$ pcretest |
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PCRE version 2.06 08-Jun-1999 |
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re> /^abc(\d+)/ |
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data> abc123 |
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0: abc123 |
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1: 123 |
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data> xyz |
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No match |
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If the strings contain any non-printing characters, they are output as \0x |
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escapes. If the pattern has the /+ modifier, then the output for substring 0 is |
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followed by the the rest of the subject string, identified by "0+" like this: |
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re> /cat/+ |
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data> cataract |
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0: cat |
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0+ aract |
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If the pattern has the /g or /G modifier, the results of successive matching |
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attempts are output in sequence, like this: |
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re> /\Bi(\w\w)/g |
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data> Mississippi |
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0: iss |
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1: ss |
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0: iss |
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1: ss |
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0: ipp |
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1: pp |
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"No match" is output only if the first match attempt fails. |
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If any of \C, \G, or \L are present in a data line that is successfully |
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matched, the substrings extracted by the convenience functions are output with |
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C, G, or L after the string number instead of a colon. This is in addition to |
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the normal full list. The string length (that is, the return from the |
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extraction function) is given in parentheses after each string for \C and \G. |
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Note that while patterns can be continued over several lines (a plain ">" |
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prompt is used for continuations), data lines may not. However newlines can be |
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included in data by means of the \n escape. |
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If the -p option is given to pcretest, it is equivalent to adding /P to each |
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regular expression: the POSIX wrapper API is used to call PCRE. None of the |
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following flags has any effect in this case. |
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If the option -d is given to pcretest, it is equivalent to adding /D to each |
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regular expression: the internal form is output after compilation. |
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If the option -i is given to pcretest, it is equivalent to adding /I to each |
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regular expression: information about the compiled pattern is given after |
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compilation. |
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If the option -m is given to pcretest, it outputs the size of each compiled |
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pattern after it has been compiled. It is equivalent to adding /M to each |
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regular expression. For compatibility with earlier versions of pcretest, -s is |
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a synonym for -m. |
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If the -t option is given, each compile, study, and match is run 20000 times |
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while being timed, and the resulting time per compile or match is output in |
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milliseconds. Do not set -t with -s, because you will then get the size output |
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20000 times and the timing will be distorted. If you want to change the number |
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of repetitions used for timing, edit the definition of LOOPREPEAT at the top of |
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pcretest.c |
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Philip Hazel <ph10@cam.ac.uk> |
NAME |
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January 2000 |
pcretest - a program for testing Perl-compatible regular expressions. |
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SYNOPSIS |
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pcretest [-d] [-i] [-m] [-o osize] [-p] [-t] [source] [destination] |
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pcretest was written as a test program for the PCRE regular expression |
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library itself, but it can also be used for experimenting with regular |
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expressions. This document describes the features of the test program; |
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for details of the regular expressions themselves, see the pcrepattern |
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documentation. For details of PCRE and its options, see the pcreapi |
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documentation. |
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OPTIONS |
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-C Output the version number of the PCRE library, and all avail- |
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able information about the optional features that are |
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included, and then exit. |
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-d Behave as if each regex had the /D modifier (see below); the |
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internal form is output after compilation. |
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-i Behave as if each regex had the /I modifier; information |
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about the compiled pattern is given after compilation. |
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-m Output the size of each compiled pattern after it has been |
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compiled. This is equivalent to adding /M to each regular |
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expression. For compatibility with earlier versions of |
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pcretest, -s is a synonym for -m. |
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-o osize Set the number of elements in the output vector that is used |
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when calling PCRE to be osize. The default value is 45, which |
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is enough for 14 capturing subexpressions. The vector size |
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can be changed for individual matching calls by including \O |
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in the data line (see below). |
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-p Behave as if each regex has /P modifier; the POSIX wrapper |
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API is used to call PCRE. None of the other options has any |
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effect when -p is set. |
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-t Run each compile, study, and match many times with a timer, |
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and output resulting time per compile or match (in millisec- |
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onds). Do not set -t with -m, because you will then get the |
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size output 20000 times and the timing will be distorted. |
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DESCRIPTION |
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If pcretest is given two filename arguments, it reads from the first |
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and writes to the second. If it is given only one filename argument, it |
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reads from that file and writes to stdout. Otherwise, it reads from |
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stdin and writes to stdout, and prompts for each line of input, using |
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"re>" to prompt for regular expressions, and "data>" to prompt for data |
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lines. |
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The program handles any number of sets of input on a single input file. |
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Each set starts with a regular expression, and continues with any num- |
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ber of data lines to be matched against the pattern. |
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Each line is matched separately and independently. If you want to do |
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multiple-line matches, you have to use the \n escape sequence in a sin- |
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gle line of input to encode the newline characters. The maximum length |
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of data line is 30,000 characters. |
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An empty line signals the end of the data lines, at which point a new |
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regular expression is read. The regular expressions are given enclosed |
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in any non-alphameric delimiters other than backslash, for example |
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/(a|bc)x+yz/ |
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White space before the initial delimiter is ignored. A regular expres- |
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sion may be continued over several input lines, in which case the new- |
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line characters are included within it. It is possible to include the |
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delimiter within the pattern by escaping it, for example |
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/abc\/def/ |
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If you do so, the escape and the delimiter form part of the pattern, |
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but since delimiters are always non-alphameric, this does not affect |
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its interpretation. If the terminating delimiter is immediately fol- |
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lowed by a backslash, for example, |
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/abc/\ |
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then a backslash is added to the end of the pattern. This is done to |
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provide a way of testing the error condition that arises if a pattern |
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finishes with a backslash, because |
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/abc\/ |
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is interpreted as the first line of a pattern that starts with "abc/", |
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causing pcretest to read the next line as a continuation of the regular |
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expression. |
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PATTERN MODIFIERS |
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The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS, |
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PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. |
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For example: |
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/caseless/i |
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These modifier letters have the same effect as they do in Perl. There |
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are others that set PCRE options that do not correspond to anything in |
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Perl: /A, /E, /N, /U, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, |
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PCRE_NO_AUTO_CAPTURE, PCRE_UNGREEDY, and PCRE_EXTRA respectively. |
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Searching for all possible matches within each subject string can be |
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requested by the /g or /G modifier. After finding a match, PCRE is |
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called again to search the remainder of the subject string. The differ- |
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ence between /g and /G is that the former uses the startoffset argument |
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to pcre_exec() to start searching at a new point within the entire |
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string (which is in effect what Perl does), whereas the latter passes |
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over a shortened substring. This makes a difference to the matching |
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process if the pattern begins with a lookbehind assertion (including \b |
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or \B). |
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If any call to pcre_exec() in a /g or /G sequence matches an empty |
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string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED |
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flags set in order to search for another, non-empty, match at the same |
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point. If this second match fails, the start offset is advanced by |
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one, and the normal match is retried. This imitates the way Perl han- |
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dles such cases when using the /g modifier or the split() function. |
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There are a number of other modifiers for controlling the way pcretest |
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operates. |
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The /+ modifier requests that as well as outputting the substring that |
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matched the entire pattern, pcretest should in addition output the |
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remainder of the subject string. This is useful for tests where the |
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subject contains multiple copies of the same substring. |
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The /L modifier must be followed directly by the name of a locale, for |
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example, |
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/pattern/Lfr |
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For this reason, it must be the last modifier letter. The given locale |
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is set, pcre_maketables() is called to build a set of character tables |
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for the locale, and this is then passed to pcre_compile() when compil- |
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ing the regular expression. Without an /L modifier, NULL is passed as |
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the tables pointer; that is, /L applies only to the expression on which |
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it appears. |
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The /I modifier requests that pcretest output information about the |
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compiled expression (whether it is anchored, has a fixed first charac- |
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ter, and so on). It does this by calling pcre_fullinfo() after compil- |
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ing an expression, and outputting the information it gets back. If the |
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pattern is studied, the results of that are also output. |
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The /D modifier is a PCRE debugging feature, which also assumes /I. It |
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causes the internal form of compiled regular expressions to be output |
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after compilation. If the pattern was studied, the information returned |
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is also output. |
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The /S modifier causes pcre_study() to be called after the expression |
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has been compiled, and the results used when the expression is matched. |
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The /M modifier causes the size of memory block used to hold the com- |
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piled pattern to be output. |
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The /P modifier causes pcretest to call PCRE via the POSIX wrapper API |
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rather than its native API. When this is done, all other modifiers |
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except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present, |
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and REG_NEWLINE is set if /m is present. The wrapper functions force |
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PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set. |
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The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option |
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set. This turns on support for UTF-8 character handling in PCRE, pro- |
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vided that it was compiled with this support enabled. This modifier |
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also causes any non-printing characters in output strings to be printed |
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using the \x{hh...} notation if they are valid UTF-8 sequences. |
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If the /? modifier is used with /8, it causes pcretest to call |
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pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the |
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checking of the string for UTF-8 validity. |
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CALLOUTS |
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If the pattern contains any callout requests, pcretest's callout func- |
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tion will be called. By default, it displays the callout number, and |
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the start and current positions in the text at the callout time. For |
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example, the output |
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--->pqrabcdef |
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0 ^ ^ |
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indicates that callout number 0 occurred for a match attempt starting |
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at the fourth character of the subject string, when the pointer was at |
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the seventh character. The callout function returns zero (carry on |
| 199 |
|
matching) by default. |
| 200 |
|
|
| 201 |
|
Inserting callouts may be helpful when using pcretest to check compli- |
| 202 |
|
cated regular expressions. For further information about callouts, see |
| 203 |
|
the pcrecallout documentation. |
| 204 |
|
|
| 205 |
|
For testing the PCRE library, additional control of callout behaviour |
| 206 |
|
is available via escape sequences in the data, as described in the fol- |
| 207 |
|
lowing section. In particular, it is possible to pass in a number as |
| 208 |
|
callout data (the default is zero). If the callout function receives a |
| 209 |
|
non-zero number, it returns that value instead of zero. |
| 210 |
|
|
| 211 |
|
|
| 212 |
|
DATA LINES |
| 213 |
|
|
| 214 |
|
Before each data line is passed to pcre_exec(), leading and trailing |
| 215 |
|
whitespace is removed, and it is then scanned for \ escapes. Some of |
| 216 |
|
these are pretty esoteric features, intended for checking out some of |
| 217 |
|
the more complicated features of PCRE. If you are just testing "ordi- |
| 218 |
|
nary" regular expressions, you probably don't need any of these. The |
| 219 |
|
following escapes are recognized: |
| 220 |
|
|
| 221 |
|
\a alarm (= BEL) |
| 222 |
|
\b backspace |
| 223 |
|
\e escape |
| 224 |
|
\f formfeed |
| 225 |
|
\n newline |
| 226 |
|
\r carriage return |
| 227 |
|
\t tab |
| 228 |
|
\v vertical tab |
| 229 |
|
\nnn octal character (up to 3 octal digits) |
| 230 |
|
\xhh hexadecimal character (up to 2 hex digits) |
| 231 |
|
\x{hh...} hexadecimal character, any number of digits |
| 232 |
|
in UTF-8 mode |
| 233 |
|
\A pass the PCRE_ANCHORED option to pcre_exec() |
| 234 |
|
\B pass the PCRE_NOTBOL option to pcre_exec() |
| 235 |
|
\Cdd call pcre_copy_substring() for substring dd |
| 236 |
|
after a successful match (any decimal number |
| 237 |
|
less than 32) |
| 238 |
|
\Cname call pcre_copy_named_substring() for substring |
| 239 |
|
"name" after a successful match (name termin- |
| 240 |
|
ated by next non alphanumeric character) |
| 241 |
|
\C+ show the current captured substrings at callout |
| 242 |
|
time |
| 243 |
|
\C- do not supply a callout function |
| 244 |
|
\C!n return 1 instead of 0 when callout number n is |
| 245 |
|
reached |
| 246 |
|
\C!n!m return 1 instead of 0 when callout number n is |
| 247 |
|
reached for the nth time |
| 248 |
|
\C*n pass the number n (may be negative) as callout |
| 249 |
|
data |
| 250 |
|
\Gdd call pcre_get_substring() for substring dd |
| 251 |
|
after a successful match (any decimal number |
| 252 |
|
less than 32) |
| 253 |
|
\Gname call pcre_get_named_substring() for substring |
| 254 |
|
"name" after a successful match (name termin- |
| 255 |
|
ated by next non-alphanumeric character) |
| 256 |
|
\L call pcre_get_substringlist() after a |
| 257 |
|
successful match |
| 258 |
|
\M discover the minimum MATCH_LIMIT setting |
| 259 |
|
\N pass the PCRE_NOTEMPTY option to pcre_exec() |
| 260 |
|
\Odd set the size of the output vector passed to |
| 261 |
|
pcre_exec() to dd (any number of decimal |
| 262 |
|
digits) |
| 263 |
|
\S output details of memory get/free calls during matching |
| 264 |
|
\Z pass the PCRE_NOTEOL option to pcre_exec() |
| 265 |
|
\? pass the PCRE_NO_UTF8_CHECK option to |
| 266 |
|
pcre_exec() |
| 267 |
|
|
| 268 |
|
If \M is present, pcretest calls pcre_exec() several times, with dif- |
| 269 |
|
ferent values in the match_limit field of the pcre_extra data struc- |
| 270 |
|
ture, until it finds the minimum number that is needed for pcre_exec() |
| 271 |
|
to complete. This number is a measure of the amount of recursion and |
| 272 |
|
backtracking that takes place, and checking it out can be instructive. |
| 273 |
|
For most simple matches, the number is quite small, but for patterns |
| 274 |
|
with very large numbers of matching possibilities, it can become large |
| 275 |
|
very quickly with increasing length of subject string. |
| 276 |
|
|
| 277 |
|
When \O is used, it may be higher or lower than the size set by the -O |
| 278 |
|
option (or defaulted to 45); \O applies only to the call of pcre_exec() |
| 279 |
|
for the line in which it appears. |
| 280 |
|
|
| 281 |
|
A backslash followed by anything else just escapes the anything else. |
| 282 |
|
If the very last character is a backslash, it is ignored. This gives a |
| 283 |
|
way of passing an empty line as data, since a real empty line termi- |
| 284 |
|
nates the data input. |
| 285 |
|
|
| 286 |
|
If /P was present on the regex, causing the POSIX wrapper API to be |
| 287 |
|
used, only 0 causing REG_NOTBOL and REG_NOTEOL to be passed to |
| 288 |
|
regexec() respectively. |
| 289 |
|
|
| 290 |
|
The use of \x{hh...} to represent UTF-8 characters is not dependent on |
| 291 |
|
the use of the /8 modifier on the pattern. It is recognized always. |
| 292 |
|
There may be any number of hexadecimal digits inside the braces. The |
| 293 |
|
result is from one to six bytes, encoded according to the UTF-8 rules. |
| 294 |
|
|
| 295 |
|
|
| 296 |
|
OUTPUT FROM PCRETEST |
| 297 |
|
|
| 298 |
|
When a match succeeds, pcretest outputs the list of captured substrings |
| 299 |
|
that pcre_exec() returns, starting with number 0 for the string that |
| 300 |
|
matched the whole pattern. Here is an example of an interactive |
| 301 |
|
pcretest run. |
| 302 |
|
|
| 303 |
|
$ pcretest |
| 304 |
|
PCRE version 4.00 08-Jan-2003 |
| 305 |
|
|
| 306 |
|
re> /^abc(\d+)/ |
| 307 |
|
data> abc123 |
| 308 |
|
0: abc123 |
| 309 |
|
1: 123 |
| 310 |
|
data> xyz |
| 311 |
|
No match |
| 312 |
|
|
| 313 |
|
If the strings contain any non-printing characters, they are output as |
| 314 |
|
\0x escapes, or as \x{...} escapes if the /8 modifier was present on |
| 315 |
|
the pattern. If the pattern has the /+ modifier, then the output for |
| 316 |
|
substring 0 is followed by the the rest of the subject string, identi- |
| 317 |
|
fied by "0+" like this: |
| 318 |
|
|
| 319 |
|
re> /cat/+ |
| 320 |
|
data> cataract |
| 321 |
|
0: cat |
| 322 |
|
0+ aract |
| 323 |
|
|
| 324 |
|
If the pattern has the /g or /G modifier, the results of successive |
| 325 |
|
matching attempts are output in sequence, like this: |
| 326 |
|
|
| 327 |
|
re> /\Bi(\w\w)/g |
| 328 |
|
data> Mississippi |
| 329 |
|
0: iss |
| 330 |
|
1: ss |
| 331 |
|
0: iss |
| 332 |
|
1: ss |
| 333 |
|
0: ipp |
| 334 |
|
1: pp |
| 335 |
|
|
| 336 |
|
"No match" is output only if the first match attempt fails. |
| 337 |
|
|
| 338 |
|
If any of the sequences \C, \G, or \L are present in a data line that |
| 339 |
|
is successfully matched, the substrings extracted by the convenience |
| 340 |
|
functions are output with C, G, or L after the string number instead of |
| 341 |
|
a colon. This is in addition to the normal full list. The string length |
| 342 |
|
(that is, the return from the extraction function) is given in paren- |
| 343 |
|
theses after each string for \C and \G. |
| 344 |
|
|
| 345 |
|
Note that while patterns can be continued over several lines (a plain |
| 346 |
|
">" prompt is used for continuations), data lines may not. However new- |
| 347 |
|
lines can be included in data by means of the \n escape. |
| 348 |
|
|
| 349 |
|
|
| 350 |
|
AUTHOR |
| 351 |
|
|
| 352 |
|
Philip Hazel <ph10@cam.ac.uk> |
| 353 |
|
University Computing Service, |
| 354 |
|
Cambridge CB2 3QG, England. |
| 355 |
|
|
| 356 |
|
Last updated: 09 December 2003 |
| 357 |
|
Copyright (c) 1997-2003 University of Cambridge. |
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