713 lines
30 KiB
HTML
713 lines
30 KiB
HTML
<html>
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<head>
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<title>pcretest specification</title>
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</head>
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<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
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<h1>pcretest man page</h1>
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<p>
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Return to the <a href="index.html">PCRE index page</a>.
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</p>
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<p>
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This page is part of the PCRE HTML documentation. It was generated automatically
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from the original man page. If there is any nonsense in it, please consult the
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man page, in case the conversion went wrong.
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<br>
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<ul>
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<li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
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<li><a name="TOC2" href="#SEC2">OPTIONS</a>
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<li><a name="TOC3" href="#SEC3">DESCRIPTION</a>
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<li><a name="TOC4" href="#SEC4">PATTERN MODIFIERS</a>
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<li><a name="TOC5" href="#SEC5">DATA LINES</a>
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<li><a name="TOC6" href="#SEC6">THE ALTERNATIVE MATCHING FUNCTION</a>
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<li><a name="TOC7" href="#SEC7">DEFAULT OUTPUT FROM PCRETEST</a>
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<li><a name="TOC8" href="#SEC8">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a>
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<li><a name="TOC9" href="#SEC9">RESTARTING AFTER A PARTIAL MATCH</a>
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<li><a name="TOC10" href="#SEC10">CALLOUTS</a>
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<li><a name="TOC11" href="#SEC11">NON-PRINTING CHARACTERS</a>
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<li><a name="TOC12" href="#SEC12">SAVING AND RELOADING COMPILED PATTERNS</a>
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<li><a name="TOC13" href="#SEC13">SEE ALSO</a>
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<li><a name="TOC14" href="#SEC14">AUTHOR</a>
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<li><a name="TOC15" href="#SEC15">REVISION</a>
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</ul>
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<br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
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<P>
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<b>pcretest [options] [source] [destination]</b>
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<br>
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<br>
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<b>pcretest</b> 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; for
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details of the regular expressions themselves, see the
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<a href="pcrepattern.html"><b>pcrepattern</b></a>
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documentation. For details of the PCRE library function calls and their
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options, see the
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<a href="pcreapi.html"><b>pcreapi</b></a>
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documentation.
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</P>
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<br><a name="SEC2" href="#TOC1">OPTIONS</a><br>
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<P>
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<b>-b</b>
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Behave as if each regex has the <b>/B</b> (show bytecode) modifier; the internal
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form is output after compilation.
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</P>
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<P>
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<b>-C</b>
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Output the version number of the PCRE library, and all available information
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about the optional features that are included, and then exit.
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</P>
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<P>
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<b>-d</b>
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Behave as if each regex has the <b>/D</b> (debug) modifier; the internal
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form and information about the compiled pattern is output after compilation;
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<b>-d</b> is equivalent to <b>-b -i</b>.
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</P>
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<P>
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<b>-dfa</b>
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Behave as if each data line contains the \D escape sequence; this causes the
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alternative matching function, <b>pcre_dfa_exec()</b>, to be used instead of the
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standard <b>pcre_exec()</b> function (more detail is given below).
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</P>
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<P>
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<b>-help</b>
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Output a brief summary these options and then exit.
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</P>
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<P>
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<b>-i</b>
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Behave as if each regex has the <b>/I</b> modifier; information about the
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compiled pattern is given after compilation.
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</P>
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<P>
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<b>-M</b>
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Behave as if each data line contains the \M escape sequence; this causes
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PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
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calling <b>pcre_exec()</b> repeatedly with different limits.
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</P>
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<P>
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<b>-m</b>
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Output the size of each compiled pattern after it has been compiled. This is
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equivalent to adding <b>/M</b> to each regular expression. For compatibility
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with earlier versions of pcretest, <b>-s</b> is a synonym for <b>-m</b>.
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</P>
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<P>
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<b>-o</b> <i>osize</i>
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Set the number of elements in the output vector that is used when calling
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<b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> to be <i>osize</i>. The default value
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is 45, which is enough for 14 capturing subexpressions for <b>pcre_exec()</b> or
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22 different matches for <b>pcre_dfa_exec()</b>. The vector size can be
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changed for individual matching calls by including \O in the data line (see
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below).
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</P>
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<P>
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<b>-p</b>
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Behave as if each regex has the <b>/P</b> modifier; the POSIX wrapper API is
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used to call PCRE. None of the other options has any effect when <b>-p</b> is
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set.
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</P>
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<P>
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<b>-q</b>
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Do not output the version number of <b>pcretest</b> at the start of execution.
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</P>
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<P>
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<b>-S</b> <i>size</i>
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On Unix-like systems, set the size of the runtime stack to <i>size</i>
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megabytes.
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</P>
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<P>
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<b>-t</b>
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Run each compile, study, and match many times with a timer, and output
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resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with
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<b>-t</b>, because you will then get the size output a zillion times, and the
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timing will be distorted. You can control the number of iterations that are
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used for timing by following <b>-t</b> with a number (as a separate item on the
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command line). For example, "-t 1000" would iterate 1000 times. The default is
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to iterate 500000 times.
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</P>
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<P>
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<b>-tm</b>
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This is like <b>-t</b> except that it times only the matching phase, not the
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compile or study phases.
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</P>
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<br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br>
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<P>
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If <b>pcretest</b> is given two filename arguments, it reads from the first and
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writes to the second. If it is given only one filename argument, it reads from
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that file and writes to stdout. Otherwise, it reads from stdin and writes to
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stdout, and prompts for each line of input, using "re>" to prompt for regular
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expressions, and "data>" to prompt for data lines.
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</P>
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<P>
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When <b>pcretest</b> is built, a configuration option can specify that it should
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be linked with the <b>libreadline</b> library. When this is done, if the input
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is from a terminal, it is read using the <b>readline()</b> function. This
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provides line-editing and history facilities. The output from the <b>-help</b>
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option states whether or not <b>readline()</b> will be used.
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</P>
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<P>
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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.
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</P>
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<P>
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Each data line is matched separately and independently. If you want to do
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multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
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etc., depending on the newline setting) in a single line of input to encode the
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newline sequences. There is no limit on the length of data lines; the input
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buffer is automatically extended if it is too small.
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</P>
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<P>
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An empty line signals the end of the data lines, at which point a new regular
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expression is read. The regular expressions are given enclosed in any
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non-alphanumeric delimiters other than backslash, for example:
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<pre>
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/(a|bc)x+yz/
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</pre>
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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. It is possible to include the delimiter within the pattern
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by escaping it, for example
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<pre>
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/abc\/def/
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</pre>
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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-alphanumeric, 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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<pre>
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/abc/\
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</pre>
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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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<pre>
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/abc\/
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</pre>
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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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</P>
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<br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
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<P>
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A pattern may be followed by any number of modifiers, which are mostly single
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characters. Following Perl usage, these are referred to below as, for example,
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"the <b>/i</b> modifier", even though the delimiter of the pattern need not
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always be a slash, and no slash is used when writing modifiers. Whitespace may
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appear between the final pattern delimiter and the first modifier, and between
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the modifiers themselves.
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</P>
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<P>
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The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
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PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
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<b>pcre_compile()</b> is called. These four modifier letters have the same
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effect as they do in Perl. For example:
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<pre>
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/caseless/i
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</pre>
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The following table shows additional modifiers for setting PCRE options that do
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not correspond to anything in Perl:
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<pre>
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<b>/A</b> PCRE_ANCHORED
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<b>/C</b> PCRE_AUTO_CALLOUT
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<b>/E</b> PCRE_DOLLAR_ENDONLY
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<b>/f</b> PCRE_FIRSTLINE
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<b>/J</b> PCRE_DUPNAMES
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<b>/N</b> PCRE_NO_AUTO_CAPTURE
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<b>/U</b> PCRE_UNGREEDY
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<b>/X</b> PCRE_EXTRA
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<b>/<JS></b> PCRE_JAVASCRIPT_COMPAT
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<b>/<cr></b> PCRE_NEWLINE_CR
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<b>/<lf></b> PCRE_NEWLINE_LF
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<b>/<crlf></b> PCRE_NEWLINE_CRLF
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<b>/<anycrlf></b> PCRE_NEWLINE_ANYCRLF
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<b>/<any></b> PCRE_NEWLINE_ANY
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<b>/<bsr_anycrlf></b> PCRE_BSR_ANYCRLF
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<b>/<bsr_unicode></b> PCRE_BSR_UNICODE
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</pre>
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Those specifying line ending sequences are literal strings as shown, but the
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letters can be in either case. This example sets multiline matching with CRLF
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as the line ending sequence:
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<pre>
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/^abc/m<crlf>
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</pre>
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Details of the meanings of these PCRE options are given in the
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<a href="pcreapi.html"><b>pcreapi</b></a>
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documentation.
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</P>
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<br><b>
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Finding all matches in a string
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</b><br>
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<P>
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Searching for all possible matches within each subject string can be requested
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by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
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again to search the remainder of the subject string. The difference between
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<b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
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<b>pcre_exec()</b> to start searching at a new point within the entire string
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(which is in effect what Perl does), whereas the latter passes over a shortened
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substring. This makes a difference to the matching process if the pattern
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begins with a lookbehind assertion (including \b or \B).
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</P>
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<P>
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If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
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empty 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 point.
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If this second match fails, the start offset is advanced by one, and the normal
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match is retried. This imitates the way Perl handles such cases when using the
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<b>/g</b> modifier or the <b>split()</b> function.
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</P>
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<br><b>
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Other modifiers
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</b><br>
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<P>
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There are yet more modifiers for controlling the way <b>pcretest</b>
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operates.
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</P>
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<P>
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The <b>/+</b> modifier requests that as well as outputting the substring that
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matched the entire pattern, pcretest should in addition output the remainder of
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the subject string. This is useful for tests where the subject contains
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multiple copies of the same substring.
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</P>
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<P>
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The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
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output a representation of the compiled byte code after compilation. Normally
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this information contains length and offset values; however, if <b>/Z</b> is
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also present, this data is replaced by spaces. This is a special feature for
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use in the automatic test scripts; it ensures that the same output is generated
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for different internal link sizes.
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</P>
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<P>
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The <b>/L</b> modifier must be followed directly by the name of a locale, for
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example,
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<pre>
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/pattern/Lfr_FR
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</pre>
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For this reason, it must be the last modifier. The given locale is set,
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<b>pcre_maketables()</b> is called to build a set of character tables for the
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locale, and this is then passed to <b>pcre_compile()</b> when compiling the
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regular expression. Without an <b>/L</b> modifier, NULL is passed as the tables
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pointer; that is, <b>/L</b> applies only to the expression on which it appears.
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</P>
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<P>
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The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
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compiled pattern (whether it is anchored, has a fixed first character, and
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so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
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pattern. If the pattern is studied, the results of that are also output.
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</P>
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<P>
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The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
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<b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers.
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</P>
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<P>
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The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
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fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
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facility is for testing the feature in PCRE that allows it to execute patterns
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that were compiled on a host with a different endianness. This feature is not
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available when the POSIX interface to PCRE is being used, that is, when the
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<b>/P</b> pattern modifier is specified. See also the section about saving and
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reloading compiled patterns below.
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</P>
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<P>
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The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
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expression has been compiled, and the results used when the expression is
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matched.
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</P>
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<P>
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The <b>/M</b> modifier causes the size of memory block used to hold the compiled
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pattern to be output.
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</P>
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<P>
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The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
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API rather than its native API. When this is done, all other modifiers except
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<b>/i</b>, <b>/m</b>, and <b>/+</b> are ignored. REG_ICASE is set if <b>/i</b> is
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present, and REG_NEWLINE is set if <b>/m</b> is present. The wrapper functions
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force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
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</P>
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<P>
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The <b>/8</b> modifier causes <b>pcretest</b> to call PCRE with the PCRE_UTF8
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option set. This turns on support for UTF-8 character handling in PCRE,
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provided that it was compiled with this support enabled. This modifier also
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causes any non-printing characters in output strings to be printed using the
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\x{hh...} notation if they are valid UTF-8 sequences.
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</P>
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<P>
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If the <b>/?</b> modifier is used with <b>/8</b>, it causes <b>pcretest</b> to
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call <b>pcre_compile()</b> 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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</P>
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<br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
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<P>
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Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
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whitespace is removed, and it is then scanned for \ escapes. Some of these are
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pretty esoteric features, intended for checking out some of the more
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complicated features of PCRE. If you are just testing "ordinary" regular
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expressions, you probably don't need any of these. The following escapes are
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recognized:
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<pre>
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\a alarm (BEL, \x07)
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\b backspace (\x08)
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\e escape (\x27)
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\f formfeed (\x0c)
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\n newline (\x0a)
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\qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
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\r carriage return (\x0d)
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\t tab (\x09)
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\v vertical tab (\x0b)
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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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\x{hh...} hexadecimal character, any number of digits in UTF-8 mode
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\A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
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\B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
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\Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
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\Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
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ated by next non alphanumeric character)
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\C+ show the current captured substrings at callout time
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\C- do not supply a callout function
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\C!n return 1 instead of 0 when callout number n is reached
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\C!n!m return 1 instead of 0 when callout number n is reached for the nth time
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\C*n pass the number n (may be negative) as callout data; this is used as the callout return value
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\D use the <b>pcre_dfa_exec()</b> match function
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\F only shortest match for <b>pcre_dfa_exec()</b>
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\Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
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\Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
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ated by next non-alphanumeric character)
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\L call pcre_get_substringlist() after a successful match
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\M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
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\N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
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\Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
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\P pass the PCRE_PARTIAL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
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\Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
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\R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
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\S output details of memory get/free calls during matching
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\Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
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\? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
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\>dd start the match at offset dd (any number of digits);
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this sets the <i>startoffset</i> argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
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\<cr> pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
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\<lf> pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
\<crlf> pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
\<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
\<any> pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
</pre>
|
|
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.
|
|
</P>
|
|
<P>
|
|
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 terminates the data
|
|
input.
|
|
</P>
|
|
<P>
|
|
If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
|
|
different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
|
|
fields of the <b>pcre_extra</b> data structure, until it finds the minimum
|
|
numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
|
|
<i>match_limit</i> 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 <i>match_limit_recursion</i> 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.
|
|
</P>
|
|
<P>
|
|
When \O is used, the value specified may be higher or lower than the size set
|
|
by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
|
|
the call of <b>pcre_exec()</b> for the line in which it appears.
|
|
</P>
|
|
<P>
|
|
If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
|
|
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
|
|
<b>regexec()</b>.
|
|
</P>
|
|
<P>
|
|
The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
|
|
of the <b>/8</b> 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.
|
|
</P>
|
|
<br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
|
|
<P>
|
|
By default, <b>pcretest</b> uses the standard PCRE matching function,
|
|
<b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
|
|
alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
|
|
different way, and has some restrictions. The differences between the two
|
|
functions are described in the
|
|
<a href="pcrematching.html"><b>pcrematching</b></a>
|
|
documentation.
|
|
</P>
|
|
<P>
|
|
If a data line contains the \D escape sequence, or if the command line
|
|
contains the <b>-dfa</b> 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.
|
|
</P>
|
|
<br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
|
|
<P>
|
|
This section describes the output when the normal matching function,
|
|
<b>pcre_exec()</b>, is being used.
|
|
</P>
|
|
<P>
|
|
When a match succeeds, pcretest outputs the list of captured substrings that
|
|
<b>pcre_exec()</b> returns, starting with number 0 for the string that matched
|
|
the whole pattern. Otherwise, it outputs "No match" or "Partial match"
|
|
when <b>pcre_exec()</b> returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
|
|
respectively, and otherwise the PCRE negative error number. Here is an example
|
|
of an interactive <b>pcretest</b> run.
|
|
<pre>
|
|
$ pcretest
|
|
PCRE version 7.0 30-Nov-2006
|
|
|
|
re> /^abc(\d+)/
|
|
data> abc123
|
|
0: abc123
|
|
1: 123
|
|
data> xyz
|
|
No match
|
|
</pre>
|
|
Note that unset capturing substrings that are not followed by one that is set
|
|
are not returned by <b>pcre_exec()</b>, and are not shown by <b>pcretest</b>. 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.
|
|
<pre>
|
|
re> /(a)|(b)/
|
|
data> a
|
|
0: a
|
|
1: a
|
|
data> b
|
|
0: b
|
|
1: <unset>
|
|
2: b
|
|
</pre>
|
|
If the strings contain any non-printing characters, they are output as \0x
|
|
escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
|
|
pattern. See below for the definition of non-printing characters. If the
|
|
pattern has the <b>/+</b> modifier, the output for substring 0 is followed by
|
|
the the rest of the subject string, identified by "0+" like this:
|
|
<pre>
|
|
re> /cat/+
|
|
data> cataract
|
|
0: cat
|
|
0+ aract
|
|
</pre>
|
|
If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
|
|
matching attempts are output in sequence, like this:
|
|
<pre>
|
|
re> /\Bi(\w\w)/g
|
|
data> Mississippi
|
|
0: iss
|
|
1: ss
|
|
0: iss
|
|
1: ss
|
|
0: ipp
|
|
1: pp
|
|
</pre>
|
|
"No match" is output only if the first match attempt fails.
|
|
</P>
|
|
<P>
|
|
If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> 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
|
|
parentheses after each string for <b>\C</b> and <b>\G</b>.
|
|
</P>
|
|
<P>
|
|
Note that whereas patterns can be continued over several lines (a plain ">"
|
|
prompt is used for continuations), data lines may not. However newlines can be
|
|
included in data by means of the \n escape (or \r, \r\n, etc., depending on
|
|
the newline sequence setting).
|
|
</P>
|
|
<br><a name="SEC8" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
|
|
<P>
|
|
When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
|
|
means of the \D escape sequence or the <b>-dfa</b> 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:
|
|
<pre>
|
|
re> /(tang|tangerine|tan)/
|
|
data> yellow tangerine\D
|
|
0: tangerine
|
|
1: tang
|
|
2: tan
|
|
</pre>
|
|
(Using the normal matching function on this data finds only "tang".) The
|
|
longest matching string is always given first (and numbered zero).
|
|
</P>
|
|
<P>
|
|
If <b>/g</b> is present on the pattern, the search for further matches resumes
|
|
at the end of the longest match. For example:
|
|
<pre>
|
|
re> /(tang|tangerine|tan)/g
|
|
data> yellow tangerine and tangy sultana\D
|
|
0: tangerine
|
|
1: tang
|
|
2: tan
|
|
0: tang
|
|
1: tan
|
|
0: tan
|
|
</pre>
|
|
Since the matching function does not support substring capture, the escape
|
|
sequences that are concerned with captured substrings are not relevant.
|
|
</P>
|
|
<br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
|
|
<P>
|
|
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:
|
|
<pre>
|
|
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
|
|
</pre>
|
|
For further information about partial matching, see the
|
|
<a href="pcrepartial.html"><b>pcrepartial</b></a>
|
|
documentation.
|
|
</P>
|
|
<br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
|
|
<P>
|
|
If the pattern contains any callout requests, <b>pcretest</b>'s callout function
|
|
is called during matching. This works with both matching functions. 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
|
|
<pre>
|
|
--->pqrabcdef
|
|
0 ^ ^ \d
|
|
</pre>
|
|
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.
|
|
</P>
|
|
<P>
|
|
Callouts numbered 255 are assumed to be automatic callouts, inserted as a
|
|
result of the <b>/C</b> pattern modifier. In this case, instead of showing the
|
|
callout number, the offset in the pattern, preceded by a plus, is output. For
|
|
example:
|
|
<pre>
|
|
re> /\d?[A-E]\*/C
|
|
data> E*
|
|
--->E*
|
|
+0 ^ \d?
|
|
+3 ^ [A-E]
|
|
+8 ^^ \*
|
|
+10 ^ ^
|
|
0: E*
|
|
</pre>
|
|
The callout function in <b>pcretest</b> returns zero (carry on matching) by
|
|
default, but you can use a \C item in a data line (as described above) to
|
|
change this.
|
|
</P>
|
|
<P>
|
|
Inserting callouts can be helpful when using <b>pcretest</b> to check
|
|
complicated regular expressions. For further information about callouts, see
|
|
the
|
|
<a href="pcrecallout.html"><b>pcrecallout</b></a>
|
|
documentation.
|
|
</P>
|
|
<br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
|
|
<P>
|
|
When <b>pcretest</b> 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.
|
|
</P>
|
|
<P>
|
|
When <b>pcretest</b> 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 <b>/L</b> modifier). In this case, the <b>isprint()</b>
|
|
function to distinguish printing and non-printing characters.
|
|
</P>
|
|
<br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
|
|
<P>
|
|
The facilities described in this section are not available when the POSIX
|
|
inteface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
|
|
specified.
|
|
</P>
|
|
<P>
|
|
When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
|
|
compiled pattern to a file, by following the modifiers with > and a file name.
|
|
For example:
|
|
<pre>
|
|
/pattern/im >/some/file
|
|
</pre>
|
|
See the
|
|
<a href="pcreprecompile.html"><b>pcreprecompile</b></a>
|
|
documentation for a discussion about saving and re-using compiled patterns.
|
|
</P>
|
|
<P>
|
|
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 second length is zero. The lengths are followed by an
|
|
exact copy of the compiled pattern. If there is additional study data, this
|
|
follows immediately after the compiled pattern. After writing the file,
|
|
<b>pcretest</b> expects to read a new pattern.
|
|
</P>
|
|
<P>
|
|
A saved pattern can be reloaded into <b>pcretest</b> by specifing < and a file
|
|
name instead of a pattern. The name of the file must not contain a < character,
|
|
as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by <
|
|
characters.
|
|
For example:
|
|
<pre>
|
|
re> </some/file
|
|
Compiled regex loaded from /some/file
|
|
No study data
|
|
</pre>
|
|
When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
|
|
the usual way.
|
|
</P>
|
|
<P>
|
|
You can copy a file written by <b>pcretest</b> 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.
|
|
</P>
|
|
<P>
|
|
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.
|
|
</P>
|
|
<P>
|
|
The ability to save and reload files in <b>pcretest</b> is intended for testing
|
|
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 <b>pcretest</b> to crash.
|
|
Finally, if you attempt to load a file that is not in the correct format, the
|
|
result is undefined.
|
|
</P>
|
|
<br><a name="SEC13" href="#TOC1">SEE ALSO</a><br>
|
|
<P>
|
|
<b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
|
|
<b>pcrepartial</b>(d), <b>pcrepattern</b>(3), <b>pcreprecompile</b>(3).
|
|
</P>
|
|
<br><a name="SEC14" href="#TOC1">AUTHOR</a><br>
|
|
<P>
|
|
Philip Hazel
|
|
<br>
|
|
University Computing Service
|
|
<br>
|
|
Cambridge CB2 3QH, England.
|
|
<br>
|
|
</P>
|
|
<br><a name="SEC15" href="#TOC1">REVISION</a><br>
|
|
<P>
|
|
Last updated: 10 March 2009
|
|
<br>
|
|
Copyright © 1997-2009 University of Cambridge.
|
|
<br>
|
|
<p>
|
|
Return to the <a href="index.html">PCRE index page</a>.
|
|
</p>
|