617 lines
26 KiB
HTML
617 lines
26 KiB
HTML
<html>
|
|
<head>
|
|
<title>pcretest specification</title>
|
|
</head>
|
|
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
|
<h1>pcretest man page</h1>
|
|
<p>
|
|
Return to the <a href="index.html">PCRE index page</a>.
|
|
</p>
|
|
<p>
|
|
This page is part of the PCRE HTML documentation. It was generated automatically
|
|
from the original man page. If there is any nonsense in it, please consult the
|
|
man page, in case the conversion went wrong.
|
|
<br>
|
|
<ul>
|
|
<li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
|
|
<li><a name="TOC2" href="#SEC2">OPTIONS</a>
|
|
<li><a name="TOC3" href="#SEC3">DESCRIPTION</a>
|
|
<li><a name="TOC4" href="#SEC4">PATTERN MODIFIERS</a>
|
|
<li><a name="TOC5" href="#SEC5">DATA LINES</a>
|
|
<li><a name="TOC6" href="#SEC6">THE ALTERNATIVE MATCHING FUNCTION</a>
|
|
<li><a name="TOC7" href="#SEC7">DEFAULT OUTPUT FROM PCRETEST</a>
|
|
<li><a name="TOC8" href="#SEC8">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a>
|
|
<li><a name="TOC9" href="#SEC9">RESTARTING AFTER A PARTIAL MATCH</a>
|
|
<li><a name="TOC10" href="#SEC10">CALLOUTS</a>
|
|
<li><a name="TOC11" href="#SEC11">SAVING AND RELOADING COMPILED PATTERNS</a>
|
|
<li><a name="TOC12" href="#SEC12">AUTHOR</a>
|
|
</ul>
|
|
<br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
|
|
<P>
|
|
<b>pcretest [options] [source] [destination]</b>
|
|
<br>
|
|
<br>
|
|
<b>pcretest</b> was written as a test program for the PCRE regular expression
|
|
library itself, but it can also be used for experimenting with regular
|
|
expressions. This document describes the features of the test program; for
|
|
details of the regular expressions themselves, see the
|
|
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
|
documentation. For details of the PCRE library function calls and their
|
|
options, see the
|
|
<a href="pcreapi.html"><b>pcreapi</b></a>
|
|
documentation.
|
|
</P>
|
|
<br><a name="SEC2" href="#TOC1">OPTIONS</a><br>
|
|
<P>
|
|
<b>-C</b>
|
|
Output the version number of the PCRE library, and all available information
|
|
about the optional features that are included, and then exit.
|
|
</P>
|
|
<P>
|
|
<b>-d</b>
|
|
Behave as if each regex has the <b>/D</b> (debug) modifier; the internal
|
|
form is output after compilation.
|
|
</P>
|
|
<P>
|
|
<b>-dfa</b>
|
|
Behave as if each data line contains the \D escape sequence; this causes the
|
|
alternative matching function, <b>pcre_dfa_exec()</b>, to be used instead of the
|
|
standard <b>pcre_exec()</b> function (more detail is given below).
|
|
</P>
|
|
<P>
|
|
<b>-i</b>
|
|
Behave as if each regex has the <b>/I</b> modifier; information about the
|
|
compiled pattern is given after compilation.
|
|
</P>
|
|
<P>
|
|
<b>-m</b>
|
|
Output the size of each compiled pattern after it has been compiled. This is
|
|
equivalent to adding <b>/M</b> to each regular expression. For compatibility
|
|
with earlier versions of pcretest, <b>-s</b> is a synonym for <b>-m</b>.
|
|
</P>
|
|
<P>
|
|
<b>-o</b> <i>osize</i>
|
|
Set the number of elements in the output vector that is used when calling
|
|
<b>pcre_exec()</b> to be <i>osize</i>. The default value is 45, which is enough
|
|
for 14 capturing subexpressions. The vector size can be changed for individual
|
|
matching calls by including \O in the data line (see below).
|
|
</P>
|
|
<P>
|
|
<b>-p</b>
|
|
Behave as if each regex has the <b>/P</b> modifier; the POSIX wrapper API is
|
|
used to call PCRE. None of the other options has any effect when <b>-p</b> is
|
|
set.
|
|
</P>
|
|
<P>
|
|
<b>-q</b>
|
|
Do not output the version number of <b>pcretest</b> at the start of execution.
|
|
</P>
|
|
<P>
|
|
<b>-S</b> <i>size</i>
|
|
On Unix-like systems, set the size of the runtime stack to <i>size</i>
|
|
megabytes.
|
|
</P>
|
|
<P>
|
|
<b>-t</b>
|
|
Run each compile, study, and match many times with a timer, and output
|
|
resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with
|
|
<b>-t</b>, because you will then get the size output a zillion times, and the
|
|
timing will be distorted.
|
|
</P>
|
|
<br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br>
|
|
<P>
|
|
If <b>pcretest</b> is given two filename arguments, it reads from the first and
|
|
writes to the second. If it is given only one filename argument, it reads from
|
|
that file and writes to stdout. Otherwise, it reads from stdin and writes to
|
|
stdout, and prompts for each line of input, using "re>" to prompt for regular
|
|
expressions, and "data>" to prompt for data lines.
|
|
</P>
|
|
<P>
|
|
The program handles any number of sets of input on a single input file. Each
|
|
set starts with a regular expression, and continues with any number of data
|
|
lines to be matched against the pattern.
|
|
</P>
|
|
<P>
|
|
Each data line is matched separately and independently. If you want to do
|
|
multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
|
|
depending on the newline setting) in a single line of input to encode the
|
|
newline characters. There is no limit on the length of data lines; the input
|
|
buffer is automatically extended if it is too small.
|
|
</P>
|
|
<P>
|
|
An empty line signals the end of the data lines, at which point a new regular
|
|
expression is read. The regular expressions are given enclosed in any
|
|
non-alphanumeric delimiters other than backslash, for example:
|
|
<pre>
|
|
/(a|bc)x+yz/
|
|
</pre>
|
|
White space before the initial delimiter is ignored. A regular expression may
|
|
be continued over several input lines, in which case the newline characters are
|
|
included within it. It is possible to include the delimiter within the pattern
|
|
by escaping it, for example
|
|
<pre>
|
|
/abc\/def/
|
|
</pre>
|
|
If you do so, the escape and the delimiter form part of the pattern, but since
|
|
delimiters are always non-alphanumeric, this does not affect its interpretation.
|
|
If the terminating delimiter is immediately followed by a backslash, for
|
|
example,
|
|
<pre>
|
|
/abc/\
|
|
</pre>
|
|
then a backslash is added to the end of the pattern. This is done to provide a
|
|
way of testing the error condition that arises if a pattern finishes with a
|
|
backslash, because
|
|
<pre>
|
|
/abc\/
|
|
</pre>
|
|
is interpreted as the first line of a pattern that starts with "abc/", causing
|
|
pcretest to read the next line as a continuation of the regular expression.
|
|
</P>
|
|
<br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
|
|
<P>
|
|
A pattern may be followed by any number of modifiers, which are mostly single
|
|
characters. Following Perl usage, these are referred to below as, for example,
|
|
"the <b>/i</b> modifier", even though the delimiter of the pattern need not
|
|
always be a slash, and no slash is used when writing modifiers. Whitespace may
|
|
appear between the final pattern delimiter and the first modifier, and between
|
|
the modifiers themselves.
|
|
</P>
|
|
<P>
|
|
The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
|
|
PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
|
|
<b>pcre_compile()</b> is called. These four modifier letters have the same
|
|
effect as they do in Perl. For example:
|
|
<pre>
|
|
/caseless/i
|
|
</pre>
|
|
The following table shows additional modifiers for setting PCRE options that do
|
|
not correspond to anything in Perl:
|
|
<pre>
|
|
<b>/A</b> PCRE_ANCHORED
|
|
<b>/C</b> PCRE_AUTO_CALLOUT
|
|
<b>/E</b> PCRE_DOLLAR_ENDONLY
|
|
<b>/f</b> PCRE_FIRSTLINE
|
|
<b>/J</b> PCRE_DUPNAMES
|
|
<b>/N</b> PCRE_NO_AUTO_CAPTURE
|
|
<b>/U</b> PCRE_UNGREEDY
|
|
<b>/X</b> PCRE_EXTRA
|
|
<b>/<cr></b> PCRE_NEWLINE_CR
|
|
<b>/<lf></b> PCRE_NEWLINE_LF
|
|
<b>/<crlf></b> PCRE_NEWLINE_CRLF
|
|
</pre>
|
|
Those specifying line endings are literal strings as shown. Details of the
|
|
meanings of these PCRE options are given in the
|
|
<a href="pcreapi.html"><b>pcreapi</b></a>
|
|
documentation.
|
|
</P>
|
|
<br><b>
|
|
Finding all matches in a string
|
|
</b><br>
|
|
<P>
|
|
Searching for all possible matches within each subject string can be requested
|
|
by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
|
|
again to search the remainder of the subject string. The difference between
|
|
<b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
|
|
<b>pcre_exec()</b> to start searching at a new point within the entire string
|
|
(which is in effect what Perl does), whereas the latter passes over a shortened
|
|
substring. This makes a difference to the matching process if the pattern
|
|
begins with a lookbehind assertion (including \b or \B).
|
|
</P>
|
|
<P>
|
|
If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
|
|
empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
|
|
flags set in order to search for another, non-empty, match at the same point.
|
|
If this second match fails, the start offset is advanced by one, and the normal
|
|
match is retried. This imitates the way Perl handles such cases when using the
|
|
<b>/g</b> modifier or the <b>split()</b> function.
|
|
</P>
|
|
<br><b>
|
|
Other modifiers
|
|
</b><br>
|
|
<P>
|
|
There are yet more modifiers for controlling the way <b>pcretest</b>
|
|
operates.
|
|
</P>
|
|
<P>
|
|
The <b>/+</b> modifier requests that as well as outputting the substring that
|
|
matched the entire pattern, pcretest should in addition output the remainder of
|
|
the subject string. This is useful for tests where the subject contains
|
|
multiple copies of the same substring.
|
|
</P>
|
|
<P>
|
|
The <b>/L</b> modifier must be followed directly by the name of a locale, for
|
|
example,
|
|
<pre>
|
|
/pattern/Lfr_FR
|
|
</pre>
|
|
For this reason, it must be the last modifier. The given locale is set,
|
|
<b>pcre_maketables()</b> is called to build a set of character tables for the
|
|
locale, and this is then passed to <b>pcre_compile()</b> when compiling the
|
|
regular expression. Without an <b>/L</b> modifier, NULL is passed as the tables
|
|
pointer; that is, <b>/L</b> applies only to the expression on which it appears.
|
|
</P>
|
|
<P>
|
|
The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
|
|
compiled pattern (whether it is anchored, has a fixed first character, and
|
|
so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
|
|
pattern. If the pattern is studied, the results of that are also output.
|
|
</P>
|
|
<P>
|
|
The <b>/D</b> modifier is a PCRE debugging feature, which also assumes <b>/I</b>.
|
|
It causes the internal form of compiled regular expressions to be output after
|
|
compilation. If the pattern was studied, the information returned is also
|
|
output.
|
|
</P>
|
|
<P>
|
|
The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
|
|
fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
|
|
facility is for testing the feature in PCRE that allows it to execute patterns
|
|
that were compiled on a host with a different endianness. This feature is not
|
|
available when the POSIX interface to PCRE is being used, that is, when the
|
|
<b>/P</b> pattern modifier is specified. See also the section about saving and
|
|
reloading compiled patterns below.
|
|
</P>
|
|
<P>
|
|
The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
|
|
expression has been compiled, and the results used when the expression is
|
|
matched.
|
|
</P>
|
|
<P>
|
|
The <b>/M</b> modifier causes the size of memory block used to hold the compiled
|
|
pattern to be output.
|
|
</P>
|
|
<P>
|
|
The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
|
|
API rather than its native API. When this is done, all other modifiers except
|
|
<b>/i</b>, <b>/m</b>, and <b>/+</b> are ignored. REG_ICASE is set if <b>/i</b> is
|
|
present, and REG_NEWLINE is set if <b>/m</b> is present. The wrapper functions
|
|
force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
|
|
</P>
|
|
<P>
|
|
The <b>/8</b> modifier causes <b>pcretest</b> to call PCRE with the PCRE_UTF8
|
|
option set. This turns on support for UTF-8 character handling in PCRE,
|
|
provided that it was compiled with this support enabled. This modifier also
|
|
causes any non-printing characters in output strings to be printed using the
|
|
\x{hh...} notation if they are valid UTF-8 sequences.
|
|
</P>
|
|
<P>
|
|
If the <b>/?</b> modifier is used with <b>/8</b>, it causes <b>pcretest</b> to
|
|
call <b>pcre_compile()</b> with the PCRE_NO_UTF8_CHECK option, to suppress the
|
|
checking of the string for UTF-8 validity.
|
|
</P>
|
|
<br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
|
|
<P>
|
|
Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
|
|
whitespace is removed, and it is then scanned for \ escapes. Some of these are
|
|
pretty esoteric features, intended for checking out some of the more
|
|
complicated features of PCRE. If you are just testing "ordinary" regular
|
|
expressions, you probably don't need any of these. The following escapes are
|
|
recognized:
|
|
<pre>
|
|
\a alarm (= BEL)
|
|
\b backspace
|
|
\e escape
|
|
\f formfeed
|
|
\n newline
|
|
\qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
|
|
\r carriage return
|
|
\t tab
|
|
\v vertical tab
|
|
\nnn octal character (up to 3 octal digits)
|
|
\xhh hexadecimal character (up to 2 hex digits)
|
|
\x{hh...} hexadecimal character, any number of digits in UTF-8 mode
|
|
\A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
\B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
\Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
|
|
\Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
|
|
ated by next non alphanumeric character)
|
|
\C+ show the current captured substrings at callout time
|
|
\C- do not supply a callout function
|
|
\C!n return 1 instead of 0 when callout number n is reached
|
|
\C!n!m return 1 instead of 0 when callout number n is reached for the nth time
|
|
\C*n pass the number n (may be negative) as callout data; this is used as the callout return value
|
|
\D use the <b>pcre_dfa_exec()</b> match function
|
|
\F only shortest match for <b>pcre_dfa_exec()</b>
|
|
\Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
|
|
\Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
|
|
ated by next non-alphanumeric character)
|
|
\L call pcre_get_substringlist() after a successful match
|
|
\M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
|
|
\N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
\Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
|
|
\P pass the PCRE_PARTIAL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
\Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
|
|
\R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
|
|
\S output details of memory get/free calls during matching
|
|
\Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
\? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
\>dd start the match at offset dd (any number of digits);
|
|
this sets the <i>startoffset</i> argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
\<cr> pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
|
|
\<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>
|
|
</pre>
|
|
The escapes that specify line endings are literal strings, exactly as shown.
|
|
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 UTF-8 rules.
|
|
</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 5.00 07-Sep-2004
|
|
|
|
re> /^abc(\d+)/
|
|
data> abc123
|
|
0: abc123
|
|
1: 123
|
|
data> xyz
|
|
No match
|
|
</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. 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 while 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 or \r\n for those newline
|
|
settings).
|
|
</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 \fB/g\P 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">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="SEC12" href="#TOC1">AUTHOR</a><br>
|
|
<P>
|
|
Philip Hazel
|
|
<br>
|
|
University Computing Service,
|
|
<br>
|
|
Cambridge CB2 3QG, England.
|
|
</P>
|
|
<P>
|
|
Last updated: 29 June 2006
|
|
<br>
|
|
Copyright © 1997-2006 University of Cambridge.
|
|
<p>
|
|
Return to the <a href="index.html">PCRE index page</a>.
|
|
</p>
|