Regex: Add PCRE 8.32 in tools directory.
This commit is contained in:
Arkshine
292
tools/pcre/doc/html/pcreposix.html
Normal file
292
tools/pcre/doc/html/pcreposix.html
Normal file
@ -0,0 +1,292 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcreposix specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcreposix 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 OF POSIX API</a>
|
||||
<li><a name="TOC2" href="#SEC2">DESCRIPTION</a>
|
||||
<li><a name="TOC3" href="#SEC3">COMPILING A PATTERN</a>
|
||||
<li><a name="TOC4" href="#SEC4">MATCHING NEWLINE CHARACTERS</a>
|
||||
<li><a name="TOC5" href="#SEC5">MATCHING A PATTERN</a>
|
||||
<li><a name="TOC6" href="#SEC6">ERROR MESSAGES</a>
|
||||
<li><a name="TOC7" href="#SEC7">MEMORY USAGE</a>
|
||||
<li><a name="TOC8" href="#SEC8">AUTHOR</a>
|
||||
<li><a name="TOC9" href="#SEC9">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">SYNOPSIS OF POSIX API</a><br>
|
||||
<P>
|
||||
<b>#include <pcreposix.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int regcomp(regex_t *<i>preg</i>, const char *<i>pattern</i>,</b>
|
||||
<b>int <i>cflags</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int regexec(regex_t *<i>preg</i>, const char *<i>string</i>,</b>
|
||||
<b>size_t <i>nmatch</i>, regmatch_t <i>pmatch</i>[], int <i>eflags</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>size_t regerror(int <i>errcode</i>, const regex_t *<i>preg</i>,</b>
|
||||
<b>char *<i>errbuf</i>, size_t <i>errbuf_size</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void regfree(regex_t *<i>preg</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
|
||||
<P>
|
||||
This set of functions provides a POSIX-style API for the PCRE regular
|
||||
expression 8-bit library. See the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation for a description of PCRE's native API, which contains much
|
||||
additional functionality. There is no POSIX-style wrapper for PCRE's 16-bit
|
||||
and 32-bit library.
|
||||
</P>
|
||||
<P>
|
||||
The functions described here are just wrapper functions that ultimately call
|
||||
the PCRE native API. Their prototypes are defined in the <b>pcreposix.h</b>
|
||||
header file, and on Unix systems the library itself is called
|
||||
<b>pcreposix.a</b>, so can be accessed by adding <b>-lpcreposix</b> to the
|
||||
command for linking an application that uses them. Because the POSIX functions
|
||||
call the native ones, it is also necessary to add <b>-lpcre</b>.
|
||||
</P>
|
||||
<P>
|
||||
I have implemented only those POSIX option bits that can be reasonably mapped
|
||||
to PCRE native options. In addition, the option REG_EXTENDED is defined with
|
||||
the value zero. This has no effect, but since programs that are written to the
|
||||
POSIX interface often use it, this makes it easier to slot in PCRE as a
|
||||
replacement library. Other POSIX options are not even defined.
|
||||
</P>
|
||||
<P>
|
||||
There are also some other options that are not defined by POSIX. These have
|
||||
been added at the request of users who want to make use of certain
|
||||
PCRE-specific features via the POSIX calling interface.
|
||||
</P>
|
||||
<P>
|
||||
When PCRE is called via these functions, it is only the API that is POSIX-like
|
||||
in style. The syntax and semantics of the regular expressions themselves are
|
||||
still those of Perl, subject to the setting of various PCRE options, as
|
||||
described below. "POSIX-like in style" means that the API approximates to the
|
||||
POSIX definition; it is not fully POSIX-compatible, and in multi-byte encoding
|
||||
domains it is probably even less compatible.
|
||||
</P>
|
||||
<P>
|
||||
The header for these functions is supplied as <b>pcreposix.h</b> to avoid any
|
||||
potential clash with other POSIX libraries. It can, of course, be renamed or
|
||||
aliased as <b>regex.h</b>, which is the "correct" name. It provides two
|
||||
structure types, <i>regex_t</i> for compiled internal forms, and
|
||||
<i>regmatch_t</i> for returning captured substrings. It also defines some
|
||||
constants whose names start with "REG_"; these are used for setting options and
|
||||
identifying error codes.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">COMPILING A PATTERN</a><br>
|
||||
<P>
|
||||
The function <b>regcomp()</b> is called to compile a pattern into an
|
||||
internal form. The pattern is a C string terminated by a binary zero, and
|
||||
is passed in the argument <i>pattern</i>. The <i>preg</i> argument is a pointer
|
||||
to a <b>regex_t</b> structure that is used as a base for storing information
|
||||
about the compiled regular expression.
|
||||
</P>
|
||||
<P>
|
||||
The argument <i>cflags</i> is either zero, or contains one or more of the bits
|
||||
defined by the following macros:
|
||||
<pre>
|
||||
REG_DOTALL
|
||||
</pre>
|
||||
The PCRE_DOTALL option is set when the regular expression is passed for
|
||||
compilation to the native function. Note that REG_DOTALL is not part of the
|
||||
POSIX standard.
|
||||
<pre>
|
||||
REG_ICASE
|
||||
</pre>
|
||||
The PCRE_CASELESS option is set when the regular expression is passed for
|
||||
compilation to the native function.
|
||||
<pre>
|
||||
REG_NEWLINE
|
||||
</pre>
|
||||
The PCRE_MULTILINE option is set when the regular expression is passed for
|
||||
compilation to the native function. Note that this does <i>not</i> mimic the
|
||||
defined POSIX behaviour for REG_NEWLINE (see the following section).
|
||||
<pre>
|
||||
REG_NOSUB
|
||||
</pre>
|
||||
The PCRE_NO_AUTO_CAPTURE option is set when the regular expression is passed
|
||||
for compilation to the native function. In addition, when a pattern that is
|
||||
compiled with this flag is passed to <b>regexec()</b> for matching, the
|
||||
<i>nmatch</i> and <i>pmatch</i> arguments are ignored, and no captured strings
|
||||
are returned.
|
||||
<pre>
|
||||
REG_UCP
|
||||
</pre>
|
||||
The PCRE_UCP option is set when the regular expression is passed for
|
||||
compilation to the native function. This causes PCRE to use Unicode properties
|
||||
when matchine \d, \w, etc., instead of just recognizing ASCII values. Note
|
||||
that REG_UTF8 is not part of the POSIX standard.
|
||||
<pre>
|
||||
REG_UNGREEDY
|
||||
</pre>
|
||||
The PCRE_UNGREEDY option is set when the regular expression is passed for
|
||||
compilation to the native function. Note that REG_UNGREEDY is not part of the
|
||||
POSIX standard.
|
||||
<pre>
|
||||
REG_UTF8
|
||||
</pre>
|
||||
The PCRE_UTF8 option is set when the regular expression is passed for
|
||||
compilation to the native function. This causes the pattern itself and all data
|
||||
strings used for matching it to be treated as UTF-8 strings. Note that REG_UTF8
|
||||
is not part of the POSIX standard.
|
||||
</P>
|
||||
<P>
|
||||
In the absence of these flags, no options are passed to the native function.
|
||||
This means the the regex is compiled with PCRE default semantics. In
|
||||
particular, the way it handles newline characters in the subject string is the
|
||||
Perl way, not the POSIX way. Note that setting PCRE_MULTILINE has only
|
||||
<i>some</i> of the effects specified for REG_NEWLINE. It does not affect the way
|
||||
newlines are matched by . (they are not) or by a negative class such as [^a]
|
||||
(they are).
|
||||
</P>
|
||||
<P>
|
||||
The yield of <b>regcomp()</b> is zero on success, and non-zero otherwise. The
|
||||
<i>preg</i> structure is filled in on success, and one member of the structure
|
||||
is public: <i>re_nsub</i> contains the number of capturing subpatterns in
|
||||
the regular expression. Various error codes are defined in the header file.
|
||||
</P>
|
||||
<P>
|
||||
NOTE: If the yield of <b>regcomp()</b> is non-zero, you must not attempt to
|
||||
use the contents of the <i>preg</i> structure. If, for example, you pass it to
|
||||
<b>regexec()</b>, the result is undefined and your program is likely to crash.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">MATCHING NEWLINE CHARACTERS</a><br>
|
||||
<P>
|
||||
This area is not simple, because POSIX and Perl take different views of things.
|
||||
It is not possible to get PCRE to obey POSIX semantics, but then PCRE was never
|
||||
intended to be a POSIX engine. The following table lists the different
|
||||
possibilities for matching newline characters in PCRE:
|
||||
<pre>
|
||||
Default Change with
|
||||
|
||||
. matches newline no PCRE_DOTALL
|
||||
newline matches [^a] yes not changeable
|
||||
$ matches \n at end yes PCRE_DOLLARENDONLY
|
||||
$ matches \n in middle no PCRE_MULTILINE
|
||||
^ matches \n in middle no PCRE_MULTILINE
|
||||
</pre>
|
||||
This is the equivalent table for POSIX:
|
||||
<pre>
|
||||
Default Change with
|
||||
|
||||
. matches newline yes REG_NEWLINE
|
||||
newline matches [^a] yes REG_NEWLINE
|
||||
$ matches \n at end no REG_NEWLINE
|
||||
$ matches \n in middle no REG_NEWLINE
|
||||
^ matches \n in middle no REG_NEWLINE
|
||||
</pre>
|
||||
PCRE's behaviour is the same as Perl's, except that there is no equivalent for
|
||||
PCRE_DOLLAR_ENDONLY in Perl. In both PCRE and Perl, there is no way to stop
|
||||
newline from matching [^a].
|
||||
</P>
|
||||
<P>
|
||||
The default POSIX newline handling can be obtained by setting PCRE_DOTALL and
|
||||
PCRE_DOLLAR_ENDONLY, but there is no way to make PCRE behave exactly as for the
|
||||
REG_NEWLINE action.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">MATCHING A PATTERN</a><br>
|
||||
<P>
|
||||
The function <b>regexec()</b> is called to match a compiled pattern <i>preg</i>
|
||||
against a given <i>string</i>, which is by default terminated by a zero byte
|
||||
(but see REG_STARTEND below), subject to the options in <i>eflags</i>. These can
|
||||
be:
|
||||
<pre>
|
||||
REG_NOTBOL
|
||||
</pre>
|
||||
The PCRE_NOTBOL option is set when calling the underlying PCRE matching
|
||||
function.
|
||||
<pre>
|
||||
REG_NOTEMPTY
|
||||
</pre>
|
||||
The PCRE_NOTEMPTY option is set when calling the underlying PCRE matching
|
||||
function. Note that REG_NOTEMPTY is not part of the POSIX standard. However,
|
||||
setting this option can give more POSIX-like behaviour in some situations.
|
||||
<pre>
|
||||
REG_NOTEOL
|
||||
</pre>
|
||||
The PCRE_NOTEOL option is set when calling the underlying PCRE matching
|
||||
function.
|
||||
<pre>
|
||||
REG_STARTEND
|
||||
</pre>
|
||||
The string is considered to start at <i>string</i> + <i>pmatch[0].rm_so</i> and
|
||||
to have a terminating NUL located at <i>string</i> + <i>pmatch[0].rm_eo</i>
|
||||
(there need not actually be a NUL at that location), regardless of the value of
|
||||
<i>nmatch</i>. This is a BSD extension, compatible with but not specified by
|
||||
IEEE Standard 1003.2 (POSIX.2), and should be used with caution in software
|
||||
intended to be portable to other systems. Note that a non-zero <i>rm_so</i> does
|
||||
not imply REG_NOTBOL; REG_STARTEND affects only the location of the string, not
|
||||
how it is matched.
|
||||
</P>
|
||||
<P>
|
||||
If the pattern was compiled with the REG_NOSUB flag, no data about any matched
|
||||
strings is returned. The <i>nmatch</i> and <i>pmatch</i> arguments of
|
||||
<b>regexec()</b> are ignored.
|
||||
</P>
|
||||
<P>
|
||||
If the value of <i>nmatch</i> is zero, or if the value <i>pmatch</i> is NULL,
|
||||
no data about any matched strings is returned.
|
||||
</P>
|
||||
<P>
|
||||
Otherwise,the portion of the string that was matched, and also any captured
|
||||
substrings, are returned via the <i>pmatch</i> argument, which points to an
|
||||
array of <i>nmatch</i> structures of type <i>regmatch_t</i>, containing the
|
||||
members <i>rm_so</i> and <i>rm_eo</i>. These contain the offset to the first
|
||||
character of each substring and the offset to the first character after the end
|
||||
of each substring, respectively. The 0th element of the vector relates to the
|
||||
entire portion of <i>string</i> that was matched; subsequent elements relate to
|
||||
the capturing subpatterns of the regular expression. Unused entries in the
|
||||
array have both structure members set to -1.
|
||||
</P>
|
||||
<P>
|
||||
A successful match yields a zero return; various error codes are defined in the
|
||||
header file, of which REG_NOMATCH is the "expected" failure code.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">ERROR MESSAGES</a><br>
|
||||
<P>
|
||||
The <b>regerror()</b> function maps a non-zero errorcode from either
|
||||
<b>regcomp()</b> or <b>regexec()</b> to a printable message. If <i>preg</i> is not
|
||||
NULL, the error should have arisen from the use of that structure. A message
|
||||
terminated by a binary zero is placed in <i>errbuf</i>. The length of the
|
||||
message, including the zero, is limited to <i>errbuf_size</i>. The yield of the
|
||||
function is the size of buffer needed to hold the whole message.
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">MEMORY USAGE</a><br>
|
||||
<P>
|
||||
Compiling a regular expression causes memory to be allocated and associated
|
||||
with the <i>preg</i> structure. The function <b>regfree()</b> frees all such
|
||||
memory, after which <i>preg</i> may no longer be used as a compiled expression.
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC9" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 09 January 2012
|
||||
<br>
|
||||
Copyright © 1997-2012 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
Reference in New Issue
Block a user