trunk/doc/pcreposix.html

<HTML>
<HEAD>
<TITLE>pcreposix specification</TITLE>
</HEAD>
<body bgcolor="#FFFFFF" text="#00005A">
<H1>pcreposix specification</H1>
This HTML document has been 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.
<UL>
<LI><A NAME="TOC1" HREF="#SEC1">NAME</A>
<LI><A NAME="TOC2" HREF="#SEC2">SYNOPSIS</A>
<LI><A NAME="TOC3" HREF="#SEC3">DESCRIPTION</A>
<LI><A NAME="TOC4" HREF="#SEC4">COMPILING A PATTERN</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">STORAGE</A>
<LI><A NAME="TOC8" HREF="#SEC8">AUTHOR</A>
</UL>
<LI><A NAME="SEC1" HREF="#TOC1">NAME</A>
<P>
pcreposix - POSIX API for Perl-compatible regular expressions.
</P>
<LI><A NAME="SEC2" HREF="#TOC1">SYNOPSIS</A>
<P>
<B>#include &#60;pcreposix.h&#62;</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>
<LI><A NAME="SEC3" HREF="#TOC1">DESCRIPTION</A>
<P>
This set of functions provides a POSIX-style API to the PCRE regular expression
package. See the <B>pcre</B> documentation for a description of the native API,
which contains additional functionality.
</P>
<P>
The functions described here are just wrapper functions that ultimately call
the 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 which uses them. Because the POSIX functions call the native ones,
it is also necessary to add \fR-lpcre\fR.
</P>
<P>
As I am pretty ignorant about POSIX, these functions must be considered as
experimental. I have implemented only those option bits that can be reasonably
mapped to PCRE native options. Other POSIX options are not even defined. It may
be that it is useful to define, but ignore, other options. Feedback from more
knowledgeable folk may cause this kind of detail to change.
</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.
</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>
<LI><A NAME="SEC4" HREF="#TOC1">COMPILING A PATTERN</A>
<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 regex_t structure which is used as a base for storing information about
the compiled expression.
</P>
<P>
The argument <I>cflags</I> is either zero, or contains one or more of the bits
defined by the following macros:
</P>
<P>
<PRE>
  REG_ICASE
</PRE>
</P>
<P>
The PCRE_CASELESS option is set when the expression is passed for compilation
to the native function.
</P>
<P>
<PRE>
  REG_NEWLINE
</PRE>
</P>
<P>
The PCRE_MULTILINE option is set when the expression is passed for compilation
to the native function.
</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 publicized: <I>re_nsub</I> contains the number of capturing subpatterns in
the regular expression. Various error codes are defined in the header file.
</P>
<LI><A NAME="SEC5" HREF="#TOC1">MATCHING A PATTERN</A>
<P>
The function <B>regexec()</B> is called to match a pre-compiled pattern
<I>preg</I> against a given <I>string</I>, which is terminated by a zero byte,
subject to the options in <I>eflags</I>. These can be:
</P>
<P>
<PRE>
  REG_NOTBOL
</PRE>
</P>
<P>
The PCRE_NOTBOL option is set when calling the underlying PCRE matching
function.
</P>
<P>
<PRE>
  REG_NOTEOL
</PRE>
</P>
<P>
The PCRE_NOTEOL option is set when calling the underlying PCRE matching
function.
</P>
<P>
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>
<LI><A NAME="SEC6" HREF="#TOC1">ERROR MESSAGES</A>
<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>
<LI><A NAME="SEC7" HREF="#TOC1">STORAGE</A>
<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>
<LI><A NAME="SEC8" HREF="#TOC1">AUTHOR</A>
<P>
Philip Hazel &#60;ph10@cam.ac.uk&#62;
<BR>
University Computing Service,
<BR>
New Museums Site,
<BR>
Cambridge CB2 3QG, England.
<BR>
Phone: +44 1223 334714
</P>
<P>
Copyright (c) 1997-1999 University of Cambridge.
1	nigel	41	<HTML>
2			<HEAD>
3			<TITLE>pcreposix specification</TITLE>
4			</HEAD>
5			<body bgcolor="#FFFFFF" text="#00005A">
6			<H1>pcreposix specification</H1>
7			This HTML document has been generated automatically from the original man page.
8			If there is any nonsense in it, please consult the man page in case the
9			conversion went wrong.
10			<UL>
11			<LI><A NAME="TOC1" HREF="#SEC1">NAME</A>
12			<LI><A NAME="TOC2" HREF="#SEC2">SYNOPSIS</A>
13			<LI><A NAME="TOC3" HREF="#SEC3">DESCRIPTION</A>
14			<LI><A NAME="TOC4" HREF="#SEC4">COMPILING A PATTERN</A>
15			<LI><A NAME="TOC5" HREF="#SEC5">MATCHING A PATTERN</A>
16			<LI><A NAME="TOC6" HREF="#SEC6">ERROR MESSAGES</A>
17			<LI><A NAME="TOC7" HREF="#SEC7">STORAGE</A>
18			<LI><A NAME="TOC8" HREF="#SEC8">AUTHOR</A>
19			</UL>
20			<LI><A NAME="SEC1" HREF="#TOC1">NAME</A>
21			<P>
22			pcreposix - POSIX API for Perl-compatible regular expressions.
23			</P>
24			<LI><A NAME="SEC2" HREF="#TOC1">SYNOPSIS</A>
25			<P>
26			<B>#include <pcreposix.h></B>
27			</P>
28			<P>
29			<B>int regcomp(regex_t <I>preg</I>, const char <I>pattern</I>,</B>
30			<B>int <I>cflags</I>);</B>
31			</P>
32			<P>
33			<B>int regexec(regex_t <I>preg</I>, const char <I>string</I>,</B>
34			<B>size_t <I>nmatch</I>, regmatch_t <I>pmatch</I>[], int <I>eflags</I>);</B>
35			</P>
36			<P>
37			<B>size_t regerror(int <I>errcode</I>, const regex_t *<I>preg</I>,</B>
38			<B>char *<I>errbuf</I>, size_t <I>errbuf_size</I>);</B>
39			</P>
40			<P>
41			<B>void regfree(regex_t *<I>preg</I>);</B>
42			</P>
43			<LI><A NAME="SEC3" HREF="#TOC1">DESCRIPTION</A>
44			<P>
45			This set of functions provides a POSIX-style API to the PCRE regular expression
46			package. See the <B>pcre</B> documentation for a description of the native API,
47			which contains additional functionality.
48			</P>
49			<P>
50			The functions described here are just wrapper functions that ultimately call
51			the native API. Their prototypes are defined in the <B>pcreposix.h</B> header
52			file, and on Unix systems the library itself is called <B>pcreposix.a</B>, so
53			can be accessed by adding <B>-lpcreposix</B> to the command for linking an
54			application which uses them. Because the POSIX functions call the native ones,
55			it is also necessary to add \fR-lpcre\fR.
56			</P>
57			<P>
58			As I am pretty ignorant about POSIX, these functions must be considered as
59			experimental. I have implemented only those option bits that can be reasonably
60			mapped to PCRE native options. Other POSIX options are not even defined. It may
61			be that it is useful to define, but ignore, other options. Feedback from more
62			knowledgeable folk may cause this kind of detail to change.
63			</P>
64			<P>
65			When PCRE is called via these functions, it is only the API that is POSIX-like
66			in style. The syntax and semantics of the regular expressions themselves are
67			still those of Perl, subject to the setting of various PCRE options, as
68			described below.
69			</P>
70			<P>
71			The header for these functions is supplied as <B>pcreposix.h</B> to avoid any
72			potential clash with other POSIX libraries. It can, of course, be renamed or
73			aliased as <B>regex.h</B>, which is the "correct" name. It provides two
74			structure types, <I>regex_t</I> for compiled internal forms, and
75			<I>regmatch_t</I> for returning captured substrings. It also defines some
76			constants whose names start with "REG_"; these are used for setting options and
77			identifying error codes.
78			</P>
79			<LI><A NAME="SEC4" HREF="#TOC1">COMPILING A PATTERN</A>
80			<P>
81			The function <B>regcomp()</B> is called to compile a pattern into an
82			internal form. The pattern is a C string terminated by a binary zero, and
83			is passed in the argument <I>pattern</I>. The <I>preg</I> argument is a pointer
84			to a regex_t structure which is used as a base for storing information about
85			the compiled expression.
86			</P>
87			<P>
88			The argument <I>cflags</I> is either zero, or contains one or more of the bits
89			defined by the following macros:
90			</P>
91			<P>
92			<PRE>
93			REG_ICASE
94			</PRE>
95			</P>
96			<P>
97			The PCRE_CASELESS option is set when the expression is passed for compilation
98			to the native function.
99			</P>
100			<P>
101			<PRE>
102			REG_NEWLINE
103			</PRE>
104			</P>
105			<P>
106			The PCRE_MULTILINE option is set when the expression is passed for compilation
107			to the native function.
108			</P>
109			<P>
110			The yield of <B>regcomp()</B> is zero on success, and non-zero otherwise. The
111			<I>preg</I> structure is filled in on success, and one member of the structure
112			is publicized: <I>re_nsub</I> contains the number of capturing subpatterns in
113			the regular expression. Various error codes are defined in the header file.
114			</P>
115			<LI><A NAME="SEC5" HREF="#TOC1">MATCHING A PATTERN</A>
116			<P>
117			The function <B>regexec()</B> is called to match a pre-compiled pattern
118			<I>preg</I> against a given <I>string</I>, which is terminated by a zero byte,
119			subject to the options in <I>eflags</I>. These can be:
120			</P>
121			<P>
122			<PRE>
123			REG_NOTBOL
124			</PRE>
125			</P>
126			<P>
127			The PCRE_NOTBOL option is set when calling the underlying PCRE matching
128			function.
129			</P>
130			<P>
131			<PRE>
132			REG_NOTEOL
133			</PRE>
134			</P>
135			<P>
136			The PCRE_NOTEOL option is set when calling the underlying PCRE matching
137			function.
138			</P>
139			<P>
140			The portion of the string that was matched, and also any captured substrings,
141			are returned via the <I>pmatch</I> argument, which points to an array of
142			<I>nmatch</I> structures of type <I>regmatch_t</I>, containing the members
143			<I>rm_so</I> and <I>rm_eo</I>. These contain the offset to the first character of
144			each substring and the offset to the first character after the end of each
145			substring, respectively. The 0th element of the vector relates to the entire
146			portion of <I>string</I> that was matched; subsequent elements relate to the
147			capturing subpatterns of the regular expression. Unused entries in the array
148			have both structure members set to -1.
149			</P>
150			<P>
151			A successful match yields a zero return; various error codes are defined in the
152			header file, of which REG_NOMATCH is the "expected" failure code.
153			</P>
154			<LI><A NAME="SEC6" HREF="#TOC1">ERROR MESSAGES</A>
155			<P>
156			The <B>regerror()</B> function maps a non-zero errorcode from either
157			<B>regcomp</B> or <B>regexec</B> to a printable message. If <I>preg</I> is not
158			NULL, the error should have arisen from the use of that structure. A message
159			terminated by a binary zero is placed in <I>errbuf</I>. The length of the
160			message, including the zero, is limited to <I>errbuf_size</I>. The yield of the
161			function is the size of buffer needed to hold the whole message.
162			</P>
163			<LI><A NAME="SEC7" HREF="#TOC1">STORAGE</A>
164			<P>
165			Compiling a regular expression causes memory to be allocated and associated
166			with the <I>preg</I> structure. The function <B>regfree()</B> frees all such
167			memory, after which <I>preg</I> may no longer be used as a compiled expression.
168			</P>
169			<LI><A NAME="SEC8" HREF="#TOC1">AUTHOR</A>
170			<P>
171			Philip Hazel <ph10@cam.ac.uk>
172			<BR>
173			University Computing Service,
174			<BR>
175			New Museums Site,
176			<BR>
177			Cambridge CB2 3QG, England.
178			<BR>
179			Phone: +44 1223 334714
180			</P>
181			<P>
182			Copyright (c) 1997-1999 University of Cambridge.