+++ /dev/null
-.TH PCREPOSIX 3
-.SH NAME
-PCRE - Perl-compatible regular expressions.
-.SH "SYNOPSIS OF POSIX API"
-.rs
-.sp
-.B #include <pcreposix.h>
-.PP
-.SM
-.B int regcomp(regex_t *\fIpreg\fP, const char *\fIpattern\fP,
-.ti +5n
-.B int \fIcflags\fP);
-.PP
-.B int regexec(regex_t *\fIpreg\fP, const char *\fIstring\fP,
-.ti +5n
-.B size_t \fInmatch\fP, regmatch_t \fIpmatch\fP[], int \fIeflags\fP);
-.PP
-.B size_t regerror(int \fIerrcode\fP, const regex_t *\fIpreg\fP,
-.ti +5n
-.B char *\fIerrbuf\fP, size_t \fIerrbuf_size\fP);
-.PP
-.B void regfree(regex_t *\fIpreg\fP);
-.
-.SH DESCRIPTION
-.rs
-.sp
-This set of functions provides a POSIX-style API to the PCRE regular expression
-package. See the
-.\" HREF
-\fBpcreapi\fP
-.\"
-documentation for a description of PCRE's native API, which contains much
-additional functionality.
-.P
-The functions described here are just wrapper functions that ultimately call
-the PCRE native API. Their prototypes are defined in the \fBpcreposix.h\fP
-header file, and on Unix systems the library itself is called
-\fBpcreposix.a\fP, so can be accessed by adding \fB-lpcreposix\fP to the
-command for linking an application that uses them. Because the POSIX functions
-call the native ones, it is also necessary to add \fB-lpcre\fP.
-.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
-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
-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
-The header for these functions is supplied as \fBpcreposix.h\fP to avoid any
-potential clash with other POSIX libraries. It can, of course, be renamed or
-aliased as \fBregex.h\fP, which is the "correct" name. It provides two
-structure types, \fIregex_t\fP for compiled internal forms, and
-\fIregmatch_t\fP 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
-.SH "COMPILING A PATTERN"
-.rs
-.sp
-The function \fBregcomp()\fP 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 \fIpattern\fP. The \fIpreg\fP argument is a pointer
-to a \fBregex_t\fP structure that is used as a base for storing information
-about the compiled regular expression.
-.P
-The argument \fIcflags\fP is either zero, or contains one or more of the bits
-defined by the following macros:
-.sp
- REG_DOTALL
-.sp
-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.
-.sp
- REG_ICASE
-.sp
-The PCRE_CASELESS option is set when the regular expression is passed for
-compilation to the native function.
-.sp
- REG_NEWLINE
-.sp
-The PCRE_MULTILINE option is set when the regular expression is passed for
-compilation to the native function. Note that this does \fInot\fP mimic the
-defined POSIX behaviour for REG_NEWLINE (see the following section).
-.sp
- REG_NOSUB
-.sp
-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 \fBregexec()\fP for matching, the
-\fInmatch\fP and \fIpmatch\fP arguments are ignored, and no captured strings
-are returned.
-.sp
- REG_UNGREEDY
-.sp
-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.
-.sp
- REG_UTF8
-.sp
-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
-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
-\fIsome\fP 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
-The yield of \fBregcomp()\fP is zero on success, and non-zero otherwise. The
-\fIpreg\fP structure is filled in on success, and one member of the structure
-is public: \fIre_nsub\fP contains the number of capturing subpatterns in
-the regular expression. Various error codes are defined in the header file.
-.P
-NOTE: If the yield of \fBregcomp()\fP is non-zero, you must not attempt to
-use the contents of the \fIpreg\fP structure. If, for example, you pass it to
-\fBregexec()\fP, the result is undefined and your program is likely to crash.
-.
-.
-.SH "MATCHING NEWLINE CHARACTERS"
-.rs
-.sp
-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:
-.sp
- Default Change with
-.sp
- . matches newline no PCRE_DOTALL
- newline matches [^a] yes not changeable
- $ matches \en at end yes PCRE_DOLLARENDONLY
- $ matches \en in middle no PCRE_MULTILINE
- ^ matches \en in middle no PCRE_MULTILINE
-.sp
-This is the equivalent table for POSIX:
-.sp
- Default Change with
-.sp
- . matches newline yes REG_NEWLINE
- newline matches [^a] yes REG_NEWLINE
- $ matches \en at end no REG_NEWLINE
- $ matches \en in middle no REG_NEWLINE
- ^ matches \en in middle no REG_NEWLINE
-.sp
-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
-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.
-.
-.
-.SH "MATCHING A PATTERN"
-.rs
-.sp
-The function \fBregexec()\fP is called to match a compiled pattern \fIpreg\fP
-against a given \fIstring\fP, which is by default terminated by a zero byte
-(but see REG_STARTEND below), subject to the options in \fIeflags\fP. These can
-be:
-.sp
- REG_NOTBOL
-.sp
-The PCRE_NOTBOL option is set when calling the underlying PCRE matching
-function.
-.sp
- REG_NOTEMPTY
-.sp
-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.
-.sp
- REG_NOTEOL
-.sp
-The PCRE_NOTEOL option is set when calling the underlying PCRE matching
-function.
-.sp
- REG_STARTEND
-.sp
-The string is considered to start at \fIstring\fP + \fIpmatch[0].rm_so\fP and
-to have a terminating NUL located at \fIstring\fP + \fIpmatch[0].rm_eo\fP
-(there need not actually be a NUL at that location), regardless of the value of
-\fInmatch\fP. 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 \fIrm_so\fP does
-not imply REG_NOTBOL; REG_STARTEND affects only the location of the string, not
-how it is matched.
-.P
-If the pattern was compiled with the REG_NOSUB flag, no data about any matched
-strings is returned. The \fInmatch\fP and \fIpmatch\fP arguments of
-\fBregexec()\fP are ignored.
-.P
-If the value of \fInmatch\fP is zero, or if the value \fIpmatch\fP is NULL,
-no data about any matched strings is returned.
-.P
-Otherwise,the portion of the string that was matched, and also any captured
-substrings, are returned via the \fIpmatch\fP argument, which points to an
-array of \fInmatch\fP structures of type \fIregmatch_t\fP, containing the
-members \fIrm_so\fP and \fIrm_eo\fP. 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 \fIstring\fP 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
-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.
-.
-.
-.SH "ERROR MESSAGES"
-.rs
-.sp
-The \fBregerror()\fP function maps a non-zero errorcode from either
-\fBregcomp()\fP or \fBregexec()\fP to a printable message. If \fIpreg\fP is not
-NULL, the error should have arisen from the use of that structure. A message
-terminated by a binary zero is placed in \fIerrbuf\fP. The length of the
-message, including the zero, is limited to \fIerrbuf_size\fP. The yield of the
-function is the size of buffer needed to hold the whole message.
-.
-.
-.SH MEMORY USAGE
-.rs
-.sp
-Compiling a regular expression causes memory to be allocated and associated
-with the \fIpreg\fP structure. The function \fBregfree()\fP frees all such
-memory, after which \fIpreg\fP may no longer be used as a compiled expression.
-.
-.
-.SH AUTHOR
-.rs
-.sp
-.nf
-Philip Hazel
-University Computing Service
-Cambridge CB2 3QH, England.
-.fi
-.
-.
-.SH REVISION
-.rs
-.sp
-.nf
-Last updated: 02 September 2009
-Copyright (c) 1997-2009 University of Cambridge.
-.fi
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