.fp 5 B
.de Af
.ds ;G \\*(;G\\f\\$1\\$3\\f\\$2
.if !\\$4 .Af \\$2 \\$1 "\\$4" "\\$5" "\\$6" "\\$7" "\\$8" "\\$9"
..
.de aF
.ie \\$3 .ft \\$1
.el \{\
.ds ;G \&
.nr ;G \\n(.f
.Af "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7" "\\$8" "\\$9"
\\*(;G
.ft \\n(;G \}
..
.de L
.aF 5 \\n(.f "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7"
..
.de LR
.aF 5 1 "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7"
..
.de RL
.aF 1 5 "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7"
..
.de EX		\" start example
.ta 1i 2i 3i 4i 5i 6i
.PP
.RS 
.PD 0
.ft 5
.nf
..
.de EE		\" end example
.fi
.ft
.PD
.RE
.PP
..
.TH REGEX 3
.SH NAME
regex \- regular expression interface
.SH SYNOPSIS
.EX
#include <regex.h>

int        regcomp(regex_t* \fIre\fP, const char* \fIregex\fP, int \fIcflags\fP);
int        regexec(const regex_t* \fIre\fP, const char* \fIstring\fP, size_t \fInmatch\fP, regmatch_t \fIpmatch\fP[], int \fIeflags\fP);
size_t     regerror(int \fIcode\fP, const regex_t* \fIre\fP, char* \fIerrbuf\fP, size_t \fIerrbuf_size\fP);
void       regfree(regex_t* \fIre\fP);

regclass_t regclass(const char* \fIstr\fP, char** \fIend\fP);
int        regaddclass(const char* \fIname\fP, regclass_t \fIclassf\fP);
int        regcollate(const char* \fIstr\fP, char** \fIend\fP, char* \fIbuf\fP, int \fIsize\fP);

int        regcomb(regex_t* \fIre_1\fP, regex_t* \fIre_2\fP);
size_t     regdecomp(regex_t* \fIre\fP, regflags_t \fIflags\fP, char* \fIbuf\fP, size_t \fIsize\fP);
int        regdup(regex_t* \fIre_old\fP, regex_t* \fIre_new\fP);
regstat_t* regstat(const regex_t* \fIre\fP);

regex_t*   regcache(const char* \fIpattern\fP, regflags_t \fIflags\fP, int* \fIpcode\fP);

int        regncomp(regex_t* \fIre\fP, const char* \fIpattern\fP, size_t \fIsize\fP, regflags_t \fIflags\fP);
int        regnexec(const regex_t* \fIre\fP, const char* \fIsubject\fP, size_t \fIsize\fP, size_t \fInmatch\fP, regmatch_t* \fImatch\fP, regflags_t \fIflags\fP);
int        regrecord(const regex_t* \fIre\fP);
int        regrexec(const regex_t* \fIre\fP, const char* \fIbuf\fP, size_t \fIsize\fP, size_t \fInmatch\fP, regmatch_t* \fImatch\fP, regflags_t \fIflags\fP, int \fIsep\fP, void* \fIhandle\fP, regrecord_t \fIrecordf\fP);
void       regfatal(regex_t* \fIre\fP, int \fIlevel\fP, int \fIcode\fP);
void       regfatalpat(regex_t* \fIre\fP, int \fIlevel\fP, int \fIcode\fP, const char* \fIpattern\fP);

int        regsubcomp(regex_t* \fIre\fP, const char* \fIstr\fP, const regflags_t* \fImap\fP, int \fIminmatch\fP, regflags_t \fIflags\fP);
int        regsubexec(const regex_t* \fIre\fP, const char* \fIsubject\fP, size_t \fInmatch\fP, regmatch_t* match);
int        regsubflags(regex_t* \fIre\fP, const char* \fIstr\fP, char** \fIend\fP, int \fIdelim\fP, const regflags_t* \fImap\fP, int* \fIpm\fP, regflags_t* \fIpf\fP);
void       regsubfree(regex_t* \fIre\fP);
.EE

.SH DESCRIPTION
.LR regcomp() ,
.LR regexec() ,
.LR regerror() ,
and
.L regfree()
are the POSIX regular expression functions.
The remaining functions are
.B ast
extensions.
.B ast
also provides
.I flags
extensions to the
.LR regcomp() ,
.LR regexec()
functions and
.I code
extensions to the
.L regerror()
function.

.PP
.L regcache()
maintains a cache of compiled regular expressions for patterns of size
255 bytes or less.
The initial cache size is 8.
.L pattern
and
.L flags
are passed to
.L regcomp()
with an
.L re
pointer maintained by
.LR regcache() .
.LR pcode ,
if not 0, points to the return value of the
.L regcomp()
call.
If the
.L regcomp()
call fails,
.L regcache()
returns 0 and
.L pcode
will point to the non-zero error code.
Do not call
.L regfree()
on the
.L re
returned by
.LR regcache() .
Both
.L pattern
and
.L flags
are used to match entries in the cache.
When the cache is full the least recently used
.L re
is freed (via
.LR regfree() )
to make space for the new pattern.
Any
.L re
previously returned by
.L regcache()
may be freed (invalidated) on the next call to
.LR regcache() .
If
.L pattern
is longer that 255 bytes then it is still passed on to
.LR regcomp() ,
but it will not be cached.
If
.L pattern
is 0 then the cache is flushed.
In addition, if the integer value of
.L flags
is greater than the current cache size, the cache size is increased
to that integer value.
0 is always returned when
.L pattern
is 0;
.L pcode
will point to a non-zero value on error.

.SH "SEE ALSO"
strmatch(3)