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NAME
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regcomp, regcomplit, regcompnl, regexec, regsub, rregexec, rregsub,
regerror – regular expression
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SYNOPSIS
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#include <u.h>
#include <libc.h>
#include <regexp.h>
Reprog *regcomp(char *exp)
Reprog *regcomplit(char *exp)
Reprog *regcompnl(char *exp)
int regexec(Reprog *prog, char *string, Resub *match, int msize)
void regsub(char *source, char *dest, int dlen, Resub *match,
int msize)
int rregexec(Reprog *prog, Rune *string, Resub *match, int msize)
void rregsub(Rune *source, Rune *dest, int dlen, Resub *match,
int msize)
void regerror(char *msg)
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DESCRIPTION
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Regcomp compiles a regular expression and returns a pointer to
the generated description. The space is allocated by malloc(3)
and may be released by free. Regular expressions are exactly as
in regexp(7).
Regcomplit is like regcomp except that all characters are treated
literally. Regcompnl is like regcomp except that the . metacharacter
matches all characters, including newlines.
Regexec matches a null-terminated string against the compiled
regular expression in prog. If it matches, regexec returns 1 and
fills in the array match with character pointers to the substrings
of string that correspond to the parenthesized subexpressions
of exp: match[i].sp points to the beginning and match[i].ep points
just beyond the end of the
ith substring. (Subexpression i begins at the ith left parenthesis,
counting from 1.) Pointers in match[0] pick out the substring
that corresponds to the whole regular expression. Unused elements
of match are filled with zeros. Matches involving *, +, and ?
are extended as far as possible. The number of array elements
in match is given by msize.
The structure of elements of match is:
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typedef struct {
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union {
char *sp;
Rune *rsp;
} s;
union {
char *ep;
Rune *rep;
} e;
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} Resub;
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If match[0].s.sp is nonzero on entry, regexec starts matching
at that point within string. If match[0].e.ep is nonzero on entry,
the last character matched is the one preceding that point.
Regsub places in dest a substitution instance of source in the
context of the last regexec performed using match. Each instance
of \n, where n is a digit, is replaced by the string delimited
by match[n].sp and match[n].ep. Each instance of & is replaced
by the string delimited by match[0].sp and match[0].ep. The substitution
will always be
null terminated and trimmed to fit into dlen bytes.
Regerror, called whenever an error is detected in regcomp, writes
the string msg on the standard error file and exits. Regerror
can be replaced to perform special error processing. If the user
supplied regerror returns rather than exits, regcomp will return
0.
Rregexec and rregsub are variants of regexec and regsub that use
strings of Runes instead of strings of chars. With these routines,
the rsp and rep fields of the match array elements should be used.
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SOURCE
SEE ALSO
DIAGNOSTICS
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Regcomp returns 0 for an illegal expression or other failure.
Regexec returns 0 if string is not matched.
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BUGS
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There is no way to specify or match a NUL character; NULs terminate
patterns and strings.
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