BSD 4_3_Net_2 release

[unix-history] / usr / src / lib / libc / gen / regexp.3

diff --git a/usr/src/lib/libc/gen/regexp.3 b/usr/src/lib/libc/gen/regexp.3
index cf3ef2e..c78082b 100644 (file)
--- a/usr/src/lib/libc/gen/regexp.3
+++ b/usr/src/lib/libc/gen/regexp.3
@@ -1,133 +1,235 @@
+.\" Copyright 1991 The Regents of the University of California.
+.\" All rights reserved.

 .\"
 .\"

-.\"    @(#)regexp.3    5.1 (Berkeley) 5/19/88
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"    This product includes software developed by the University of
+.\"    California, Berkeley and its contributors.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.

 .\"
 .\"

-.TH REGEXP 3 "May 19, 1988"
-.UC
-.SH NAME
-regcomp, regexec, regsub, regerror \- regular expression handlers
-.SH SYNOPSIS
-.nf
-.B #include <regexp.h>
-.PP
-.B regexp *regcomp(exp)
-.B char *exp;
-.PP
-.B int regexec(prog, string)
-.B regexp *prog;
-.B char *string;
-.PP
-.B regsub(prog, source, dest)
-.B regexp *prog;
-.B char *source;
-.B char *dest;
-.PP
-.B regerror(msg)
-.B char *msg;
-.fi
-.SH NAME
-\fIRegcomp\fP, \fIregexec\fP, \fIregsub\fP, and \fIregerror\fP implement
-.IR egrep (1)-style
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"     @(#)regexp.3   5.2 (Berkeley) 4/19/91
+.\"
+.Dd April 19, 1991
+.Dt REGEXP 3
+.Os
+.Sh NAME
+.Nm regcomp ,
+.Nm regexec ,
+.Nm regsub ,
+.Nm regerror
+.Nd regular expression handlers
+.Sh SYNOPSIS
+.Fd #include <regexp.h>
+.Ft regexp *
+.Fn regcomp "const char *exp"
+.Ft int
+.Fn regexec "const regexp *prog" "const char *string"
+.Ft void
+.Fn regsub "const regexp *prog" "const char *source" "char *dest"
+.Sh DESCRIPTION
+The
+.Fn regcomp ,
+.Fn regexec ,
+.Fn regsub ,
+and
+.Fn regerror
+functions
+implement
+.Xr egrep 1 Ns -style

 regular expressions and supporting facilities.
 regular expressions and supporting facilities.

-.PP
-.I Regcomp
+.Pp
+The
+.Fn regcomp
+function

 compiles a regular expression into a structure of type
 compiles a regular expression into a structure of type

-.IR regexp ,
+.Xr regexp ,

 and returns a pointer to it.
 The space has been allocated using
 and returns a pointer to it.
 The space has been allocated using

-.IR malloc (3)
+.Xr malloc 3

 and may be released by
 and may be released by

-.IR free .
-.PP
-.I Regexec
-matches a NUL-terminated \fIstring\fR against the compiled regular expression
-in \fIprog\fR.
+.Xr free .
+.Pp
+The
+.Fn regexec
+function
+matches a
+.Dv NUL Ns -terminated
+.Fa string
+against the compiled regular expression
+in
+.Fa prog .

 It returns 1 for success and 0 for failure, and adjusts the contents of
 It returns 1 for success and 0 for failure, and adjusts the contents of

-\fIprog\fR's \fIstartp\fR and \fIendp\fR (see below) accordingly.
-.PP
+.Fa prog Ns 's
+.Em startp
+and
+.Em endp
+(see below) accordingly.
+.Pp

 The members of a
 The members of a

-.I regexp
+.Xr regexp

 structure include at least the following (not necessarily in order):
 structure include at least the following (not necessarily in order):

-.PP
-.RS
+.Bd -literal -offset indent

 char *startp[NSUBEXP];
 char *startp[NSUBEXP];

-.br

 char *endp[NSUBEXP];
 char *endp[NSUBEXP];

-.RE
-.PP
+.Ed
+.Pp

 where
 where

-.I NSUBEXP
+.Dv NSUBEXP

 is defined (as 10) in the header file.
 is defined (as 10) in the header file.

-Once a successful \fIregexec\fR has been done using the \fIregexp\fR,
-each \fIstartp\fR-\fIendp\fR pair describes one substring
-within the \fIstring\fR,
-with the \fIstartp\fR pointing to the first character of the substring and
-the \fIendp\fR pointing to the first character following the substring.
-The 0th substring is the substring of \fIstring\fR that matched the whole
+Once a successful
+.Fn regexec
+has been done using the
+.Fn regexp ,
+each
+.Em startp Ns - Em endp
+pair describes one substring
+within the
+.Fa string ,
+with the
+.Em startp
+pointing to the first character of the substring and
+the
+.Em endp
+pointing to the first character following the substring.
+The 0th substring is the substring of
+.Fa string
+that matched the whole

 regular expression.
 The others are those substrings that matched parenthesized expressions
 within the regular expression, with parenthesized expressions numbered
 in left-to-right order of their opening parentheses.
 regular expression.
 The others are those substrings that matched parenthesized expressions
 within the regular expression, with parenthesized expressions numbered
 in left-to-right order of their opening parentheses.

-.PP
-.I Regsub
-copies \fIsource\fR to \fIdest\fR, making substitutions according to the
-most recent \fIregexec\fR performed using \fIprog\fR.
-Each instance of `&' in \fIsource\fR is replaced by the substring
-indicated by \fIstartp\fR[\fI0\fR] and
-\fIendp\fR[\fI0\fR].
-Each instance of `\e\fIn\fR', where \fIn\fR is a digit, is replaced by
+.Pp
+The
+.Fn regsub
+function
+copies
+.Fa source
+to
+.Fa dest ,
+making substitutions according to the
+most recent
+.Fn regexec
+performed using
+.Fa prog .
+Each instance of `&' in
+.Fa source
+is replaced by the substring
+indicated by
+.Em startp Ns Bq
+and
+.Em endp Ns Bq .
+Each instance of
+.Sq \e Ns Em n ,
+where
+.Em n
+is a digit, is replaced by

 the substring indicated by
 the substring indicated by

-\fIstartp\fR[\fIn\fR] and
-\fIendp\fR[\fIn\fR].
-To get a literal `&' or `\e\fIn\fR' into \fIdest\fR, prefix it with `\e';
-to get a literal `\e' preceding `&' or `\e\fIn\fR', prefix it with
+.Em startp Ns Bq Em n
+and
+.Em endp Ns Bq Em n .
+To get a literal `&' or
+.Sq \e Ns Em n
+into
+.Fa dest ,
+prefix it with `\e';
+to get a literal `\e' preceding `&' or
+.Sq \e Ns Em n ,
+prefix it with

 another `\e'.
 another `\e'.

-.PP
-.I Regerror
-is called whenever an error is detected in \fIregcomp\fR, \fIregexec\fR,
-or \fIregsub\fR.
-The default \fIregerror\fR writes the string \fImsg\fR,
+.Pp
+The
+.Fn regerror
+function
+is called whenever an error is detected in
+.Fn regcomp ,
+.Fn regexec ,
+or
+.Fn regsub .
+The default
+.Fn regerror
+writes the string
+.Fa msg ,

 with a suitable indicator of origin,
 on the standard
 error output
 with a suitable indicator of origin,
 on the standard
 error output

-and invokes \fIexit\fR(2).
-.I Regerror
+and invokes
+.Xr exit 2 .
+The
+.Fn regerror
+function

 can be replaced by the user if other actions are desirable.
 can be replaced by the user if other actions are desirable.

-.SH "REGULAR EXPRESSION SYNTAX"
-A regular expression is zero or more \fIbranches\fR, separated by `|'.
+.Sh REGULAR EXPRESSION SYNTAX
+A regular expression is zero or more
+.Em branches ,
+separated by `|'.

 It matches anything that matches one of the branches.
 It matches anything that matches one of the branches.

-.PP
-A branch is zero or more \fIpieces\fR, concatenated.
+.Pp
+A branch is zero or more
+.Em pieces ,
+concatenated.

 It matches a match for the first, followed by a match for the second, etc.
 It matches a match for the first, followed by a match for the second, etc.

-.PP
-A piece is an \fIatom\fR possibly followed by `*', `+', or `?'.
+.Pp
+A piece is an
+.Em atom
+possibly followed by `*', `+', or `?'.

 An atom followed by `*' matches a sequence of 0 or more matches of the atom.
 An atom followed by `+' matches a sequence of 1 or more matches of the atom.
 An atom followed by `?' matches a match of the atom, or the null string.
 An atom followed by `*' matches a sequence of 0 or more matches of the atom.
 An atom followed by `+' matches a sequence of 1 or more matches of the atom.
 An atom followed by `?' matches a match of the atom, or the null string.

-.PP
+.Pp

 An atom is a regular expression in parentheses (matching a match for the
 An atom is a regular expression in parentheses (matching a match for the

-regular expression), a \fIrange\fR (see below), `.'
+regular expression), a
+.Em range
+(see below), `.'

 (matching any single character), `^' (matching the null string at the
 beginning of the input string), `$' (matching the null string at the
 end of the input string), a `\e' followed by a single character (matching
 that character), or a single character with no other significance
 (matching that character).
 (matching any single character), `^' (matching the null string at the
 beginning of the input string), `$' (matching the null string at the
 end of the input string), a `\e' followed by a single character (matching
 that character), or a single character with no other significance
 (matching that character).

-.PP
-A \fIrange\fR is a sequence of characters enclosed in `[]'.
+.Pp
+A
+.Em range
+is a sequence of characters enclosed in `[]'.

 It normally matches any single character from the sequence.
 If the sequence begins with `^',
 It normally matches any single character from the sequence.
 If the sequence begins with `^',

-it matches any single character \fInot\fR from the rest of the sequence.
+it matches any single character
+.Em not
+from the rest of the sequence.

 If two characters in the sequence are separated by `\-', this is shorthand
 If two characters in the sequence are separated by `\-', this is shorthand

-for the full list of ASCII characters between them
+for the full list of
+.Tn ASCII
+characters between them

 (e.g. `[0-9]' matches any decimal digit).
 To include a literal `]' in the sequence, make it the first character
 (following a possible `^').
 To include a literal `\-', make it the first or last character.
 (e.g. `[0-9]' matches any decimal digit).
 To include a literal `]' in the sequence, make it the first character
 (following a possible `^').
 To include a literal `\-', make it the first or last character.

-.SH AMBIGUITY
+.Sh AMBIGUITY

 If a regular expression could match two different parts of the input string,
 it will match the one which begins earliest.
 If both begin in the same place but match different lengths, or match
 the same length in different ways, life gets messier, as follows.
 If a regular expression could match two different parts of the input string,
 it will match the one which begins earliest.
 If both begin in the same place but match different lengths, or match
 the same length in different ways, life gets messier, as follows.

-.PP
+.Pp

 In general, the possibilities in a list of branches are considered in
 left-to-right order, the possibilities for `*', `+', and `?' are
 considered longest-first, nested constructs are considered from the
 In general, the possibilities in a list of branches are considered in
 left-to-right order, the possibilities for `*', `+', and `?' are
 considered longest-first, nested constructs are considered from the


@@ -137,46 +239,77 @@ possibility in the first choice that has to be made.
 If there is more than one choice, the next will be made in the same manner
 (earliest possibility) subject to the decision on the first choice.
 And so forth.
 If there is more than one choice, the next will be made in the same manner
 (earliest possibility) subject to the decision on the first choice.
 And so forth.

-.PP
-For example, `(ab|a)b*c' could match `abc' in one of two ways.
+.Pp
+For example,
+.Sq Li (ab|a)b*c
+could match
+`abc' in one of two ways.

 The first choice is between `ab' and `a'; since `ab' is earlier, and does
 lead to a successful overall match, it is chosen.
 Since the `b' is already spoken for,
 the `b*' must match its last possibility\(emthe empty string\(emsince
 it must respect the earlier choice.
 The first choice is between `ab' and `a'; since `ab' is earlier, and does
 lead to a successful overall match, it is chosen.
 Since the `b' is already spoken for,
 the `b*' must match its last possibility\(emthe empty string\(emsince
 it must respect the earlier choice.

-.PP
+.Pp

 In the particular case where no `|'s are present and there is only one
 `*', `+', or `?', the net effect is that the longest possible
 match will be chosen.
 In the particular case where no `|'s are present and there is only one
 `*', `+', or `?', the net effect is that the longest possible
 match will be chosen.

-So `ab*', presented with `xabbbby', will match `abbbb'.
-Note that if `ab*' is tried against `xabyabbbz', it
+So
+.Sq Li ab* ,
+presented with `xabbbby', will match `abbbb'.
+Note that if
+.Sq Li ab* ,
+is tried against `xabyabbbz', it

 will match `ab' just after `x', due to the begins-earliest rule.
 (In effect, the decision on where to start the match is the first choice
 to be made, hence subsequent choices must respect it even if this leads them
 to less-preferred alternatives.)
 will match `ab' just after `x', due to the begins-earliest rule.
 (In effect, the decision on where to start the match is the first choice
 to be made, hence subsequent choices must respect it even if this leads them
 to less-preferred alternatives.)

-.SH DIAGNOSTICS
-\fIRegcomp\fR returns NULL for a failure
-(\fIregerror\fR permitting),
+.Sh RETURN VALUES
+The
+.Fn regcomp
+function
+returns
+.Dv NULL
+for a failure
+.Pf ( Fn regerror
+permitting),

 where failures are syntax errors, exceeding implementation limits,
 or applying `+' or `*' to a possibly-null operand.
 where failures are syntax errors, exceeding implementation limits,
 or applying `+' or `*' to a possibly-null operand.

-.SH HISTORY
-Both code and manual page for \fIregcomp\fP, \fIregexec\fP, \fIregsub\fP,
-and \fIregerror\fP were written at the University of Toronto.
-They are intended to be compatible with the Bell V8 \fIregexp\fR(3),
+.Sh SEE ALSO
+.Xr ed 1 ,
+.Xr ex 1 ,
+.Xr expr 1 ,
+.Xr egrep 1 ,
+.Xr fgrep 1 ,
+.Xr grep 1 ,
+.Xr regex 3
+.Sh HISTORY
+Both code and manual page for
+.Fn regcomp ,
+.Fn regexec ,
+.Fn regsub ,
+and
+.Fn regerror
+were written at the University of Toronto
+and appeared in
+.Bx 4.3 tahoe .
+They are intended to be compatible with the Bell V8
+.Xr regexp 3 ,

 but are not derived from Bell code.
 but are not derived from Bell code.

-.SH BUGS
+.Sh BUGS

 Empty branches and empty regular expressions are not portable to V8.
 Empty branches and empty regular expressions are not portable to V8.

-.PP
+.Pp

 The restriction against
 applying `*' or `+' to a possibly-null operand is an artifact of the
 simplistic implementation.
 The restriction against
 applying `*' or `+' to a possibly-null operand is an artifact of the
 simplistic implementation.

-.PP
-Does not support \fIegrep\fR's newline-separated branches;
-neither does the V8 \fIregexp\fR(3), though.
-.PP
+.Pp
+Does not support
+.Xr egrep Ns 's
+newline-separated branches;
+neither does the V8
+.Xr regexp 3 ,
+though.
+.Pp

 Due to emphasis on
 compactness and simplicity,
 it's not strikingly fast.
 It does give special attention to handling simple cases quickly.
 Due to emphasis on
 compactness and simplicity,
 it's not strikingly fast.
 It does give special attention to handling simple cases quickly.

-.SH "SEE ALSO"
-ed(1), ex(1), expr(1), egrep(1), fgrep(1), grep(1), regex(3)