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Perl regex help - matching parentheses

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Top Forums Shell Programming and Scripting Perl regex help - matching parentheses
# 8  
Old 02-27-2009
The right answer here is in the perlre of modern perls:

Code:
                 The following pattern matches a parenthesized group:

                   $re = qr{
                              \(
                              (?:
                                 (?> [^()]+ )    # Non-parens without backtracking
                               |
                                 (??{ $re })     # Group with matching parens
                              )*
                              \)
                           }x;

Basically, (??{...}) embeds a regular expression (or a nested expression that chooses a regular expression) within another RE -- getting you recursive regular expressions.

If you have access to perl 5.10, you've got some other approaches available, as 5.10 has true recursive pattern matching without this kind of magic -- see here: perldelta - what is new for perl 5.10.0 - search.cpan.org
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LEARN ABOUT CENTOS

re_exec

RE_COMP(3)						     Linux Programmer's Manual							RE_COMP(3)

NAME

       re_comp, re_exec - BSD regex functions

SYNOPSIS

       #define _REGEX_RE_COMP
       #include <sys/types.h>
       #include <regex.h>

       char *re_comp(char *regex);

       int re_exec(char *string);

DESCRIPTION

       re_comp()  is used to compile the null-terminated regular expression pointed to by regex.  The compiled pattern occupies a static area, the
       pattern buffer, which is overwritten by subsequent use of re_comp().  If regex is NULL, no operation is performed and the pattern  buffer's
       contents are not altered.

       re_exec() is used to assess whether the null-terminated string pointed to by string matches the previously compiled regex.

RETURN VALUE

       re_comp() returns NULL on successful compilation of regex otherwise it returns a pointer to an appropriate error message.

       re_exec() returns 1 for a successful match, zero for failure.

ATTRIBUTES

   Multithreading (see pthreads(7))
       The re_comp() and re_exec() functions are not thread-safe.

CONFORMING TO

       4.3BSD.

NOTES

       These functions are obsolete; the functions documented in regcomp(3) should be used instead.

SEE ALSO

       regcomp(3), regex(7), GNU regex manual

COLOPHON

       This  page is part of release 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

GNU
								    2013-06-21								RE_COMP(3)