Is there any way of avoiding the external module and catch an arbitrary
number of nested parentheses with a "normal" Regex?
use Regexp::Common;
$str =~ /$RE{balanced}{-parens=>'()'}/
| [reply] [d/l] |
| [reply] [d/l] |
Ah, sorry. Missed that bit.
How about:
use Regexp::Common;
print $RE{balanced}{-parens=>'()'}, "\n";
print $RE{balanced}{-parens=>'{}'}, "\n";
print $RE{balanced}{-parens=>'{}()'}, "\n";
# etc.
followed by reading the Regexp::Common source?
Damian
| [reply] [d/l] |
Thanks for the tip. I am not sure I understand how to use it, though.
My purpose, as you have pointed out, is to replace Regexp::Common with some normal Perl RegEx. By normal I mean a non-module dependant expression.
As for the motivation, you guessed right that it's related to education. Personally, I wouldn't bother. I need to distribute this module as part of a more extensive educational material aiming at the build-up of a huge database. I would like to avoid pointing to a CPAN module, since many people in the audience are not experienced Perl users. They should just copy this module to their computers and execute the import/export script.
Of course I can provide them with a copy of the module, or instruct them to connect to the CPAN, download the module and install it, or use "perl -MCPAN -e shell" but it would steal valuable time from my lectures.
That aside, here is a test script for your RegEx, which does not seem to give me what I want.
Was it my misunderstanding, or were you trying to show me how to catch the inner parenthesized text only?
#!/usr/bin/perl -w
use strict;
use Regexp::Common;
my $re = qr{ \( (?: (?> [^()]+ ) | (??{ $re }))* \) }x;
my $input = "aa bb cc (dd ee (ff gg (hh) jj) kk)";
print "With module\n";
while ($input =~ m/(\w+|$RE{balanced}{-parens=>'()'})\s*/g) {
print "$1\n";
}
print "With recursive RegExp\n";
while ($input =~ m/(\w+|$re)\s*/g) {
print "$1\n";
}
__END__
# output:
With module
aa
bb
cc
(dd ee (ff gg (hh) jj) kk)
With recursive RegExp
aa
bb
cc
dd
ee
ff
gg
(hh)
jj
kk
update
Found the problem. Recursive RegExes don't work properly with use strict
Changing
my $re = qr{ \( (?: (?> [^()]+ ) | (??{ $re }))* \) }x;
into
no strict 'vars';
$rec_re = qr{ \( (?: (?> [^()]+ ) | (??{ $rec_re }))* \) }x;
my $re = $rec_re;
use strict;
makes the same output from both regexes.
_ _ _ _
(_|| | |(_|><
_|
| [reply] [d/l] [select] |
| [reply] |
| [reply] [d/l] |