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Think about Loose Coupling

Re: Split a sentence into words

by ikegami (Pope)
on May 30, 2009 at 07:05 UTC ( #767014=note: print w/replies, xml ) Need Help??

in reply to Split a sentence into words

Don't use my variables declared outside the regex pattern from within (?{}).

The problem you are having is that one of the patterns matches, then gets added to @list1, then gets unmatched by backtracking. But you never remove it from @list1 on backtracking. A simple example of this:

>perl -le"'abc1def2' =~ /(?:([a-z])(?{ print $^N }))+2/" a b c b c c d e f

The solution is to use $^R.

use strict; use warnings; my @vocabulary = qw( a abc abcd abd bc ); my $sentence = 'abdaabc'; my ($pattern) = map qr/$_/, join '|', map quotemeta, sort { length($b) <=> length($a) } # optional @vocabulary; use re 'eval'; local our @list; $sentence =~ / (?{ [] }) ^ (?: ($pattern) (?{ [ @{$^R}, $^N ] }) )+ $ (?{ @list = @{$^R} }) /x or die("No solution\n"); print( join('-', @list), "\n" ); # abd-a-abc

Without the sort, you'd get abd-a-a-bc. If you want all possible solutions:

... use re 'eval'; local our @list; $sentence =~ / (?{ [] }) ^ (?: ($pattern) (?{ [ @{$^R}, $^N ] }) )+ $ (?{ push @list, join('-', @{$^R}) }) (?!) /x; die("No solution\n") if !@list; print("$_\n") for @list;
abd-a-a-bc abd-a-abc

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