Re: Compare two regex patterns

from the looks of it, a good solution may be to use Regexp::Optimizer on both values. Then see if they are equal after

Comment on Re: Compare two regex patterns

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Re^2: Compare two regex patterns by ikegami (Patriarch) on Mar 06, 2008 at 15:38 UTC
That doesn't work for two reasons. 1. Regexp::Optimizer is a no-op if no alternation is used. 2. Even if Regexp::Optimizer normalized regexps, the normalized regexps still wouldn't be equal since the two regexps are not equivalent. `use Regexp::Optimizer qw( ); my $o = Regexp::Optimizer->new(); print $o->optimize(qr/123/), "\n"; # (?-xism:123) print $o->optimize(qr/1233/), "\n"; # (?-xism:1233) print $o->optimize(qr/123+/), "\n"; # (?-xism:123+)` [download] The OP didn't ask for a method to check if two regexp are equivalent, but for a method to check if a regexp will match at least everything a second regexp matches. Update: Added code. Changed formatting.	[reply] [d/l]

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Re^2: Compare two regex patterns
by ikegami (Patriarch) on Mar 06, 2008 at 15:38 UTC

That doesn't work for two reasons.

1. Regexp::Optimizer is a no-op if no alternation is used.

2. Even if Regexp::Optimizer normalized regexps, the normalized regexps still wouldn't be equal since the two regexps are not equivalent.

use Regexp::Optimizer qw( );
my $o = Regexp::Optimizer->new();
print $o->optimize(qr/123*/),  "\n";  # (?-xism:123*)
print $o->optimize(qr/1233*/), "\n";  # (?-xism:1233*)
print $o->optimize(qr/123+/),  "\n";  # (?-xism:123+)
[download]

The OP didn't ask for a method to check if two regexp are equivalent, but for a method to check if a regexp will match at least everything a second regexp matches.

Update: Added code. Changed formatting.

[reply]
[d/l]

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