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Generate a single "or regex" from given strings

by Anonymous Monk
on Sep 27, 2013 at 14:51 UTC ( #1055990=CUFP: print w/ replies, xml ) Need Help??

I got tired of remaking regex (of email addresses) for use by procmail and mutt by hand. Then I wrote the following. The worst case is every string is simply joined, which is still better than manual operation. Ideally one of three modules -- Regexp::(Assemble|Optimizer|Trie) -- will be used to generate the regex when available.

Mind that ...

  • /i flag is used; feel free to make it optional yourself;
  • duplicates in input are not considered;
  • end-spaces are removed.
#!perl use strict; use warnings; our $VERSION = '0.07'; # or-re.pl - Given a list of strings, prints a OR'd regex; prints tes +t results # for the input. # # End-spaces & duplicate strings are removed before generating the re +gex. scalar @ARGV or die qq[Give strings to make one "or" regex.\n]; my @list = prepare( @ARGV ); my $re = build_re( @list ); printf "Regex...\n %s\n\n" , $re; re_test( $re , @list ); exit; sub re_test { my ( $re , @list ) = @_; ref $re or $re = qr/$re/; print "Test ...\n"; for my $it ( @list ) { printf " %s %14s\n" , $it , ( $it =~ $re ? 'matches' : 'does NOT match' ) ; } return; } sub prepare { scalar @_ or return; my %seen; return map { s/^\s+//; s/\s+$//; !$seen{ $_ }++ ? $_ : () } @_; } sub build_re { scalar @_ or return ''; my @arg = @_; my %mod_map = ( 'Regexp::Assemble' => \&via_assemble , 'Regexp::Optimizer' => \&via_optimizer , 'Regexp::Trie' => \&via_trie , 'mine' => sub { return decorate( simpleton( @_ ) ) +} ); my @order = ( 'Regexp::Assemble' , 'Regexp::Optimizer' , 'Regexp::Trie' ); my $maker = 'mine'; for my $mod ( @order ) { _load_module( $mod ) or next; $maker = $mod; last; } return $mod_map{ $maker }->( @arg ) } sub decorate { return qq/\\b(?i:$_[0])\\b/ ; } sub simpleton { return join '|' , map { quotemeta( $_ ) } sort { length $b <=> length $a || lc $a cmp lc $b } @_ ; } sub via_assemble { my $maker = Regexp::Assemble->new( 'chomp' => 1 , 'reduce' => 1 , 'modifiers' => 'i' , 'anchor_word' => 1 ); $maker->add( map quotemeta( $_ ) , @_ ); # R:A::as_string() method eschews flags given. This preserves it at +the cost # of extraneous syntax elsewhere. return $maker->re() . ''; } sub via_optimizer { my $re = simpleton( @_ ); my $maker = Regexp::Optimizer->new(); return $maker->as_string( qr/\b(?:$re)\b/i ); } sub via_trie { my $maker = Regexp::Trie->new(); # Cannot add as list, unlike R::Assemble. $maker->add( $_ ) for @_; return $maker->regexp() . ''; } sub _load_module { my ( $mod ) = @_; local $@; eval qq/ require $mod; 1; /; $@ and do { warn "Could not load $mod: $@\n"; return; }; warn "# Using $mod ...\n"; return 1; }

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Re: Generate a single "or regex" from given strings
by LanX (Canon) on Sep 27, 2013 at 14:57 UTC
    (maybe TL;DR but as a side remark)

    Trie optimization is a builtin since Perl 5.10, maybe you should test that too.

    Cheers Rolf

    ( addicted to the Perl Programming Language)

Re: Generate a single "or regex" from given strings
by toolic (Chancellor) on Sep 27, 2013 at 15:37 UTC
    To reduce the excessive verbosity when the modules can't be loaded, change:
    $@ and do { warn "Could not load $mod: $@\n"; return; };

    to:

    $@ and do { warn "Could not load $mod\n"; return; };

      Yes, that and other things may be optionally turned off|on if anyone else cares to implement.

Re: Generate a single "or regex" from given strings
by Anonymous Monk on Sep 27, 2013 at 22:13 UTC

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