Dogcows Code - chaz/p5-Acme-Test-LogicalEquivalence/blob - bin/test-logical-equivalence

   1 #!perl
   2 # ABSTRACT: Test if expressions are logically equivalent
   3 # PODNAME: test-logical-equivalence
   4
   5 =head1 SYNOPSIS
   6
   7     # be sure to escape $ and other special characters from your shell
   8     test-logical-equivalence '$a && $b' '$b && $a'
   9
  10 =head1 SEE ALSO
  11
  12 =for :list
  13 * L<Acme::Test::LogicalEquivalence>
  14
  15 =cut
  16
  17 use 5.008;
  18 use warnings FATAL => 'all';
  19 use strict;
  20
  21 use Test::More;
  22 use Acme::Test::LogicalEquivalence qw(is_logically_equivalent);
  23
  24 sub usage {
  25     print <<END;
  26 $0 EXPR1 EXPR2
  27 Test if two simple expressions are logically equivalent.
  28
  29 Exactly two expressions must be given.
  30
  31 Example: $0 '\$a || \$b' '\$b || \$a'
  32 Remember that you may need to escape special characters like "\$" from your shell.
  33 END
  34     exit 1;
  35 }
  36
  37 sub find_num_vars {
  38     my $expr = shift;
  39
  40     my $highest = -1;
  41
  42     # check for scalars that look like $a or $b
  43     for my $varname ($expr =~ /\$([a-z])/g) {
  44         my $num = ord($varname) - 97;
  45         $highest = $num if $highest < $num;
  46     }
  47
  48     # check for scalars that index $_
  49     for my $varname ($expr =~ /\$_\[(\d+)\]/g) {
  50         my $num = $varname;
  51         $highest = $num if $highest < $num;
  52     }
  53
  54     return $highest + 1;
  55 }
  56
  57 my $expr1 = shift or usage;
  58 my $expr2 = shift or usage;
  59
  60 my $numvars1 = find_num_vars($expr1);
  61 my $numvars2 = find_num_vars($expr2);
  62 my $num = $numvars1 > $numvars2 ? $numvars1 : $numvars2;
  63
  64 if ($num < 1) {
  65     print STDERR 'No variables detected. Variables should be one or more of $a, $b, ..., $z', "\n";
  66     exit 2;
  67 }
  68
  69 # convert $a-style vars to $_[0]-style to support more than just $a and $b
  70 $expr1 =~ s/\$([a-z])/'$_['.(ord($1) - 97).']'/ge;
  71 $expr2 =~ s/\$([a-z])/'$_['.(ord($1) - 97).']'/ge;
  72
  73 my $sub1 = eval "sub { $expr1 }" or die "Expression 1: $@\n";   ## no critic (ProhibitStringyEval)
  74 my $sub2 = eval "sub { $expr2 }" or die "Expression 2: $@\n";   ## no critic (ProhibitStringyEval)
  75
  76 plan tests => (2 ** $num);
  77 note "Testing for logical equivalence of two expressions with $num variable(s)...";
  78
  79 my $equivalence = is_logically_equivalent($num, $sub1, $sub2);
  80 note $equivalence ? 'Logical equivalence proved!' : 'Bummer...';
  81