Created
December 19, 2020 17:22
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#!/usr/bin/env perl | |
use v5.18; | |
use strict; | |
our %rules; | |
sub compile_rule { | |
state %compiled; | |
my $idx = shift; | |
return $compiled{$idx} if exists $compiled{$idx}; | |
my $rule = $rules{$idx}; | |
if ($rule =~ /^\"(.)\"$/) { | |
return $1; | |
} | |
my @parts = split /\s*\|\s*/, $rule; | |
my @compiled_parts; | |
foreach my $part (@parts) { | |
my @deps = split /\s+/, $part; | |
push @compiled_parts, (join '', map { compile_rule($_) } @deps); | |
} | |
my $res = join '|', @compiled_parts; | |
$res = "(?:$res)"; | |
$compiled{$idx} = $res; | |
$res | |
} | |
while (my $rule = <>) { | |
chomp $rule; | |
last unless $rule; | |
my ($idx, $body) = split /: /, $rule; | |
$rules{$idx} = $body; | |
} | |
my $reg = compile_rule 0; | |
say STDERR "Generated regex (@{[length $reg]} characters)"; | |
$reg = qr/^$reg$/; | |
my $count; | |
while (<>) { | |
$count++ if /$reg/; | |
} | |
say $count; |
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