I was playing with some recursive parsing, and made a simple program to parse apart text based on a given list of precedence. I was quite pleased with the result. :)
input#!/usr/bin/perl use warnings; use strict; use Data::Dumper; $Data::Dumper::Terse=1; my $precedence=[qr/&&/,qr/\|\|/,qr/\+/,qr/-/,qr/\//,qr/\*/]; sub parse; while(<>){ my $tree = parse($precedence,$_); print Dumper($tree); } sub parse{ my ($regex,$input)=@_; my ($node,$before,$op,$after); $input=~s/\s//g; for(@$regex){ $input=~m/(.+)($_)(.+)/; if($3){ ($before,$op,$after)=($1,$2,$3); last; } } return $input if !defined($after); $node->{$op}=[parse($regex,$before),parse($regex,$after)]; return $node; }
output5+4*3&&COND||COND2||COND3&&ANOTHER
{ '&&' => [ { '&&' => [ { '+' => [ '5', { '*' => [ '4', '3' ] } ] }, { '||' => [ { '||' => [ 'COND', 'COND2' ] }, 'COND3' ] } ] }, 'ANOTHER' ] }
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Cool Uses for Perl