Pegex::Regex(3) User Contributed Perl Documentation Pegex::Regex(3)

Pegex::Regex - Use Pegex Like a Regex

{
    # Turn on Pegex regular expressions in lexical scope.
    use Pegex::Regex;
    my $grammar = qr{$grammar_text}x;
    $text =~ $grammar;
    my $result = \%/;
    # Turn off Pegex in this scope.
    no Pegex::Regex;
}

This is a trivial sugar module that lets you use Pegex parser grammars like regular expressions, if you're into that kind of thing.

This is basically a clone of Damian Conway's Regexp::Grammars module API. You put a grammar into a "qr{...}x" and apply it the input string you want to parse. If the parse is successful, you get a data structure of the content in "%/".

IMHO, building a recursive descent parser entirely inside of a regular expression, is not the clearest way to code. But, of course, TMTOWTDI. :)

This module is just for experimental fun. See Pegex for the right way to use the Pegex parsing framework.

Here's a Pegex::Regex code snippet:

use Pegex::Regex;
$text =~ qr{... Pegex grammar text ...};
$data = \%/;

And the equivalent Pegex code:

use Pegex;
my $data = pegex('... Pegex grammar text ...')->parse($text);

This gateway drug, er, module, technically should not even work.

It turns your "grammar inside a regexp" into a Pegex::Grammar using qr{} overloading, and then turns your regexp itself into a shim that calls the parse method for you. This is highly magical and technically makes a reentrant call to the regex engine, which is not supported yet. Use at your own risk.

Better yet, do yourself a favor and learn how to use the Pegex toolset without this ::Regex sugar. ":-)"

  • Pegex
  • Regexp::Grammars

Ingy döt Net <ingy@cpan.org>

Copyright 2010-2020. Ingy döt Net.

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2024-09-01 perl v5.40.0