NAME

Pugs::Compiler::Regex - Compiler for Perl 6 Regex

SYNOPSIS

use Pugs::Compiler::Regex;
use Pugs::Runtime::Match;

$regex = Pugs::Compiler::Regex->compile('a*b');
$match = $regex->match('aaab');
print $match->(), "\n";
print $match->from, "\n";
print $match->to, "\n";

package MyGrammar;
$regex = Pugs::Compiler::Regex->compile(
    'a*', { ratchet => 1, continue => 1, sigspace => 1 }
);
*my_match = $regex->code();
$match = MyGrammar->my_match('aaaa');
print "$match\n";

package MyGrammar2;
$regex = Pugs::Compiler::Regex->install(
    my_match => 'a*',
    { ratchet => 1, continue => 1, sigspace => 1 }
);
$match = MyGrammar->my_match('aaaa');
print "$match\n";

DESCRIPTION

This class provides an implementation for Perl 6 regexes. It serves as a base class for Pugs::Compiler::Rule and Pugs::Compiler::Token.

METHODS

$regex = Pugs::Compiler::Regex->compile($str, $params);

This method acts like a constructor, which returns a Pugs::Compiler::Regex object from the p6 regex specified in $str, or throws an exception on invalid rule syntax.

$params is an optional argument which specifies the following p6 regex modifiers:

grammar => 'Pugs::Grammar::Base'

Specify which namespace (Grammar) the rule belongs to. if grammar is not specified, then "Pugs::Grammar::Base" will be assumed.

continue => 0

c => 0

These modifiers cause the pattern to continue scanning from the string's current pos:

Note that in Perl 6 form

m:c/pattern/

is roughlh equivalent to

m:p/ .*? pattern /

Here is an example:

package Foo;
Pugs::Compiler::Regex->install(
    word => '\w+',
    { ratchet => 1, continue => 1 }
);
$s = 'hello world';
$match = Foo->word($s); # got 'hello'
$match = Foo->word($s); # got 'world'

XXX Note that continue or c currently are not supported in non-ratchet mode.

ratchet => 0

Disable backtracking. Much faster. Defaults to 0. (Pugs::Compiler::Rule and Pugs::Compiler::Token have the default value of 1).

pos => undef

p => undef

Specify a string position to match. Starts from zero. Defaults to undef, which matches anywhere in the string.

sigspace => 0

Whitespace is significant. Defaults to 0 for Pugs::Compiler::Regex while 1 for Pugs::Compiler::Rule.

ignorecase => 0

Ignore character case. Defaults to 0 for Pugs::Compiler::Regex.

$regex->perl5()

$regex->perl()

Return a string holding the Perl 5 code for reconstructing the current Pugs::Compiler::Regex object.

We are trying to make the perl5 method does something like serializing a Pugs::Compiler::Regex instance.

If you want the raw Perl 5 code generated by the various emitters, use $regex->{perl5} directly.

$regex->match($str, $grammar, $params)

Performs matching action on $str. Note that it's a thin wrapper around the p5 code compiled from the p6 regex with run-time modifier handling via the $params argument.

Here is an example:

$regex = Pugs::Compiler::regex->compile('a*\w');
my $match = $regex->match('aaa');
print "Capture: $match";
print "From: ", $match->from;
print "To: ", $match->to;

$regex->code()

Returns a closure (or an anonymous sub) which does the actual matching task. For example:

$regex = Pugs::Compiler::Regex->compile('a|b', { ratchet => 1 });
my $sub = $regex->code();
my $match = $sub->('MyGrammar', 'aaa');

Or inserts the sub into the current package:

package Foo;
$regex = Pugs::Compiler::Regex->compile('a*');
*match = $regex->code();
my $match = __PACKAGE__->match('aaa');

Technically it's a thin wrapper around the match method.

$regex->install($name, @args_for_compile)

Installs the subroutine returned from the code method as a named subroutine using the name specified by $name;

If $name is fully qualified, then the corresponding package is used, otherwise the current package is assumed.

@args_for_compile are those arguments fed into the compile method.

It will croak if there's already a sub with the same name exists. If that's not what you want, use the reinstall method instead.

Here are some examples:

package Bar;
Pugs::Compiler::Regex->install(match => 'a*', {ratchet => 1});
$match = Bar->match('aaa');

# The following line dies with the message
# "Can't install regex 'match' as 'Bar::match' which already
# exists":
Pugs::Compiler::Regex->install(match => 'b*');

$regex->reinstall($name, @args_for_compile)

Like the install method but it can replaces the named sub if it already exists:

package Bar;
Pugs::Compiler::Regex->install('match', 'a*', {ratchet => 1});
Pugs::Compiler::Regex->reinstall('match', 'b*');
};
$match = Bar->match('bbb'); # matched here

PACKAGE VARIABLES

$Pugs::Compiler::Regex::NoCache

By default, the compile method will cache the compiled form (p5 source) of the p6 regex. The NoCache variable prevents any caching.

AUTHORS

The Pugs Team <perl6-compiler@perl.org>.

SEE ALSO

The Perl 6 Rules Spec: http://dev.perl.org/perl6/doc/design/syn/S05.html

COPYRIGHT

Copyright 2006 by Flavio Soibelmann Glock and others.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See http://www.perl.com/perl/misc/Artistic.html