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Pugs::Compiler::Regex.3pm

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>