NAME

Pugs::Compiler::Rule - Compiler for Perl 6 Rules

SYNOPSIS

Un-named rules are objects:

use Pugs::Compiler::Rule;

my $rule = Pugs::Compiler::Rule->compile( '((.).).' );
my $match = $rule->match( 'abc' );

if ($match) {               # true
    print $match;           # "abc"
    print $match->from;     # 0
    print $match->to;       # 3
    print $match->[0];      # "ab"
    print $match->[0][0];   # "a"
}

Named rules are methods in a Grammar:

package MyGrammar;
use Pugs::Compiler::Rule;
use base 'Pugs::Grammar::Base';

Pugs::Compiler::Rule->install( rule => '((.).).' );
my $match = MyGrammar->rule( 'abc' );

Rules may have parameters:

$grammar->install(subrule => $source, { signature => $sig } );

$grammar->install(rule => q{
        <subrule: param1, param2>
});

DESCRIPTION

This module provides an implementation for Perl 6 Rules. It is a front-end to several other modules:

* Front-end Modules

* Pugs::Compiler::Rule compiles Perl 6 Rules to Perl 5.

* Pugs::Compiler::Token compiles Perl 6 Tokens to Perl 5.

* Pugs::Compiler::Regex compiles Perl 6 Regexes to Perl 5.

* Pugs::Compiler::RegexPerl5 wraps Perl 5 Regexes to return a Match object.

* Runtime Classes

* Pugs::Runtime::Rule provides the runtime engine for Rules.

* Pugs::Runtime::Match represents a Match object.

* Pugs::Runtime::Match::Ratchet represents a Match object matched with :ratchet.

* Pugs::Runtime::Grammar represents a Grammar class / object.

* Grammars

* Pugs::Grammar::Rule parses the Rules syntax.

* Pugs::Grammar::Rule::Rule specifies the Rules syntax with Rules.

* Pugs::Grammar::Base is the base Grammar: <ws>, <space>.

* Code Emitters

* Pugs::Emitter::Rule::Perl5 converts parsed Rules to Perl 5 code.

* Pugs::Emitter::Rule::Perl5::Ratchet converts parsed :ratchet Rules to Perl 5 code.

Implemented Features

 <ws> 
 #comment\n 
 . 
 ? * + *? +? ??
 literal
 [] 
 ()     
 |

 <'literal'>
 <subrule>
 <namespace::subrule>
 <$var>      
 <?subrule>
 <!subrule>
 <before ...>
 <after ...>         -- implemented in :ratchet mode only
 <subrule('param')>  -- constant parameters only

 %hash

 <@var>             -- special-cased for array-of-rule (but not Rule|Str)
 \char              -- not all chars implemented
 {code}             -- non-capturing closure
                    -- perl5 syntax inside closure
                    -- $/ doesn't work yet
 { return code }    -- capturing closure
                    -- perl5 syntax inside closure
                    -- $/ works
 $var := (capture)  -- capture aliasing
 $<> $/<>           -- special variables can't be used inside a match yet
 $/ 
 $<0> $<1>
 $0 $1
 \n \N
 $^a $^b            -- positional parameters (must start with $^a)
 ^ $
 :

Unimplemented or untested features

$variable 
@variable
$/<0> $/<1>
$/0 $/1
<"literal">
^^ $$
<unicode-class> <+unicode-class> <+unicode-class+unicode-class>
<&var> 
<%var>
**{n..m}
:: :::   (commit)
$var := [non-capture]
$var := <rule>
<(closure-assertion)> <{code-returns-rule}>
<<character-class>> <[character-class]>
:flag :flag() :flag[]
\x0a \0123 ...
&    
$1      - lvalue match variables
$/ $()  - global match variables 

METHODS

compile (Str $rule_source, \%options)

Class method. Returns a compiled rule object, or throws an exception on invalid rule syntax.

options:

grammar => $class

Specify which namespace (Grammar) the rule belongs to.

* ratchet => 1

Disable backtracking. Match faster. Defaults to 1 in Rules and Tokens.

* pos => $pos

Specify a string position to match. Starts in zero. Defaults to undef.

* sigspace => 1

Whitespace is significant. Defaults to 1 in Rules.

* Perl5 => 1

Use Perl 5 grammar and semantics for Regex.

match (Str $match_against)

Instance method. Returns a Pugs::Runtime::Match object (or Pugs::Runtime::Match::Ratchet).

install (Str $name, Str $rule_source, \%options)

Install a rule into the method $name. If $name is fully qualified then it will be installed into that path e.g MyGrammar::rulename, otherwise it will install it into the current package.

perl5

Instance method. Returns a string that can be eval'ed into a rule/token/regex object.

CAVEATS

This is an experimental development version. The API is still in flux.

The set of implemented features depends on the ratchet switch.

AUTHORS

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

Please join us on irc.freenode.net #perl6 if you'd like to participate.

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

cpanm Pugs::Compiler::Rule

perl -MCPAN -e shell
install Pugs::Compiler::Rule