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

Rules may have parameters:

            

              
              
*subrule = $grammar->compile( $source, { signature => $sig } )->code;
*rule = $grammar->compile( '
        <subrule: param1, param2>
    ' )->code;
            
          

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).

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