support of parsing from a non TOP rule

[Stéphane Payrard]

Hi,

the attached patch modifying  HLLCompiler.pir supports parsing from an
arbitrary rule in a grammar, using the $:rule parameter

Example :

 grammar A { token a { a } }; say A.parse('a', :rule<a>).perl

This is nice for testing part of a grammar.
This patch is the result of the following conversation with TimToady :


http://irclog.perlgeek.de/perl6/2010-06-01#i_2391972

23:34   cognominal      rakudo:   'grammar A {  token a { a } };  say 'a' ~~
/<A::a>/ # what is the proper way to directly use a rule from a
grammar
23:34   p6eval  rakudo 18d996: OUTPUT«===SORRY!===␤Confused at line 11,
near "'grammar A"␤»
23:37           Schwern joined #perl6
23:43   TimToady        rakudo: grammar A { token a { a } }; say A.parse('a',
:rule<a>).perl
23:43   p6eval  rakudo 18d996: OUTPUT«Match.new(␤ # WARNING: this is not
working perl code␤ # and for debugging purposes only␤ ast  => Any,␤
Str  => "a",␤ from => 0,␤ orig => "a",␤ to   => 1,␤)␤»
23:43   TimToady        something like that

-- 
cognominal stef

parrot-parse_with_rule.2010-06-02.patch
Description: Binary data