txt: ## dist_zef-raku-community-modules-Grammar-BNF.md
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  # NAME
  
  Grammar::BNF - Parse (A)BNF grammars and generate Raku grammars from them
  
  # SYNOPSIS
  
  ```
  use Grammar::BNF;
  my $g = Grammar::BNF.generate(Q:to<END>);
    <foo2> ::= <foo> <foo>
    <foo> ::= "bar"
    END
  
  ```
  
  # DESCRIPTION
  
  This distribution contains modules for creating Raku Grammar objects using BNF flavored grammar definition syntax. Currently BNF and ABNF are supported.
  
  In addition, the distribution contains Slang modules which allow use of the grammar definition syntax inline in Raku code. These modules may relax their respective syntax slightly to allow for smoother language integration.
  
  # IDIOMS
  
  This simple example shows how to turn a simple two-line grammar definition in BNF syntax into a grammar named `MyGrammar`, and then uses the resulting grammar to parse the string 'barbar';
  
  ```
  use Grammar::BNF;
  my $g = Grammar::BNF.generate(Q:to<END>);
    <foo2> ::= <foo> <foo>
    <foo> ::= "bar"
    END
                                );
  $g.parse('barbar').say; # ｢barbar｣
                          #  foo2 => ｢barbar｣
                          #   foo => ｢bar｣
                          #   foo => ｢bar｣
  
  ```
  
  Alternatively, you may use a slang to define grammars inline:
  
  ```
  use Slang::BNF;
  bnf-grammar MyGrammar {
      <foo2> ::= <foo> <foo>
      <foo> ::= "bar"
  }; # currently you need this semicolon
  MyGrammar.parse('barbar').say; # same as above
  
  ```
  
  In either case, the first rule appearing in the grammar definition will be aliased to 'TOP', and will be the default rule applied by `.parse`. This is in most respects a true Raku, so subrules may be invoked:
  
  ```
  MyGrammar.parse('bar',:rule<foo>).say; # ｢bar｣
  
  ```
  
  ...and the Grammar may be subclassed to add or replace rules with Perl 6 rules:
  
  ```
  grammar MyOtherGrammar is MyGrammar {
      token foo { B <ar> }
      token ar  { ar }
  }
  MyOtherGrammar.parse('BarBar').say; # ｢BarBar｣
                                      #  foo2 => ｢BarBar｣
                                      #   foo => ｢Bar｣
                                      #    ar => ｢ar｣
                                      #   foo => ｢Bar｣
                                      #    ar => ｢ar｣
  
  ```
  
  Currently you have to subclass with a Raku grammar for actions classes to be provided, but hopefully that limitation will be overcome:
  
  ```
  class MyActions { method foo ($match) { "OHAI".say } }
  MyOtherGrammar.parse('BarBar', :actions(MyActions)); # says OHAI twice
  
  ```
  
  # AUTHOR
  
  Tadeusz Sośnierz
  
  # COPYRIGHT AND LICENSE
  
  Copyright 2010 - 2017 Tadeusz Sośnierz
  
  Copyright 2024 Raku Community
  
  This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.
  