Marpa::R2::Scanless::G - Scanless interface grammars
my $grammar = Marpa::R2::Scanless::G->new( { action_object => 'My_Actions', default_action => 'do_first_arg', source => \(<<'END_OF_SOURCE'), :start ::= Script Script ::= Expression+ separator => comma action => do_script comma ~ [,] Expression ::= Number | '(' Expression ')' action => do_parens assoc => group || Expression '**' Expression action => do_pow assoc => right || Expression '*' Expression action => do_multiply | Expression '/' Expression action => do_divide || Expression '+' Expression action => do_add | Expression '-' Expression action => do_subtract Number ~ [\d]+ :discard ~ whitespace whitespace ~ [\s]+ # allow comments :discard ~ <hash comment> <hash comment> ~ <terminated hash comment> | <unterminated final hash comment> <terminated hash comment> ~ '#' <hash comment body> <vertical space char> <unterminated final hash comment> ~ '#' <hash comment body> <hash comment body> ~ <hash comment char>* <vertical space char> ~ [\x{A}\x{B}\x{C}\x{D}\x{2028}\x{2029}] <hash comment char> ~ [^\x{A}\x{B}\x{C}\x{D}\x{2028}\x{2029}] END_OF_SOURCE } );
This page is the reference for the grammar objects of Marpa's Scanless interface.
The new() method is the constructor for Scanless grammars. An example of its use is above. The new() constructor accepts a hash of named arguments. The following named arguments are allowed:
new()
Specifies the action_object named argument that will be used for the G1 grammar. For details, see "action_object" in Marpa::R2::Grammar.
action_object
Specifies the name of a Perl package. The package is used for blessing node values into a Perl class, in conjunction with the bless adverb.
bless
Specifies the default_action named argument that will be used for the G1 grammar. For details, see "default_action" in Marpa::R2::Grammar.
default_action
The value of the source named argument must be a reference to a string which contains a description of the grammar. The string's format is a domain-specific language, described in its own document.
source
The value is a file handle. Trace output and warning messages go to the trace file handle. By default the trace file handle is STDERR.
STDERR
my $show_rules_output = $grammar->show_rules();
The show_rules() method is the equivalent of calling Marpa::R2::Grammar's show_rules() method for both the G0 and G1 grammars. It is useful for showing the rules as they will appear in trace and debugging outputs.
show_rules()
Copyright 2013 Jeffrey Kegler This file is part of Marpa::R2. Marpa::R2 is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. Marpa::R2 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with Marpa::R2. If not, see http://www.gnu.org/licenses/.
To install Marpa::R2, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Marpa::R2
CPAN shell
perl -MCPAN -e shell install Marpa::R2
For more information on module installation, please visit the detailed CPAN module installation guide.