Name

Marpa::R2::Scanless::R - Scanless interface recognizers

This document is UNDER CONSTRUCTION

Synopsis

my $recce = Marpa::R2::Scanless::R->new( { grammar => $grammar } );
my $self = bless { grammar => $grammar }, 'My_Actions';
$self->{recce} = $recce;
local $My_Actions::SELF = $self;

my $event_count;
if ( not defined eval { $event_count = $recce->read($p_input_string); 1 }
    )
{
    ## Add last expression found, and rethrow
    my $eval_error = $EVAL_ERROR;
    chomp $eval_error;
    die $self->show_last_expression(), "\n", $eval_error, "\n";
} ## end if ( not defined eval { $event_count = $recce->read...})

if ( not defined $event_count ) {
    die $self->show_last_expression(), "\n", $recce->error();
}
my $value_ref = $recce->value();
if ( not defined $value_ref ) {
    die $self->show_last_expression(), "\n",
        "No parse was found, after reading the entire input\n";
}

package My_Actions;

our $SELF;
sub new { return $SELF }

sub do_parens    { shift; return $_[1] }
sub do_add       { shift; return $_[0] + $_[2] }
sub do_subtract  { shift; return $_[0] - $_[2] }
sub do_multiply  { shift; return $_[0] * $_[2] }
sub do_divide    { shift; return $_[0] / $_[2] }
sub do_pow       { shift; return $_[0]**$_[2] }
sub do_first_arg { shift; return shift; }
sub do_script    { shift; return join q{ }, @_ }

sub show_last_expression {
    my ($self) = @_;
    my $recce = $self->{recce};
    my ( $start, $end ) = $recce->last_completed_range('Expression');
    return 'No expression was successfully parsed' if not defined $start;
    my $last_expression = $recce->range_to_string( $start, $end );
    return "Last expression successfully parsed was: $last_expression";
} ## end sub show_last_expression

About this document

This page is the reference document for the recognizer objects of Marpa's Scanless interface.

Methods

error()

last_completed_range()

new()

range_to_string()

read()

show_progress()

trace()

value()

Copyright and License

Copyright 2012 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/.