# Module of TWiki Enterprise Collaboration Platform, http://TWiki.org/
#
# Copyright (C) 2005-2013 Peter Thoeny, peter[at]thoeny.org
# and TWiki Contributors. All Rights Reserved. TWiki Contributors
# are listed in the AUTHORS file in the root of this distribution.
# NOTE: Please extend that file, not this notice.
#
# Additional copyrights apply to some or all of the code in this
# file as follows:
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version. For
# more details read LICENSE in the root of this distribution.
#
# This program 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.
#
# As per the GPL, removal of this notice is prohibited.
#
# Author: Crawford Currie http://c-dot.co.uk

=pod

---+ package TWiki::Infix::Node

Base class for node types generated by Infix::Parser. You don't *have* to use
it, but it may be useful.

=cut

package TWiki::Infix::Node;

use strict;

# 1 for debug
sub MONITOR_EVAL   { 0 };

# Leaf token types
use vars qw ($NAME $STRING $NUMBER);
$NAME = 1;
$NUMBER = 2;
$STRING = 3;

=pod

---++ ClassMethod newNode( $o, @p ) -> \$if

Construct a new parse node (contract with Infix::Parser)

=cut

sub newNode {
    my $class = shift;
    my $op = shift;
    my $this = bless( {}, $class );
    @{$this->{params}} = @_;
    $this->{op} = $op;
    return $this;
}

=pod

---++ ClassMethod newLeaf( $val, $type ) -> \$if

Construct a new terminal node (contract with Infix::Parser)

=cut

sub newLeaf {
    my( $class, $val, $type ) = @_;
    return newNode( $class, $type, $val );
}

=pod

---++ ObjectMethod evaluate(...) -> $result

Execute the parse node. The parameter array is passed on, by reference,
to the evaluation functions.

=cut

sub evaluate {
    my( $this, $clientData ) = @_;

    my $result;
    if (!ref( $this->{op})) {
        $result = $this->{params}[0];
        if (MONITOR_EVAL) {
            print STDERR "LEAF: ",(defined($result)?$result:'undef'),"\n";
        }
    } else {
        my $fn = $this->{op}->{evaluate};
        $result = &$fn( $clientData, @{$this->{params}} );
        if (MONITOR_EVAL) {
            print STDERR "NODE: ",$this->stringify()," -> ",
              (defined($result)?$result:'undef'),"\n";
        }
    }
    return $result;
}

sub stringify {
    my $this = shift;

    unless( ref( $this->{op} )) {
        if( $this->{op} == $TWiki::Infix::Node::STRING ) {
            return "'$this->{params}[0]'";
        } else {
            return $this->{params}[0];
        }
    }

    return $this->{op}->{name}.'{'.
      join(',', map { $_->stringify() } @{$this->{params}}).'}';
}

1;
