Language::Tea::Traverse - Iterates into the Tea Op Tree

Language-Tea documentation Contained in the Language-Tea distribution.

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NAME

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Language::Tea::Traverse - Iterates into the Tea Op Tree

SYNOPSIS

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  use Language::Tree::Traverse;
  my $node = traverse_postfix($root, sub { }, []);
  my $node = traverse_prefix($root, sub { }, []);

DESCRIPTION

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This module iterates through the tree in two different ways

traverse_postfix($node, $visitor = sub { my ($node, \@children, @_) = @_ });

Bottom-up traversal. The visitor will receive both the current node and the result of the processing for each sub-node. As any other arguments passed to traverse_postfix.

traverse_prefix($node, $visitor = sub { my ($node, \@parents, @_) = @_ });

Top-Down traversal. The visitor will receive both the current node and the result of the processing for each upper level in the three (from the closest to the farest). It will also receive any other argument passed to traverse_prefix.

Language-Tea documentation Contained in the Language-Tea distribution. 
package Language::Tea::Traverse;

use strict;
use warnings;
use UNIVERSAL qw(isa can);
use Scalar::Util qw(blessed);

sub visit_prefix {
    my ( $node, $visitor, $parent );
    my $path;
    if ( ref( $_[0] ) eq 'PATH' ) {
        $node = $_[0];
        $path = $node->[0];
    }
    else {
        ( $node, $visitor, $parent ) = ( shift, shift, shift );
    }

    if ( ref($node) eq 'ARRAY' ) {

        my $h = [];
        for my $key ( 0 .. $#$node ) {
            my $res = visit_prefix( $node->[$key], $visitor, $parent, @_ );
            if ($res) {
                push @$h, $res;
            }
            else {
                push @$h, $node->[$key];
            }
        }
        return $h;
    }
    elsif ( ref $node eq 'HASH' || blessed $node) {

        my $visited = $visitor->( $node, $parent, @_ );
        return $visited if defined $visited;

        my $h = {};
        for my $key ( sort keys %$node ) {
            my $res;
            if ( $key ne '__node_parent__' ) {
                $res =
                  visit_prefix( $node->{$key}, $visitor,
                    ref $node eq 'HASH' ? $parent : $node, @_ );
            }
            if ($res) {
                $h->{$key} = $res;
            }
            else {
                $h->{$key} = $node->{$key};
            }
        }
        bless $h, ref($node)
          unless ref($node) eq 'HASH';

        return $h;
    }
    else {
        return $node;
    }
}

sub visit_postfix {
    my ( $node, $visitor, $parent ) = ( shift, shift, shift );
    if ( ref($node) eq 'ARRAY' ) {
        my $h = [];
        for my $key ( 0 .. $#$node ) {
            my $res = visit_postfix( $node->[$key], $visitor, $parent, @_ );
            if ($res) {
                push @$h, $res;
            }
            else {
                push @$h, $node->[$key];
            }
        }
        return $h;
    }
    elsif ( ref $node eq 'HASH' || blessed $node) {

        #print ref($node),"\n";
        my $h = {};
        for my $key ( sort keys %$node ) {
            my $res;
            if ( $key ne '__node_parent__' ) {
                $res =
                  visit_postfix( $node->{$key}, $visitor,
                    ref $node eq 'HASH' ? $parent : $node, @_ );
            }
            if ($res) {
                $h->{$key} = $res;
            }
            else {
                $h->{$key} = $node->{$key};
            }
        }
        bless $h, ref($node)
          unless ref($node) eq 'HASH';

        my $res = $visitor->( $h, $parent, @_ );
        return $res if $res;

        return $h;
    }
    else {
        return $node;
    }
}

1;

__END__