Forest::Tree::Builder - An abstract role for bottom up tree reader


Forest documentation Contained in the Forest distribution.

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NAME

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Forest::Tree::Builder - An abstract role for bottom up tree reader

SYNOPSIS

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    package MyBuilder;
    use Moose;

    with qw(Forest::Tree::Builder);

    # implement required builder:

    sub _build_subtrees {
        return [
            $self->create_new_subtree( ... ), # probably a recursive process
        ];
    }




    my $builder = MyBuilder->new(
        tree_class => ...,
        ...
    );

    my $tree = $builder->tree;

DESCRIPTION

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Forest::Tree::Builder replaces Forest::Tree::Loader and Forest::Tree::Reader with a bottom up construction approach, which is also suitable for constructing Forest::Tree::Pure derived trees without excessive cloning.

It provides a declarative API instead of an imperative one, where tree is lazily constructed on the first use, instead of being constructed immediately and "filled in" by the load method.

METHODS

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create_new_subtree

Implemented by Forest::Tree::Constructor

_build_tree

Constructs a root node by using the top level subtrees list as the children.

_build_subtrees

Build the subtrees.

Abstract method that should return an array ref of Forest::Tree::Pure derived objects.

SEE ALSO

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Forest::Tree::Builder::SimpleTextFile

BUGS

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All complex software has bugs lurking in it, and this module is no exception. If you find a bug please either email me, or add the bug to cpan-RT.

AUTHOR

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Yuval Kogman

COPYRIGHT AND LICENSE

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Forest documentation Contained in the Forest distribution.

package Forest::Tree::Builder;
use Moose::Role;

our $VERSION   = '0.09';
our $AUTHORITY = 'cpan:STEVAN';

with qw(Forest::Tree::Constructor);

has 'tree' => (
    is         => 'ro',
    writer     => "_tree",
    isa        => 'Forest::Tree::Pure',
    lazy_build => 1,
);

has tree_class => (
    isa => "ClassName",
    is  => "ro",
    reader => "_tree_class",
    default => "Forest::Tree",
);

# horrible horrible kludge to satisfy 'requires' without forcing 'sub
# tree_class {}' in every single class. God i hate roles and attributes
sub tree_class { shift->_tree_class(@_) }

sub _build_tree {
    my $self = shift;

    $self->create_new_subtree(
        children => $self->subtrees,
    );
}

has subtrees => (
    isa => "ArrayRef[Forest::Tree::Pure]",
    is  => "ro",
    lazy_build => 1,
);

requires "_build_subtrees";

# ex: set sw=4 et:

no Moose::Role; 1;

__END__