(generate-codes) ( huff-tree -- code-dict )

Vocabulary

compression.huffman.private

Inputs

huff-tree

an object

Outputs

code-dict

an object

Definition

USING: accessors assocs bit-arrays combinators hashtables kernel
sequences ;

IN: compression.huffman.private

: (generate-codes) ( huff-tree -- code-dict )
    {
        {
            [ dup leaf? ]
            [ code>> ?{ } swap H{ } clone ?set-at ]
        }
        {
            [ dup left>> not ]
            [
                right>> (generate-codes)
                [ ?{ t } prepend ] assoc-map
            ]
        }
        {
            [ dup right>> not ]
            [
                left>> (generate-codes)
                [ ?{ f } prepend ] assoc-map
            ]
        }
        [
            [
                left>> (generate-codes)
                [ ?{ f } prepend ] assoc-map
            ] [
                right>> (generate-codes)
                [ ?{ t } prepend ] assoc-map
            ] bi assoc-union!
        ]
    } cond ;