Doubly-linked list/Traversal: Difference between revisions

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=={{header|Oforth}}==

Complete definition is here : [[../Definition#Oforth]]

Defining #forEachNext and #forEachPrev allow to traverse this double linked list using #forEach: and #revEach: syntax

<lang oforth>DList method: forEachNext

{

dup ifNull: [ drop @head ifNull: [ false ] else: [ @head @head true] return ]

next dup ifNull: [ drop false ] else: [ dup true ]

}

DList method: forEachPrev

{

dup ifNull: [ drop @tail ifNull: [ false ] else: [ @tail @tail true] return ]

prev dup ifNull: [ drop false ] else: [ dup true ]

}

: test

{

| dl n |

DList new ->dl

dl insertFront("A")

dl insertBack("B")

dl head insertAfter(DNode new("C", null , null))

"Traversal (beginning to end) : " println

dl forEach: n [ n . ]

"\nTraversal (end to beginning) : " println

dl revEach: n [ n . ]

}</lang>

{{out}}

<pre>

>test

Traversal (beginning to end) :

A C B

Traversal (end to beginning) :

B C A ok