double_linked_list.tea

#!/opt/TeaAgeSolutions/TeaScript/bin/TeaScript
/*
 * SPDX-FileCopyrightText:  Copyright (C) 2023 Florian Thake, <contact |at| tea-age.solutions>.
 * SPDX-License-Identifier: MIT
 * see included file MIT_LICENSE.txt
 */
 
// This is a demo script for showing a double linked list with the help of named tuples.

// NOTE: If you need a list, using an index based tuple together with the following helper functions is a common alternative:
//       _tuple_append, _tuple_insert, _tuple_remove, _tuple_swap + the ordinary other tuple functions.


// factory function for a new node with payload data
func create_node( data )
{
    def node      := _tuple_create()   // empty tuple
    def node.prev := _tuple_create()   // empty tuple
    def node.next := _tuple_create()   // empty tuple
    def node.data := data
    node
}


// insert a new node with given data right after the given node.
func insert( node @=, data )
{
    def new := create_node( data )

    if( node.next ) { // checks for not empty tuple
        new.next @= node.next
        node.next.prev @= new
    }
    node.next @= new
    new.prev  @= node

    void
}


// create the head of the list

def head := create_node( 1 )

// insert some data....
insert( head, 4 )
insert( head, 3 )
insert( head, 2 )

// iterate over the list and print the data 
def cur @= head
repeat {
    if( cur ) { // checks for not empty tuple
        println( cur.data )
        cur @= cur.next
    } else {
        stop
    }
}

// NOTE: for longer running scripts it could be necessary to manual cleanup the list
//       after it is not needed anymore due to the cyclic references formed by prev/next.
//       But for short running scripts like this it is not necessary.

println( "END!" )