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'' BEGINNING OF HEADER INFO FOR LIST FUNCTIONS ''
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Const NULL As Any Ptr = 0

Type ListNode
    pdata As Any Ptr
    index As Integer
    prev_node As ListNode Ptr = NULL
    next_node As ListNode Ptr = NULL
End Type

Type List
    start_node As ListNode Ptr
    current_node As ListNode Ptr
    current_index As Integer
End Type

Declare Function ListCreate() As ListNode Ptr
Declare Function ListGetNode(pln As ListNode Ptr, index As Integer) As ListNode Ptr
Declare Function ListUBound(pln As ListNode Ptr) As Integer
Declare Function ListAddNodeToEnd(pln As ListNode Ptr) As ListNode Ptr
Declare Function ListGetLastNode(pln As ListNode Ptr) As ListNode Ptr
Declare Function ListRemoveNodeFromEnd(pln As ListNode Ptr) As ListNode Ptr
Declare Function ListRemoveNode(pln As ListNode Ptr, index As Integer) As ListNode Ptr
Declare Function ListInsertNode(pln As ListNode Ptr, index As Integer) As ListNode Ptr
Declare Function ListGetData(pln As ListNode Ptr, index As Integer) As Any Ptr
Declare Sub ListDestroy(pln As ListNode Ptr)

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'Test code here
Dim my_list As List

Dim i As Integer

'Create a list with 10 nodes with random integer data
Print "Create list..."
my_list.start_node = ListCreate()
Print "List created"

my_list.current_node = my_list.start_node

Print "Allocate Data to list..."
my_list.current_node->pdata = Allocate(SizeOf(Integer))
For i = 0 To 10
    my_list.current_node = ListAddNodeToEnd(my_list.start_node)
    my_list.current_node->pdata = Allocate(SizeOf(Integer))
    *CPtr(Integer Ptr, my_list.current_node->pdata) = i
Next

Print "Data allocated."
Sleep

For i = 0 To 10
    Print "Data in node: ", *CPtr(Integer Ptr, ListGetData(my_list.start_node, i))
Next

ListDestroy(my_list.start_node)
Sleep

'Function ListCreate()
Function ListCreate() As ListNode Ptr
    Dim t_pln As ListNode Ptr

    t_pln = Callocate(1, SizeOf(ListNode))
    Return t_pln
End Function

'Function ListGetNode
Function ListGetNode(pln As ListNode Ptr, index As Integer) As ListNode Ptr
    Dim t_pln As ListNode Ptr
    t_pln = pln
    While (t_pln->next_node <> NULL)
        If (t_pln->index = index) Then
            Return t_pln
        Else
            t_pln = t_pln->next_node
        EndIf
    Wend

    Return NULL
End Function

'Function ListUBound
Function ListUBound(pln As ListNode Ptr) As Integer
    Dim i As Integer
    Dim t_pln As ListNode Ptr
    t_pln = pln
    While (t_pln->next_node <> NULL)
        t_pln = t_pln->next_node
        i += 1
    Wend
    Return i
End Function

'Function ListAddNodeToEnd
Function ListAddNodeToEnd(pln As ListNode Ptr) As ListNode Ptr
    Dim last_pln As ListNode Ptr
    Dim new_pln As ListNode Ptr
    Print "test a"
    last_pln = ListGetLastNode(pln)
    Print "test b"
    new_pln = Callocate(1, SizeOf(ListNode))
    last_pln->next_node = new_pln
    new_pln->prev_node = last_pln
    new_pln->index = last_pln->index + 1

    Return new_pln
End Function

'Function ListGetLastNode
Function ListGetLastNode(pln As ListNode Ptr) As ListNode Ptr
    Dim last_node_i As Integer
    Dim t_pln As ListNode Ptr

    Print "test c"
    last_node_i = ListUBound(pln)
    Print "test d"
    t_pln = ListGetNode(pln, last_node_i)
    Print "test e"
    Return t_pln
End Function

'Function ListRemoveNodeFromEnd
Function ListRemoveNodeFromEnd(pln As ListNode Ptr) As ListNode Ptr
    Dim newlast_pln As ListNode Ptr
    Dim oldlast_pln As ListNode Ptr

    oldlast_pln = ListGetLastNode(pln)
    newlast_pln = oldlast_pln->prev_node
    DeAllocate(oldlast_pln->pdata)
    DeAllocate(oldlast_pln)
    newlast_pln->next_node = NULL

    Return newlast_pln
End Function

'Function ListRemoveNode
Function ListRemoveNode(pln As ListNode Ptr, index As Integer) As ListNode Ptr
    Dim t_pln As ListNode Ptr
    Dim prev_pln As ListNode Ptr
    Dim next_pln As ListNode Ptr

    'Get node at index
    t_pln = ListGetNode(pln, index)

    'Get the previous and next nodes in the structure
    prev_pln = t_pln->prev_node
    next_pln = t_pln->next_node

    'Delete this node's data
    DeAllocate(t_pln->pdata)

    'Delete this node
    DeAllocate(t_pln)

    'Set the next_node of the previous node to the next node
    prev_pln->next_node = next_pln

    'Set the prev_node of the next node to the previous node
    next_pln->prev_node = prev_pln

    'Set the current node to the next_pln
    t_pln = next_pln

    'Subtract the indices from every node following prev_pln by 1
    Do
        next_pln->index -= 1
        next_pln = next_pln->next_node
    Loop While (next_pln->next_node <> NULL)

    'Return t_pln, or current node at specified index
    Return t_pln
End Function


'Function ListInsertNode
Function ListInsertNode(pln As ListNode Ptr, index As Integer) As ListNode Ptr
    Dim new_pln As ListNode Ptr
    Dim t_pln As ListNode Ptr
    Dim prev_pln As ListNode Ptr
    Dim next_pln As ListNode Ptr

    'Get node at index
    t_pln = ListGetNode(pln, index)

    'Get previous and next nodes from it
    prev_pln = t_pln->prev_node
    next_pln = t_pln->next_node

    'Create new node to insert at index
    new_pln = Callocate(1, SizeOf(ListNode))

    'Fill in new node with node info
    new_pln->index = index
    new_pln->prev_node = prev_pln
    new_pln->next_node = next_pln

    'Fill in surrounding nodes with info on new node
    prev_pln->next_node = new_pln
    next_pln->prev_node = new_pln

    'Add one to all subsequent indices after the new node.
    Do
        next_pln->index += 1
        next_pln = next_pln->next_node
    Loop While(next_pln->next_node <> NULL)

    Return new_pln
End Function

'Function ListGetData
Function ListGetData(pln As ListNode Ptr, index As Integer) As Any Ptr
    Dim t_pln As ListNode Ptr
    t_pln = ListGetNode(pln, index)

    Return t_pln->pdata
End Function

'Sub ListDestroy
Sub ListDestroy(pln As ListNode Ptr)
    Dim i As Integer
    Dim t_pln As ListNode Ptr
    Dim t_pln2 As ListNode Ptr

    t_pln = pln
    Do
        DeAllocate(t_pln->pdata)
        If t_pln->next_node = NULL Then
            i = 1
        Else
            t_pln2 = t_pln
        EndIf
        DeAllocate(t_pln)
        t_pln = t_pln2
    Loop Until i = 1
End Sub