Generic BaseList

[empty]

This is a generic baselist loosely based on Kevin's generic list example

It's got a few more functions like inserting items, getting and setting the position and so on.
The main difference to it (and also to the built-in linked list) is that items are stored the other way around (aka the right way ;)), that means the first item in the list is the first that you've added.
Similar to the built in list, it's based on a "current item" approach. Basically you have a pointer that points at the current item and remove/insert operations are based on this. However, there's an example of a string list that shows how to do an index-based list. It's certainly buggy (and does crash here with larger amounts of items).

Anyway, this will become the base of a generic list, which in turn will become the base of a generic tree node system, which in turn will become the base of a native XML library.

PlayBASIC Code: [Select]

; PROJECT : BaseList
; CREATED : 25.04.2008
; EDITED  : 26.04.2008
; ---------------------------------------------------------------------

Explicit

Type TBaseListManager
   FirstItem As Integer
   ItemCount As Integer
   CurrentItem As Integer
   LastItem As Integer
EndType

Type TBaseList
   NextItem As Integer ;  As TBaseList Pointer
   PrevItem As Integer ;  As TBaseList Pointer
   ItemType As Integer
EndType

Dim _BaseListManager(1) As TBaseListManager


Function CreateBaseList()
   Local result = GetFreeCell(_BaseListManager())   
   _BaseListManager(result).FirstItem = 0
   _BaseListManager(result).LastItem = 0
   _BaseListManager(result).ItemCount = 0
EndFunction result

Function GetBaseListFirstItem(Handle)
   Dim result As Integer
   If Handle > 0 And Handle <= GetArrayElements(_BaseListManager(),1)
      result = _BaseListManager(Handle).FirstItem
   EndIf
EndFunction result


Function GetBaseListNextItem(Handle)
   If Handle < 1 Or Handle > GetArrayElements(_BaseListManager(),1)
      Exitfunction 0
   EndIf
   Dim CurrentItem As TBaseList Pointer
   Dim Result As TBaseList Pointer
   
   CurrentItem = _BaseListManager(Handle).CurrentItem
   Result = CurrentItem.NextItem
EndFunction Result As TBaseList Pointer


Function GetBaseListPrevItem(Handle)
   If Handle < 1 Or Handle > GetArrayElements(_BaseListManager(),1)
      Exitfunction
   EndIf
   Dim CurrentItem As TBaseList Pointer
   Dim Result As TBaseList Pointer
   
   CurrentItem = _BaseListManager(Handle).CurrentItem
   Result = CurrentItem.PrevItem
EndFunction Result As TBaseList Pointer


Function SetBaseListCurrentToLast(Handle)
   If Handle < 1 Or Handle > GetArrayElements(_BaseListManager(),1)
      Exitfunction NULL
   EndIf   
   Dim result As TBaseList Pointer
   _BaseListManager(Handle).CurrentItem = _BaseListManager(Handle).LastItem
   result = _BaseListManager(Handle).LastItem
EndFunction result As TBaseList Pointer
   
      
Function SetBaseListCurrentToFirst(Handle)
   If Handle < 1 Or Handle > GetArrayElements(_BaseListManager(),1)
      Exitfunction NULL
   EndIf   
   Dim result As TBaseList Pointer
   _BaseListManager(Handle).CurrentItem = _BaseListManager(Handle).FirstItem
   result = _BaseListManager(Handle).FirstItem
EndFunction result As TBaseList Pointer

Function SetBaseListCurrentPos(Handle, Pos)
   If Handle < 1 Or Handle > GetArrayElements(_BaseListManager(),1)
      Exitfunction NULL
   EndIf   
   If Pos < 1 Or Pos > _BaseListManager(Handle).ItemCount
      Exitfunction NULL
   EndIf
   Local thispos = 1
   Dim thisitem As TBaseList Pointer
   _BaseListManager(Handle).CurrentItem = _BaseListManager(Handle).FirstItem
   While thisPos < Pos
      thisitem = _BaseListManager(Handle).CurrentItem
      thisitem = thisitem.NextItem      
      _BaseListManager(Handle).CurrentItem = Int(thisitem)
      Inc thispos
   EndWhile
      
EndFunction _BaseListManager(Handle).CurrentItem

Function GetBaseListCurrentPos(Handle)
   If Handle < 1 Or Handle > GetArrayElements(_BaseListManager(),1)
      Exitfunction 0
   EndIf   
   Local result = 1
   Dim thisitem As TBaseList Pointer
   Dim tmpItem As TBaseList Pointer
   thisitem = _BaseListManager(Handle).FirstItem
   While Int(thisitem) <> _BaseListManager(Handle).CurrentItem
      Inc result
      If Int(thisitem) = NULL Then Exitfunction 0
      thisitem = thisitem.NextItem
   EndWhile        
EndFunction result

Function GetBaseListCurrentItem(Handle)   
   If Handle < 1 Or Handle > GetArrayElements(_BaseListManager(),1)
      Exitfunction 0
   EndIf
   Dim Result As TBaseList Pointer
   
   Result = _BaseListManager(Handle).CurrentItem
EndFunction Result As TBaseList Pointer



Function AddToBaseList(Handle, Me As TBaseList Pointer)
   If Handle < 1 Or Handle > GetArrayElements(_BaseListManager(),1)
      Exitfunction
   EndIf
   Local Result = 0
   Dim NextItem As TBaseList Pointer
   Me.NextItem = 0
   
   If _BaseListManager(Handle).LastItem <> 0
      NextItem = _BaseListManager(Handle).LastItem 
      NextItem.NextItem = Int(Me)
   Else
      _BaseListManager(Handle).FirstItem = Int(Me)    
   EndIf
      
   Me.PrevItem = _BaseListManager(Handle).LastItem

   _BaseListManager(Handle).LastItem =Int(Me)

   _BaseListManager(Handle).CurrentItem = Int(Me)
   _BaseListManager(Handle).ItemCount = _BaseListManager(Handle).ItemCount + 1   
   Result = _BaseListManager(Handle).ItemCount   
EndFunction result

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