MoveObjectUp and MoveObjectDown

This code has been declared by its author to be Public Domain code.

MoveObjectUp and MoveObjectDown by plash

2008

Code example in comments!

Function MoveObjectUp:Int(list:TList, obj:Object)
  Local link:TLink, prev:TLink
	
	If list.Count() = 0 Then Return False
	
	link = list.FindLink(obj)
	If link = Null Then Return False
	
	prev = link.PrevLink()
	If prev = Null Then Return False ' Already at the top of the list
	
	link = Null
	list.Remove(obj)
	list.InsertBeforeLink(obj, prev)
	
	Return True
	
End Function

Function MoveObjectDown:Int(list:TList, obj:Object)
  Local link:TLink, nextlink:TLink
	
	If list.Count() = 0 Then Return False
	
	link = list.FindLink(obj)
	If link = Null Then Return False
	
	nextlink = link.NextLink()
	If nextlink = Null Then Return False ' Already at the bottom of the list
	
	link = Null
	list.Remove(obj)
	list.InsertAfterLink(obj, nextlink)
	
	Return True
	
End Function

Comments

plash

2008

Example code:

SuperStrict

Framework brl.standardio
Import brl.linkedlist

Local mylist:TList = New(TList)

Local myfirstobject:String = "Hello"
Local mysecondobject:String = "World!"
mylist.AddLast(myfirstobject)
mylist.AddLast(mysecondobject)
mylist.AddLast(":P")

Print "Moved: " + MoveObjectUp(mylist, mysecondobject)
Print "Moved: " + MoveObjectDown(mylist, myfirstobject)

For Local value:String = EachIn mylist
	
	Print "~q" + value + "~q"
	
Next
End

Function MoveObjectUp:Int(list:TList, obj:Object)
  Local link:TLink, prev:TLink
	
	If list.Count() = 0 Then Return False
	
	link = list.FindLink(obj)
	If link = Null Then Return False
	
	prev = link.PrevLink()
	If prev = Null Then Return False ' Already at the top of the list
	
	link = Null
	list.Remove(obj)
	list.InsertBeforeLink(obj, prev)
	
	Return True
	
End Function

Function MoveObjectDown:Int(list:TList, obj:Object)
  Local link:TLink, nextlink:TLink
	
	If list.Count() = 0 Then Return False
	
	link = list.FindLink(obj)
	If link = Null Then Return False
	
	nextlink = link.NextLink()
	If nextlink = Null Then Return False ' Already at the bottom of the list
	
	link = Null
	list.Remove(obj)
	list.InsertAfterLink(obj, nextlink)
	
	Return True
	
End Function

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