Overview
Unlike other programming languages, VBScript lacks support of complex data structures. Sometimes this makes life a bit difficult. We need to code our own algorithms to achieve simple tasks like sorting or reversing an array. .NET has support for complex data structures which come with built-in functions for these simple tasks. So if we can use .NET data structure then we can eliminate the reinvention of the wheel for some of these tasks. Well, the good news is that some .NET libraries are exposed to COM and can be used in VBScript. Let’s take a look at the most useful of these…
ArrayList
An ArrayList is an array whose size is dynamically increased when needed. Here is an example of its use:
Set objArrayList = CreateObject("System.Collections.ArrayList")
objArrayList.Add 6
objArrayList.Add 8
objArrayList.Add 2
objArrayList.Add 4
objArrayList.Add 1
objArrayList.Add 5
objArrayList.Add 3
objArrayList.Add 3
objArrayList.Add 7
'Convert to VBScript Array
Rhino.Print Join(objArrayList.ToArray, ",")
'Return the element at a given index
Rhino.Print objArrayList(0)
'Return the number of elements
Rhino.Print objArrayList.Count
'Verifies an element exists or not.
Rhino.Print objArrayList.Contains(5)
'Sort the elements
objArrayList.Sort
Rhino.Print Join(objArrayList.ToArray, ",")
'Reverse the order of all elements
objArrayList.Reverse
Rhino.Print Join(objArrayList.ToArray, ",")
'Remove a specific element
objArrayList.Remove 8
'Remove element by index
objArrayList.RemoveAt 6
'Remove all elements
objArrayList.Clear
For VBScript Dictionary objects we don’t need to redim while appending or removing elements. Also, an element can be directly searched without iterating through each of them. Both of these features are available with ArrayList as well but one of the most important dictionary object features, Key-Value pair, is not in ArrayList. SortedList is an alternative if you want the power of both ArrayList and Dictionary.
SortedList
A SortedList a is sorted Dictionary. Every time we add or remove a key value pair in the dictionary, it automatically gets sorted by Key. You can also access elements based on its index (just like arrays) which makes this even more powerful. Here is an example:
Set objSortedList = CreateObject("System.Collections.SortedList")
objSortedList.Add "Point", 1
objSortedList.Add "Point Cloud", 2
objSortedList.Add "Curve", 4
objSortedList.Add "Surface", 8
objSortedList.Add "Polysurface", 16
objSortedList.Add "Mesh", 32
'Return the number of elements
Rhino.Print objSortedList.Count
'Return a value by its key
Rhino.Print objSortedList("Surface")
'Access all elements by index
For i = 0 To objSortedList.Count - 1
Rhino.Print CStr(objSortedList.GetByIndex(i))
Next
'Verify a key exists
Rhino.Print objSortedList.ContainsKey("Polysurface")
'Verify a value exists
Rhino.Print objSortedList.ContainsValue(16)
'Return the index by key (zero based index)
Rhino.Print objSortedList.IndexOfKey("Polysurface")
'Return the index by value
Rhino.Print objSortedList.IndexOfValue(16)
'Remove an element by key
objSortedList.Remove "Polysurface"
'Remove an element by index
objSortedList.RemoveAt 0
'Remove all elements
objSortedList.Clear
Stack
A Stack is a simple last-in, first-out (LIFO) non-generic collection of objects or data. By last-in, first-out, what we mean is if a set of objects is put into a stack, the last object that was put in will be the first object to be taken out. For example, in a restaurants with an automatic plate dispenser, the stack of plates are added to from the top. As each person takes a plate, the next plate in the stack becomes available. Here is an example of using Stack:
Set objStack = CreateObject("System.Collections.Stack")
'Add elements to stack
objStack.Push "Item_1"
objStack.Push "Item_2"
objStack.Push "Item_3"
objStack.Push "Item_4"
'Iterate through each element
For Each Item In objStack
Rhino.Print Item
Next
'Convert to VBScript array
Rhino.Print Join(objStack.ToArray, ",")
'Return the number of elements
Rhino.Print objStack.Count
'Verify an element exists
Rhino.Print objStack.Contains("Item_2")
'Pop the last element
Rhino.Print objStack.Pop
'Return the last in element without popping
Rhino.Print objStack.Peek
Rhino.Print objStack.Pop
Rhino.Print objStack.Pop
'Remove all elements
objStack.Clear
Queue
Unlike a Stack, a Queue represents a first-in, first-out collection of objects or data. Here is an example:
Set objQueue = CreateObject("System.Collections.Queue")
'Add elements to queue
objQueue.Enqueue "Item_1"
objQueue.Enqueue "Item_2"
objQueue.Enqueue "Item_3"
objQueue.Enqueue "Item_4"
'Iterate through each element
For Each Item In objQueue
Rhino.Print Item
Next
'Convert to VBScript array
Rhino.Print Join(objQueue.ToArray, ",")
'Return the number of elements
Rhino.Print objQueue.Count
'Verify an element exists
Rhino.Print objQueue.Contains("Item_2")
'Return the first element
Rhino.Print objQueue.Dequeue
'Return the first element without removing it
Rhino.Print objQueue.Peek
Rhino.Print objQueue.Dequeue
Rhino.Print objQueue.Dequeue
'Removes all elements
objQueue.Clear
