Extended Dictionary Class - for scripters

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Extended Dictionary Class - for scripters

Post by raybeau528 » Thu Feb 12, 2009 9:31 am

While working on my PlayTwo script, http://www.mediamonkey.com/forum/viewto ... =2&t=36591
I found it would be really helpful to iterate through a dictionary object with
the For Each/Next Loop as well as the For/Next loop and access items by their index position.
I created a wrapper Class and several of the methods/properties which allowed me to index through
the dictionary but didn't see how to implement the For Each loop with a class object. I found an extended dictionary class code on
the net which used the object property to return the dictionary object itself. It was also a
more elegant implementation so I used the basic class code and included additional properties
and methods. The class code is listed at the end. One caveat with using the index access method
is that it shouldn't be used with a numeric key. That would confuse it. Use some non-numeric key
if you're creating the key iteratively, ie something like "key" & i or "#" & i.

I hope you find this useful.

Class xDictionary extends the VBscript Dictionary object with these
additional methods and properties.

Object - Returns the actual dictionary object
Sort - Sorts the dictionary key-item pairs
UnSort - Randomizes the dictionary key-items pairs, can't use reserved keywords Random or Randomize
SortedKeys - Returns an array of sorted keys
UnSortedKeys - Returns an array of randomized keys
item(index) - returns the item at the ordinal position index
AddFromDictionary( dictionary object ) - Adds the key-item pairs from a dictionary object
LoadFromDictionary( dictionary object ) - Removes all key-item pairs then adds the key-item pairs
xKey(index) - returns the key from the ordinal position index

How to use:


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Dim oTestDB : Set oTestDB = CreateObject("Scripting.Dictionary")

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Dim oTestDB : Set oTestDB = New xDictionary

Sample code to demonstrate sort and unsort methods
Add items to the dictionary:

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Dim oTestDB	: Set oTestDB = New xDictionary
Dim sKey,i,a

Call oTEstDB.Add("C","Cat")
Call oTestDB.Add("A","Apple")
Call oTestDB.Add("B","Bat")
Sort the dictionary

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These two methods to iterate through the dictionary will
produce the same results. First, using a For Each loop:

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For each sKey in oTestDB.Object    ' note the use of the Object property
For / Next Loop:

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For i = 0 to oTest.DB.count-1
Randomizing the dictionary is just as easy:

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You can use the item(index) to set the value as well:

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or to remove an item

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Here's a more practical, working example using UnSort to Randomize a playlist:

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Sub RandomizePlaylist(arg)

	Dim i

	Dim oSongList 		: Set oSongList = SDB.CurrentSongList
	Dim oTrackList		: Set oTrackList = New xDictionary
	Dim oNewSongList	: Set oNewSongList = SDB.NewSongList
	Dim oCurrentNode	: Set oCurrentNode = SDB.MainTree.CurrentNode
	Dim oPlayList		: Set oPlayList = sdb.playlistbytitle( oCurrentNode.caption )

	If not (oCurrentNode.NodeType=61) Then
		Exit Sub
	End If

	' add each track to the dictionary
	For i = 0 to oSongList.count - 1
		If not (oTrackList.Exists(oSongList.Item(i).Title & oSongList.Item(i).ArtistName)) Then
			Call oTrackList.Add(oSongList.Item(i).Title & oSongList.Item(i).ArtistName, oSongList.Item(i))
		End If

	' Randomize the dictionary

	' Create an SDB.SongList of the randomized tracks 
	For i = 0 to oTrackList.Count-1

	' Clear the playlist and add back the sorted tracks
	Set oNewSongList = Nothing		
End Sub 
The PlayTwo script referred to above, uses the extended dictionary with
an item for each Artist and the item itself is a dictionary object
containing all tracks for that artist. With the extended dictionary it
was easy to randomize the artist as well as the tracks for each artist:

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		' randomize the artists
		For each sKey in TracksDB.Object
			' Randomize the tracks for this artist

Below is the code for the extended dictionary class.

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Class xDictionary
	'The actual dictionary that we will use
	Private oDict

	'Intialize event gets executed whenever an object is created
	Sub Class_Initialize()
		Set oDict = CreateObject("Scripting.Dictionary")
	End Sub

	'Executed when the object is destroyed
	Sub Class_Terminate()
		'Remove all the keys

		'Destroy the dictionary
		Set oDict = Nothing
	End Sub

	'Returns the actual dictionary object. This allows to do pass dictionary
	'to function which might support the actual dictionarty object such
	'as for each  key in xyz.object
	Public Function Object()
		Set Object = oDict
	End Function
	'Now we need add all functions that the Dictionary already supports
	Public Property Get HashVal(Text)
		HashVal = oDict.HashVal(Text)
	End Property

	'Method to add a Key Value Pair
	Public Sub Add(ByVal Key, ByVal Item)
		oDict.Add Key, Item
	End Sub

	'Return the array of keys
	Public Function Keys()
		Keys = oDict.Keys
	End Function

	'Return the array of keys sorted
	Public Function SortedKeys()
		SortedKeys = aSort(oDict.Keys)
	End Function
	'Return the array of keys Randomized
	Public Function unSortedKeys()
		UnSortedKeys = aRandom(oDict.Keys)
	End Function
	'Property to change key
	Public Property Let Key(oldKey, newKey)
		oDict.Key(oldKey) = newKey
	End Property

	'Returns array of items
	Public Function Items()
		Items = oDict.Items
	End Function

	'Check if certain key exists or not
	Public Function Exists(Key)
		Exists = oDict.Exists(Key)
	End Function

	'Remove All keys
	Public Sub RemoveAll()
	End Sub

	'Remove a specified key
	Public Sub Remove (Key)
		oDict.Remove GetKey(Key)
	End Sub

	'Get count of items in dictionary
	Public Property Get Count()
		Count = oDict.Count
	End Property

	'Get Property for CompareMode
	Public Property Get CompareMode()
		CompareMode = oDict.CompareMode
	End Property

	'Let Property for CompareMode
	Public Property Let CompareMode(newMode)
		oDict.CompareMode = newMode
	End Property
	' For testing purposes
	Public Property Get xKey(key)
		xKey = GetKey(key)
	End Property

	'Function to translate keys from Index to actual key
	Private Function GetKey(Key)
		'Return actual key in case we are not
		'able to translate index to key

		GetKey = Key

			If IsNumeric(Key) Then
				Dim KeyIndex
				keyIndex = CInt(Key)
				'Check if index is within range
				If keyIndex < Me.Count Then
					Dim aKeys
					aKeys = Me.Keys

					'Translate from Index to Key
					GetKey = aKeys(keyIndex)
					Exit Function
				End If
			End If

	End Function

	'Item is the Default property for dictionary. So we
	'need to use default keyword with Property Get
	'Default keyword can be used with a only one Function
	'or Get Property
	Public Default Property Get Item(Key)
		'If an object is stored for the Key
		'then we need to use Set to return the object
		If IsObject(oDict.Item(GetKey(Key))) Then
			Set Item = oDict.Item(GetKey(Key))
			Item = oDict.Item(GetKey(Key))
		End If
	End Property

	'Let property Item
	Public Property Let Item(Key, Value)
		'Check if the value is an object
		If IsObject(Value) Then
			'The value is an object, use the Set method
			Set oDict(GetKey(Key)) = Value
			'The value is not an object assign it
			oDict(GetKey(Key)) = Value
		End If
	End Property

	'Property Set Item
	Public Property Set Item(Key, Value)
		Set oDict(GetKey(Key)) = Value
	End Property
	' Rebuild the dictionary with sorted keys
	Public Sub Sort()
		Dim oTempDic : Set oTempDic = CreateObject("Scripting.Dictionary")
		Dim a,sKey
		a = me.SortedKeys
		For each sKey in a
			oTempDic.Add skey, oDict.item(sKey)
	End Sub
	' Rebuild the dictionary with Randomized keys - can't use Randomize keyword
	Public Sub unSort()
		Dim oTempDic : Set oTempDic = CreateObject("Scripting.Dictionary")
		Dim a,sKey
		a = me.UnsortedKeys
		For each sKey in a
			oTempDic.Add skey, oDict.item(sKey)
	End Sub
	' Simple Bubble Sort - could add a second param to indicate Ascending or Descending
	Private Function aSort(a)

		Dim i,j,temp,myArray
		for i = UBound(myArray) - 1 To 0 Step -1
			for j= 0 to i
				if myArray(j)>myArray(j+1) then		' change to >
				end if
	End Function ' Sort

	' Randomize Array  
	Private Function aRandom(a)

		Dim i,j,r,temp,myArray
		for i = 0 to Ubound(myArray)
			r=Int((Ubound(myArray) + 1) * Rnd)
	End Function

	'AddFromDictionary takes an actual dictionary object and
	'add all keys from it
	Public Sub AddFromDictionary(oldDict)
		Dim aKeys,sKey
		aKeys = oldDict.Keys

		For Each sKey In aKeys
			oDict.Add sKey, oldDict.item(sKey)
	End Sub

	'LoadFromDictionary function removes all keys
	'and then add the keys from dictionary. It is
	'equivalent of creating a clone from a existing
	'dictionarty object
	Public Sub LoadFromDictionary(oldDict)
		Me.AddFromDictionary oldDict
	End Sub

End Class