6.92 MappedCollection

Defined in namespace Smalltalk

Category: Collections-Keyed

I represent collections of objects that are indirectly indexed by names. There are really two collections involved: domain and a map. The map maps between external names and indices into domain, which contains the real association. In order to work properly, the domain must be an instance of a subclass of SequenceableCollection, and the map must be an instance of Dictionary, or of a subclass of SequenceableCollection.

As an example of using me, consider implenting a Dictionary whose elements are indexed. The domain would be a SequenceableCollection with n elements, the map a Dictionary associating each key to an index in the domain. To access by key, to perform enumeration, etc. you would ask an instance of me; to access by index, you would access the domain directly.

Another idea could be to implement row access or column access to a matrix implemented as a single n*m Array: the Array would be the domain, while the map would be an Interval.

6.92.1 MappedCollection class: instance creation		(class)
6.92.2 MappedCollection: basic		(instance)

6.92.1 MappedCollection class: instance creation

collection: aCollection map: aMap

Answer a new MappedCollection using the given domain (aCollection) and map

new

This method should not be used; instead, use #collection:map: to create MappedCollection.

6.92.2 MappedCollection: basic

add: anObject

This method should not be called for instances of this class.

at: key

Answer the object at the given key

at: key put: value

Store value at the given key

collect: aBlock

Answer a MappedCollection with a copy of the receiver's map and a domain obtained by passing each object through aBlock

contents

Answer a bag with the receiver's values

do: aBlock

Evaluate aBlock for each object

domain

Answer the domain

map

Answer the map

reject: aBlock

Answer the objects in the domain for which aBlock returns false

select: aBlock

Answer the objects in the domain for which aBlock returns true

size

Answer the receiver's size