Class: MappedCollection

• Inheritance
• Description
• Class protocol
  • instance creation
• Instance protocol
  • accessing
  • adding & removing
  • copying-private
  • enumerating
  • private
  • queries
• Examples

Inheritance:

   Object
   |
   +--Collection
      |
      +--MappedCollection

Package:

stx:libbasic2

Category:

Collections-Sequenceable

Version:

rev: 1.25 date: 2019/08/12 08:48:19

user: cg

file: MappedCollection.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Author:

Claus Gittinger

Description:

MappedCollections 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 and map objects must
be instances of a subclass of SequenceableCollection or Dictionary.
The valueDomain of the map must be the keyDomain of the domain collection.
i.e. 
    mappedCollection at:k   ==>  domain at:(map at:k)

Class protocol:

 collection: domainCollection map: mapCollection

return a new MappedCollection

 new

report an error; mappedCollections may not be created using new

Instance protocol:

 at: key

retrieve an element

 at: key put: anObject

store an element

 contents

return the contents as a bag

 add: anObject

report an error; mappedCollections cannot add elements (without a key)

 postCopy

 do: aBlock

evaluate the argument, aBlock for each element

 setCollection: domainCollection map: mapCollection

 isFixedSize

return true if the receiver cannot grow

 size

return the number of elements in the receiver

 species

return the type of collection to be returned by collect, select etc.

 speciesForAdding

like species, but redefined for collections which cannot grow easily.
Used by functions which create a growing collection
(see collect:with:, for example)

Examples:

    |mapped keyMapping|

    keyMapping := Dictionary new
                at:'uno' put:1;
                at:'due' put:2;
                at:'tre' put:3;
                at:'quattro' put:4;
                yourself.

    mapped := MappedCollection
                    collection:#(one two three four)
                    map:keyMapping.

    mapped at:'tre'.
    mapped select:[:each| each ~= 'two']