Package net.cscott.jutil

Class Indexer<T>

java.lang.Object
net.cscott.jutil.Indexer<T>
public abstract class Indexer<T> extends Object
Indexer is an object for extracting unique indices for a set of objects. It is commonly generated by Factories for some class of objects, which can then generate and store unique integers in the objects that they are used to construct. This way auxilliary data structures can efficiently index objects that belong to a common Factory without that data-structure needing an explict dependency on that particular Factory or Object type.
Author:
Felix S. Klock II <pnkfelix@mit.edu>

  • Constructor Details

    • Indexer

      public Indexer()

  • Method Details

    • getID

      public abstract int getID(T o)
      Returns the "small" integer uniquely associated with o in this.
      requires: o is a member of the set of objects indexed by this
      effects: returns the integer uniquely associated with o from a densely-packed, non-negative set of integers whose smallest element is close to zero.

    • getByID

      public T getByID(int id)
      Provides a reverse mapping for the index returned by getID. The constraint is that getByID(getID(o)) must equal o for all objects indexed by this.
      Throws:
      UnsupportedOperationException - if this functionality is not supported by this.

    • implementsReverseMapping

      public boolean implementsReverseMapping()
      Tells user whether this particular Indexer implements the getByID() method.