orbital.algorithm.template
Class BestFirstSearch.OptionIterator

java.lang.Object
  orbital.algorithm.template.GeneralSearch.OptionIterator
      orbital.algorithm.template.BestFirstSearch.OptionIterator

All Implemented Interfaces:

java.io.Serializable, java.util.Iterator

Enclosing class:

BestFirstSearch

public static class BestFirstSearch.OptionIterator
extends GeneralSearch.OptionIterator

An iterator over a state space in best-first order. Expands nodes with better f-costs, first.

Author:

André Platzer

See Also:

Serialized Form

Invariants:

isSorted(nodes)

Constructor Summary

BestFirstSearch.OptionIterator(GeneralSearchProblem problem, Function evaluation)

Method Summary

protected boolean	add(java.util.Iterator newNodes) merge old and new lists.
protected boolean	isEmpty() Returns true if this iterator's collection of nodes currently does not contain any elements.
protected java.lang.Object	select() Select the node with min f(n).

Methods inherited from class orbital.algorithm.template.GeneralSearch.OptionIterator

getProblem, hasNext, next, remove

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BestFirstSearch.OptionIterator

public BestFirstSearch.OptionIterator(GeneralSearchProblem problem,
                                      Function evaluation)

Parameters:

evaluation - the evaluation function to use for sorting the options monotonically. Usually EvaluativeAlgorithm.getEvaluation().

Method Detail

isEmpty

protected boolean isEmpty()

Description copied from class: GeneralSearch.OptionIterator

Returns true if this iterator's collection of nodes currently does not contain any elements.

Specified by:

isEmpty in class GeneralSearch.OptionIterator

Returns:

true if this collection contains no elements.

select

protected java.lang.Object select()

Select the node with min f(n). Due to the sorted list that is the first object.

Specified by:

select in class GeneralSearch.OptionIterator

Returns:

the selected option after removing it from nodes.

Preconditions:

sorted(nodes)

add

protected boolean add(java.util.Iterator newNodes)

merge old and new lists.

Specified by:

add in class GeneralSearch.OptionIterator

Parameters:

newNodes - the new nodes we apparently became aware of. (Might be modified by this method).

Returns:

true if nodes changed as a result of the call.

See Also:

Setops.merge(List, List, Comparator)

Preconditions:

sorted(nodes)

Postconditions:

sorted(nodes)