001 package aima.search.framework;
002
003 import aima.search.framework.Search;
004 import aima.search.framework.GraphSearch;
005 import aima.search.framework.TreeSearch;
006 import aima.search.framework.QueueSearch;
007 import aima.search.informed.AStarEvaluationFunction;
008 import aima.search.informed.AStarSearch;
009 import aima.search.informed.GreedyBestFirstSearch;
010 import aima.search.informed.HillClimbingSearch;
011 import aima.search.informed.RecursiveBestFirstSearch;
012 import aima.search.uninformed.BreadthFirstSearch;
013 import aima.search.uninformed.DepthFirstSearch;
014 import aima.search.uninformed.IterativeDeepeningSearch;
015 import aima.search.uninformed.UniformCostSearch;
016
017 /**
018 * Useful factory for configuring search objects. Implemented
019 * as a singleton.
020 * @author R. Lunde
021 */
022 public class SearchFactory {
023
024 /** Search strategy: Depth first search. */
025 public final static int DF_SEARCH = 0;
026 /** Search strategy: Depth first search. */
027 public final static int BF_SEARCH = 1;
028 /** Search strategy: Iterative deepening search. */
029 public final static int ID_SEARCH = 2;
030 /** Search strategy: Uniform cost search. */
031 public final static int UC_SEARCH = 3;
032 /** Search strategy: Greedy best first search. */
033 public final static int GBF_SEARCH = 4;
034 /** Search strategy: A* search. */
035 public final static int ASTAR_SEARCH = 5;
036 /** Search strategy: Recursive best first search. */
037 public final static int RBF_SEARCH = 6;
038 /** Search strategy: Hill climbing search. */
039 public final static int HILL_SEARCH = 7;
040
041 /** Search mode: tree search. */
042 public final static int TREE_SEARCH = 0;
043 /** Search mode: graph search. */
044 public final static int GRAPH_SEARCH = 1;
045
046 /** Contains the only existing instance. */
047 private static SearchFactory instance;
048 /** Invisible constructor. */
049 private SearchFactory() {};
050
051 /** Provides access to the factory. Implemented with lazy instantiation. */
052 public static SearchFactory getInstance() {
053 if (instance == null)
054 instance = new SearchFactory();
055 return instance;
056 }
057
058 /**
059 * Returns the names of all search strategies, which are supported
060 * by this factory. The indices correspond to the parameter values
061 * of method {@link #createSearch(int, int)}.
062 */
063 public String[] getSearchStrategyNames() {
064 return new String[]{
065 "Depth First", "Breadth First", "Iterative Deepening",
066 "Uniform Cost", "Greedy Best First", "A*",
067 "Recursive Best First", "Hill Climbing"};
068 }
069
070 /**
071 * Returns the names of all search modes, which are supported
072 * by this factory. The indices correspond to the parameter values
073 * of method {@link #createSearch(int, int)}.
074 */
075 public String[] getSearchModeNames() {
076 return new String[]{"Tree Search", "Graph Search"};
077 }
078
079 /**
080 * Creates a search instance.
081 * @param strategy search strategy. See static constants.
082 * @param mode search mode: {@link #TREE_SEARCH} or {@link #GRAPH_SEARCH}
083 *
084 */
085 public Search createSearch(int strategy, int mode) {
086 QueueSearch qs = null;
087 Search result = null;
088 switch(mode) {
089 case TREE_SEARCH: qs = new TreeSearch(); break;
090 case GRAPH_SEARCH: qs = new GraphSearch();
091 }
092 switch (strategy) {
093 case DF_SEARCH:
094 result = new DepthFirstSearch(qs); break;
095 case BF_SEARCH:
096 result = new BreadthFirstSearch(qs); break;
097 case ID_SEARCH:
098 result = new IterativeDeepeningSearch(); break;
099 case UC_SEARCH:
100 result = new UniformCostSearch(qs); break;
101 case GBF_SEARCH:
102 result = new GreedyBestFirstSearch(qs); break;
103 case ASTAR_SEARCH:
104 result = new AStarSearch(qs); break;
105 case RBF_SEARCH:
106 result = new RecursiveBestFirstSearch(new AStarEvaluationFunction()); break;
107 case HILL_SEARCH:
108 result = new HillClimbingSearch(); break;
109 }
110 return result;
111 }
112 }