1 /*******************************************************************************
2 * SAT4J: a SATisfiability library for Java Copyright (C) 2004-2008 Daniel Le Berre
3 *
4 * All rights reserved. This program and the accompanying materials
5 * are made available under the terms of the Eclipse Public License v1.0
6 * which accompanies this distribution, and is available at
7 * http://www.eclipse.org/legal/epl-v10.html
8 *
9 * Alternatively, the contents of this file may be used under the terms of
10 * either the GNU Lesser General Public License Version 2.1 or later (the
11 * "LGPL"), in which case the provisions of the LGPL are applicable instead
12 * of those above. If you wish to allow use of your version of this file only
13 * under the terms of the LGPL, and not to allow others to use your version of
14 * this file under the terms of the EPL, indicate your decision by deleting
15 * the provisions above and replace them with the notice and other provisions
16 * required by the LGPL. If you do not delete the provisions above, a recipient
17 * may use your version of this file under the terms of the EPL or the LGPL.
18 *
19 * Based on the original MiniSat specification from:
20 *
21 * An extensible SAT solver. Niklas Een and Niklas Sorensson. Proceedings of the
22 * Sixth International Conference on Theory and Applications of Satisfiability
23 * Testing, LNCS 2919, pp 502-518, 2003.
24 *
25 * See www.minisat.se for the original solver in C++.
26 *
27 *******************************************************************************/
28 package org.sat4j.core;
29
30 import java.io.Serializable;
31 import java.lang.reflect.InvocationTargetException;
32 import java.lang.reflect.Method;
33 import java.util.ArrayList;
34 import java.util.List;
35
36 import org.sat4j.specs.ISolver;
37
38 /**
39 * A solver factory is responsible for providing prebuilt solvers to the end
40 * user.
41 *
42 * @author bourgeois
43 */
44 public abstract class ASolverFactory<T extends ISolver> implements Serializable {
45
46 /**
47 *
48 */
49 private static final long serialVersionUID = 1L;
50
51 /**
52 * This methods returns names of solvers to be used with the method
53 * getSolverByName().
54 *
55 * @return an array containing the names of all the solvers available in the
56 * library.
57 * @see #createSolverByName(String)
58 */
59 public String[] solverNames() {
60 List<String> l = new ArrayList<String>();
61 Method[] solvers = this.getClass().getDeclaredMethods();
62 for (int i = 0; i < solvers.length; i++) {
63 if (solvers[i].getParameterTypes().length == 0
64 && solvers[i].getName().startsWith("new")) { //$NON-NLS-1$
65 l.add(solvers[i].getName().substring(3));
66 }
67 }
68 String[] names = new String[l.size()];
69 l.toArray(names);
70 return names;
71 }
72
73 /**
74 * create a solver from its String name. the solvername Xxxx must map one of
75 * the newXxxx methods.
76 *
77 * @param solvername
78 * the name of the solver
79 * @return an ISolver built using newSolvername. <code>null</code> if the
80 * solvername doesn't map one of the method of the factory.
81 */
82 @SuppressWarnings("unchecked")
83 public T createSolverByName(String solvername) {
84 try {
85 Class<?>[] paramtypes = {};
86 Method m = this.getClass()
87 .getMethod("new" + solvername, paramtypes); //$NON-NLS-1$
88 return (T) m.invoke(null, (Object[]) null);
89 } catch (SecurityException e) {
90 System.err.println(e.getLocalizedMessage());
91 } catch (IllegalArgumentException e) {
92 System.err.println(e.getLocalizedMessage());
93 } catch (NoSuchMethodException e) {
94 System.err.println(e.getLocalizedMessage());
95 } catch (IllegalAccessException e) {
96 System.err.println(e.getLocalizedMessage());
97 } catch (InvocationTargetException e) {
98 System.err.println(e.getLocalizedMessage());
99 }
100 return null;
101 }
102
103 /**
104 * To obtain the default solver of the library. The solver is suitable to
105 * solve huge SAT benchmarks. It should reflect state-of-the-art SAT
106 * technologies.
107 *
108 * For solving small/easy SAT benchmarks, use lightSolver() instead.
109 *
110 * @return a solver from the factory
111 * @see #lightSolver()
112 */
113 public abstract T defaultSolver();
114
115 /**
116 * To obtain a solver that is suitable for solving many small instances of
117 * SAT problems.
118 *
119 * The solver is not using sophisticated but costly reasoning and avoids to
120 * allocate too much memory.
121 *
122 * For solving bigger SAT benchmarks, use defaultSolver() instead.
123 *
124 * @return a solver from the factory
125 * @see #defaultSolver()
126 */
127 public abstract T lightSolver();
128 }