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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.minisat.constraints;
29  
30  import org.sat4j.minisat.constraints.cnf.Clauses;
31  import org.sat4j.minisat.constraints.cnf.LearntHTClause;
32  import org.sat4j.minisat.constraints.cnf.Lits;
33  import org.sat4j.minisat.constraints.cnf.OriginalHTClause;
34  import org.sat4j.minisat.constraints.cnf.UnitClause;
35  import org.sat4j.minisat.core.Constr;
36  import org.sat4j.minisat.core.ILits;
37  import org.sat4j.specs.ContradictionException;
38  import org.sat4j.specs.IVecInt;
39  
40  /**
41   * Uses Head Tail data structure for both original clauses and learned clauses.
42   *
43   * @author leberre
44   */
45  public class ClausalDataStructureHT extends AbstractDataStructureFactory<ILits> {
46  
47      private static final long serialVersionUID = 1L;
48  
49      /*
50       * (non-Javadoc)
51       * 
52       * @see org.sat4j.minisat.DataStructureFactory#createClause(org.sat4j.datatype.VecInt)
53       */
54      public Constr createClause(IVecInt literals) throws ContradictionException {
55          IVecInt v = Clauses.sanityCheck(literals, getVocabulary(), solver);
56          if (v == null)
57              return null;
58          return OriginalHTClause.brandNewClause(solver, getVocabulary(), v);
59      }
60  
61      public Constr createUnregisteredClause(IVecInt literals) {
62      	if (literals.size()==1) {
63      		return new UnitClause(literals.last());
64      	}
65          return new LearntHTClause(literals, getVocabulary());
66      }
67  
68      @Override
69      protected ILits createLits() {
70          return new Lits();
71      }
72  }