001package net.sf.cpsolver.ifs.model; 002 003import net.sf.cpsolver.ifs.model.Model; 004import net.sf.cpsolver.ifs.model.Value; 005import net.sf.cpsolver.ifs.model.Variable; 006 007/** 008 * Lazy swap of two variables. See {@link LazyNeighbour}. 009 * 010 * @version IFS 1.2 (Iterative Forward Search)<br> 011 * Copyright (C) 2013 Tomáš Müller<br> 012 * <a href="mailto:muller@unitime.org">muller@unitime.org</a><br> 013 * <a href="http://muller.unitime.org">http://muller.unitime.org</a><br> 014 * <br> 015 * This library is free software; you can redistribute it and/or 016 * modify it under the terms of the GNU Lesser General Public 017 * License as published by the Free Software Foundation; either 018 * version 3 of the License, or (at your option) any later version. 019 * <br><br> 020 * This library is distributed in the hope that it will be useful, 021 * but WITHOUT ANY WARRANTY; without even the implied warranty of 022 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 023 * Lesser General Public License for more details. 024 * <br><br> 025 * You should have received a copy of the GNU Lesser General Public 026 * License along with this library; if not see 027 * <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>. 028 */ 029public class LazySwap<V extends Variable<V, T>, T extends Value<V, T>> extends LazyNeighbour<V, T> { 030 private T iV1, iV2, iOldV1, iOldV2; 031 032 /** 033 * Constructor 034 * @param v1 first variable 035 * @param v2 second variable 036 */ 037 public LazySwap(T v1, T v2) { 038 iV1 = v1; 039 iV2 = v2; 040 iOldV1 = v1.variable().getAssignment(); 041 iOldV2 = v2.variable().getAssignment(); 042 } 043 044 /** Perform swap */ 045 @Override 046 protected void doAssign(long iteration) { 047 if (iOldV1!=null) iOldV1.variable().unassign(iteration); 048 if (iOldV2!=null) iOldV2.variable().unassign(iteration); 049 iV1.variable().assign(iteration, iV1); 050 iV2.variable().assign(iteration, iV2); 051 } 052 053 /** Undo the swap */ 054 @Override 055 protected void undoAssign(long iteration) { 056 iV1.variable().unassign(iteration); 057 iV2.variable().unassign(iteration); 058 if (iOldV1!=null) iOldV1.variable().assign(iteration, iOldV1); 059 if (iOldV2!=null) iOldV2.variable().assign(iteration, iOldV2); 060 } 061 /** Return problem model */ 062 @Override 063 public Model<V,T> getModel() { 064 return iV1.variable().getModel(); 065 } 066 067 /** String representation */ 068 @Override 069 public String toString() { 070 return "Lazy "+iOldV1+" -> "+iV1+", "+iOldV2+" -> "+iV2; 071 } 072 073}