001 /* 002 * Sonar, open source software quality management tool. 003 * Copyright (C) 2008-2012 SonarSource 004 * mailto:contact AT sonarsource DOT com 005 * 006 * Sonar is free software; you can redistribute it and/or 007 * modify it under the terms of the GNU Lesser General Public 008 * License as published by the Free Software Foundation; either 009 * version 3 of the License, or (at your option) any later version. 010 * 011 * Sonar is distributed in the hope that it will be useful, 012 * but WITHOUT ANY WARRANTY; without even the implied warranty of 013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 * Lesser General Public License for more details. 015 * 016 * You should have received a copy of the GNU Lesser General Public 017 * License along with Sonar; if not, write to the Free Software 018 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02 019 */ 020 package org.sonar.graph; 021 022 public final class DsmTopologicalSorter<V> { 023 024 private final Dsm<V> dsm; 025 private int leftOrderedIndex; 026 private int rightOrderedIndex; 027 028 private DsmTopologicalSorter(Dsm<V> dsm) { 029 this.dsm = dsm; 030 leftOrderedIndex = 0; 031 rightOrderedIndex = dsm.getDimension() - 1; 032 } 033 034 public static <V> void sort(Dsm<V> dsm) { 035 DsmTopologicalSorter<V> partitionner = new DsmTopologicalSorter<V>(dsm); 036 boolean dsmCanBeSorted = true; 037 while (dsmCanBeSorted) { 038 boolean dsmCanBeSortedOnLeft = partitionner.pushToLeftVerticesWithoutIncomingEdges(); 039 boolean dsmCanBeSortedOnRight = partitionner.pushToRightVerticesWithoutOutgointEdges(); 040 dsmCanBeSorted = dsmCanBeSortedOnLeft || dsmCanBeSortedOnRight; 041 } 042 boolean isCyclicGraph = (partitionner.leftOrderedIndex < partitionner.rightOrderedIndex); 043 if (isCyclicGraph) { 044 throw new IllegalStateException("Can't sort a cyclic graph."); 045 } 046 } 047 048 private boolean pushToLeftVerticesWithoutIncomingEdges() { 049 boolean permutationsDone = false; 050 for (int i = leftOrderedIndex; i <= rightOrderedIndex; i++) { 051 if (dsm.getNumberOfIncomingEdges(i, leftOrderedIndex, rightOrderedIndex) == 0) { 052 dsm.permute(i, leftOrderedIndex); 053 leftOrderedIndex++; 054 permutationsDone = true; 055 } 056 } 057 return permutationsDone; 058 } 059 060 private boolean pushToRightVerticesWithoutOutgointEdges() { 061 boolean permutationsDone = false; 062 for (int i = leftOrderedIndex; i <= rightOrderedIndex; i++) { 063 if (dsm.getNumberOfOutgoingEdges(i, leftOrderedIndex, rightOrderedIndex) == 0) { 064 dsm.permute(i, rightOrderedIndex); 065 rightOrderedIndex--; 066 permutationsDone = true; 067 } 068 } 069 return permutationsDone; 070 } 071 }