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 */
020package org.sonar.plugins.core.timemachine.tracking;
021
022/**
023 * Equivalence function for a {@link Sequence}.
024 */
025public interface SequenceComparator<S extends Sequence> {
026
027  /**
028   * Compare two items to determine if they are equivalent.
029   */
030  boolean equals(S a, int ai, S b, int bi);
031
032  /**
033   * Get a hash value for an item in a sequence.
034   *
035   * If two items are equal according to this comparator's
036   * {@link #equals(Sequence, int, Sequence, int)} method,
037   * then this hash method must produce the same integer result for both items.
038   * However not required to have different hash values for different items.
039   */
040  int hash(S seq, int i);
041
042}