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.plugins.core.timemachine.tracking;
021    
022    /**
023     * Equivalence function for a {@link Sequence}.
024     */
025    public 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    }