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;
021    
022    import org.sonar.plugins.core.timemachine.tracking.HashedSequence;
023    import org.sonar.plugins.core.timemachine.tracking.HashedSequenceComparator;
024    import org.sonar.plugins.core.timemachine.tracking.StringText;
025    import org.sonar.plugins.core.timemachine.tracking.StringTextComparator;
026    
027    public class ViolationTrackingBlocksRecognizer {
028    
029      private final HashedSequence<StringText> a;
030      private final HashedSequence<StringText> b;
031      private final HashedSequenceComparator<StringText> cmp;
032    
033      public ViolationTrackingBlocksRecognizer(String referenceSource, String source) {
034        this(new StringText(referenceSource), new StringText(source), StringTextComparator.IGNORE_WHITESPACE);
035      }
036    
037      private ViolationTrackingBlocksRecognizer(StringText a, StringText b, StringTextComparator cmp) {
038        this.a = HashedSequence.wrap(a, cmp);
039        this.b = HashedSequence.wrap(b, cmp);
040        this.cmp = new HashedSequenceComparator<StringText>(cmp);
041      }
042    
043      /**
044       * @param startA number of line from first version of text (numbering starts from 0)
045       * @param startB number of line from second version of text (numbering starts from 0)
046       */
047      public int computeLengthOfMaximalBlock(int startA, int startB) {
048        if (!cmp.equals(a, startA, b, startB)) {
049          return 0;
050        }
051        int length = 0;
052        int ai = startA;
053        int bi = startB;
054        while (ai < a.length() && bi < b.length() && cmp.equals(a, ai, b, bi)) {
055          ai++;
056          bi++;
057          length++;
058        }
059        ai = startA;
060        bi = startB;
061        while (ai >= 0 && bi >= 0 && cmp.equals(a, ai, b, bi)) {
062          ai--;
063          bi--;
064          length++;
065        }
066        // Note that position (startA, startB) was counted twice
067        return length - 1;
068      }
069    
070    }