org.spearce.jgit/src/org/spearce/jgit/merge/StrategyOneSided.java

   1 /*
   2  * Copyright (C) 2008, Google Inc.
   3  *
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or
   7  * without modification, are permitted provided that the following
   8  * conditions are met:
   9  *
  10  * - Redistributions of source code must retain the above copyright
  11  *   notice, this list of conditions and the following disclaimer.
  12  *
  13  * - Redistributions in binary form must reproduce the above
  14  *   copyright notice, this list of conditions and the following
  15  *   disclaimer in the documentation and/or other materials provided
  16  *   with the distribution.
  17  *
  18  * - Neither the name of the Git Development Community nor the
  19  *   names of its contributors may be used to endorse or promote
  20  *   products derived from this software without specific prior
  21  *   written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  24  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  25  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  28  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  29  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  31  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  32  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  33  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  35  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 package org.spearce.jgit.merge;
  39
  40 import java.io.IOException;
  41
  42 import org.spearce.jgit.lib.ObjectId;
  43 import org.spearce.jgit.lib.Repository;
  44
  45 /**
  46  * Trivial merge strategy to make the resulting tree exactly match an input.
  47  * <p>
  48  * This strategy can be used to cauterize an entire side branch of history, by
  49  * setting the output tree to one of the inputs, and ignoring any of the paths
  50  * of the other inputs.
  51  */
  52 public class StrategyOneSided extends MergeStrategy {
  53         private final String strategyName;
  54
  55         private final int treeIndex;
  56
  57         /**
  58          * Create a new merge strategy to select a specific input tree.
  59          *
  60          * @param name
  61          *            name of this strategy.
  62          * @param index
  63          *            the position of the input tree to accept as the result.
  64          */
  65         protected StrategyOneSided(final String name, final int index) {
  66                 strategyName = name;
  67                 treeIndex = index;
  68         }
  69
  70         @Override
  71         public String getName() {
  72                 return strategyName;
  73         }
  74
  75         @Override
  76         public Merger newMerger(final Repository db) {
  77                 return new OneSide(db, treeIndex);
  78         }
  79
  80         protected static class OneSide extends Merger {
  81                 private final int treeIndex;
  82
  83                 protected OneSide(final Repository local, final int index) {
  84                         super(local);
  85                         treeIndex = index;
  86                 }
  87
  88                 @Override
  89                 protected boolean mergeImpl() throws IOException {
  90                         return treeIndex < sourceTrees.length;
  91                 }
  92
  93                 @Override
  94                 public ObjectId getResultTreeId() {
  95                         return sourceTrees[treeIndex];
  96                 }
  97         }
  98 }