| /* |
| * Copyright (C) 2010, Google Inc. |
| * and other copyright owners as documented in the project's IP log. |
| * |
| * This program and the accompanying materials are made available |
| * under the terms of the Eclipse Distribution License v1.0 which |
| * accompanies this distribution, is reproduced below, and is |
| * available at http://www.eclipse.org/org/documents/edl-v10.php |
| * |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or |
| * without modification, are permitted provided that the following |
| * conditions are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * - Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer in the documentation and/or other materials provided |
| * with the distribution. |
| * |
| * - Neither the name of the Eclipse Foundation, Inc. nor the |
| * names of its contributors may be used to endorse or promote |
| * products derived from this software without specific prior |
| * written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
| * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
| * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
| * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| package org.eclipse.jgit.diff; |
| |
| /** |
| * Wraps two {@link Sequence} instances to cache their element hash codes. |
| * <p> |
| * This pair wraps two sequences that contain cached hash codes for the input |
| * sequences. |
| * |
| * @param <S> |
| * the base sequence type. |
| */ |
| public class HashedSequencePair<S extends Sequence> { |
| private final SequenceComparator<? super S> cmp; |
| |
| private final S baseA; |
| |
| private final S baseB; |
| |
| private HashedSequence<S> cachedA; |
| |
| private HashedSequence<S> cachedB; |
| |
| /** |
| * Construct a pair to provide fast hash codes. |
| * |
| * @param cmp |
| * the base comparator for the sequence elements. |
| * @param a |
| * the A sequence. |
| * @param b |
| * the B sequence. |
| */ |
| public HashedSequencePair(SequenceComparator<? super S> cmp, S a, S b) { |
| this.cmp = cmp; |
| this.baseA = a; |
| this.baseB = b; |
| } |
| |
| /** @return obtain a comparator that uses the cached hash codes. */ |
| public HashedSequenceComparator<S> getComparator() { |
| return new HashedSequenceComparator<S>(cmp); |
| } |
| |
| /** @return wrapper around A that includes cached hash codes. */ |
| public HashedSequence<S> getA() { |
| if (cachedA == null) |
| cachedA = wrap(baseA); |
| return cachedA; |
| } |
| |
| /** @return wrapper around B that includes cached hash codes. */ |
| public HashedSequence<S> getB() { |
| if (cachedB == null) |
| cachedB = wrap(baseB); |
| return cachedB; |
| } |
| |
| private HashedSequence<S> wrap(S base) { |
| final int end = base.size(); |
| final int[] hashes = new int[end]; |
| for (int ptr = 0; ptr < end; ptr++) |
| hashes[ptr] = cmp.hash(base, ptr); |
| return new HashedSequence<S>(base, hashes); |
| } |
| } |