| /* |
| * Copyright (C) 2010, Google Inc. and others |
| * |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Distribution License v. 1.0 which is available at |
| * https://www.eclipse.org/org/documents/edl-v10.php. |
| * |
| * SPDX-License-Identifier: BSD-3-Clause |
| */ |
| |
| package org.eclipse.jgit.diff; |
| |
| /** |
| * Wraps two {@link org.eclipse.jgit.diff.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; |
| } |
| |
| /** |
| * Get comparator |
| * |
| * @return obtain a comparator that uses the cached hash codes |
| */ |
| public HashedSequenceComparator<S> getComparator() { |
| return new HashedSequenceComparator<>(cmp); |
| } |
| |
| /** |
| * Get A |
| * |
| * @return wrapper around A that includes cached hash codes |
| */ |
| public HashedSequence<S> getA() { |
| if (cachedA == null) |
| cachedA = wrap(baseA); |
| return cachedA; |
| } |
| |
| /** |
| * Get B |
| * |
| * @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<>(base, hashes); |
| } |
| } |