| /* |
| * 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 a {@link org.eclipse.jgit.diff.Sequence} to have a narrower range of |
| * elements. |
| * <p> |
| * This sequence acts as a proxy for the real sequence, translating element |
| * indexes on the fly by adding {@code begin} to them. Sequences of this type |
| * must be used with a {@link org.eclipse.jgit.diff.SubsequenceComparator}. |
| * |
| * @param <S> |
| * the base sequence type. |
| */ |
| public final class Subsequence<S extends Sequence> extends Sequence { |
| /** |
| * Construct a subsequence around the A region/base sequence. |
| * |
| * @param a |
| * the A sequence. |
| * @param region |
| * the region of {@code a} to create a subsequence around. |
| * @return subsequence of {@code base} as described by A in {@code region}. |
| */ |
| public static <S extends Sequence> Subsequence<S> a(S a, Edit region) { |
| return new Subsequence<>(a, region.beginA, region.endA); |
| } |
| |
| /** |
| * Construct a subsequence around the B region/base sequence. |
| * |
| * @param b |
| * the B sequence. |
| * @param region |
| * the region of {@code b} to create a subsequence around. |
| * @return subsequence of {@code base} as described by B in {@code region}. |
| */ |
| public static <S extends Sequence> Subsequence<S> b(S b, Edit region) { |
| return new Subsequence<>(b, region.beginB, region.endB); |
| } |
| |
| /** |
| * Adjust the Edit to reflect positions in the base sequence. |
| * |
| * @param e |
| * edit to adjust in-place. Prior to invocation the indexes are |
| * in terms of the two subsequences; after invocation the indexes |
| * are in terms of the base sequences. |
| * @param a |
| * the A sequence. |
| * @param b |
| * the B sequence. |
| */ |
| public static <S extends Sequence> void toBase(Edit e, Subsequence<S> a, |
| Subsequence<S> b) { |
| e.beginA += a.begin; |
| e.endA += a.begin; |
| |
| e.beginB += b.begin; |
| e.endB += b.begin; |
| } |
| |
| /** |
| * Adjust the Edits to reflect positions in the base sequence. |
| * |
| * @param edits |
| * edits to adjust in-place. Prior to invocation the indexes are |
| * in terms of the two subsequences; after invocation the indexes |
| * are in terms of the base sequences. |
| * @param a |
| * the A sequence. |
| * @param b |
| * the B sequence. |
| * @return always {@code edits} (as the list was updated in-place). |
| */ |
| public static <S extends Sequence> EditList toBase(EditList edits, |
| Subsequence<S> a, Subsequence<S> b) { |
| for (Edit e : edits) |
| toBase(e, a, b); |
| return edits; |
| } |
| |
| final S base; |
| |
| final int begin; |
| |
| private final int size; |
| |
| /** |
| * Construct a subset of another sequence. |
| * |
| * The size of the subsequence will be {@code end - begin}. |
| * |
| * @param base |
| * the real sequence. |
| * @param begin |
| * First element index of {@code base} that will be part of this |
| * new subsequence. The element at {@code begin} will be this |
| * sequence's element 0. |
| * @param end |
| * One past the last element index of {@code base} that will be |
| * part of this new subsequence. |
| */ |
| public Subsequence(S base, int begin, int end) { |
| this.base = base; |
| this.begin = begin; |
| this.size = end - begin; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public int size() { |
| return size; |
| } |
| } |