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- /*
- * Copyright (C) 2011, 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.blame;
-
- import java.io.IOException;
-
- import org.eclipse.jgit.blame.ReverseWalk.ReverseCommit;
- import org.eclipse.jgit.diff.Edit;
- import org.eclipse.jgit.diff.EditList;
- import org.eclipse.jgit.diff.RawText;
- import org.eclipse.jgit.lib.Constants;
- import org.eclipse.jgit.lib.ObjectId;
- import org.eclipse.jgit.lib.ObjectLoader;
- import org.eclipse.jgit.lib.ObjectReader;
- import org.eclipse.jgit.lib.PersonIdent;
- import org.eclipse.jgit.revwalk.RevCommit;
- import org.eclipse.jgit.revwalk.RevFlag;
- import org.eclipse.jgit.treewalk.filter.PathFilter;
-
- /**
- * A source that may have supplied some (or all) of the result file.
- * <p>
- * Candidates are kept in a queue by BlameGenerator, allowing the generator to
- * perform a parallel search down the parents of any merges that are discovered
- * during the history traversal. Each candidate retains a {@link #regionList}
- * describing sections of the result file the candidate has taken responsibility
- * for either directly or indirectly through its history. Actual blame from this
- * region list will be assigned to the candidate when its ancestor commit(s) are
- * themselves converted into Candidate objects and the ancestor's candidate uses
- * {@link #takeBlame(EditList, Candidate)} to accept responsibility for sections
- * of the result.
- */
- class Candidate {
- /** Next candidate in the candidate queue. */
- Candidate queueNext;
-
- /** Commit being considered (or blamed, depending on state). */
- RevCommit sourceCommit;
-
- /** Path of the candidate file in {@link #sourceCommit}. */
- PathFilter sourcePath;
-
- /** Unique name of the candidate blob in {@link #sourceCommit}. */
- ObjectId sourceBlob;
-
- /** Complete contents of the file in {@link #sourceCommit}. */
- RawText sourceText;
-
- /**
- * Chain of regions this candidate may be blamed for.
- * <p>
- * This list is always kept sorted by resultStart order, making it simple to
- * merge-join with the sorted EditList during blame assignment.
- */
- Region regionList;
-
- /**
- * Score assigned to the rename to this candidate.
- * <p>
- * Consider the history "A<-B<-C". If the result file S in C was renamed to
- * R in B, the rename score for this rename will be held in this field by
- * the candidate object for B. By storing the score with B, the application
- * can see what the rename score was as it makes the transition from C/S to
- * B/R. This may seem backwards since it was C that performed the rename,
- * but the application doesn't learn about path R until B.
- */
- int renameScore;
-
- Candidate(RevCommit commit, PathFilter path) {
- sourceCommit = commit;
- sourcePath = path;
- }
-
- int getParentCount() {
- return sourceCommit.getParentCount();
- }
-
- RevCommit getParent(int idx) {
- return sourceCommit.getParent(idx);
- }
-
- Candidate getNextCandidate(@SuppressWarnings("unused") int idx) {
- return null;
- }
-
- void add(RevFlag flag) {
- sourceCommit.add(flag);
- }
-
- int getTime() {
- return sourceCommit.getCommitTime();
- }
-
- PersonIdent getAuthor() {
- return sourceCommit.getAuthorIdent();
- }
-
- Candidate create(RevCommit commit, PathFilter path) {
- return new Candidate(commit, path);
- }
-
- Candidate copy(RevCommit commit) {
- Candidate r = create(commit, sourcePath);
- r.sourceBlob = sourceBlob;
- r.sourceText = sourceText;
- r.regionList = regionList;
- r.renameScore = renameScore;
- return r;
- }
-
- void loadText(ObjectReader reader) throws IOException {
- ObjectLoader ldr = reader.open(sourceBlob, Constants.OBJ_BLOB);
- sourceText = new RawText(ldr.getCachedBytes(Integer.MAX_VALUE));
- }
-
- void takeBlame(EditList editList, Candidate child) {
- blame(editList, this, child);
- }
-
- private static void blame(EditList editList, Candidate a, Candidate b) {
- Region r = b.clearRegionList();
- Region aTail = null;
- Region bTail = null;
-
- for (int eIdx = 0; eIdx < editList.size();) {
- // If there are no more regions left, neither side has any
- // more responsibility for the result. Remaining edits can
- // be safely ignored.
- if (r == null)
- return;
-
- Edit e = editList.get(eIdx);
-
- // Edit ends before the next candidate region. Skip the edit.
- if (e.getEndB() <= r.sourceStart) {
- eIdx++;
- continue;
- }
-
- // Next candidate region starts before the edit. Assign some
- // of the blame onto A, but possibly split and also on B.
- if (r.sourceStart < e.getBeginB()) {
- int d = e.getBeginB() - r.sourceStart;
- if (r.length <= d) {
- // Pass the blame for this region onto A.
- Region next = r.next;
- r.sourceStart = e.getBeginA() - d;
- aTail = add(aTail, a, r);
- r = next;
- continue;
- }
-
- // Split the region and assign some to A, some to B.
- aTail = add(aTail, a, r.splitFirst(e.getBeginA() - d, d));
- r.slideAndShrink(d);
- }
-
- // At this point e.getBeginB() <= r.sourceStart.
-
- // An empty edit on the B side isn't relevant to this split,
- // as it does not overlap any candidate region.
- if (e.getLengthB() == 0) {
- eIdx++;
- continue;
- }
-
- // If the region ends before the edit, blame on B.
- int rEnd = r.sourceStart + r.length;
- if (rEnd <= e.getEndB()) {
- Region next = r.next;
- bTail = add(bTail, b, r);
- r = next;
- if (rEnd == e.getEndB())
- eIdx++;
- continue;
- }
-
- // This region extends beyond the edit. Blame the first
- // half of the region on B, and process the rest after.
- int len = e.getEndB() - r.sourceStart;
- bTail = add(bTail, b, r.splitFirst(r.sourceStart, len));
- r.slideAndShrink(len);
- eIdx++;
- }
-
- if (r == null)
- return;
-
- // For any remaining region, pass the blame onto A after shifting
- // the source start to account for the difference between the two.
- Edit e = editList.get(editList.size() - 1);
- int endB = e.getEndB();
- int d = endB - e.getEndA();
- if (aTail == null)
- a.regionList = r;
- else
- aTail.next = r;
- do {
- if (endB <= r.sourceStart)
- r.sourceStart -= d;
- r = r.next;
- } while (r != null);
- }
-
- private static Region add(Region aTail, Candidate a, Region n) {
- // If there is no region on the list, use only this one.
- if (aTail == null) {
- a.regionList = n;
- n.next = null;
- return n;
- }
-
- // If the prior region ends exactly where the new region begins
- // in both the result and the source, combine these together into
- // one contiguous region. This occurs when intermediate commits
- // have inserted and deleted lines in the middle of a region. Try
- // to report this region as a single region to the application,
- // rather than in fragments.
- if (aTail.resultStart + aTail.length == n.resultStart
- && aTail.sourceStart + aTail.length == n.sourceStart) {
- aTail.length += n.length;
- return aTail;
- }
-
- // Append the region onto the end of the list.
- aTail.next = n;
- n.next = null;
- return n;
- }
-
- private Region clearRegionList() {
- Region r = regionList;
- regionList = null;
- return r;
- }
-
- @Override
- public String toString() {
- StringBuilder r = new StringBuilder();
- r.append("Candidate[");
- r.append(sourcePath.getPath());
- if (sourceCommit != null)
- r.append(" @ ").append(sourceCommit.abbreviate(6).name());
- if (regionList != null)
- r.append(" regions:").append(regionList);
- r.append("]");
- return r.toString();
- }
-
- /**
- * Special candidate type used for reverse blame.
- * <p>
- * Reverse blame inverts the commit history graph to follow from a commit to
- * its descendant children, rather than the normal history direction of
- * child to parent. These types require a {@link ReverseCommit} which keeps
- * children pointers, allowing reverse navigation of history.
- */
- static final class ReverseCandidate extends Candidate {
- ReverseCandidate(ReverseCommit commit, PathFilter path) {
- super(commit, path);
- }
-
- @Override
- int getParentCount() {
- return ((ReverseCommit) sourceCommit).getChildCount();
- }
-
- @Override
- RevCommit getParent(int idx) {
- return ((ReverseCommit) sourceCommit).getChild(idx);
- }
-
- @Override
- int getTime() {
- // Invert the timestamp so newer dates sort older.
- return -sourceCommit.getCommitTime();
- }
-
- @Override
- Candidate create(RevCommit commit, PathFilter path) {
- return new ReverseCandidate((ReverseCommit) commit, path);
- }
-
- @Override
- public String toString() {
- return "Reverse" + super.toString();
- }
- }
-
- /**
- * Candidate loaded from a file source, and not a commit.
- * <p>
- * The {@link Candidate#sourceCommit} field is always null on this type of
- * candidate. Instead history traversal follows the single {@link #parent}
- * field to discover the next Candidate. Often this is a normal Candidate
- * type that has a valid sourceCommit.
- */
- static final class BlobCandidate extends Candidate {
- /**
- * Next candidate to pass blame onto.
- * <p>
- * When computing the differences that this candidate introduced to the
- * file content, the parent's sourceText is used as the base.
- */
- Candidate parent;
-
- /** Author name to refer to this blob with. */
- String description;
-
- BlobCandidate(String name, PathFilter path) {
- super(null, path);
- description = name;
- }
-
- @Override
- int getParentCount() {
- return parent != null ? 1 : 0;
- }
-
- @Override
- RevCommit getParent(int idx) {
- return null;
- }
-
- @Override
- Candidate getNextCandidate(int idx) {
- return parent;
- }
-
- @Override
- void add(RevFlag flag) {
- // Do nothing, sourceCommit is null.
- }
-
- @Override
- int getTime() {
- return Integer.MAX_VALUE;
- }
-
- @Override
- PersonIdent getAuthor() {
- return new PersonIdent(description, "");
- }
- }
- }
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