com.google.gitiles.DiffServlet.java Source code

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Here is the source code for com.google.gitiles.DiffServlet.java

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// Copyright 2012 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.gitiles;

import static com.google.common.base.Preconditions.checkNotNull;
import static javax.servlet.http.HttpServletResponse.SC_NOT_FOUND;

import com.google.common.base.Charsets;

import org.eclipse.jgit.diff.DiffFormatter;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.http.server.ServletUtils;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.treewalk.AbstractTreeIterator;
import org.eclipse.jgit.treewalk.CanonicalTreeParser;
import org.eclipse.jgit.treewalk.EmptyTreeIterator;
import org.eclipse.jgit.treewalk.filter.PathFilter;

import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/** Serves an HTML page with all the diffs for a commit. */
public class DiffServlet extends BaseServlet {
    private static final String PLACEHOLDER = "id=\"DIFF_OUTPUT_BLOCK\"";

    private final Linkifier linkifier;

    public DiffServlet(Renderer renderer, Linkifier linkifier) {
        super(renderer);
        this.linkifier = checkNotNull(linkifier, "linkifier");
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException {
        GitilesView view = ViewFilter.getView(req);
        Repository repo = ServletUtils.getRepository(req);

        RevWalk walk = new RevWalk(repo);
        try {
            boolean showCommit;
            AbstractTreeIterator oldTree;
            AbstractTreeIterator newTree;
            try {
                // If we are viewing the diff between a commit and one of its parents,
                // include the commit detail in the rendered page.
                showCommit = isParentOf(walk, view.getOldRevision(), view.getRevision());
                oldTree = getTreeIterator(walk, view.getOldRevision().getId());
                newTree = getTreeIterator(walk, view.getRevision().getId());
            } catch (MissingObjectException e) {
                res.setStatus(SC_NOT_FOUND);
                return;
            } catch (IncorrectObjectTypeException e) {
                res.setStatus(SC_NOT_FOUND);
                return;
            }

            Map<String, Object> data = getData(req);
            data.put("title", "Diff - " + view.getRevisionRange());
            if (showCommit) {
                data.put("commit", new CommitSoyData(linkifier, req, repo, walk, view)
                        .toSoyData(walk.parseCommit(view.getRevision().getId())));
            }
            if (!data.containsKey("repositoryName") && (view.getRepositoryName() != null)) {
                data.put("repositoryName", view.getRepositoryName());
            }
            if (!data.containsKey("breadcrumbs")) {
                data.put("breadcrumbs", view.getBreadcrumbs());
            }

            String[] html = renderAndSplit(data);
            res.setStatus(HttpServletResponse.SC_OK);
            res.setContentType(FormatType.HTML.getMimeType());
            res.setCharacterEncoding(Charsets.UTF_8.name());
            setCacheHeaders(req, res);

            OutputStream out = res.getOutputStream();
            try {
                out.write(html[0].getBytes(Charsets.UTF_8));
                formatHtmlDiff(out, repo, walk, oldTree, newTree, view.getTreePath());
                out.write(html[1].getBytes(Charsets.UTF_8));
            } finally {
                out.close();
            }
        } finally {
            walk.release();
        }
    }

    private static boolean isParentOf(RevWalk walk, Revision oldRevision, Revision newRevision)
            throws MissingObjectException, IncorrectObjectTypeException, IOException {
        RevCommit newCommit = walk.parseCommit(newRevision.getId());
        if (newCommit.getParentCount() > 0) {
            return Arrays.asList(newCommit.getParents()).contains(oldRevision.getId());
        } else {
            return oldRevision == Revision.NULL;
        }
    }

    private String[] renderAndSplit(Map<String, Object> data) {
        String html = renderer.newRenderer("gitiles.diffDetail").setData(data).render();
        int id = html.indexOf(PLACEHOLDER);
        if (id < 0) {
            throw new IllegalStateException("Template must contain " + PLACEHOLDER);
        }

        int lt = html.lastIndexOf('<', id);
        int gt = html.indexOf('>', id + PLACEHOLDER.length());
        return new String[] { html.substring(0, lt), html.substring(gt + 1) };
    }

    private void formatHtmlDiff(OutputStream out, Repository repo, RevWalk walk, AbstractTreeIterator oldTree,
            AbstractTreeIterator newTree, String path) throws IOException {
        DiffFormatter diff = new HtmlDiffFormatter(renderer, out);
        try {
            if (!path.equals("")) {
                diff.setPathFilter(PathFilter.create(path));
            }
            diff.setRepository(repo);
            diff.setDetectRenames(true);
            diff.format(oldTree, newTree);
        } finally {
            diff.release();
        }
    }

    private static AbstractTreeIterator getTreeIterator(RevWalk walk, ObjectId id) throws IOException {
        if (!id.equals(ObjectId.zeroId())) {
            CanonicalTreeParser p = new CanonicalTreeParser();
            p.reset(walk.getObjectReader(), walk.parseTree(id));
            return p;
        } else {
            return new EmptyTreeIterator();
        }
    }
}