DiffCommand.java

/*
 * Copyright (C) 2011, Tomasz Zarna <Tomasz.Zarna@pl.ibm.com> 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.api;

import static org.eclipse.jgit.lib.Constants.HEAD;

import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.List;

import org.eclipse.jgit.api.errors.GitAPIException;
import org.eclipse.jgit.api.errors.JGitInternalException;
import org.eclipse.jgit.api.errors.NoHeadException;
import org.eclipse.jgit.diff.DiffEntry;
import org.eclipse.jgit.diff.DiffFormatter;
import org.eclipse.jgit.dircache.DirCacheIterator;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.lib.NullProgressMonitor;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectReader;
import org.eclipse.jgit.lib.ProgressMonitor;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.treewalk.AbstractTreeIterator;
import org.eclipse.jgit.treewalk.CanonicalTreeParser;
import org.eclipse.jgit.treewalk.FileTreeIterator;
import org.eclipse.jgit.treewalk.filter.TreeFilter;
import org.eclipse.jgit.util.io.NullOutputStream;

/**
 * Show changes between commits, commit and working tree, etc.
 *
 * @see <a href="http://www.kernel.org/pub/software/scm/git/docs/git-diff.html"
 *      >Git documentation about diff</a>
 */
public class DiffCommand extends GitCommand<List<DiffEntry>> {
    private AbstractTreeIterator oldTree;

    private AbstractTreeIterator newTree;

    private boolean cached;

    private TreeFilter pathFilter = TreeFilter.ALL;

    private boolean showNameAndStatusOnly;

    private OutputStream out;

    private int contextLines = -1;

    private String sourcePrefix;

    private String destinationPrefix;

    private ProgressMonitor monitor = NullProgressMonitor.INSTANCE;

    /**
     * Constructor for DiffCommand
     *
     * @param repo
     *            a {@link org.eclipse.jgit.lib.Repository} object.
     */
    protected DiffCommand(Repository repo) {
        super(repo);
    }

    private DiffFormatter getDiffFormatter() {
        return out != null && !showNameAndStatusOnly
                ? new DiffFormatter(new BufferedOutputStream(out))
                : new DiffFormatter(NullOutputStream.INSTANCE);
    }

    /**
     * {@inheritDoc}
     * <p>
     * Executes the {@code Diff} command with all the options and parameters
     * collected by the setter methods (e.g. {@link #setCached(boolean)} of this
     * class. Each instance of this class should only be used for one invocation
     * of the command. Don't call this method twice on an instance.
     */
    @Override
    public List<DiffEntry> call() throws GitAPIException {
        try (DiffFormatter diffFmt = getDiffFormatter()) {
            diffFmt.setRepository(repo);
            diffFmt.setProgressMonitor(monitor);
            if (cached) {
                if (oldTree == null) {
                    ObjectId head = repo.resolve(HEAD + "^{tree}"); //$NON-NLS-1$
                    if (head == null)
                        throw new NoHeadException(JGitText.get().cannotReadTree);
                    CanonicalTreeParser p = new CanonicalTreeParser();
                    try (ObjectReader reader = repo.newObjectReader()) {
                        p.reset(reader, head);
                    }
                    oldTree = p;
                }
                newTree = new DirCacheIterator(repo.readDirCache());
            } else {
                if (oldTree == null) {
                    oldTree = new DirCacheIterator(repo.readDirCache());
                }
                if (newTree == null) {
                    newTree = new FileTreeIterator(repo);
                }
            }

            diffFmt.setPathFilter(pathFilter);

            List<DiffEntry> result = diffFmt.scan(oldTree, newTree);
            if (showNameAndStatusOnly) {
                return result;
            }
            if (contextLines >= 0) {
                diffFmt.setContext(contextLines);
            }
            if (destinationPrefix != null) {
                diffFmt.setNewPrefix(destinationPrefix);
            }
            if (sourcePrefix != null) {
                diffFmt.setOldPrefix(sourcePrefix);
            }
            diffFmt.format(result);
            diffFmt.flush();
            return result;
        } catch (IOException e) {
            throw new JGitInternalException(e.getMessage(), e);
        }
    }

    /**
     * Whether to view the changes staged for the next commit
     *
     * @param cached
     *            whether to view the changes staged for the next commit
     * @return this instance
     */
    public DiffCommand setCached(boolean cached) {
        this.cached = cached;
        return this;
    }

    /**
     * Set path filter
     *
     * @param pathFilter
     *            parameter, used to limit the diff to the named path
     * @return this instance
     */
    public DiffCommand setPathFilter(TreeFilter pathFilter) {
        this.pathFilter = pathFilter;
        return this;
    }

    /**
     * Set old tree
     *
     * @param oldTree
     *            the previous state
     * @return this instance
     */
    public DiffCommand setOldTree(AbstractTreeIterator oldTree) {
        this.oldTree = oldTree;
        return this;
    }

    /**
     * Set new tree
     *
     * @param newTree
     *            the updated state
     * @return this instance
     */
    public DiffCommand setNewTree(AbstractTreeIterator newTree) {
        this.newTree = newTree;
        return this;
    }

    /**
     * Set whether to return only names and status of changed files
     *
     * @param showNameAndStatusOnly
     *            whether to return only names and status of changed files
     * @return this instance
     */
    public DiffCommand setShowNameAndStatusOnly(boolean showNameAndStatusOnly) {
        this.showNameAndStatusOnly = showNameAndStatusOnly;
        return this;
    }

    /**
     * Set output stream
     *
     * @param out
     *            the stream to write line data
     * @return this instance
     */
    public DiffCommand setOutputStream(OutputStream out) {
        this.out = out;
        return this;
    }

    /**
     * Set number of context lines instead of the usual three.
     *
     * @param contextLines
     *            the number of context lines
     * @return this instance
     */
    public DiffCommand setContextLines(int contextLines) {
        this.contextLines = contextLines;
        return this;
    }

    /**
     * Set the given source prefix instead of "a/".
     *
     * @param sourcePrefix
     *            the prefix
     * @return this instance
     */
    public DiffCommand setSourcePrefix(String sourcePrefix) {
        this.sourcePrefix = sourcePrefix;
        return this;
    }

    /**
     * Set the given destination prefix instead of "b/".
     *
     * @param destinationPrefix
     *            the prefix
     * @return this instance
     */
    public DiffCommand setDestinationPrefix(String destinationPrefix) {
        this.destinationPrefix = destinationPrefix;
        return this;
    }

    /**
     * The progress monitor associated with the diff operation. By default, this
     * is set to <code>NullProgressMonitor</code>
     *
     * @see NullProgressMonitor
     * @param monitor
     *            a progress monitor
     * @return this instance
     */
    public DiffCommand setProgressMonitor(ProgressMonitor monitor) {
        if (monitor == null) {
            monitor = NullProgressMonitor.INSTANCE;
        }
        this.monitor = monitor;
        return this;
    }
}