CommitBuilder.java

/*
 * Copyright (C) 2007, Dave Watson <dwatson@mimvista.com>
 * Copyright (C) 2006, 2007, Robin Rosenberg <robin.rosenberg@dewire.com>
 * Copyright (C) 2006, 2020, Shawn O. Pearce <spearce@spearce.org> 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.lib;

import static java.nio.charset.StandardCharsets.UTF_8;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.List;

import org.eclipse.jgit.util.References;

/**
 * Mutable builder to construct a commit recording the state of a project.
 *
 * Applications should use this object when they need to manually construct a
 * commit and want precise control over its fields. For a higher level interface
 * see {@link org.eclipse.jgit.api.CommitCommand}.
 *
 * To read a commit object, construct a {@link org.eclipse.jgit.revwalk.RevWalk}
 * and obtain a {@link org.eclipse.jgit.revwalk.RevCommit} instance by calling
 * {@link org.eclipse.jgit.revwalk.RevWalk#parseCommit(AnyObjectId)}.
 */
public class CommitBuilder extends ObjectBuilder {
    private static final ObjectId[] EMPTY_OBJECTID_LIST = new ObjectId[0];

    private static final byte[] htree = Constants.encodeASCII("tree"); //$NON-NLS-1$

    private static final byte[] hparent = Constants.encodeASCII("parent"); //$NON-NLS-1$

    private static final byte[] hauthor = Constants.encodeASCII("author"); //$NON-NLS-1$

    private static final byte[] hcommitter = Constants.encodeASCII("committer"); //$NON-NLS-1$

    private static final byte[] hgpgsig = Constants.encodeASCII("gpgsig"); //$NON-NLS-1$

    private ObjectId treeId;

    private ObjectId[] parentIds;

    private PersonIdent committer;

    /**
     * Initialize an empty commit.
     */
    public CommitBuilder() {
        parentIds = EMPTY_OBJECTID_LIST;
    }

    /**
     * Get id of the root tree listing this commit's snapshot.
     *
     * @return id of the root tree listing this commit's snapshot.
     */
    public ObjectId getTreeId() {
        return treeId;
    }

    /**
     * Set the tree id for this commit object.
     *
     * @param id
     *            the tree identity.
     */
    public void setTreeId(AnyObjectId id) {
        treeId = id.copy();
    }

    /**
     * Get the author of this commit (who wrote it).
     *
     * @return the author of this commit (who wrote it).
     */
    @Override
    public PersonIdent getAuthor() {
        return super.getAuthor();
    }

    /**
     * Set the author (name, email address, and date) of who wrote the commit.
     *
     * @param newAuthor
     *            the new author. Should not be null.
     */
    @Override
    public void setAuthor(PersonIdent newAuthor) {
        super.setAuthor(newAuthor);
    }

    /**
     * Get the committer and commit time for this object.
     *
     * @return the committer and commit time for this object.
     */
    public PersonIdent getCommitter() {
        return committer;
    }

    /**
     * Set the committer and commit time for this object.
     *
     * @param newCommitter
     *            the committer information. Should not be null.
     */
    public void setCommitter(PersonIdent newCommitter) {
        committer = newCommitter;
    }

    /**
     * Get the ancestors of this commit.
     *
     * @return the ancestors of this commit. Never null.
     */
    public ObjectId[] getParentIds() {
        return parentIds;
    }

    /**
     * Set the parent of this commit.
     *
     * @param newParent
     *            the single parent for the commit.
     */
    public void setParentId(AnyObjectId newParent) {
        parentIds = new ObjectId[] { newParent.copy() };
    }

    /**
     * Set the parents of this commit.
     *
     * @param parent1
     *            the first parent of this commit. Typically this is the current
     *            value of the {@code HEAD} reference and is thus the current
     *            branch's position in history.
     * @param parent2
     *            the second parent of this merge commit. Usually this is the
     *            branch being merged into the current branch.
     */
    public void setParentIds(AnyObjectId parent1, AnyObjectId parent2) {
        parentIds = new ObjectId[] { parent1.copy(), parent2.copy() };
    }

    /**
     * Set the parents of this commit.
     *
     * @param newParents
     *            the entire list of parents for this commit.
     */
    public void setParentIds(ObjectId... newParents) {
        parentIds = new ObjectId[newParents.length];
        for (int i = 0; i < newParents.length; i++)
            parentIds[i] = newParents[i].copy();
    }

    /**
     * Set the parents of this commit.
     *
     * @param newParents
     *            the entire list of parents for this commit.
     */
    public void setParentIds(List<? extends AnyObjectId> newParents) {
        parentIds = new ObjectId[newParents.size()];
        for (int i = 0; i < newParents.size(); i++)
            parentIds[i] = newParents.get(i).copy();
    }

    /**
     * Add a parent onto the end of the parent list.
     *
     * @param additionalParent
     *            new parent to add onto the end of the current parent list.
     */
    public void addParentId(AnyObjectId additionalParent) {
        if (parentIds.length == 0) {
            setParentId(additionalParent);
        } else {
            ObjectId[] newParents = new ObjectId[parentIds.length + 1];
            System.arraycopy(parentIds, 0, newParents, 0, parentIds.length);
            newParents[parentIds.length] = additionalParent.copy();
            parentIds = newParents;
        }
    }

    /**
     * Set the encoding for the commit information.
     *
     * @param encodingName
     *            the encoding name. See
     *            {@link java.nio.charset.Charset#forName(String)}.
     * @deprecated use {@link #setEncoding(Charset)} instead.
     */
    @Deprecated
    public void setEncoding(String encodingName) {
        setEncoding(Charset.forName(encodingName));
    }

    @Override
    public byte[] build() throws UnsupportedEncodingException {
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        OutputStreamWriter w = new OutputStreamWriter(os, getEncoding());
        try {
            os.write(htree);
            os.write(' ');
            getTreeId().copyTo(os);
            os.write('\n');

            for (ObjectId p : getParentIds()) {
                os.write(hparent);
                os.write(' ');
                p.copyTo(os);
                os.write('\n');
            }

            os.write(hauthor);
            os.write(' ');
            w.write(getAuthor().toExternalString());
            w.flush();
            os.write('\n');

            os.write(hcommitter);
            os.write(' ');
            w.write(getCommitter().toExternalString());
            w.flush();
            os.write('\n');

            GpgSignature signature = getGpgSignature();
            if (signature != null) {
                os.write(hgpgsig);
                os.write(' ');
                writeMultiLineHeader(signature.toExternalString(), os,
                        true);
                os.write('\n');
            }

            writeEncoding(getEncoding(), os);

            os.write('\n');

            if (getMessage() != null) {
                w.write(getMessage());
                w.flush();
            }
        } catch (IOException err) {
            // This should never occur, the only way to get it above is
            // for the ByteArrayOutputStream to throw, but it doesn't.
            //
            throw new RuntimeException(err);
        }
        return os.toByteArray();
    }

    /**
     * Format this builder's state as a commit object.
     *
     * @return this object in the canonical commit format, suitable for storage
     *         in a repository.
     * @throws java.io.UnsupportedEncodingException
     *             the encoding specified by {@link #getEncoding()} is not
     *             supported by this Java runtime.
     */
    public byte[] toByteArray() throws UnsupportedEncodingException {
        return build();
    }

    /** {@inheritDoc} */
    @SuppressWarnings("nls")
    @Override
    public String toString() {
        StringBuilder r = new StringBuilder();
        r.append("Commit");
        r.append("={\n");

        r.append("tree ");
        r.append(treeId != null ? treeId.name() : "NOT_SET");
        r.append("\n");

        for (ObjectId p : parentIds) {
            r.append("parent ");
            r.append(p.name());
            r.append("\n");
        }

        r.append("author ");
        r.append(getAuthor() != null ? getAuthor().toString() : "NOT_SET");
        r.append("\n");

        r.append("committer ");
        r.append(committer != null ? committer.toString() : "NOT_SET");
        r.append("\n");

        r.append("gpgSignature ");
        GpgSignature signature = getGpgSignature();
        r.append(signature != null ? signature.toString()
                : "NOT_SET");
        r.append("\n");

        Charset encoding = getEncoding();
        if (!References.isSameObject(encoding, UTF_8)) {
            r.append("encoding ");
            r.append(encoding.name());
            r.append("\n");
        }

        r.append("\n");
        r.append(getMessage() != null ? getMessage() : "");
        r.append("}");
        return r.toString();
    }
}