| /* |
| * Copyright (C) 2009, The Android Open Source Project |
| * Copyright (C) 2009, Shawn O. Pearce <spearce@spearce.org> |
| * Copyright (C) 2018, David Pursehouse <david.pursehouse@gmail.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.lib; |
| |
| import static org.eclipse.jgit.lib.Constants.OBJECT_ID_LENGTH; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.io.OutputStream; |
| |
| import org.eclipse.jgit.annotations.NonNull; |
| import org.eclipse.jgit.annotations.Nullable; |
| import org.eclipse.jgit.util.IO; |
| |
| /** |
| * Helper to serialize {@link ObjectId} instances. {@link ObjectId} is already |
| * serializable, but this class provides methods to handle null and non-null |
| * instances. |
| * |
| * @since 4.11 |
| */ |
| public class ObjectIdSerializer { |
| /* |
| * Marker to indicate a null ObjectId instance. |
| */ |
| private static final byte NULL_MARKER = 0; |
| |
| /* |
| * Marker to indicate a non-null ObjectId instance. |
| */ |
| private static final byte NON_NULL_MARKER = 1; |
| |
| /** |
| * Write a possibly null {@link ObjectId} to the stream, using markers to |
| * differentiate null and non-null instances. |
| * |
| * <p> |
| * If the id is non-null, writes a {@link #NON_NULL_MARKER} followed by the |
| * id's words. If it is null, writes a {@link #NULL_MARKER} and nothing |
| * else. |
| * |
| * @param out |
| * the output stream |
| * @param id |
| * the object id to serialize; may be null |
| * @throws IOException |
| * the stream writing failed |
| */ |
| public static void write(OutputStream out, @Nullable AnyObjectId id) |
| throws IOException { |
| if (id != null) { |
| out.write(NON_NULL_MARKER); |
| writeWithoutMarker(out, id); |
| } else { |
| out.write(NULL_MARKER); |
| } |
| } |
| |
| /** |
| * Write a non-null {@link ObjectId} to the stream. |
| * |
| * @param out |
| * the output stream |
| * @param id |
| * the object id to serialize; never null |
| * @throws IOException |
| * the stream writing failed |
| * @since 4.11 |
| */ |
| public static void writeWithoutMarker(OutputStream out, @NonNull AnyObjectId id) |
| throws IOException { |
| id.copyRawTo(out); |
| } |
| |
| /** |
| * Read a possibly null {@link ObjectId} from the stream. |
| * |
| * Reads the first byte of the stream, which is expected to be either |
| * {@link #NON_NULL_MARKER} or {@link #NULL_MARKER}. |
| * |
| * @param in |
| * the input stream |
| * @return the object id, or null |
| * @throws IOException |
| * there was an error reading the stream |
| */ |
| @Nullable |
| public static ObjectId read(InputStream in) throws IOException { |
| byte marker = (byte) in.read(); |
| switch (marker) { |
| case NULL_MARKER: |
| return null; |
| case NON_NULL_MARKER: |
| return readWithoutMarker(in); |
| default: |
| throw new IOException("Invalid flag before ObjectId: " + marker); //$NON-NLS-1$ |
| } |
| } |
| |
| /** |
| * Read a non-null {@link ObjectId} from the stream. |
| * |
| * @param in |
| * the input stream |
| * @return the object id; never null |
| * @throws IOException |
| * there was an error reading the stream |
| * @since 4.11 |
| */ |
| @NonNull |
| public static ObjectId readWithoutMarker(InputStream in) throws IOException { |
| final byte[] b = new byte[OBJECT_ID_LENGTH]; |
| IO.readFully(in, b, 0, OBJECT_ID_LENGTH); |
| return ObjectId.fromRaw(b); |
| } |
| |
| private ObjectIdSerializer() { |
| } |
| } |