001 // Protocol Buffers - Google's data interchange format 002 // Copyright 2008 Google Inc. 003 // http://code.google.com/p/protobuf/ 004 // 005 // Licensed under the Apache License, Version 2.0 (the "License"); 006 // you may not use this file except in compliance with the License. 007 // You may obtain a copy of the License at 008 // 009 // http://www.apache.org/licenses/LICENSE-2.0 010 // 011 // Unless required by applicable law or agreed to in writing, software 012 // distributed under the License is distributed on an "AS IS" BASIS, 013 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 // See the License for the specific language governing permissions and 015 // limitations under the License. 016 017 package org.fusesource.hawtbuf.proto; 018 019 /** 020 * This class is used internally by the Protocol Buffer library and generated 021 * message implementations. It is public only because those generated messages 022 * do not reside in the {@code protocol2} package. Others should not use this 023 * class directly. 024 * 025 * This class contains constants and helper functions useful for dealing with 026 * the Protocol Buffer wire format. 027 * 028 * @author kenton@google.com Kenton Varda 029 */ 030 public final class WireFormat { 031 // Do not allow instantiation. 032 private WireFormat() { 033 } 034 035 public static final int WIRETYPE_VARINT = 0; 036 public static final int WIRETYPE_FIXED64 = 1; 037 public static final int WIRETYPE_LENGTH_DELIMITED = 2; 038 public static final int WIRETYPE_START_GROUP = 3; 039 public static final int WIRETYPE_END_GROUP = 4; 040 public static final int WIRETYPE_FIXED32 = 5; 041 042 public static final int TAG_TYPE_BITS = 3; 043 public static final int TAG_TYPE_MASK = (1 << TAG_TYPE_BITS) - 1; 044 045 /** Given a tag value, determines the wire type (the lower 3 bits). */ 046 public static int getTagWireType(int tag) { 047 return tag & TAG_TYPE_MASK; 048 } 049 050 /** Given a tag value, determines the field number (the upper 29 bits). */ 051 public static int getTagFieldNumber(int tag) { 052 return tag >>> TAG_TYPE_BITS; 053 } 054 055 /** Makes a tag value given a field number and wire type. */ 056 public static int makeTag(int fieldNumber, int wireType) { 057 return (fieldNumber << TAG_TYPE_BITS) | wireType; 058 } 059 060 // Field numbers for feilds in MessageSet wire format. 061 public static final int MESSAGE_SET_ITEM = 1; 062 public static final int MESSAGE_SET_TYPE_ID = 2; 063 public static final int MESSAGE_SET_MESSAGE = 3; 064 065 // Tag numbers. 066 public static final int MESSAGE_SET_ITEM_TAG = makeTag(MESSAGE_SET_ITEM, WIRETYPE_START_GROUP); 067 public static final int MESSAGE_SET_ITEM_END_TAG = makeTag(MESSAGE_SET_ITEM, WIRETYPE_END_GROUP); 068 public static final int MESSAGE_SET_TYPE_ID_TAG = makeTag(MESSAGE_SET_TYPE_ID, WIRETYPE_VARINT); 069 public static final int MESSAGE_SET_MESSAGE_TAG = makeTag(MESSAGE_SET_MESSAGE, WIRETYPE_LENGTH_DELIMITED); 070 }