1// Protocol Buffers - Google's data interchange format
2// Copyright 2008 Google Inc.  All rights reserved.
3// http://code.google.com/p/protobuf/
4//
5// Redistribution and use in source and binary forms, with or without
6// modification, are permitted provided that the following conditions are
7// met:
8//
9//     * Redistributions of source code must retain the above copyright
10// notice, this list of conditions and the following disclaimer.
11//     * Redistributions in binary form must reproduce the above
12// copyright notice, this list of conditions and the following disclaimer
13// in the documentation and/or other materials provided with the
14// distribution.
15//     * Neither the name of Google Inc. nor the names of its
16// contributors may be used to endorse or promote products derived from
17// this software without specific prior written permission.
18//
19// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30
31package com.google.protobuf;
32
33/**
34 * This class is used internally by the Protocol Buffer library and generated
35 * message implementations.  It is public only because those generated messages
36 * do not reside in the {@code protobuf} package.  Others should not use this
37 * class directly.
38 *
39 * This class contains constants and helper functions useful for dealing with
40 * the Protocol Buffer wire format.
41 *
42 * @author kenton@google.com Kenton Varda
43 */
44public final class WireFormat {
45  // Do not allow instantiation.
46  private WireFormat() {}
47
48  static final int WIRETYPE_VARINT           = 0;
49  static final int WIRETYPE_FIXED64          = 1;
50  static final int WIRETYPE_LENGTH_DELIMITED = 2;
51  static final int WIRETYPE_START_GROUP      = 3;
52  static final int WIRETYPE_END_GROUP        = 4;
53  static final int WIRETYPE_FIXED32          = 5;
54
55  static final int TAG_TYPE_BITS = 3;
56  static final int TAG_TYPE_MASK = (1 << TAG_TYPE_BITS) - 1;
57
58  /** Given a tag value, determines the wire type (the lower 3 bits). */
59  static int getTagWireType(final int tag) {
60    return tag & TAG_TYPE_MASK;
61  }
62
63  /** Given a tag value, determines the field number (the upper 29 bits). */
64  public static int getTagFieldNumber(final int tag) {
65    return tag >>> TAG_TYPE_BITS;
66  }
67
68  /** Makes a tag value given a field number and wire type. */
69  static int makeTag(final int fieldNumber, final int wireType) {
70    return (fieldNumber << TAG_TYPE_BITS) | wireType;
71  }
72
73  /**
74   * Lite equivalent to {@link Descriptors.FieldDescriptor.JavaType}.  This is
75   * only here to support the lite runtime and should not be used by users.
76   */
77  public enum JavaType {
78    INT(0),
79    LONG(0L),
80    FLOAT(0F),
81    DOUBLE(0D),
82    BOOLEAN(false),
83    STRING(""),
84    BYTE_STRING(ByteString.EMPTY),
85    ENUM(null),
86    MESSAGE(null);
87
88    JavaType(final Object defaultDefault) {
89      this.defaultDefault = defaultDefault;
90    }
91
92    /**
93     * The default default value for fields of this type, if it's a primitive
94     * type.
95     */
96    Object getDefaultDefault() {
97      return defaultDefault;
98    }
99
100    private final Object defaultDefault;
101  }
102
103  /**
104   * Lite equivalent to {@link Descriptors.FieldDescriptor.Type}.  This is
105   * only here to support the lite runtime and should not be used by users.
106   */
107  public enum FieldType {
108    DOUBLE  (JavaType.DOUBLE     , WIRETYPE_FIXED64         ),
109    FLOAT   (JavaType.FLOAT      , WIRETYPE_FIXED32         ),
110    INT64   (JavaType.LONG       , WIRETYPE_VARINT          ),
111    UINT64  (JavaType.LONG       , WIRETYPE_VARINT          ),
112    INT32   (JavaType.INT        , WIRETYPE_VARINT          ),
113    FIXED64 (JavaType.LONG       , WIRETYPE_FIXED64         ),
114    FIXED32 (JavaType.INT        , WIRETYPE_FIXED32         ),
115    BOOL    (JavaType.BOOLEAN    , WIRETYPE_VARINT          ),
116    STRING  (JavaType.STRING     , WIRETYPE_LENGTH_DELIMITED) {
117      public boolean isPackable() { return false; }
118    },
119    GROUP   (JavaType.MESSAGE    , WIRETYPE_START_GROUP     ) {
120      public boolean isPackable() { return false; }
121    },
122    MESSAGE (JavaType.MESSAGE    , WIRETYPE_LENGTH_DELIMITED) {
123      public boolean isPackable() { return false; }
124    },
125    BYTES   (JavaType.BYTE_STRING, WIRETYPE_LENGTH_DELIMITED) {
126      public boolean isPackable() { return false; }
127    },
128    UINT32  (JavaType.INT        , WIRETYPE_VARINT          ),
129    ENUM    (JavaType.ENUM       , WIRETYPE_VARINT          ),
130    SFIXED32(JavaType.INT        , WIRETYPE_FIXED32         ),
131    SFIXED64(JavaType.LONG       , WIRETYPE_FIXED64         ),
132    SINT32  (JavaType.INT        , WIRETYPE_VARINT          ),
133    SINT64  (JavaType.LONG       , WIRETYPE_VARINT          );
134
135    FieldType(final JavaType javaType, final int wireType) {
136      this.javaType = javaType;
137      this.wireType = wireType;
138    }
139
140    private final JavaType javaType;
141    private final int wireType;
142
143    public JavaType getJavaType() { return javaType; }
144    public int getWireType() { return wireType; }
145
146    public boolean isPackable() { return true; }
147  }
148
149  // Field numbers for feilds in MessageSet wire format.
150  static final int MESSAGE_SET_ITEM    = 1;
151  static final int MESSAGE_SET_TYPE_ID = 2;
152  static final int MESSAGE_SET_MESSAGE = 3;
153
154  // Tag numbers.
155  static final int MESSAGE_SET_ITEM_TAG =
156    makeTag(MESSAGE_SET_ITEM, WIRETYPE_START_GROUP);
157  static final int MESSAGE_SET_ITEM_END_TAG =
158    makeTag(MESSAGE_SET_ITEM, WIRETYPE_END_GROUP);
159  static final int MESSAGE_SET_TYPE_ID_TAG =
160    makeTag(MESSAGE_SET_TYPE_ID, WIRETYPE_VARINT);
161  static final int MESSAGE_SET_MESSAGE_TAG =
162    makeTag(MESSAGE_SET_MESSAGE, WIRETYPE_LENGTH_DELIMITED);
163}
164