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// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.
// http://code.google.com/p/protobuf/
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
using System.Reflection;
using Google.ProtocolBuffers.Descriptors;
using System.Collections.Generic;
using Google.ProtocolBuffers.Collections;
namespace Google.ProtocolBuffers {
/// <summary>
/// This class is used internally by the Protocol Buffer Library and generated
/// message implementations. It is public only for the sake of those generated
/// messages. Others should not use this class directly.
/// <para>
/// This class contains constants and helper functions useful for dealing with
/// the Protocol Buffer wire format.
/// </para>
/// </summary>
public class WireFormat {
public enum WireType : uint {
Varint = 0,
Fixed64 = 1,
LengthDelimited = 2,
StartGroup = 3,
EndGroup = 4,
Fixed32 = 5
}
internal class MessageSetField {
internal const int Item = 1;
internal const int TypeID = 2;
internal const int Message = 3;
}
internal class MessageSetTag {
internal static readonly uint ItemStart = MakeTag(MessageSetField.Item, WireType.StartGroup);
internal static readonly uint ItemEnd = MakeTag(MessageSetField.Item, WireType.EndGroup);
internal static readonly uint TypeID = MakeTag(MessageSetField.TypeID, WireType.Varint);
internal static readonly uint Message = MakeTag(MessageSetField.Message, WireType.LengthDelimited);
}
private const int TagTypeBits = 3;
private const uint TagTypeMask = (1 << TagTypeBits) - 1;
/// <summary>
/// Given a tag value, determines the wire type (lower 3 bits).
/// </summary>
public static WireType GetTagWireType(uint tag) {
return (WireType) (tag & TagTypeMask);
}
/// <summary>
/// Given a tag value, determines the field number (the upper 29 bits).
/// </summary>
public static int GetTagFieldNumber(uint tag) {
return (int) tag >> TagTypeBits;
}
/// <summary>
/// Makes a tag value given a field number and wire type.
/// TODO(jonskeet): Should we just have a Tag structure?
/// </summary>
public static uint MakeTag(int fieldNumber, WireType wireType) {
return (uint) (fieldNumber << TagTypeBits) | (uint) wireType;
}
/// <summary>
/// Immutable mapping from field type to wire type. Built using the attributes on
/// FieldType values.
/// </summary>
public static readonly IDictionary<FieldType, WireType> FieldTypeToWireFormatMap = MapFieldTypes();
private static IDictionary<FieldType, WireType> MapFieldTypes() {
var map = new Dictionary<FieldType, WireType>();
foreach (FieldInfo field in typeof(FieldType).GetFields(BindingFlags.Static | BindingFlags.Public)) {
FieldType fieldType = (FieldType) field.GetValue(null);
FieldMappingAttribute mapping = (FieldMappingAttribute)field.GetCustomAttributes(typeof(FieldMappingAttribute), false)[0];
map[fieldType] = mapping.WireType;
}
return Dictionaries.AsReadOnly(map);
}
}
}
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