1 #region Copyright notice and license 2 // Protocol Buffers - Google's data interchange format 3 // Copyright 2008 Google Inc. All rights reserved. 4 // 5 // Use of this source code is governed by a BSD-style 6 // license that can be found in the LICENSE file or at 7 // https://developers.google.com/open-source/licenses/bsd 8 #endregion 9 10 using System; 11 12 namespace Google.Protobuf 13 { 14 /// <summary> 15 /// Represents a non-generic extension definition. This API is experimental and subject to change. 16 /// </summary> 17 public abstract class Extension 18 { 19 internal abstract Type TargetType { get; } 20 21 /// <summary> 22 /// Internal use. Creates a new extension with the specified field number. 23 /// </summary> Extension(int fieldNumber)24 protected Extension(int fieldNumber) 25 { 26 FieldNumber = fieldNumber; 27 } 28 CreateValue()29 internal abstract IExtensionValue CreateValue(); 30 31 /// <summary> 32 /// Gets the field number of this extension 33 /// </summary> 34 public int FieldNumber { get; } 35 36 internal abstract bool IsRepeated { get; } 37 } 38 39 /// <summary> 40 /// Represents a type-safe extension identifier used for getting and setting single extension values in <see cref="IExtendableMessage{T}"/> instances. 41 /// This API is experimental and subject to change. 42 /// </summary> 43 /// <typeparam name="TTarget">The message type this field applies to</typeparam> 44 /// <typeparam name="TValue">The field value type of this extension</typeparam> 45 public sealed class Extension<TTarget, TValue> : Extension where TTarget : IExtendableMessage<TTarget> 46 { 47 private readonly FieldCodec<TValue> codec; 48 49 /// <summary> 50 /// Creates a new extension identifier with the specified field number and codec 51 /// </summary> Extension(int fieldNumber, FieldCodec<TValue> codec)52 public Extension(int fieldNumber, FieldCodec<TValue> codec) : base(fieldNumber) 53 { 54 this.codec = codec; 55 } 56 57 internal TValue DefaultValue => codec != null ? codec.DefaultValue : default; 58 59 internal override Type TargetType => typeof(TTarget); 60 61 internal override bool IsRepeated => false; 62 CreateValue()63 internal override IExtensionValue CreateValue() 64 { 65 return new ExtensionValue<TValue>(codec); 66 } 67 } 68 69 /// <summary> 70 /// Represents a type-safe extension identifier used for getting repeated extension values in <see cref="IExtendableMessage{T}"/> instances. 71 /// This API is experimental and subject to change. 72 /// </summary> 73 /// <typeparam name="TTarget">The message type this field applies to</typeparam> 74 /// <typeparam name="TValue">The repeated field value type of this extension</typeparam> 75 public sealed class RepeatedExtension<TTarget, TValue> : Extension where TTarget : IExtendableMessage<TTarget> 76 { 77 private readonly FieldCodec<TValue> codec; 78 79 /// <summary> 80 /// Creates a new repeated extension identifier with the specified field number and codec 81 /// </summary> RepeatedExtension(int fieldNumber, FieldCodec<TValue> codec)82 public RepeatedExtension(int fieldNumber, FieldCodec<TValue> codec) : base(fieldNumber) 83 { 84 this.codec = codec; 85 } 86 87 internal override Type TargetType => typeof(TTarget); 88 89 internal override bool IsRepeated => true; 90 CreateValue()91 internal override IExtensionValue CreateValue() 92 { 93 return new RepeatedExtensionValue<TValue>(codec); 94 } 95 } 96 } 97