75 lines
2.8 KiB
C#
75 lines
2.8 KiB
C#
#region Copyright notice and license
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// Protocol Buffers - Google's data interchange format
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// Copyright 2015 Google Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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#endregion
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using System;
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using System.Reflection;
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using Google.Protobuf.Compatibility;
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namespace Google.Protobuf.Reflection
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{
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/// <summary>
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/// Reflection access for a oneof, allowing clear and "get case" actions.
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/// </summary>
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public sealed class OneofAccessor
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{
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private readonly Func<IMessage, int> caseDelegate;
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private readonly Action<IMessage> clearDelegate;
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private OneofAccessor(OneofDescriptor descriptor, Func<IMessage, int> caseDelegate, Action<IMessage> clearDelegate)
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{
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Descriptor = descriptor;
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this.caseDelegate = caseDelegate;
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this.clearDelegate = clearDelegate;
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}
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internal static OneofAccessor ForRegularOneof(
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OneofDescriptor descriptor,
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PropertyInfo caseProperty,
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MethodInfo clearMethod) =>
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new OneofAccessor(
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descriptor,
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ReflectionUtil.CreateFuncIMessageInt32(caseProperty.GetGetMethod()),
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ReflectionUtil.CreateActionIMessage(clearMethod));
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internal static OneofAccessor ForSyntheticOneof(OneofDescriptor descriptor)
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{
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// Note: descriptor.Fields will be null when this method is called, because we haven't
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// cross-linked yet. But by the time the delegates are called by user code, all will be
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// well. (That's why we capture the descriptor itself rather than a field.)
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return new OneofAccessor(descriptor,
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message => descriptor.Fields[0].Accessor.HasValue(message) ? descriptor.Fields[0].FieldNumber : 0,
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message => descriptor.Fields[0].Accessor.Clear(message));
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}
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/// <summary>
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/// Gets the descriptor for this oneof.
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/// </summary>
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/// <value>
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/// The descriptor of the oneof.
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/// </value>
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public OneofDescriptor Descriptor { get; }
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/// <summary>
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/// Clears the oneof in the specified message.
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/// </summary>
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public void Clear(IMessage message) => clearDelegate(message);
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/// <summary>
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/// Indicates which field in the oneof is set for specified message
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/// </summary>
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public FieldDescriptor GetCaseFieldDescriptor(IMessage message)
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{
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int fieldNumber = caseDelegate(message);
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return fieldNumber > 0
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? Descriptor.ContainingType.FindFieldByNumber(fieldNumber)
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: null;
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}
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}
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}
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