protobuf/src/ProtocolBuffers/FieldAccess/SinglePrimitiveAccessor.cs

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// http://github.com/jskeet/dotnet-protobufs/
// Original C++/Java/Python code:
// http://code.google.com/p/protobuf/
//
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// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
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// contributors may be used to endorse or promote products derived from
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using System;
using System.Reflection;

namespace Google.ProtocolBuffers.FieldAccess {
  /// <summary>
  /// Access for a non-repeated field of a "primitive" type (i.e. not another message or an enum).
  /// </summary>
  internal class SinglePrimitiveAccessor<TMessage, TBuilder> : IFieldAccessor<TMessage, TBuilder>
      where TMessage : IMessage<TMessage, TBuilder>
      where TBuilder : IBuilder<TMessage, TBuilder> {

    private readonly Type clrType;
    private readonly Func<TMessage, object> getValueDelegate;
    private readonly Action<TBuilder, object> setValueDelegate;
    private readonly Func<TMessage, bool> hasDelegate;
    private readonly Func<TBuilder, IBuilder> clearDelegate;

    /// <summary>
    /// The CLR type of the field (int, the enum type, ByteString, the message etc).
    /// As declared by the property.
    /// </summary>
    protected Type ClrType {
      get { return clrType; }
    }

    internal SinglePrimitiveAccessor(string name) {

      string propertyName = name == typeof(TMessage).Name ? name + "_" : name;
      PropertyInfo messageProperty = typeof(TMessage).GetProperty(propertyName);
      PropertyInfo builderProperty = typeof(TBuilder).GetProperty(name); // FIXME!
      if (builderProperty == null) builderProperty = typeof(TBuilder).GetProperty(propertyName); // FIXME!
      PropertyInfo hasProperty = typeof(TMessage).GetProperty("Has" + name);
      MethodInfo clearMethod = typeof(TBuilder).GetMethod("Clear" + name, Type.EmptyTypes);
      if (messageProperty == null || builderProperty == null || hasProperty == null || clearMethod == null) {
        throw new ArgumentException("Not all required properties/methods available");
      }
      clrType = messageProperty.PropertyType;
      hasDelegate = (Func<TMessage, bool>)Delegate.CreateDelegate(typeof(Func<TMessage, bool>), hasProperty.GetGetMethod());
      clearDelegate = (Func<TBuilder, IBuilder>)Delegate.CreateDelegate(typeof(Func<TBuilder, IBuilder>), clearMethod);
      getValueDelegate = ReflectionUtil.CreateUpcastDelegate<TMessage>(messageProperty.GetGetMethod());
      setValueDelegate = ReflectionUtil.CreateDowncastDelegate<TBuilder>(builderProperty.GetSetMethod());
    }

    public bool Has(TMessage message) {
      return hasDelegate(message);
    }

    public void Clear(TBuilder builder) {
      clearDelegate(builder);
    }

    /// <summary>
    /// Only valid for message types - this implementation throws InvalidOperationException.
    /// </summary>
    public virtual IBuilder CreateBuilder() {
      throw new InvalidOperationException();
    }

    public virtual object GetValue(TMessage message) {
      return getValueDelegate(message);
    }

    public virtual void SetValue(TBuilder builder, object value) {
      setValueDelegate(builder, value);
    }

    #region Methods only related to repeated values
    public int GetRepeatedCount(TMessage message) {
      throw new InvalidOperationException();
    }

    public object GetRepeatedValue(TMessage message, int index) {
      throw new InvalidOperationException();
    }

    public void SetRepeated(TBuilder builder, int index, object value) {
      throw new InvalidOperationException();
    }

    public void AddRepeated(TBuilder builder, object value) {
      throw new InvalidOperationException();
    }

    public object GetRepeatedWrapper(TBuilder builder) {
      throw new InvalidOperationException();
    }
    #endregion
  }
}