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#region Copyright notice and license
// Copyright 2015 gRPC authors.
//
// 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.
#endregion
using System;
using Grpc.Core.Utils;
namespace Grpc.Core
{
/// <summary>
/// Encapsulates the logic for serializing and deserializing messages.
/// </summary>
public class Marshaller<T>
{
readonly Func<T, byte[]> serializer;
readonly Func<byte[], T> deserializer;
readonly Action<T, SerializationContext> contextualSerializer;
readonly Func<DeserializationContext, T> contextualDeserializer;
/// <summary>
/// Initializes a new marshaller from simple serialize/deserialize functions.
/// </summary>
/// <param name="serializer">Function that will be used to serialize messages.</param>
/// <param name="deserializer">Function that will be used to deserialize messages.</param>
public Marshaller(Func<T, byte[]> serializer, Func<byte[], T> deserializer)
{
this.serializer = GrpcPreconditions.CheckNotNull(serializer, nameof(serializer));
this.deserializer = GrpcPreconditions.CheckNotNull(deserializer, nameof(deserializer));
// contextual serialization/deserialization is emulated to make the marshaller
// usable with the grpc library (required for backward compatibility).
this.contextualSerializer = EmulateContextualSerializer;
this.contextualDeserializer = EmulateContextualDeserializer;
}
/// <summary>
/// Initializes a new marshaller from serialize/deserialize fuctions that can access serialization and deserialization
/// context. Compared to the simple serializer/deserializer functions, using the contextual version provides more
/// flexibility and can lead to increased efficiency (and better performance).
/// Note: This constructor is part of an experimental API that can change or be removed without any prior notice.
/// </summary>
/// <param name="serializer">Function that will be used to serialize messages.</param>
/// <param name="deserializer">Function that will be used to deserialize messages.</param>
public Marshaller(Action<T, SerializationContext> serializer, Func<DeserializationContext, T> deserializer)
{
this.contextualSerializer = GrpcPreconditions.CheckNotNull(serializer, nameof(serializer));
this.contextualDeserializer = GrpcPreconditions.CheckNotNull(deserializer, nameof(deserializer));
// gRPC only uses contextual serializer/deserializer internally, so emulating the legacy
// (de)serializer is not necessary.
this.serializer = (msg) => { throw new NotImplementedException(); };
this.deserializer = (payload) => { throw new NotImplementedException(); };
}
/// <summary>
/// Gets the serializer function.
/// </summary>
public Func<T, byte[]> Serializer => this.serializer;
/// <summary>
/// Gets the deserializer function.
/// </summary>
public Func<byte[], T> Deserializer => this.deserializer;
/// <summary>
/// Gets the serializer function.
/// Note: experimental API that can change or be removed without any prior notice.
/// </summary>
public Action<T, SerializationContext> ContextualSerializer => this.contextualSerializer;
/// <summary>
/// Gets the serializer function.
/// Note: experimental API that can change or be removed without any prior notice.
/// </summary>
public Func<DeserializationContext, T> ContextualDeserializer => this.contextualDeserializer;
// for backward compatibility, emulate the contextual serializer using the simple one
private void EmulateContextualSerializer(T message, SerializationContext context)
{
var payload = this.serializer(message);
context.Complete(payload);
}
// for backward compatibility, emulate the contextual deserializer using the simple one
private T EmulateContextualDeserializer(DeserializationContext context)
{
return this.deserializer(context.PayloadAsNewBuffer());
}
}
/// <summary>
/// Utilities for creating marshallers.
/// </summary>
public static class Marshallers
{
/// <summary>
/// Creates a marshaller from specified serializer and deserializer.
/// </summary>
public static Marshaller<T> Create<T>(Func<T, byte[]> serializer, Func<byte[], T> deserializer)
{
return new Marshaller<T>(serializer, deserializer);
}
/// <summary>
/// Creates a marshaller from specified contextual serializer and deserializer.
/// Note: This method is part of an experimental API that can change or be removed without any prior notice.
/// </summary>
public static Marshaller<T> Create<T>(Action<T, SerializationContext> serializer, Func<DeserializationContext, T> deserializer)
{
return new Marshaller<T>(serializer, deserializer);
}
/// <summary>
/// Returns a marshaller for <c>string</c> type. This is useful for testing.
/// </summary>
public static Marshaller<string> StringMarshaller
{
get
{
return new Marshaller<string>(System.Text.Encoding.UTF8.GetBytes,
System.Text.Encoding.UTF8.GetString);
}
}
}
}
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