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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;
using Google.ProtocolBuffers.Descriptors;
namespace Google.ProtocolBuffers.FieldAccess {
/// <summary>
/// Provides access to fields in generated messages via reflection.
/// This type is public to allow it to be used by generated messages, which
/// create appropriate instances in the .proto file description class.
/// TODO(jonskeet): See if we can hide it somewhere...
/// </summary>
public sealed class FieldAccessorTable<TMessage, TBuilder>
where TMessage : IMessage<TMessage, TBuilder>
where TBuilder : IBuilder<TMessage, TBuilder> {
readonly IFieldAccessor<TMessage, TBuilder>[] accessors;
readonly MessageDescriptor descriptor;
public MessageDescriptor Descriptor {
get { return descriptor; }
}
/// <summary>
/// Constructs a FieldAccessorTable for a particular message class.
/// Only one FieldAccessorTable should be constructed per class.
/// </summary>
/// <param name="descriptor">The type's descriptor</param>
/// <param name="propertyNames">The Pascal-case names of all the field-based properties in the message.</param>
public FieldAccessorTable(MessageDescriptor descriptor, String[] propertyNames) {
this.descriptor = descriptor;
accessors = new IFieldAccessor<TMessage, TBuilder>[descriptor.Fields.Count];
for (int i=0; i < accessors.Length; i++) {
accessors[i] = CreateAccessor(descriptor.Fields[i], propertyNames[i]);
}
}
/// <summary>
/// Creates an accessor for a single field
/// </summary>
private static IFieldAccessor<TMessage, TBuilder> CreateAccessor(FieldDescriptor field, string name) {
if (field.IsRepeated) {
switch (field.MappedType) {
case MappedType.Message: return new RepeatedMessageAccessor<TMessage, TBuilder>(name);
case MappedType.Enum: return new RepeatedEnumAccessor<TMessage, TBuilder>(field, name);
default: return new RepeatedPrimitiveAccessor<TMessage, TBuilder>(name);
}
} else {
switch (field.MappedType) {
case MappedType.Message: return new SingleMessageAccessor<TMessage, TBuilder>(name);
case MappedType.Enum: return new SingleEnumAccessor<TMessage, TBuilder>(field, name);
default: return new SinglePrimitiveAccessor<TMessage, TBuilder>(name);
}
}
}
internal IFieldAccessor<TMessage, TBuilder> this[FieldDescriptor field] {
get {
if (field.ContainingType != descriptor) {
throw new ArgumentException("FieldDescriptor does not match message type.");
} else if (field.IsExtension) {
// If this type had extensions, it would subclass ExtendableMessage,
// which overrides the reflection interface to handle extensions.
throw new ArgumentException("This type does not have extensions.");
}
return accessors[field.Index];
}
}
}
}
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