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MessageDescriptor.cs
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MessageDescriptor.cs
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#region Copyright notice and license
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
#endregion
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
namespace Google.Protobuf.Reflection
{
/// <summary>
/// Describes a message type.
/// </summary>
public sealed class MessageDescriptor : DescriptorBase
{
private static readonly HashSet<string> WellKnownTypeNames = new HashSet<string>
{
"google/protobuf/any.proto",
"google/protobuf/api.proto",
"google/protobuf/duration.proto",
"google/protobuf/empty.proto",
"google/protobuf/wrappers.proto",
"google/protobuf/timestamp.proto",
"google/protobuf/field_mask.proto",
"google/protobuf/source_context.proto",
"google/protobuf/struct.proto",
"google/protobuf/type.proto",
};
private readonly IList<FieldDescriptor> fieldsInDeclarationOrder;
private readonly IList<FieldDescriptor> fieldsInNumberOrder;
private readonly IDictionary<string, FieldDescriptor> jsonFieldMap;
private Func<IMessage, bool> extensionSetIsInitialized;
internal MessageDescriptor(DescriptorProto proto, FileDescriptor file, MessageDescriptor parent, int typeIndex, GeneratedClrTypeInfo generatedCodeInfo)
: base(file, file.ComputeFullName(parent, proto.Name), typeIndex, (parent?.Features ?? file.Features).MergedWith(proto.Options?.Features))
{
Proto = proto;
Parser = generatedCodeInfo?.Parser;
ClrType = generatedCodeInfo?.ClrType;
ContainingType = parent;
// If generatedCodeInfo is null, we just won't generate an accessor for any fields.
Oneofs = DescriptorUtil.ConvertAndMakeReadOnly(
proto.OneofDecl,
(oneof, index) =>
new OneofDescriptor(oneof, file, this, index, generatedCodeInfo?.OneofNames[index]));
int syntheticOneofCount = 0;
foreach (var oneof in Oneofs)
{
if (oneof.IsSynthetic)
{
syntheticOneofCount++;
}
else if (syntheticOneofCount != 0)
{
throw new ArgumentException("All synthetic oneofs should come after real oneofs");
}
}
RealOneofCount = Oneofs.Count - syntheticOneofCount;
NestedTypes = DescriptorUtil.ConvertAndMakeReadOnly(
proto.NestedType,
(type, index) =>
new MessageDescriptor(type, file, this, index, generatedCodeInfo?.NestedTypes[index]));
EnumTypes = DescriptorUtil.ConvertAndMakeReadOnly(
proto.EnumType,
(type, index) =>
new EnumDescriptor(type, file, this, index, generatedCodeInfo?.NestedEnums[index]));
Extensions = new ExtensionCollection(this, generatedCodeInfo?.Extensions);
fieldsInDeclarationOrder = DescriptorUtil.ConvertAndMakeReadOnly(
proto.Field,
(field, index) =>
new FieldDescriptor(field, file, this, index, generatedCodeInfo?.PropertyNames[index], null));
fieldsInNumberOrder = new ReadOnlyCollection<FieldDescriptor>(fieldsInDeclarationOrder.OrderBy(field => field.FieldNumber).ToArray());
// TODO: Use field => field.Proto.JsonName when we're confident it's appropriate. (And then use it in the formatter, too.)
jsonFieldMap = CreateJsonFieldMap(fieldsInNumberOrder);
file.DescriptorPool.AddSymbol(this);
Fields = new FieldCollection(this);
}
private static ReadOnlyDictionary<string, FieldDescriptor> CreateJsonFieldMap(IList<FieldDescriptor> fields)
{
var map = new Dictionary<string, FieldDescriptor>();
// The ordering is important here: JsonName takes priority over Name,
// which means we need to put JsonName values in the map after *all*
// Name keys have been added. See https://github.com/protocolbuffers/protobuf/issues/11987
foreach (var field in fields)
{
map[field.Name] = field;
}
foreach (var field in fields)
{
map[field.JsonName] = field;
}
return new ReadOnlyDictionary<string, FieldDescriptor>(map);
}
/// <summary>
/// The brief name of the descriptor's target.
/// </summary>
public override string Name => Proto.Name;
internal override IReadOnlyList<DescriptorBase> GetNestedDescriptorListForField(int fieldNumber) =>
fieldNumber switch
{
DescriptorProto.FieldFieldNumber => (IReadOnlyList<DescriptorBase>)fieldsInDeclarationOrder,
DescriptorProto.NestedTypeFieldNumber => (IReadOnlyList<DescriptorBase>)NestedTypes,
DescriptorProto.EnumTypeFieldNumber => (IReadOnlyList<DescriptorBase>)EnumTypes,
DescriptorProto.OneofDeclFieldNumber => (IReadOnlyList<DescriptorBase>)Oneofs,
_ => null,
};
internal DescriptorProto Proto { get; }
/// <summary>
/// Returns a clone of the underlying <see cref="DescriptorProto"/> describing this message.
/// Note that a copy is taken every time this method is called, so clients using it frequently
/// (and not modifying it) may want to cache the returned value.
/// </summary>
/// <returns>A protobuf representation of this message descriptor.</returns>
public DescriptorProto ToProto() => Proto.Clone();
internal bool IsExtensionsInitialized(IMessage message)
{
if (Proto.ExtensionRange.Count == 0)
{
return true;
}
if (extensionSetIsInitialized == null)
{
extensionSetIsInitialized = ReflectionUtil.CreateIsInitializedCaller(ClrType);
}
return extensionSetIsInitialized(message);
}
/// <summary>
/// The CLR type used to represent message instances from this descriptor.
/// </summary>
/// <remarks>
/// <para>
/// The value returned by this property will be non-null for all regular fields. However,
/// if a message containing a map field is introspected, the list of nested messages will include
/// an auto-generated nested key/value pair message for the field. This is not represented in any
/// generated type, so this property will return null in such cases.
/// </para>
/// <para>
/// For wrapper types (<see cref="Google.Protobuf.WellKnownTypes.StringValue"/> and the like), the type returned here
/// will be the generated message type, not the native type used by reflection for fields of those types. Code
/// using reflection should call <see cref="IsWrapperType"/> to determine whether a message descriptor represents
/// a wrapper type, and handle the result appropriately.
/// </para>
/// </remarks>
[DynamicallyAccessedMembers(GeneratedClrTypeInfo.MessageAccessibility)]
public Type ClrType { get; }
/// <summary>
/// A parser for this message type.
/// </summary>
/// <remarks>
/// <para>
/// As <see cref="MessageDescriptor"/> is not generic, this cannot be statically
/// typed to the relevant type, but it should produce objects of a type compatible with <see cref="ClrType"/>.
/// </para>
/// <para>
/// The value returned by this property will be non-null for all regular fields. However,
/// if a message containing a map field is introspected, the list of nested messages will include
/// an auto-generated nested key/value pair message for the field. No message parser object is created for
/// such messages, so this property will return null in such cases.
/// </para>
/// <para>
/// For wrapper types (<see cref="Google.Protobuf.WellKnownTypes.StringValue"/> and the like), the parser returned here
/// will be the generated message type, not the native type used by reflection for fields of those types. Code
/// using reflection should call <see cref="IsWrapperType"/> to determine whether a message descriptor represents
/// a wrapper type, and handle the result appropriately.
/// </para>
/// </remarks>
public MessageParser Parser { get; }
/// <summary>
/// Returns whether this message is one of the "well known types" which may have runtime/protoc support.
/// </summary>
internal bool IsWellKnownType => File.Package == "google.protobuf" && WellKnownTypeNames.Contains(File.Name);
/// <summary>
/// Returns whether this message is one of the "wrapper types" used for fields which represent primitive values
/// with the addition of presence.
/// </summary>
internal bool IsWrapperType => File.Package == "google.protobuf" && File.Name == "google/protobuf/wrappers.proto";
/// <summary>
/// Returns whether this message was synthetically-created to store key/value pairs in a
/// map field.
/// </summary>
public bool IsMapEntry => Proto.Options?.MapEntry == true;
/// <value>
/// If this is a nested type, get the outer descriptor, otherwise null.
/// </value>
public MessageDescriptor ContainingType { get; }
/// <value>
/// A collection of fields, which can be retrieved by name or field number.
/// </value>
public FieldCollection Fields { get; }
/// <summary>
/// An unmodifiable list of extensions defined in this message's scope.
/// Note that some extensions may be incomplete (FieldDescriptor.Extension may be null)
/// if they are declared in a file generated using a version of protoc that did not fully
/// support extensions in C#.
/// </summary>
public ExtensionCollection Extensions { get; }
/// <value>
/// An unmodifiable list of this message type's nested types.
/// </value>
public IList<MessageDescriptor> NestedTypes { get; }
/// <value>
/// An unmodifiable list of this message type's enum types.
/// </value>
public IList<EnumDescriptor> EnumTypes { get; }
/// <value>
/// An unmodifiable list of the "oneof" field collections in this message type.
/// All "real" oneofs (where <see cref="OneofDescriptor.IsSynthetic"/> returns false)
/// come before synthetic ones.
/// </value>
public IList<OneofDescriptor> Oneofs { get; }
/// <summary>
/// The number of real "oneof" descriptors in this message type. Every element in <see cref="Oneofs"/>
/// with an index less than this will have a <see cref="OneofDescriptor.IsSynthetic"/> property value
/// of <c>false</c>; every element with an index greater than or equal to this will have a
/// <see cref="OneofDescriptor.IsSynthetic"/> property value of <c>true</c>.
/// </summary>
public int RealOneofCount { get; }
/// <summary>
/// Finds a field by field name.
/// </summary>
/// <param name="name">The unqualified name of the field (e.g. "foo").</param>
/// <returns>The field's descriptor, or null if not found.</returns>
public FieldDescriptor FindFieldByName(string name) => File.DescriptorPool.FindSymbol<FieldDescriptor>(FullName + "." + name);
/// <summary>
/// Finds a field by field number.
/// </summary>
/// <param name="number">The field number within this message type.</param>
/// <returns>The field's descriptor, or null if not found.</returns>
public FieldDescriptor FindFieldByNumber(int number) => File.DescriptorPool.FindFieldByNumber(this, number);
/// <summary>
/// Finds a nested descriptor by name. The is valid for fields, nested
/// message types, oneofs and enums.
/// </summary>
/// <param name="name">The unqualified name of the descriptor, e.g. "Foo"</param>
/// <returns>The descriptor, or null if not found.</returns>
public T FindDescriptor<T>(string name) where T : class, IDescriptor =>
File.DescriptorPool.FindSymbol<T>(FullName + "." + name);
/// <summary>
/// The (possibly empty) set of custom options for this message.
/// </summary>
[Obsolete("CustomOptions are obsolete. Use the GetOptions() method.")]
public CustomOptions CustomOptions => new CustomOptions(Proto.Options?._extensions?.ValuesByNumber);
/// <summary>
/// The <c>MessageOptions</c>, defined in <c>descriptor.proto</c>.
/// If the options message is not present (i.e. there are no options), <c>null</c> is returned.
/// Custom options can be retrieved as extensions of the returned message.
/// NOTE: A defensive copy is created each time this property is retrieved.
/// </summary>
public MessageOptions GetOptions()
{
var clone = Proto.Options?.Clone();
if (clone is null)
{
return null;
}
// Clients should be using feature accessor methods, not accessing features on the
// options proto.
clone.Features = null;
return clone;
}
/// <summary>
/// Gets a single value message option for this descriptor
/// </summary>
[Obsolete("GetOption is obsolete. Use the GetOptions() method.")]
public T GetOption<T>(Extension<MessageOptions, T> extension)
{
var value = Proto.Options.GetExtension(extension);
return value is IDeepCloneable<T> ? (value as IDeepCloneable<T>).Clone() : value;
}
/// <summary>
/// Gets a repeated value message option for this descriptor
/// </summary>
[Obsolete("GetOption is obsolete. Use the GetOptions() method.")]
public Collections.RepeatedField<T> GetOption<T>(RepeatedExtension<MessageOptions, T> extension)
{
return Proto.Options.GetExtension(extension).Clone();
}
/// <summary>
/// Looks up and cross-links all fields and nested types.
/// </summary>
internal void CrossLink()
{
foreach (MessageDescriptor message in NestedTypes)
{
message.CrossLink();
}
foreach (FieldDescriptor field in fieldsInDeclarationOrder)
{
field.CrossLink();
}
foreach (OneofDescriptor oneof in Oneofs)
{
oneof.CrossLink();
}
Extensions.CrossLink();
}
/// <summary>
/// A collection to simplify retrieving the field accessor for a particular field.
/// </summary>
[DebuggerDisplay("Count = {InFieldNumberOrder().Count}")]
[DebuggerTypeProxy(typeof(FieldCollectionDebugView))]
public sealed class FieldCollection
{
private readonly MessageDescriptor messageDescriptor;
internal FieldCollection(MessageDescriptor messageDescriptor)
{
this.messageDescriptor = messageDescriptor;
}
/// <value>
/// Returns the fields in the message as an immutable list, in the order in which they
/// are declared in the source .proto file.
/// </value>
public IList<FieldDescriptor> InDeclarationOrder() => messageDescriptor.fieldsInDeclarationOrder;
/// <value>
/// Returns the fields in the message as an immutable list, in ascending field number
/// order. Field numbers need not be contiguous, so there is no direct mapping from the
/// index in the list to the field number; to retrieve a field by field number, it is better
/// to use the <see cref="FieldCollection"/> indexer.
/// </value>
public IList<FieldDescriptor> InFieldNumberOrder() => messageDescriptor.fieldsInNumberOrder;
// TODO: consider making this public in the future. (Being conservative for now...)
/// <value>
/// Returns a read-only dictionary mapping the field names in this message as they're available
/// in the JSON representation to the field descriptors. For example, a field <c>foo_bar</c>
/// in the message would result two entries, one with a key <c>fooBar</c> and one with a key
/// <c>foo_bar</c>, both referring to the same field.
/// </value>
internal IDictionary<string, FieldDescriptor> ByJsonName() => messageDescriptor.jsonFieldMap;
/// <summary>
/// Retrieves the descriptor for the field with the given number.
/// </summary>
/// <param name="number">Number of the field to retrieve the descriptor for</param>
/// <returns>The accessor for the given field</returns>
/// <exception cref="KeyNotFoundException">The message descriptor does not contain a field
/// with the given number</exception>
public FieldDescriptor this[int number]
{
get
{
var fieldDescriptor = messageDescriptor.FindFieldByNumber(number);
if (fieldDescriptor == null)
{
throw new KeyNotFoundException("No such field number");
}
return fieldDescriptor;
}
}
/// <summary>
/// Retrieves the descriptor for the field with the given name.
/// </summary>
/// <param name="name">Name of the field to retrieve the descriptor for</param>
/// <returns>The descriptor for the given field</returns>
/// <exception cref="KeyNotFoundException">The message descriptor does not contain a field
/// with the given name</exception>
public FieldDescriptor this[string name]
{
get
{
var fieldDescriptor = messageDescriptor.FindFieldByName(name);
if (fieldDescriptor == null)
{
throw new KeyNotFoundException("No such field name");
}
return fieldDescriptor;
}
}
private sealed class FieldCollectionDebugView
{
private readonly FieldCollection collection;
public FieldCollectionDebugView(FieldCollection collection)
{
this.collection = collection;
}
[DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
public FieldDescriptor[] Items => collection.InFieldNumberOrder().ToArray();
}
}
}
}