#region Copyright notice and license
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// 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.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#endregion
using Google.Protobuf.Compatibility;
using System;
namespace Google.Protobuf.Reflection
{
/// <summary>
/// Descriptor for a field or extension within a message in a .proto file.
/// </summary>
public sealed class FieldDescriptor : DescriptorBase, IComparable<FieldDescriptor>
{
private EnumDescriptor enumType;
private MessageDescriptor messageType;
private FieldType fieldType;
private readonly string propertyName; // Annoyingly, needed in Crosslink.
private IFieldAccessor accessor;
/// <summary>
/// Get the field's containing message type.
/// </summary>
public MessageDescriptor ContainingType { get; }
/// <summary>
/// Returns the oneof containing this field, or <c>null</c> if it is not part of a oneof.
/// </summary>
public OneofDescriptor ContainingOneof { get; }
/// <summary>
/// The effective JSON name for this field. This is usually the lower-camel-cased form of the field name,
/// but can be overridden using the <c>json_name</c> option in the .proto file.
/// </summary>
public string JsonName { get; }
internal FieldDescriptorProto Proto { get; }
internal FieldDescriptor(FieldDescriptorProto proto, FileDescriptor file,
MessageDescriptor parent, int index, string propertyName)
: base(file, file.ComputeFullName(parent, proto.Name), index)
{
Proto = proto;
if (proto.Type != 0)
{
fieldType = GetFieldTypeFromProtoType(proto.Type);
}
if (FieldNumber <= 0)
{
throw new DescriptorValidationException(this, "Field numbers must be positive integers.");
}
ContainingType = parent;
// OneofIndex "defaults" to -1 due to a hack in FieldDescriptor.OnConstruction.
if (proto.OneofIndex != -1)
{
if (proto.OneofIndex < 0 || proto.OneofIndex >= parent.Proto.OneofDecl.Count)
{
throw new DescriptorValidationException(this,
$"FieldDescriptorProto.oneof_index is out of range for type {parent.Name}");
}
ContainingOneof = parent.Oneofs[proto.OneofIndex];
}
file.DescriptorPool.AddSymbol(this);
// We can't create the accessor until we've cross-linked, unfortunately, as we
// may not know whether the type of the field is a map or not. Remember the property name
// for later.
// We could trust the generated code and check whether the type of the property is
// a MapField, but that feels a tad nasty.
this.propertyName = propertyName;
JsonName = Proto.JsonName == "" ? JsonFormatter.ToCamelCase(Proto.Name) : Proto.JsonName;
}
/// <summary>
/// The brief name of the descriptor's target.
/// </summary>
public override string Name => Proto.Name;
/// <summary>
/// Returns the accessor for this field.
/// </summary>
/// <remarks>
/// <para>
/// While a <see cref="FieldDescriptor"/> describes the field, it does not provide
/// any way of obtaining or changing the value of the field within a specific message;
/// that is the responsibility of the accessor.
/// </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. This is not represented in any
/// generated type, and the value of the map field itself is represented by a dictionary in the
/// reflection API. There are never instances of those "hidden" messages, so no accessor is provided
/// and this property will return null.
/// </para>
/// </remarks>
public IFieldAccessor Accessor => accessor;
/// <summary>
/// Maps a field type as included in the .proto file to a FieldType.
/// </summary>
private static FieldType GetFieldTypeFromProtoType(FieldDescriptorProto.Types.Type type)
{
switch (type)
{
case FieldDescriptorProto.Types.Type.Double:
return FieldType.Double;
case FieldDescriptorProto.Types.Type.Float:
return FieldType.Float;
case FieldDescriptorProto.Types.Type.Int64:
return FieldType.Int64;
case FieldDescriptorProto.Types.Type.Uint64:
return FieldType.UInt64;
case FieldDescriptorProto.Types.Type.Int32:
return FieldType.Int32;
case FieldDescriptorProto.Types.Type.Fixed64:
return FieldType.Fixed64;
case FieldDescriptorProto.Types.Type.Fixed32:
return FieldType.Fixed32;
case FieldDescriptorProto.Types.Type.Bool:
return FieldType.Bool;
case FieldDescriptorProto.Types.Type.String:
return FieldType.String;
case FieldDescriptorProto.Types.Type.Group:
return FieldType.Group;
case FieldDescriptorProto.Types.Type.Message:
return FieldType.Message;
case FieldDescriptorProto.Types.Type.Bytes:
return FieldType.Bytes;
case FieldDescriptorProto.Types.Type.Uint32:
return FieldType.UInt32;
case FieldDescriptorProto.Types.Type.Enum:
return FieldType.Enum;
case FieldDescriptorProto.Types.Type.Sfixed32:
return FieldType.SFixed32;
case FieldDescriptorProto.Types.Type.Sfixed64:
return FieldType.SFixed64;
case FieldDescriptorProto.Types.Type.Sint32:
return FieldType.SInt32;
case FieldDescriptorProto.Types.Type.Sint64:
return FieldType.SInt64;
default:
throw new ArgumentException("Invalid type specified");
}
}
/// <summary>
/// Returns <c>true</c> if this field is a repeated field; <c>false</c> otherwise.
/// </summary>
public bool IsRepeated => Proto.Label == FieldDescriptorProto.Types.Label.Repeated;
/// <summary>
/// Returns <c>true</c> if this field is a map field; <c>false</c> otherwise.
/// </summary>
public bool IsMap => fieldType == FieldType.Message && messageType.Proto.Options != null && messageType.Proto.Options.MapEntry;
/// <summary>
/// Returns <c>true</c> if this field is a packed, repeated field; <c>false</c> otherwise.
/// </summary>
public bool IsPacked =>
// Note the || rather than && here - we're effectively defaulting to packed, because that *is*
// the default in proto3, which is all we support. We may give the wrong result for the protos
// within descriptor.proto, but that's okay, as they're never exposed and we don't use IsPacked
// within the runtime.
Proto.Options == null || Proto.Options.Packed;
/// <summary>
/// Returns the type of the field.
/// </summary>
public FieldType FieldType => fieldType;
/// <summary>
/// Returns the field number declared in the proto file.
/// </summary>
public int FieldNumber => Proto.Number;
/// <summary>
/// Compares this descriptor with another one, ordering in "canonical" order
/// which simply means ascending order by field number. <paramref name="other"/>
/// must be a field of the same type, i.e. the <see cref="ContainingType"/> of
/// both fields must be the same.
/// </summary>
public int CompareTo(FieldDescriptor other)
{
if (other.ContainingType != ContainingType)
{
throw new ArgumentException("FieldDescriptors can only be compared to other FieldDescriptors " +
"for fields of the same message type.");
}
return FieldNumber - other.FieldNumber;
}
/// <summary>
/// For enum fields, returns the field's type.
/// </summary>
public EnumDescriptor EnumType
{
get
{
if (fieldType != FieldType.Enum)
{
throw new InvalidOperationException("EnumType is only valid for enum fields.");
}
return enumType;
}
}
/// <summary>
/// For embedded message and group fields, returns the field's type.
/// </summary>
public MessageDescriptor MessageType
{
get
{
if (fieldType != FieldType.Message)
{
throw new InvalidOperationException("MessageType is only valid for message fields.");
}
return messageType;
}
}
/// <summary>
/// Look up and cross-link all field types etc.
/// </summary>
internal void CrossLink()
{
if (Proto.TypeName != "")
{
IDescriptor typeDescriptor =
File.DescriptorPool.LookupSymbol(Proto.TypeName, this);
if (Proto.Type != 0)
{
// Choose field type based on symbol.
if (typeDescriptor is MessageDescriptor)
{
fieldType = FieldType.Message;
}
else if (typeDescriptor is EnumDescriptor)
{
fieldType = FieldType.Enum;
}
else
{
throw new DescriptorValidationException(this, $"\"{Proto.TypeName}\" is not a type.");
}
}
if (fieldType == FieldType.Message)
{
if (!(typeDescriptor is MessageDescriptor))
{
throw new DescriptorValidationException(this, $"\"{Proto.TypeName}\" is not a message type.");
}
messageType = (MessageDescriptor) typeDescriptor;
if (Proto.DefaultValue != "")
{
throw new DescriptorValidationException(this, "Messages can't have default values.");
}
}
else if (fieldType == FieldType.Enum)
{
if (!(typeDescriptor is EnumDescriptor))
{
throw new DescriptorValidationException(this, $"\"{Proto.TypeName}\" is not an enum type.");
}
enumType = (EnumDescriptor) typeDescriptor;
}
else
{
throw new DescriptorValidationException(this, "Field with primitive type has type_name.");
}
}
else
{
if (fieldType == FieldType.Message || fieldType == FieldType.Enum)
{
throw new DescriptorValidationException(this, "Field with message or enum type missing type_name.");
}
}
// Note: no attempt to perform any default value parsing
File.DescriptorPool.AddFieldByNumber(this);
if (ContainingType != null && ContainingType.Proto.Options != null && ContainingType.Proto.Options.MessageSetWireFormat)
{
throw new DescriptorValidationException(this, "MessageSet format is not supported.");
}
accessor = CreateAccessor();
}
private IFieldAccessor CreateAccessor()
{
// If we're given no property name, that's because we really don't want an accessor.
// (At the moment, that means it's a map entry message...)
if (propertyName == null)
{
return null;
}
var property = ContainingType.ClrType.GetProperty(propertyName);
if (property == null)
{
throw new DescriptorValidationException(this, $"Property {propertyName} not found in {ContainingType.ClrType}");
}
return IsMap ? new MapFieldAccessor(property, this)
: IsRepeated ? new RepeatedFieldAccessor(property, this)
: (IFieldAccessor) new SingleFieldAccessor(property, this);
}
}
}