IMessage.cs

#region Copyright notice and license

// 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/
//
// 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 System;
using System.Collections.Generic;
using System.IO;
using Google.ProtocolBuffers.Descriptors;

namespace Google.ProtocolBuffers
{
    /// <summary>
    /// Non-generic interface used for all parts of the API which don't require
    /// any type knowledge.
    /// </summary>
    public interface IMessage : IMessageLite
    {
        /// <summary>
        /// Returns the message's type's descriptor. This differs from the
        /// Descriptor property of each generated message class in that this
        /// method is an abstract method of IMessage whereas Descriptor is
        /// a static property of a specific class. They return the same thing.
        /// </summary>
        MessageDescriptor DescriptorForType { get; }

        /// <summary>
        /// Returns a collection of all the fields in this message which are set
        /// and their corresponding values.  A singular ("required" or "optional")
        /// field is set iff HasField() returns true for that field.  A "repeated"
        /// field is set iff GetRepeatedFieldSize() is greater than zero.  The
        /// values are exactly what would be returned by calling
        /// GetField(FieldDescriptor) for each field.  The map
        /// is guaranteed to be a sorted map, so iterating over it will return fields
        /// in order by field number. 
        /// </summary>
        IDictionary<FieldDescriptor, object> AllFields { get; }

        /// <summary>
        /// Returns true if the given field is set. This is exactly equivalent
        /// to calling the generated "Has" property corresponding to the field.
        /// </summary>
        /// <exception cref="ArgumentException">the field is a repeated field,
        /// or it's not a field of this type</exception>
        bool HasField(FieldDescriptor field);

        /// <summary>
        /// Obtains the value of the given field, or the default value if
        /// it isn't set. For value type fields, the boxed value is returned.
        /// For enum fields, the EnumValueDescriptor for the enum is returned.
        /// For embedded message fields, the sub-message
        /// is returned. For repeated fields, an IList&lt;T&gt; is returned.
        /// </summary>
        object this[FieldDescriptor field] { get; }

        /// <summary>
        /// Returns the number of elements of a repeated field. This is
        /// exactly equivalent to calling the generated "Count" property
        /// corresponding to the field.
        /// </summary>
        /// <exception cref="ArgumentException">the field is not a repeated field,
        /// or it's not a field of this type</exception>
        int GetRepeatedFieldCount(FieldDescriptor field);

        /// <summary>
        /// Gets an element of a repeated field. For value type fields 
        /// excluding enums, the boxed value is returned. For embedded
        /// message fields, the sub-message is returned. For enums, the
        /// relevant EnumValueDescriptor is returned.
        /// </summary>
        /// <exception cref="ArgumentException">the field is not a repeated field,
        /// or it's not a field of this type</exception>
        /// <exception cref="ArgumentOutOfRangeException">the index is out of
        /// range for the repeated field's value</exception>
        object this[FieldDescriptor field, int index] { get; }

        /// <summary>
        /// Returns the unknown fields for this message.
        /// </summary>
        UnknownFieldSet UnknownFields { get; }

        /// <summary>
        /// Returns true iff all required fields in the message and all embedded
        /// messages are set.
        /// </summary>
        new bool IsInitialized { get; }

        /// <summary>
        /// Serializes the message and writes it to the given output stream.
        /// This does not flush or close the stream.
        /// </summary>
        /// <remarks>
        /// Protocol Buffers are not self-delimiting. Therefore, if you write
        /// any more data to the stream after the message, you must somehow ensure
        /// that the parser on the receiving end does not interpret this as being
        /// part of the protocol message. One way of doing this is by writing the size
        /// of the message before the data, then making sure you limit the input to
        /// that size when receiving the data. Alternatively, use WriteDelimitedTo(Stream).
        /// </remarks>
        new void WriteTo(ICodedOutputStream output);

        /// <summary>
        /// Like WriteTo(Stream) but writes the size of the message as a varint before
        /// writing the data. This allows more data to be written to the stream after the
        /// message without the need to delimit the message data yourself. Use 
        /// IBuilder.MergeDelimitedFrom(Stream) or the static method
        /// YourMessageType.ParseDelimitedFrom(Stream) to parse messages written by this method.
        /// </summary>
        /// <param name="output"></param>
        new void WriteDelimitedTo(Stream output);

        /// <summary>
        /// Returns the number of bytes required to encode this message.
        /// The result is only computed on the first call and memoized after that.
        /// </summary>
        new int SerializedSize { get; }

        #region Comparison and hashing

        /// <summary>
        /// Compares the specified object with this message for equality.
        /// Returns true iff the given object is a message of the same type
        /// (as defined by DescriptorForType) and has identical values
        /// for all its fields.
        /// </summary>
        new bool Equals(object other);

        /// <summary>
        /// Returns the hash code value for this message.
        /// TODO(jonskeet): Specify the hash algorithm, but better than the Java one!
        /// </summary>
        new int GetHashCode();

        #endregion

        #region Convenience methods

        /// <summary>
        /// Converts the message to a string in protocol buffer text format.
        /// This is just a trivial wrapper around TextFormat.PrintToString.
        /// </summary>
        new string ToString();

        /// <summary>
        /// Serializes the message to a ByteString. This is a trivial wrapper
        /// around WriteTo(ICodedOutputStream).
        /// </summary>
        new ByteString ToByteString();

        /// <summary>
        /// Serializes the message to a byte array. This is a trivial wrapper
        /// around WriteTo(ICodedOutputStream).
        /// </summary>
        new byte[] ToByteArray();

        /// <summary>
        /// Serializes the message and writes it to the given stream.
        /// This is just a wrapper around WriteTo(ICodedOutputStream). This
        /// does not flush or close the stream.
        /// </summary>
        /// <param name="output"></param>
        new void WriteTo(Stream output);

        #endregion

        /// <summary>
        /// Creates a builder for the type, but in a weakly typed manner. This
        /// is typically implemented by strongly typed messages by just returning
        /// the result of CreateBuilderForType.
        /// </summary>
        new IBuilder WeakCreateBuilderForType();

        /// <summary>
        /// Creates a builder with the same contents as this message. This
        /// is typically implemented by strongly typed messages by just returning
        /// the result of ToBuilder.
        /// </summary>
        new IBuilder WeakToBuilder();

        new IMessage WeakDefaultInstanceForType { get; }
    }

    public interface IMessage<TMessage> : IMessage, IMessageLite<TMessage>
    {
        /// <summary>
        /// Returns an instance of this message type with all fields set to
        /// their default values. This may or may not be a singleton. This differs
        /// from the DefaultInstance property of each generated message class in that this
        /// method is an abstract method of IMessage whereas DefaultInstance is
        /// a static property of a specific class. They return the same thing.
        /// </summary>
        new TMessage DefaultInstanceForType { get; }
    }

    /// <summary>
    /// Type-safe interface for all generated messages to implement.
    /// </summary>
    public interface IMessage<TMessage, TBuilder> : IMessage<TMessage>, IMessageLite<TMessage, TBuilder>
        where TMessage : IMessage<TMessage, TBuilder>
        where TBuilder : IBuilder<TMessage, TBuilder>
    {
        #region Builders

        /// <summary>
        /// Constructs a new builder for a message of the same type as this message.
        /// </summary>
        new TBuilder CreateBuilderForType();

        /// <summary>
        /// Creates a builder with the same contents as this current instance.
        /// This is typically implemented by strongly typed messages by just
        /// returning the result of ToBuilder().
        /// </summary>
        new TBuilder ToBuilder();

        #endregion
    }
}