1#region Copyright notice and license
2// Protocol Buffers - Google's data interchange format
3// Copyright 2015 Google Inc.  All rights reserved.
4// https://developers.google.com/protocol-buffers/
5//
6// Redistribution and use in source and binary forms, with or without
7// modification, are permitted provided that the following conditions are
8// met:
9//
10//     * Redistributions of source code must retain the above copyright
11// notice, this list of conditions and the following disclaimer.
12//     * Redistributions in binary form must reproduce the above
13// copyright notice, this list of conditions and the following disclaimer
14// in the documentation and/or other materials provided with the
15// distribution.
16//     * Neither the name of Google Inc. nor the names of its
17// contributors may be used to endorse or promote products derived from
18// this software without specific prior written permission.
19//
20// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31#endregion
32
33using System;
34using System.IO;
35
36namespace Google.Protobuf
37{
38    /// <summary>
39    /// A general message parser, typically used by reflection-based code as all the methods
40    /// return simple <see cref="IMessage"/>.
41    /// </summary>
42    public class MessageParser
43    {
44        private Func<IMessage> factory;
45
46        internal MessageParser(Func<IMessage> factory)
47        {
48            this.factory = factory;
49        }
50
51        /// <summary>
52        /// Creates a template instance ready for population.
53        /// </summary>
54        /// <returns>An empty message.</returns>
55        internal IMessage CreateTemplate()
56        {
57            return factory();
58        }
59
60        /// <summary>
61        /// Parses a message from a byte array.
62        /// </summary>
63        /// <param name="data">The byte array containing the message. Must not be null.</param>
64        /// <returns>The newly parsed message.</returns>
65        public IMessage ParseFrom(byte[] data)
66        {
67            ProtoPreconditions.CheckNotNull(data, "data");
68            IMessage message = factory();
69            message.MergeFrom(data);
70            return message;
71        }
72
73        /// <summary>
74        /// Parses a message from the given byte string.
75        /// </summary>
76        /// <param name="data">The data to parse.</param>
77        /// <returns>The parsed message.</returns>
78        public IMessage ParseFrom(ByteString data)
79        {
80            ProtoPreconditions.CheckNotNull(data, "data");
81            IMessage message = factory();
82            message.MergeFrom(data);
83            return message;
84        }
85
86        /// <summary>
87        /// Parses a message from the given stream.
88        /// </summary>
89        /// <param name="input">The stream to parse.</param>
90        /// <returns>The parsed message.</returns>
91        public IMessage ParseFrom(Stream input)
92        {
93            IMessage message = factory();
94            message.MergeFrom(input);
95            return message;
96        }
97
98        /// <summary>
99        /// Parses a length-delimited message from the given stream.
100        /// </summary>
101        /// <remarks>
102        /// The stream is expected to contain a length and then the data. Only the amount of data
103        /// specified by the length will be consumed.
104        /// </remarks>
105        /// <param name="input">The stream to parse.</param>
106        /// <returns>The parsed message.</returns>
107        public IMessage ParseDelimitedFrom(Stream input)
108        {
109            IMessage message = factory();
110            message.MergeDelimitedFrom(input);
111            return message;
112        }
113
114        /// <summary>
115        /// Parses a message from the given coded input stream.
116        /// </summary>
117        /// <param name="input">The stream to parse.</param>
118        /// <returns>The parsed message.</returns>
119        public IMessage ParseFrom(CodedInputStream input)
120        {
121            IMessage message = factory();
122            message.MergeFrom(input);
123            return message;
124        }
125
126        /// <summary>
127        /// Parses a message from the given JSON.
128        /// </summary>
129        /// <param name="json">The JSON to parse.</param>
130        /// <returns>The parsed message.</returns>
131        /// <exception cref="InvalidJsonException">The JSON does not comply with RFC 7159</exception>
132        /// <exception cref="InvalidProtocolBufferException">The JSON does not represent a Protocol Buffers message correctly</exception>
133        public IMessage ParseJson(string json)
134        {
135            IMessage message = factory();
136            JsonParser.Default.Merge(message, json);
137            return message;
138        }
139    }
140
141    /// <summary>
142    /// A parser for a specific message type.
143    /// </summary>
144    /// <remarks>
145    /// <p>
146    /// This delegates most behavior to the
147    /// <see cref="IMessage.MergeFrom"/> implementation within the original type, but
148    /// provides convenient overloads to parse from a variety of sources.
149    /// </p>
150    /// <p>
151    /// Most applications will never need to create their own instances of this type;
152    /// instead, use the static <c>Parser</c> property of a generated message type to obtain a
153    /// parser for that type.
154    /// </p>
155    /// </remarks>
156    /// <typeparam name="T">The type of message to be parsed.</typeparam>
157    public sealed class MessageParser<T> : MessageParser where T : IMessage<T>
158    {
159        // Implementation note: all the methods here *could* just delegate up to the base class and cast the result.
160        // The current implementation avoids a virtual method call and a cast, which *may* be significant in some cases.
161        // Benchmarking work is required to measure the significance - but it's only a few lines of code in any case.
162        // The API wouldn't change anyway - just the implementation - so this work can be deferred.
163        private readonly Func<T> factory;
164
165        /// <summary>
166        /// Creates a new parser.
167        /// </summary>
168        /// <remarks>
169        /// The factory method is effectively an optimization over using a generic constraint
170        /// to require a parameterless constructor: delegates are significantly faster to execute.
171        /// </remarks>
172        /// <param name="factory">Function to invoke when a new, empty message is required.</param>
173        public MessageParser(Func<T> factory) : base(() => factory())
174        {
175            this.factory = factory;
176        }
177
178        /// <summary>
179        /// Creates a template instance ready for population.
180        /// </summary>
181        /// <returns>An empty message.</returns>
182        internal new T CreateTemplate()
183        {
184            return factory();
185        }
186
187        /// <summary>
188        /// Parses a message from a byte array.
189        /// </summary>
190        /// <param name="data">The byte array containing the message. Must not be null.</param>
191        /// <returns>The newly parsed message.</returns>
192        public new T ParseFrom(byte[] data)
193        {
194            ProtoPreconditions.CheckNotNull(data, "data");
195            T message = factory();
196            message.MergeFrom(data);
197            return message;
198        }
199
200        /// <summary>
201        /// Parses a message from the given byte string.
202        /// </summary>
203        /// <param name="data">The data to parse.</param>
204        /// <returns>The parsed message.</returns>
205        public new T ParseFrom(ByteString data)
206        {
207            ProtoPreconditions.CheckNotNull(data, "data");
208            T message = factory();
209            message.MergeFrom(data);
210            return message;
211        }
212
213        /// <summary>
214        /// Parses a message from the given stream.
215        /// </summary>
216        /// <param name="input">The stream to parse.</param>
217        /// <returns>The parsed message.</returns>
218        public new T ParseFrom(Stream input)
219        {
220            T message = factory();
221            message.MergeFrom(input);
222            return message;
223        }
224
225        /// <summary>
226        /// Parses a length-delimited message from the given stream.
227        /// </summary>
228        /// <remarks>
229        /// The stream is expected to contain a length and then the data. Only the amount of data
230        /// specified by the length will be consumed.
231        /// </remarks>
232        /// <param name="input">The stream to parse.</param>
233        /// <returns>The parsed message.</returns>
234        public new T ParseDelimitedFrom(Stream input)
235        {
236            T message = factory();
237            message.MergeDelimitedFrom(input);
238            return message;
239        }
240
241        /// <summary>
242        /// Parses a message from the given coded input stream.
243        /// </summary>
244        /// <param name="input">The stream to parse.</param>
245        /// <returns>The parsed message.</returns>
246        public new T ParseFrom(CodedInputStream input)
247        {
248            T message = factory();
249            message.MergeFrom(input);
250            return message;
251        }
252
253        /// <summary>
254        /// Parses a message from the given JSON.
255        /// </summary>
256        /// <param name="json">The JSON to parse.</param>
257        /// <returns>The parsed message.</returns>
258        /// <exception cref="InvalidJsonException">The JSON does not comply with RFC 7159</exception>
259        /// <exception cref="InvalidProtocolBufferException">The JSON does not represent a Protocol Buffers message correctly</exception>
260        public new T ParseJson(string json)
261        {
262            T message = factory();
263            JsonParser.Default.Merge(message, json);
264            return message;
265        }
266    }
267}
268