Implement JSON parsing in C#.

This includes all the well-known types except Any.
Some aspects are likely to require further work when the details of the JSON parsing expectations are hammered out in more detail. Some of these have "ignored" tests already.

Note that the choice *not* to use Json.NET was made for two reasons:
- Going from 0 dependencies to 1 dependency is a big hit, and there's not much benefit here
- Json.NET parses more leniently than we'd want; accommodating that would be nearly as much work as writing the tokenizer
This only really affects the JsonTokenizer, which could be replaced by Json.NET. The JsonParser code would be about the same length with Json.NET... but I wouldn't be as confident in it.

1 files changed, 166 insertions, 0 deletions

diff --git a/csharp/src/Google.Protobuf/JsonToken.cs b/csharp/src/Google.Protobuf/JsonToken.cs
new file mode 100644
index 00000000..6c0138cc
--- /dev/null
+++ b/csharp/src/Google.Protobuf/JsonToken.cs
@@ -0,0 +1,166 @@
+#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 System;
+
+namespace Google.Protobuf
+{
+    internal sealed class JsonToken : IEquatable<JsonToken>
+    {
+        // Tokens with no value can be reused.
+        private static readonly JsonToken _true = new JsonToken(TokenType.True);
+        private static readonly JsonToken _false = new JsonToken(TokenType.False);
+        private static readonly JsonToken _null = new JsonToken(TokenType.Null);
+        private static readonly JsonToken startObject = new JsonToken(TokenType.StartObject);
+        private static readonly JsonToken endObject = new JsonToken(TokenType.EndObject);
+        private static readonly JsonToken startArray = new JsonToken(TokenType.StartArray);
+        private static readonly JsonToken endArray = new JsonToken(TokenType.EndArray);
+        private static readonly JsonToken endDocument = new JsonToken(TokenType.EndDocument);
+
+        internal static JsonToken Null { get { return _null; } }
+        internal static JsonToken False { get { return _false; } }
+        internal static JsonToken True { get { return _true; } }
+        internal static JsonToken StartObject{ get { return startObject; } }
+        internal static JsonToken EndObject { get { return endObject; } }
+        internal static JsonToken StartArray { get { return startArray; } }
+        internal static JsonToken EndArray { get { return endArray; } }
+        internal static JsonToken EndDocument { get { return endDocument; } }
+
+        internal static JsonToken Name(string name)
+        {
+            return new JsonToken(TokenType.Name, stringValue: name);
+        }
+
+        internal static JsonToken Value(string value)
+        {
+            return new JsonToken(TokenType.StringValue, stringValue: value);
+        }
+
+        internal static JsonToken Value(double value)
+        {
+            return new JsonToken(TokenType.Number, numberValue: value);
+        }
+
+        internal enum TokenType
+        {
+            Null,
+            False,
+            True,
+            StringValue,
+            Number,
+            Name,
+            StartObject,
+            EndObject,
+            StartArray,
+            EndArray,
+            EndDocument
+        }
+
+        // A value is a string, number, array, object, null, true or false
+        // Arrays and objects have start/end
+        // A document consists of a value
+        // Objects are name/value sequences.
+
+        private readonly TokenType type;
+        private readonly string stringValue;
+        private readonly double numberValue;
+
+        internal TokenType Type { get { return type; } }
+        internal string StringValue { get { return stringValue; } }
+        internal double NumberValue { get { return numberValue; } }
+
+        private JsonToken(TokenType type, string stringValue = null, double numberValue = 0)
+        {
+            this.type = type;
+            this.stringValue = stringValue;
+            this.numberValue = numberValue;
+        }
+
+        public override bool Equals(object obj)
+        {
+            return Equals(obj as JsonToken);
+        }
+
+        public override int GetHashCode()
+        {
+            unchecked
+            {
+                int hash = 17;
+                hash = hash * 31 + (int) type;
+                hash = hash * 31 + stringValue == null ? 0 : stringValue.GetHashCode();
+                hash = hash * 31 + numberValue.GetHashCode();
+                return hash;
+            }
+        }
+
+        public override string ToString()
+        {
+            switch (type)
+            {
+                case TokenType.Null:
+                    return "null";
+                case TokenType.True:
+                    return "true";
+                case TokenType.False:
+                    return "false";
+                case TokenType.Name:
+                    return "name (" + stringValue + ")";
+                case TokenType.StringValue:
+                    return "value (" + stringValue + ")";
+                case TokenType.Number:
+                    return "number (" + numberValue + ")";
+                case TokenType.StartObject:
+                    return "start-object";
+                case TokenType.EndObject:
+                    return "end-object";
+                case TokenType.StartArray:
+                    return "start-array";
+                case TokenType.EndArray:
+                    return "end-array";
+                case TokenType.EndDocument:
+                    return "end-document";
+                default:
+                    throw new InvalidOperationException("Token is of unknown type " + type);
+            }
+        }
+
+        public bool Equals(JsonToken other)
+        {
+            if (ReferenceEquals(other, null))
+            {
+                return false;
+            }
+            // Note use of other.numberValue.Equals rather than ==, so that NaN compares appropriately.
+            return other.type == type && other.stringValue == stringValue && other.numberValue.Equals(numberValue);
+        }
+    }
+}