Merge pull request protocolbuffers#1301 from avgweb/master

Replace StringBuilder with TextWriter in JsonFormatter

Author: jskeet

csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs

@@ -710,5 +710,14 @@ public void CustomDiagnosticMessage_Nested()
             Assert.AreEqual("{ \"singleForeignMessage\": { \"c\": 16, \"@cInHex\": \"10\" } }", message.ToString());
             Assert.AreEqual("{ \"singleForeignMessage\": { \"c\": 16 } }", JsonFormatter.Default.Format(message));
         }
+
+        [Test]
+        public void CustomDiagnosticMessage_DirectToTextWriterCall()
+        {
+            var message = new ForeignMessage { C = 31 };
+            var writer = new StringWriter();
+            JsonFormatter.Default.Format(message, writer);
+            Assert.AreEqual("{ \"c\": 31 }", writer.ToString());
+        }
     }
 }

csharp/src/Google.Protobuf/Collections/MapField.cs

@@ -34,6 +34,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Text;
 using Google.Protobuf.Compatibility;
@@ -474,9 +475,9 @@ public int CalculateSize(Codec codec)
         /// </summary>
         public override string ToString()
         {
-            var builder = new StringBuilder();
-            JsonFormatter.Default.WriteDictionary(builder, this);
-            return builder.ToString();
+            var writer = new StringWriter();
+            JsonFormatter.Default.WriteDictionary(writer, this);
+            return writer.ToString();
         }
 
         #region IDictionary explicit interface implementation

csharp/src/Google.Protobuf/Collections/RepeatedField.cs

@@ -33,6 +33,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.IO;
 using System.Text;
 
 namespace Google.Protobuf.Collections
@@ -474,9 +475,9 @@ public void RemoveAt(int index)
         /// </summary>
         public override string ToString()
         {
-            var builder = new StringBuilder();
-            JsonFormatter.Default.WriteList(builder, this);
-            return builder.ToString();
+            var writer = new StringWriter();
+            JsonFormatter.Default.WriteList(writer, this);
+            return writer.ToString();
         }
 
         /// <summary>