First pass at implementation and testing of reusable builders.

1 files changed, 43 insertions, 12 deletions

diff --git a/src/ProtoGen/MessageGenerator.cs b/src/ProtoGen/MessageGenerator.cs
index 01d47ce2..f191da4f 100644
--- a/src/ProtoGen/MessageGenerator.cs
+++ b/src/ProtoGen/MessageGenerator.cs
@@ -551,7 +551,7 @@ namespace Google.ProtocolBuffers.ProtoGen
             writer.WriteLine("public override Builder ToBuilder() { return CreateBuilder(this); }");

             writer.WriteLine("public override Builder CreateBuilderForType() { return new Builder(); }");

             writer.WriteLine("public static Builder CreateBuilder({0} prototype) {{", ClassName);

-            writer.WriteLine("  return (Builder) new Builder().MergeFrom(prototype);");

+            writer.WriteLine("  return new Builder(prototype);");

             writer.WriteLine("}");

             writer.WriteLine();

             writer.WriteLine("[global::System.Diagnostics.DebuggerNonUserCodeAttribute()]");

@@ -582,21 +582,52 @@ namespace Google.ProtocolBuffers.ProtoGen
 

         private void GenerateCommonBuilderMethods(TextGenerator writer)

         {

-            writer.WriteLine("public Builder() {{}}", ClassAccessLevel);

+            //default constructor

+            writer.WriteLine("public Builder() {");

+            //Durring static initialization of message, DefaultInstance is expected to return null.

+            writer.WriteLine("  result = DefaultInstance ?? new {0}();", ClassName);

+            writer.WriteLine("  builderIsReadOnly = result == DefaultInstance;");

+            writer.WriteLine("}");

+            //clone constructor

+            writer.WriteLine("internal Builder({0} cloneFrom) {{", ClassName);

+            writer.WriteLine("  result = cloneFrom;");

+            writer.WriteLine("  builderIsReadOnly = true;");

+            writer.WriteLine("}");

+            writer.WriteLine();

+            writer.WriteLine("bool builderIsReadOnly;");

+            writer.WriteLine("{0} result;", ClassName);

+            writer.WriteLine();

+            writer.WriteLine("private {0} PrepareBuilder() {{", ClassName);

+            writer.WriteLine("  if (builderIsReadOnly) {");

+            writer.WriteLine("    {0} original = result;", ClassName);

+            writer.WriteLine("    result = new {0}();", ClassName);

+            writer.WriteLine("    builderIsReadOnly = false;");

+            writer.WriteLine("    MergeFrom(original);");

+            writer.WriteLine("  }");

+            writer.WriteLine("  return result;");

+            writer.WriteLine("}");

             writer.WriteLine();

-            writer.WriteLine("{0} result = new {0}();", ClassName);

+            writer.WriteLine("public override bool IsInitialized {");

+            writer.WriteLine("  get { return result.IsInitialized; }");

+            writer.WriteLine("}");

             writer.WriteLine();

             writer.WriteLine("protected override {0} MessageBeingBuilt {{", ClassName);

-            writer.WriteLine("  get { return result; }");

+            writer.WriteLine("  get { return PrepareBuilder(); }");

             writer.WriteLine("}");

             writer.WriteLine();

+            //Not actually expecting that DefaultInstance would ever be null here; however, we will ensure it does not break

             writer.WriteLine("public override Builder Clear() {");

-            writer.WriteLine("  result = new {0}();", ClassName);

+            writer.WriteLine("  result = DefaultInstance ?? new {0}();", ClassName);

+            writer.WriteLine("  builderIsReadOnly = true;");

             writer.WriteLine("  return this;");

             writer.WriteLine("}");

             writer.WriteLine();

             writer.WriteLine("public override Builder Clone() {");

-            writer.WriteLine("  return new Builder().MergeFrom(result);");

+            writer.WriteLine("  if (builderIsReadOnly) {");

+            writer.WriteLine("    return new Builder(result);");

+            writer.WriteLine("  } else {");

+            writer.WriteLine("    return new Builder().MergeFrom(result);");

+            writer.WriteLine("  }");

             writer.WriteLine("}");

             writer.WriteLine();

             if (!UseLiteRuntime)

@@ -613,17 +644,15 @@ namespace Google.ProtocolBuffers.ProtoGen
 

             writer.WriteLine("public override {0} BuildPartial() {{", ClassName);

             writer.Indent();

-            writer.WriteLine("if (result == null) {");

-            writer.WriteLine(

-                "  throw new global::System.InvalidOperationException(\"build() has already been called on this Builder\");");

+            writer.WriteLine("if (builderIsReadOnly) {");

+            writer.WriteLine("  return result;");

             writer.WriteLine("}");

             foreach (FieldDescriptor field in Descriptor.Fields)

             {

                 CreateFieldGenerator(field).GenerateBuildingCode(writer);

             }

-            writer.WriteLine("{0} returnMe = result;", ClassName);

-            writer.WriteLine("result = null;");

-            writer.WriteLine("return returnMe;");

+            writer.WriteLine("builderIsReadOnly = true;");

+            writer.WriteLine("return result;");

             writer.Outdent();

             writer.WriteLine("}");

             writer.WriteLine();

@@ -644,6 +673,7 @@ namespace Google.ProtocolBuffers.ProtoGen
                 // fields are set so we can skip the merge.

                 writer.Indent();

                 writer.WriteLine("if (other == {0}.DefaultInstance) return this;", FullClassName);

+                writer.WriteLine("PrepareBuilder();");

                 foreach (FieldDescriptor field in Descriptor.Fields)

                 {

                     CreateFieldGenerator(field).GenerateMergingCode(writer);

@@ -676,6 +706,7 @@ namespace Google.ProtocolBuffers.ProtoGen
             writer.WriteLine(

                 "public override Builder MergeFrom(pb::ICodedInputStream input, pb::ExtensionRegistry extensionRegistry) {");

             writer.Indent();

+            writer.WriteLine("PrepareBuilder();");

             if (!UseLiteRuntime)

             {

                 writer.WriteLine("pb::UnknownFieldSet.Builder unknownFields = null;");