Merge pull request #2 from cockroachdb/omitempty

add omitempty option

Makefile

@@ -140,6 +140,7 @@ regenerate:
 	make -C test/issue620 regenerate
 	make -C test/protobuffer regenerate
 	make -C test/issue630 regenerate
+	make -C test/omitempty regenerate
 
 	make gofmt
 

gogoproto/gogo.proto

@@ -141,4 +141,11 @@ extend google.protobuf.FieldOptions {
 	optional bool stdduration = 65011;
 	optional bool wktpointer = 65012;
 
+
+	// omitempty is used to skip marshaling non-nullable fields which are empty
+	// (unset). The field's type must implement an `.Empty()` method which will be
+	// consulted prior to marshaling.
+	//
+	// Added by cockroach.
+	optional bool omitempty = 65013;
 }

gogoproto/helper.go

@@ -39,6 +39,10 @@ func IsNullable(field *google_protobuf.FieldDescriptorProto) bool {
 	return proto.GetBoolExtension(field.Options, E_Nullable, true)
 }
 
+func IsOmitEmpty(field *google_protobuf.FieldDescriptorProto) bool {
+	return proto.GetBoolExtension(field.Options, E_Omitempty, false)
+}
+
 func IsStdTime(field *google_protobuf.FieldDescriptorProto) bool {
 	return proto.GetBoolExtension(field.Options, E_Stdtime, false)
 }

plugin/marshalto/marshalto.go

@@ -338,6 +338,7 @@ func (p *marshalto) generateField(proto3 bool, numGen NumGen, file *generator.Fi
 
 	protoSizer := gogoproto.IsProtoSizer(file.FileDescriptorProto, message.DescriptorProto)
 	doNilCheck := gogoproto.NeedsNilCheck(proto3, field)
+	omitEmpty := gogoproto.IsOmitEmpty(field)
 	if required && nullable {
 		p.P(`if m.`, fieldname, `== nil {`)
 		p.In()
@@ -354,6 +355,10 @@ func (p *marshalto) generateField(proto3 bool, numGen NumGen, file *generator.Fi
 	} else if doNilCheck {
 		p.P(`if m.`, fieldname, ` != nil {`)
 		p.In()
+	} else if omitEmpty {
+		p.P(`// Field has gogoproto.omitempty set.`)
+		p.P(`if !m.`, fieldname, `.Empty() {`)
+		p.In()
 	}
 	packed := field.IsPacked() || (proto3 && field.IsPacked3())
 	wireType := field.WireType()
@@ -689,6 +694,7 @@ func (p *marshalto) generateField(proto3 bool, numGen NumGen, file *generator.Fi
 			nullableMsg := nullable && (m.ValueField.GetType() == descriptor.FieldDescriptorProto_TYPE_MESSAGE ||
 				gogoproto.IsCustomType(field) && m.ValueField.IsBytes())
 			plainBytes := m.ValueField.IsBytes() && !gogoproto.IsCustomType(field)
+			omitEmpty := gogoproto.IsOmitEmpty(field)
 			if nullableMsg {
 				p.P(`if `, accessor, ` != nil { `)
 				p.In()
@@ -699,10 +705,14 @@ func (p *marshalto) generateField(proto3 bool, numGen NumGen, file *generator.Fi
 					p.P(`if `, accessor, ` != nil {`)
 				}
 				p.In()
+			} else if omitEmpty {
+				p.P(`// Field has gogoproto.omitempty set.`)
+				p.P(`if !`, accessor, `.Empty() {`)
+				p.In()
 			}
 			p.mapField(numGen, field, m.ValueAliasField, accessor, protoSizer)
 			p.encodeKey(2, wireToType(valuewire))
-			if nullableMsg || plainBytes {
+			if nullableMsg || plainBytes || omitEmpty {
 				p.Out()
 				p.P(`}`)
 			}
@@ -877,7 +887,7 @@ func (p *marshalto) generateField(proto3 bool, numGen NumGen, file *generator.Fi
 	default:
 		panic("not implemented")
 	}
-	if (required && nullable) || repeated || doNilCheck {
+	if (required && nullable) || repeated || doNilCheck || omitEmpty {
 		p.Out()
 		p.P(`}`)
 	}

protoc-gen-gogo/generator/helper.go

@@ -284,6 +284,11 @@ func (g *Generator) GetMapValueField(field, valField *descriptor.FieldDescriptor
 	if err := proto.SetExtension(valField.Options, gogoproto.E_Nullable, &nullable); err != nil {
 		g.Fail(err.Error())
 	}
+
+	omitEmpty := gogoproto.IsOmitEmpty(field)
+	if err := proto.SetExtension(valField.Options, gogoproto.E_Omitempty, &omitEmpty); err != nil {
+		g.Fail(err.Error())
+	}
 	return valField
 }
 

test/omitempty/Makefile

@@ -0,0 +1,32 @@
+# Protocol Buffers for Go with Gadgets
+#
+# Copyright (c) 2015, The GoGo Authors. All rights reserved.
+# http://github.com/gogo/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.
+#
+# 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.
+
+regenerate:
+	go install github.com/gogo/protobuf/protoc-gen-combo
+	go install github.com/gogo/protobuf/protoc-gen-gogo
+	protoc-gen-combo --gogo_out=. --version="3.0.0" --proto_path=../../protobuf/:../../../../../:. omitempty.proto

test/omitempty/combos/both/mymethod.go

@@ -0,0 +1,5 @@
+package omitempty
+
+func (o *OmitEmpty_Inner) Empty() bool {
+	return o.Foo == 0
+}