Go support for protocol buffers.

Consists of a compiler plugin and the support library, all written in Go.

This is a complete implementation except for:
  - Extensions in the plugin
    - coming soon
    - support is already in the library
  - Services (RPC)
    - needs an external definition to honor before supporting.
  - Insertion points in the plugin
    - may come

R=rsc, dsymonds1, ken2
CC=golang-dev
http://codereview.appspot.com/676041
diff --git a/compiler/plugin/Makefile b/compiler/plugin/Makefile
new file mode 100644
index 0000000..08be77f
--- /dev/null
+++ b/compiler/plugin/Makefile
@@ -0,0 +1,54 @@
+# Go support for Protocol Buffers - Google's data interchange format
+#
+# Copyright 2010 Google Inc.  All rights reserved.
+# http://code.google.com/p/goprotobuf/
+#
+# 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.
+
+include $(GOROOT)/src/Make.$(GOARCH)
+
+TARG=goprotobuf.googlecode.com/hg/compiler/plugin
+GOFILES=\
+	plugin.pb.go\
+
+include $(GOROOT)/src/Make.pkg
+
+# Not stored here, but plugin.proto is in http://code.google.com/p/protobuf
+# at protobuf-2.3.0/src/google/protobuf/compiler/plugin.proto
+# Also we need to fix an import.
+regenerate:
+	echo WARNING! THIS RULE IS PROBABLY NOT RIGHT FOR YOUR INSTALLATION
+	cd $(HOME)/protobuf-2.3.0/src && \
+	protoc --go_out=. ./google/protobuf/compiler/plugin.proto && \
+	cat ./google/protobuf/compiler/plugin.pb.go | \
+		sed '/^import/s;google/protobuf/descriptor.pb;goprotobuf.googlecode.com/hg/compiler/descriptor;' >$(GOROOT)/src/pkg/goprotobuf.googlecode.com/hg/compiler/plugin/plugin.pb.go
+
+restore:
+	cp plugin.pb.golden plugin.pb.go
+
+preserve:
+	cp plugin.pb.go plugin.pb.golden
diff --git a/compiler/plugin/plugin.pb.go b/compiler/plugin/plugin.pb.go
new file mode 100644
index 0000000..1c11686
--- /dev/null
+++ b/compiler/plugin/plugin.pb.go
@@ -0,0 +1,47 @@
+// Code generated by protoc-gen-go from "google/protobuf/compiler/plugin.proto"
+// DO NOT EDIT!
+
+package google_protobuf_compiler
+
+import google_protobuf "goprotobuf.googlecode.com/hg/compiler/descriptor"
+
+type CodeGeneratorRequest struct {
+	FileToGenerate	[]string	"PB(bytes,1,rep,name=file_to_generate)"
+	Parameter	*string	"PB(bytes,2,opt,name=parameter)"
+	ProtoFile	[]*google_protobuf.FileDescriptorProto	"PB(bytes,15,rep,name=proto_file)"
+	XXX_unrecognized	[]byte
+}
+func (this *CodeGeneratorRequest) Reset() {
+	*this = CodeGeneratorRequest{}
+}
+func NewCodeGeneratorRequest() *CodeGeneratorRequest {
+	return new(CodeGeneratorRequest)
+}
+
+type CodeGeneratorResponse struct {
+	Error	*string	"PB(bytes,1,opt,name=error)"
+	File	[]*CodeGeneratorResponse_File	"PB(bytes,15,rep,name=file)"
+	XXX_unrecognized	[]byte
+}
+func (this *CodeGeneratorResponse) Reset() {
+	*this = CodeGeneratorResponse{}
+}
+func NewCodeGeneratorResponse() *CodeGeneratorResponse {
+	return new(CodeGeneratorResponse)
+}
+
+type CodeGeneratorResponse_File struct {
+	Name	*string	"PB(bytes,1,opt,name=name)"
+	InsertionPoint	*string	"PB(bytes,2,opt,name=insertion_point)"
+	Content	*string	"PB(bytes,15,opt,name=content)"
+	XXX_unrecognized	[]byte
+}
+func (this *CodeGeneratorResponse_File) Reset() {
+	*this = CodeGeneratorResponse_File{}
+}
+func NewCodeGeneratorResponse_File() *CodeGeneratorResponse_File {
+	return new(CodeGeneratorResponse_File)
+}
+
+func init() {
+}
diff --git a/compiler/plugin/plugin.pb.golden b/compiler/plugin/plugin.pb.golden
new file mode 100644
index 0000000..1c11686
--- /dev/null
+++ b/compiler/plugin/plugin.pb.golden
@@ -0,0 +1,47 @@
+// Code generated by protoc-gen-go from "google/protobuf/compiler/plugin.proto"
+// DO NOT EDIT!
+
+package google_protobuf_compiler
+
+import google_protobuf "goprotobuf.googlecode.com/hg/compiler/descriptor"
+
+type CodeGeneratorRequest struct {
+	FileToGenerate	[]string	"PB(bytes,1,rep,name=file_to_generate)"
+	Parameter	*string	"PB(bytes,2,opt,name=parameter)"
+	ProtoFile	[]*google_protobuf.FileDescriptorProto	"PB(bytes,15,rep,name=proto_file)"
+	XXX_unrecognized	[]byte
+}
+func (this *CodeGeneratorRequest) Reset() {
+	*this = CodeGeneratorRequest{}
+}
+func NewCodeGeneratorRequest() *CodeGeneratorRequest {
+	return new(CodeGeneratorRequest)
+}
+
+type CodeGeneratorResponse struct {
+	Error	*string	"PB(bytes,1,opt,name=error)"
+	File	[]*CodeGeneratorResponse_File	"PB(bytes,15,rep,name=file)"
+	XXX_unrecognized	[]byte
+}
+func (this *CodeGeneratorResponse) Reset() {
+	*this = CodeGeneratorResponse{}
+}
+func NewCodeGeneratorResponse() *CodeGeneratorResponse {
+	return new(CodeGeneratorResponse)
+}
+
+type CodeGeneratorResponse_File struct {
+	Name	*string	"PB(bytes,1,opt,name=name)"
+	InsertionPoint	*string	"PB(bytes,2,opt,name=insertion_point)"
+	Content	*string	"PB(bytes,15,opt,name=content)"
+	XXX_unrecognized	[]byte
+}
+func (this *CodeGeneratorResponse_File) Reset() {
+	*this = CodeGeneratorResponse_File{}
+}
+func NewCodeGeneratorResponse_File() *CodeGeneratorResponse_File {
+	return new(CodeGeneratorResponse_File)
+}
+
+func init() {
+}