Skeleton for proto_zero_plugin.

components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc

Index: components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc
diff --git a/components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc b/components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..28fc99771588f5ff1b8ef90af9da552db8f86662
--- /dev/null
+++ b/components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc
@@ -0,0 +1,103 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "proto_zero_generator.h"
+
+#include <memory>
+#include <string>
+
+#include "third_party/protobuf/src/google/protobuf/descriptor.h"
+#include "third_party/protobuf/src/google/protobuf/io/printer.h"
+#include "third_party/protobuf/src/google/protobuf/io/zero_copy_stream.h"
+#include "third_party/protobuf/src/google/protobuf/stubs/strutil.h"
+
+namespace tracing {
+namespace proto {
+
+using google::protobuf::FileDescriptor;
+using google::protobuf::StripSuffixString;
+using google::protobuf::compiler::GeneratorContext;
+using google::protobuf::io::Printer;
+using google::protobuf::io::ZeroCopyOutputStream;
+
+namespace {
+
+class GeneratorJob {
+ public:
+  GeneratorJob(const FileDescriptor *file,
+               Printer* stub_h_printer,
+               Printer* stub_cc_printer)
+    : file_(file),
+      stub_h_(stub_h_printer),
+      stub_cc_(stub_cc_printer) {}
+
+  bool GenerateStubs() {
+    stub_h_->Print(
+        "// Autogenerated. DO NOT EDIT.\n"
+        "// Generated by: //components/tracing/proto_zero_plugin.\n\n"
+        "// Package: $package$\n",
+        "package", file_->package());
+    stub_cc_->Print(
+        "// Autogenerated. DO NOT EDIT.\n"
+        "// Generated by: //components/tracing/proto_zero_plugin.\n\n"
+        "// This file intentionally left blank.\n");
+    // TODO(kraynov) Implement in the next CL (crbug.com/608721).
+    return true;
+  }
+
+  // If generator fails to produce stubs for a particular proto definitions
+  // it finishes with undefined output and writes the first error occured.
+  const std::string& GetFirstError() const {
+    return error_;
+  }
+
+ private:
+  // Only the first error will be recorded.
+  void Abort(const std::string& reason) {
+    if (error_.empty()) {
+      error_ = reason;
+    }
+  }
+
+  const FileDescriptor* const file_;
+  Printer* const stub_h_;
+  Printer* const stub_cc_;
+  std::string error_;
+};
+
+}  // namespace
+
+ProtoZeroGenerator::ProtoZeroGenerator() {
+}
+
+ProtoZeroGenerator::~ProtoZeroGenerator() {
+}
+
+bool ProtoZeroGenerator::Generate(const FileDescriptor* file,
+                                  const std::string& options,
+                                  GeneratorContext* context,
+                                  std::string* error) const {
+
+  const std::string proto_stubs_name =
+      StripSuffixString(file->name(), ".proto") + ".pbzero";
+
+  const std::unique_ptr<ZeroCopyOutputStream> stub_h_file_stream(
+      context->Open(proto_stubs_name + ".h"));
+  const std::unique_ptr<ZeroCopyOutputStream> stub_cc_file_stream(
+      context->Open(proto_stubs_name + ".cc"));
+
+  // Variables are delimited by $.
+  Printer stub_h_printer(stub_h_file_stream.get(), '$');
+  Printer stub_cc_printer(stub_cc_file_stream.get(), '$');
+
+  GeneratorJob job(file, &stub_h_printer, &stub_cc_printer);
+  if (!job.GenerateStubs()) {
+    *error = job.GetFirstError();
+    return false;
+  }
+  return true;
+}
+
+}  // namespace proto
+}  // namespace tracing