add external dependencies in a pre-built way to avoid incompatibilities

external/include/google/protobuf/compiler/plugin.h

@@ -0,0 +1,94 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// 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.
+
+// Author: kenton@google.com (Kenton Varda)
+//
+// Front-end for protoc code generator plugins written in C++.
+//
+// To implement a protoc plugin in C++, simply write an implementation of
+// CodeGenerator, then create a main() function like:
+//   int main(int argc, char* argv[]) {
+//     MyCodeGenerator generator;
+//     return google::protobuf::compiler::PluginMain(argc, argv, &generator);
+//   }
+// You must link your plugin against libprotobuf and libprotoc.
+//
+// The core part of PluginMain is to invoke the given CodeGenerator on a
+// CodeGeneratorRequest to generate a CodeGeneratorResponse. This part is
+// abstracted out and made into function GenerateCode so that it can be reused,
+// for example, to implement a variant of PluginMain that does some
+// preprocessing on the input CodeGeneratorRequest before feeding the request
+// to the given code generator.
+//
+// To get protoc to use the plugin, do one of the following:
+// * Place the plugin binary somewhere in the PATH and give it the name
+//   "protoc-gen-NAME" (replacing "NAME" with the name of your plugin).  If you
+//   then invoke protoc with the parameter --NAME_out=OUT_DIR (again, replace
+//   "NAME" with your plugin's name), protoc will invoke your plugin to generate
+//   the output, which will be placed in OUT_DIR.
+// * Place the plugin binary anywhere, with any name, and pass the --plugin
+//   parameter to protoc to direct it to your plugin like so:
+//     protoc --plugin=protoc-gen-NAME=path/to/mybinary --NAME_out=OUT_DIR
+//   On Windows, make sure to include the .exe suffix:
+//     protoc --plugin=protoc-gen-NAME=path/to/mybinary.exe --NAME_out=OUT_DIR
+
+#ifndef GOOGLE_PROTOBUF_COMPILER_PLUGIN_H__
+#define GOOGLE_PROTOBUF_COMPILER_PLUGIN_H__
+
+#include <string>
+
+#include <google/protobuf/port_def.inc>
+
+namespace google {
+namespace protobuf {
+namespace compiler {
+
+class CodeGenerator;  // code_generator.h
+class CodeGeneratorRequest;
+class CodeGeneratorResponse;
+
+// Implements main() for a protoc plugin exposing the given code generator.
+PROTOC_EXPORT int PluginMain(int argc, char* argv[],
+                             const CodeGenerator* generator);
+
+// Generates code using the given code generator. Returns true if the code
+// generation is successful. If the code generation fails, error_msg may be
+// populated to describe the failure cause.
+bool GenerateCode(const CodeGeneratorRequest& request,
+                  const CodeGenerator& generator,
+                  CodeGeneratorResponse* response, std::string* error_msg);
+
+}  // namespace compiler
+}  // namespace protobuf
+}  // namespace google
+
+#include <google/protobuf/port_undef.inc>
+
+#endif  // GOOGLE_PROTOBUF_COMPILER_PLUGIN_H__