cxx_dto_generator.cpp

#include <google/protobuf/compiler/code_generator.h>
#include <google/protobuf/compiler/command_line_interface.h>
#include <google/protobuf/compiler/plugin.h>
#include <google/protobuf/compiler/cpp/cpp_helpers.h>
#include <google/protobuf/io/printer.h>
#include <google/protobuf/io/zero_copy_stream.h>

#include <map>
#include <memory>
#include <string>

namespace {

void GenerateHeader(auto *printer, auto const &args) {
    printer->Print(args,
            "#ifndef C_DTO_$filename_identifier$_H_\n"
            "#define C_DTO_$filename_identifier$_H_\n"
            "#endif\n");
}

void GenerateSource(auto *printer, auto const &args) {
    printer->Print(args,
            "#include \"$filename$.h\"\n");
}

class DtoGenerator : public google::protobuf::compiler::CodeGenerator {
public:
    bool Generate(google::protobuf::FileDescriptor const *file,
            std::string const &parameter,
            google::protobuf::compiler::OutputDirectory *out_dir,
            std::string *err) const {
        using namespace google::protobuf;

        std::string basename = compiler::cpp::StripProto(file->name());
        basename.append(".c_dto");

        std::map<std::string, std::string> args{
            {"filename", basename},
            {"filename_identifier", compiler::cpp::FilenameIdentifier(file->name())},
        };

        // Generate header.
        std::unique_ptr<io::ZeroCopyOutputStream> h_out{out_dir->Open(basename + ".h")};
        io::Printer h_printer(h_out.get(), '$');
        GenerateHeader(&h_printer, args);

        // Generate source.
        std::unique_ptr<io::ZeroCopyOutputStream> c_out{out_dir->Open(basename + ".c")};
        io::Printer c_printer(c_out.get(), '$');
        GenerateSource(&c_printer, args);

        return true;
    }
};

} // namespace

int main(int argc, char **argv) {
    DtoGenerator generator{};

    if (true) {
        google::protobuf::compiler::CommandLineInterface cli;
        cli.RegisterGenerator("--cxx_dto_out", &generator, "Generate C++ dtos.");
        cli.SetVersionInfo("0.0.1");
        return cli.Run(argc, argv);
    }

    return google::protobuf::compiler::PluginMain(argc, argv, &generator);
}