protobuf/upb_generator/plugin.h

// Protocol Buffers - Google's data interchange format
// Copyright 2023 Google LLC.  All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

#ifndef UPB_UPB_GENERATOR_PLUGIN_H_
#define UPB_UPB_GENERATOR_PLUGIN_H_

#include <stdio.h>

#include <cstring>
#include <string>
#include <utility>
#include <vector>

#ifdef _WIN32
#include <fcntl.h>
#include <io.h>
#endif

#include "absl/container/flat_hash_set.h"
#include "absl/log/absl_log.h"
#include "absl/strings/string_view.h"
#include "google/protobuf/compiler/code_generator_lite.h"
#include "upb/base/status.hpp"
#include "upb/base/string_view.h"
#include "upb/mem/arena.h"
#include "upb/mem/arena.hpp"
#include "upb/reflection/def.hpp"
#include "upb/reflection/descriptor_bootstrap.h"
#include "upb_generator/plugin_bootstrap.h"

// Must be last.
#include "upb/port/def.inc"

namespace upb {
namespace generator {

inline std::vector<std::pair<std::string, std::string>> ParseGeneratorParameter(
    const absl::string_view text) {
  std::vector<std::pair<std::string, std::string>> ret;
  google::protobuf::compiler::ParseGeneratorParameter(text, &ret);
  return ret;
}

class Plugin {
 public:
  Plugin() { ReadRequest(); }
  ~Plugin() { WriteResponse(); }

  absl::string_view parameter() const {
    return ToStringView(
        UPB_DESC(compiler_CodeGeneratorRequest_parameter)(request_));
  }

  template <class T>
  void GenerateFilesRaw(T&& func) {
    absl::flat_hash_set<absl::string_view> files_to_generate;
    size_t size;
    const upb_StringView* file_to_generate = UPB_DESC(
        compiler_CodeGeneratorRequest_file_to_generate)(request_, &size);
    for (size_t i = 0; i < size; i++) {
      files_to_generate.insert(
          {file_to_generate[i].data, file_to_generate[i].size});
    }

    const UPB_DESC(FileDescriptorProto)* const* files =
        UPB_DESC(compiler_CodeGeneratorRequest_proto_file)(request_, &size);
    for (size_t i = 0; i < size; i++) {
      upb::Status status;
      absl::string_view name =
          ToStringView(UPB_DESC(FileDescriptorProto_name)(files[i]));
      func(files[i], files_to_generate.contains(name));
    }
  }

  template <class T>
  void GenerateFiles(T&& func) {
    GenerateFilesRaw(
        [this, &func](const UPB_DESC(FileDescriptorProto) * file_proto,
                      bool generate) {
          upb::Status status;
          upb::FileDefPtr file = pool_.AddFile(file_proto, &status);
          if (!file) {
            absl::string_view name =
                ToStringView(UPB_DESC(FileDescriptorProto_name)(file_proto));
            ABSL_LOG(FATAL) << "Couldn't add file " << name
                            << " to DefPool: " << status.error_message();
          }
          if (generate) func(file);
        });
  }

  void SetError(absl::string_view error) {
    char* data =
        static_cast<char*>(upb_Arena_Malloc(arena_.ptr(), error.size()));
    memcpy(data, error.data(), error.size());
    UPB_DESC(compiler_CodeGeneratorResponse_set_error)
    (response_, upb_StringView_FromDataAndSize(data, error.size()));
  }

  void AddOutputFile(absl::string_view filename, absl::string_view content) {
    UPB_DESC(compiler_CodeGeneratorResponse_File)* file = UPB_DESC(
        compiler_CodeGeneratorResponse_add_file)(response_, arena_.ptr());
    UPB_DESC(compiler_CodeGeneratorResponse_File_set_name)
    (file, StringDup(filename));
    UPB_DESC(compiler_CodeGeneratorResponse_File_set_content)
    (file, StringDup(content));
  }

 private:
  upb::Arena arena_;
  upb::DefPool pool_;
  UPB_DESC(compiler_CodeGeneratorRequest) * request_;
  UPB_DESC(compiler_CodeGeneratorResponse) * response_;

  static absl::string_view ToStringView(upb_StringView sv) {
    return absl::string_view(sv.data, sv.size);
  }

  upb_StringView StringDup(absl::string_view s) {
    char* data =
        reinterpret_cast<char*>(upb_Arena_Malloc(arena_.ptr(), s.size()));
    memcpy(data, s.data(), s.size());
    return upb_StringView_FromDataAndSize(data, s.size());
  }

  std::string ReadAllStdinBinary() {
    std::string data;
#ifdef _WIN32
    _setmode(_fileno(stdin), _O_BINARY);
    _setmode(_fileno(stdout), _O_BINARY);
#endif
    char buf[4096];
    while (size_t len = fread(buf, 1, sizeof(buf), stdin)) {
      data.append(buf, len);
    }
    return data;
  }

  void ReadRequest() {
    std::string data = ReadAllStdinBinary();
    request_ = UPB_DESC(compiler_CodeGeneratorRequest_parse)(
        data.data(), data.size(), arena_.ptr());
    if (!request_) {
      ABSL_LOG(FATAL) << "Failed to parse CodeGeneratorRequest";
    }
    response_ = UPB_DESC(compiler_CodeGeneratorResponse_new)(arena_.ptr());

    int features =
        UPB_DESC(compiler_CodeGeneratorResponse_FEATURE_PROTO3_OPTIONAL) |
        UPB_DESC(compiler_CodeGeneratorResponse_FEATURE_SUPPORTS_EDITIONS);
    UPB_DESC(compiler_CodeGeneratorResponse_set_supported_features)
    (response_, features);
    UPB_DESC(compiler_CodeGeneratorResponse_set_minimum_edition)
    (response_, UPB_DESC(EDITION_PROTO2));
    UPB_DESC(compiler_CodeGeneratorResponse_set_maximum_edition)
    (response_, UPB_DESC(EDITION_2023));
  }

  void WriteResponse() {
    size_t size;
    char* serialized = UPB_DESC(compiler_CodeGeneratorResponse_serialize)(
        response_, arena_.ptr(), &size);
    if (!serialized) {
      ABSL_LOG(FATAL) << "Failed to serialize CodeGeneratorResponse";
    }

    if (fwrite(serialized, 1, size, stdout) != size) {
      ABSL_LOG(FATAL) << "Failed to write response to stdout";
    }
  }
};

}  // namespace generator
}  // namespace upb

#include "upb/port/undef.inc"

#endif  // UPB_UPB_GENERATOR_PLUGIN_H_