flat_translator.cpp

/*
 * Copyright 2016 Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <thrift/lib/cpp2/fatal/container_traits.h>
#include <thrift/lib/cpp2/fatal/reflection.h>

#include <thrift/lib/cpp2/fatal/demo/json_print.h>

#include <thrift/lib/cpp2/fatal/demo/gen-cpp2/flat_config_constants.h>
#include <thrift/lib/cpp2/fatal/demo/gen-cpp2/flat_config_fatal_types.h>
#include <thrift/lib/cpp2/fatal/demo/gen-cpp2/legacy_config_constants.h>

#include <folly/Conv.h>
#include <folly/init/Init.h>


#include <iostream>
#include <string>

using namespace apache::thrift;
using namespace static_reflection::demo;

struct get_property {
  template <typename Member>
  using apply = typename Member::annotations::values::property;
};

struct legacy_to_flat_translator {
  template <typename Member>
  void operator ()(
    fatal::tag<Member>,
    std::string const &from,
    flat_config &to
  ) const {
    auto &value = Member::getter::ref(to);
    value = folly::to<typename Member::type>(from);
  }
};

void translate(legacy_config const &from, flat_config &to) {
  for (auto const &i: from) {
    fatal::trie_find<reflect_struct<flat_config>::members, get_property>(
      i.first.begin(),
      i.first.end(),
      legacy_to_flat_translator(),
      i.second,
      to
    );
  }
}

struct flat_to_legacy_translator {
  template <typename Member, std::size_t Index>
  void operator ()(
    fatal::indexed<Member, Index>,
    flat_config const &from,
    legacy_config &to
  ) {
    using property = typename Member::annotations::values::property;
    auto const key = fatal::z_data<property>();
    auto const &value = Member::getter::ref(from);
    to[key] = folly::to<std::string>(value);
  }
};

void translate(flat_config const &from, legacy_config &to) {
  using members = reflect_struct<flat_config>::members;

  fatal::foreach<members>(
    flat_to_legacy_translator(),
    from,
    to
  );
}

template <typename To, typename From>
void test(From const &from) {
  To to;
  translate(from, to);
  print(from);
  print(to);
}

int main(int argc, char **argv) {
  folly::init(&argc, &argv);

  std::cerr << "legacy -> flat: ";
  test<static_reflection::demo::flat_config>(
    static_reflection::demo::legacy_config_constants::example()
  );

  std::cerr << "flat -> legacy: ";
  test<static_reflection::demo::legacy_config>(
    static_reflection::demo::flat_config_constants::example()
  );

  return 0;
}