yaml.hpp

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// Copyright (c) 2023 Petter Nilsson. MIT License. https://github.com/pettni/ezconfig
 
#pragma once
 
#include <yaml-cpp/yaml.h>
 
#include "factory.hpp"
#include "yaml_fwd.hpp"
 
#define EZ_YAML_DEFINE(Base)                                                 \
  EZ_FACTORY_DEFINE(Base, const YAML::Node &);                               \
  template std::unique_ptr<Base> ezconfig::yaml::Create(const YAML::Node &); \
  template struct YAML::convert<std::shared_ptr<Base>>;                      \
  template struct YAML::convert<std::unique_ptr<Base>>
 
#define EZ_YAML_REGISTER(Base, tag, Derived, ...) \
  EZ_STATIC_INVOKE(&ezconfig::yaml::Add<Base, Derived __VA_OPT__(, ) __VA_ARGS__>, tag)
 
namespace ezconfig::yaml {
 
// clang-format off
template<typename T>
concept YamlParseable = requires(const YAML::Node & y) {
  {y.as<T>()} -> std::convertible_to<T>;
};
// clang-format on
 
template<typename Base, typename Derived, typename Intermediate = Derived>
  requires(
    std::is_base_of_v<Base, Derived> && YamlParseable<Intermediate>
    && std::is_constructible_v<Derived, Intermediate &&>)
void Add(const std::string & tag)
{
  if (tag.size() < 2 || tag[0] != '!') { throw std::logic_error("yaml tag must start with !"); }
  auto creator = [](const YAML::Node & y) { return std::make_unique<Derived>(y.as<Intermediate>()); };
  EZ_FACTORY_INSTANCE(Base, const YAML::Node &).add(tag, std::move(creator));
}
 
template<typename Base>
std::unique_ptr<Base> Create(const YAML::Node & y)
{
  return EZ_FACTORY_INSTANCE(Base, const YAML::Node &).create(y.Tag(), y);
}
 
}  // namespace ezconfig::yaml
 
template<ezconfig::yaml::Constructible Base>
bool YAML::convert<std::shared_ptr<Base>>::decode(const YAML::Node & y, std::shared_ptr<Base> & ptr)
{
  ptr = ::ezconfig::yaml::Create<Base>(y);
  return true;
}
 
template<ezconfig::yaml::Constructible Base>
bool YAML::convert<std::unique_ptr<Base>>::decode(const YAML::Node & y, std::unique_ptr<Base> & ptr)
{
  ptr = ::ezconfig::yaml::Create<Base>(y);
  return true;
}