input.hpp

#pragma once
 
#include <cassert>
#include <optional>
#include <stdexcept>
#include <vector>
 
#include "vipra/concepts/string_view.hpp"
 
#include "vipra/modules/module.hpp"
 
#include "vipra/util/crtp.hpp"
 
// TODO(rolland): remember to add in documentation that inputs should hold off on loading until their load() method is called
 
namespace VIPRA::Modules {
 
template <typename module_t>
class Input : public Util::CRTP<Input<module_t>> {
  using Util::CRTP<Input<module_t>>::self;
 
 public:
  void load()
  {
    // TODO(rolland) maybe have load_impl return a bool and handle if it failed?
    if ( _loaded ) return;
    _loaded = true;
    self().load_impl();
  }

  template <typename data_t, Concepts::StringView... keys_t>
  auto get(keys_t&&... keys) const -> std::optional<data_t>
  {
    assert(_loaded);
 
    try {
      return self().template get_impl<data_t>(
          std::string_view(std::forward<keys_t>(keys))...);
    }
    catch ( std::exception& ex ) {
      // TODO(rolland): if the input module has an issue should we just let it throw or just return nullopt like this?
      // If the module has an issue getting the value return nullopt
      return std::nullopt;
    }
  }
 
  void set_loaded(bool loaded) { _loaded = loaded; }
 
 private:
  bool _loaded = false;
};
 
}  // namespace VIPRA::Modules