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// This source code is released into the public domain.
export module nihil.config:option;
import nihil.std;
import nihil.error;
import nihil.ucl;
namespace nihil::config {
// Base class for options; this is what config_store interacts with.
//
// Base classes should override the four protected functions:
//
// get_string()
// set_string()
// get_ucl()
// set_ucl()
//
// Overriding any other members is not permitted.
export struct option
{
virtual ~option();
// Short name of this option.
[[nodiscard]] auto name(this option const &) noexcept
-> std::string_view;
// Human-readable description of this option.
[[nodiscard]] auto description(this option const &) noexcept
-> std::string_view;
// If true, this option is set to its default value.
[[nodiscard]] auto is_default(this option const &) noexcept
-> bool;
/*
* Get or set this option as a string. The specific conversion
* method depends on the derived option type.
*/
[[nodiscard]] auto string(this option const &) -> std::string;
[[nodiscard]] auto string(this option &, std::string_view value)
-> std::expected<void, error>;
/*
* Return this object as a UCL object. This is used when writing the
* configuration file.
*/
[[nodiscard]] auto ucl(this option const &)
-> std::expected<ucl::object, error>;
/*
* Set this object from a UCL object. This is used when reading the
* configuration file.
*/
[[nodiscard]] auto ucl(this option &, ucl::object const &)
-> std::expected<void, error>;
// Not copyable or movable.
option(option const &) = delete;
auto operator=(option const &) -> option& = delete;
option(option &&) = delete;
auto operator=(option &&) -> option& = delete;
protected:
option(std::string_view name, std::string_view description);
auto is_default(this option &, bool) -> void;
/*
* Get or set this option as a string.
*/
[[nodiscard]] virtual auto get_string() const
-> std::string = 0;
[[nodiscard]] virtual auto set_string(std::string_view)
-> std::expected<void, error> = 0;
/*
* Get or set this option as a UCL object.
*/
[[nodiscard]] virtual auto get_ucl() const
-> std::expected<ucl::object, error> = 0;
[[nodiscard]] virtual auto set_ucl(ucl::object const &)
-> std::expected<void, error> = 0;
private:
std::string m_name;
std::string m_description;
bool m_is_default = true;
};
/*
* Make options printable. This is mostly useful for testing.
*/
export auto operator<<(std::ostream &strm, option const &opt) -> std::ostream &;
} // namespace nihil
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