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#ifndef GI_EXPECTED_HPP
#define GI_EXPECTED_HPP
#if __has_include("nonstd/expected.hpp")
#include "nonstd/expected.hpp"
#else
#include <expected>
#endif
#include "base.hpp"
#include "exception.hpp"
namespace gi
{
// alias so we might route to a std type some day ...
template<typename T, typename E>
#ifdef expected_lite_VERSION
using expected = nonstd::expected<T, E>;
#else
using expected = std::expected<T, E>;
#endif
// standardize on glib error
template<typename T>
using result = expected<T, repository::GLib::Error>;
namespace detail
{
#ifdef expected_lite_VERSION
inline nonstd::unexpected_type<repository::GLib::Error>
make_unexpected(GError *error)
{
assert(error);
return nonstd::make_unexpected(repository::GLib::Error(error));
}
inline nonstd::unexpected_type<repository::GLib::Error>
make_unexpected(repository::GLib::Error error)
{
assert(error);
return nonstd::make_unexpected(std::move(error));
}
#else
inline std::unexpected<repository::GLib::Error>
make_unexpected(GError *error)
{
assert(error);
return std::unexpected<repository::GLib::Error>(error);
}
#endif
} // namespace detail
// no forwarding reference; T must be non-reference type
template<typename T>
result<T>
make_result(T t, GError *error)
{
if (error)
return detail::make_unexpected(error);
return t;
}
// rough helpers to unwrap result/expected
// unwrap by move
template<typename T>
T
expect(gi::result<T> &&t)
{
if (!t)
detail::try_throw(std::move(t.error()));
return std::move(*t);
}
namespace detail
{
template<typename T>
void test_result(const gi::result<T> &);
template<typename T>
int test_result(const T &);
template<typename T>
using is_result = std::is_same<void,
decltype(test_result(std::forward<T>(std::declval<T>())))>;
} // namespace detail
// should only be used for a non-result
// (e.g. avoid l-value result ending up here)
template<typename T, typename Enable = typename std::enable_if<
!detail::is_result<T>::value>::type>
T
expect(T &&t)
{
return std::forward<T>(t);
}
template<typename T>
struct rv
{
#if GI_DL && GI_EXPECTED
using type = gi::result<T>;
#else
using type = T;
#endif
};
} // namespace gi
#endif // GI_EXPECTED_HPP
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