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C++11 and_then

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Simon Brand
2017-10-27 12:11:49 +01:00
parent ea4ff00802
commit 4cf83fcbd6
1 changed files with 59 additions and 0 deletions
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59
expected.hpp
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@@ -432,6 +432,7 @@ public:
typedef E error_type;
typedef unexpected<E> unexpected_type;
#ifdef TL_EXPECTED_CXX14
/// \group and_then
/// Carries out some operation which returns an optional on the stored object
/// if there is one. \requires `std::invoke(std::forward<F>(f), value())`
@@ -486,6 +487,64 @@ public:
}
#endif
#else
/// \group and_then
/// Carries out some operation which returns an optional on the stored object
/// if there is one. \requires `std::invoke(std::forward<F>(f), value())`
/// returns a `std::optional<U>` for some `U`. \returns Let `U` be the result
/// of `std::invoke(std::forward<F>(f), value())`. Returns a
/// `std::optional<U>`. The return value is empty if `*this` is empty,
/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
/// is returned. \group and_then \synopsis template <class F>\nconstexpr auto
/// and_then(F &&f) &;
template <class F>
TL_EXPECTED_11_CONSTEXPR detail::invoke_result_t<F, T &> and_then(F &&f) & {
using result = detail::invoke_result_t<F, T &>;
static_assert(detail::is_expected<result>::value,
"F must return an expected");
return has_value() ? detail::invoke(std::forward<F>(f), **this)
: result(unexpect, this->error());
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
template <class F>
TL_EXPECTED_11_CONSTEXPR detail::invoke_result_t<F, T &&> and_then(F &&f) && {
using result = detail::invoke_result_t<F, T &&>;
static_assert(detail::is_expected<result>::value,
"F must return an expected");
return has_value() ? detail::invoke(std::forward<F>(f), **this)
: result(unexpect, std::move(this->error()));
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &;
template <class F>
constexpr detail::invoke_result_t<F, const T &> and_then(F &&f) const & {
using result = detail::invoke_result_t<F, const T &>;
static_assert(detail::is_expected<result>::value,
"F must return an expected");
return has_value() ? detail::invoke(std::forward<F>(f), **this)
: result(unexpect, this->error());
}
#ifndef TL_EXPECTED_NO_CONSTRR
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
template <class F>
constexpr detail::invoke_result_t<F, const T &&> and_then(F &&f) const && {
using result = detail::invoke_result_t<F, const T &&>;
static_assert(detail::is_expected<result>::value,
"F must return an expected");
return has_value() ? detail::invoke(std::forward<F>(f), **this)
: result(unexpect, std::move(this->error()));
}
#endif
#ifdef TL_EXPECTED_CXX14
/// \brief Carries out some operation on the stored object if there is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),