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Support void for map_error

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Simon Brand
2017-12-03 08:25:19 +00:00
parent e081092fb1
commit 9423013aca
2 changed files with 97 additions and 14 deletions
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63
expected.hpp
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@@ -921,9 +921,9 @@ public:
/// \group and_then
/// Carries out some operation which returns an expected on the stored object
/// if there is one. \requires `std::invoke(std::forward<F>(f), value())`
/// returns a `std::expected<U>` for some `U`. \returns Let `U` be the result
/// of `std::invoke(std::forward<F>(f), value())`. Returns a
/// `std::expected<U>`. The return value is empty if `*this` is empty,
/// returns an `expected<U>` for some `U`. \returns Let `U` be the result
/// of `std::invoke(std::forward<F>(f), value())`. Returns an
/// `expected<U>`. The return value is empty if `*this` is empty,
/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
/// is returned.
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
@@ -975,9 +975,9 @@ public:
/// \group and_then
/// Carries out some operation which returns an expected on the stored object
/// if there is one. \requires `std::invoke(std::forward<F>(f), value())`
/// returns a `std::expected<U>` for some `U`. \returns Let `U` be the result
/// of `std::invoke(std::forward<F>(f), value())`. Returns a
/// `std::expected<U>`. The return value is empty if `*this` is empty,
/// returns an `expected<U>` for some `U`. \returns Let `U` be the result
/// of `std::invoke(std::forward<F>(f), value())`. Returns an
/// `expected<U>`. The return value is empty if `*this` is empty,
/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
/// is returned.
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
@@ -1034,7 +1034,8 @@ public:
!defined(TL_EXPECTED_GCC54)
/// \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),
/// value())`. Returns a `std::expected<U,E>`. If `*this` is unexpected, the
/// value())`. If `U` is `void`, returns an `expected<monostate,E>, otherwise
// returns an `expected<U,E>`. If `*this` is unexpected, the
/// result is `*this`, otherwise an `expected<U,E>` is constructed from the
/// return value of `std::invoke(std::forward<F>(f), value())` and is
/// returned.
@@ -1065,7 +1066,8 @@ public:
#else
/// \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),
/// value())`. Returns a `std::expected<U,E>`. If `*this` is unexpected, the
/// value())`. If `U` is `void`, returns an `expected<monostate,E>, otherwise
// returns an `expected<U,E>`. If `*this` is unexpected, the
/// result is `*this`, otherwise an `expected<U,E>` is constructed from the
/// return value of `std::invoke(std::forward<F>(f), value())` and is
/// returned.
@@ -1114,7 +1116,8 @@ public:
/// \brief Carries out some operation on the stored unexpected object if there
/// is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. Returns a `std::expected<T,U>`. If `*this` has an expected
/// value())`. If `U` is `void`, returns an `expected<T,monostate>`, otherwise
/// returns an `expected<T,U>`. If `*this` has an expected
/// value, the result is `*this`, otherwise an `expected<T,U>` is constructed
/// from `make_unexpected(std::invoke(std::forward<F>(f), value()))` and is
/// returned.
@@ -1146,7 +1149,7 @@ public:
/// \brief Carries out some operation on the stored unexpected object if there
/// is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. Returns a `std::expected<T,U>`. If `*this` has an expected
/// value())`. Returns an `expected<T,U>`. If `*this` has an expected
/// value, the result is `*this`, otherwise an `expected<T,U>` is constructed
/// from `make_unexpected(std::invoke(std::forward<F>(f), value()))` and is
/// returned.
@@ -1622,6 +1625,7 @@ public:
/// \exclude
namespace detail {
template <class Exp> using exp_t = typename detail::decay_t<Exp>::error_type;
template <class Exp> using err_t = typename detail::decay_t<Exp>::error_type;
template <class Exp, class Ret> using ret_t = expected<Ret, err_t<Exp>>;
@@ -1683,19 +1687,35 @@ auto map_impl(Exp &&exp, F &&f) -> expected<monostate, err_t<Exp>> {
!defined(TL_EXPECTED_GCC54)
template <class Exp, class F,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>()))>
*std::declval<Exp>())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto map_error_impl(Exp &&exp, F &&f) {
using result = ret_t<Exp, Ret>;
using result = expected<exp_t<Exp>, Ret>;
return exp.has_value()
? result(*std::forward<Exp>(exp))
: result(unexpect, detail::invoke(std::forward<F>(f),
std::forward<Exp>(exp).error()));
}
template <class Exp, class F,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
constexpr auto map_error_impl(Exp &&exp, F &&f) {
using result = expected<exp_t<Exp>, monostate>;
if (exp.has_value()) {
return result(*std::forward<Exp>(exp));
}
detail::invoke(std::forward<F>(f),
std::forward<Exp>(exp).error());
return result(unexpect, monostate{});
}
#else
template <class Exp, class F,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>()))>
constexpr auto map_error_impl(Exp &&exp, F &&f) -> ret_t<Exp, Ret> {
*std::declval<Exp>())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto map_error_impl(Exp &&exp, F &&f) -> expected<exp_t<Exp>, Ret> {
using result = ret_t<Exp, Ret>;
return exp.has_value()
@@ -1703,6 +1723,21 @@ constexpr auto map_error_impl(Exp &&exp, F &&f) -> ret_t<Exp, Ret> {
: result(unexpect, detail::invoke(std::forward<F>(f),
std::forward<Exp>(exp).error()));
}
template <class Exp, class F,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
constexpr auto map_error_impl(Exp &&exp, F &&f) -> expected<exp_t<Exp>, monostate> {
using result = expected<exp_t<Exp>, monostate>;
if (exp.has_value()) {
return result(*std::forward<Exp>(exp));
}
detail::invoke(std::forward<F>(f),
std::forward<Exp>(exp).error());
return result(unexpect, monostate{});
}
#endif
template <class Exp, class F,

48
tests/extensions.cpp
View File

@@ -191,6 +191,54 @@ TEST_CASE("Map error extensions", "[extensions.map_error]") {
REQUIRE(!ret);
REQUIRE(ret.error() == 42);
}
{
tl::expected<int, int> e = 21;
auto ret = e.map_error(ret_void);
REQUIRE(ret);
}
{
const tl::expected<int, int> e = 21;
auto ret = e.map_error(ret_void);
REQUIRE(ret);
}
{
tl::expected<int, int> e = 21;
auto ret = std::move(e).map_error(ret_void);
REQUIRE(ret);
}
{
const tl::expected<int, int> e = 21;
auto ret = std::move(e).map_error(ret_void);
REQUIRE(ret);
}
{
tl::expected<int, int> e(tl::unexpect, 21);
auto ret = e.map_error(ret_void);
REQUIRE(!ret);
}
{
const tl::expected<int, int> e(tl::unexpect, 21);
auto ret = e.map_error(ret_void);
REQUIRE(!ret);
}
{
tl::expected<int, int> e(tl::unexpect, 21);
auto ret = std::move(e).map_error(ret_void);
REQUIRE(!ret);
}
{
const tl::expected<int, int> e(tl::unexpect, 21);
auto ret = std::move(e).map_error(ret_void);
REQUIRE(!ret);
}
}
TEST_CASE("And then extensions", "[extensions.and_then]") {