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Support mapping no-arg functions for void expecteds

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This commit is contained in:
Simon Brand
2018-08-24 10:08:20 +01:00
parent d7cf0688f1
commit 4aa086e242
2 changed files with 36 additions and 0 deletions
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10
tests/extensions.cpp
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@@ -572,3 +572,13 @@ TEST_CASE("14", "[issue.14]") {
});
}
TEST_CASE("32", "[issue.32]") {
int i = 0;
tl::expected<void, int> a;
a.map([&i]{i = 42;});
REQUIRE(i == 42);
auto x = a.map([]{return 42;});
REQUIRE(*x == 42);
}

26
tl/expected.hpp
View File

@@ -1934,6 +1934,7 @@ constexpr auto and_then_impl(Exp &&exp, F &&f) -> Ret {
#ifdef TL_EXPECTED_CXX14
template <class Exp, class F,
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
@@ -1945,6 +1946,7 @@ constexpr auto expected_map_impl(Exp &&exp, F &&f) {
}
template <class Exp, class F,
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
@@ -1957,6 +1959,30 @@ auto expected_map_impl(Exp &&exp, F &&f) {
return result(unexpect, std::forward<Exp>(exp).error());
}
template <class Exp, class F,
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto expected_map_impl(Exp &&exp, F &&f) {
using result = ret_t<Exp, detail::decay_t<Ret>>;
return exp.has_value() ? result(detail::invoke(std::forward<F>(f)))
: result(unexpect, std::forward<Exp>(exp).error());
}
template <class Exp, class F,
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
auto expected_map_impl(Exp &&exp, F &&f) {
using result = expected<void, err_t<Exp>>;
if (exp.has_value()) {
detail::invoke(std::forward<F>(f));
return result();
}
return result(unexpect, std::forward<Exp>(exp).error());
}
#else
template <class Exp, class F,
class Ret = decltype(detail::invoke(std::declval<F>(),