coffee/continuable
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This commit is contained in:
Denis Blank 2017-11-22 02:11:27 +01:00
parent 91b75953a6
commit 0f5dd265fd
1 changed files with 56 additions and 15 deletions
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69
include/continuable/detail/expected.hpp
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@ -42,22 +42,66 @@ namespace cti {
namespace detail { namespace detail {
namespace expected { namespace expected {
namespace detail { namespace detail {
template <bool IsCopyable, typename Base> enum class slot_t { empty, value, error };
struct expected_base {
explicit expected_base(expected_base const& right) { template <typename Base>
static_cast<Base const*>(&right)->visit([&](auto&& value) { struct expected_base_util {
slot_t slot_;
protected:
template <typename T>
void init(T&& value, slot_t slot) {
set(slot);
using type = std::decay_t<decltype(value)>; using type = std::decay_t<decltype(value)>;
auto storage = &static_cast<Base*>(this)->storage_; auto storage = &base()->storage_;
new (storage) type(std::forward<decltype(value)>(value)); new (storage) type(std::forward<decltype(value)>(value));
}
void destroy() {
weak_destroy();
set(slot_t::empty);
}
void weak_destroy() {
base()->visit([&](auto&& value) {
using type = std::decay_t<decltype(value)>;
value.~type();
}); });
} }
expected_base& operator=(expected_base const& right) { slot_t get() const noexcept {
static_cast<Base const*>(&right)->visit([&](auto&& value) { return slot_;
using type = std::decay_t<decltype(value)>; }
auto storage = &static_cast<Base*>(this)->storage_; bool is(slot_t slot) const noexcept {
new (storage) type(std::forward<decltype(value)>(value)); return get() == slot;
}
void set(slot_t slot) {
slot_ = slot;
}
slot_t consume(slot_t slot) {
auto current = get();
destroy();
return current;
}
Base* base() noexcept {
return static_cast<Base*>(this);
}
Base const* base() const noexcept {
return static_cast<Base*>(this);
}
};
template <bool IsCopyable, typename Base>
struct expected_base : expected_base_util<Base> {
explicit expected_base(expected_base const& right) {
right.visit([&](auto&& value) {
this->init(std::forward<decltype(value)>(value));
}); });
return *this; set(right.consume());
}
expected_base& operator=(expected_base const& right) {
this->weak_destroy();
right.visit([&](auto&& value) {
this->init(std::forward<decltype(value)>(value));
});
set(right.consume());
} }
}; };
} // namespace detail } // namespace detail
@ -70,10 +114,7 @@ template <typename T, typename Storage = std::aligned_storage_t<std::max(
class expected { class expected {
friend class expected_base; friend class expected_base;
enum class slot_t { empty, value, error };
Storage storage_; Storage storage_;
slot_t slot_;
public: public:
explicit expected() : slot_(slot_t::empty) { explicit expected() : slot_(slot_t::empty) {