mirror of https://github.com/bsnes-emu/bsnes.git
92 lines
3.4 KiB
C++
92 lines
3.4 KiB
C++
#pragma once
|
|
|
|
namespace nall {
|
|
|
|
struct nothing_t {};
|
|
static nothing_t nothing;
|
|
|
|
template<typename T>
|
|
struct maybe {
|
|
inline maybe() {}
|
|
inline maybe(nothing_t) {}
|
|
inline maybe(const T& source) { operator=(source); }
|
|
inline maybe(T&& source) { operator=(move(source)); }
|
|
inline maybe(const maybe& source) { operator=(source); }
|
|
inline maybe(maybe&& source) { operator=(move(source)); }
|
|
inline ~maybe() { reset(); }
|
|
|
|
inline auto operator=(nothing_t) -> maybe& { reset(); return *this; }
|
|
inline auto operator=(const T& source) -> maybe& { reset(); _valid = true; new(&_value.t) T(source); return *this; }
|
|
inline auto operator=(T&& source) -> maybe& { reset(); _valid = true; new(&_value.t) T(move(source)); return *this; }
|
|
|
|
inline auto operator=(const maybe& source) -> maybe& {
|
|
if(this == &source) return *this;
|
|
reset();
|
|
if(_valid = source._valid) new(&_value.t) T(source.get());
|
|
return *this;
|
|
}
|
|
|
|
inline auto operator=(maybe&& source) -> maybe& {
|
|
if(this == &source) return *this;
|
|
reset();
|
|
if(_valid = source._valid) new(&_value.t) T(move(source.get()));
|
|
source._valid = false;
|
|
return *this;
|
|
}
|
|
|
|
inline explicit operator bool() const { return _valid; }
|
|
inline auto reset() -> void { if(_valid) { _value.t.~T(); _valid = false; } }
|
|
inline auto data() -> T* { return _valid ? &_value.t : nullptr; }
|
|
inline auto get() -> T& { assert(_valid); return _value.t; }
|
|
|
|
inline auto data() const -> const T* { return ((maybe*)this)->data(); }
|
|
inline auto get() const -> const T& { return ((maybe*)this)->get(); }
|
|
inline auto operator->() -> T* { return data(); }
|
|
inline auto operator->() const -> const T* { return data(); }
|
|
inline auto operator*() -> T& { return get(); }
|
|
inline auto operator*() const -> const T& { return get(); }
|
|
inline auto operator()() -> T& { return get(); }
|
|
inline auto operator()() const -> const T& { return get(); }
|
|
inline auto operator()(const T& invalid) const -> const T& { return _valid ? get() : invalid; }
|
|
|
|
private:
|
|
union U {
|
|
T t;
|
|
U() {}
|
|
~U() {}
|
|
} _value;
|
|
bool _valid = false;
|
|
};
|
|
|
|
template<typename T>
|
|
struct maybe<T&> {
|
|
inline maybe() : _value(nullptr) {}
|
|
inline maybe(nothing_t) : _value(nullptr) {}
|
|
inline maybe(const T& source) : _value((T*)&source) {}
|
|
inline maybe(const maybe& source) : _value(source._value) {}
|
|
|
|
inline auto operator=(nothing_t) -> maybe& { _value = nullptr; return *this; }
|
|
inline auto operator=(const T& source) -> maybe& { _value = (T*)&source; return *this; }
|
|
inline auto operator=(const maybe& source) -> maybe& { _value = source._value; return *this; }
|
|
|
|
inline explicit operator bool() const { return _value; }
|
|
inline auto reset() -> void { _value = nullptr; }
|
|
inline auto data() -> T* { return _value; }
|
|
inline auto get() -> T& { assert(_value); return *_value; }
|
|
|
|
inline auto data() const -> const T* { return ((maybe*)this)->data(); }
|
|
inline auto get() const -> const T& { return ((maybe*)this)->get(); }
|
|
inline auto operator->() -> T* { return data(); }
|
|
inline auto operator->() const -> const T* { return data(); }
|
|
inline auto operator*() -> T& { return get(); }
|
|
inline auto operator*() const -> const T& { return get(); }
|
|
inline auto operator()() -> T& { return get(); }
|
|
inline auto operator()() const -> const T& { return get(); }
|
|
inline auto operator()(const T& invalid) const -> const T& { return _value ? get() : invalid; }
|
|
|
|
private:
|
|
T* _value;
|
|
};
|
|
|
|
}
|