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