mirror of https://github.com/bsnes-emu/bsnes.git
77 lines
2.6 KiB
C++
77 lines
2.6 KiB
C++
#ifndef NALL_MAYBE_HPP
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#define NALL_MAYBE_HPP
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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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class maybe {
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T* value = nullptr;
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public:
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maybe() {}
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maybe(nothing_t) {}
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maybe(const T& source) { operator=(source); }
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maybe(const maybe& source) { operator=(source); }
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maybe(maybe&& source) { operator=(std::move(source)); }
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~maybe() { reset(); }
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maybe& operator=(nothing_t) { reset(); return *this; }
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maybe& operator=(const T& source) { reset(); value = new T(source); return *this; }
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maybe& operator=(const maybe& source) { reset(); if(source) value = new T(source()); return *this; }
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maybe& operator=(maybe&& source) { reset(); value = source.value; source.value = nullptr; return *this; }
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bool operator==(const maybe& source) const {
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if(value && source.value) return *value == *source.value;
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return !value && !source.value;
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}
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bool operator!=(const maybe& source) const { return !operator==(source); }
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explicit operator bool() const { return value; }
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T& operator()() { assert(value); return *value; }
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const T& operator()() const { assert(value); return *value; }
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const T& operator()(const T& invalid) const { if(value) return *value; return invalid; }
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bool empty() const { return value == nullptr; }
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void reset() { if(value) { delete value; value = nullptr; } }
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void swap(maybe& source) { std::swap(value, source.value); }
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};
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template<typename T>
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class maybe<T&> {
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T* value = nullptr;
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public:
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maybe() {}
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maybe(nothing_t) {}
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maybe(const T& source) { operator=(source); }
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maybe(const maybe& source) { operator=(source); }
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maybe(maybe&& source) { operator=(std::move(source)); }
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maybe& operator=(nothing_t) { value = nullptr; return *this; }
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maybe& operator=(const T& source) { value = (T*)&source; return *this; }
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maybe& operator=(const maybe& source) { value = source.value; return *this; }
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maybe& operator=(maybe&& source) { value = source.value; source.value = nullptr; return *this; }
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bool operator==(const maybe& source) const {
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if(value && source.value) return *value == *source.value;
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return !value && !source.value;
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}
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bool operator!=(const maybe& source) const { return !operator==(source); }
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explicit operator bool() const { return value; }
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T& operator()() { assert(value); return *value; }
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const T& operator()() const { assert(value); return *value; }
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const T& operator()(const T& invalid) const { if(value) return *value; return invalid; }
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bool empty() const { return value == nullptr; }
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void reset() { value = nullptr; }
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void swap(maybe& source) { std::swap(value, source.value); }
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};
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}
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#endif
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