122 lines
3.1 KiB
C++
122 lines
3.1 KiB
C++
#pragma once
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#include "memory/pointer.h"
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#include "util/number.h"
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#include "util/utility.h"
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// Ported from legacy/CrackOS3 (include/features/optional.h), adapted to the
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// PrOSess freestanding environment: uses the in-tree move/forward (util/utility.h)
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// instead of <utility>. The CrackOS3 value_or_panic() helper is omitted because
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// there is no global panic() in this tree yet.
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template<typename T>
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struct optional {
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private:
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char buffer[sizeof(T)];
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bool initialized;
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void destroy() {
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if (initialized) {
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((T*)buffer)->~T();
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initialized = false;
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}
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}
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public:
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using value_type = T;
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constexpr optional() : initialized(false) {}
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optional(const T& value) : initialized(true) { new (buffer) T(value); }
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optional(T&& value) : initialized(true) { new (buffer) T(move(value)); }
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optional(const optional& other) : initialized(other.initialized) {
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if (initialized) {
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new (buffer) T(*other);
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}
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}
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optional(optional&& other) : initialized(other.initialized) {
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if (initialized) {
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new (buffer) T(move(*other));
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}
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other.initialized = false;
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}
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~optional() { destroy(); }
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T* operator->() { return (T*)buffer; }
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T& operator*() { return *((T*)buffer); }
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const T* operator->() const { return (const T*)buffer; }
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const T& operator*() const { return *((const T*)buffer); }
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optional& operator=(const optional& other) {
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if (this == &other)
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return *this;
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destroy();
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if (other.initialized) {
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new (buffer) T(*other);
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initialized = true;
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}
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return *this;
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}
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optional& operator=(optional&& other) noexcept {
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if (this == &other)
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return *this;
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destroy();
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if (other.initialized) {
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new (buffer) T(move(*other));
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initialized = true;
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}
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other.initialized = false;
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return *this;
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}
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[[nodiscard]] bool has_value() const { return initialized; }
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T& value() { return *((T*)buffer); }
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const T& value() const { return *((const T*)buffer); }
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template<typename Func, typename... ArgT>
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T value_or_create(Func func, ArgT... args) {
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if (initialized) {
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return value();
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} else {
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return func(args...);
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}
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}
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template<typename Func, typename... ArgT>
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T value_or_create(Func func, ArgT... args) const {
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if (initialized) {
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return value();
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} else {
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return func(args...);
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}
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}
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const T& value_or(const T& default_value) const {
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if (initialized) {
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return *((const T*)buffer);
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} else {
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return default_value;
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}
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}
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operator bool() const { return initialized; }
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bool operator!() const { return !initialized; }
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template<typename R, typename Func, typename... ArgT>
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optional<R> map(Func func, ArgT... args) {
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if (initialized) {
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return func(value(), forward<ArgT>(args)...);
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} else {
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return {};
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}
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}
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};
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