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68 lines
1.7 KiB
C++
68 lines
1.7 KiB
C++
#pragma once
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#include "vcpkg_Checks.h"
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namespace vcpkg
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{
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struct NullOpt
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{
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explicit constexpr NullOpt(int) {}
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};
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const static constexpr NullOpt nullopt{ 0 };
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template<class T>
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class Optional
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{
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public:
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constexpr Optional() : m_is_present(false), m_t() {}
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// Constructors are intentionally implicit
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constexpr Optional(NullOpt) : m_is_present(false), m_t() {}
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Optional(const T& t) : m_is_present(true), m_t(t) {}
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Optional(T&& t) : m_is_present(true), m_t(std::move(t)) {}
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T&& value_or_exit(const LineInfo& line_info) &&
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{
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this->exit_if_null(line_info);
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return std::move(this->m_t);
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}
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const T& value_or_exit(const LineInfo& line_info) const &
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{
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this->exit_if_null(line_info);
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return this->m_t;
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}
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constexpr explicit operator bool() const { return this->m_is_present; }
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constexpr bool has_value() const { return m_is_present; }
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template<class U>
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T value_or(U&& default_value) const &
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{
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return bool(*this) ? this->m_t : static_cast<T>(std::forward<U>(default_value));
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}
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template<class U>
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T value_or(U&& default_value) &&
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{
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return bool(*this) ? std::move(this->m_t) : static_cast<T>(std::forward<U>(default_value));
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}
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const T* get() const { return bool(*this) ? &this->m_t : nullptr; }
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T* get() { return bool(*this) ? &this->m_t : nullptr; }
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private:
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void exit_if_null(const LineInfo& line_info) const
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{
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Checks::check_exit(line_info, this->m_is_present, "Value was null");
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}
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bool m_is_present;
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T m_t;
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};
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}
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