78 lines
1.6 KiB
C++
78 lines
1.6 KiB
C++
#ifndef optional_hh_INCLUDED
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#define optional_hh_INCLUDED
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namespace Kakoune
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{
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template<typename T>
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struct Optional
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{
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public:
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constexpr Optional() : m_valid(false) {}
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Optional(const T& other) : m_valid(true) { new (&m_value) T(other); }
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Optional(T&& other) : m_valid(true) { new (&m_value) T(std::move(other)); }
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Optional(const Optional& other)
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: m_valid(other.m_valid)
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{
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if (m_valid)
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new (&m_value) T(other.m_value);
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}
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Optional(Optional&& other)
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: m_valid(other.m_valid)
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{
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if (m_valid)
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new (&m_value) T(std::move(other.m_value));
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}
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Optional& operator=(const Optional& other)
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{
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if (m_valid)
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m_value.~T();
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if ((m_valid = other.m_valid))
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new (&m_value) T(other.m_value);
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return *this;
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}
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Optional& operator=(Optional&& other)
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{
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if (m_valid)
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m_value.~T();
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if ((m_valid = other.m_valid))
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new (&m_value) T(std::move(other.m_value));
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return *this;
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}
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~Optional()
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{
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if (m_valid)
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m_value.~T();
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}
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constexpr explicit operator bool() const noexcept { return m_valid; }
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T& operator*()
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{
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kak_assert(m_valid);
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return m_value;
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}
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const T& operator*() const { return *const_cast<Optional&>(*this); }
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T* operator->()
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{
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kak_assert(m_valid);
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return &m_value;
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}
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const T* operator->() const { return const_cast<Optional&>(*this).operator->(); }
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private:
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bool m_valid;
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union { T m_value; };
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};
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}
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#endif // optional_hh_INCLUDED
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