102 lines
2.9 KiB
C++
102 lines
2.9 KiB
C++
/*
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Copyright (c) 2013 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#pragma once
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#include "util/debug.h"
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namespace lean {
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/**
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\brief Simple optional template. This is a naive replacement for C++14 optional.
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We will delete it as soon optional is supported in g++ and clang++.
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*/
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template<typename T>
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class optional {
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bool m_some;
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union {
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T m_value;
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};
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public:
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optional():m_some(false) {}
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optional(T const & v):m_some(true) {
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new (&m_value) T(v);
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}
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optional(optional const & other):m_some(other.m_some) {
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if (m_some)
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new (&m_value) T(other.m_value);
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}
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optional(optional && other):m_some(other.m_some) {
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if (m_some)
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new (&m_value) T(std::forward<T>(other.m_value));
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}
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template<typename... Args>
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optional(Args&&... args):m_some(true) {
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new (&m_value) T(args...);
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}
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~optional() {
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if (m_some)
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m_value.~T();
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}
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operator bool() const { return m_some; }
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T const * operator->() const { lean_assert(m_some); return &m_value; }
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T * operator->() { lean_assert(m_some); return &m_value; }
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T const & operator*() const { lean_assert(m_some); return m_value; }
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T & operator*() { lean_assert(m_some); return m_value; }
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T const & value() const { lean_assert(m_some); return m_value; }
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T & value() { lean_assert(m_some); return m_value; }
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template<typename... Args>
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void emplace(Args&&... args) {
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if (m_some)
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m_value.~T();
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new (&m_value) T(args...);
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}
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optional& operator=(optional const & other) {
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if (this == &other)
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return *this;
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if (m_some)
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m_value.~T();
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m_some = other.m_some;
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if (m_some)
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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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lean_assert(this != &other);
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if (m_some)
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m_value.~T();
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m_some = other.m_some;
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if (m_some)
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new (&m_value) T(std::forward<T>(other.m_value));
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return *this;
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}
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optional& operator=(T const & other) {
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if (m_some)
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m_value.~T();
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m_some = true;
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new (&m_value) T(other);
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return *this;
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}
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optional& operator=(T && other) {
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if (m_some)
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m_value.~T();
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m_some = true;
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new (&m_value) T(std::forward<T>(other));
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return *this;
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}
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friend bool operator==(optional const & o1, optional const & o2) {
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if (o1.m_some != o2.m_some)
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return false;
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else
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return !o1.m_some || o1.m_value == o2.m_value;
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}
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};
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template<typename T> optional<T> some(T const & t) { return optional<T>(t); }
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template<typename T> optional<T> some(T && t) { return optional<T>(std::forward<T>(t)); }
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}
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