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- #ifndef BOOST_LEAF_DETAIL_OPTIONAL_HPP_INCLUDED
- #define BOOST_LEAF_DETAIL_OPTIONAL_HPP_INCLUDED
- // Copyright 2018-2023 Emil Dotchevski and Reverge Studios, Inc.
- // Distributed under the Boost Software License, Version 1.0. (See accompanying
- // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- #include <boost/leaf/config.hpp>
- #include <utility>
- #include <new>
- namespace boost { namespace leaf {
- namespace leaf_detail
- {
- template <class T>
- class optional
- {
- int key_;
- union { T value_; };
- public:
- typedef T value_type;
- BOOST_LEAF_CONSTEXPR optional() noexcept:
- key_(0)
- {
- }
- BOOST_LEAF_CONSTEXPR optional( optional const & x ):
- key_(x.key_)
- {
- if( x.key_ )
- (void) new (&value_) T( x.value_ );
- }
- BOOST_LEAF_CONSTEXPR optional( optional && x ) noexcept:
- key_(x.key_)
- {
- if( x.key_ )
- {
- (void) new (&value_) T( std::move(x.value_) );
- x.reset();
- }
- }
- BOOST_LEAF_CONSTEXPR optional( int key, T const & v ):
- key_(key),
- value_(v)
- {
- BOOST_LEAF_ASSERT(!empty());
- }
- BOOST_LEAF_CONSTEXPR optional( int key, T && v ) noexcept:
- key_(key),
- value_(std::move(v))
- {
- BOOST_LEAF_ASSERT(!empty());
- }
- BOOST_LEAF_CONSTEXPR optional & operator=( optional const & x )
- {
- reset();
- if( int key = x.key() )
- {
- load(key, x.value_);
- key_ = key;
- }
- return *this;
- }
- BOOST_LEAF_CONSTEXPR optional & operator=( optional && x ) noexcept
- {
- reset();
- if( int key = x.key() )
- {
- load(key, std::move(x.value_));
- x.reset();
- }
- return *this;
- }
- ~optional() noexcept
- {
- reset();
- }
- BOOST_LEAF_CONSTEXPR bool empty() const noexcept
- {
- return key_==0;
- }
- BOOST_LEAF_CONSTEXPR int key() const noexcept
- {
- return key_;
- }
- BOOST_LEAF_CONSTEXPR void reset() noexcept
- {
- if( key_ )
- {
- value_.~T();
- key_=0;
- }
- }
- BOOST_LEAF_CONSTEXPR T & load( int key )
- {
- BOOST_LEAF_ASSERT(key);
- reset();
- (void) new(&value_) T;
- key_=key;
- return value_;
- }
- BOOST_LEAF_CONSTEXPR T & load( int key, T const & v )
- {
- BOOST_LEAF_ASSERT(key);
- reset();
- (void) new(&value_) T(v);
- key_=key;
- return value_;
- }
- BOOST_LEAF_CONSTEXPR T & load( int key, T && v ) noexcept
- {
- BOOST_LEAF_ASSERT(key);
- reset();
- (void) new(&value_) T(std::move(v));
- key_=key;
- return value_;
- }
- BOOST_LEAF_CONSTEXPR T const * has_value(int key) const noexcept
- {
- BOOST_LEAF_ASSERT(key);
- return key_==key ? &value_ : nullptr;
- }
- BOOST_LEAF_CONSTEXPR T * has_value(int key) noexcept
- {
- BOOST_LEAF_ASSERT(key);
- return key_==key ? &value_ : nullptr;
- }
- BOOST_LEAF_CONSTEXPR T const & value(int key) const & noexcept
- {
- BOOST_LEAF_ASSERT(has_value(key) != 0);
- (void) key;
- return value_;
- }
- BOOST_LEAF_CONSTEXPR T & value(int key) & noexcept
- {
- BOOST_LEAF_ASSERT(has_value(key) != 0);
- (void) key;
- return value_;
- }
- BOOST_LEAF_CONSTEXPR T const && value(int key) const && noexcept
- {
- BOOST_LEAF_ASSERT(has_value(key) != 0);
- (void) key;
- return value_;
- }
- BOOST_LEAF_CONSTEXPR T value(int key) && noexcept
- {
- BOOST_LEAF_ASSERT(has_value(key) != 0);
- (void) key;
- T tmp(std::move(value_));
- reset();
- return tmp;
- }
- };
- }
- } }
- #endif
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