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- // Copyright Antony Polukhin, 2020-2023.
- //
- // 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)
- // See http://www.boost.org/libs/any for Documentation.
- #ifndef BOOST_ANYS_UNIQUE_ANY_HPP_INCLUDED
- #define BOOST_ANYS_UNIQUE_ANY_HPP_INCLUDED
- #include <boost/config.hpp>
- #ifdef BOOST_HAS_PRAGMA_ONCE
- # pragma once
- #endif
- #ifdef BOOST_NO_CXX11_RVALUE_REFERENCES
- #error Header <boost/any/unique_any.hpp> requires C++11 compatible compiler with move semantics
- #endif
- #ifdef BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
- #error Header <boost/any/unique_any.hpp> requires C++11 compatible compiler with defaulted functions
- #endif
- #ifdef BOOST_NO_CXX11_SMART_PTR
- #error Header <boost/any/unique_any.hpp> requires C++11 compatible standard library with std::unique_ptr
- #endif
- #include <memory>
- #ifdef BOOST_NO_CXX11_HDR_INITIALIZER_LIST
- #include <initializer_list>
- #endif
- #include <utility>
- #include <boost/any/bad_any_cast.hpp>
- #include <boost/core/addressof.hpp>
- #include <boost/type_traits/decay.hpp>
- namespace boost { namespace anys {
- template <class T>
- struct in_place_type_t
- {
- };
- #if !defined(BOOST_NO_CXX14_VARIABLE_TEMPLATES)
- template <class T>
- constexpr in_place_type_t<T> in_place_type{};
- #endif
- class unique_any {
- public:
- BOOST_CONSTEXPR unique_any() BOOST_NOEXCEPT = default;
- unique_any(unique_any&& other) BOOST_NOEXCEPT = default;
- // Perfect forwarding of T
- template<typename T>
- unique_any(T&& value
- , typename boost::disable_if<boost::is_same<unique_any&, T> >::type* = 0 // disable if value has type `unique_any&`
- , typename boost::disable_if<boost::is_const<T> >::type* = 0) // disable if value has type `const T&&`
- : content(new holder< typename boost::decay<T>::type >(std::forward<T>(value)))
- {
- }
- template<class T, class... Args>
- explicit unique_any(in_place_type_t<T>, Args&&... args)
- : content(new holder<typename boost::decay<T>::type>(std::forward<Args>(args)...))
- {
- }
- #ifdef BOOST_NO_CXX11_HDR_INITIALIZER_LIST
- template <class T, class U, class... Args>
- explicit unique_any(in_place_type_t<T>, std::initializer_list<U> il, Args&&... args)
- : content(new holder<typename boost::decay<T>::type>(il, std::forward<Args>(args)...))
- {
- }
- #endif
- ~unique_any() BOOST_NOEXCEPT = default;
- unique_any & operator=(unique_any&& rhs) BOOST_NOEXCEPT = default;
- template <class T>
- unique_any & operator=(T&& rhs)
- {
- unique_any(std::forward<T>(rhs)).swap(*this);
- return *this;
- }
- template<class T, class... Args>
- typename boost::decay<T>::type& emplace(Args&&... args) {
- content = std::unique_ptr<placeholder>(
- new holder<typename boost::decay<T>::type>(std::forward<Args>(args)...)
- );
- }
- #ifdef BOOST_NO_CXX11_HDR_INITIALIZER_LIST
- template<class T, class U, class... Args>
- typename boost::decay<T>::type& emplace(initializer_list<U> il, Args&&... args) {
- content = std::unique_ptr<placeholder>(
- new holder<typename boost::decay<T>::type>(il, std::forward<Args>(args)...)
- );
- }
- #endif
- void reset() BOOST_NOEXCEPT
- {
- content.reset();
- }
- unique_any& swap(unique_any& rhs) BOOST_NOEXCEPT
- {
- content.swap(rhs.content);
- return *this;
- }
- bool has_value() const BOOST_NOEXCEPT
- {
- return !content;
- }
- const boost::typeindex::type_info& type() const BOOST_NOEXCEPT
- {
- return content ? content->type() : boost::typeindex::type_id<void>().type_info();
- }
- private: // types
- class BOOST_SYMBOL_VISIBLE placeholder
- {
- virtual ~placeholder()
- {
- }
- virtual const boost::typeindex::type_info& type() const BOOST_NOEXCEPT = 0;
- };
- template<typename T>
- class holder BOOST_FINAL: public placeholder
- {
- public: // structors
- template <class... Args>
- holder(Args&&... args)
- : held(std::forward<Args>(args)...)
- {
- }
- #ifdef BOOST_NO_CXX11_HDR_INITIALIZER_LIST
- template <class U, class... Args>
- holder(std::initializer_list<U> il, Args&&... args)
- : held(il, std::forward<Args>(args)...)
- {
- }
- #endif
- const boost::typeindex::type_info& type() const BOOST_NOEXCEPT BOOST_OVERRIDE
- {
- return boost::typeindex::type_id<T>().type_info();
- }
- public: // representation
- T held;
- };
- private: // representation
- template<typename T>
- friend T * any_cast(unique_any *) BOOST_NOEXCEPT;
- template<typename T>
- friend T * unsafe_any_cast(unique_any *) BOOST_NOEXCEPT;
- std::unique_ptr<placeholder> content;
- };
- inline void swap(unique_any & lhs, unique_any & rhs) BOOST_NOEXCEPT
- {
- lhs.swap(rhs);
- }
- template<typename T>
- T * any_cast(unique_any * operand) BOOST_NOEXCEPT
- {
- return operand && operand->type() == boost::typeindex::type_id<T>()
- ? boost::addressof(
- static_cast<unique_any::holder<BOOST_DEDUCED_TYPENAME remove_cv<T>::type>&>(*operand->content).held
- )
- : 0;
- }
- template<typename T>
- inline const T * any_cast(const unique_any * operand) BOOST_NOEXCEPT
- {
- return any_cast<T>(const_cast<unique_any *>(operand));
- }
- template<typename T>
- T any_cast(unique_any & operand)
- {
- typedef BOOST_DEDUCED_TYPENAME remove_reference<T>::type nonref;
- nonref * result = any_cast<nonref>(boost::addressof(operand));
- if(!result)
- boost::throw_exception(bad_any_cast());
- // Attempt to avoid construction of a temporary object in cases when
- // `T` is not a reference. Example:
- // `static_cast<std::string>(*result);`
- // which is equal to `std::string(*result);`
- typedef BOOST_DEDUCED_TYPENAME boost::conditional<
- boost::is_reference<T>::value,
- T,
- BOOST_DEDUCED_TYPENAME boost::add_reference<T>::type
- >::type ref_type;
- #ifdef BOOST_MSVC
- # pragma warning(push)
- # pragma warning(disable: 4172) // "returning address of local variable or temporary" but *result is not local!
- #endif
- return static_cast<ref_type>(*result);
- #ifdef BOOST_MSVC
- # pragma warning(pop)
- #endif
- }
- template<typename T>
- inline T any_cast(const unique_any & operand)
- {
- typedef BOOST_DEDUCED_TYPENAME remove_reference<T>::type nonref;
- return any_cast<const nonref &>(const_cast<unique_any &>(operand));
- }
- #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
- template<typename T>
- inline T any_cast(unique_any&& operand)
- {
- BOOST_STATIC_ASSERT_MSG(
- boost::is_rvalue_reference<T&&>::value /*true if T is rvalue or just a value*/
- || boost::is_const< typename boost::remove_reference<T>::type >::value,
- "boost::any_cast shall not be used for getting nonconst references to temporary objects"
- );
- return any_cast<T>(operand);
- }
- #endif
- // Note: The "unsafe" versions of any_cast are not part of the
- // public interface and may be removed at any time. They are
- // required where we know what type is stored in the any and can't
- // use typeid() comparison, e.g., when our types may travel across
- // different shared libraries.
- template<typename T>
- inline T * unsafe_any_cast(unique_any * operand) BOOST_NOEXCEPT
- {
- return boost::addressof(
- static_cast<unique_any::holder<T>&>(*operand->content)->held
- );
- }
- template<typename T>
- inline const T * unsafe_any_cast(const unique_any * operand) BOOST_NOEXCEPT
- {
- return unsafe_any_cast<T>(const_cast<unique_any *>(operand));
- }
- } // namespace anys
- using boost::anys::any_cast;
- using boost::anys::unsafe_any_cast;
- } // namespace boost
- #endif // BOOST_ANYS_UNIQUE_ANY_HPP_INCLUDED
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