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File: basic_any.hpp
// Copyright Ruslan Arutyunyan, 2019-2021. // Copyright Antony Polukhin, 2021-2022. // // 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) // Contributed by Ruslan Arutyunyan #ifndef BOOST_ANYS_BASIC_ANY_HPP_INCLUDED #define BOOST_ANYS_BASIC_ANY_HPP_INCLUDED #include <boost/config.hpp> #ifdef BOOST_HAS_PRAGMA_ONCE # pragma once #endif #include <boost/any/bad_any_cast.hpp> #include <boost/any/fwd.hpp> #include <boost/assert.hpp> #include <boost/aligned_storage.hpp> #include <boost/type_index.hpp> #include <boost/type_traits/remove_reference.hpp> #include <boost/type_traits/decay.hpp> #include <boost/type_traits/remove_cv.hpp> #include <boost/type_traits/add_reference.hpp> #include <boost/type_traits/is_reference.hpp> #include <boost/type_traits/is_const.hpp> #include <boost/type_traits/is_nothrow_move_constructible.hpp> #include <boost/throw_exception.hpp> #include <boost/static_assert.hpp> #include <boost/utility/enable_if.hpp> #include <boost/core/addressof.hpp> #include <boost/type_traits/is_same.hpp> #include <boost/type_traits/conditional.hpp> namespace boost { namespace anys { template <std::size_t OptimizeForSize, std::size_t OptimizeForAlignment> class basic_any { BOOST_STATIC_ASSERT_MSG(OptimizeForSize > 0 && OptimizeForAlignment > 0, "Size and Align shall be positive values"); BOOST_STATIC_ASSERT_MSG(OptimizeForSize >= OptimizeForAlignment, "Size shall non less than Align"); BOOST_STATIC_ASSERT_MSG((OptimizeForAlignment & (OptimizeForAlignment - 1)) == 0, "Align shall be a power of 2"); BOOST_STATIC_ASSERT_MSG(OptimizeForSize % OptimizeForAlignment == 0, "Size shall be multiple of alignment"); private: enum operation { Destroy, Move, Copy, AnyCast, UnsafeCast, Typeinfo }; template <typename ValueType> static void* small_manager(operation op, basic_any& left, const basic_any* right, const boost::typeindex::type_info* info) { switch (op) { case Destroy: BOOST_ASSERT(!left.empty()); reinterpret_cast<ValueType*>(&left.content.small_value)->~ValueType(); break; case Move: { BOOST_ASSERT(left.empty()); BOOST_ASSERT(right); BOOST_ASSERT(!right->empty()); BOOST_ASSERT(right->type() == boost::typeindex::type_id<ValueType>()); ValueType* value = reinterpret_cast<ValueType*>(&const_cast<basic_any*>(right)->content.small_value); #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES new (&left.content.small_value) ValueType(std::move(*value)); #else new (&left.content.small_value) ValueType(*value); #endif left.man = right->man; reinterpret_cast<ValueType const*>(&right->content.small_value)->~ValueType(); const_cast<basic_any*>(right)->man = 0; }; break; case Copy: BOOST_ASSERT(left.empty()); BOOST_ASSERT(right); BOOST_ASSERT(!right->empty()); BOOST_ASSERT(right->type() == boost::typeindex::type_id<ValueType>()); new (&left.content.small_value) ValueType(*reinterpret_cast<const ValueType*>(&right->content.small_value)); left.man = right->man; break; case AnyCast: BOOST_ASSERT(info); BOOST_ASSERT(!left.empty()); return boost::typeindex::type_id<ValueType>() == *info ? reinterpret_cast<typename remove_cv<ValueType>::type *>(&left.content.small_value) : 0; case UnsafeCast: BOOST_ASSERT(!left.empty()); return reinterpret_cast<typename remove_cv<ValueType>::type *>(&left.content.small_value); case Typeinfo: return const_cast<void*>(static_cast<const void*>(&boost::typeindex::type_id<ValueType>().type_info())); } return 0; } template <typename ValueType> static void* large_manager(operation op, basic_any& left, const basic_any* right, const boost::typeindex::type_info* info) { switch (op) { case Destroy: BOOST_ASSERT(!left.empty()); delete static_cast<ValueType*>(left.content.large_value); break; case Move: BOOST_ASSERT(left.empty()); BOOST_ASSERT(right); BOOST_ASSERT(!right->empty()); BOOST_ASSERT(right->type() == boost::typeindex::type_id<ValueType>()); left.content.large_value = right->content.large_value; left.man = right->man; const_cast<basic_any*>(right)->content.large_value = 0; const_cast<basic_any*>(right)->man = 0; break; case Copy: BOOST_ASSERT(left.empty()); BOOST_ASSERT(right); BOOST_ASSERT(!right->empty()); BOOST_ASSERT(right->type() == boost::typeindex::type_id<ValueType>()); left.content.large_value = new ValueType(*static_cast<const ValueType*>(right->content.large_value)); left.man = right->man; break; case AnyCast: BOOST_ASSERT(info); BOOST_ASSERT(!left.empty()); return boost::typeindex::type_id<ValueType>() == *info ? static_cast<typename remove_cv<ValueType>::type *>(left.content.large_value) : 0; case UnsafeCast: BOOST_ASSERT(!left.empty()); return reinterpret_cast<typename remove_cv<ValueType>::type *>(left.content.large_value); case Typeinfo: return const_cast<void*>(static_cast<const void*>(&boost::typeindex::type_id<ValueType>().type_info())); } return 0; } template <typename ValueType> struct is_small_object : boost::integral_constant<bool, sizeof(ValueType) <= OptimizeForSize && boost::alignment_of<ValueType>::value <= OptimizeForAlignment && boost::is_nothrow_move_constructible<ValueType>::value> {}; template <typename ValueType> static void create(basic_any& any, const ValueType& value, boost::true_type) { typedef typename boost::decay<const ValueType>::type DecayedType; any.man = &small_manager<DecayedType>; new (&any.content.small_value) ValueType(value); } template <typename ValueType> static void create(basic_any& any, const ValueType& value, boost::false_type) { typedef typename boost::decay<const ValueType>::type DecayedType; any.man = &large_manager<DecayedType>; any.content.large_value = new DecayedType(value); } #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES template <typename ValueType> static void create(basic_any& any, ValueType&& value, boost::true_type) { typedef typename boost::decay<const ValueType>::type DecayedType; any.man = &small_manager<DecayedType>; new (&any.content.small_value) DecayedType(static_cast<ValueType&&>(value)); } template <typename ValueType> static void create(basic_any& any, ValueType&& value, boost::false_type) { typedef typename boost::decay<const ValueType>::type DecayedType; any.man = &large_manager<DecayedType>; any.content.large_value = new DecayedType(static_cast<ValueType&&>(value)); } #endif public: // non-type template parameters accessors static BOOST_CONSTEXPR_OR_CONST std::size_t buffer_size = OptimizeForSize; static BOOST_CONSTEXPR_OR_CONST std::size_t buffer_align = OptimizeForAlignment; public: // structors BOOST_CONSTEXPR basic_any() BOOST_NOEXCEPT : man(0), content() { } template<typename ValueType> basic_any(const ValueType & value) : man(0), content() { BOOST_STATIC_ASSERT_MSG( !(boost::is_same<ValueType, boost::any>::value), "boost::anys::basic_any shall not be constructed from boost::any" ); BOOST_STATIC_ASSERT_MSG( !anys::detail::is_basic_any<ValueType>::value, "boost::anys::basic_any<A, B> shall not be constructed from boost::anys::basic_any<C, D>" ); create(*this, value, is_small_object<ValueType>()); } basic_any(const basic_any & other) : man(0), content() { if (other.man) { other.man(Copy, *this, &other, 0); } } #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES // Move constructor basic_any(basic_any&& other) BOOST_NOEXCEPT : man(0), content() { if (other.man) { other.man(Move, *this, &other, 0); } } // Perfect forwarding of ValueType template<typename ValueType> basic_any(ValueType&& value , typename boost::disable_if<boost::is_same<basic_any&, ValueType> >::type* = 0 // disable if value has type `basic_any&` , typename boost::disable_if<boost::is_const<ValueType> >::type* = 0) // disable if value has type `const ValueType&&` : man(0), content() { typedef typename boost::decay<ValueType>::type DecayedType; BOOST_STATIC_ASSERT_MSG( !(boost::is_same<DecayedType, boost::any>::value), "boost::anys::basic_any shall not be constructed from boost::any" ); BOOST_STATIC_ASSERT_MSG( !anys::detail::is_basic_any<DecayedType>::value, "boost::anys::basic_any<A, B> shall not be constructed from boost::anys::basic_any<C, D>" ); create(*this, static_cast<ValueType&&>(value), is_small_object<DecayedType>()); } #endif ~basic_any() BOOST_NOEXCEPT { if (man) { man(Destroy, *this, 0, 0); } } public: // modifiers basic_any & swap(basic_any & rhs) BOOST_NOEXCEPT { if (this == &rhs) { return *this; } if (man && rhs.man) { basic_any tmp; rhs.man(Move, tmp, &rhs, 0); man(Move, rhs, this, 0); tmp.man(Move, *this, &tmp, 0); } else if (man) { man(Move, rhs, this, 0); } else if (rhs.man) { rhs.man(Move, *this, &rhs, 0); } return *this; } #ifdef BOOST_NO_CXX11_RVALUE_REFERENCES template<typename ValueType> basic_any & operator=(const ValueType & rhs) { BOOST_STATIC_ASSERT_MSG( !(boost::is_same<ValueType, boost::any>::value), "boost::any shall not be assigned into boost::anys::basic_any" ); BOOST_STATIC_ASSERT_MSG( !anys::detail::is_basic_any<ValueType>::value, "boost::anys::basic_any<A, B> shall not be assigned into boost::anys::basic_any<C, D>" ); basic_any(rhs).swap(*this); return *this; } basic_any & operator=(basic_any rhs) { rhs.swap(*this); return *this; } #else basic_any & operator=(const basic_any& rhs) { basic_any(rhs).swap(*this); return *this; } // move assignment basic_any & operator=(basic_any&& rhs) BOOST_NOEXCEPT { rhs.swap(*this); basic_any().swap(rhs); return *this; } // Perfect forwarding of ValueType template <class ValueType> basic_any & operator=(ValueType&& rhs) { typedef typename boost::decay<ValueType>::type DecayedType; BOOST_STATIC_ASSERT_MSG( !(boost::is_same<DecayedType, boost::any>::value), "boost::any shall not be assigned into boost::anys::basic_any" ); BOOST_STATIC_ASSERT_MSG( (!anys::detail::is_basic_any<DecayedType>::value || boost::is_same<DecayedType, basic_any>::value), "boost::anys::basic_any<A, B> shall not be assigned into boost::anys::basic_any<C, D>" ); basic_any(static_cast<ValueType&&>(rhs)).swap(*this); return *this; } #endif public: // queries bool empty() const BOOST_NOEXCEPT { return !man; } void clear() BOOST_NOEXCEPT { basic_any().swap(*this); } const boost::typeindex::type_info& type() const BOOST_NOEXCEPT { return man ? *static_cast<const boost::typeindex::type_info*>(man(Typeinfo, const_cast<basic_any&>(*this), 0, 0)) : boost::typeindex::type_id<void>().type_info(); } private: // representation template<typename ValueType, std::size_t Size, std::size_t Alignment> friend ValueType * any_cast(basic_any<Size, Alignment> *) BOOST_NOEXCEPT; template<typename ValueType, std::size_t Size, std::size_t Alignment> friend ValueType * unsafe_any_cast(basic_any<Size, Alignment> *) BOOST_NOEXCEPT; typedef void*(*manager)(operation op, basic_any& left, const basic_any* right, const boost::typeindex::type_info* info); manager man; union content { void * large_value; typename boost::aligned_storage<OptimizeForSize, OptimizeForAlignment>::type small_value; } content; }; template<std::size_t OptimizeForSize, std::size_t OptimizeForAlignment> void swap(basic_any<OptimizeForSize, OptimizeForAlignment>& lhs, basic_any<OptimizeForSize, OptimizeForAlignment>& rhs) BOOST_NOEXCEPT { lhs.swap(rhs); } template<typename ValueType, std::size_t Size, std::size_t Alignment> ValueType * any_cast(basic_any<Size, Alignment> * operand) BOOST_NOEXCEPT { return operand->man ? static_cast<typename remove_cv<ValueType>::type *>(operand->man(basic_any<Size, Alignment>::AnyCast, *operand, 0, &boost::typeindex::type_id<ValueType>().type_info())) : 0; } template<typename ValueType, std::size_t OptimizeForSize, std::size_t OptimizeForAlignment> inline const ValueType * any_cast(const basic_any<OptimizeForSize, OptimizeForAlignment> * operand) BOOST_NOEXCEPT { return any_cast<ValueType>(const_cast<basic_any<OptimizeForSize, OptimizeForAlignment> *>(operand)); } template<typename ValueType, std::size_t OptimizeForSize, std::size_t OptimizeForAlignment> ValueType any_cast(basic_any<OptimizeForSize, OptimizeForAlignment> & operand) { typedef typename remove_reference<ValueType>::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 // `ValueType` is not a reference. Example: // `static_cast<std::string>(*result);` // which is equal to `std::string(*result);` typedef typename boost::conditional< boost::is_reference<ValueType>::value, ValueType, typename boost::add_reference<ValueType>::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 ValueType, std::size_t OptimizeForSize, std::size_t OptimizeForAlignment> inline ValueType any_cast(const basic_any<OptimizeForSize, OptimizeForAlignment> & operand) { typedef typename remove_reference<ValueType>::type nonref; return any_cast<const nonref &>(const_cast<basic_any<OptimizeForSize, OptimizeForAlignment> &>(operand)); } #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES template<typename ValueType, std::size_t OptimizeForSize, std::size_t OptimizeForAlignment> inline ValueType any_cast(basic_any<OptimizeForSize, OptimizeForAlignment>&& operand) { BOOST_STATIC_ASSERT_MSG( boost::is_rvalue_reference<ValueType&&>::value /*true if ValueType is rvalue or just a value*/ || boost::is_const< typename boost::remove_reference<ValueType>::type >::value, "boost::any_cast shall not be used for getting nonconst references to temporary objects" ); return any_cast<ValueType>(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 ValueType, std::size_t OptimizedForSize, std::size_t OptimizeForAlignment> inline ValueType * unsafe_any_cast(basic_any<OptimizedForSize, OptimizeForAlignment> * operand) BOOST_NOEXCEPT { return static_cast<ValueType*>(operand->man(basic_any<OptimizedForSize, OptimizeForAlignment>::UnsafeCast, *operand, 0, 0)); } template<typename ValueType, std::size_t OptimizeForSize, std::size_t OptimizeForAlignment> inline const ValueType * unsafe_any_cast(const basic_any<OptimizeForSize, OptimizeForAlignment> * operand) BOOST_NOEXCEPT { return unsafe_any_cast<ValueType>(const_cast<basic_any<OptimizeForSize, OptimizeForAlignment> *>(operand)); } } // namespace anys using boost::anys::any_cast; using boost::anys::unsafe_any_cast; } // namespace boost #endif // #ifndef BOOST_ANYS_BASIC_ANY_HPP_INCLUDED