CppNet/base/Any.h

#ifndef HEADER_BASE_CANY
#define HEADER_BASE_CANY

#include <typeinfo>
#include <algorithm>

namespace base {
    class CAny {
    public:
        CAny() noexcept : _content(0) {}

        template<typename ValueType>
        CAny(const ValueType & value) : _content(new CHolder<ValueType>(value)) {}

        CAny(const CAny & other) : _content(other._content ? other._content->Clone() : 0) {}

        CAny(CAny&& other) noexcept : _content(other._content) {
            other._content = 0;
        }

        ~CAny() noexcept {
            delete _content;
        }

    public: // modifiers
        CAny& Swap(CAny & rhs) noexcept {
            std::swap(_content, rhs._content);
            return *this;
        }

        template<typename ValueType>
        CAny& operator=(const ValueType & rhs) {
            CAny(rhs).Swap(*this);
            return *this;
        }

        CAny& operator=(CAny rhs) {
            CAny(rhs).Swap(*this);
            return *this;
        }

        // move assignement
        CAny& operator=(CAny&& rhs) noexcept {
            rhs.Swap(*this);
            CAny().Swap(rhs);
            return *this;
        }

    public: // queries
        bool Empty() const noexcept {
            return !_content;
        }

        void Clear() noexcept {
            CAny().Swap(*this);
        }

        const std::type_info& Type() const noexcept {
            return _content ? _content->Type() : typeid(void);
        }

        class CPlaceHolder {
        public:
            virtual ~CPlaceHolder() {
            }

            // queries
            virtual const std::type_info& Type() const noexcept = 0;
            virtual CPlaceHolder * Clone() const = 0;
        };

        template<typename ValueType>
        class CHolder : public CPlaceHolder {
        public:
            CHolder(const ValueType& value) : _held(value) {
            }

            CHolder(ValueType&& value) : _held(static_cast<ValueType&&>(value)) {
            }

            // queries
            virtual const std::type_info& Type() const noexcept {
                return typeid(ValueType);
            }
            virtual CPlaceHolder * Clone() const {
                return new CHolder(_held);
            }

        public:
            ValueType _held;

        private:
            CHolder & operator=(const CHolder&) {}
        };

    private: // representation
        template<typename ValueType>
        friend ValueType* any_cast(CAny *) noexcept;

        CPlaceHolder* _content;
    };
    
        class bad_any_cast: public std::exception {
    public:
        virtual const char * what() const noexcept {
            return "bad_any_cast : failed conversion using any_cast";
        }
    };
    
    template<typename ValueType>
    ValueType* any_cast(CAny * operand) noexcept {
    if (operand && operand->Type() == typeid(ValueType)) {
        return &static_cast<CAny::CHolder<ValueType> *>(operand->_content)->_held;
    }
    return nullptr;
}
    
    template<typename ValueType>
    const ValueType * any_cast(const CAny * operand) noexcept {
        return any_cast<ValueType>(const_cast<CAny *>(operand));
    }
    
    template<typename ValueType>
    ValueType any_cast(CAny & operand) {
        ValueType * result = any_cast<ValueType>(&operand);
        if (!result)
            std::exception(bad_any_cast());

        return static_cast<ValueType>(*result);
    }
    
    template<typename ValueType>
    inline ValueType any_cast(const CAny& operand) {
        return any_cast<const ValueType&>(const_cast<CAny&>(operand));
    }
    
    template<typename ValueType>
        inline ValueType any_cast(CAny&& operand) {
        return any_cast<ValueType>(operand);
    }
}

#endif