source: trunk/legacy/any.hh @ 502

// Copyright (C) 2014-2015 ChaosForge Ltd
// http://chaosforge.org/
//
// This file is part of Nova libraries. 
// For conditions of distribution and use, see copying.txt file in root folder.

/**
 * @file any.hh
 * @author Kornel Kisielewicz
 * @brief any type
 *
 * based on http://www.two-sdg.demon.co.uk/curbralan/papers/ValuedConversions.pdf
 */

#ifndef NV_STL_ANY_HH
#define NV_STL_ANY_HH

#include <nv/common.hh>
#include <nv/stl/utility.hh>
#include <nv/stl/type_traits.hh>
#include <nv/stl/type_info.hh>

#error "any type is currently unsupported!"

namespace nv
{
        
        class any
        {
        public:
                any() : m_content( nullptr ) {}
                
                any( const any& other )
                        : m_content( other.m_content ? other.m_content->clone() : nullptr )
                {}

                template< typename T >
                any( const T& value )
                        : m_content( new holder<T>( value ) )
                {}

                any( any&& other ) 
                        : m_content( other.m_content )
                {}

                template< typename T >
                any( T&& value )
                        : m_content( new holder<T>( forward<T>(value) ) )
                {}

                ~any() 
                { 
                        delete m_content; 
                }

                any& swap( any& rhs )
                {
                        nv::swap( m_content, rhs.m_content );
                        return *this;
                }

                any& operator=( const any& rhs )
                {
                        return swap( any( rhs ) );
                }

                any& operator=( any&& rhs )
                {
                        swap( rhs );
                        any().swap( rhs );
                        return *this;
                }

                template < typename T >
                any& operator= ( T&& rhs )
                {
                        any( forward<T>(rhs) ).swap(*this);
                        return *this;
                }

                operator const void* () const
                {
                        return m_content;
                }

                template< typename T >
                bool copy_to( T& value ) const
                {
                        const T* copyable = to_ptr<T>();
                        if ( copyable ) value = *copyable;
                        return copyable;
                }
                template< typename T >
                const T* to_ptr() const
                {
                        return type_info() == typeid(T) ? &static_cast< holder<T> *>(m_content)->held                           : nullptr;
                }

                bool empty() const
                {
                        return !m_content;
                }

                void clear()
                {
                        any().swap(*this);
                }

                const std::type_info &type_info() const
                {
                        return m_content ? m_content->type_info() : typeid(void);
                }
        private:
                class placeholder
                {
                public:
                        virtual const std::type_info& type_info() const = 0;
                        virtual placeholder *clone() const = 0;
                        virtual ~placeholder() {}
                };

                template< typename T >
                class holder : public placeholder
                {
                public:
                        holder( const T& value ) : held(value)
                        {
                        }
                        holder( T&& value ) : held(forward<T>(value))
                        {
                        }
                        virtual const std::type_info &type_info() const
                        {
                                return typeid(T);
                        }
                        virtual placeholder *clone() const
                        {
                                return new holder(held);
                        }
                        const T held;
                };
                placeholder *m_content;
        };

        inline void swap( any& lhs, any& rhs )
        {
                lhs.swap(rhs);
        }

        template< typename T >
        T any_cast( const any& operand )
        {
                const T* result = operand.to_ptr<T>();
                return result ? *result : throw std::bad_cast();
        }
}

#endif // NV_STL_ANY_HH