source: downloads/ogre_src_v1-9-0/OgreMain/include/OgreMemorySTLAllocator.h

/*
-----------------------------------------------------------------------------
This source file is part of OGRE
(Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2013 Torus Knot Software Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-----------------------------------------------------------------------------
*/

#ifndef _MemorySTLAllocator_H__
#define _MemorySTLAllocator_H__

#include "OgrePrerequisites.h"
#include "OgreHeaderPrefix.h"

namespace Ogre
{


        /** \addtogroup Core
        *  @{
        */
        /** \addtogroup Memory
        *  @{
        */
        /**
        Wrapper class for operating as an STL container allocator.
        This class acts as the host for a configured allocation policy.

        It takes the following template parameters:-
        <ul>
        <li>T                   : the type we will be allocating (see rebind later)</li>
        <li>AllocPolicy : a memory allocator policy </li>
        </ul>

        See StdAllocPolicy for an example of implementing a Policy. The reason for
        implementing the allocation in a policy is that it makes implementing
        a custom allocator easier -  you just have to provide an alternative
        policy with just allocate/deallocate implementations; this class does all the
        housekeeping associated with keeping the STL happy.
        */

        // Base STL allocator class.
        template<typename T>
        struct STLAllocatorBase
        {       // base class for generic allocators
                typedef T value_type;
        };

        // Base STL allocator class. (const T version).
        template<typename T>
        struct STLAllocatorBase<const T>
        {       // base class for generic allocators for const T
                typedef T value_type;
        };

        template
                <
                typename T,
                typename AllocPolicy
                >
        class STLAllocator : public STLAllocatorBase<T>
        {
        public :
                /// define our types, as per ISO C++
                typedef STLAllocatorBase<T>                     Base;
                typedef typename Base::value_type       value_type;
                typedef value_type*                                     pointer;
                typedef const value_type*                       const_pointer;
                typedef value_type&                                     reference;
                typedef const value_type&                       const_reference;
                typedef std::size_t                                     size_type;
                typedef std::ptrdiff_t                          difference_type;


                /// the standard rebind mechanism
                template<typename U>
                struct rebind
                {
                        typedef STLAllocator<U, AllocPolicy> other;
                };

                /// ctor
                inline explicit STLAllocator()
                { }

                /// dtor
                virtual ~STLAllocator()
                { }

                /// copy ctor - done component wise
                inline STLAllocator( STLAllocator const& )
                { }

                /// cast
                template <typename U>
                inline STLAllocator( STLAllocator<U, AllocPolicy> const& )
                { }

                /// cast
                template <typename U, typename P>
                inline STLAllocator( STLAllocator<U, P> const& )
                { }

                /// memory allocation (elements, used by STL)
                inline pointer allocate( size_type count,
                        typename std::allocator<void>::const_pointer ptr = 0 )
                {
                        (void)ptr;
                        // convert request to bytes
                        register size_type sz = count*sizeof( T );
                        pointer p  = static_cast<pointer>(AllocPolicy::allocateBytes(sz));
                        return p;
                }

                /// memory deallocation (elements, used by STL)
                inline void deallocate( pointer ptr, size_type )
                {
                        // convert request to bytes, but we can't use this?
                        // register size_type sz = count*sizeof( T );
                        AllocPolicy::deallocateBytes(ptr);
                }

                pointer address(reference x) const
                {
                        return &x;
                }

                const_pointer address(const_reference x) const
                {
                        return &x;
                }

                size_type max_size() const throw()
                {
                        // maximum size this can handle, delegate
                        return AllocPolicy::getMaxAllocationSize();
                }

#if __cplusplus < 201103L
                void construct(pointer p)
                {
                        // call placement new
                        new(static_cast<void*>(p)) T();
                }
#endif

                void construct(pointer p, const T& val)
                {
                        // call placement new
                        new(static_cast<void*>(p)) T(val);
                }

                void destroy(pointer p)
                {
                        // do we have to protect against non-classes here?
                        // some articles suggest yes, some no
                        p->~T();
                }
        };

        /// determine equality, can memory from another allocator
        /// be released by this allocator, (ISO C++)
        template<typename T, typename T2, typename P>
        inline bool operator==(STLAllocator<T,P> const&,
                STLAllocator<T2,P> const&)
        {
                // same alloc policy (P), memory can be freed
                return true;
        }

        /// determine equality, can memory from another allocator
        /// be released by this allocator, (ISO C++)
        template<typename T, typename P, typename OtherAllocator>
        inline bool operator==(STLAllocator<T,P> const&,
                OtherAllocator const&)
        {
                return false;
        }
        /// determine equality, can memory from another allocator
        /// be released by this allocator, (ISO C++)
        template<typename T, typename T2, typename P>
        inline bool operator!=(STLAllocator<T,P> const&,
                STLAllocator<T2,P> const&)
        {
                // same alloc policy (P), memory can be freed
                return false;
        }

        /// determine equality, can memory from another allocator
        /// be released by this allocator, (ISO C++)
        template<typename T, typename P, typename OtherAllocator>
        inline bool operator!=(STLAllocator<T,P> const&,
                OtherAllocator const&)
        {
                return true;
        }


        /** @} */
        /** @} */

}// namespace Ogre


#include "OgreHeaderSuffix.h"

#endif // _MemorySTLAllocator_H__