allocators.hpp

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#ifndef _UTILS_ALLOCATORS_HPP_INCLUDED
#define _UTILS_ALLOCATORS_HPP_INCLUDED
#include <cstddef>
#include <stdexcept>
#include <new>

namespace _Wolframe {
namespace utils {

class GreedySmallChunkAllocator
{
public:
        GreedySmallChunkAllocator();
        ~GreedySmallChunkAllocator();
        void* alloc( std::size_t nofBytes);

private:
        class MemChunk;
        MemChunk* m_chunk;
};


class ArrayDoublingAllocator
{
public:
        ArrayDoublingAllocator();
        ~ArrayDoublingAllocator();

        std::size_t alloc( std::size_t nofBytes);
        const void* base() const                        {return m_ar;}
        void* base()                                    {return m_ar;}
        std::size_t size() const                        {return m_pos;}

private:
        enum {InitBlockSize=(1<<14)};
        char* m_ar;
        std::size_t m_size;
        std::size_t m_pos;
};


template <typename Type>
struct TypedArrayDoublingAllocator :public ArrayDoublingAllocator
{
        const Type* base() const
        {
                return (const Type*)ArrayDoublingAllocator::base();
        }

        Type* base()
        {
                return (Type*)ArrayDoublingAllocator::base();
        }

        const Type& operator[]( std::size_t idx) const
        {
                if (idx > size()/sizeof(Type))
                {
                        throw std::logic_error( "Array bounds access");
                }
                return ((const Type*)ArrayDoublingAllocator::base())[ idx];
        }

        Type& operator[]( std::size_t idx)
        {
                if (idx > size()/sizeof(Type))
                {
                        throw std::logic_error( "Array bounds access");
                }
                return ((Type*)ArrayDoublingAllocator::base())[ idx];
        }

        std::size_t alloc( unsigned int nof)
        {
                std::size_t mm = nof * sizeof(Type);
                if (mm < nof) throw std::bad_alloc();
                std::size_t idx = ArrayDoublingAllocator::alloc( mm);
                return idx / sizeof(Type);
        }
};

}}//namespace
#endif