stack_allocator.h   [plain text]

#ifndef STACK_ALLOCATOR_H
#define STACK_ALLOCATOR_H

#include <cstddef>
#include <new>

template <class T, std::size_t N>
class stack_allocator
{
    char buf_[sizeof(T)*N];
    char* ptr_;
public:
    typedef T                 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;

    template <class U> struct rebind {typedef stack_allocator<U, N> other;};

    stack_allocator() : ptr_(buf_) {}

private:
    stack_allocator(const stack_allocator&);// = delete;
    stack_allocator& operator=(const stack_allocator&);// = delete;

public:
    pointer allocate(size_type n, const void* = 0)
    {
        if (n > N - (ptr_ - buf_) / sizeof(value_type))
            throw std::bad_alloc();
        pointer r = (T*)ptr_;
        ptr_ += n * sizeof(T);
        return r;
    }
    void deallocate(pointer p, size_type n)
    {
        if ((char*)(p + n) == ptr_)
            ptr_ = (char*)p;
    }

    size_type max_size() const {return N;}
};

template <class T, std::size_t N>
inline
void
swap(stack_allocator<T, N>& x, stack_allocator<T, N>& y) {}

#endif  // STACK_ALLOCATOR_H