debugging_allocator.h

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#ifndef art_Persistency_Common_debugging_allocator_h
#define art_Persistency_Common_debugging_allocator_h

//---------------------------------------------------------------------
//
// This file declares and defines an allocator class template.
// This allocator is intended for use with the memory checking tool
// valgrind. It is a minimum conformant implementation which makes sure
// not use use any unitialized memory, and so it causes no spurious error
// reports from valgrind.
//
// The intended use is in the declarations of objects from STL templates,
// e.g.
//    typedef vector<int, art::debugging_allocator<int> > vint;
// etc.
//
//
//---------------------------------------------------------------------

#include <cstddef>
#include <limits>

namespace art {
  template <class T>
  class debugging_allocator {
  public:
    typedef std::size_t size_type;
    typedef ptrdiff_t difference_type;
    typedef T* pointer;
    typedef T const* const_pointer;
    typedef T& reference;
    typedef T const& const_reference;
    typedef T value_type;

    template <class U>
    struct rebind {
      typedef debugging_allocator<U> other;
    };

    debugging_allocator() throw() : dummy('x') {}

    debugging_allocator(debugging_allocator const&) throw() : dummy('c') {}

    template <class U>
    debugging_allocator(debugging_allocator<U> const&) throw() : dummy('u')
    {}

    ~debugging_allocator() throw(){};

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

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

    size_type
    max_size() const throw()
    {
      return std::numeric_limits<size_type>::max() / sizeof(T);
    }

    pointer
    allocate(size_type num, void const* hint = 0)
    {
      // allocate objects with global new
      return (pointer)(::operator new(num * sizeof(T)));
    }

    void
    construct(pointer p, T const& value)
    {
      new ((void*)p) T(value);
    }

    void
    destroy(pointer p)
    {
      p->~T();
    }

    void
    deallocate(pointer p, size_type num)
    {
      ::operator delete((void*)p);
    }

  private:
    char dummy;
  };

  // instances of all specializations of this allocator are equal
  template <class X, class Y>
  bool
  operator==(debugging_allocator<X> const&,
             debugging_allocator<Y> const&) throw()
  {
    return true;
  }

  template <class X, class Y>
  bool
  operator!=(debugging_allocator<X> const&,
             debugging_allocator<Y> const&) throw()
  {
    return false;
  }

} // namespace art

#endif /* art_Persistency_Common_debugging_allocator_h */

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