stl_alloc.h

俄罗斯高人Mamaich的Pocket gcc编译器（运行在PocketPC上）的全部源代码。

      allocator() throw() {}
      allocator(const allocator&) throw() {}
      template<typename _Tp1>
        allocator(const allocator<_Tp1>&) throw() {}
      ~allocator() throw() {}

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

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

      // NB: __n is permitted to be 0.  The C++ standard says nothing
      // about what the return value is when __n == 0.
      _Tp*
      allocate(size_type __n, const void* = 0)
      {
	_Tp* __ret = 0;
	if (__n)
	  {
	    if (__n <= this->max_size())
	      __ret = static_cast<_Tp*>(_Alloc::allocate(__n * sizeof(_Tp)));
	    else
	      __throw_bad_alloc();
	  }
	return __ret;
      }

      // __p is not permitted to be a null pointer.
      void
      deallocate(pointer __p, size_type __n)
      { _Alloc::deallocate(__p, __n * sizeof(_Tp)); }

      size_type
      max_size() const throw() { return size_t(-1) / sizeof(_Tp); }

      void construct(pointer __p, const _Tp& __val) { new(__p) _Tp(__val); }
      void destroy(pointer __p) { __p->~_Tp(); }
    };

  template<>
    class allocator<void>
    {
    public:
      typedef size_t      size_type;
      typedef ptrdiff_t   difference_type;
      typedef void*       pointer;
      typedef const void* const_pointer;
      typedef void        value_type;

      template<typename _Tp1>
        struct rebind
        { typedef allocator<_Tp1> other; };
    };


  template<typename _T1, typename _T2>
    inline bool
    operator==(const allocator<_T1>&, const allocator<_T2>&)
    { return true; }

  template<typename _T1, typename _T2>
    inline bool
    operator!=(const allocator<_T1>&, const allocator<_T2>&)
    { return false; }


  /**
   *  @if maint
   *  Allocator adaptor to turn an "SGI" style allocator (e.g.,
   *  __alloc, __malloc_alloc_template) into a "standard" conforming
   *  allocator.  Note that this adaptor does *not* assume that all
   *  objects of the underlying alloc class are identical, nor does it
   *  assume that all of the underlying alloc's member functions are
   *  static member functions.  Note, also, that __allocator<_Tp,
   *  __alloc> is essentially the same thing as allocator<_Tp>.
   *  @endif
   *  (See @link Allocators allocators info @endlink for more.)
   */
  template<typename _Tp, typename _Alloc>
    struct __allocator
    {
      _Alloc __underlying_alloc;
      
      typedef size_t    size_type;
      typedef ptrdiff_t difference_type;
      typedef _Tp*       pointer;
      typedef const _Tp* const_pointer;
      typedef _Tp&       reference;
      typedef const _Tp& const_reference;
      typedef _Tp        value_type;

      template<typename _Tp1>
        struct rebind
        { typedef __allocator<_Tp1, _Alloc> other; };

      __allocator() throw() {}
      __allocator(const __allocator& __a) throw()
      : __underlying_alloc(__a.__underlying_alloc) {}

      template<typename _Tp1>
        __allocator(const __allocator<_Tp1, _Alloc>& __a) throw()
        : __underlying_alloc(__a.__underlying_alloc) {}

      ~__allocator() throw() {}

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

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

      // NB: __n is permitted to be 0.  The C++ standard says nothing
      // about what the return value is when __n == 0.
      _Tp*
      allocate(size_type __n, const void* = 0)
      {
	_Tp* __ret = 0;
	if (__n)
	  __ret = static_cast<_Tp*>(_Alloc::allocate(__n * sizeof(_Tp)));
	return __ret;
      }

      // __p is not permitted to be a null pointer.
      void
      deallocate(pointer __p, size_type __n)
      { __underlying_alloc.deallocate(__p, __n * sizeof(_Tp)); }
      
      size_type
      max_size() const throw() { return size_t(-1) / sizeof(_Tp); }
      
      void
      construct(pointer __p, const _Tp& __val) { new(__p) _Tp(__val); }
      
      void
      destroy(pointer __p) { __p->~_Tp(); }
    };

  template<typename _Alloc>
    struct __allocator<void, _Alloc>
    {
      typedef size_t      size_type;
      typedef ptrdiff_t   difference_type;
      typedef void*       pointer;
      typedef const void* const_pointer;
      typedef void        value_type;

      template<typename _Tp1>
        struct rebind
        { typedef __allocator<_Tp1, _Alloc> other; };
    };

  template<typename _Tp, typename _Alloc>
    inline bool
    operator==(const __allocator<_Tp,_Alloc>& __a1,
               const __allocator<_Tp,_Alloc>& __a2)
    { return __a1.__underlying_alloc == __a2.__underlying_alloc; }

  template<typename _Tp, typename _Alloc>
    inline bool
    operator!=(const __allocator<_Tp, _Alloc>& __a1,
               const __allocator<_Tp, _Alloc>& __a2)
    { return __a1.__underlying_alloc != __a2.__underlying_alloc; }


  //@{
  /** Comparison operators for all of the predifined SGI-style allocators.
   *  This ensures that __allocator<malloc_alloc> (for example) will work
   *  correctly.  As required, all allocators compare equal.
   */
  template<int inst>
    inline bool
    operator==(const __malloc_alloc_template<inst>&,
               const __malloc_alloc_template<inst>&)
    { return true; }

  template<int __inst>
    inline bool
    operator!=(const __malloc_alloc_template<__inst>&,
               const __malloc_alloc_template<__inst>&)
    { return false; }

  template<typename _Alloc>
    inline bool
    operator==(const __debug_alloc<_Alloc>&, const __debug_alloc<_Alloc>&)
    { return true; }

  template<typename _Alloc>
    inline bool
    operator!=(const __debug_alloc<_Alloc>&, const __debug_alloc<_Alloc>&)
    { return false; }
  //@}


  /**
   *  @if maint
   *  Another allocator adaptor:  _Alloc_traits.  This serves two purposes.
   *  First, make it possible to write containers that can use either "SGI"
   *  style allocators or "standard" allocators.  Second, provide a mechanism
   *  so that containers can query whether or not the allocator has distinct
   *  instances.  If not, the container can avoid wasting a word of memory to
   *  store an empty object.  For examples of use, see stl_vector.h, etc, or
   *  any of the other classes derived from this one.
   *
   *  This adaptor uses partial specialization.  The general case of
   *  _Alloc_traits<_Tp, _Alloc> assumes that _Alloc is a
   *  standard-conforming allocator, possibly with non-equal instances and
   *  non-static members.  (It still behaves correctly even if _Alloc has
   *  static member and if all instances are equal.  Refinements affect
   *  performance, not correctness.)
   *
   *  There are always two members:  allocator_type, which is a standard-
   *  conforming allocator type for allocating objects of type _Tp, and
   *  _S_instanceless, a static const member of type bool.  If
   *  _S_instanceless is true, this means that there is no difference
   *  between any two instances of type allocator_type.  Furthermore, if
   *  _S_instanceless is true, then _Alloc_traits has one additional
   *  member:  _Alloc_type.  This type encapsulates allocation and
   *  deallocation of objects of type _Tp through a static interface; it
   *  has two member functions, whose signatures are
   *
   *  -  static _Tp* allocate(size_t)
   *  -  static void deallocate(_Tp*, size_t)
   *
   *  The size_t parameters are "standard" style (see top of stl_alloc.h) in
   *  that they take counts, not sizes.
   *
   *  @endif
   *  (See @link Allocators allocators info @endlink for more.)
   */
  //@{
  // The fully general version.
  template<typename _Tp, typename _Allocator>
    struct _Alloc_traits
    {
      static const bool _S_instanceless = false;
      typedef typename _Allocator::template rebind<_Tp>::other allocator_type;
    };

  template<typename _Tp, typename _Allocator>
    const bool _Alloc_traits<_Tp, _Allocator>::_S_instanceless;

  /// The version for the default allocator.
  template<typename _Tp, typename _Tp1>
    struct _Alloc_traits<_Tp, allocator<_Tp1> >
    {
      static const bool _S_instanceless = true;
      typedef __simple_alloc<_Tp, __alloc> _Alloc_type;
      typedef allocator<_Tp> allocator_type;
    };
  //@}

  //@{
  /// Versions for the predefined "SGI" style allocators.
  template<typename _Tp, int __inst>
    struct _Alloc_traits<_Tp, __malloc_alloc_template<__inst> >
    {
      static const bool _S_instanceless = true;
      typedef __simple_alloc<_Tp, __malloc_alloc_template<__inst> > _Alloc_type;
      typedef __allocator<_Tp, __malloc_alloc_template<__inst> > allocator_type;
    };

  template<typename _Tp, bool __threads, int __inst>
    struct _Alloc_traits<_Tp, __default_alloc_template<__threads, __inst> >
    {
      static const bool _S_instanceless = true;
      typedef __simple_alloc<_Tp, __default_alloc_template<__threads, __inst> >
      _Alloc_type;
      typedef __allocator<_Tp, __default_alloc_template<__threads, __inst> >
      allocator_type;
    };

  template<typename _Tp, typename _Alloc>
    struct _Alloc_traits<_Tp, __debug_alloc<_Alloc> >
    {
      static const bool _S_instanceless = true;
      typedef __simple_alloc<_Tp, __debug_alloc<_Alloc> > _Alloc_type;
      typedef __allocator<_Tp, __debug_alloc<_Alloc> > allocator_type;
    };
  //@}

  //@{
  /// Versions for the __allocator adaptor used with the predefined
  /// "SGI" style allocators.
  template<typename _Tp, typename _Tp1, int __inst>
    struct _Alloc_traits<_Tp,
                         __allocator<_Tp1, __malloc_alloc_template<__inst> > >
    {
      static const bool _S_instanceless = true;
      typedef __simple_alloc<_Tp, __malloc_alloc_template<__inst> > _Alloc_type;
      typedef __allocator<_Tp, __malloc_alloc_template<__inst> > allocator_type;
    };

  template<typename _Tp, typename _Tp1, bool __thr, int __inst>
    struct _Alloc_traits<_Tp, __allocator<_Tp1, __default_alloc_template<__thr, __inst> > >
    {
      static const bool _S_instanceless = true;
      typedef __simple_alloc<_Tp, __default_alloc_template<__thr,__inst> >
      _Alloc_type;
      typedef __allocator<_Tp, __default_alloc_template<__thr,__inst> >
      allocator_type;
    };

  template<typename _Tp, typename _Tp1, typename _Alloc>
    struct _Alloc_traits<_Tp, __allocator<_Tp1, __debug_alloc<_Alloc> > >
    {
      static const bool _S_instanceless = true;
      typedef __simple_alloc<_Tp, __debug_alloc<_Alloc> > _Alloc_type;
      typedef __allocator<_Tp, __debug_alloc<_Alloc> > allocator_type;
    };
  //@}

  // Inhibit implicit instantiations for required instantiations,
  // which are defined via explicit instantiations elsewhere.
  // NB: This syntax is a GNU extension.
#if _GLIBCPP_EXTERN_TEMPLATE
  extern template class allocator<char>;
  extern template class allocator<wchar_t>;
  extern template class __default_alloc_template<true,0>;
#endif
} // namespace std

#endif