utilities.hpp

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      :  const_void_ptr_(ptr)
   {}

   const void *get_ptr() const
   {  return detail::get_pointer(const_void_ptr_);  }

   ConstVoidPtr const_void_ptr_;
};

template <class VoidPointer, bool store_ptr>
struct select_constptr
{
   typedef typename detail::if_c
      < store_ptr
      , constptr<VoidPointer>
      , dummy_constptr
      >::type type;
};

template <class Container>
struct store_cont_ptr_on_it
{
   typedef typename Container::value_traits value_traits;
   static const bool value = 
      !detail::is_empty_class<value_traits>::value
   || detail::external_value_traits_is_true<value_traits>::value
   ;
};

template<class T, bool Add>
struct add_const_if_c
{
   typedef typename detail::if_c
      < Add
      , typename detail::add_const<T>::type
      , T
      >::type type;
};

template<class Container, bool IsConst>
struct node_to_value
   :  public detail::select_constptr
      < typename boost::pointer_to_other
            <typename Container::pointer, void>::type
      , detail::store_cont_ptr_on_it<Container>::value
      >::type
{
   static const bool store_container_ptr = 
      detail::store_cont_ptr_on_it<Container>::value;

   typedef typename Container::real_value_traits         real_value_traits;
   typedef typename real_value_traits::value_type        value_type;
   typedef typename detail::select_constptr
      < typename boost::pointer_to_other
         <typename Container::pointer, void>::type
      , store_container_ptr >::type                      Base;
   typedef typename real_value_traits::node_traits::node node;
   typedef typename detail::add_const_if_c
         <value_type, IsConst>::type                  vtype;
   typedef typename detail::add_const_if_c
         <node, IsConst>::type                        ntype;
   typedef typename boost::pointer_to_other
      <typename Container::pointer, ntype>::type      npointer;

   node_to_value(const Container *cont)
      :  Base(cont)
   {}

   typedef vtype &                                 result_type;
   typedef ntype &                                 first_argument_type;

   const Container *get_container() const
   {
      if(store_container_ptr)
         return static_cast<const Container*>(Base::get_ptr());
      else
         return 0;
   }

   const real_value_traits *get_real_value_traits() const
   {
      if(store_container_ptr)
         return &this->get_container()->get_real_value_traits();
      else
         return 0;
   }

   result_type operator()(first_argument_type arg) const
   {  return *(this->get_real_value_traits()->to_value_ptr(npointer(&arg))); }
};

template <link_mode_type LinkMode>
struct link_dispatch
{};

template<class Hook>
void destructor_impl(Hook &hook, detail::link_dispatch<safe_link>)
{  //If this assertion raises, you might have destroyed an object
   //while it was still inserted in a container that is alive.
   //If so, remove the object from the container before destroying it.
   (void)hook; BOOST_INTRUSIVE_SAFE_HOOK_DESTRUCTOR_ASSERT(!hook.is_linked());
}

template<class Hook>
void destructor_impl(Hook &hook, detail::link_dispatch<auto_unlink>)
{  hook.unlink();  }

template<class Hook>
void destructor_impl(Hook &, detail::link_dispatch<normal_link>)
{}

template<class T, class NodeTraits, link_mode_type LinkMode, class Tag, int HookType>
struct base_hook_traits
{
   public:
   typedef detail::node_holder
      <typename NodeTraits::node, Tag, LinkMode, HookType>           node_holder;
   typedef NodeTraits                                                node_traits;
   typedef T                                                         value_type;
   typedef typename node_traits::node_ptr                            node_ptr;
   typedef typename node_traits::const_node_ptr                      const_node_ptr;
   typedef typename boost::pointer_to_other<node_ptr, T>::type       pointer;
   typedef typename boost::pointer_to_other<node_ptr, const T>::type const_pointer;
   typedef typename std::iterator_traits<pointer>::reference         reference;
   typedef typename std::iterator_traits<const_pointer>::reference   const_reference;
   static const link_mode_type link_mode = LinkMode;

   static node_ptr to_node_ptr(reference value)
   { return static_cast<node_holder*>(&value); }

   static const_node_ptr to_node_ptr(const_reference value)
   {  return static_cast<const node_holder*>(&value);  }

   static pointer to_value_ptr(node_ptr n) 
   {  return static_cast<T*>(static_cast<node_holder*>(&*n));   }

   static const_pointer to_value_ptr(const_node_ptr n)
   {  return static_cast<const T*>(static_cast<const node_holder*>(&*n));   }
};

template<class T, class Hook, Hook T::* P>
struct member_hook_traits
{
   public:
   typedef Hook                                                      hook_type;
   typedef typename hook_type::boost_intrusive_tags::node_traits     node_traits;
   typedef typename node_traits::node                                node;
   typedef T                                                         value_type;
   typedef typename node_traits::node_ptr                            node_ptr;
   typedef typename node_traits::const_node_ptr                      const_node_ptr;
   typedef typename boost::pointer_to_other<node_ptr, T>::type       pointer;
   typedef typename boost::pointer_to_other<node_ptr, const T>::type const_pointer;
   typedef typename std::iterator_traits<pointer>::reference         reference;
   typedef typename std::iterator_traits<const_pointer>::reference   const_reference;
   static const link_mode_type link_mode = Hook::boost_intrusive_tags::link_mode;

   static node_ptr to_node_ptr(reference value)
   {
      return reinterpret_cast<node*>(&(value.*P));
   }

   static const_node_ptr to_node_ptr(const_reference value)
   {
      return static_cast<const node*>(&(value.*P));
   }

   static pointer to_value_ptr(node_ptr n)
   {
      return detail::parent_from_member<T, Hook>
         (static_cast<Hook*>(detail::get_pointer(n)), P);
   }

   static const_pointer to_value_ptr(const_node_ptr n)
   {
      return detail::parent_from_member<T, Hook>
         (static_cast<const Hook*>(detail::get_pointer(n)), P);
   }
};

//This function uses binary search to discover the
//highest set bit of the integer
inline std::size_t floor_log2 (std::size_t x)
{
   const std::size_t Bits = sizeof(std::size_t)*CHAR_BIT;
   const bool Size_t_Bits_Power_2= !(Bits & (Bits-1));
   BOOST_STATIC_ASSERT(Size_t_Bits_Power_2);

   std::size_t n = x;
   std::size_t log2 = 0;
   
   for(std::size_t shift = Bits >> 1; shift; shift >>= 1){
      std::size_t tmp = n >> shift;
      if (tmp)
         log2 += shift, n = tmp;
   }

   return log2;
}

inline float fast_log2 (float val)
{
   boost::uint32_t * exp_ptr =
      static_cast<boost::uint32_t *>(static_cast<void*>(&val));
   boost::uint32_t x = *exp_ptr;
   const int log_2 = (int)(((x >> 23) & 255) - 128);
   x &= ~(255 << 23);
   x += 127 << 23;
   *exp_ptr = x;

   val = ((-1.0f/3) * val + 2) * val - 2.0f/3;

   return (val + log_2);
}

inline std::size_t ceil_log2 (std::size_t x)
{
   return ((x & (x-1))!= 0) + floor_log2(x);
}

template<class SizeType, std::size_t N>
struct numbits_eq
{
   static const bool value = sizeof(SizeType)*CHAR_BIT == N;
};

template<class SizeType, class Enabler = void >
struct sqrt2_pow_max;

template <class SizeType>
struct sqrt2_pow_max<SizeType, typename enable_if< numbits_eq<SizeType, 32> >::type>
{
   static const boost::uint32_t value = 0xb504f334;
   static const std::size_t pow   = 31;
};

template <class SizeType>
struct sqrt2_pow_max<SizeType, typename enable_if< numbits_eq<SizeType, 64> >::type>
{
   static const boost::uint64_t value = 0xb504f333f9de6484ull;
   static const std::size_t pow   = 63;
};

// Returns floor(pow(sqrt(2), x * 2 + 1)).
// Defined for X from 0 up to the number of bits in size_t minus 1.
inline std::size_t sqrt2_pow_2xplus1 (std::size_t x)
{
   const std::size_t value = (std::size_t)sqrt2_pow_max<std::size_t>::value;
   const std::size_t pow   = (std::size_t)sqrt2_pow_max<std::size_t>::pow;
   return (value >> (pow - x)) + 1;
}

template<class Container, class Disposer>
class exception_disposer
{
   Container *cont_;
   Disposer  &disp_;

   exception_disposer(const exception_disposer&);
   exception_disposer &operator=(const exception_disposer&);

   public:
   exception_disposer(Container &cont, Disposer &disp)
      :  cont_(&cont), disp_(disp)
   {}

   void release()
   {  cont_ = 0;  }

   ~exception_disposer()
   {
      if(cont_){
         cont_->clear_and_dispose(disp_);
      }
   }
};

template<class Container, class Disposer>
class exception_array_disposer
{
   Container *cont_;
   Disposer  &disp_;
   typename Container::size_type  &constructed_;

   exception_array_disposer(const exception_array_disposer&);
   exception_array_disposer &operator=(const exception_array_disposer&);

   public:
   typedef typename Container::size_type size_type;
   exception_array_disposer
      (Container &cont, Disposer &disp, size_type &constructed)
      :  cont_(&cont), disp_(disp), constructed_(constructed)
   {}

   void release()
   {  cont_ = 0;  }

   ~exception_array_disposer()
   {
      size_type n = constructed_;
      if(cont_){
         while(n--){
            cont_[n].clear_and_dispose(disp_);
         }
      }
   }
};

} //namespace detail
} //namespace intrusive 
} //namespace boost 

#include <boost/intrusive/detail/config_end.hpp>

#endif //BOOST_INTRUSIVE_DETAIL_UTILITIES_HPP