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   1 //////////////////////////////////////////////////////////////////////////////
   2 // (c) Copyright Andreas Huber Doenni 2002-2005, Eric Niebler 2006
   3 // Distributed under the Boost Software License, Version 1.0. (See accompany-
   4 // ing file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   5 //////////////////////////////////////////////////////////////////////////////
   6
   7 #ifndef BOOST_XPRESSIVE_DETAIL_UTILITY_COUNTED_BASE_HPP_EAN_04_16_2006
   8 #define BOOST_XPRESSIVE_DETAIL_UTILITY_COUNTED_BASE_HPP_EAN_04_16_2006
   9
  10 #include <boost/assert.hpp>
  11 #include <boost/checked_delete.hpp>
  12 #include <boost/detail/atomic_count.hpp>
  13
  14 namespace boost { namespace xpressive { namespace detail
  15 {
  16     template<typename Derived>
  17     struct counted_base_access;
  18
  19     //////////////////////////////////////////////////////////////////////////////
  20     // counted_base
  21     template<typename Derived>
  22     struct counted_base
  23     {
  24         long use_count() const
  25         {
  26             return this->count_;
  27         }
  28
  29     protected:
  30         counted_base()
  31           : count_(0)
  32         {
  33         }
  34
  35         counted_base(counted_base<Derived> const &)
  36           : count_(0)
  37         {
  38         }
  39
  40         counted_base &operator =(counted_base<Derived> const &)
  41         {
  42             return *this;
  43         }
  44
  45     private:
  46         friend struct counted_base_access<Derived>;
  47         mutable boost::detail::atomic_count count_;
  48     };
  49
  50     //////////////////////////////////////////////////////////////////////////////
  51     // counted_base_access
  52     template<typename Derived>
  53     struct counted_base_access
  54     {
  55         static void add_ref(counted_base<Derived> const *that)
  56         {
  57             ++that->count_;
  58         }
  59
  60         static void release(counted_base<Derived> const *that)
  61         {
  62             BOOST_ASSERT(0 < that->count_);
  63             if(0 == --that->count_)
  64             {
  65                 boost::checked_delete(static_cast<Derived const *>(that));
  66             }
  67         }
  68     };
  69
  70     template<typename Derived>
  71     inline void intrusive_ptr_add_ref(counted_base<Derived> const *that)
  72     {
  73         counted_base_access<Derived>::add_ref(that);
  74     }
  75
  76     template<typename Derived>
  77     inline void intrusive_ptr_release(counted_base<Derived> const *that)
  78     {
  79         counted_base_access<Derived>::release(that);
  80     }
  81
  82 }}} // namespace boost::xpressive::detail
  83
  84 #endif