detail/utility/counted_base.hpp

0001 //////////////////////////////////////////////////////////////////////////////
0002 // (c) Copyright Andreas Huber Doenni 2002-2005, Eric Niebler 2006
0003 // Distributed under the Boost Software License, Version 1.0. (See accompany-
0004 // ing file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0005 //////////////////////////////////////////////////////////////////////////////
0006
0007 #ifndef BOOST_XPRESSIVE_DETAIL_UTILITY_COUNTED_BASE_HPP_EAN_04_16_2006
0008 #define BOOST_XPRESSIVE_DETAIL_UTILITY_COUNTED_BASE_HPP_EAN_04_16_2006
0009
0010 #include <boost/assert.hpp>
0011 #include <boost/checked_delete.hpp>
0012 #include <boost/detail/atomic_count.hpp>
0013
0014 namespace boost { namespace xpressive { namespace detail
0015 {
0016     template<typename Derived>
0017     struct counted_base_access;
0018
0019     //////////////////////////////////////////////////////////////////////////////
0020     // counted_base
0021     template<typename Derived>
0022     struct counted_base
0023     {
0024         long use_count() const
0025         {
0026             return this->count_;
0027         }
0028
0029     protected:
0030         counted_base()
0031           : count_(0)
0032         {
0033         }
0034
0035         counted_base(counted_base<Derived> const &)
0036           : count_(0)
0037         {
0038         }
0039
0040         counted_base &operator =(counted_base<Derived> const &)
0041         {
0042             return *this;
0043         }
0044
0045     private:
0046         friend struct counted_base_access<Derived>;
0047         mutable boost::detail::atomic_count count_;
0048     };
0049
0050     //////////////////////////////////////////////////////////////////////////////
0051     // counted_base_access
0052     template<typename Derived>
0053     struct counted_base_access
0054     {
0055         static void add_ref(counted_base<Derived> const *that)
0056         {
0057             ++that->count_;
0058         }
0059
0060         static void release(counted_base<Derived> const *that)
0061         {
0062             BOOST_ASSERT(0 < that->count_);
0063             if(0 == --that->count_)
0064             {
0065                 boost::checked_delete(static_cast<Derived const *>(that));
0066             }
0067         }
0068     };
0069
0070     template<typename Derived>
0071     inline void intrusive_ptr_add_ref(counted_base<Derived> const *that)
0072     {
0073         counted_base_access<Derived>::add_ref(that);
0074     }
0075
0076     template<typename Derived>
0077     inline void intrusive_ptr_release(counted_base<Derived> const *that)
0078     {
0079         counted_base_access<Derived>::release(that);
0080     }
0081
0082 }}} // namespace boost::xpressive::detail
0083
0084 #endif