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   1 //  Copyright (c) 2001 Daniel C. Nuffer
   2 //  Copyright (c) 2001-2011 Hartmut Kaiser
   3 //
   4 //  Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #if !defined(BOOST_SPIRIT_ITERATOR_REF_COUNTED_POLICY_MAR_16_2007_1108AM)
   8 #define BOOST_SPIRIT_ITERATOR_REF_COUNTED_POLICY_MAR_16_2007_1108AM
   9
  10 #include <boost/spirit/home/support/iterators/multi_pass_fwd.hpp>
  11 #include <boost/spirit/home/support/iterators/detail/multi_pass.hpp>
  12 #if defined(BOOST_HAS_THREADS)
  13 #include <boost/detail/atomic_count.hpp>
  14 #endif
  15 #include <cstdlib>
  16
  17 namespace boost { namespace spirit { namespace iterator_policies
  18 {
  19     ///////////////////////////////////////////////////////////////////////////
  20     //  class ref_counted
  21     //  Implementation of an OwnershipPolicy used by multi_pass.
  22     //
  23     //  Implementation modified from RefCounted class from the Loki library by
  24     //  Andrei Alexandrescu.
  25     ///////////////////////////////////////////////////////////////////////////
  26     struct ref_counted
  27     {
  28         ///////////////////////////////////////////////////////////////////////
  29         struct unique // : detail::default_ownership_policy
  30         {
  31             void swap(unique&) {}
  32
  33             // clone is called when a copy of the iterator is made, so
  34             // increment the ref-count.
  35             template <typename MultiPass>
  36             static void clone(MultiPass& mp)
  37             {
  38                 if (0 != mp.shared())
  39                     ++mp.shared()->count;
  40             }
  41
  42             // called when a copy is deleted. Decrement the ref-count. Return
  43             // value of true indicates that the last copy has been released.
  44             template <typename MultiPass>
  45             static bool release(MultiPass& mp)
  46             {
  47                 return 0 != mp.shared() && 0 == --mp.shared()->count;
  48             }
  49
  50             // returns true if there is only one iterator in existence.
  51             // std_deque StoragePolicy will free it's buffered data if this
  52             // returns true.
  53             template <typename MultiPass>
  54             static bool is_unique(MultiPass const& mp)
  55             {
  56                 return 0 == mp.shared() || 1 == mp.shared()->count;
  57             }
  58
  59             template <typename MultiPass>
  60             static void destroy(MultiPass&) {}
  61         };
  62
  63         ////////////////////////////////////////////////////////////////////////
  64         struct shared
  65         {
  66             shared() : count(1) {}
  67
  68 #if defined(BOOST_HAS_THREADS)
  69             boost::detail::atomic_count count;
  70 #else
  71             std::size_t count;
  72 #endif
  73         };
  74
  75     };
  76
  77 }}}
  78
  79 #endif