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
17namespace 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
80