boost/spirit/home/support/iterators/detail/ref_counted_policy.hpp
// Copyright (c) 2001 Daniel C. Nuffer
// Copyright (c) 2001-2011 Hartmut Kaiser
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
#if !defined(BOOST_SPIRIT_ITERATOR_REF_COUNTED_POLICY_MAR_16_2007_1108AM)
#define BOOST_SPIRIT_ITERATOR_REF_COUNTED_POLICY_MAR_16_2007_1108AM
#include <boost/spirit/home/support/iterators/multi_pass_fwd.hpp>
#include <boost/spirit/home/support/iterators/detail/multi_pass.hpp>
#if defined(BOOST_HAS_THREADS)
#include <boost/detail/atomic_count.hpp>
#endif
#include <cstdlib>
namespace boost { namespace spirit { namespace iterator_policies
{
///////////////////////////////////////////////////////////////////////////
// class ref_counted
// Implementation of an OwnershipPolicy used by multi_pass.
//
// Implementation modified from RefCounted class from the Loki library by
// Andrei Alexandrescu.
///////////////////////////////////////////////////////////////////////////
struct ref_counted
{
///////////////////////////////////////////////////////////////////////
struct unique // : detail::default_ownership_policy
{
void swap(unique&) {}
// clone is called when a copy of the iterator is made, so
// increment the ref-count.
template <typename MultiPass>
static void clone(MultiPass& mp)
{
if (0 != mp.shared())
++mp.shared()->count;
}
// called when a copy is deleted. Decrement the ref-count. Return
// value of true indicates that the last copy has been released.
template <typename MultiPass>
static bool release(MultiPass& mp)
{
return 0 != mp.shared() && 0 == --mp.shared()->count;
}
// returns true if there is only one iterator in existence.
// std_deque StoragePolicy will free it's buffered data if this
// returns true.
template <typename MultiPass>
static bool is_unique(MultiPass const& mp)
{
return 0 == mp.shared() || 1 == mp.shared()->count;
}
template <typename MultiPass>
static void destroy(MultiPass&) {}
};
////////////////////////////////////////////////////////////////////////
struct shared
{
shared() : count(1) {}
#if defined(BOOST_HAS_THREADS)
boost::detail::atomic_count count;
#else
std::size_t count;
#endif
};
};
}}}
#endif