boost/spirit/home/support/iterators/detail/first_owner_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_FIRST_OWNER_POLICY_MAR_16_2007_1108AM)
#define BOOST_SPIRIT_ITERATOR_FIRST_OWNER_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>
namespace boost { namespace spirit { namespace iterator_policies
{
///////////////////////////////////////////////////////////////////////////
// class first_owner
// Implementation of an OwnershipPolicy used by multi_pass
// This ownership policy dictates that the first iterator created will
// determine the lifespan of the shared components. This works well for
// spirit, since no dynamic allocation of iterators is done, and all
// copies are make on the stack.
//
// There is a caveat about using this policy together with the std_deque
// StoragePolicy. Since first_owner always returns false from unique(),
// std_deque will only release the queued data if clear_queue() is called.
///////////////////////////////////////////////////////////////////////////
struct first_owner
{
///////////////////////////////////////////////////////////////////////
struct unique : detail::default_ownership_policy
{
unique() : first(true) {}
unique(unique const&) : first(false) {}
// return true to indicate deletion of resources
template <typename MultiPass>
static bool release(MultiPass& mp)
{
return mp.first;
}
// use swap from default policy
// if we're the first, we still remain the first, even if assigned
// to, so don't swap first. swap is only called from operator=
template <typename MultiPass>
static bool is_unique(MultiPass const&)
{
return false; // no way to know, so always return false
}
protected:
bool first;
};
////////////////////////////////////////////////////////////////////////
struct shared {}; // no shared data
};
}}}
#endif