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- // 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_FIXED_SIZE_QUEUE_POLICY_MAR_16_2007_1134AM)
- #define BOOST_SPIRIT_ITERATOR_FIXED_SIZE_QUEUE_POLICY_MAR_16_2007_1134AM
- #include <boost/spirit/home/support/iterators/detail/multi_pass.hpp>
- #include <boost/spirit/home/support/iterators/detail/fixed_size_queue.hpp>
- #include <boost/assert.hpp>
- #include <cstdlib>
- namespace boost { namespace spirit { namespace iterator_policies
- {
- ///////////////////////////////////////////////////////////////////////////
- // class fixed_size_queue
- // Implementation of the StoragePolicy used by multi_pass
- // fixed_size_queue keeps a circular buffer (implemented by
- // boost::spirit::fixed_size_queue class) that is size N+1 and stores N
- // elements.
- //
- // It is up to the user to ensure that there is enough look ahead for
- // their grammar. Currently there is no way to tell if an iterator is
- // pointing to forgotten data. The leading iterator will put an item in
- // the queue and remove one when it is incremented. No dynamic allocation
- // is done, except on creation of the queue (fixed_size_queue constructor).
- ///////////////////////////////////////////////////////////////////////////
- template <std::size_t N>
- struct fixed_size_queue
- {
- ///////////////////////////////////////////////////////////////////////
- template <typename Value>
- class unique : public detail::default_storage_policy
- {
- private:
- typedef detail::fixed_size_queue<Value, N> queue_type;
- protected:
- unique() {}
- unique(unique const& x)
- : queued_position(x.queued_position) {}
- void swap(unique& x)
- {
- boost::swap(queued_position, x.queued_position);
- }
- // This is called when the iterator is dereferenced. It's a
- // template method so we can recover the type of the multi_pass
- // iterator and access the m_input data member.
- template <typename MultiPass>
- static typename MultiPass::reference
- dereference(MultiPass const& mp)
- {
- if (!mp.queued_position.get_position().is_initialized())
- mp.queued_position.get_position().set_queue(&mp.shared()->queued_elements);
- if (mp.queued_position == mp.shared()->queued_elements.end())
- return MultiPass::get_input(mp);
- return *mp.queued_position;
- }
- // This is called when the iterator is incremented. It's a
- // template method so we can recover the type of the multi_pass
- // iterator and access the m_input data member.
- template <typename MultiPass>
- static void increment(MultiPass& mp)
- {
- if (!mp.queued_position.get_position().is_initialized())
- mp.queued_position.get_position().set_queue(&mp.shared()->queued_elements);
- if (mp.queued_position == mp.shared()->queued_elements.end())
- {
- // don't let the queue get larger than N
- if (mp.shared()->queued_elements.size() >= N)
- mp.shared()->queued_elements.pop_front();
- mp.shared()->queued_elements.push_back(
- MultiPass::get_input(mp));
- MultiPass::advance_input(mp);
- }
- ++mp.queued_position;
- }
- // clear_queue is a no-op
- // called to determine whether the iterator is an eof iterator
- template <typename MultiPass>
- static bool is_eof(MultiPass const& mp)
- {
- return mp.queued_position == mp.shared()->queued_elements.end() &&
- MultiPass::input_at_eof(mp);
- }
- // called by operator==
- template <typename MultiPass>
- static bool equal_to(MultiPass const& mp, MultiPass const& x)
- {
- return mp.queued_position == x.queued_position;
- }
- // called by operator<
- template <typename MultiPass>
- static bool less_than(MultiPass const& mp, MultiPass const& x)
- {
- return mp.queued_position < x.queued_position;
- }
- protected:
- mutable typename queue_type::iterator queued_position;
- };
- ///////////////////////////////////////////////////////////////////////
- template <typename Value>
- struct shared
- {
- typedef detail::fixed_size_queue<Value, N> queue_type;
- queue_type queued_elements;
- };
- };
- }}}
- #endif
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