// Copyright (C) 2004-2006 The Trustees of Indiana University.
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// Use, modification and distribution is subject to the Boost Software
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// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// Authors: Douglas Gregor
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// Andrew Lumsdaine
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#ifndef BOOST_FILTERED_QUEUE_HPP
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#define BOOST_FILTERED_QUEUE_HPP
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#ifndef BOOST_GRAPH_USE_MPI
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#error "Parallel BGL files should not be included unless <boost/graph/use_mpi.hpp> has been included"
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#endif
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#include <algorithm>
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namespace boost {
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/** Queue adaptor that filters elements pushed into the queue
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* according to some predicate.
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*/
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template<typename Buffer, typename Predicate>
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class filtered_queue
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{
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public:
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typedef Buffer buffer_type;
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typedef Predicate predicate_type;
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typedef typename Buffer::value_type value_type;
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typedef typename Buffer::size_type size_type;
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/**
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* Constructs a new filtered queue with an initial buffer and a
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* predicate.
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*
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* @param buffer the initial buffer
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* @param pred the predicate
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*/
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explicit
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filtered_queue(const buffer_type& buffer = buffer_type(),
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const predicate_type& pred = predicate_type())
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: buffer(buffer), pred(pred) {}
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/** Push a value into the queue.
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*
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* If the predicate returns @c true for @p x, pushes @p x into the
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* buffer.
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*/
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void push(const value_type& x) { if (pred(x)) buffer.push(x); }
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/** Pop the front element off the buffer.
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*
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* @pre @c !empty()
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*/
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void pop() { buffer.pop(); }
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/** Retrieve the front (top) element in the buffer.
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*
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* @pre @c !empty()
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*/
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value_type& top() { return buffer.top(); }
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/**
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* \overload
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*/
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const value_type& top() const { return buffer.top(); }
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/** Determine the number of elements in the buffer. */
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size_type size() const { return buffer.size(); }
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/** Determine if the buffer is empty. */
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bool empty() const { return buffer.empty(); }
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/** Get a reference to the underlying buffer. */
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buffer_type& base() { return buffer; }
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const buffer_type& base() const { return buffer; }
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/** Swap the contents of this with @p other. */
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void swap(filtered_queue& other)
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{
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using std::swap;
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swap(buffer, other.buffer);
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swap(pred, other.pred);
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}
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private:
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buffer_type buffer;
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predicate_type pred;
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};
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/** Create a filtered queue. */
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template<typename Buffer, typename Predicate>
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inline filtered_queue<Buffer, Predicate>
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make_filtered_queue(const Buffer& buffer, const Predicate& pred)
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{ return filtered_queue<Buffer, Predicate>(buffer, pred); }
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/** Swap a filtered_queue. */
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template<typename Buffer, typename Predicate>
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inline void
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swap(filtered_queue<Buffer, Predicate>& x,
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filtered_queue<Buffer, Predicate>& y)
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{
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x.swap(y);
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}
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} // end namespace boost
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#endif // BOOST_FILTERED_QUEUE_HPP
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