+#ifdef __GXX_EXPERIMENTAL_CXX0X__
+ void
+ swap(queue&& __q)
+ { c.swap(__q.c); }
+#endif
+ };
+
+ /**
+ * @brief Queue equality comparison.
+ * @param x A %queue.
+ * @param y A %queue of the same type as @a x.
+ * @return True iff the size and elements of the queues are equal.
+ *
+ * This is an equivalence relation. Complexity and semantics depend on the
+ * underlying sequence type, but the expected rules are: this relation is
+ * linear in the size of the sequences, and queues are considered equivalent
+ * if their sequences compare equal.
+ */
+ template<typename _Tp, typename _Seq>
+ inline bool
+ operator==(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
+ { return __x.c == __y.c; }
+
+ /**
+ * @brief Queue ordering relation.
+ * @param x A %queue.
+ * @param y A %queue of the same type as @a x.
+ * @return True iff @a x is lexicographically less than @a y.
+ *
+ * This is an total ordering relation. Complexity and semantics
+ * depend on the underlying sequence type, but the expected rules
+ * are: this relation is linear in the size of the sequences, the
+ * elements must be comparable with @c <, and
+ * std::lexicographical_compare() is usually used to make the
+ * determination.
+ */
+ template<typename _Tp, typename _Seq>
+ inline bool
+ operator<(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
+ { return __x.c < __y.c; }
+
+ /// Based on operator==
+ template<typename _Tp, typename _Seq>
+ inline bool
+ operator!=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
+ { return !(__x == __y); }
+
+ /// Based on operator<
+ template<typename _Tp, typename _Seq>
+ inline bool
+ operator>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
+ { return __y < __x; }
+
+ /// Based on operator<
+ template<typename _Tp, typename _Seq>
+ inline bool
+ operator<=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
+ { return !(__y < __x); }
+
+ /// Based on operator<
+ template<typename _Tp, typename _Seq>
+ inline bool
+ operator>=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
+ { return !(__x < __y); }
+
+#ifdef __GXX_EXPERIMENTAL_CXX0X__
+ template<typename _Tp, typename _Seq>
+ inline void
+ swap(queue<_Tp, _Seq>& __x, queue<_Tp, _Seq>& __y)
+ { __x.swap(__y); }
+
+ template<typename _Tp, typename _Seq>
+ inline void
+ swap(queue<_Tp, _Seq>&& __x, queue<_Tp, _Seq>& __y)
+ { __x.swap(__y); }
+
+ template<typename _Tp, typename _Seq>
+ inline void
+ swap(queue<_Tp, _Seq>& __x, queue<_Tp, _Seq>&& __y)
+ { __x.swap(__y); }
+#endif
+
+ /**
+ * @brief A standard container automatically sorting its contents.
+ *
+ * @ingroup sequences
+ *
+ * This is not a true container, but an @e adaptor. It holds
+ * another container, and provides a wrapper interface to that
+ * container. The wrapper is what enforces priority-based sorting
+ * and %queue behavior. Very few of the standard container/sequence
+ * interface requirements are met (e.g., iterators).
+ *
+ * The second template parameter defines the type of the underlying
+ * sequence/container. It defaults to std::vector, but it can be
+ * any type that supports @c front(), @c push_back, @c pop_back,
+ * and random-access iterators, such as std::deque or an
+ * appropriate user-defined type.
+ *
+ * The third template parameter supplies the means of making
+ * priority comparisons. It defaults to @c less<value_type> but
+ * can be anything defining a strict weak ordering.
+ *
+ * Members not found in "normal" containers are @c container_type,
+ * which is a typedef for the second Sequence parameter, and @c
+ * push, @c pop, and @c top, which are standard %queue operations.
+ *
+ * @note No equality/comparison operators are provided for
+ * %priority_queue.
+ *
+ * @note Sorting of the elements takes place as they are added to,
+ * and removed from, the %priority_queue using the
+ * %priority_queue's member functions. If you access the elements
+ * by other means, and change their data such that the sorting
+ * order would be different, the %priority_queue will not re-sort
+ * the elements for you. (How could it know to do so?)
+ */
+ template<typename _Tp, typename _Sequence = vector<_Tp>,
+ typename _Compare = less<typename _Sequence::value_type> >
+ class priority_queue
+ {
+ // concept requirements
+ typedef typename _Sequence::value_type _Sequence_value_type;
+ __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
+ __glibcxx_class_requires(_Sequence, _SequenceConcept)
+ __glibcxx_class_requires(_Sequence, _RandomAccessContainerConcept)
+ __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
+ __glibcxx_class_requires4(_Compare, bool, _Tp, _Tp,
+ _BinaryFunctionConcept)
+
+ public:
+ typedef typename _Sequence::value_type value_type;
+ typedef typename _Sequence::reference reference;
+ typedef typename _Sequence::const_reference const_reference;
+ typedef typename _Sequence::size_type size_type;
+ typedef _Sequence container_type;
+
+ protected:
+ // See queue::c for notes on these names.
+ _Sequence c;
+ _Compare comp;
+
+ public:
+ /**
+ * @brief Default constructor creates no elements.
+ */
+#ifndef __GXX_EXPERIMENTAL_CXX0X__
+ explicit
+ priority_queue(const _Compare& __x = _Compare(),
+ const _Sequence& __s = _Sequence())
+ : c(__s), comp(__x)
+ { std::make_heap(c.begin(), c.end(), comp); }
+#else
+ explicit
+ priority_queue(const _Compare& __x,
+ const _Sequence& __s)
+ : c(__s), comp(__x)
+ { std::make_heap(c.begin(), c.end(), comp); }
+
+ explicit
+ priority_queue(const _Compare& __x = _Compare(),
+ _Sequence&& __s = _Sequence())
+ : c(std::move(__s)), comp(__x)
+ { std::make_heap(c.begin(), c.end(), comp); }
+#endif
+
+ /**
+ * @brief Builds a %queue from a range.
+ * @param first An input iterator.
+ * @param last An input iterator.
+ * @param x A comparison functor describing a strict weak ordering.
+ * @param s An initial sequence with which to start.
+ *
+ * Begins by copying @a s, inserting a copy of the elements
+ * from @a [first,last) into the copy of @a s, then ordering
+ * the copy according to @a x.
+ *
+ * For more information on function objects, see the
+ * documentation on @link functors functor base
+ * classes@endlink.
+ */
+#ifndef __GXX_EXPERIMENTAL_CXX0X__
+ template<typename _InputIterator>
+ priority_queue(_InputIterator __first, _InputIterator __last,
+ const _Compare& __x = _Compare(),
+ const _Sequence& __s = _Sequence())
+ : c(__s), comp(__x)
+ {
+ __glibcxx_requires_valid_range(__first, __last);
+ c.insert(c.end(), __first, __last);
+ std::make_heap(c.begin(), c.end(), comp);
+ }
+#else
+ template<typename _InputIterator>
+ priority_queue(_InputIterator __first, _InputIterator __last,
+ const _Compare& __x,
+ const _Sequence& __s)
+ : c(__s), comp(__x)
+ {
+ __glibcxx_requires_valid_range(__first, __last);
+ c.insert(c.end(), __first, __last);
+ std::make_heap(c.begin(), c.end(), comp);
+ }
+
+ template<typename _InputIterator>
+ priority_queue(_InputIterator __first, _InputIterator __last,
+ const _Compare& __x = _Compare(),
+ _Sequence&& __s = _Sequence())
+ : c(std::move(__s)), comp(__x)
+ {
+ __glibcxx_requires_valid_range(__first, __last);
+ c.insert(c.end(), __first, __last);
+ std::make_heap(c.begin(), c.end(), comp);
+ }
+
+ priority_queue(priority_queue&& __pq)
+ : c(std::move(__pq.c)), comp(std::move(__pq.comp)) { }
+
+ priority_queue&
+ operator=(priority_queue&& __pq)
+ {
+ c = std::move(__pq.c);
+ comp = std::move(__pq.comp);
+ return *this;
+ }
+#endif
+
+ /**
+ * Returns true if the %queue is empty.
+ */
+ bool
+ empty() const
+ { return c.empty(); }
+
+ /** Returns the number of elements in the %queue. */
+ size_type
+ size() const
+ { return c.size(); }
+
+ /**
+ * Returns a read-only (constant) reference to the data at the first
+ * element of the %queue.
+ */
+ const_reference
+ top() const
+ {
+ __glibcxx_requires_nonempty();
+ return c.front();
+ }