队列queue，先进先出(FIFO)的数据结构。queue头文件中定义了，queue队列和priority_queues优先队列（优先队列就是入队时自动会排序）
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// Queue implementation -*- C++ -*- // Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 2, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License along // with this library; see the file COPYING. If not, write to the Free // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, // USA. // As a special exception, you may use this file as part of a free software // library without restriction. Specifically, if other files instantiate // templates or use macros or inline functions from this file, or you compile // this file and link it with other files to produce an executable, this // file does not by itself cause the resulting executable to be covered by // the GNU General Public License. This exception does not however // invalidate any other reasons why the executable file might be covered by // the GNU General Public License. /* * * Copyright (c) 1994 * Hewlett-Packard Company * * Permission to use, copy, modify, distribute and sell this software * and its documentation for any purpose is hereby granted without fee, * provided that the above copyright notice appear in all copies and * that both that copyright notice and this permission notice appear * in supporting documentation. Hewlett-Packard Company makes no * representations about the suitability of this software for any * purpose. It is provided "as is" without express or implied warranty. * * * Copyright (c) 1996,1997 * Silicon Graphics Computer Systems, Inc. * * Permission to use, copy, modify, distribute and sell this software * and its documentation for any purpose is hereby granted without fee, * provided that the above copyright notice appear in all copies and * that both that copyright notice and this permission notice appear * in supporting documentation. Silicon Graphics makes no * representations about the suitability of this software for any * purpose. It is provided "as is" without express or implied warranty. */ /** @file stl_queue.h * This is an internal header file, included by other library headers. * You should not attempt to use it directly. */ #ifndef _QUEUE_H #define _QUEUE_H 1 #include <bits/concept_check.h> #include <debug/debug.h> namespace std { // Forward declarations of operators < and ==, needed for friend declaration. template<typename _Tp, typename _Sequence = deque<_Tp> > class queue; template<typename _Tp, typename _Seq> inline bool operator==(const queue<_Tp,_Seq>&, const queue<_Tp,_Seq>&); template<typename _Tp, typename _Seq> inline bool operator<(const queue<_Tp,_Seq>&, const queue<_Tp,_Seq>&); /** * @brief A standard container giving FIFO behavior. * * @ingroup Containers * @ingroup Sequences * * Meets many of the requirements of a * <a href="tables.html#65">container</a>, * but does not define anything to do with iterators. Very few of the * other standard container interfaces are defined. * * 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 strict first-in-first-out %queue behavior. * * The second template parameter defines the type of the underlying * sequence/container. It defaults to std::deque, but it can be any type * that supports @c front, @c back, @c push_back, and @c pop_front, * such as std::list or an appropriate user-defined type. * * Members not found in "normal" containers are @c container_type, * which is a typedef for the second Sequence parameter, and @c push and * @c pop, which are standard %queue/FIFO operations. */ template<typename _Tp, typename _Sequence> class queue { // concept requirements typedef typename _Sequence::value_type _Sequence_value_type; __glibcxx_class_requires(_Tp, _SGIAssignableConcept) __glibcxx_class_requires(_Sequence, _FrontInsertionSequenceConcept) __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept) __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept) template<typename _Tp1, typename _Seq1> friend bool operator==(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&); template<typename _Tp1, typename _Seq1> friend bool operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&); 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: /** * 'c' is the underlying container. Maintainers wondering why * this isn't uglified as per style guidelines should note that * this name is specified in the standard, [23.2.3.1]. (Why? * Presumably for the same reason that it's protected instead * of private: to allow derivation. But none of the other * containers allow for derivation. Odd.) */ _Sequence c; public: /** * @brief Default constructor creates no elements. */ explicit queue(const _Sequence& __c = _Sequence()) : c(__c) {} /** * 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/write reference to the data at the first * element of the %queue. */ reference front() { __glibcxx_requires_nonempty(); return c.front(); } /** * Returns a read-only (constant) reference to the data at the first * element of the %queue. */ const_reference front() const { __glibcxx_requires_nonempty(); return c.front(); } /** * Returns a read/write reference to the data at the last * element of the %queue. */ reference back() { __glibcxx_requires_nonempty(); return c.back(); } /** * Returns a read-only (constant) reference to the data at the last * element of the %queue. */ const_reference back() const { __glibcxx_requires_nonempty(); return c.back(); } /** * @brief Add data to the end of the %queue. * @param x Data to be added. * * This is a typical %queue operation. The function creates an * element at the end of the %queue and assigns the given data * to it. The time complexity of the operation depends on the * underlying sequence. */ void push(const value_type& __x) { c.push_back(__x); } /** * @brief Removes first element. * * This is a typical %queue operation. It shrinks the %queue by one. * The time complexity of the operation depends on the underlying * sequence. * * Note that no data is returned, and if the first element's * data is needed, it should be retrieved before pop() is * called. */ void pop() { __glibcxx_requires_nonempty(); c.pop_front(); } }; /** * @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 _Sequence> inline bool operator==(const queue<_Tp,_Sequence>& __x, const queue<_Tp,_Sequence>& __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 _Sequence> inline bool operator<(const queue<_Tp,_Sequence>& __x, const queue<_Tp,_Sequence>& __y) { return __x.c < __y.c; } /// Based on operator== template<typename _Tp, typename _Sequence> inline bool operator!=(const queue<_Tp,_Sequence>& __x, const queue<_Tp,_Sequence>& __y) { return !(__x == __y); } /// Based on operator< template<typename _Tp, typename _Sequence> inline bool operator>(const queue<_Tp,_Sequence>& __x, const queue<_Tp,_Sequence>& __y) { return __y < __x; } /// Based on operator< template<typename _Tp, typename _Sequence> inline bool operator<=(const queue<_Tp,_Sequence>& __x, const queue<_Tp,_Sequence>& __y) { return !(__y < __x); } /// Based on operator< template<typename _Tp, typename _Sequence> inline bool operator>=(const queue<_Tp,_Sequence>& __x, const queue<_Tp,_Sequence>& __y) { return !(__x < __y); } /** * @brief A standard container automatically sorting its contents. * * @ingroup Containers * @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 sorting and * first-in-first-out %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/FIFO * 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. */ explicit priority_queue(const _Compare& __x = _Compare(), const _Sequence& __s = _Sequence()) : c(__s), comp(__x) { std::make_heap(c.begin(), c.end(), comp); } /** * @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 s20_3_1_base functor base * classes@endlink. */ 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); } /** * 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(); } /** * @brief Add data to the %queue. * @param x Data to be added. * * This is a typical %queue operation. * The time complexity of the operation depends on the underlying * sequence. */ void push(const value_type& __x) { try { c.push_back(__x); std::push_heap(c.begin(), c.end(), comp); } catch(...) { c.clear(); __throw_exception_again; } } /** * @brief Removes first element. * * This is a typical %queue operation. It shrinks the %queue * by one. The time complexity of the operation depends on the * underlying sequence. * * Note that no data is returned, and if the first element's * data is needed, it should be retrieved before pop() is * called. */ void pop() { __glibcxx_requires_nonempty(); try { std::pop_heap(c.begin(), c.end(), comp); c.pop_back(); } catch(...) { c.clear(); __throw_exception_again; } } }; // No equality/comparison operators are provided for priority_queue. } // namespace std #endif /* _QUEUE_H */ |