stack（堆栈） 其实是一个容器类做的修改，提供了堆栈的全部功能，实现了一个先进后出（FILO）的数据结构。
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// Stack implementation -*- C++ -*- // Copyright (C) 2001, 2002, 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_stack.h * This is an internal header file, included by other library headers. * You should not attempt to use it directly. */ #ifndef _STACK_H #define _STACK_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 stack; template<typename _Tp, typename _Seq> inline bool operator==(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y); template<typename _Tp, typename _Seq> inline bool operator<(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y); /** * @brief A standard container giving FILO 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-last-out %stack 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 back, @c push_back, and @c pop_front, * such as std::list, std::vector, 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, @c pop, and @c top, which are standard %stack/FILO * operations. */ template<typename _Tp, typename _Sequence> class stack { // concept requirements typedef typename _Sequence::value_type _Sequence_value_type; __glibcxx_class_requires(_Tp, _SGIAssignableConcept) __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept) __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept) template<typename _Tp1, typename _Seq1> friend bool operator==(const stack<_Tp1, _Seq1>&, const stack<_Tp1, _Seq1>&); template<typename _Tp1, typename _Seq1> friend bool operator<(const stack<_Tp1, _Seq1>&, const stack<_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: // See queue::c for notes on this name. _Sequence c; public: // XXX removed old def ctor, added def arg to this one to match 14882 /** * @brief Default constructor creates no elements. */ explicit stack(const _Sequence& __c = _Sequence()) : c(__c) {} /** * Returns true if the %stack is empty. */ bool empty() const { return c.empty(); } /** Returns the number of elements in the %stack. */ size_type size() const { return c.size(); } /** * Returns a read/write reference to the data at the first * element of the %stack. */ reference top() { __glibcxx_requires_nonempty(); return c.back(); } /** * Returns a read-only (constant) reference to the data at the first * element of the %stack. */ const_reference top() const { __glibcxx_requires_nonempty(); return c.back(); } /** * @brief Add data to the top of the %stack. * @param x Data to be added. * * This is a typical %stack operation. The function creates an * element at the top of the %stack 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 %stack operation. It shrinks the %stack * 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_back(); } }; /** * @brief Stack equality comparison. * @param x A %stack. * @param y A %stack of the same type as @a x. * @return True iff the size and elements of the stacks 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 * stacks are considered equivalent if their sequences compare * equal. */ template<typename _Tp, typename _Seq> inline bool operator==(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) { return __x.c == __y.c; } /** * @brief Stack ordering relation. * @param x A %stack. * @param y A %stack 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 stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) { return __x.c < __y.c; } /// Based on operator== template<typename _Tp, typename _Seq> inline bool operator!=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) { return !(__x == __y); } /// Based on operator< template<typename _Tp, typename _Seq> inline bool operator>(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) { return __y < __x; } /// Based on operator< template<typename _Tp, typename _Seq> inline bool operator<=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) { return !(__y < __x); } /// Based on operator< template<typename _Tp, typename _Seq> inline bool operator>=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y) { return !(__x < __y); } } // namespace std #endif /* _STACK_H */ |