/**************************************************************************** ** ** Copyright (C) 2016 The Qt Company Ltd. ** Contact: https://www.qt.io/licensing/ ** ** This file is part of the QtCore module of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:LGPL$ ** Commercial License Usage ** Licensees holding valid commercial Qt licenses may use this file in ** accordance with the commercial license agreement provided with the ** Software or, alternatively, in accordance with the terms contained in ** a written agreement between you and The Qt Company. For licensing terms ** and conditions see https://www.qt.io/terms-conditions. For further ** information use the contact form at https://www.qt.io/contact-us. ** ** GNU Lesser General Public License Usage ** Alternatively, this file may be used under the terms of the GNU Lesser ** General Public License version 3 as published by the Free Software ** Foundation and appearing in the file LICENSE.LGPL3 included in the ** packaging of this file. Please review the following information to ** ensure the GNU Lesser General Public License version 3 requirements ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. ** ** GNU General Public License Usage ** Alternatively, this file may be used under the terms of the GNU ** General Public License version 2.0 or (at your option) the GNU General ** Public license version 3 or any later version approved by the KDE Free ** Qt Foundation. The licenses are as published by the Free Software ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 ** included in the packaging of this file. Please review the following ** information to ensure the GNU General Public License requirements will ** be met: https://www.gnu.org/licenses/gpl-2.0.html and ** https://www.gnu.org/licenses/gpl-3.0.html. ** ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \class QStack \inmodule QtCore \brief The QStack class is a template class that provides a stack. \ingroup tools \ingroup shared \reentrant QStack\ is one of Qt's generic \l{container classes}. It implements a stack data structure for items of a same type. A stack is a last in, first out (LIFO) structure. Items are added to the top of the stack using push() and retrieved from the top using pop(). The top() function provides access to the topmost item without removing it. Example: \snippet qstack/main.cpp 0 The example will output 3, 2, 1 in that order. QStack inherits from QVector. All of QVector's functionality also applies to QStack. For example, you can use isEmpty() to test whether the stack is empty, and you can traverse a QStack using QVector's iterator classes (for example, QVectorIterator). But in addition, QStack provides three convenience functions that make it easy to implement LIFO semantics: push(), pop(), and top(). QStack's value type must be an \l{assignable data type}. This covers most data types that are commonly used, but the compiler won't let you, for example, store a QWidget as a value; instead, store a QWidget *. \sa QVector, QQueue */ /*! \fn template void QStack::swap(QStack &other) \since 4.8 Swaps stack \a other with this stack. This operation is very fast and never fails. */ /*! \fn template void QStack::push(const T& t) Adds element \a t to the top of the stack. This is the same as QVector::append(). \sa pop(), top() */ /*! \fn template T& QStack::top() Returns a reference to the stack's top item. This function assumes that the stack isn't empty. This is the same as QVector::last(). \sa pop(), push(), isEmpty() */ /*! \fn template const T& QStack::top() const \overload \sa pop(), push() */ /*! \fn template T QStack::pop() Removes the top item from the stack and returns it. This function assumes that the stack isn't empty. \sa top(), push(), isEmpty() */