// Copyright (C) 2016 The Qt Company Ltd. // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only /*! \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 QList. All of QList'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 QList's iterator classes (for example, QListIterator). 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 QList, 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 QList::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 QList::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() */