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/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtXmlPatterns 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.
**
** $QT_END_LICENSE$
**
****************************************************************************/

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.

#ifndef Patternist_Focus_H
#define Patternist_Focus_H

#include <private/qdelegatingdynamiccontext_p.h>

QT_BEGIN_NAMESPACE

namespace QPatternist
{
    /**
     * @short A DynamicContext that maintains the focus, a sequence
     * of items.
     *
     * Focus implements both the outer and inner focus. The focus is one of
     * the things that characterizes the XPath language. The focus is what's
     * iterated over in a predicate, whose current item can be received
     * via the context item expression, <tt>.</tt>(the dot),
     * and whose size is retrievable via the function <tt>fn:last()</tt>.
     *
     * @author Frans Englich <frans.englich@nokia.com>
     */
    class Focus : public DelegatingDynamicContext
    {
    public:
        Focus(const DynamicContext::Ptr &prevContext);

        xsInteger contextPosition() const override;
        Item contextItem() const override;
        xsInteger contextSize() override;

        void setFocusIterator(const Item::Iterator::Ptr &it) override;
        Item::Iterator::Ptr focusIterator() const override;

        /**
         * If there is no top level expression that sets the current item,
         * the focus should be used. This implementation ensures that.
         */
        Item currentItem() const override;

    private:
        Item::Iterator::Ptr m_focusIterator;
        xsInteger           m_contextSizeCached;
    };
}

QT_END_NAMESPACE

#endif