| /**************************************************************************** |
| ** |
| ** 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. |
| ** |
| ** $QT_END_LICENSE$ |
| ** |
| ****************************************************************************/ |
| |
| #include "qxmlresultitems.h" |
| #include "qxmlresultitems_p.h" |
| #include "qitem_p.h" |
| |
| QT_BEGIN_NAMESPACE |
| |
| /*! |
| \class QXmlResultItems |
| \brief The QXmlResultItems class iterates through the results of evaluating an XQuery in QXmlQuery. |
| \reentrant |
| \since 4.4 |
| \ingroup xml-tools |
| \inmodule QtXmlPatterns |
| |
| QXmlResultItems presents the evaluation of an associated query as a |
| sequence of \l{QXmlItem}{QXmlItems}. The sequence is traversed by |
| repeatedly calling next(), which actually produces the sequence by |
| lazy evaluation of the query. |
| |
| \snippet code/src_xmlpatterns_api_qxmlresultitems.cpp 0 |
| |
| An effect of letting next() produce the sequence by lazy evaluation |
| is that a query error can occur on any call to next(). If an error |
| occurs, both next() and current() will return the null QXmlItem, and |
| hasError() will return true. |
| |
| QXmlResultItems can be thought of as an "iterator" that traverses |
| the sequence of query results once, in the forward direction. Each |
| call to next() advances the iterator to the next QXmlItem in the |
| sequence and returns it, and current() always returns the QXmlItem |
| that next() returned the last time it was called. |
| |
| \note When using the QXmlResultItems overload of QXmlQuery::evaluateTo() |
| to execute a query, it is advisable to create a new instance of this |
| class for each new set of results rather than reusing an old instance. |
| |
| \sa QXmlItem::isNode(), QXmlItem::isAtomicValue(), QXmlNodeModelIndex |
| */ |
| |
| /*! |
| Constructs an instance of QXmlResultItems. |
| */ |
| QXmlResultItems::QXmlResultItems() : d_ptr(new QXmlResultItemsPrivate()) |
| { |
| } |
| |
| /*! |
| Destroys this instance of QXmlResultItems. |
| */ |
| QXmlResultItems::~QXmlResultItems() |
| { |
| } |
| |
| /*! |
| Returns the next result in the sequence produced by lazy evaluation |
| of the associated query. When the returned QXmlItem is null, either |
| the evaluation terminated normally without producing another result, |
| or an error occurred. Call hasError() to determine whether the null |
| item was caused by normal termination or by an error. |
| |
| Returns a null QXmlItem if there is no associated QXmlQuery. |
| */ |
| QXmlItem QXmlResultItems::next() |
| { |
| Q_D(QXmlResultItems); |
| if(d->hasError) |
| return QXmlItem(); |
| |
| try |
| { |
| d->current = QPatternist::Item::toPublic(d->iterator->next()); |
| return d->current; |
| } |
| catch(const QPatternist::Exception) |
| { |
| d->current = QXmlItem(); |
| d->hasError = true; |
| return QXmlItem(); |
| } |
| } |
| |
| /*! |
| Returns the current item. The current item is the last item |
| that was produced and returned by next(). |
| |
| Returns a null QXmlItem if there is no associated QXmlQuery. |
| */ |
| QXmlItem QXmlResultItems::current() const |
| { |
| Q_D(const QXmlResultItems); |
| |
| if(d->hasError) |
| return QXmlItem(); |
| else |
| return d->current; |
| } |
| |
| /*! |
| |
| If an error occurred during evaluation of the query, true is |
| returned. |
| |
| Returns false if query evaluation has been done. |
| */ |
| bool QXmlResultItems::hasError() const |
| { |
| Q_D(const QXmlResultItems); |
| return d->hasError; |
| } |
| |
| QT_END_NAMESPACE |
| |