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Diffstat (limited to 'src/xmlpatterns/api/qxmlresultitems.cpp')
-rw-r--r-- | src/xmlpatterns/api/qxmlresultitems.cpp | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/src/xmlpatterns/api/qxmlresultitems.cpp b/src/xmlpatterns/api/qxmlresultitems.cpp new file mode 100644 index 0000000..4d167d0 --- /dev/null +++ b/src/xmlpatterns/api/qxmlresultitems.cpp @@ -0,0 +1,152 @@ +/**************************************************************************** +** +** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the QtXmlPatterns module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the Technology Preview License Agreement accompanying +** this package. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain additional +** rights. These rights are described in the Nokia Qt LGPL Exception +** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. +** +** If you have questions regarding the use of this file, please contact +** Nokia at qt-info@nokia.com. +** +** +** +** +** +** +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#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 + + 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 doc/src/snippets/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 + |