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Breadcrumbs go here --> <li><a href="modules.html">Modules</a></li> <li><a href="qtxmlpatterns.html">QtXmlPatterns</a></li> <li>QXmlResultItems</li> </ul> </div> <div class="toolbuttons toolblock"> <ul> <li id="smallA" class="t_button">A</li> <li id="medA" class="t_button active">A</li> <li id="bigA" class="t_button">A</li> <li id="print" class="t_button"><a href="javascript:this.print();"> <span>Print</span></a></li> </ul> </div> </div> <div class="content mainContent"> <div class="toc"> <h3><a name="toc">Contents</a></h3> <ul> <li class="level1"><a href="#public-functions">Public Functions</a></li> <li class="level1"><a href="#details">Detailed Description</a></li> </ul> </div> <h1 class="title">QXmlResultItems Class Reference</h1> <!-- $$$QXmlResultItems-brief --> <p>The QXmlResultItems class iterates through the results of evaluating an <a href="xmlprocessing.html">XQuery</a> in <a href="qxmlquery.html">QXmlQuery</a>. <a href="#details">More...</a></p> <!-- @@@QXmlResultItems --> <pre class="cpp"> <span class="preprocessor">#include <QXmlResultItems></span></pre><p><b>Note:</b> All functions in this class are <a href="threads-reentrancy.html#reentrant">reentrant</a>.</p> <p>This class was introduced in Qt 4.4.</p> <ul> <li><a href="qxmlresultitems-members.html">List of all members, including inherited members</a></li> </ul> <a name="public-functions"></a> <h2>Public Functions</h2> <table class="alignedsummary"> <tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qxmlresultitems.html#QXmlResultItems">QXmlResultItems</a></b> ()</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> virtual </td><td class="memItemRight bottomAlign"><b><a href="qxmlresultitems.html#dtor.QXmlResultItems">~QXmlResultItems</a></b> ()</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> QXmlItem </td><td class="memItemRight bottomAlign"><b><a href="qxmlresultitems.html#current">current</a></b> () const</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> bool </td><td class="memItemRight bottomAlign"><b><a href="qxmlresultitems.html#hasError">hasError</a></b> () const</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> QXmlItem </td><td class="memItemRight bottomAlign"><b><a href="qxmlresultitems.html#next">next</a></b> ()</td></tr> </table> <a name="details"></a> <!-- $$$QXmlResultItems-description --> <div class="descr"> <h2>Detailed Description</h2> <p>The QXmlResultItems class iterates through the results of evaluating an <a href="xmlprocessing.html">XQuery</a> in <a href="qxmlquery.html">QXmlQuery</a>.</p> <p>QXmlResultItems presents the evaluation of an associated query as a sequence of <a href="qxmlitem.html">QXmlItems</a>. The sequence is traversed by repeatedly calling <a href="qxmlresultitems.html#next">next</a>(), which actually produces the sequence by lazy evaluation of the query.</p> <pre class="cpp"> <span class="type"><a href="qxmlquery.html">QXmlQuery</a></span> query; query<span class="operator">.</span>setQuery(<span class="string">"<e/>, 1, 'two'"</span>); <span class="type">QXmlResultItems</span> result; <span class="keyword">if</span> (query<span class="operator">.</span>isValid()) { query<span class="operator">.</span>evaluateTo(<span class="operator">&</span>result); <span class="type"><a href="qxmlitem.html">QXmlItem</a></span> item(result<span class="operator">.</span>next()); <span class="keyword">while</span> (<span class="operator">!</span>item<span class="operator">.</span>isNull()) { <span class="comment">// use item</span> item <span class="operator">=</span> result<span class="operator">.</span>next(); } <span class="keyword">if</span> (result<span class="operator">.</span>hasError()) <span class="comment">/* Runtime error! */</span>; }</pre> <p>An effect of letting <a href="qxmlresultitems.html#next">next</a>() produce the sequence by lazy evaluation is that a query error can occur on any call to <a href="qxmlresultitems.html#next">next</a>(). If an error occurs, both <a href="qxmlresultitems.html#next">next</a>() and <a href="qxmlresultitems.html#current">current</a>() will return the null <a href="qxmlitem.html">QXmlItem</a>, and <a href="qxmlresultitems.html#hasError">hasError</a>() will return true.</p> <p>QXmlResultItems can be thought of as an "iterator" that traverses the sequence of query results once, in the forward direction. Each call to <a href="qxmlresultitems.html#next">next</a>() advances the iterator to the next <a href="qxmlitem.html">QXmlItem</a> in the sequence and returns it, and <a href="qxmlresultitems.html#current">current</a>() always returns the <a href="qxmlitem.html">QXmlItem</a> that <a href="qxmlresultitems.html#next">next</a>() returned the last time it was called.</p> <p><b>Note:</b> When using the QXmlResultItems overload of <a href="qxmlquery.html#evaluateTo">QXmlQuery::evaluateTo</a>() 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.</p> </div> <p><b>See also </b><a href="qxmlitem.html#isNode">QXmlItem::isNode</a>(), <a href="qxmlitem.html#isAtomicValue">QXmlItem::isAtomicValue</a>(), and <a href="qxmlnodemodelindex.html">QXmlNodeModelIndex</a>.</p> <!-- @@@QXmlResultItems --> <div class="func"> <h2>Member Function Documentation</h2> <!-- $$$QXmlResultItems[overload1]$$$QXmlResultItems --> <h3 class="fn"><a name="QXmlResultItems"></a>QXmlResultItems::<span class="name">QXmlResultItems</span> ()</h3> <p>Constructs an instance of <a href="qxmlresultitems.html">QXmlResultItems</a>.</p> <!-- @@@QXmlResultItems --> <!-- $$$~QXmlResultItems[overload1]$$$~QXmlResultItems --> <h3 class="fn"><a name="dtor.QXmlResultItems"></a>QXmlResultItems::<span class="name">~QXmlResultItems</span> ()<tt> [virtual]</tt></h3> <p>Destroys this instance of <a href="qxmlresultitems.html">QXmlResultItems</a>.</p> <!-- @@@~QXmlResultItems --> <!-- $$$current[overload1]$$$current --> <h3 class="fn"><a name="current"></a><span class="type"><a href="qxmlitem.html">QXmlItem</a></span> QXmlResultItems::<span class="name">current</span> () const</h3> <p>Returns the current item. The current item is the last item that was produced and returned by <a href="qxmlresultitems.html#next">next</a>().</p> <p>Returns a null <a href="qxmlitem.html">QXmlItem</a> if there is no associated <a href="qxmlquery.html">QXmlQuery</a>.</p> <!-- @@@current --> <!-- $$$hasError[overload1]$$$hasError --> <h3 class="fn"><a name="hasError"></a><span class="type">bool</span> QXmlResultItems::<span class="name">hasError</span> () const</h3> <p>If an error occurred during evaluation of the query, true is returned.</p> <p>Returns false if query evaluation has been done.</p> <!-- @@@hasError --> <!-- $$$next[overload1]$$$next --> <h3 class="fn"><a name="next"></a><span class="type"><a href="qxmlitem.html">QXmlItem</a></span> QXmlResultItems::<span class="name">next</span> ()</h3> <p>Returns the next result in the sequence produced by lazy evaluation of the associated query. When the returned <a href="qxmlitem.html">QXmlItem</a> is null, either the evaluation terminated normally without producing another result, or an error occurred. Call <a href="qxmlresultitems.html#hasError">hasError</a>() to determine whether the null item was caused by normal termination or by an error.</p> <p>Returns a null <a href="qxmlitem.html">QXmlItem</a> if there is no associated <a href="qxmlquery.html">QXmlQuery</a>.</p> <!-- @@@next --> </div> </div> </div> </div> <div class="ft"> <span></span> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2015 The Qt Company Ltd. 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