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<h1 class="title">QXmlResultItems Class Reference</h1>
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<!-- $$$QXmlResultItems-brief -->
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<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>
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<!-- @@@QXmlResultItems -->
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<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>
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<p>This class was introduced in Qt 4.4.</p>
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<h2>Public Functions</h2>
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<table class="alignedsummary">
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<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qxmlresultitems.html#QXmlResultItems">QXmlResultItems</a></b> ()</td></tr>
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<tr><td class="memItemLeft rightAlign topAlign"> virtual </td><td class="memItemRight bottomAlign"><b><a href="qxmlresultitems.html#dtor.QXmlResultItems">~QXmlResultItems</a></b> ()</td></tr>
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<tr><td class="memItemLeft rightAlign topAlign"> QXmlItem </td><td class="memItemRight bottomAlign"><b><a href="qxmlresultitems.html#current">current</a></b> () const</td></tr>
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<tr><td class="memItemLeft rightAlign topAlign"> bool </td><td class="memItemRight bottomAlign"><b><a href="qxmlresultitems.html#hasError">hasError</a></b> () const</td></tr>
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<tr><td class="memItemLeft rightAlign topAlign"> QXmlItem </td><td class="memItemRight bottomAlign"><b><a href="qxmlresultitems.html#next">next</a></b> ()</td></tr>
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<a name="details"></a>
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<!-- $$$QXmlResultItems-description -->
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<div class="descr">
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<h2>Detailed Description</h2>
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<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>
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<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>
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<pre class="cpp"> <span class="type"><a href="qxmlquery.html">QXmlQuery</a></span> query;
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query<span class="operator">.</span>setQuery(<span class="string">"<e/>, 1, 'two'"</span>);
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<span class="type">QXmlResultItems</span> result;
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<span class="keyword">if</span> (query<span class="operator">.</span>isValid()) {
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query<span class="operator">.</span>evaluateTo(<span class="operator">&</span>result);
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<span class="type"><a href="qxmlitem.html">QXmlItem</a></span> item(result<span class="operator">.</span>next());
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<span class="keyword">while</span> (<span class="operator">!</span>item<span class="operator">.</span>isNull()) {
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<span class="comment">// use item</span>
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item <span class="operator">=</span> result<span class="operator">.</span>next();
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}
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<span class="keyword">if</span> (result<span class="operator">.</span>hasError())
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<span class="comment">/* Runtime error! */</span>;
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}</pre>
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<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>
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<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>
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<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>
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</div>
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<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>
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<!-- @@@QXmlResultItems -->
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<div class="func">
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<h2>Member Function Documentation</h2>
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<!-- $$$QXmlResultItems[overload1]$$$QXmlResultItems -->
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<h3 class="fn"><a name="QXmlResultItems"></a>QXmlResultItems::<span class="name">QXmlResultItems</span> ()</h3>
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<p>Constructs an instance of <a href="qxmlresultitems.html">QXmlResultItems</a>.</p>
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<!-- @@@QXmlResultItems -->
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<!-- $$$~QXmlResultItems[overload1]$$$~QXmlResultItems -->
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<h3 class="fn"><a name="dtor.QXmlResultItems"></a>QXmlResultItems::<span class="name">~QXmlResultItems</span> ()<tt> [virtual]</tt></h3>
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<p>Destroys this instance of <a href="qxmlresultitems.html">QXmlResultItems</a>.</p>
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<!-- @@@~QXmlResultItems -->
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<!-- $$$current[overload1]$$$current -->
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<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>
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<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>
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<p>Returns a null <a href="qxmlitem.html">QXmlItem</a> if there is no associated <a href="qxmlquery.html">QXmlQuery</a>.</p>
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<!-- @@@current -->
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<!-- $$$hasError[overload1]$$$hasError -->
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<h3 class="fn"><a name="hasError"></a><span class="type">bool</span> QXmlResultItems::<span class="name">hasError</span> () const</h3>
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<p>If an error occurred during evaluation of the query, true is returned.</p>
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<p>Returns false if query evaluation has been done.</p>
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<!-- @@@hasError -->
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<!-- $$$next[overload1]$$$next -->
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<h3 class="fn"><a name="next"></a><span class="type"><a href="qxmlitem.html">QXmlItem</a></span> QXmlResultItems::<span class="name">next</span> ()</h3>
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<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>
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<p>Returns a null <a href="qxmlitem.html">QXmlItem</a> if there is no associated <a href="qxmlquery.html">QXmlQuery</a>.</p>
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<!-- @@@next -->
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Documentation contributions included herein are the copyrights of
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