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<td >Qt 5.9</td><td ><a href="qtxmlpatterns-index.html">Qt XML Patterns</a></td><td ><a href="qtxmlpatterns-module.html">C++ Classes</a></td><td >QXmlResultItems</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right">Qt 5.9.4 Reference Documentation</td>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">QXmlResultItems Class</h1>
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<p>The <a href="qxmlresultitems.html">QXmlResultItems</a> 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 -->
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<tr><td class="memItemLeft rightAlign topAlign"> Header:</td><td class="memItemRight bottomAlign"> <span class="preprocessor">#include <QXmlResultItems></span>
</td></tr><tr><td class="memItemLeft rightAlign topAlign"> qmake:</td><td class="memItemRight bottomAlign"> QT += xmlpatterns</td></tr><tr><td class="memItemLeft rightAlign topAlign"> Since:</td><td class="memItemRight bottomAlign"> Qt 4.4</td></tr></table></div><ul>
<li><a href="qxmlresultitems-members.html">List of all members, including inherited members</a></li>
</ul>
<p><b>Note:</b> All functions in this class are reentrant.</p>
<a name="public-functions"></a>
<h2 id="public-functions">Public Functions</h2>
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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>
<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>
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<a name="details"></a>
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<h2 id="details">Detailed Description</h2>
<p>The <a href="qxmlresultitems.html">QXmlResultItems</a> class iterates through the results of evaluating an <a href="xmlprocessing.html">XQuery</a> in <a href="qxmlquery.html">QXmlQuery</a>.</p>
<p><a href="qxmlresultitems.html">QXmlResultItems</a> 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"><a href="qxmlresultitems.html#QXmlResultItems">QXmlResultItems</a></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><a href="qxmlresultitems.html">QXmlResultItems</a> 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 <a href="qxmlresultitems.html">QXmlResultItems</a> 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" id="QXmlResultItems"><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" id="dtor.QXmlResultItems"><a name="dtor.QXmlResultItems"></a><code>[virtual] </code>QXmlResultItems::<span class="name">~QXmlResultItems</span>()</h3>
<p>Destroys this instance of <a href="qxmlresultitems.html">QXmlResultItems</a>.</p>
<!-- @@@~QXmlResultItems -->
<!-- $$$current[overload1]$$$current -->
<h3 class="fn" id="current"><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" id="hasError"><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" id="next"><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 -->
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