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POCan I make this xpath search faster?
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  1. POCan I make this xpath search faster?
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    copied!<p>xml:</p> <p><code> &lt;root&gt;<br/> &nbsp;&lt;a&nbsp;auto='1'&gt;<br/> &nbsp;&nbsp;&lt;b&gt;<br/> &nbsp;&nbsp;&nbsp;&lt;c auto="1"&gt;<br/> &nbsp;&nbsp;&nbsp;&nbsp;&lt;d auto="1"&gt;&lt;/d&gt;<br/> &nbsp;&nbsp;&nbsp;&lt;/c&gt;<br/> &nbsp;&nbsp;&lt;/b&gt;<br/> &nbsp;&nbsp;&lt;e auto="1"&gt;<br/> &nbsp;&nbsp;&nbsp;&lt;f&gt;<br/> &nbsp;&nbsp;&nbsp;&nbsp;&lt;g auto="1"&gt;&lt;/g&gt;<br/> &nbsp;&nbsp;&nbsp;&lt;/f&gt;<br/> &nbsp;&nbsp;&lt;/e&gt;<br/> &nbsp;&lt;/a&gt;<br/> &lt;/root&gt;<br/> </code> <br/></p> <p>The job is: find all elements that:<br/> 1, Is descendant of context element<br/> 2, Have '<strong>auto</strong>' attribute<br/> 3, Highest level (have no ancestor <strong>with auto attribute</strong> between self and the context element)<br/></p> <p>So, if the context node is <strong>a</strong>, <strong>c</strong> and <strong>e</strong> should be returned.<br/></p> <p>I'v implement it in my php class:<br/> <code> $tempId='XDFAY69LA';<br/> $this->setAttribute('tempId',$tempId);<br/> $path=".//*[@auto and not(ancestor::*[@auto and ancestor::*[@tempId='$tempId']])]";<br/> $ar=$this->getElementsByXPath($path);<br/> $this->removeAttribute('tempId');<br/> </code> <br/> But I found the query is slowly, maybe .. , because the query is too complex?, And is there a way that do a better job?</p> <p><strong>I'v write a testing, plz have a look:</strong></p> <pre> &lt;?php $xml=' &lt;root&gt; &lt;a auto="1" tempId="current"&gt; &lt;b&gt; &lt;c auto="1"&gt; &lt;d auto="1"&gt;&lt;/d&gt; &lt;/c&gt; &lt;/b&gt; &lt;e auto="1"&gt; &lt;f&gt; &lt;g auto="1"&gt;&lt;/g&gt; &lt;/f&gt; &lt;/e&gt; &lt;/a&gt; &lt;/root&gt; '; $doc=new DomDocument(); $tempId='XDFAY69LA'; $doc-&gt;loadXml($xml); $domxpath=new DOMXPath($doc); $a=$domxpath-&gt;query('a')-&gt;item(0); $path=".//*[@auto and not(ancestor::*[@auto and ancestor::*[@tempId='$tempId']])]"; $start=microtime(true); for($n=0;$n&lt;1000;$n++){ //run 1000 times $a-&gt;setAttribute('tempId',$tempId); $ar=$domxpath-&gt;query($path,$a); $a-&gt;removeAttribute('tempId'); for($i=0;$i&lt;$ar-&gt;length;$i++){ $node=$ar-&gt;item($i); //echo $node-&gt;tagName . "\n"; } } $cost=round(1000 * (microtime(true)-$start)); echo "time cost: $cost"; ?&gt; </pre>
 

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