SpryEvaluateXPath

SpryEvaluateXPath.js

Spry.Data.XMLDataSet.evaluateXPath = function( contextNode, xpath ){
	var results = [],
		parser, i, length, tmp;
	
	// Quit processing if we don't even have sufficient data to process
	if( !( contextNode && xpath ) ) return results;
	
	// Check if the Google Xpath library is available. If it's included it's
	// usually an indication that user wants to use it as default.
	if( window.ExprContext && window.xpathParse ){
		results.concat( xpathParse( xpath ).evaluate( new ExprContext( contextNode ) ).nodeSetValue() );
		
		// if we have results, return 
		return results;
	}
	
	// Check if native technologies are available for parsing the xpath
	if( window.XSLTProcessor ){
		parser = ( new XPathEvaluator() ).evaluate( xpath, contextNode, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null );
		
		if( !!parser ){
			while( tmp = parser.iterateNext() ){
				results.push( tmp );
			}			
			
			// if we have results, return 
			return results;
		}
		
	}
	
	// And we can attempt to leverage IE technologies here 
	if( window.ActiveXObject ){
		parser = contextNode.selectNodes( xpath );
		if( !!parser ){
			for( i = 0, length = parser.length; i < length; i++ ){
				results.push( parser[i] );
			}
			
			// if we have results, return 
			return results;
		}
	}
	
	// The Google Xpath library is not available, and the native functions didn't 
	// produce any results. So we use Spry custom parser to handle 80% of the cases
	// The following paths are handled by the code below:
	//
	//   /gallery/photos/photo
	//   /gallery/photos/*
	//   gallery/photos/photo
	//   /gallery//photo
	//   //photo
	//   //photo/@path
	//   //photo/@*
	// Following code by the Spry Team with a small Chrome patch by Arnout Kazemier :)
	
	var ctx = [contextNode];
	var immediateChild = true;
	
	// We are forced to use new RegExp("\\/\\/?|[^\\/]+","g") instead of /\/\/?|[^\/]+/g due to a bug in Google Chrome
	var tknRegExp = new RegExp("\\/\\/?|[^\\/]+","g");
	var matches = tknRegExp.exec(xpath);
	while (matches)
	{
		var tkn = matches[0];
		if (tkn == "/" || tkn == "//") 
			immediateChild = (tkn == "/");
		else
		{
			var isAttr = (tkn.charAt(0) == "@");
			var nodeName = isAttr ? tkn.substr(1) : tkn;
			
			results = [];
			for (var i = 0; i < ctx.length; i++)
			{
				var cnode = ctx[i];
				var list = isAttr ? cnode.attributes : (immediateChild ? cnode.childNodes : cnode.getElementsByTagName(nodeName));
				for (var j = 0; j < list.length; j++)
				{
					var n = list[j];
					if ((!isAttr && !immediateChild) || ((n.nodeType == 1 || n.nodeType == 2) && (nodeName == "*" || n.nodeName == nodeName)))
						results.push(n);
				}
			}

			ctx = results;
		}

		matches = tknRegExp.exec(xpath);
	}
	
	
	// enough parsing already, time to return the results
	return results;
};

Chrome regexp issues fixed Trunk builds, it should land soon in regular Chrome versions; http://code.google.com/p/v8/issues/detail?id=704