XPathEvaluator.java

package net.sourceforge.pmd.eclipse.ui.views.ast;

import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;

import net.sourceforge.pmd.RuleContext;
import net.sourceforge.pmd.RuleSet;
import net.sourceforge.pmd.RuleSets;
import net.sourceforge.pmd.lang.LanguageRegistry;
import net.sourceforge.pmd.lang.LanguageVersion;
import net.sourceforge.pmd.lang.LanguageVersionHandler;
import net.sourceforge.pmd.lang.Parser;
import net.sourceforge.pmd.lang.ast.Node;
import net.sourceforge.pmd.lang.java.JavaLanguageModule;
import net.sourceforge.pmd.lang.java.ast.ParseException;
import net.sourceforge.pmd.lang.rule.XPathRule;

/**
 * 
 * @author Brian Remedios
 */
public class XPathEvaluator {

	public static final XPathEvaluator instance = new XPathEvaluator();
	
	private XPathEvaluator() {}
	
	public Node getCompilationUnit(String source) {
		
		LanguageVersionHandler languageVersionHandler = getLanguageVersionHandler();
		Parser parser = languageVersionHandler.getParser(languageVersionHandler.getDefaultParserOptions());
		Node node = parser.parse(null, new StringReader(source));
		languageVersionHandler.getSymbolFacade().start(node);
		languageVersionHandler.getTypeResolutionFacade(null).start(node);
		return node;
	}

	private LanguageVersionHandler getLanguageVersionHandler() {
		LanguageVersion languageVersion = getLanguageVersion();
		return languageVersion.getLanguageVersionHandler();
	}

	private LanguageVersion getLanguageVersion() {
	    return LanguageRegistry.getLanguage(JavaLanguageModule.NAME).getDefaultVersion();
	}

	/**
	 * Builds a temporary XPathRule using the query provided and executes it against
	 * the source. Returns a list of nodes detailing any issues found with it.
	 * 
	 * @param source
	 * @param xpathQuery
	 * @param xpathVersion
	 * @return
	 * @throws ParseException
	 */
	public List<Node> evaluate(String source, String xpathQuery, String xpathVersion) throws ParseException {

		Node c = getCompilationUnit(source);

		final List<Node> results = new ArrayList<Node>();

		XPathRule xpathRule = new XPathRule() {
			public void addViolation(Object data, Node node, String arg) {
				results.add(node);
			}
		};
		
		xpathRule.setMessage("");
		xpathRule.setLanguage(getLanguageVersion().getLanguage());
		xpathRule.setProperty(XPathRule.XPATH_DESCRIPTOR, xpathQuery);
		xpathRule.setProperty(XPathRule.VERSION_DESCRIPTOR, xpathVersion);

		RuleSet ruleSet = new RuleSet();
		ruleSet.addRule(xpathRule);

		RuleSets ruleSets = new RuleSets(ruleSet);

		RuleContext ruleContext = new RuleContext();
		ruleContext.setLanguageVersion(getLanguageVersion());

		List<Node> nodes = new ArrayList<Node>(1);
		nodes.add(c);
		
		ruleSets.apply(nodes, ruleContext, xpathRule.getLanguage());

		return results;
	}
}