XPathRule.java example

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/**
 * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
 */

package net.sourceforge.pmd.lang.rule;

import static net.sourceforge.pmd.lang.rule.xpath.XPathRuleQuery.XPATH_1_0;
import static net.sourceforge.pmd.lang.rule.xpath.XPathRuleQuery.XPATH_1_0_COMPATIBILITY;
import static net.sourceforge.pmd.lang.rule.xpath.XPathRuleQuery.XPATH_2_0;

import java.util.List;

import net.sourceforge.pmd.PropertySource;
import net.sourceforge.pmd.RuleContext;
import net.sourceforge.pmd.lang.ast.Node;
import net.sourceforge.pmd.lang.rule.properties.EnumeratedProperty;
import net.sourceforge.pmd.lang.rule.properties.StringProperty;
import net.sourceforge.pmd.lang.rule.xpath.JaxenXPathRuleQuery;
import net.sourceforge.pmd.lang.rule.xpath.SaxonXPathRuleQuery;
import net.sourceforge.pmd.lang.rule.xpath.XPathRuleQuery;
import net.sourceforge.pmd.util.StringUtil;

/**
 * Rule that tries to match an XPath expression against a DOM view of an AST.
 * 
 * This rule needs a "xpath" property value in order to function.
 */
public class XPathRule extends AbstractRule {

    public static final StringProperty XPATH_DESCRIPTOR = new StringProperty("xpath", "XPath expression", "", 1.0f);
    public static final EnumeratedProperty<String> VERSION_DESCRIPTOR = new EnumeratedProperty<>("version",
            "XPath specification version", new String[] { XPATH_1_0, XPATH_1_0_COMPATIBILITY, XPATH_2_0 },
            new String[] { XPATH_1_0, XPATH_1_0_COMPATIBILITY, XPATH_2_0 }, 0, 2.0f);

    private XPathRuleQuery xpathRuleQuery;

    public XPathRule() {
        definePropertyDescriptor(XPATH_DESCRIPTOR);
        definePropertyDescriptor(VERSION_DESCRIPTOR);
    }

    public XPathRule(String xPath) {
        this();
        setXPath(xPath);
    }

    public void setXPath(String xPath) {
        setProperty(XPathRule.XPATH_DESCRIPTOR, xPath);
    }

    public void setVersion(String version) {
        setProperty(XPathRule.VERSION_DESCRIPTOR, version);
    }

    /**
     * Apply the rule to all nodes.
     */
    @Override
    public void apply(List<? extends Node> nodes, RuleContext ctx) {
        for (Node node : nodes) {
            evaluate(node, ctx);
        }
    }

    /**
     * Evaluate the XPath query with the AST node. All matches are reported as
     * violations.
     *
     * @param node
     *            The Node that to be checked.
     * @param data
     *            The RuleContext.
     */
    public void evaluate(Node node, RuleContext data) {
        init();
        List<Node> nodes = xpathRuleQuery.evaluate(node, data);
        if (nodes != null) {
            for (Node n : nodes) {
                addViolation(data, n, n.getImage());
            }
        }

    }

    @Override
    public List<String> getRuleChainVisits() {
        if (init()) {
            for (String nodeName : xpathRuleQuery.getRuleChainVisits()) {
                super.addRuleChainVisit(nodeName);
            }
        }
        return super.getRuleChainVisits();
    }

    private boolean init() {
        if (xpathRuleQuery == null) {
            String xpath = getProperty(XPATH_DESCRIPTOR);
            String version = (String) getProperty(VERSION_DESCRIPTOR);
            if (XPATH_1_0.equals(version)) {
                xpathRuleQuery = new JaxenXPathRuleQuery();
            } else {
                xpathRuleQuery = new SaxonXPathRuleQuery();
            }
            xpathRuleQuery.setXPath(xpath);
            xpathRuleQuery.setVersion(version);
            xpathRuleQuery.setProperties(this.getPropertiesByPropertyDescriptor());
            return true;
        }
        return false;
    }

    public boolean hasXPathExpression() {
        String xPath = getProperty(XPATH_DESCRIPTOR);
        return StringUtil.isNotEmpty(xPath);
    }

    /**
     * @see PropertySource#dysfunctionReason()
     */
    @Override
    public String dysfunctionReason() {
        return hasXPathExpression() ? null : "Missing xPath expression";
    }
}