Custom pseudo classes and functions

Custom pseudo-class

Custom pseudo-classes extends the PseudoClass and implements match(Node node). This method should return true if a node is matched. You may also override the method getPseudoClassName() if you don't want to generate a pseudo-class name from the class name. For example:

public class MyPseudoClass extends PseudoClass {
    public boolean match(Node node) {
      return node.hasAttribute("jodd-attr");

    public String getPseudoClassName() {
      return "jodd";

Then register your pseudo-class with:


From that moment you will be able to find all nodes with the attribute jodd-attr using the :jodd pseudo-class.

When a pseudo-class needs to perform an additional match in the range of matched nodes (e.g. first, last etc), then override matchInRange() method, too.

Custom pseudo-function

Similar to pseudo-classes, custom pseudo-function implements the PseudoFunction class. Additionally, you need to also implement a method that parses input expression. This expression is later passed to the matching method.

Let's make a function that matches all nodes with certain name length:

public class MyPseudoFunction extends PseudoFunction {
    public Object parseExpression(String expression) {
        return Integer.valueOf(expression);

    public boolean match(Node node, Object expression) {
        Integer size = (Integer) expression;
        return node.getNodeName().length() == size.intValue();

    public String getPseudoFunctionName() {
        return "len-fn";

Register it with:


Start using it! E.g. :len-fn(3) to match all nodes with short names:)

Last updated