this.variables.add(pc.stylesheet);
if (this.parameters != null) {
String[] name = this.parameters.getNames();
for (int i=0; i < name.length; ++i) {
try {
VariableResolver resolver =
this.variableFactory.lookup(this.parameters.getParameter(name[i]));
this.variables.add(resolver);
pc.parameters.put(name[i], resolver);
} catch (PatternException e) {
throw new ParameterException("Invalid value for parameter " + name[i], e);