/**
* Traverses itself and child expressions, notifying visitor via callback methods as it goes. This
* is an Expression-specific implementation of the "Visitor" design pattern.
*
* @since 1.1
*/
public void traverse(TraversalHandler visitor) {
if (visitor == null) {
throw new NullPointerException("Null Visitor.");
}
traverse(null, visitor);
}
/**
* Traverses itself and child expressions, notifying visitor via callback methods as it goes.
*
* @since 1.1
*/
protected void traverse(Expression parentExp, TraversalHandler visitor) {
visitor.startNode(this, parentExp);
// recursively traverse each child
int count = getOperandCount();
for (int i = 0; i < count; i++) {
Object child = getOperand(i);
if (child instanceof Expression) {
Expression childExp = (Expression) child;
childExp.traverse(this, visitor);
} else {
visitor.objectNode(child, this);
}
visitor.finishedChild(this, i, i < count - 1);
}
visitor.endNode(this, parentExp);
}