public final Optional<DataType> traverse(
StepType tree, Operation op, Iterator<String> keys, DataType data) {
if (tree == null) {
return Optional.empty();
}
if (getStepType().isAssignableFrom(tree.getClass())) {
String key = keys.next();
if (child == null) {
// End of the Traversal so do the set or get
switch (op) {
case GET:
return this.get(tree, key);
case SET:
return (Optional<DataType>) traversr.handleFinalSet(this, tree, key, data);
case REMOVE:
return this.remove(tree, key);
default:
throw new IllegalStateException("Invalid op:" + op.toString());
}
} else {
// We just an intermediate step, so traverse and then hand over control to our child
Optional<Object> optSub = traversr.handleIntermediateGet(this, tree, key, op);
if (optSub.isPresent()) {
return child.traverse(optSub.get(), op, keys, data);
}
}
}
return Optional.empty();
}
/**
* This method is used when the TransposePathElement is used on the LFH as data.
*
* <p>Aka, normal "evaluate" returns either a Number or a String.
*
* @param walkedPath WalkedPath to evaluate against
* @return The data specified by this TransposePathElement.
*/
public Optional<Object> objectEvaluate(WalkedPath walkedPath) {
// Grap the data we need from however far up the tree we are supposed to go
PathStep pathStep = walkedPath.elementFromEnd(upLevel);
if (pathStep == null) {
return Optional.empty();
}
Object treeRef = pathStep.getTreeRef();
// Now walk down from that level using the subPathReader
if (subPathReader == null) {
return Optional.of(treeRef);
} else {
return subPathReader.read(treeRef, walkedPath);
}
}