package org.simantics.r.scl.variable;

import org.rosuda.REngine.REXP;
import org.rosuda.REngine.REXPMismatchException;
import org.rosuda.REngine.RList;

public class RListItemNode implements RVariableNode {

	private RVariableNode parent;
	private int index;
	
	public RListItemNode(RVariableNode parent, int index) {
		this.index = index;
		this.parent = parent;
	}

	@Override
	public REXP getValue() {
		REXP parentValue = parent.getValue();
		if (parentValue == null || ! parentValue.isList())
			return null;
		
		RList list;
		try {
			list = parentValue.asList();
		} catch (REXPMismatchException e) {
			// Should never happen
			return null;
		}
		
		return list.at(index);
	}

	@Override
	public String getName() {
		return RNodeManager.INDEXED_ITEM_NAME_PREFIX + Integer.toString(index);
	}

	@Override
	public RVariableNode getParent() {
		return parent;
	}
}