code: Node compile(final Object root)
  	{
  		if (compiled == null)
  		{
  			compiled = compileExpression(root, this.expr);
  			parsed = null;
  
  			if (this.notifyOnCompiled != null)
  				this.notifyOnCompiled.accept(this.expr, this);
  		}
  
  		return compiled;
  	}
docs: Eagerly compile this OGNL expression
  
  @param root
  
  @return