notfoundvalue.java

是有关解释器的.用JAVA编写.可以解释一般的JAVA程序.

/**
 * Placeholder class to represent a "not found value". An instance of this class
 * is returned by <code>at(String)</code> (class Environment) if the value for
 * the given key is not found.
 * 
 * @see FoundValue
 */
public class NotFoundValue extends EnvValue {
    boolean isNotFound() {
        return true;
    }
}