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package jdk.nashorn.api.tree;


Indicates that an unknown kind of Tree was encountered. This can occur if the language evolves and new kinds of Trees are added to the Tree hierarchy. May be thrown by a tree visitor to indicate that the visitor was created for a prior version of the language. 
Since:
9/**
 * Indicates that an unknown kind of Tree was encountered.  This
 * can occur if the language evolves and new kinds of Trees are
 * added to the {@code Tree} hierarchy.  May be thrown by a
 * {@linkplain TreeVisitor tree visitor} to indicate that the
 * visitor was created for a prior version of the language.
 *
 * @since 9
 */
public class UnknownTreeException extends RuntimeException {

    private static final long serialVersionUID = 1L;

    private transient final Tree tree;
    private transient final Object parameter;

    
Creates a new UnknownTreeException. The p parameter may be used to pass in an additional argument with information about the context in which the unknown element was encountered; for example, the visit methods of TreeVisitor may pass in their additional parameter. 
Params:
t – the unknown tree, may be null
p – an additional parameter, may be null/**
     * Creates a new {@code UnknownTreeException}.  The {@code p}
     * parameter may be used to pass in an additional argument with
     * information about the context in which the unknown element was
     * encountered; for example, the visit methods of {@link
     * TreeVisitor} may pass in their additional parameter.
     *
     * @param t the unknown tree, may be {@code null}
     * @param p an additional parameter, may be {@code null}
     */
    public UnknownTreeException(final Tree t, final Object p) {
        super("Unknown tree: " + t);
        this.tree = t;
        this.parameter = p;
    }

    
Returns the unknown tree.
The value may be unavailable if this exception has been
serialized and then read back in.
Returns:
the unknown element, or null if unavailable/**
     * Returns the unknown tree.
     * The value may be unavailable if this exception has been
     * serialized and then read back in.
     *
     * @return the unknown element, or {@code null} if unavailable
     */
    public Tree getUnknownTree() {
        return tree;
    }

    
Returns the additional argument.
The value may be unavailable if this exception has been
serialized and then read back in.
Returns:
the additional argument/**
     * Returns the additional argument.
     * The value may be unavailable if this exception has been
     * serialized and then read back in.
     *
     * @return the additional argument
     */
    public Object getArgument() {
        return parameter;
    }
}