001/**
002 * ScalarGuard.java
003 * 
004 * Copyright (c) 2004-2012, Nicole C. Tedesco. All rights reserved.
005 * 
006 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
007 * use this file except in compliance with the License. You may obtain a copy of
008 * the License at:
009 * 
010 * http://www.apache.org/licenses/LICENSE-2.0
011 * 
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
014 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
015 * License for the specific language governing permissions and limitations under
016 * the License.
017 */
018
019package net.sf.jaccumulator.lex;
020
021/**
022 * Determines whether a {@link NullAction null} signal should be rejected or
023 * accepted within the current context of a specific model
024 * 
025 * @param <MODEL>
026 *        the model type to test against
027 * 
028 * @since JAccumulator 4.0
029 * @author Nicole Tedesco (<a
030 *         href="mailto:nicole@tedesco.name">nicole@tedesco.name</a>)
031 */
032public interface NullGuard<MODEL>
033    extends
034        Guard<MODEL>
035{
036    public boolean acceptNull( final MODEL aModel );
037
038    public NullGuard<MODEL> getNullGuardAt( final int anIndex )
039        throws IndexOutOfBoundsException;
040
041    public int getNullGuardChildCount();
042}