/**
    * Copyright 2011-2013 The Kuali Foundation Licensed under the
    * Educational Community License, Version 2.0 (the "License"); you may
    * not use this file except in compliance with the License. You may
    * obtain a copy of the License at
    *
    * http://www.osedu.org/licenses/ECL-2.0
    *
    * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an "AS IS"
   * BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
   * or implied. See the License for the specific language governing
   * permissions and limitations under the License.
   */
  
  package org.kuali.mobility.security.authz.expression;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.kuali.mobility.security.user.api.User;
  
  public class NotExpression implements NonLeafExpression {
  
  	private static final long serialVersionUID = -777343514543759642L;
  
  	private List<Expression> children;
  
  	public NotExpression() {
  		children = new ArrayList<Expression>();
  	}
  
  	public boolean evaluate(User user) {
  		for (Expression child : children) {
  			if (child.evaluate(user)) {
  				return false;
  			}
  		}
  		return true;
  	}
  
  	public void addChild(Expression expression) {
  		children.add(expression);
  	}
  	
  	private Object readResolve() {
  		if (children == null) {
  			children = new ArrayList<Expression>();
  		}
  		return this;
  	}
  	
  	@Override
  	public boolean equals(Object obj) {
  		if (obj instanceof NotExpression) {
  			NotExpression other = (NotExpression)obj;
  			return children.equals(other.children);
  		}
  		return false;
  	}
  
  	@Override
  	public List<Expression> getChildren() {
  		return children;
  	}
  	
  }