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  package org.apache.cayenne.exp.parser;
  
  import java.io.IOException;
  import java.util.List;
  
  import org.apache.cayenne.exp.Expression;
  
  /**
   * Boolean false expression element
   * 
   * Notice that there is one ASTTrue and one ASTFalse instead of a ASTBoolean
   * with a Boolean value. The main reason for doing this is that a common
   * ASTBoolean will have operand count of 1 and that will default to a prepared
   * statement like " where ? and (...)", but we only need " where true and
   * (...)".
   * 
   * @see ASTTrue
   * @since 3.0
   */
  public class ASTFalse extends ConditionNode {
  
  	private static final long serialVersionUID = -8441997825701749863L;
  
  	/**
  	 * Constructor used by expression parser. Do not invoke directly.
  	 */
  	ASTFalse(int id) {
  		super(id);
  	}
  
  	public ASTFalse() {
  		super(ExpressionParserTreeConstants.JJTFALSE);
  	}
  
  	@Override
  	protected int getRequiredChildrenCount() {
  		return 0;
  	}
  
  	@Override
  	protected Boolean evaluateSubNode(Object o, Object[] evaluatedChildren) throws Exception {
  		return Boolean.FALSE;
  	}
  
  	@Override
  	protected String getExpressionOperator(int index) {
  		throw new UnsupportedOperationException("No operator for '" + ExpressionParserTreeConstants.jjtNodeName[id] + "'");
  	}
  
  	@Override
  	public Expression shallowCopy() {
  		return new ASTFalse(id);
  	}
  
  	@Override
  	public int getType() {
  		return Expression.FALSE;
  	}
  
  	/**
  	 * @since 4.0
  	 */
  	@Override
  	public void appendAsString(Appendable out) throws IOException {
  		out.append("false");
  	}
  
  	/**
  	 * @since 4.0
  	 */
  	@Override
  	public void appendAsEJBQL(List<Object> parameterAccumulator, Appendable out, String rootId) throws IOException {
  		out.append("false");
  	}
  }
  