AbstractClause.java

package dods.dap.Server;

import java.util.*;

/** Provides default implementations for the Clause interface methods. 
 *  This eliminates redundant code and provides a starting point 
 *  for new implementations of Clause. <p>
 * 
 *  Note that every Clause object is expected to implement either 
 *  SubClause or TopLevelClause. No default implementations are provided
 *  for the methods of these subinterfaces <p>
 * 
 *  Also note that it is not <i>necessary</i> to use this class to 
 *  create your own implementations, it's just a convenience.<p>
 *  
 *  The class has no abstract methods, but is declared abstract because
 *  it should not be directly instantiated.
 *
 * @author joew */
public abstract class AbstractClause 
    implements Clause {

    public List getChildren() {
	return children;
    }

    public boolean isConstant() {
	return constant;
    }
    
    public boolean isDefined() {
	return defined;
    }

    /** Value to be returned by isConstant(). Should not change for
     *  the lifetime of the object. */
    protected boolean constant;

    /** Value to be returned by isDefined(). May change during the
     *  lifetime of the object. */
    protected boolean defined;

    /** A list of SubClause objects representing 
     *  the sub-clauses of this clause. Use caution when modifying
     *  this list other than at the point of creation, since methods
     *  such as evaluate() depend on it. */
    protected List children;
}