/*
 * @(#)InstanceOfQueryExp.java	1.4 05/11/30
 * 
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.management;


/**
 * This class is used by the query building mechanism for isInstanceOf expressions.
 * @serial include
 *
 * @since 1.6
 */
class InstanceOfQueryExp extends QueryEval implements QueryExp { 
    
    /* Serial version */
    private static final long serialVersionUID = -1081892073854801359L;

    /** 
     * @serial The {@link StringValueExp} returning the name of the class 
     *         of which selected MBeans should be instances.
     */
    private StringValueExp classNameValue;
    
    /**
     * Creates a new InstanceOfExp with a specific class name.
     * @param classNameValue The {@link StringValueExp} returning the name of 
     *        the class of which selected MBeans should be instances.
     */
    // We are using StringValueExp here to be consistent with other queries,
    // although we should actually either use a simple string (the classname)
    // or a ValueExp - which would allow more complex queries - like for 
    // instance evaluating the class name from an AttributeValueExp.
    // As it stands - using StringValueExp instead of a simple constant string
    // doesn't serve any useful purpose besides offering a consistent 
    // look & feel.
    public InstanceOfQueryExp(StringValueExp classNameValue) {
	if (classNameValue == null) {
	    throw new IllegalArgumentException("Null class name.");
	}
	
	this.classNameValue = classNameValue;
    } 
    
    /**
     * Returns the class name.
     * @returns The {@link StringValueExp} returning the name of 
     *        the class of which selected MBeans should be instances.
     */
    public StringValueExp getClassNameValue()  { 
	return classNameValue;
    } 
    
    /**
     * Applies the InstanceOf on a MBean.
     *
     * @param name The name of the MBean on which the InstanceOf will be applied.
     *
     * @return  True if the MBean specified by the name is instance of the class.
     * @exception BadAttributeValueExpException
     * @exception InvalidApplicationException
     * @exception BadStringOperationException
     * @exception BadBinaryOpValueExpException
     */
    public boolean apply(ObjectName name)
	throws BadStringOperationException,
	BadBinaryOpValueExpException,
	BadAttributeValueExpException,
	InvalidApplicationException {
        
        // Get the class name value 
        final StringValueExp val;
	try {
            val = (StringValueExp) classNameValue.apply(name);
	} catch (ClassCastException x) {
            // Should not happen - unless someone wrongly implemented
            // StringValueExp.apply().
            final BadStringOperationException y = 
                    new BadStringOperationException(x.toString());
            y.initCause(x);
            throw y;
	} 
        
        // Test whether the MBean is an instance of that class.
	try {            
	    return getMBeanServer().isInstanceOf(name, val.getValue());
	} catch (InstanceNotFoundException infe) {
	    return false;
        }
    }
    
    /**
     * Returns a string representation of this InstanceOfQueryExp.
     * @return a string representation of this InstanceOfQueryExp.
     */
    public String toString() {
       return "InstanceOf " + classNameValue.toString();
   }
}