/*
 * FindBugs - Find Bugs in Java programs
 * Copyright (C) 2003-2007 University of Maryland
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.ba.ch;

import edu.umd.cs.findbugs.ba.XClass;
import edu.umd.cs.findbugs.ba.XMethod;
import edu.umd.cs.findbugs.classfile.ClassDescriptor;

/**
 * This class implements a best-effort visitation
 * of all methods overridden by a given derived instance method.
 * Objects extending this class can be used with the
 * {@link Subtypes2#traverseSupertypes(ClassDescriptor, InheritanceGraphVisitor)}
 * method.
 * 
 * @author David Hovemeyer
 */
public abstract class OverriddenMethodsVisitor implements InheritanceGraphVisitor {
	private XMethod xmethod;

	/**
	 * Constructor. 
	 * 
	 * @param xmethod a derived method
	 */
	public OverriddenMethodsVisitor(XMethod xmethod) {
		assert !xmethod.isStatic();
		this.xmethod = xmethod;
	}

	/**
	 * @return Returns the xmethod.
	 */
	public XMethod getXmethod() {
		return xmethod;
	}

	/* (non-Javadoc)
	 * @see edu.umd.cs.findbugs.ba.ch.InheritanceGraphVisitor#visitClass(edu.umd.cs.findbugs.classfile.ClassDescriptor, edu.umd.cs.findbugs.ba.XClass)
	 */
	public boolean visitClass(ClassDescriptor classDescriptor, XClass xclass) {
		assert xclass != null;
		String methodSignature;
		boolean bridged = xmethod.isBridged();
		if (bridged && !classDescriptor.equals(xmethod.getClassDescriptor())) {
			methodSignature = xmethod.getBridgeSignature();
		} else {
			methodSignature = xmethod.getSignature();			
		}
		// See if this class has an overridden method
		XMethod xm = xclass.findMethod(xmethod.getName(), methodSignature, false);
		if (xm == null && bridged && xclass.isInterface()) {
			// if the method is bridged and the superclass is an interface, 
			// check the exact signature as well
			xm = xclass.findMethod(xmethod.getName(), xmethod.getSignature(), false);
		}

		if (xm != null) {
			return visitOverriddenMethod(xm) || bridged;
		} else {
			// Even though this particular class doesn't contain the method we're
			// looking for, a superclass might, so we need to keep going.
			return true;
		}
	}

	/* (non-Javadoc)
	 * @see edu.umd.cs.findbugs.ba.ch.InheritanceGraphVisitor#visitEdge(edu.umd.cs.findbugs.classfile.ClassDescriptor, edu.umd.cs.findbugs.ba.XClass, edu.umd.cs.findbugs.classfile.ClassDescriptor, edu.umd.cs.findbugs.ba.XClass)
	 */
	public boolean visitEdge(ClassDescriptor sourceDesc, XClass source, ClassDescriptor targetDesc, XClass target) {
		return (target != null);
	}

	/**
	 * Downcall method: will be called for each method overridden by
	 * the derived method object passed to the constructor.
	 * Note that this method will be called <em>for</em> the original
	 * derived method, since this is useful for some applications.
	 * 
	 * @param xmethod a method which is overridden by the
	 *                original derived method, or is the original derived method 
	 * @return true if the traversal should continue into superclasses, false otherwise
	 */
	protected abstract boolean visitOverriddenMethod(XMethod xmethod);
}