/* VMStackWalker.java -- Reference implementation of VM hooks for stack access   Copyright (C) 2005 Free Software FoundationThis file is part of GNU Classpath.GNU Classpath is free software; you can redistribute it and/or modifyit under the terms of the GNU General Public License as published bythe Free Software Foundation; either version 2, or (at your option)any later version.GNU Classpath is distributed in the hope that it will be useful, butWITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNUGeneral Public License for more details.You should have received a copy of the GNU General Public Licensealong with GNU Classpath; see the file COPYING.  If not, write to theFree Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307 USA.Linking this library statically or dynamically with other modules ismaking a combined work based on this library.  Thus, the terms andconditions of the GNU General Public License cover the wholecombination.As a special exception, the copyright holders of this library give youpermission to link this library with independent modules to produce anexecutable, regardless of the license terms of these independentmodules, and to copy and distribute the resulting executable underterms of your choice, provided that you also meet, for each linkedindependent module, the terms and conditions of the license of thatmodule.  An independent module is a module which is not derived fromor based on this library.  If you modify this library, you may extendthis exception to your version of the library, but you are notobligated to do so.  If you do not wish to do so, delete thisexception statement from your version. */package gnu.classpath;/** * This class provides access to the classes on the Java stack * for reflection and security purposes. * <p> * This class is only available to priviledged code (i.e., code loaded * by the bootstrap loader). * <p> * VM runtime implementers only need to implement the native getClassContext() * method. But are encouraged to implement the other methods more efficiently * when possible. * * @author John Keiser * @author Eric Blake <ebb9@email.byu.edu> * @author Archie Cobbs */public final class VMStackWalker{  /**   * Get a list of all the classes currently executing methods on the   * Java stack. <code>getClassContext()[0]</code> is the class associated   * with the currently executing method, i.e., the method that called   * <code>VMStackWalker.getClassContext()</code> (possibly through   * reflection). So you may need to pop off these stack frames from   * the top of the stack:   * <ul>   * <li><code>VMStackWalker.getClassContext()</code>   * <li><code>Method.invoke()</code>   * </ul>   *   * @return an array of the declaring classes of each stack frame   */  public static native Class[] getClassContext();  /**   * Get the class associated with the method invoking the method   * invoking this method, or <code>null</code> if the stack is not   * that deep (e.g., invoked via JNI invocation API). This method   * is an optimization for the expression <code>getClassContext(c)[0]</code>   * and should return the same result.   *   * <p>   * VM implementers are encouraged to provide a more efficient   * version of this method.   */  public static native Class getCallingClass();  /**   * Get the class loader associated with the Class returned by   * <code>getCallingClass()</code>, or <code>null</code> if no   * such class exists or it is the boot loader. This method is an optimization   * for the expression <code>getCallingClass().getClassLoader()</code>   * and should return the same result.   *   * <p>   * VM implementers are encouraged to provide a more efficient   * version of this method.   */  public static native ClassLoader getCallingClassLoader();}