/* java.lang.reflect.VMMethod - VM interface for reflection of Java methods
   Copyright (C) 1998, 2001, 2002, 2005, 2007, 2008 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the 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, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


package java.lang.reflect;

import java.lang.annotation.Annotation;

import java.util.Arrays;
import java.util.Map;

final class VMMethod
{
  Class clazz;
  String name;
  int slot;

  /**
   * Unparsed annotations.
   */
  private byte[] annotations          = null;

  /**
   * Unparsed parameter annotations.
   */
  private byte[] parameterAnnotations = null;
  
  /**
   * Unparsed annotation default value.
   */
  private byte[] annotationDefault    = null;

  /**
   * Annotations get parsed the first time they are
   * accessed and are then cached it this map.
   */
  private transient Map<Class<? extends Annotation>, Annotation> declaredAnnotations = null;

  /**
   * Helper array for creating a new array from a java.util.Container.
   */
  private static final Annotation[] EMPTY_ANNOTATIONS_ARRAY =
    new Annotation[0];

  /** 
   * This field allows us to refer back to the main constructor instance.
   *  It is set by the constructor of Field.
   */
  Method m;

  public Class getDeclaringClass()
  {
    return clazz;
  }

  public String getName()
  {
    return name;
  }

  /**
   * Return the raw modifiers for this method.
   * @return the method's modifiers
   */
  native int getModifiersInternal();

  /**
   * Gets the return type of this method.
   * @return the type of this method
   */
  native Class getReturnType();

  /**
   * Get the parameter list for this method, in declaration order. If the
   * method takes no parameters, returns a 0-length array (not null).
   *
   * @return a list of the types of the method's parameters
   */
  native Class[] getParameterTypes();

  /**
   * Get the exception types this method says it throws, in no particular
   * order. If the method has no throws clause, returns a 0-length array
   * (not null).
   *
   * @return a list of the types in the method's throws clause
   */
  native Class[] getExceptionTypes();

  native Object invoke(Object o, Object[] args)
    throws IllegalAccessException, InvocationTargetException;

  /**
   * Return the String in the Signature attribute for this method. If there
   * is no Signature attribute, return null.
   */
  native String getSignature();

  /**
   * If this method is an annotation method, returns the default
   * value for the method.  If there is no default value, or if the
   * method is not a member of an annotation type, returns null.
   * Primitive types are wrapped.
   *
   * @throws TypeNotPresentException if the method returns a Class,
   * and the class cannot be found
   *
   * @since 1.5
   */
  native Object getDefaultValue();

  /**
   * <p>
   * Return an array of arrays representing the annotations on each
   * of the method's parameters.  The outer array is aligned against
   * the parameters of the method and is thus equal in length to
   * the number of parameters (thus having a length zero if there are none).
   * Each array element in the outer array contains an inner array which
   * holds the annotations.  This array has a length of zero if the parameter
   * has no annotations.
   * </p>
   * <p>
   * The returned annotations are serialized.  Changing the annotations has
   * no affect on the return value of future calls to this method.
   * </p>
   * 
   * @return an array of arrays which represents the annotations used on the
   *         parameters of this method.  The order of the array elements
   *         matches the declaration order of the parameters.
   * @since 1.5
   */
  native Annotation[][] getParameterAnnotations();

  /**
   * Compare two objects to see if they are semantically equivalent.
   * Two Methods are semantically equivalent if they have the same declaring
   * class, name, parameter list, and return type.
   *
   * @param o the object to compare to
   * @return <code>true</code> if they are equal; <code>false</code> if not
   */
  public boolean equals(Object o)
  {
      // Implementation note:
      // The following is a correct but possibly slow implementation.
      //
      // This class has a private field 'slot' that could be used by
      // the VM implementation to "link" a particular method to a Class.
      // In that case equals could be simply implemented as:
      //
      // if (o instanceof Method)
      // {
      //    Method m = (Method)o;
      //    return m.declaringClass == this.declaringClass
      //           && m.slot == this.slot;
      // }
      // return false;
      //
      // If a VM uses the Method class as their native/internal representation
      // then just using the following would be optimal:
      //
      // return this == o;
      //
    if (!(o instanceof Method))
      return false;
    Method that = (Method)o;
    if (clazz != that.getDeclaringClass())
      return false;
    if (!name.equals(that.getName()))
      return false;
    if (getReturnType() != that.getReturnType())
      return false;
    if (!Arrays.equals(getParameterTypes(), that.getParameterTypes()))
      return false;
    return true;
  }

  /**
   * Returns the element's annotation for the specified annotation type,
   * or <code>null</code> if no such annotation exists.
   *
   * @param annotationClass the type of annotation to look for.
   * @return this element's annotation for the specified type, or
   *         <code>null</code> if no such annotation exists.
   * @throws NullPointerException if the annotation class is <code>null</code>.
   */
//   native Annotation getAnnotation(Class annotationClass);
  Annotation getAnnotation(Class annotationClass) {
    if (annotationClass == null)
      throw new NullPointerException();

    return declaredAnnotations().get(annotationClass);
  }

  /**
   * Returns all annotations directly defined by the element.  If there are
   * no annotations directly associated with the element, then a zero-length
   * array will be returned.  The returned array may be modified by the client
   * code, but this will have no effect on the annotation content of this
   * class, and hence no effect on the return value of this method for
   * future callers.
   *
   * @return the annotations directly defined by the element.
   * @since 1.5
   */
//   native Annotation[] getDeclaredAnnotations();
  Annotation[] getDeclaredAnnotations() {
    return declaredAnnotations().values().toArray(EMPTY_ANNOTATIONS_ARRAY);
  }

  /**
   * Parses the annotations if they aren't parsed yet and stores them into
   * the declaredAnnotations map and return this map.
   */
  private synchronized native Map<Class<? extends Annotation>, Annotation> declaredAnnotations();

}

