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1   /*
2    * $Id: NewInstanceMetaMethod.java,v 1.1 2004/03/25 00:35:19 glaforge Exp $
3    *
4    * Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.
5    *
6    * Redistribution and use of this software and associated documentation
7    * ("Software"), with or without modification, are permitted provided that the
8    * following conditions are met:
9    *  1. Redistributions of source code must retain copyright statements and
10   * notices. Redistributions must also contain a copy of this document.
11   *  2. Redistributions in binary form must reproduce the above copyright
12   * notice, this list of conditions and the following disclaimer in the
13   * documentation and/or other materials provided with the distribution.
14   *  3. The name "groovy" must not be used to endorse or promote products
15   * derived from this Software without prior written permission of The Codehaus.
16   * For written permission, please contact info@codehaus.org.
17   *  4. Products derived from this Software may not be called "groovy" nor may
18   * "groovy" appear in their names without prior written permission of The
19   * Codehaus. "groovy" is a registered trademark of The Codehaus.
20   *  5. Due credit should be given to The Codehaus - http://groovy.codehaus.org/
21   *
22   * THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS ``AS IS'' AND ANY
23   * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
24   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
25   * DISCLAIMED. IN NO EVENT SHALL THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR
26   * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
28   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
29   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
32   * DAMAGE.
33   *
34   */
35  package org.codehaus.groovy.runtime;
36  
37  import groovy.lang.MetaMethod;
38  
39  import java.lang.reflect.Modifier;
40  
41  /***
42   * A MetaMethod implementation where the underlying method is really a static
43   * helper method on some class but it appears to be an instance method on a class.
44   * 
45   * This implementation is used to add new methods to the JDK writing them as normal
46   * static methods with the first parameter being the class on which the method is added.
47   * 
48   * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
49   * @version $Revision: 1.1 $
50   */
51  public class NewInstanceMetaMethod extends MetaMethod {
52  
53      private static final Class[] EMPTY_TYPE_ARRAY = {};
54      
55      private MetaMethod metaMethod;
56      private Class[] logicalParameterTypes;
57  
58      public NewInstanceMetaMethod(MetaMethod metaMethod) {
59          super(metaMethod);
60          this.metaMethod = metaMethod;
61          Class[] realParameterTypes = metaMethod.getParameterTypes();
62          int size = realParameterTypes.length;
63          if (size <= 1) {
64              logicalParameterTypes = EMPTY_TYPE_ARRAY;
65          }
66          else {
67              logicalParameterTypes = new Class[--size];
68              System.arraycopy(realParameterTypes, 1, logicalParameterTypes, 0, size);
69          }
70      }
71  
72      public Class getDeclaringClass() {
73          return getBytecodeParameterTypes()[0];
74      }
75  
76      public boolean isStatic() {
77          return false;
78      }
79  
80      public int getModifiers() {
81          // lets clear the static bit
82          return super.getModifiers() ^ Modifier.STATIC;
83      }
84  
85      public Class[] getParameterTypes() {
86          return logicalParameterTypes;
87      }
88  
89      public Class[] getBytecodeParameterTypes() {
90          return super.getParameterTypes();
91      }
92  
93      public Object invoke(Object object, Object[] arguments) throws Exception {
94          // we need to cheat using the type
95          int size = arguments.length;
96          Object[] newArguments = new Object[size + 1];
97          newArguments[0] = object;
98          System.arraycopy(arguments, 0, newArguments, 1, size);
99          return metaMethod.invoke(null, newArguments);
100     }
101 }