TopLinkClassWeaver


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4    * (the "License").  You may not use this file except 
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6    * 
7    * You can obtain a copy of the license at 
8    * glassfish/bootstrap/legal/CDDLv1.0.txt or 
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21  // Copyright (c) 2005, 2006, Oracle. All rights reserved.  
22  package oracle.toplink.essentials.internal.weaving;
23  
24  //J2SE imports
25  import java.util.*;
26  
27  //ASM imports
28  import oracle.toplink.libraries.asm.*;
29  import oracle.toplink.libraries.asm.attrs.RuntimeVisibleAnnotations;
30  import oracle.toplink.libraries.asm.attrs.Annotation;
31  
32  /**
33   * INTERNAL:
34   * Weaves classes to allow them to support TopLink indirection.
35   * Classes are weaved to add a variable of type ValueHolderInterface for each attribute
36   * that uses indirection.  In addition, access methods are added for the new variable.
37   * Also, triggers the process of weaving the methods of the class.  
38   * @see oracle.toplink.essentials.internal.weaving.TopLinkMethodWeaver
39   */
40  
41  public class TopLinkClassWeaver extends ClassAdapter implements Constants {
42  
43      public static final String   VHI_CLASSNAME =
44          "oracle.toplink.essentials.indirection.ValueHolderInterface";
45      public static final String   VH_SHORT_SIGNATURE =
46          "oracle/toplink/essentials/indirection/ValueHolder";
47      public static final String   VHI_SHORT_SIGNATURE =
48          "oracle/toplink/essentials/indirection/ValueHolderInterface";
49      public static final String   VHI_SIGNATURE =
50          "L" + VHI_SHORT_SIGNATURE +";";
51      public static final String   TW_SHORT_SIGNATURE =
52          "oracle/toplink/essentials/internal/weaving/TopLinkWeaved";
53      
54      protected ClassDetails classDetails;
55      public boolean alreadyWeaved = false;
56      public boolean weavedVH = false;
57  
58      public TopLinkClassWeaver(ClassWriter classWriter, ClassDetails classDetails) {
59          super(classWriter);
60          this.classDetails = classDetails;
61      }
62  
63      /**
64      *  INTERNAL:
65      *  Add a variable of type ValueHolderInterface to the class.  When this method has been run, the
66      *  class will contain a variable declaration similar to the following:
67      *  
68      *  private ValueHolderInterface _toplink_variableName_vh;
69      */
70      public void addValueHolder(AttributeDetails attributeDetails){
71          String   attribute = attributeDetails.getAttributeName();
72          RuntimeVisibleAnnotations annotations = null;
73          if (attributeDetails.getMapping().getGetMethodName() == null || attributeDetails.getMapping().getGetMethodName().equals("")){
74              annotations = getTransientAnnotation();
75          }
76          weavedVH = true;  
77          cv.visitField(ACC_PRIVATE, "_toplink_" + attribute + "_vh", "Loracle/toplink/essentials/indirection/ValueHolderInterface;", null, annotations);
78      }
79  
80      /**
81       * INTERNAL:
82       * Add a get method for the newly added valueholder.  Adds a method of the followign form:
83       * 
84       *     public ValueHolderInterface _toplink_getvariableName_vh(){
85       *         return _toplink_variableName_vh;
86       *     }
87       */
88      public void addGetterMethodForValueHolder(ClassDetails classDetails, AttributeDetails attributeDetails){
89          String   attribute = attributeDetails.getAttributeName();
90          String   className = classDetails.getClassName();
91          // Create a getter method for the new valueholder
92          CodeVisitor cv_get_VH = cv.visitMethod(ACC_PUBLIC, "_toplink_get" + attribute + "_vh", "()" + VHI_SIGNATURE, null, null);
93          cv_get_VH.visitVarInsn(ALOAD, 0);
94          cv_get_VH.visitFieldInsn(GETFIELD, className, "_toplink_" + attribute + "_vh", "Loracle/toplink/essentials/indirection/ValueHolderInterface;");
95          cv_get_VH.visitInsn(ARETURN);
96          cv_get_VH.visitMaxs(0, 0);
97      }
98      
99      /**
100      * INTERNAL:
101      * Add a set method for the newly added ValueHolder.  Adds a method of this form:
102      * 
103      *     public void  _toplink_setvariableName_vh(ValueHolderInterface valueholderinterface)
104      *         _toplink_variableName_vh = valueholderinterface;
105      *     }
106      */
107     public void addSetterMethodForValueHolder(ClassDetails classDetails, AttributeDetails attributeDetails){
108         String   attribute = attributeDetails.getAttributeName();
109         String   className = classDetails.getClassName();
110         // create a setter method for the new valueholder
111         CodeVisitor cv_set_value = cv.visitMethod(ACC_PUBLIC, "_toplink_set" + attribute + "_vh", "(Loracle/toplink/essentials/indirection/ValueHolderInterface;)V", null, null);                     
112         cv_set_value.visitVarInsn(ALOAD, 0);
113         cv_set_value.visitVarInsn(ALOAD, 1);
114         cv_set_value.visitFieldInsn(PUTFIELD, className, "_toplink_" + attribute + "_vh", "Loracle/toplink/essentials/indirection/ValueHolderInterface;");
115         cv_set_value.visitInsn(RETURN);
116         cv_set_value.visitMaxs(0, 0);
117     }
118     
119     /**
120      * INTERNAL:
121      * Adds a convenience method used to replace a PUTFIELD when field access is used. The method follows
122      * the following form:
123      *     
124      *     public void _toplink_setvariableName(<VariableClas> item) {
125      *          _toplink_variableName_vh.setValue(item);
126      *          this.item = item;
127      *      }
128      * 
129      */
130     public void addSetterMethodForFieldAccess(ClassDetails classDetails, AttributeDetails attributeDetails){
131         String   attribute = attributeDetails.getAttributeName();
132         CodeVisitor cv_set = cv.visitMethod(ACC_PUBLIC, "_toplink_set" + attribute, "(L" + attributeDetails.getReferenceClass().replace('.','/') + ";)V", null, null);
133         cv_set.visitVarInsn(ALOAD, 0);
134         cv_set.visitFieldInsn(GETFIELD, classDetails.getClassName(), "_toplink_" + attribute + "_vh", TopLinkClassWeaver.VHI_SIGNATURE);
135         cv_set.visitVarInsn(ALOAD, 1);
136         cv_set.visitMethodInsn(INVOKEINTERFACE, TopLinkClassWeaver.VHI_SHORT_SIGNATURE, "setValue", "(Ljava/lang/Object;)V");
137         cv_set.visitVarInsn(ALOAD, 0);
138         cv_set.visitVarInsn(ALOAD, 1);
139         cv_set.visitFieldInsn(PUTFIELD, classDetails.getClassName(), attribute, "L" + attributeDetails.getReferenceClass().replace('.','/') + ";");
140         cv_set.visitInsn(RETURN);
141         cv_set.visitMaxs(0 ,0);
142     }
143 
144     /**
145      * INTERNAL:
146      * Adds a convenience method used to replace a GETFIELD when field access is used. The method follows
147      * the following form:
148      * 
149      *      public <VariableClass> _toplink_getvariableName(){
150      *          this.item = (<VariableClass>)_toplink_variableName_vh.getValue();
151      *          return this.item;
152      *      }
153      * 
154      */
155     public void addGetterMethodForFieldAccess(ClassDetails classDetails, AttributeDetails attributeDetails){
156         String   attribute = attributeDetails.getAttributeName();
157 
158         CodeVisitor cv_get = cv.visitMethod(ACC_PUBLIC, "_toplink_get" + attribute, "()L" + attributeDetails.getReferenceClass().replace('.','/') + ";", null, null);
159         cv_get.visitVarInsn(ALOAD, 0);
160         cv_get.visitVarInsn(ALOAD, 0);
161         cv_get.visitFieldInsn(GETFIELD, classDetails.getClassName(), "_toplink_" + attribute + "_vh", TopLinkClassWeaver.VHI_SIGNATURE);
162         cv_get.visitMethodInsn(INVOKEINTERFACE, TopLinkClassWeaver.VHI_SHORT_SIGNATURE, "getValue", "()Ljava/lang/Object;");
163         cv_get.visitTypeInsn(CHECKCAST, attributeDetails.getReferenceClass().replace('.','/'));
164         cv_get.visitFieldInsn(PUTFIELD, classDetails.getClassName(), attribute, "L" + attributeDetails.getReferenceClass().replace('.','/') + ";");
165         cv_get.visitVarInsn(ALOAD, 0);
166         cv_get.visitFieldInsn(GETFIELD, classDetails.getClassName(), attribute, "L" + attributeDetails.getReferenceClass().replace('.','/') + ";");
167         cv_get.visitInsn(ARETURN);
168         cv_get.visitMaxs(0, 0);
169     }
170    
171     private RuntimeVisibleAnnotations getTransientAnnotation(){
172         RuntimeVisibleAnnotations attrs = new RuntimeVisibleAnnotations();
173         Annotation transientAnnotation = new Annotation("Ljavax/persistence/Transient;");
174         attrs.annotations.add(transientAnnotation);
175         return attrs;
176     }
177     
178     // add ChangeTracker, TopLinkWeaved interfaces
179     public void visit(int version, int access, String   name, String   superName,
180         String  [] interfaces, String   sourceFile) {
181 
182         // prevent 'double' weaving: scan for TopLinkWeaved interface
183         for (int i = 0; i < interfaces.length; i++) {
184             String   s = interfaces[i];
185             if (TW_SHORT_SIGNATURE.equals(s)) {
186                 alreadyWeaved = true;
187                 break;
188             }
189         }
190         
191         if (!alreadyWeaved) {
192             int len = 1 + interfaces.length;
193             String  [] newInterfaces = new String  [len];
194             System.arraycopy(interfaces, 0, newInterfaces, 0, interfaces.length);
195             // add 'marker' oracle.toplink.essentials.internal.weaving.TopLinkWeaved interface
196             newInterfaces[interfaces.length] = TW_SHORT_SIGNATURE;
197             super.visit(version, access, name, superName, newInterfaces,
198                 sourceFile);
199         } else {
200             super.visit(version, access, name, superName, interfaces, sourceFile);
201         }
202 
203     }
204 
205     /**
206      *  INTERNAL:
207      *  Construct a TopLinkMethodWeaver and allow it to process the method.
208      */
209     public CodeVisitor visitMethod(int access, String   methodName, String   desc,
210             String  [] exceptions, Attribute attrs) {
211 
212         if (!alreadyWeaved) {
213             return new TopLinkMethodWeaver(this, methodName, desc, cv.visitMethod(access, methodName, desc, exceptions, attrs));
214         } else {
215             return super.visitMethod(access, methodName, desc, exceptions, attrs);
216         }
217     }
218 
219     public void visitAttribute(Attribute attr) {
220         if (!alreadyWeaved) {
221             cv.visitAttribute(attr);
222         } else {
223             super.visitAttribute(attr);
224         }
225     }
226 
227     public void visitEnd() {
228         if (!alreadyWeaved) {
229             // add implementation of weavedValueHolders() method in the TopLinkWeaved interface
230             // this method will return true if we have weaved and false otherwise.
231             CodeVisitor cv_weavedValueHolders = cv.visitMethod(ACC_PUBLIC,
232                 "weavedValueHolders", "()Z", null, null);
233             if (classDetails.weavedValueHolders()) {
234                 cv_weavedValueHolders.visitInsn(ICONST_1);
235             } else {
236                 cv_weavedValueHolders.visitInsn(ICONST_0);
237             }
238             cv_weavedValueHolders.visitInsn(IRETURN);
239             cv_weavedValueHolders.visitMaxs(0, 0);
240         }
241         
242         // for each attribute we need to check what methods and variables to add
243         for (Iterator i = classDetails.getAttributesMap().values().iterator();i.hasNext();) {
244             AttributeDetails attributeDetails = (AttributeDetails)i.next();
245             if (attributeDetails.weaveValueHolders()) {
246                 
247                 // we will add valueholders and methods to classes that have not already been weaved
248                 // and classes that actually contain the attribute we are processing
249                 // an attribute could be in the classDetails but not actually in the class
250                 // if it is owned by a MappedSuperClass
251                 if (!alreadyWeaved && !attributeDetails.isAttributeOnSuperClass()){
252                     addValueHolder(attributeDetails);
253                     addGetterMethodForValueHolder(classDetails, attributeDetails);
254                     addSetterMethodForValueHolder(classDetails, attributeDetails);
255                     
256                     // We only add the following convenience method if we are using attribute access.
257                     if (attributeDetails.getMapping().usesIndirection() && attributeDetails.isMappedWithAttributeAccess()){
258                         addSetterMethodForFieldAccess(classDetails, attributeDetails);
259                         addGetterMethodForFieldAccess(classDetails, attributeDetails);
260                     }
261                 }
262  
263             }
264         }
265         super.visitEnd();
266     }
267 }
268
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