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19 package org.apache.cayenne.enhancer;
20
21 import org.objectweb.asm.ClassVisitor;
22 import org.objectweb.asm.FieldVisitor;
23 import org.objectweb.asm.Label;
24 import org.objectweb.asm.MethodVisitor;
25 import org.objectweb.asm.Opcodes;
26 import org.objectweb.asm.Type;
27
28
35 public class EnhancementHelper {
36
37
41 public static boolean isGeneratedField(String  name) {
42 return name != null && name.startsWith(fieldPrefix);
43 }
44
45 private static String fieldPrefix = "$cay_";
46 private ClassVisitor classVisitor;
47 private Type currentClass;
48
49 public EnhancementHelper(ClassVisitor classVisitor) {
50 this.classVisitor = classVisitor;
51 }
52
53 public Type getCurrentClass() {
54 return currentClass;
55 }
56
57 public String getPropertyField(String propertyName) {
58 return fieldPrefix + propertyName;
59 }
60
61 public void reset(String className) {
62 this.currentClass = Type.getType("L" + className + ";");
64 }
65
66 public String [] addInterface(String [] interfaces, Class newInterface) {
67
68 String name = Type.getInternalName(newInterface);
69 if (interfaces == null || interfaces.length == 0) {
70 return new String [] {
71 name
72 };
73 }
74
75 String [] expandedInterfaces = new String [interfaces.length + 1];
76 expandedInterfaces[0] = name;
77 System.arraycopy(interfaces, 0, expandedInterfaces, 1, interfaces.length);
78
79 return expandedInterfaces;
80 }
81
82
86 public void createField(Class fieldType, String name) {
87 createField(fieldType, name, false);
88 }
89
90
94 public void createField(Class fieldType, String name, boolean isTransient) {
95 Type asmType = Type.getType(fieldType);
96 int access = Opcodes.ACC_PROTECTED;
97 if (isTransient) {
98 access += Opcodes.ACC_TRANSIENT;
99 }
100
101 createField(name, asmType, access);
102 }
103
104 public void createProperty(Class propertyType, String name) {
105 createProperty(propertyType, name, false);
106 }
107
108 public void createProperty(Class propertyType, String name, boolean isTransient) {
109 Type asmType = Type.getType(propertyType);
110
111 int access = Opcodes.ACC_PROTECTED;
112 if (isTransient) {
113 access += Opcodes.ACC_TRANSIENT;
114 }
115
116 createField(name, asmType, access);
117 createGetter(name, asmType);
118 createSetter(name, asmType);
119 }
120
121 private void createSetter(String propertyName, Type asmType) {
122
123 String methodName = "set" + Character.toUpperCase(propertyName.charAt(0));
124 if (propertyName.length() > 1) {
125 methodName += propertyName.substring(1);
126 }
127
128 MethodVisitor mv = classVisitor.visitMethod(Opcodes.ACC_PUBLIC, methodName, "("
129 + asmType.getDescriptor()
130 + ")V", null, null);
131 mv.visitCode();
132 Label l0 = new Label();
133 mv.visitLabel(l0);
134 mv.visitVarInsn(Opcodes.ALOAD, 0);
135
136 if ("I".equals(asmType.getDescriptor())) {
138 mv.visitVarInsn(Opcodes.ILOAD, 1);
139 }
140 else {
141 mv.visitVarInsn(Opcodes.ALOAD, 1);
142 }
143
144 mv.visitFieldInsn(
145 Opcodes.PUTFIELD,
146 currentClass.getInternalName(),
147 getPropertyField(propertyName),
148 asmType.getDescriptor());
149 mv.visitInsn(Opcodes.RETURN);
150 Label l1 = new Label();
151 mv.visitLabel(l1);
152 mv.visitLocalVariable("this", currentClass.getDescriptor(), null, l0, l1, 0);
153 mv.visitLocalVariable(propertyName, asmType.getDescriptor(), null, l0, l1, 1);
154 mv.visitMaxs(2, 2);
155 mv.visitEnd();
156 }
157
158 private void createGetter(String propertyName, Type asmType) {
159
160 String prefix = "boolean".equals(asmType.getClassName()) ? "is" : "get";
161 String methodName = prefix + Character.toUpperCase(propertyName.charAt(0));
162 if (propertyName.length() > 1) {
163 methodName += propertyName.substring(1);
164 }
165
166 MethodVisitor mv = classVisitor.visitMethod(Opcodes.ACC_PUBLIC, methodName, "()"
167 + asmType.getDescriptor(), null, null);
168 mv.visitCode();
169 Label l0 = new Label();
170 mv.visitLabel(l0);
171 mv.visitVarInsn(Opcodes.ALOAD, 0);
172 mv.visitFieldInsn(
173 Opcodes.GETFIELD,
174 currentClass.getInternalName(),
175 getPropertyField(propertyName),
176 asmType.getDescriptor());
177
178 if ("I".equals(asmType.getDescriptor())) {
180 mv.visitInsn(Opcodes.IRETURN);
181 }
182 else {
183 mv.visitInsn(Opcodes.ARETURN);
184 }
185
186 Label l1 = new Label();
187 mv.visitLabel(l1);
188 mv.visitLocalVariable("this", currentClass.getDescriptor(), null, l0, l1, 0);
189 mv.visitMaxs(1, 1);
190 mv.visitEnd();
191 }
192
193 private void createField(String propertyName, Type asmType, int access) {
194 FieldVisitor fv = classVisitor.visitField(
195 access,
196 getPropertyField(propertyName),
197 asmType.getDescriptor(),
198 null,
199 null);
200 fv.visitEnd();
201 }
202 }
203 |
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