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1
33 package net.sf.jga.fn.property;
34
35 import java.lang.reflect.InvocationTargetException  ;
36 import java.lang.reflect.Field ;
37 import java.text.MessageFormat ;
38 import net.sf.jga.fn.BinaryFunctor;
39 import net.sf.jga.fn.EvaluationException;
40
41
54
55
59 public class SetField<T,R> extends BinaryFunctor<T,R,R> {
60
61 static final long serialVersionUID = -5051261348109487737L;
62
63 private Class <R> _fieldType;
65
66 private String _fieldName;
68
69 private transient Field _field;
71
72
77 public SetField(Field field) {
78 this((Class <T>) field.getDeclaringClass(), field, (Class <R>) field.getType());
79 }
80
81
82
87 public SetField(Class <T> argType, Field field) {
88 this(argType, field, (Class <R>)field.getType());
89 }
90
91
92
97 public SetField(Class <T> argType, Field field, Class <R> fieldType) {
98 if (field == null) {
99 throw new IllegalArgumentException ("Must supply field");
100 }
101
102 if (!field.getDeclaringClass().isAssignableFrom(argType)) {
103 throw new IllegalArgumentException (buildNoSuchFieldMessage(field.getName(), argType));
104 }
105
106 _fieldName = field.getName();
107 _fieldType = fieldType;
108 _field = checkFieldType(field, fieldType);
109 }
110
111
112
118 public SetField(Class <T> argType, String fieldName, Class <R> fieldType) {
119 if (fieldName == null || fieldName.length() == 0) {
120 throw new IllegalArgumentException ("Must supply field name");
121 }
122 if (fieldType == null) {
123 throw new IllegalArgumentException ("Must supply field type");
124 }
125
126 _fieldName = fieldName;
127 _fieldType = fieldType;
128
129 try {
130 _field = checkFieldType(argType.getField(_fieldName), fieldType);
131 }
132 catch (NoSuchFieldException x) {
133 IllegalArgumentException iax =
134 new IllegalArgumentException (buildNoSuchFieldMessage(fieldName, argType));
135 iax.initCause(x);
136 throw iax;
137 }
138 }
139
140
141 private Field checkFieldType(Field field, Class <R> fieldType) throws IllegalArgumentException {
142 if (!field.getType().isAssignableFrom(fieldType)) {
143 String msg = "Field {0} is of the wrong type: is {1}, expected {2}";
144 Object [] args = new Object [] { field.getName(), field.getType().getName(),
145 fieldType.getName() };
146 throw new IllegalArgumentException (MessageFormat.format(msg, args));
147 }
148
149 return field;
150 }
151
152
153
156 public String getFieldName() {
157 return _fieldName;
158 }
159
160
162
170 public R fn(T arg, R val) {
171 try {
172 getField(arg).set(arg, val);
173 return null;
174 }
175 catch (ClassCastException x) {
176 String msg = "{0}.{1} is of type {2}";
177 Field f = getField(arg);
178 Object [] args = new Object []{ arg.getClass().getName(), f.getName(),
179 f.getType().getName() };
180 throw new EvaluationException(MessageFormat.format(msg,args), x);
181 }
182 catch (IllegalAccessException x) {
183 String msg = "{0}.{1} is not accessible";
184 Object [] args = new Object []{ arg.getClass().getName(), getField(arg).getName()};
185 throw new EvaluationException(MessageFormat.format(msg,args), x);
186 }
187 }
188
189 private Field getField(T arg) {
190 if (_field == null) {
191 try {
192 _field = arg.getClass().getField(_fieldName);
193 }
194 catch (NoSuchFieldException x) {
195 throw new EvaluationException(x);}
196 }
197
198 return _field;
199 }
200
201 private String buildNoSuchFieldMessage(String fieldname, Class clasz) {
202 String msg = "class {0} does not have field {1}";
203 Object [] args = new Object []{ clasz.getName(), fieldname };
204 return MessageFormat.format(msg,args);
205 }
206
207
211 public void accept(net.sf.jga.fn.Visitor v) {
212 if (v instanceof SetField.Visitor)
213 ((SetField.Visitor)v).visit(this);
214 else
215 v.visit(this);
216 }
217
218
220 public String toString() {
221 return "SetField("+_fieldName+")";
222 }
223
224
226
230 public interface Visitor extends net.sf.jga.fn.Visitor {
231 public void visit(SetField host);
232 }
233 }
234 |
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