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33 package net.sf.jga.fn.property;
34
35 import java.lang.reflect.InvocationTargetException  ;
36 import java.lang.reflect.Method ;
37 import java.text.MessageFormat ;
38 import net.sf.jga.fn.EvaluationException;
39 import net.sf.jga.fn.UnaryFunctor;
40
41
49
50 public class GetProperty<T,R> extends UnaryFunctor<T,R> {
51
52 static final long serialVersionUID = -6249123644692001840L;
53
54 private String _propName;
56
57 private String _methName;
59
60 private Class <T> _argtype;
62
63 private transient Method _meth;
65
66
72 public GetProperty(Class <T> argclass, String propName) {
73 if (propName == null || propName.length() == 0) {
74 throw new IllegalArgumentException ("Must supply property name");
75 }
76
77 _argtype = argclass;
78
79 if (propName.startsWith("get")) {
80 _methName = propName;
81 _propName = propName.substring(3);
82 }
83 else if (argclass.equals(Boolean .class) && propName.startsWith("is")) {
84 _methName = propName;
85 _propName = propName.substring(2);
86 }
87 else {
88 _propName = propName;
89 _methName = "get" + propName;
90 }
91
92 try {
93 _meth = argclass.getMethod(_methName, new Class [0]);
94 }
95 catch (NoSuchMethodException x) {
96 String msg = "class {0} does not have property \"{1}\"";
97 Object [] args = new Object []{ argclass.getName(), propName };
98 IllegalArgumentException iax =
99 new IllegalArgumentException (MessageFormat.format(msg,args));
100 iax.initCause(x);
101 throw iax;
102 }
103 }
104
105
108 public String getPropertyName() {
109 return _propName;
110 }
111
112
114
120 public R fn(T arg) {
121 try {
122 R val = (R) getMethod().invoke(arg, new Object [0]);
126 return val;
127 }
128 catch (ClassCastException x) {
129 String msg = "{0}.{1} returns type {2}";
130 Method m = getMethod();
131 Object [] args = new Object []{ _argtype.getName(), m.getName(),
132 m.getReturnType().getName() };
133 throw new EvaluationException(MessageFormat.format(msg,args), x);
134 }
135 catch (IllegalAccessException x) {
136 String msg = "{0}.{1} is not accessible";
137 Object [] args = new Object []{ _argtype.getName(), getMethod().getName()};
138 throw new EvaluationException(MessageFormat.format(msg,args), x);
139 }
140 catch (InvocationTargetException x) {
141 String msg = "{0}.{1} failed : "+x.getMessage();
142 Object [] args = new Object []{ _argtype.getName(), getMethod().getName()};
143 throw new EvaluationException(MessageFormat.format(msg,args), x);
144 }
145 }
146
147 private Method getMethod() {
148 if (_meth == null) {
149 try {
150 _meth = _argtype.getMethod(_methName, new Class [0]);
151 }
152 catch (NoSuchMethodException x) {
153 String msg = "class {0} does not have method {1}";
154 Object [] args = new Object []{ _argtype.getName(), _methName};
155 throw new EvaluationException(MessageFormat.format(msg,args), x);
156 }
157 }
158
159 return _meth;
160 }
161
162
166 public void accept(net.sf.jga.fn.Visitor v) {
167 if (v instanceof GetProperty.Visitor)
168 ((GetProperty.Visitor)v).visit(this);
169 else
170 v.visit(this);
171 }
172
173
175 public String toString() {
176 return "GetProperty["+_propName+"]";
177 }
178
179
181
185 public interface Visitor extends net.sf.jga.fn.Visitor {
186 public void visit(GetProperty host);
187 }
188 }
189 |
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