%line | %branch | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
org.apache.commons.jexl.util.introspection.MethodMap$AmbiguousException |
|
|
1 | /* |
|
2 | * Copyright 2001,2004 The Apache Software Foundation. |
|
3 | * |
|
4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
|
5 | * you may not use this file except in compliance with the License. |
|
6 | * You may obtain a copy of the License at |
|
7 | * |
|
8 | * http://www.apache.org/licenses/LICENSE-2.0 |
|
9 | * |
|
10 | * Unless required by applicable law or agreed to in writing, software |
|
11 | * distributed under the License is distributed on an "AS IS" BASIS, |
|
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
|
13 | * See the License for the specific language governing permissions and |
|
14 | * limitations under the License. |
|
15 | */ |
|
16 | ||
17 | package org.apache.commons.jexl.util.introspection; |
|
18 | ||
19 | import java.lang.reflect.Method; |
|
20 | import java.util.ArrayList; |
|
21 | import java.util.Hashtable; |
|
22 | import java.util.Iterator; |
|
23 | import java.util.LinkedList; |
|
24 | import java.util.List; |
|
25 | import java.util.Map; |
|
26 | ||
27 | /** |
|
28 | * |
|
29 | * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a> |
|
30 | * @author <a href="mailto:bob@werken.com">Bob McWhirter</a> |
|
31 | * @author <a href="mailto:Christoph.Reck@dlr.de">Christoph Reck</a> |
|
32 | * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a> |
|
33 | * @author <a href="mailto:szegedia@freemail.hu">Attila Szegedi</a> |
|
34 | * @version $Id: MethodMap.java,v 1.5 2004/08/19 17:15:59 dion Exp $ |
|
35 | */ |
|
36 | public class MethodMap |
|
37 | { |
|
38 | private static final int MORE_SPECIFIC = 0; |
|
39 | private static final int LESS_SPECIFIC = 1; |
|
40 | private static final int INCOMPARABLE = 2; |
|
41 | ||
42 | /** |
|
43 | * Keep track of all methods with the same name. |
|
44 | */ |
|
45 | Map methodByNameMap = new Hashtable(); |
|
46 | ||
47 | /** |
|
48 | * Add a method to a list of methods by name. |
|
49 | * For a particular class we are keeping track |
|
50 | * of all the methods with the same name. |
|
51 | */ |
|
52 | public void add(Method method) |
|
53 | { |
|
54 | String methodName = method.getName(); |
|
55 | ||
56 | List l = get( methodName ); |
|
57 | ||
58 | if ( l == null) |
|
59 | { |
|
60 | l = new ArrayList(); |
|
61 | methodByNameMap.put(methodName, l); |
|
62 | } |
|
63 | ||
64 | l.add(method); |
|
65 | } |
|
66 | ||
67 | /** |
|
68 | * Return a list of methods with the same name. |
|
69 | * |
|
70 | * @param String key |
|
71 | * @return List list of methods |
|
72 | */ |
|
73 | public List get(String key) |
|
74 | { |
|
75 | return (List) methodByNameMap.get(key); |
|
76 | } |
|
77 | ||
78 | /** |
|
79 | * <p> |
|
80 | * Find a method. Attempts to find the |
|
81 | * most specific applicable method using the |
|
82 | * algorithm described in the JLS section |
|
83 | * 15.12.2 (with the exception that it can't |
|
84 | * distinguish a primitive type argument from |
|
85 | * an object type argument, since in reflection |
|
86 | * primitive type arguments are represented by |
|
87 | * their object counterparts, so for an argument of |
|
88 | * type (say) java.lang.Integer, it will not be able |
|
89 | * to decide between a method that takes int and a |
|
90 | * method that takes java.lang.Integer as a parameter. |
|
91 | * </p> |
|
92 | * |
|
93 | * <p> |
|
94 | * This turns out to be a relatively rare case |
|
95 | * where this is needed - however, functionality |
|
96 | * like this is needed. |
|
97 | * </p> |
|
98 | * |
|
99 | * @param methodName name of method |
|
100 | * @param args the actual arguments with which the method is called |
|
101 | * @return the most specific applicable method, or null if no |
|
102 | * method is applicable. |
|
103 | * @throws AmbiguousException if there is more than one maximally |
|
104 | * specific applicable method |
|
105 | */ |
|
106 | public Method find(String methodName, Object[] args) |
|
107 | throws AmbiguousException |
|
108 | { |
|
109 | List methodList = get(methodName); |
|
110 | ||
111 | if (methodList == null) |
|
112 | { |
|
113 | return null; |
|
114 | } |
|
115 | ||
116 | int l = args.length; |
|
117 | Class[] classes = new Class[l]; |
|
118 | ||
119 | for(int i = 0; i < l; ++i) |
|
120 | { |
|
121 | Object arg = args[i]; |
|
122 | ||
123 | /* |
|
124 | * if we are careful down below, a null argument goes in there |
|
125 | * so we can know that the null was passed to the method |
|
126 | */ |
|
127 | classes[i] = |
|
128 | arg == null ? class="keyword">null : arg.getClass(); |
|
129 | } |
|
130 | ||
131 | return getMostSpecific(methodList, classes); |
|
132 | } |
|
133 | ||
134 | /** |
|
135 | * simple distinguishable exception, used when |
|
136 | * we run across ambiguous overloading |
|
137 | */ |
|
138 | 0 | public static class AmbiguousException extends Exception |
139 | { |
|
140 | } |
|
141 | ||
142 | ||
143 | private static Method getMostSpecific(List methods, Class[] classes) |
|
144 | throws AmbiguousException |
|
145 | { |
|
146 | LinkedList applicables = getApplicables(methods, classes); |
|
147 | ||
148 | if(applicables.isEmpty()) |
|
149 | { |
|
150 | return null; |
|
151 | } |
|
152 | ||
153 | if(applicables.size() == 1) |
|
154 | { |
|
155 | return (Method)applicables.getFirst(); |
|
156 | } |
|
157 | ||
158 | /* |
|
159 | * This list will contain the maximally specific methods. Hopefully at |
|
160 | * the end of the below loop, the list will contain exactly one method, |
|
161 | * (the most specific method) otherwise we have ambiguity. |
|
162 | */ |
|
163 | ||
164 | LinkedList maximals = new LinkedList(); |
|
165 | ||
166 | for (Iterator applicable = applicables.iterator(); |
|
167 | applicable.hasNext();) |
|
168 | { |
|
169 | Method app = (Method) applicable.next(); |
|
170 | Class[] appArgs = app.getParameterTypes(); |
|
171 | boolean lessSpecific = false; |
|
172 | ||
173 | for (Iterator maximal = maximals.iterator(); |
|
174 | !lessSpecific && maximal.hasNext();) |
|
175 | { |
|
176 | Method max = (Method) maximal.next(); |
|
177 | ||
178 | switch(moreSpecific(appArgs, max.getParameterTypes())) |
|
179 | { |
|
180 | case MORE_SPECIFIC: |
|
181 | { |
|
182 | /* |
|
183 | * This method is more specific than the previously |
|
184 | * known maximally specific, so remove the old maximum. |
|
185 | */ |
|
186 | ||
187 | maximal.remove(); |
|
188 | break; |
|
189 | } |
|
190 | ||
191 | case LESS_SPECIFIC: |
|
192 | { |
|
193 | /* |
|
194 | * This method is less specific than some of the |
|
195 | * currently known maximally specific methods, so we |
|
196 | * won't add it into the set of maximally specific |
|
197 | * methods |
|
198 | */ |
|
199 | ||
200 | lessSpecific = true; |
|
201 | break; |
|
202 | } |
|
203 | } |
|
204 | } |
|
205 | ||
206 | if(!lessSpecclass="keyword">ific) |
|
207 | { |
|
208 | maximals.addLast(app); |
|
209 | } |
|
210 | } |
|
211 | ||
212 | if(maximals.size() > 1) |
|
213 | { |
|
214 | // We have more than one maximally specific method |
|
215 | throw new AmbiguousException(); |
|
216 | } |
|
217 | ||
218 | return (Method)maximals.getFirst(); |
|
219 | } |
|
220 | ||
221 | /** |
|
222 | * Determines which method signature (represented by a class array) is more |
|
223 | * specific. This defines a partial ordering on the method signatures. |
|
224 | * @param c1 first signature to compare |
|
225 | * @param c2 second signature to compare |
|
226 | * @return MORE_SPECIFIC if c1 is more specific than c2, LESS_SPECIFIC if |
|
227 | * c1 is less specific than c2, INCOMPARABLE if they are incomparable. |
|
228 | */ |
|
229 | private static int moreSpecific(Class[] c1, Class[] c2) |
|
230 | { |
|
231 | boolean c1MoreSpecific = false; |
|
232 | boolean c2MoreSpecific = false; |
|
233 | ||
234 | for(int i = 0; i < c1.length; ++i) |
|
235 | { |
|
236 | if(c1[i] != c2[i]) |
|
237 | { |
|
238 | c1MoreSpecific = |
|
239 | c1MoreSpecific || |
|
240 | isStrictMethodInvocationConvertible(c2[i], c1[i]); |
|
241 | c2MoreSpecific = |
|
242 | c2MoreSpecific || |
|
243 | isStrictMethodInvocationConvertible(c1[i], c2[i]); |
|
244 | } |
|
245 | } |
|
246 | ||
247 | if(c1MoreSpecclass="keyword">ific) |
|
248 | { |
|
249 | if(c2MoreSpecclass="keyword">ific) |
|
250 | { |
|
251 | /* |
|
252 | * Incomparable due to cross-assignable arguments (i.e. |
|
253 | * foo(String, Object) vs. foo(Object, String)) |
|
254 | */ |
|
255 | ||
256 | return INCOMPARABLE; |
|
257 | } |
|
258 | ||
259 | return MORE_SPECIFIC; |
|
260 | } |
|
261 | ||
262 | if(c2MoreSpecclass="keyword">ific) |
|
263 | { |
|
264 | return LESS_SPECIFIC; |
|
265 | } |
|
266 | ||
267 | /* |
|
268 | * Incomparable due to non-related arguments (i.e. |
|
269 | * foo(Runnable) vs. foo(Serializable)) |
|
270 | */ |
|
271 | ||
272 | return INCOMPARABLE; |
|
273 | } |
|
274 | ||
275 | /** |
|
276 | * Returns all methods that are applicable to actual argument types. |
|
277 | * @param methods list of all candidate methods |
|
278 | * @param classes the actual types of the arguments |
|
279 | * @return a list that contains only applicable methods (number of |
|
280 | * formal and actual arguments matches, and argument types are assignable |
|
281 | * to formal types through a method invocation conversion). |
|
282 | */ |
|
283 | private static LinkedList getApplicables(List methods, Class[] classes) |
|
284 | { |
|
285 | LinkedList list = new LinkedList(); |
|
286 | ||
287 | for (Iterator imethod = methods.iterator(); imethod.hasNext();) |
|
288 | { |
|
289 | Method method = (Method) imethod.next(); |
|
290 | ||
291 | if(isApplicable(method, classes)) |
|
292 | { |
|
293 | list.add(method); |
|
294 | } |
|
295 | ||
296 | } |
|
297 | return list; |
|
298 | } |
|
299 | ||
300 | /** |
|
301 | * Returns true if the supplied method is applicable to actual |
|
302 | * argument types. |
|
303 | */ |
|
304 | private static boolean isApplicable(Method method, Class[] classes) |
|
305 | { |
|
306 | Class[] methodArgs = method.getParameterTypes(); |
|
307 | ||
308 | if(methodArgs.length != classes.length) |
|
309 | { |
|
310 | return false; |
|
311 | } |
|
312 | ||
313 | for(int i = 0; i < classes.length; ++i) |
|
314 | { |
|
315 | if(!isMethodInvocationConvertible(methodArgs[i], classes[i])) |
|
316 | { |
|
317 | return false; |
|
318 | } |
|
319 | } |
|
320 | ||
321 | return true; |
|
322 | } |
|
323 | ||
324 | /** |
|
325 | * Determines whether a type represented by a class object is |
|
326 | * convertible to another type represented by a class object using a |
|
327 | * method invocation conversion, treating object types of primitive |
|
328 | * types as if they were primitive types (that is, a Boolean actual |
|
329 | * parameter type matches boolean primitive formal type). This behavior |
|
330 | * is because this method is used to determine applicable methods for |
|
331 | * an actual parameter list, and primitive types are represented by |
|
332 | * their object duals in reflective method calls. |
|
333 | * |
|
334 | * @param formal the formal parameter type to which the actual |
|
335 | * parameter type should be convertible |
|
336 | * @param actual the actual parameter type. |
|
337 | * @return true if either formal type is assignable from actual type, |
|
338 | * or formal is a primitive type and actual is its corresponding object |
|
339 | * type or an object type of a primitive type that can be converted to |
|
340 | * the formal type. |
|
341 | */ |
|
342 | private static boolean isMethodInvocationConvertible(Class formal, |
|
343 | Class actual) |
|
344 | { |
|
345 | /* |
|
346 | * if it's a null, it means the arg was null |
|
347 | */ |
|
348 | if (actual == null && !formal.isPrimitive()) |
|
349 | { |
|
350 | return true; |
|
351 | } |
|
352 | ||
353 | /* |
|
354 | * Check for identity or widening reference conversion |
|
355 | */ |
|
356 | ||
357 | if (actual != null && formal.isAssignableFrom(actual)) |
|
358 | { |
|
359 | return true; |
|
360 | } |
|
361 | ||
362 | /* |
|
363 | * Check for boxing with widening primitive conversion. Note that |
|
364 | * actual parameters are never primitives. |
|
365 | */ |
|
366 | ||
367 | if (formal.isPrimitive()) |
|
368 | { |
|
369 | if(formal == Boolean.TYPE && actual == Boolean.class) |
|
370 | return true; |
|
371 | if(formal == Character.TYPE && actual == Character.class) |
|
372 | return true; |
|
373 | if(formal == Byte.TYPE && actual == Byte.class) |
|
374 | return true; |
|
375 | if(formal == Short.TYPE && |
|
376 | (actual == Short.class || actual == Byte.class)) |
|
377 | return true; |
|
378 | if(formal == Integer.TYPE && |
|
379 | (actual == Integer.class || actual == Short.class || |
|
380 | actual == Byte.class)) |
|
381 | return true; |
|
382 | if(formal == Long.TYPE && |
|
383 | (actual == Long.class || actual == Integer.class || |
|
384 | actual == Short.class || actual == Byte.class)) |
|
385 | return true; |
|
386 | if(formal == Float.TYPE && |
|
387 | (actual == Float.class || actual == Long.class || |
|
388 | actual == Integer.class || actual == Short.class || |
|
389 | actual == Byte.class)) |
|
390 | return true; |
|
391 | if(formal == Double.TYPE && |
|
392 | (actual == Double.class || actual == Float.class || |
|
393 | actual == Long.class || actual == Integer.class || |
|
394 | actual == Short.class || actual == Byte.class)) |
|
395 | return true; |
|
396 | } |
|
397 | ||
398 | return false; |
|
399 | } |
|
400 | ||
401 | /** |
|
402 | * Determines whether a type represented by a class object is |
|
403 | * convertible to another type represented by a class object using a |
|
404 | * method invocation conversion, without matching object and primitive |
|
405 | * types. This method is used to determine the more specific type when |
|
406 | * comparing signatures of methods. |
|
407 | * |
|
408 | * @param formal the formal parameter type to which the actual |
|
409 | * parameter type should be convertible |
|
410 | * @param actual the actual parameter type. |
|
411 | * @return true if either formal type is assignable from actual type, |
|
412 | * or formal and actual are both primitive types and actual can be |
|
413 | * subject to widening conversion to formal. |
|
414 | */ |
|
415 | private static boolean isStrictMethodInvocationConvertible(Class formal, |
|
416 | Class actual) |
|
417 | { |
|
418 | /* |
|
419 | * we shouldn't get a null into, but if so |
|
420 | */ |
|
421 | if (actual == null && !formal.isPrimitive()) |
|
422 | { |
|
423 | return true; |
|
424 | } |
|
425 | ||
426 | /* |
|
427 | * Check for identity or widening reference conversion |
|
428 | */ |
|
429 | ||
430 | if(formal.isAssignableFrom(actual)) |
|
431 | { |
|
432 | return true; |
|
433 | } |
|
434 | ||
435 | /* |
|
436 | * Check for widening primitive conversion. |
|
437 | */ |
|
438 | ||
439 | if(formal.isPrimitive()) |
|
440 | { |
|
441 | if(formal == Short.TYPE && (actual == Byte.TYPE)) |
|
442 | return true; |
|
443 | if(formal == Integer.TYPE && |
|
444 | (actual == Short.TYPE || actual == Byte.TYPE)) |
|
445 | return true; |
|
446 | if(formal == Long.TYPE && |
|
447 | (actual == Integer.TYPE || actual == Short.TYPE || |
|
448 | actual == Byte.TYPE)) |
|
449 | return true; |
|
450 | if(formal == Float.TYPE && |
|
451 | (actual == Long.TYPE || actual == Integer.TYPE || |
|
452 | actual == Short.TYPE || actual == Byte.TYPE)) |
|
453 | return true; |
|
454 | if(formal == Double.TYPE && |
|
455 | (actual == Float.TYPE || actual == Long.TYPE || |
|
456 | actual == Integer.TYPE || actual == Short.TYPE || |
|
457 | actual == Byte.TYPE)) |
|
458 | return true; |
|
459 | } |
|
460 | return false; |
|
461 | } |
|
462 | } |
This report is generated by jcoverage, Maven and Maven JCoverage Plugin. |