| %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 |   * @since 1.0 | |
| 35 |   * @version $Id: MethodMap.java 398495 2006-05-01 01:33:43Z dion $ | |
| 36 |   */ | |
| 37 | public class MethodMap { | |
| 38 |      /** whether a method is more specific than a previously compared one. */ | |
| 39 | private static final int MORE_SPECIFIC = 0; | |
| 40 |      /** whether a method is less specific than a previously compared one. */ | |
| 41 | private static final int LESS_SPECIFIC = 1; | |
| 42 |      /** A method doesn't match a previously compared one. */ | |
| 43 | private static final int INCOMPARABLE = 2; | |
| 44 | ||
| 45 |      /** | |
| 46 |       * Keep track of all methods with the same name. | |
| 47 |       */ | |
| 48 | protected Map methodByNameMap = new Hashtable(); | |
| 49 | ||
| 50 |      /** | |
| 51 |       * Add a method to a list of methods by name. For a particular class we are | |
| 52 |       * keeping track of all the methods with the same name. | |
| 53 |       * @param method the method. | |
| 54 |       */ | |
| 55 | public void add(Method method) { | |
| 56 | String methodName = method.getName(); | |
| 57 | ||
| 58 | List l = get(methodName); | |
| 59 | ||
| 60 | if (l == null) { | |
| 61 |              l = new ArrayList(); | |
| 62 | methodByNameMap.put(methodName, l); | |
| 63 | } | |
| 64 | ||
| 65 | l.add(method); | |
| 66 | } | |
| 67 | ||
| 68 |      /** | |
| 69 |       * Return a list of methods with the same name. | |
| 70 |       *  | |
| 71 |       * @param key The method name. | |
| 72 |       * @return List list of methods | |
| 73 |       */ | |
| 74 |      public List get(String key) { | |
| 75 |          return (List) methodByNameMap.get(key); | |
| 76 | } | |
| 77 | ||
| 78 |      /** | |
| 79 |       * <p> | |
| 80 |       * Find a method. Attempts to find the most specific applicable method using | |
| 81 |       * the algorithm described in the JLS section 15.12.2 (with the exception | |
| 82 |       * that it can't distinguish a primitive type argument from an object type | |
| 83 |       * argument, since in reflection primitive type arguments are represented by | |
| 84 |       * their object counterparts, so for an argument of type (say) | |
| 85 |       * java.lang.Integer, it will not be able to decide between a method that | |
| 86 |       * takes int and a method that takes java.lang.Integer as a parameter. | |
| 87 |       * </p> | |
| 88 |       *  | |
| 89 |       * <p> | |
| 90 |       * This turns out to be a relatively rare case where this is needed - | |
| 91 |       * however, functionality like this is needed. | |
| 92 |       * </p> | |
| 93 |       *  | |
| 94 |       * @param methodName name of method | |
| 95 |       * @param args the actual arguments with which the method is called | |
| 96 |       * @return the most specific applicable method, or null if no method is | |
| 97 |       *         applicable. | |
| 98 |       * @throws AmbiguousException if there is more than one maximally specific | |
| 99 |       *             applicable method | |
| 100 |       */ | |
| 101 |      public Method find(String methodName, Object[] args) throws AmbiguousException { | |
| 102 | List methodList = get(methodName); | |
| 103 | ||
| 104 | if (methodList == null) { | |
| 105 | return null; | |
| 106 | } | |
| 107 | ||
| 108 |          int l = args.length; | |
| 109 |          Class[] classes = new Class[l]; | |
| 110 | ||
| 111 | for (int i = 0; i < l; ++i) { | |
| 112 | Object arg = args[i]; | |
| 113 | ||
| 114 |              /* | |
| 115 |               * if we are careful down below, a null argument goes in there so we | |
| 116 |               * can know that the null was passed to the method | |
| 117 |               */ | |
| 118 | classes[i] = arg == null ? class="keyword">null : arg.getClass(); | |
| 119 | } | |
| 120 | ||
| 121 |          return getMostSpecific(methodList, classes); | |
| 122 | } | |
| 123 | ||
| 124 |      /** | |
| 125 |       * simple distinguishable exception, used when we run across ambiguous | |
| 126 |       * overloading. | |
| 127 |       */ | |
| 128 | 0 |      public static class AmbiguousException extends Exception { | 
| 129 |          /** serialization version id jdk13 generated. */ | |
| 130 | static final long serialVersionUID = 8758118091728717367L; | |
| 131 | } | |
| 132 | ||
| 133 |      /** | |
| 134 |       * Gets the most specific method from a list. | |
| 135 |       * @param methods list of {@link Method methods} | |
| 136 |       * @param classes argument types | |
| 137 |       * @return the most specific method, or null | |
| 138 |       * @throws AmbiguousException if there is more than one specific method | |
| 139 |       */ | |
| 140 | private static Method getMostSpecific(List methods, Class[] classes) throws AmbiguousException { | |
| 141 | LinkedList applicables = getApplicables(methods, classes); | |
| 142 | ||
| 143 |          if (applicables.isEmpty()) { | |
| 144 | return null; | |
| 145 | } | |
| 146 | ||
| 147 |          if (applicables.size() == 1) { | |
| 148 |              return (Method) applicables.getFirst(); | |
| 149 | } | |
| 150 | ||
| 151 |          /* | |
| 152 |           * This list will contain the maximally specific methods. Hopefully at | |
| 153 |           * the end of the below loop, the list will contain exactly one method, | |
| 154 |           * (the most specific method) otherwise we have ambiguity. | |
| 155 |           */ | |
| 156 | ||
| 157 |          LinkedList maximals = new LinkedList(); | |
| 158 | ||
| 159 |          for (Iterator applicable = applicables.iterator(); applicable.hasNext();) { | |
| 160 | Method app = (Method) applicable.next(); | |
| 161 | Class[] appArgs = app.getParameterTypes(); | |
| 162 |              boolean lessSpecific = false; | |
| 163 | ||
| 164 |              for (Iterator maximal = maximals.iterator(); !lessSpecific && maximal.hasNext();) { | |
| 165 | Method max = (Method) maximal.next(); | |
| 166 | ||
| 167 |                  switch (moreSpecific(appArgs, max.getParameterTypes())) { | |
| 168 |                      case MORE_SPECIFIC: | |
| 169 |                          /* | |
| 170 |                           * This method is more specific than the previously | |
| 171 |                           * known maximally specific, so remove the old maximum. | |
| 172 |                           */ | |
| 173 | maximal.remove(); | |
| 174 |                          break; | |
| 175 | ||
| 176 |                      case LESS_SPECIFIC: | |
| 177 |                          /* | |
| 178 |                           * This method is less specific than some of the | |
| 179 |                           * currently known maximally specific methods, so we | |
| 180 |                           * won't add it into the set of maximally specific | |
| 181 |                           * methods | |
| 182 |                           */ | |
| 183 |                          lessSpecific = true; | |
| 184 |                          break; | |
| 185 | } | |
| 186 | } | |
| 187 | ||
| 188 | if (!lessSpecclass="keyword">ific) { | |
| 189 | maximals.addLast(app); | |
| 190 | } | |
| 191 | } | |
| 192 | ||
| 193 |          if (maximals.size() > 1) { | |
| 194 |              // We have more than one maximally specific method | |
| 195 | throw new AmbiguousException(); | |
| 196 | } | |
| 197 | ||
| 198 |          return (Method) maximals.getFirst(); | |
| 199 | } | |
| 200 | ||
| 201 |      /** | |
| 202 |       * Determines which method signature (represented by a class array) is more | |
| 203 |       * specific. This defines a partial ordering on the method signatures. | |
| 204 |       *  | |
| 205 |       * @param c1 first signature to compare | |
| 206 |       * @param c2 second signature to compare | |
| 207 |       * @return MORE_SPECIFIC if c1 is more specific than c2, LESS_SPECIFIC if c1 | |
| 208 |       *         is less specific than c2, INCOMPARABLE if they are incomparable. | |
| 209 |       */ | |
| 210 | private static int moreSpecific(Class[] c1, Class[] c2) { | |
| 211 |          boolean c1MoreSpecific = false; | |
| 212 |          boolean c2MoreSpecific = false; | |
| 213 | ||
| 214 | for (int i = 0; i < c1.length; ++i) { | |
| 215 |              if (c1[i] != c2[i]) { | |
| 216 | c1MoreSpecific = c1MoreSpecific || isStrictMethodInvocationConvertible(c2[i], c1[i]); | |
| 217 | c2MoreSpecific = c2MoreSpecific || isStrictMethodInvocationConvertible(c1[i], c2[i]); | |
| 218 | } | |
| 219 | } | |
| 220 | ||
| 221 | if (c1MoreSpecclass="keyword">ific) { | |
| 222 | if (c2MoreSpecclass="keyword">ific) { | |
| 223 |                  /* | |
| 224 |                   * Incomparable due to cross-assignable arguments (i.e. | |
| 225 |                   * foo(String, Object) vs. foo(Object, String)) | |
| 226 |                   */ | |
| 227 | ||
| 228 |                  return INCOMPARABLE; | |
| 229 | } | |
| 230 | ||
| 231 |              return MORE_SPECIFIC; | |
| 232 | } | |
| 233 | ||
| 234 | if (c2MoreSpecclass="keyword">ific) { | |
| 235 |              return LESS_SPECIFIC; | |
| 236 | } | |
| 237 | ||
| 238 |          /* | |
| 239 |           * Incomparable due to non-related arguments (i.e. foo(Runnable) vs. | |
| 240 |           * foo(Serializable)) | |
| 241 |           */ | |
| 242 | ||
| 243 |          return INCOMPARABLE; | |
| 244 | } | |
| 245 | ||
| 246 |      /** | |
| 247 |       * Returns all methods that are applicable to actual argument types. | |
| 248 |       *  | |
| 249 |       * @param methods list of all candidate methods | |
| 250 |       * @param classes the actual types of the arguments | |
| 251 |       * @return a list that contains only applicable methods (number of formal | |
| 252 |       *         and actual arguments matches, and argument types are assignable | |
| 253 |       *         to formal types through a method invocation conversion). | |
| 254 |       */ | |
| 255 | private static LinkedList getApplicables(List methods, Class[] classes) { | |
| 256 |          LinkedList list = new LinkedList(); | |
| 257 | ||
| 258 |          for (Iterator imethod = methods.iterator(); imethod.hasNext();) { | |
| 259 | Method method = (Method) imethod.next(); | |
| 260 | ||
| 261 |              if (isApplicable(method, classes)) { | |
| 262 | list.add(method); | |
| 263 | } | |
| 264 | ||
| 265 | } | |
| 266 |          return list; | |
| 267 | } | |
| 268 | ||
| 269 |      /** | |
| 270 |       * Returns true if the supplied method is applicable to actual argument | |
| 271 |       * types. | |
| 272 |       * @param method the method to check | |
| 273 |       * @param classes possible argument types | |
| 274 |       * @return true if the arguments are applicable to the method. | |
| 275 |       */ | |
| 276 | private static boolean isApplicable(Method method, Class[] classes) { | |
| 277 | Class[] methodArgs = method.getParameterTypes(); | |
| 278 | ||
| 279 |          if (methodArgs.length != classes.length) { | |
| 280 |              return false; | |
| 281 | } | |
| 282 | ||
| 283 | for (int i = 0; i < classes.length; ++i) { | |
| 284 |              if (!isMethodInvocationConvertible(methodArgs[i], classes[i])) { | |
| 285 |                  return false; | |
| 286 | } | |
| 287 | } | |
| 288 | ||
| 289 | return true; | |
| 290 | } | |
| 291 | ||
| 292 |      /** | |
| 293 |       * Determines whether a type represented by a class object is convertible to | |
| 294 |       * another type represented by a class object using a method invocation | |
| 295 |       * conversion, treating object types of primitive types as if they were | |
| 296 |       * primitive types (that is, a Boolean actual parameter type matches boolean | |
| 297 |       * primitive formal type). This behavior is because this method is used to | |
| 298 |       * determine applicable methods for an actual parameter list, and primitive | |
| 299 |       * types are represented by their object duals in reflective method calls. | |
| 300 |       *  | |
| 301 |       * @param formal the formal parameter type to which the actual parameter | |
| 302 |       *            type should be convertible | |
| 303 |       * @param actual the actual parameter type. | |
| 304 |       * @return true if either formal type is assignable from actual type, or | |
| 305 |       *         formal is a primitive type and actual is its corresponding object | |
| 306 |       *         type or an object type of a primitive type that can be converted | |
| 307 |       *         to the formal type. | |
| 308 |       */ | |
| 309 | private static boolean isMethodInvocationConvertible(Class formal, Class actual) { | |
| 310 |          /* | |
| 311 |           * if it's a null, it means the arg was null | |
| 312 |           */ | |
| 313 | if (actual == null && !formal.isPrimitive()) { | |
| 314 | return true; | |
| 315 | } | |
| 316 | ||
| 317 |          /* | |
| 318 |           * Check for identity or widening reference conversion | |
| 319 |           */ | |
| 320 | ||
| 321 | if (actual != null && formal.isAssignableFrom(actual)) { | |
| 322 | return true; | |
| 323 | } | |
| 324 | ||
| 325 |          /* | |
| 326 |           * Check for boxing with widening primitive conversion. Note that actual | |
| 327 |           * parameters are never primitives. | |
| 328 |           */ | |
| 329 | ||
| 330 |          if (formal.isPrimitive()) { | |
| 331 | if (formal == Boolean.TYPE && actual == Boolean.class) { | |
| 332 | return true; | |
| 333 | } | |
| 334 | if (formal == Character.TYPE && actual == Character.class) { | |
| 335 | return true; | |
| 336 | } | |
| 337 | if (formal == Byte.TYPE && actual == Byte.class) { | |
| 338 | return true; | |
| 339 | } | |
| 340 | if (formal == Short.TYPE && (actual == Short.class || actual == Byte.class)) { | |
| 341 | return true; | |
| 342 | } | |
| 343 | if (formal == Integer.TYPE && (actual == Integer.class || actual == Short.class || actual == Byte.class)) { | |
| 344 | return true; | |
| 345 | } | |
| 346 |              if (formal == Long.TYPE | |
| 347 | && (actual == Long.class || actual == Integer.class || actual == Short.class || actual == Byte.class)) { | |
| 348 | return true; | |
| 349 | } | |
| 350 |              if (formal == Float.TYPE | |
| 351 | && (actual == Float.class || actual == Long.class || actual == Integer.class | |
| 352 | || actual == Short.class || actual == Byte.class)) { | |
| 353 | return true; | |
| 354 | } | |
| 355 |              if (formal == Double.TYPE | |
| 356 | && (actual == Double.class || actual == Float.class || actual == Long.class || actual == Integer.class | |
| 357 | || actual == Short.class || actual == Byte.class)) { | |
| 358 | return true; | |
| 359 | } | |
| 360 | } | |
| 361 | ||
| 362 |          return false; | |
| 363 | } | |
| 364 | ||
| 365 |      /** | |
| 366 |       * Determines whether a type represented by a class object is convertible to | |
| 367 |       * another type represented by a class object using a method invocation | |
| 368 |       * conversion, without matching object and primitive types. This method is | |
| 369 |       * used to determine the more specific type when comparing signatures of | |
| 370 |       * methods. | |
| 371 |       *  | |
| 372 |       * @param formal the formal parameter type to which the actual parameter | |
| 373 |       *            type should be convertible | |
| 374 |       * @param actual the actual parameter type. | |
| 375 |       * @return true if either formal type is assignable from actual type, or | |
| 376 |       *         formal and actual are both primitive types and actual can be | |
| 377 |       *         subject to widening conversion to formal. | |
| 378 |       */ | |
| 379 | private static boolean isStrictMethodInvocationConvertible(Class formal, Class actual) { | |
| 380 |          /* | |
| 381 |           * we shouldn't get a null into, but if so | |
| 382 |           */ | |
| 383 | if (actual == null && !formal.isPrimitive()) { | |
| 384 | return true; | |
| 385 | } | |
| 386 | ||
| 387 |          /* | |
| 388 |           * Check for identity or widening reference conversion | |
| 389 |           */ | |
| 390 | ||
| 391 |          if (formal.isAssignableFrom(actual)) { | |
| 392 | return true; | |
| 393 | } | |
| 394 | ||
| 395 |          /* | |
| 396 |           * Check for widening primitive conversion. | |
| 397 |           */ | |
| 398 | ||
| 399 |          if (formal.isPrimitive()) { | |
| 400 |              if (formal == Short.TYPE && (actual == Byte.TYPE)) { | |
| 401 | return true; | |
| 402 | } | |
| 403 |              if (formal == Integer.TYPE && (actual == Short.TYPE || actual == Byte.TYPE)) { | |
| 404 | return true; | |
| 405 | } | |
| 406 |              if (formal == Long.TYPE && (actual == Integer.TYPE || actual == Short.TYPE || actual == Byte.TYPE)) { | |
| 407 | return true; | |
| 408 | } | |
| 409 |              if (formal == Float.TYPE | |
| 410 |                  && (actual == Long.TYPE || actual == Integer.TYPE || actual == Short.TYPE || actual == Byte.TYPE)) { | |
| 411 | return true; | |
| 412 | } | |
| 413 |              if (formal == Double.TYPE | |
| 414 | && (actual == Float.TYPE || actual == Long.TYPE || actual == Integer.TYPE || actual == Short.TYPE | |
| 415 |                      || actual == Byte.TYPE)) { | |
| 416 | return true; | |
| 417 | } | |
| 418 | } | |
| 419 |          return false; | |
| 420 | } | |
| 421 | } | 
| This report is generated by jcoverage, Maven and Maven JCoverage Plugin. |