1 /* 2 * Copyright (c) 2008, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang.invoke; 27 28 import jdk.internal.vm.annotation.Stable; 29 import sun.invoke.util.Wrapper; 30 import java.lang.ref.WeakReference; 31 import java.lang.ref.Reference; 32 import java.lang.ref.ReferenceQueue; 33 import java.util.Arrays; 34 import java.util.Collections; 35 import java.util.List; 36 import java.util.Objects; 37 import java.util.StringJoiner; 38 import java.util.concurrent.ConcurrentMap; 39 import java.util.concurrent.ConcurrentHashMap; 40 import sun.invoke.util.BytecodeDescriptor; 41 import static java.lang.invoke.MethodHandleStatics.*; 42 import sun.invoke.util.VerifyType; 43 44 /** 45 * A method type represents the arguments and return type accepted and 46 * returned by a method handle, or the arguments and return type passed 47 * and expected by a method handle caller. Method types must be properly 48 * matched between a method handle and all its callers, 49 * and the JVM's operations enforce this matching at, specifically 50 * during calls to {@link MethodHandle#invokeExact MethodHandle.invokeExact} 51 * and {@link MethodHandle#invoke MethodHandle.invoke}, and during execution 52 * of {@code invokedynamic} instructions. 53 * <p> 54 * The structure is a return type accompanied by any number of parameter types. 55 * The types (primitive, {@code void}, and reference) are represented by {@link Class} objects. 56 * (For ease of exposition, we treat {@code void} as if it were a type. 57 * In fact, it denotes the absence of a return type.) 58 * <p> 59 * All instances of {@code MethodType} are immutable. 60 * Two instances are completely interchangeable if they compare equal. 61 * Equality depends on pairwise correspondence of the return and parameter types and on nothing else. 62 * <p> 63 * This type can be created only by factory methods. 64 * All factory methods may cache values, though caching is not guaranteed. 65 * Some factory methods are static, while others are virtual methods which 66 * modify precursor method types, e.g., by changing a selected parameter. 67 * <p> 68 * Factory methods which operate on groups of parameter types 69 * are systematically presented in two versions, so that both Java arrays and 70 * Java lists can be used to work with groups of parameter types. 71 * The query methods {@code parameterArray} and {@code parameterList} 72 * also provide a choice between arrays and lists. 73 * <p> 74 * {@code MethodType} objects are sometimes derived from bytecode instructions 75 * such as {@code invokedynamic}, specifically from the type descriptor strings associated 76 * with the instructions in a class file's constant pool. 77 * <p> 78 * Like classes and strings, method types can also be represented directly 79 * in a class file's constant pool as constants. 80 * A method type may be loaded by an {@code ldc} instruction which refers 81 * to a suitable {@code CONSTANT_MethodType} constant pool entry. 82 * The entry refers to a {@code CONSTANT_Utf8} spelling for the descriptor string. 83 * (For full details on method type constants, 84 * see sections 4.4.8 and 5.4.3.5 of the Java Virtual Machine Specification.) 85 * <p> 86 * When the JVM materializes a {@code MethodType} from a descriptor string, 87 * all classes named in the descriptor must be accessible, and will be loaded. 88 * (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.) 89 * This loading may occur at any time before the {@code MethodType} object is first derived. 90 * @author John Rose, JSR 292 EG 91 * @since 1.7 92 */ 93 public final 94 class MethodType implements java.io.Serializable { 95 private static final long serialVersionUID = 292L; // {rtype, {ptype...}} 96 97 // The rtype and ptypes fields define the structural identity of the method type: 98 private final @Stable Class<?> rtype; 99 private final @Stable Class<?>[] ptypes; 100 101 // The remaining fields are caches of various sorts: 102 private @Stable MethodTypeForm form; // erased form, plus cached data about primitives 103 private @Stable MethodType wrapAlt; // alternative wrapped/unwrapped version 104 private @Stable Invokers invokers; // cache of handy higher-order adapters 105 private @Stable String methodDescriptor; // cache for toMethodDescriptorString 106 107 /** 108 * Check the given parameters for validity and store them into the final fields. 109 */ 110 private MethodType(Class<?> rtype, Class<?>[] ptypes, boolean trusted) { 111 checkRtype(rtype); 112 checkPtypes(ptypes); 113 this.rtype = rtype; 114 // defensively copy the array passed in by the user 115 this.ptypes = trusted ? ptypes : Arrays.copyOf(ptypes, ptypes.length); 116 } 117 118 /** 119 * Construct a temporary unchecked instance of MethodType for use only as a key to the intern table. 120 * Does not check the given parameters for validity, and must discarded (if untrusted) or checked 121 * (if trusted) after it has been used as a searching key. 122 * The parameters are reversed for this constructor, so that it is not accidentally used. 123 */ 124 private MethodType(Class<?>[] ptypes, Class<?> rtype) { 125 this.rtype = rtype; 126 this.ptypes = ptypes; 127 } 128 129 /*trusted*/ MethodTypeForm form() { return form; } 130 /*trusted*/ Class<?> rtype() { return rtype; } 131 /*trusted*/ Class<?>[] ptypes() { return ptypes; } 132 133 void setForm(MethodTypeForm f) { form = f; } 134 135 /** This number, mandated by the JVM spec as 255, 136 * is the maximum number of <em>slots</em> 137 * that any Java method can receive in its argument list. 138 * It limits both JVM signatures and method type objects. 139 * The longest possible invocation will look like 140 * {@code staticMethod(arg1, arg2, ..., arg255)} or 141 * {@code x.virtualMethod(arg1, arg2, ..., arg254)}. 142 */ 143 /*non-public*/ static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec. 144 145 /** This number is the maximum arity of a method handle, 254. 146 * It is derived from the absolute JVM-imposed arity by subtracting one, 147 * which is the slot occupied by the method handle itself at the 148 * beginning of the argument list used to invoke the method handle. 149 * The longest possible invocation will look like 150 * {@code mh.invoke(arg1, arg2, ..., arg254)}. 151 */ 152 // Issue: Should we allow MH.invokeWithArguments to go to the full 255? 153 /*non-public*/ static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver 154 155 /** This number is the maximum arity of a method handle invoker, 253. 156 * It is derived from the absolute JVM-imposed arity by subtracting two, 157 * which are the slots occupied by invoke method handle, and the 158 * target method handle, which are both at the beginning of the argument 159 * list used to invoke the target method handle. 160 * The longest possible invocation will look like 161 * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}. 162 */ 163 /*non-public*/ static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker 164 165 private static void checkRtype(Class<?> rtype) { 166 Objects.requireNonNull(rtype); 167 } 168 private static void checkPtype(Class<?> ptype) { 169 Objects.requireNonNull(ptype); 170 if (ptype == void.class) 171 throw newIllegalArgumentException("parameter type cannot be void"); 172 } 173 /** Return number of extra slots (count of long/double args). */ 174 private static int checkPtypes(Class<?>[] ptypes) { 175 int slots = 0; 176 for (Class<?> ptype : ptypes) { 177 checkPtype(ptype); 178 if (ptype == double.class || ptype == long.class) { 179 slots++; 180 } 181 } 182 checkSlotCount(ptypes.length + slots); 183 return slots; 184 } 185 186 static { 187 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work: 188 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0); 189 } 190 static void checkSlotCount(int count) { 191 if ((count & MAX_JVM_ARITY) != count) 192 throw newIllegalArgumentException("bad parameter count "+count); 193 } 194 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) { 195 if (num instanceof Integer) num = "bad index: "+num; 196 return new IndexOutOfBoundsException(num.toString()); 197 } 198 199 static final ConcurrentWeakInternSet<MethodType> internTable = new ConcurrentWeakInternSet<>(); 200 201 static final Class<?>[] NO_PTYPES = {}; 202 203 /** 204 * Finds or creates an instance of the given method type. 205 * @param rtype the return type 206 * @param ptypes the parameter types 207 * @return a method type with the given components 208 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null 209 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class} 210 */ 211 public static 212 MethodType methodType(Class<?> rtype, Class<?>[] ptypes) { 213 return makeImpl(rtype, ptypes, false); 214 } 215 216 /** 217 * Finds or creates a method type with the given components. 218 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 219 * @param rtype the return type 220 * @param ptypes the parameter types 221 * @return a method type with the given components 222 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null 223 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class} 224 */ 225 public static 226 MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) { 227 boolean notrust = false; // random List impl. could return evil ptypes array 228 return makeImpl(rtype, listToArray(ptypes), notrust); 229 } 230 231 private static Class<?>[] listToArray(List<Class<?>> ptypes) { 232 // sanity check the size before the toArray call, since size might be huge 233 checkSlotCount(ptypes.size()); 234 return ptypes.toArray(NO_PTYPES); 235 } 236 237 /** 238 * Finds or creates a method type with the given components. 239 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 240 * The leading parameter type is prepended to the remaining array. 241 * @param rtype the return type 242 * @param ptype0 the first parameter type 243 * @param ptypes the remaining parameter types 244 * @return a method type with the given components 245 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null 246 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class} 247 */ 248 public static 249 MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) { 250 Class<?>[] ptypes1 = new Class<?>[1+ptypes.length]; 251 ptypes1[0] = ptype0; 252 System.arraycopy(ptypes, 0, ptypes1, 1, ptypes.length); 253 return makeImpl(rtype, ptypes1, true); 254 } 255 256 /** 257 * Finds or creates a method type with the given components. 258 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 259 * The resulting method has no parameter types. 260 * @param rtype the return type 261 * @return a method type with the given return value 262 * @throws NullPointerException if {@code rtype} is null 263 */ 264 public static 265 MethodType methodType(Class<?> rtype) { 266 return makeImpl(rtype, NO_PTYPES, true); 267 } 268 269 /** 270 * Finds or creates a method type with the given components. 271 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 272 * The resulting method has the single given parameter type. 273 * @param rtype the return type 274 * @param ptype0 the parameter type 275 * @return a method type with the given return value and parameter type 276 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null 277 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class} 278 */ 279 public static 280 MethodType methodType(Class<?> rtype, Class<?> ptype0) { 281 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true); 282 } 283 284 /** 285 * Finds or creates a method type with the given components. 286 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 287 * The resulting method has the same parameter types as {@code ptypes}, 288 * and the specified return type. 289 * @param rtype the return type 290 * @param ptypes the method type which supplies the parameter types 291 * @return a method type with the given components 292 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null 293 */ 294 public static 295 MethodType methodType(Class<?> rtype, MethodType ptypes) { 296 return makeImpl(rtype, ptypes.ptypes, true); 297 } 298 299 /** 300 * Sole factory method to find or create an interned method type. 301 * @param rtype desired return type 302 * @param ptypes desired parameter types 303 * @param trusted whether the ptypes can be used without cloning 304 * @return the unique method type of the desired structure 305 */ 306 /*trusted*/ static 307 MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) { 308 if (ptypes.length == 0) { 309 ptypes = NO_PTYPES; trusted = true; 310 } 311 MethodType primordialMT = new MethodType(ptypes, rtype); 312 MethodType mt = internTable.get(primordialMT); 313 if (mt != null) 314 return mt; 315 316 // promote the object to the Real Thing, and reprobe 317 if (trusted) { 318 MethodType.checkRtype(rtype); 319 MethodType.checkPtypes(ptypes); 320 mt = primordialMT; 321 } else { 322 mt = new MethodType(rtype, ptypes, false); 323 } 324 mt.form = MethodTypeForm.findForm(mt); 325 return internTable.add(mt); 326 } 327 private static final @Stable MethodType[] objectOnlyTypes = new MethodType[20]; 328 329 /** 330 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array. 331 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 332 * All parameters and the return type will be {@code Object}, 333 * except the final array parameter if any, which will be {@code Object[]}. 334 * @param objectArgCount number of parameters (excluding the final array parameter if any) 335 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]} 336 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments 337 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true) 338 * @see #genericMethodType(int) 339 */ 340 public static 341 MethodType genericMethodType(int objectArgCount, boolean finalArray) { 342 MethodType mt; 343 checkSlotCount(objectArgCount); 344 int ivarargs = (!finalArray ? 0 : 1); 345 int ootIndex = objectArgCount*2 + ivarargs; 346 if (ootIndex < objectOnlyTypes.length) { 347 mt = objectOnlyTypes[ootIndex]; 348 if (mt != null) return mt; 349 } 350 Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs]; 351 Arrays.fill(ptypes, Object.class); 352 if (ivarargs != 0) ptypes[objectArgCount] = Object[].class; 353 mt = makeImpl(Object.class, ptypes, true); 354 if (ootIndex < objectOnlyTypes.length) { 355 objectOnlyTypes[ootIndex] = mt; // cache it here also! 356 } 357 return mt; 358 } 359 360 /** 361 * Finds or creates a method type whose components are all {@code Object}. 362 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 363 * All parameters and the return type will be Object. 364 * @param objectArgCount number of parameters 365 * @return a generally applicable method type, for all calls of the given argument count 366 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 367 * @see #genericMethodType(int, boolean) 368 */ 369 public static 370 MethodType genericMethodType(int objectArgCount) { 371 return genericMethodType(objectArgCount, false); 372 } 373 374 /** 375 * Finds or creates a method type with a single different parameter type. 376 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 377 * @param num the index (zero-based) of the parameter type to change 378 * @param nptype a new parameter type to replace the old one with 379 * @return the same type, except with the selected parameter changed 380 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()} 381 * @throws IllegalArgumentException if {@code nptype} is {@code void.class} 382 * @throws NullPointerException if {@code nptype} is null 383 */ 384 public MethodType changeParameterType(int num, Class<?> nptype) { 385 if (parameterType(num) == nptype) return this; 386 checkPtype(nptype); 387 Class<?>[] nptypes = ptypes.clone(); 388 nptypes[num] = nptype; 389 return makeImpl(rtype, nptypes, true); 390 } 391 392 /** 393 * Finds or creates a method type with additional parameter types. 394 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 395 * @param num the position (zero-based) of the inserted parameter type(s) 396 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 397 * @return the same type, except with the selected parameter(s) inserted 398 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()} 399 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 400 * or if the resulting method type would have more than 255 parameter slots 401 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 402 */ 403 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) { 404 int len = ptypes.length; 405 if (num < 0 || num > len) 406 throw newIndexOutOfBoundsException(num); 407 int ins = checkPtypes(ptypesToInsert); 408 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins); 409 int ilen = ptypesToInsert.length; 410 if (ilen == 0) return this; 411 Class<?>[] nptypes = new Class<?>[len + ilen]; 412 if (num > 0) { 413 System.arraycopy(ptypes, 0, nptypes, 0, num); 414 } 415 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen); 416 if (num < len) { 417 System.arraycopy(ptypes, num, nptypes, num+ilen, len-num); 418 } 419 return makeImpl(rtype, nptypes, true); 420 } 421 422 /** 423 * Finds or creates a method type with additional parameter types. 424 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 425 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list 426 * @return the same type, except with the selected parameter(s) appended 427 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 428 * or if the resulting method type would have more than 255 parameter slots 429 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 430 */ 431 public MethodType appendParameterTypes(Class<?>... ptypesToInsert) { 432 return insertParameterTypes(parameterCount(), ptypesToInsert); 433 } 434 435 /** 436 * Finds or creates a method type with additional parameter types. 437 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 438 * @param num the position (zero-based) of the inserted parameter type(s) 439 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 440 * @return the same type, except with the selected parameter(s) inserted 441 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()} 442 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 443 * or if the resulting method type would have more than 255 parameter slots 444 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 445 */ 446 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) { 447 return insertParameterTypes(num, listToArray(ptypesToInsert)); 448 } 449 450 /** 451 * Finds or creates a method type with additional parameter types. 452 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 453 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list 454 * @return the same type, except with the selected parameter(s) appended 455 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 456 * or if the resulting method type would have more than 255 parameter slots 457 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 458 */ 459 public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) { 460 return insertParameterTypes(parameterCount(), ptypesToInsert); 461 } 462 463 /** 464 * Finds or creates a method type with modified parameter types. 465 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 466 * @param start the position (zero-based) of the first replaced parameter type(s) 467 * @param end the position (zero-based) after the last replaced parameter type(s) 468 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 469 * @return the same type, except with the selected parameter(s) replaced 470 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()} 471 * or if {@code end} is negative or greater than {@code parameterCount()} 472 * or if {@code start} is greater than {@code end} 473 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 474 * or if the resulting method type would have more than 255 parameter slots 475 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 476 */ 477 /*non-public*/ MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) { 478 if (start == end) 479 return insertParameterTypes(start, ptypesToInsert); 480 int len = ptypes.length; 481 if (!(0 <= start && start <= end && end <= len)) 482 throw newIndexOutOfBoundsException("start="+start+" end="+end); 483 int ilen = ptypesToInsert.length; 484 if (ilen == 0) 485 return dropParameterTypes(start, end); 486 return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert); 487 } 488 489 /** Replace the last arrayLength parameter types with the component type of arrayType. 490 * @param arrayType any array type 491 * @param pos position at which to spread 492 * @param arrayLength the number of parameter types to change 493 * @return the resulting type 494 */ 495 /*non-public*/ MethodType asSpreaderType(Class<?> arrayType, int pos, int arrayLength) { 496 assert(parameterCount() >= arrayLength); 497 int spreadPos = pos; 498 if (arrayLength == 0) return this; // nothing to change 499 if (arrayType == Object[].class) { 500 if (isGeneric()) return this; // nothing to change 501 if (spreadPos == 0) { 502 // no leading arguments to preserve; go generic 503 MethodType res = genericMethodType(arrayLength); 504 if (rtype != Object.class) { 505 res = res.changeReturnType(rtype); 506 } 507 return res; 508 } 509 } 510 Class<?> elemType = arrayType.getComponentType(); 511 assert(elemType != null); 512 for (int i = spreadPos; i < spreadPos + arrayLength; i++) { 513 if (ptypes[i] != elemType) { 514 Class<?>[] fixedPtypes = ptypes.clone(); 515 Arrays.fill(fixedPtypes, i, spreadPos + arrayLength, elemType); 516 return methodType(rtype, fixedPtypes); 517 } 518 } 519 return this; // arguments check out; no change 520 } 521 522 /** Return the leading parameter type, which must exist and be a reference. 523 * @return the leading parameter type, after error checks 524 */ 525 /*non-public*/ Class<?> leadingReferenceParameter() { 526 Class<?> ptype; 527 if (ptypes.length == 0 || 528 (ptype = ptypes[0]).isPrimitive()) 529 throw newIllegalArgumentException("no leading reference parameter"); 530 return ptype; 531 } 532 533 /** Delete the last parameter type and replace it with arrayLength copies of the component type of arrayType. 534 * @param arrayType any array type 535 * @param pos position at which to insert parameters 536 * @param arrayLength the number of parameter types to insert 537 * @return the resulting type 538 */ 539 /*non-public*/ MethodType asCollectorType(Class<?> arrayType, int pos, int arrayLength) { 540 assert(parameterCount() >= 1); 541 assert(pos < ptypes.length); 542 assert(ptypes[pos].isAssignableFrom(arrayType)); 543 MethodType res; 544 if (arrayType == Object[].class) { 545 res = genericMethodType(arrayLength); 546 if (rtype != Object.class) { 547 res = res.changeReturnType(rtype); 548 } 549 } else { 550 Class<?> elemType = arrayType.getComponentType(); 551 assert(elemType != null); 552 res = methodType(rtype, Collections.nCopies(arrayLength, elemType)); 553 } 554 if (ptypes.length == 1) { 555 return res; 556 } else { 557 // insert after (if need be), then before 558 if (pos < ptypes.length - 1) { 559 res = res.insertParameterTypes(arrayLength, Arrays.copyOfRange(ptypes, pos + 1, ptypes.length)); 560 } 561 return res.insertParameterTypes(0, Arrays.copyOf(ptypes, pos)); 562 } 563 } 564 565 /** 566 * Finds or creates a method type with some parameter types omitted. 567 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 568 * @param start the index (zero-based) of the first parameter type to remove 569 * @param end the index (greater than {@code start}) of the first parameter type after not to remove 570 * @return the same type, except with the selected parameter(s) removed 571 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()} 572 * or if {@code end} is negative or greater than {@code parameterCount()} 573 * or if {@code start} is greater than {@code end} 574 */ 575 public MethodType dropParameterTypes(int start, int end) { 576 int len = ptypes.length; 577 if (!(0 <= start && start <= end && end <= len)) 578 throw newIndexOutOfBoundsException("start="+start+" end="+end); 579 if (start == end) return this; 580 Class<?>[] nptypes; 581 if (start == 0) { 582 if (end == len) { 583 // drop all parameters 584 nptypes = NO_PTYPES; 585 } else { 586 // drop initial parameter(s) 587 nptypes = Arrays.copyOfRange(ptypes, end, len); 588 } 589 } else { 590 if (end == len) { 591 // drop trailing parameter(s) 592 nptypes = Arrays.copyOfRange(ptypes, 0, start); 593 } else { 594 int tail = len - end; 595 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail); 596 System.arraycopy(ptypes, end, nptypes, start, tail); 597 } 598 } 599 return makeImpl(rtype, nptypes, true); 600 } 601 602 /** 603 * Finds or creates a method type with a different return type. 604 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 605 * @param nrtype a return parameter type to replace the old one with 606 * @return the same type, except with the return type change 607 * @throws NullPointerException if {@code nrtype} is null 608 */ 609 public MethodType changeReturnType(Class<?> nrtype) { 610 if (returnType() == nrtype) return this; 611 return makeImpl(nrtype, ptypes, true); 612 } 613 614 /** 615 * Reports if this type contains a primitive argument or return value. 616 * The return type {@code void} counts as a primitive. 617 * @return true if any of the types are primitives 618 */ 619 public boolean hasPrimitives() { 620 return form.hasPrimitives(); 621 } 622 623 /** 624 * Reports if this type contains a wrapper argument or return value. 625 * Wrappers are types which box primitive values, such as {@link Integer}. 626 * The reference type {@code java.lang.Void} counts as a wrapper, 627 * if it occurs as a return type. 628 * @return true if any of the types are wrappers 629 */ 630 public boolean hasWrappers() { 631 return unwrap() != this; 632 } 633 634 /** 635 * Erases all reference types to {@code Object}. 636 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 637 * All primitive types (including {@code void}) will remain unchanged. 638 * @return a version of the original type with all reference types replaced 639 */ 640 public MethodType erase() { 641 return form.erasedType(); 642 } 643 644 /** 645 * Erases all reference types to {@code Object}, and all subword types to {@code int}. 646 * This is the reduced type polymorphism used by private methods 647 * such as {@link MethodHandle#invokeBasic invokeBasic}. 648 * @return a version of the original type with all reference and subword types replaced 649 */ 650 /*non-public*/ MethodType basicType() { 651 return form.basicType(); 652 } 653 654 private static final @Stable Class<?>[] METHOD_HANDLE_ARRAY 655 = new Class<?>[] { MethodHandle.class }; 656 657 /** 658 * @return a version of the original type with MethodHandle prepended as the first argument 659 */ 660 /*non-public*/ MethodType invokerType() { 661 return insertParameterTypes(0, METHOD_HANDLE_ARRAY); 662 } 663 664 /** 665 * Converts all types, both reference and primitive, to {@code Object}. 666 * Convenience method for {@link #genericMethodType(int) genericMethodType}. 667 * The expression {@code type.wrap().erase()} produces the same value 668 * as {@code type.generic()}. 669 * @return a version of the original type with all types replaced 670 */ 671 public MethodType generic() { 672 return genericMethodType(parameterCount()); 673 } 674 675 /*non-public*/ boolean isGeneric() { 676 return this == erase() && !hasPrimitives(); 677 } 678 679 /** 680 * Converts all primitive types to their corresponding wrapper types. 681 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 682 * All reference types (including wrapper types) will remain unchanged. 683 * A {@code void} return type is changed to the type {@code java.lang.Void}. 684 * The expression {@code type.wrap().erase()} produces the same value 685 * as {@code type.generic()}. 686 * @return a version of the original type with all primitive types replaced 687 */ 688 public MethodType wrap() { 689 return hasPrimitives() ? wrapWithPrims(this) : this; 690 } 691 692 /** 693 * Converts all wrapper types to their corresponding primitive types. 694 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 695 * All primitive types (including {@code void}) will remain unchanged. 696 * A return type of {@code java.lang.Void} is changed to {@code void}. 697 * @return a version of the original type with all wrapper types replaced 698 */ 699 public MethodType unwrap() { 700 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this); 701 return unwrapWithNoPrims(noprims); 702 } 703 704 private static MethodType wrapWithPrims(MethodType pt) { 705 assert(pt.hasPrimitives()); 706 MethodType wt = pt.wrapAlt; 707 if (wt == null) { 708 // fill in lazily 709 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP, MethodTypeForm.WRAP); 710 assert(wt != null); 711 pt.wrapAlt = wt; 712 } 713 return wt; 714 } 715 716 private static MethodType unwrapWithNoPrims(MethodType wt) { 717 assert(!wt.hasPrimitives()); 718 MethodType uwt = wt.wrapAlt; 719 if (uwt == null) { 720 // fill in lazily 721 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP, MethodTypeForm.UNWRAP); 722 if (uwt == null) 723 uwt = wt; // type has no wrappers or prims at all 724 wt.wrapAlt = uwt; 725 } 726 return uwt; 727 } 728 729 /** 730 * Returns the parameter type at the specified index, within this method type. 731 * @param num the index (zero-based) of the desired parameter type 732 * @return the selected parameter type 733 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()} 734 */ 735 public Class<?> parameterType(int num) { 736 return ptypes[num]; 737 } 738 /** 739 * Returns the number of parameter types in this method type. 740 * @return the number of parameter types 741 */ 742 public int parameterCount() { 743 return ptypes.length; 744 } 745 /** 746 * Returns the return type of this method type. 747 * @return the return type 748 */ 749 public Class<?> returnType() { 750 return rtype; 751 } 752 753 /** 754 * Presents the parameter types as a list (a convenience method). 755 * The list will be immutable. 756 * @return the parameter types (as an immutable list) 757 */ 758 public List<Class<?>> parameterList() { 759 return Collections.unmodifiableList(Arrays.asList(ptypes.clone())); 760 } 761 762 /*non-public*/ Class<?> lastParameterType() { 763 int len = ptypes.length; 764 return len == 0 ? void.class : ptypes[len-1]; 765 } 766 767 /** 768 * Presents the parameter types as an array (a convenience method). 769 * Changes to the array will not result in changes to the type. 770 * @return the parameter types (as a fresh copy if necessary) 771 */ 772 public Class<?>[] parameterArray() { 773 return ptypes.clone(); 774 } 775 776 /** 777 * Compares the specified object with this type for equality. 778 * That is, it returns {@code true} if and only if the specified object 779 * is also a method type with exactly the same parameters and return type. 780 * @param x object to compare 781 * @see Object#equals(Object) 782 */ 783 @Override 784 public boolean equals(Object x) { 785 return this == x || x instanceof MethodType && equals((MethodType)x); 786 } 787 788 private boolean equals(MethodType that) { 789 return this.rtype == that.rtype 790 && Arrays.equals(this.ptypes, that.ptypes); 791 } 792 793 /** 794 * Returns the hash code value for this method type. 795 * It is defined to be the same as the hashcode of a List 796 * whose elements are the return type followed by the 797 * parameter types. 798 * @return the hash code value for this method type 799 * @see Object#hashCode() 800 * @see #equals(Object) 801 * @see List#hashCode() 802 */ 803 @Override 804 public int hashCode() { 805 int hashCode = 31 + rtype.hashCode(); 806 for (Class<?> ptype : ptypes) 807 hashCode = 31*hashCode + ptype.hashCode(); 808 return hashCode; 809 } 810 811 /** 812 * Returns a string representation of the method type, 813 * of the form {@code "(PT0,PT1...)RT"}. 814 * The string representation of a method type is a 815 * parenthesis enclosed, comma separated list of type names, 816 * followed immediately by the return type. 817 * <p> 818 * Each type is represented by its 819 * {@link java.lang.Class#getSimpleName simple name}. 820 */ 821 @Override 822 public String toString() { 823 StringJoiner sj = new StringJoiner(",", "(", 824 ")" + rtype.getSimpleName()); 825 for (int i = 0; i < ptypes.length; i++) { 826 sj.add(ptypes[i].getSimpleName()); 827 } 828 return sj.toString(); 829 } 830 831 /** True if my parameter list is effectively identical to the given full list, 832 * after skipping the given number of my own initial parameters. 833 * In other words, after disregarding {@code skipPos} parameters, 834 * my remaining parameter list is no longer than the {@code fullList}, and 835 * is equal to the same-length initial sublist of {@code fullList}. 836 */ 837 /*non-public*/ 838 boolean effectivelyIdenticalParameters(int skipPos, List<Class<?>> fullList) { 839 int myLen = ptypes.length, fullLen = fullList.size(); 840 if (skipPos > myLen || myLen - skipPos > fullLen) 841 return false; 842 List<Class<?>> myList = Arrays.asList(ptypes); 843 if (skipPos != 0) { 844 myList = myList.subList(skipPos, myLen); 845 myLen -= skipPos; 846 } 847 if (fullLen == myLen) 848 return myList.equals(fullList); 849 else 850 return myList.equals(fullList.subList(0, myLen)); 851 } 852 853 /** True if the old return type can always be viewed (w/o casting) under new return type, 854 * and the new parameters can be viewed (w/o casting) under the old parameter types. 855 */ 856 /*non-public*/ 857 boolean isViewableAs(MethodType newType, boolean keepInterfaces) { 858 if (!VerifyType.isNullConversion(returnType(), newType.returnType(), keepInterfaces)) 859 return false; 860 if (form == newType.form && form.erasedType == this) 861 return true; // my reference parameters are all Object 862 if (ptypes == newType.ptypes) 863 return true; 864 int argc = parameterCount(); 865 if (argc != newType.parameterCount()) 866 return false; 867 for (int i = 0; i < argc; i++) { 868 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i), keepInterfaces)) 869 return false; 870 } 871 return true; 872 } 873 /*non-public*/ 874 boolean isConvertibleTo(MethodType newType) { 875 MethodTypeForm oldForm = this.form(); 876 MethodTypeForm newForm = newType.form(); 877 if (oldForm == newForm) 878 // same parameter count, same primitive/object mix 879 return true; 880 if (!canConvert(returnType(), newType.returnType())) 881 return false; 882 Class<?>[] srcTypes = newType.ptypes; 883 Class<?>[] dstTypes = ptypes; 884 if (srcTypes == dstTypes) 885 return true; 886 int argc; 887 if ((argc = srcTypes.length) != dstTypes.length) 888 return false; 889 if (argc <= 1) { 890 if (argc == 1 && !canConvert(srcTypes[0], dstTypes[0])) 891 return false; 892 return true; 893 } 894 if ((oldForm.primitiveParameterCount() == 0 && oldForm.erasedType == this) || 895 (newForm.primitiveParameterCount() == 0 && newForm.erasedType == newType)) { 896 // Somewhat complicated test to avoid a loop of 2 or more trips. 897 // If either type has only Object parameters, we know we can convert. 898 assert(canConvertParameters(srcTypes, dstTypes)); 899 return true; 900 } 901 return canConvertParameters(srcTypes, dstTypes); 902 } 903 904 /** Returns true if MHs.explicitCastArguments produces the same result as MH.asType. 905 * If the type conversion is impossible for either, the result should be false. 906 */ 907 /*non-public*/ 908 boolean explicitCastEquivalentToAsType(MethodType newType) { 909 if (this == newType) return true; 910 if (!explicitCastEquivalentToAsType(rtype, newType.rtype)) { 911 return false; 912 } 913 Class<?>[] srcTypes = newType.ptypes; 914 Class<?>[] dstTypes = ptypes; 915 if (dstTypes == srcTypes) { 916 return true; 917 } 918 assert(dstTypes.length == srcTypes.length); 919 for (int i = 0; i < dstTypes.length; i++) { 920 if (!explicitCastEquivalentToAsType(srcTypes[i], dstTypes[i])) { 921 return false; 922 } 923 } 924 return true; 925 } 926 927 /** Reports true if the src can be converted to the dst, by both asType and MHs.eCE, 928 * and with the same effect. 929 * MHs.eCA has the following "upgrades" to MH.asType: 930 * 1. interfaces are unchecked (that is, treated as if aliased to Object) 931 * Therefore, {@code Object->CharSequence} is possible in both cases but has different semantics 932 * 2. the full matrix of primitive-to-primitive conversions is supported 933 * Narrowing like {@code long->byte} and basic-typing like {@code boolean->int} 934 * are not supported by asType, but anything supported by asType is equivalent 935 * with MHs.eCE. 936 * 3a. unboxing conversions can be followed by the full matrix of primitive conversions 937 * 3b. unboxing of null is permitted (creates a zero primitive value) 938 * Other than interfaces, reference-to-reference conversions are the same. 939 * Boxing primitives to references is the same for both operators. 940 */ 941 private static boolean explicitCastEquivalentToAsType(Class<?> src, Class<?> dst) { 942 if (src == dst || dst == Object.class || dst == void.class) return true; 943 if (src.isPrimitive()) { 944 // Could be a prim/prim conversion, where casting is a strict superset. 945 // Or a boxing conversion, which is always to an exact wrapper class. 946 return canConvert(src, dst); 947 } else if (dst.isPrimitive()) { 948 // Unboxing behavior is different between MHs.eCA & MH.asType (see 3b). 949 return false; 950 } else { 951 // R->R always works, but we have to avoid a check-cast to an interface. 952 return !dst.isInterface() || dst.isAssignableFrom(src); 953 } 954 } 955 956 private boolean canConvertParameters(Class<?>[] srcTypes, Class<?>[] dstTypes) { 957 for (int i = 0; i < srcTypes.length; i++) { 958 if (!canConvert(srcTypes[i], dstTypes[i])) { 959 return false; 960 } 961 } 962 return true; 963 } 964 965 /*non-public*/ 966 static boolean canConvert(Class<?> src, Class<?> dst) { 967 // short-circuit a few cases: 968 if (src == dst || src == Object.class || dst == Object.class) return true; 969 // the remainder of this logic is documented in MethodHandle.asType 970 if (src.isPrimitive()) { 971 // can force void to an explicit null, a la reflect.Method.invoke 972 // can also force void to a primitive zero, by analogy 973 if (src == void.class) return true; //or !dst.isPrimitive()? 974 Wrapper sw = Wrapper.forPrimitiveType(src); 975 if (dst.isPrimitive()) { 976 // P->P must widen 977 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw); 978 } else { 979 // P->R must box and widen 980 return dst.isAssignableFrom(sw.wrapperType()); 981 } 982 } else if (dst.isPrimitive()) { 983 // any value can be dropped 984 if (dst == void.class) return true; 985 Wrapper dw = Wrapper.forPrimitiveType(dst); 986 // R->P must be able to unbox (from a dynamically chosen type) and widen 987 // For example: 988 // Byte/Number/Comparable/Object -> dw:Byte -> byte. 989 // Character/Comparable/Object -> dw:Character -> char 990 // Boolean/Comparable/Object -> dw:Boolean -> boolean 991 // This means that dw must be cast-compatible with src. 992 if (src.isAssignableFrom(dw.wrapperType())) { 993 return true; 994 } 995 // The above does not work if the source reference is strongly typed 996 // to a wrapper whose primitive must be widened. For example: 997 // Byte -> unbox:byte -> short/int/long/float/double 998 // Character -> unbox:char -> int/long/float/double 999 if (Wrapper.isWrapperType(src) && 1000 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) { 1001 // can unbox from src and then widen to dst 1002 return true; 1003 } 1004 // We have already covered cases which arise due to runtime unboxing 1005 // of a reference type which covers several wrapper types: 1006 // Object -> cast:Integer -> unbox:int -> long/float/double 1007 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double 1008 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a 1009 // subclass of Number which wraps a value that can convert to char. 1010 // Since there is none, we don't need an extra check here to cover char or boolean. 1011 return false; 1012 } else { 1013 // R->R always works, since null is always valid dynamically 1014 return true; 1015 } 1016 } 1017 1018 /// Queries which have to do with the bytecode architecture 1019 1020 /** Reports the number of JVM stack slots required to invoke a method 1021 * of this type. Note that (for historical reasons) the JVM requires 1022 * a second stack slot to pass long and double arguments. 1023 * So this method returns {@link #parameterCount() parameterCount} plus the 1024 * number of long and double parameters (if any). 1025 * <p> 1026 * This method is included for the benefit of applications that must 1027 * generate bytecodes that process method handles and invokedynamic. 1028 * @return the number of JVM stack slots for this type's parameters 1029 */ 1030 /*non-public*/ int parameterSlotCount() { 1031 return form.parameterSlotCount(); 1032 } 1033 1034 /*non-public*/ Invokers invokers() { 1035 Invokers inv = invokers; 1036 if (inv != null) return inv; 1037 invokers = inv = new Invokers(this); 1038 return inv; 1039 } 1040 1041 /** Reports the number of JVM stack slots which carry all parameters including and after 1042 * the given position, which must be in the range of 0 to 1043 * {@code parameterCount} inclusive. Successive parameters are 1044 * more shallowly stacked, and parameters are indexed in the bytecodes 1045 * according to their trailing edge. Thus, to obtain the depth 1046 * in the outgoing call stack of parameter {@code N}, obtain 1047 * the {@code parameterSlotDepth} of its trailing edge 1048 * at position {@code N+1}. 1049 * <p> 1050 * Parameters of type {@code long} and {@code double} occupy 1051 * two stack slots (for historical reasons) and all others occupy one. 1052 * Therefore, the number returned is the number of arguments 1053 * <em>including</em> and <em>after</em> the given parameter, 1054 * <em>plus</em> the number of long or double arguments 1055 * at or after the argument for the given parameter. 1056 * <p> 1057 * This method is included for the benefit of applications that must 1058 * generate bytecodes that process method handles and invokedynamic. 1059 * @param num an index (zero-based, inclusive) within the parameter types 1060 * @return the index of the (shallowest) JVM stack slot transmitting the 1061 * given parameter 1062 * @throws IllegalArgumentException if {@code num} is negative or greater than {@code parameterCount()} 1063 */ 1064 /*non-public*/ int parameterSlotDepth(int num) { 1065 if (num < 0 || num > ptypes.length) 1066 parameterType(num); // force a range check 1067 return form.parameterToArgSlot(num-1); 1068 } 1069 1070 /** Reports the number of JVM stack slots required to receive a return value 1071 * from a method of this type. 1072 * If the {@link #returnType() return type} is void, it will be zero, 1073 * else if the return type is long or double, it will be two, else one. 1074 * <p> 1075 * This method is included for the benefit of applications that must 1076 * generate bytecodes that process method handles and invokedynamic. 1077 * @return the number of JVM stack slots (0, 1, or 2) for this type's return value 1078 * Will be removed for PFD. 1079 */ 1080 /*non-public*/ int returnSlotCount() { 1081 return form.returnSlotCount(); 1082 } 1083 1084 /** 1085 * Finds or creates an instance of a method type, given the spelling of its bytecode descriptor. 1086 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 1087 * Any class or interface name embedded in the descriptor string 1088 * will be resolved by calling {@link ClassLoader#loadClass(java.lang.String)} 1089 * on the given loader (or if it is null, on the system class loader). 1090 * <p> 1091 * Note that it is possible to encounter method types which cannot be 1092 * constructed by this method, because their component types are 1093 * not all reachable from a common class loader. 1094 * <p> 1095 * This method is included for the benefit of applications that must 1096 * generate bytecodes that process method handles and {@code invokedynamic}. 1097 * @param descriptor a bytecode-level type descriptor string "(T...)T" 1098 * @param loader the class loader in which to look up the types 1099 * @return a method type matching the bytecode-level type descriptor 1100 * @throws NullPointerException if the string is null 1101 * @throws IllegalArgumentException if the string is not well-formed 1102 * @throws TypeNotPresentException if a named type cannot be found 1103 */ 1104 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader) 1105 throws IllegalArgumentException, TypeNotPresentException 1106 { 1107 return fromDescriptor(descriptor, 1108 (loader == null) ? ClassLoader.getSystemClassLoader() : loader); 1109 } 1110 1111 /** 1112 * Same as {@link #fromMethodDescriptorString(String, ClassLoader)}, but 1113 * {@code null} ClassLoader means the bootstrap loader is used here. 1114 * <p> 1115 * IMPORTANT: This method is preferable for JDK internal use as it more 1116 * correctly interprets {@code null} ClassLoader than 1117 * {@link #fromMethodDescriptorString(String, ClassLoader)}. 1118 * Use of this method also avoids early initialization issues when system 1119 * ClassLoader is not initialized yet. 1120 */ 1121 static MethodType fromDescriptor(String descriptor, ClassLoader loader) 1122 throws IllegalArgumentException, TypeNotPresentException 1123 { 1124 if (!descriptor.startsWith("(") || // also generates NPE if needed 1125 descriptor.indexOf(')') < 0 || 1126 descriptor.indexOf('.') >= 0) 1127 throw newIllegalArgumentException("not a method descriptor: "+descriptor); 1128 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader); 1129 Class<?> rtype = types.remove(types.size() - 1); 1130 Class<?>[] ptypes = listToArray(types); 1131 return makeImpl(rtype, ptypes, true); 1132 } 1133 1134 /** 1135 * Produces a bytecode descriptor representation of the method type. 1136 * <p> 1137 * Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}. 1138 * Two distinct classes which share a common name but have different class loaders 1139 * will appear identical when viewed within descriptor strings. 1140 * <p> 1141 * This method is included for the benefit of applications that must 1142 * generate bytecodes that process method handles and {@code invokedynamic}. 1143 * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString}, 1144 * because the latter requires a suitable class loader argument. 1145 * @return the bytecode type descriptor representation 1146 */ 1147 public String toMethodDescriptorString() { 1148 String desc = methodDescriptor; 1149 if (desc == null) { 1150 desc = BytecodeDescriptor.unparseMethod(this.rtype, this.ptypes); 1151 methodDescriptor = desc; 1152 } 1153 return desc; 1154 } 1155 1156 /*non-public*/ static String toFieldDescriptorString(Class<?> cls) { 1157 return BytecodeDescriptor.unparse(cls); 1158 } 1159 1160 /// Serialization. 1161 1162 /** 1163 * There are no serializable fields for {@code MethodType}. 1164 */ 1165 private static final java.io.ObjectStreamField[] serialPersistentFields = { }; 1166 1167 /** 1168 * Save the {@code MethodType} instance to a stream. 1169 * 1170 * @serialData 1171 * For portability, the serialized format does not refer to named fields. 1172 * Instead, the return type and parameter type arrays are written directly 1173 * from the {@code writeObject} method, using two calls to {@code s.writeObject} 1174 * as follows: 1175 * <blockquote><pre>{@code 1176 s.writeObject(this.returnType()); 1177 s.writeObject(this.parameterArray()); 1178 * }</pre></blockquote> 1179 * <p> 1180 * The deserialized field values are checked as if they were 1181 * provided to the factory method {@link #methodType(Class,Class[]) methodType}. 1182 * For example, null values, or {@code void} parameter types, 1183 * will lead to exceptions during deserialization. 1184 * @param s the stream to write the object to 1185 * @throws java.io.IOException if there is a problem writing the object 1186 */ 1187 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException { 1188 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array 1189 s.writeObject(returnType()); 1190 s.writeObject(parameterArray()); 1191 } 1192 1193 /** 1194 * Reconstitute the {@code MethodType} instance from a stream (that is, 1195 * deserialize it). 1196 * This instance is a scratch object with bogus final fields. 1197 * It provides the parameters to the factory method called by 1198 * {@link #readResolve readResolve}. 1199 * After that call it is discarded. 1200 * @param s the stream to read the object from 1201 * @throws java.io.IOException if there is a problem reading the object 1202 * @throws ClassNotFoundException if one of the component classes cannot be resolved 1203 * @see #MethodType() 1204 * @see #readResolve 1205 * @see #writeObject 1206 */ 1207 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException { 1208 s.defaultReadObject(); // requires serialPersistentFields to be an empty array 1209 1210 Class<?> returnType = (Class<?>) s.readObject(); 1211 Class<?>[] parameterArray = (Class<?>[]) s.readObject(); 1212 1213 // Probably this object will never escape, but let's check 1214 // the field values now, just to be sure. 1215 checkRtype(returnType); 1216 checkPtypes(parameterArray); 1217 1218 parameterArray = parameterArray.clone(); // make sure it is unshared 1219 MethodType_init(returnType, parameterArray); 1220 } 1221 1222 /** 1223 * For serialization only. 1224 * Sets the final fields to null, pending {@code Unsafe.putObject}. 1225 */ 1226 private MethodType() { 1227 this.rtype = null; 1228 this.ptypes = null; 1229 } 1230 private void MethodType_init(Class<?> rtype, Class<?>[] ptypes) { 1231 // In order to communicate these values to readResolve, we must 1232 // store them into the implementation-specific final fields. 1233 checkRtype(rtype); 1234 checkPtypes(ptypes); 1235 UNSAFE.putObject(this, OffsetHolder.rtypeOffset, rtype); 1236 UNSAFE.putObject(this, OffsetHolder.ptypesOffset, ptypes); 1237 } 1238 1239 // Support for resetting final fields while deserializing. Implement Holder 1240 // pattern to make the rarely needed offset calculation lazy. 1241 private static class OffsetHolder { 1242 private static final long rtypeOffset, ptypesOffset; 1243 static { 1244 try { 1245 rtypeOffset = UNSAFE.objectFieldOffset 1246 (MethodType.class.getDeclaredField("rtype")); 1247 ptypesOffset = UNSAFE.objectFieldOffset 1248 (MethodType.class.getDeclaredField("ptypes")); 1249 } catch (Exception ex) { 1250 throw new Error(ex); 1251 } 1252 } 1253 } 1254 1255 /** 1256 * Resolves and initializes a {@code MethodType} object 1257 * after serialization. 1258 * @return the fully initialized {@code MethodType} object 1259 */ 1260 private Object readResolve() { 1261 // Do not use a trusted path for deserialization: 1262 //return makeImpl(rtype, ptypes, true); 1263 // Verify all operands, and make sure ptypes is unshared: 1264 return methodType(rtype, ptypes); 1265 } 1266 1267 /** 1268 * Simple implementation of weak concurrent intern set. 1269 * 1270 * @param <T> interned type 1271 */ 1272 private static class ConcurrentWeakInternSet<T> { 1273 1274 private final ConcurrentMap<WeakEntry<T>, WeakEntry<T>> map; 1275 private final ReferenceQueue<T> stale; 1276 1277 public ConcurrentWeakInternSet() { 1278 this.map = new ConcurrentHashMap<>(512); 1279 this.stale = new ReferenceQueue<>(); 1280 } 1281 1282 /** 1283 * Get the existing interned element. 1284 * This method returns null if no element is interned. 1285 * 1286 * @param elem element to look up 1287 * @return the interned element 1288 */ 1289 public T get(T elem) { 1290 if (elem == null) throw new NullPointerException(); 1291 expungeStaleElements(); 1292 1293 WeakEntry<T> value = map.get(new WeakEntry<>(elem)); 1294 if (value != null) { 1295 T res = value.get(); 1296 if (res != null) { 1297 return res; 1298 } 1299 } 1300 return null; 1301 } 1302 1303 /** 1304 * Interns the element. 1305 * Always returns non-null element, matching the one in the intern set. 1306 * Under the race against another add(), it can return <i>different</i> 1307 * element, if another thread beats us to interning it. 1308 * 1309 * @param elem element to add 1310 * @return element that was actually added 1311 */ 1312 public T add(T elem) { 1313 if (elem == null) throw new NullPointerException(); 1314 1315 // Playing double race here, and so spinloop is required. 1316 // First race is with two concurrent updaters. 1317 // Second race is with GC purging weak ref under our feet. 1318 // Hopefully, we almost always end up with a single pass. 1319 T interned; 1320 WeakEntry<T> e = new WeakEntry<>(elem, stale); 1321 do { 1322 expungeStaleElements(); 1323 WeakEntry<T> exist = map.putIfAbsent(e, e); 1324 interned = (exist == null) ? elem : exist.get(); 1325 } while (interned == null); 1326 return interned; 1327 } 1328 1329 private void expungeStaleElements() { 1330 Reference<? extends T> reference; 1331 while ((reference = stale.poll()) != null) { 1332 map.remove(reference); 1333 } 1334 } 1335 1336 private static class WeakEntry<T> extends WeakReference<T> { 1337 1338 public final int hashcode; 1339 1340 public WeakEntry(T key, ReferenceQueue<T> queue) { 1341 super(key, queue); 1342 hashcode = key.hashCode(); 1343 } 1344 1345 public WeakEntry(T key) { 1346 super(key); 1347 hashcode = key.hashCode(); 1348 } 1349 1350 @Override 1351 public boolean equals(Object obj) { 1352 if (obj instanceof WeakEntry) { 1353 Object that = ((WeakEntry) obj).get(); 1354 Object mine = get(); 1355 return (that == null || mine == null) ? (this == obj) : mine.equals(that); 1356 } 1357 return false; 1358 } 1359 1360 @Override 1361 public int hashCode() { 1362 return hashcode; 1363 } 1364 1365 } 1366 } 1367 1368 }