1 /* 2 * Copyright (c) 2008, 2020, 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 java.lang.constant.ClassDesc; 29 import java.lang.constant.Constable; 30 import java.lang.constant.MethodTypeDesc; 31 import java.lang.ref.Reference; 32 import java.lang.ref.ReferenceQueue; 33 import java.lang.ref.WeakReference; 34 import java.util.Arrays; 35 import java.util.Collections; 36 import java.util.List; 37 import java.util.NoSuchElementException; 38 import java.util.Objects; 39 import java.util.Optional; 40 import java.util.StringJoiner; 41 import java.util.concurrent.ConcurrentHashMap; 42 import java.util.concurrent.ConcurrentMap; 43 import java.util.stream.Stream; 44 45 import jdk.internal.vm.annotation.Stable; 46 import sun.invoke.util.BytecodeDescriptor; 47 import sun.invoke.util.VerifyType; 48 import sun.invoke.util.Wrapper; 49 import sun.security.util.SecurityConstants; 50 51 import static java.lang.invoke.MethodHandleStatics.UNSAFE; 52 import static java.lang.invoke.MethodHandleStatics.newIllegalArgumentException; 53 import static java.lang.invoke.MethodType.fromDescriptor; 54 55 /** 56 * A method type represents the arguments and return type accepted and 57 * returned by a method handle, or the arguments and return type passed 58 * and expected by a method handle caller. Method types must be properly 59 * matched between a method handle and all its callers, 60 * and the JVM's operations enforce this matching at, specifically 61 * during calls to {@link MethodHandle#invokeExact MethodHandle.invokeExact} 62 * and {@link MethodHandle#invoke MethodHandle.invoke}, and during execution 63 * of {@code invokedynamic} instructions. 64 * <p> 65 * The structure is a return type accompanied by any number of parameter types. 66 * The types (primitive, {@code void}, and reference) are represented by {@link Class} objects. 67 * (For ease of exposition, we treat {@code void} as if it were a type. 68 * In fact, it denotes the absence of a return type.) 69 * <p> 70 * All instances of {@code MethodType} are immutable. 71 * Two instances are completely interchangeable if they compare equal. 72 * Equality depends on pairwise correspondence of the return and parameter types and on nothing else. 73 * <p> 74 * This type can be created only by factory methods. 75 * All factory methods may cache values, though caching is not guaranteed. 76 * Some factory methods are static, while others are virtual methods which 77 * modify precursor method types, e.g., by changing a selected parameter. 78 * <p> 79 * Factory methods which operate on groups of parameter types 80 * are systematically presented in two versions, so that both Java arrays and 81 * Java lists can be used to work with groups of parameter types. 82 * The query methods {@code parameterArray} and {@code parameterList} 83 * also provide a choice between arrays and lists. 84 * <p> 85 * {@code MethodType} objects are sometimes derived from bytecode instructions 86 * such as {@code invokedynamic}, specifically from the type descriptor strings associated 87 * with the instructions in a class file's constant pool. 88 * <p> 89 * Like classes and strings, method types can also be represented directly 90 * in a class file's constant pool as constants. 91 * A method type may be loaded by an {@code ldc} instruction which refers 92 * to a suitable {@code CONSTANT_MethodType} constant pool entry. 93 * The entry refers to a {@code CONSTANT_Utf8} spelling for the descriptor string. 94 * (For full details on method type constants, see sections {@jvms 95 * 4.4.8} and {@jvms 5.4.3.5} of the Java Virtual Machine 96 * Specification.) 97 * <p> 98 * When the JVM materializes a {@code MethodType} from a descriptor string, 99 * all classes named in the descriptor must be accessible, and will be loaded. 100 * (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.) 101 * This loading may occur at any time before the {@code MethodType} object is first derived. 102 * @author John Rose, JSR 292 EG 103 * @since 1.7 104 */ 105 public final 106 class MethodType 107 implements Constable, 108 TypeDescriptor.OfMethod<Class<?>, MethodType>, 109 java.io.Serializable { 110 @java.io.Serial 111 private static final long serialVersionUID = 292L; // {rtype, {ptype...}} 112 113 // The rtype and ptypes fields define the structural identity of the method type: 114 private final @Stable Class<?> rtype; 115 private final @Stable Class<?>[] ptypes; 116 117 // The remaining fields are caches of various sorts: 118 private @Stable MethodTypeForm form; // erased form, plus cached data about primitives 119 private @Stable MethodType wrapAlt; // alternative wrapped/unwrapped version 120 private @Stable Invokers invokers; // cache of handy higher-order adapters 121 private @Stable String methodDescriptor; // cache for toMethodDescriptorString 122 123 /** 124 * Constructor that performs no copying or validation. 125 * Should only be called from the factory method makeImpl 126 */ 127 private MethodType(Class<?> rtype, Class<?>[] ptypes) { 128 this.rtype = rtype; 129 this.ptypes = ptypes; 130 } 131 132 /*trusted*/ MethodTypeForm form() { return form; } 133 /*trusted*/ Class<?> rtype() { return rtype; } 134 /*trusted*/ Class<?>[] ptypes() { return ptypes; } 135 136 void setForm(MethodTypeForm f) { form = f; } 137 138 /** This number, mandated by the JVM spec as 255, 139 * is the maximum number of <em>slots</em> 140 * that any Java method can receive in its argument list. 141 * It limits both JVM signatures and method type objects. 142 * The longest possible invocation will look like 143 * {@code staticMethod(arg1, arg2, ..., arg255)} or 144 * {@code x.virtualMethod(arg1, arg2, ..., arg254)}. 145 */ 146 /*non-public*/ 147 static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec. 148 149 /** This number is the maximum arity of a method handle, 254. 150 * It is derived from the absolute JVM-imposed arity by subtracting one, 151 * which is the slot occupied by the method handle itself at the 152 * beginning of the argument list used to invoke the method handle. 153 * The longest possible invocation will look like 154 * {@code mh.invoke(arg1, arg2, ..., arg254)}. 155 */ 156 // Issue: Should we allow MH.invokeWithArguments to go to the full 255? 157 /*non-public*/ 158 static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver 159 160 /** This number is the maximum arity of a method handle invoker, 253. 161 * It is derived from the absolute JVM-imposed arity by subtracting two, 162 * which are the slots occupied by invoke method handle, and the 163 * target method handle, which are both at the beginning of the argument 164 * list used to invoke the target method handle. 165 * The longest possible invocation will look like 166 * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}. 167 */ 168 /*non-public*/ 169 static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker 170 171 private static void checkRtype(Class<?> rtype) { 172 Objects.requireNonNull(rtype); 173 } 174 private static void checkPtype(Class<?> ptype) { 175 Objects.requireNonNull(ptype); 176 if (ptype == void.class) 177 throw newIllegalArgumentException("parameter type cannot be void"); 178 } 179 /** Return number of extra slots (count of long/double args). */ 180 private static int checkPtypes(Class<?>[] ptypes) { 181 int slots = 0; 182 for (Class<?> ptype : ptypes) { 183 checkPtype(ptype); 184 if (ptype == double.class || ptype == long.class) { 185 slots++; 186 } 187 } 188 checkSlotCount(ptypes.length + slots); 189 return slots; 190 } 191 192 static { 193 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work: 194 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0); 195 } 196 static void checkSlotCount(int count) { 197 if ((count & MAX_JVM_ARITY) != count) 198 throw newIllegalArgumentException("bad parameter count "+count); 199 } 200 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) { 201 if (num instanceof Integer) num = "bad index: "+num; 202 return new IndexOutOfBoundsException(num.toString()); 203 } 204 205 static final ConcurrentWeakInternSet<MethodType> internTable = new ConcurrentWeakInternSet<>(); 206 207 static final Class<?>[] NO_PTYPES = {}; 208 209 /** 210 * Finds or creates an instance of the given method type. 211 * @param rtype the return type 212 * @param ptypes the parameter types 213 * @return a method type with the given components 214 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null 215 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class} 216 */ 217 public static MethodType methodType(Class<?> rtype, Class<?>[] ptypes) { 218 return makeImpl(rtype, ptypes, false); 219 } 220 221 /** 222 * Finds or creates a method type with the given components. 223 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 224 * @param rtype the return type 225 * @param ptypes the parameter types 226 * @return a method type with the given components 227 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null 228 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class} 229 */ 230 public static MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) { 231 boolean notrust = false; // random List impl. could return evil ptypes array 232 return makeImpl(rtype, listToArray(ptypes), notrust); 233 } 234 235 private static Class<?>[] listToArray(List<Class<?>> ptypes) { 236 // sanity check the size before the toArray call, since size might be huge 237 checkSlotCount(ptypes.size()); 238 return ptypes.toArray(NO_PTYPES); 239 } 240 241 /** 242 * Finds or creates a method type with the given components. 243 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 244 * The leading parameter type is prepended to the remaining array. 245 * @param rtype the return type 246 * @param ptype0 the first parameter type 247 * @param ptypes the remaining parameter types 248 * @return a method type with the given components 249 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null 250 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class} 251 */ 252 public static MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) { 253 Class<?>[] ptypes1 = new Class<?>[1+ptypes.length]; 254 ptypes1[0] = ptype0; 255 System.arraycopy(ptypes, 0, ptypes1, 1, ptypes.length); 256 return makeImpl(rtype, ptypes1, true); 257 } 258 259 /** 260 * Finds or creates a method type with the given components. 261 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 262 * The resulting method has no parameter types. 263 * @param rtype the return type 264 * @return a method type with the given return value 265 * @throws NullPointerException if {@code rtype} is null 266 */ 267 public static MethodType methodType(Class<?> rtype) { 268 return makeImpl(rtype, NO_PTYPES, true); 269 } 270 271 /** 272 * Finds or creates a method type with the given components. 273 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 274 * The resulting method has the single given parameter type. 275 * @param rtype the return type 276 * @param ptype0 the parameter type 277 * @return a method type with the given return value and parameter type 278 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null 279 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class} 280 */ 281 public static MethodType methodType(Class<?> rtype, Class<?> ptype0) { 282 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true); 283 } 284 285 /** 286 * Finds or creates a method type with the given components. 287 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 288 * The resulting method has the same parameter types as {@code ptypes}, 289 * and the specified return type. 290 * @param rtype the return type 291 * @param ptypes the method type which supplies the parameter types 292 * @return a method type with the given components 293 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null 294 */ 295 public static 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*/ 307 static 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(rtype, ptypes); 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 MethodType.checkRtype(rtype); 318 if (trusted) { 319 MethodType.checkPtypes(ptypes); 320 mt = primordialMT; 321 } else { 322 // Make defensive copy then validate 323 ptypes = Arrays.copyOf(ptypes, ptypes.length); 324 MethodType.checkPtypes(ptypes); 325 mt = new MethodType(rtype, ptypes); 326 } 327 mt.form = MethodTypeForm.findForm(mt); 328 return internTable.add(mt); 329 } 330 private static final @Stable MethodType[] objectOnlyTypes = new MethodType[20]; 331 332 /** 333 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array. 334 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 335 * All parameters and the return type will be {@code Object}, 336 * except the final array parameter if any, which will be {@code Object[]}. 337 * @param objectArgCount number of parameters (excluding the final array parameter if any) 338 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]} 339 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments 340 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true) 341 * @see #genericMethodType(int) 342 */ 343 public static MethodType genericMethodType(int objectArgCount, boolean finalArray) { 344 MethodType mt; 345 checkSlotCount(objectArgCount); 346 int ivarargs = (!finalArray ? 0 : 1); 347 int ootIndex = objectArgCount*2 + ivarargs; 348 if (ootIndex < objectOnlyTypes.length) { 349 mt = objectOnlyTypes[ootIndex]; 350 if (mt != null) return mt; 351 } 352 Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs]; 353 Arrays.fill(ptypes, Object.class); 354 if (ivarargs != 0) ptypes[objectArgCount] = Object[].class; 355 mt = makeImpl(Object.class, ptypes, true); 356 if (ootIndex < objectOnlyTypes.length) { 357 objectOnlyTypes[ootIndex] = mt; // cache it here also! 358 } 359 return mt; 360 } 361 362 /** 363 * Finds or creates a method type whose components are all {@code Object}. 364 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 365 * All parameters and the return type will be Object. 366 * @param objectArgCount number of parameters 367 * @return a generally applicable method type, for all calls of the given argument count 368 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 369 * @see #genericMethodType(int, boolean) 370 */ 371 public static MethodType genericMethodType(int objectArgCount) { 372 return genericMethodType(objectArgCount, false); 373 } 374 375 /** 376 * Finds or creates a method type with a single different parameter type. 377 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 378 * @param num the index (zero-based) of the parameter type to change 379 * @param nptype a new parameter type to replace the old one with 380 * @return the same type, except with the selected parameter changed 381 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()} 382 * @throws IllegalArgumentException if {@code nptype} is {@code void.class} 383 * @throws NullPointerException if {@code nptype} is null 384 */ 385 public MethodType changeParameterType(int num, Class<?> nptype) { 386 if (parameterType(num) == nptype) return this; 387 checkPtype(nptype); 388 Class<?>[] nptypes = ptypes.clone(); 389 nptypes[num] = nptype; 390 return makeImpl(rtype, nptypes, true); 391 } 392 393 /** 394 * Finds or creates a method type with additional parameter types. 395 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 396 * @param num the position (zero-based) of the inserted parameter type(s) 397 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 398 * @return the same type, except with the selected parameter(s) inserted 399 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()} 400 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 401 * or if the resulting method type would have more than 255 parameter slots 402 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 403 */ 404 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) { 405 int len = ptypes.length; 406 if (num < 0 || num > len) 407 throw newIndexOutOfBoundsException(num); 408 int ins = checkPtypes(ptypesToInsert); 409 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins); 410 int ilen = ptypesToInsert.length; 411 if (ilen == 0) return this; 412 Class<?>[] nptypes = new Class<?>[len + ilen]; 413 if (num > 0) { 414 System.arraycopy(ptypes, 0, nptypes, 0, num); 415 } 416 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen); 417 if (num < len) { 418 System.arraycopy(ptypes, num, nptypes, num+ilen, len-num); 419 } 420 return makeImpl(rtype, nptypes, true); 421 } 422 423 /** 424 * Finds or creates a method type with additional parameter types. 425 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 426 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list 427 * @return the same type, except with the selected parameter(s) appended 428 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 429 * or if the resulting method type would have more than 255 parameter slots 430 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 431 */ 432 public MethodType appendParameterTypes(Class<?>... ptypesToInsert) { 433 return insertParameterTypes(parameterCount(), ptypesToInsert); 434 } 435 436 /** 437 * Finds or creates a method type with additional parameter types. 438 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 439 * @param num the position (zero-based) of the inserted parameter type(s) 440 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 441 * @return the same type, except with the selected parameter(s) inserted 442 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()} 443 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 444 * or if the resulting method type would have more than 255 parameter slots 445 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 446 */ 447 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) { 448 return insertParameterTypes(num, listToArray(ptypesToInsert)); 449 } 450 451 /** 452 * Finds or creates a method type with additional parameter types. 453 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 454 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list 455 * @return the same type, except with the selected parameter(s) appended 456 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 457 * or if the resulting method type would have more than 255 parameter slots 458 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 459 */ 460 public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) { 461 return insertParameterTypes(parameterCount(), ptypesToInsert); 462 } 463 464 /** 465 * Finds or creates a method type with modified parameter types. 466 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 467 * @param start the position (zero-based) of the first replaced parameter type(s) 468 * @param end the position (zero-based) after the last replaced parameter type(s) 469 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 470 * @return the same type, except with the selected parameter(s) replaced 471 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()} 472 * or if {@code end} is negative or greater than {@code parameterCount()} 473 * or if {@code start} is greater than {@code end} 474 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 475 * or if the resulting method type would have more than 255 parameter slots 476 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 477 */ 478 /*non-public*/ 479 MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) { 480 if (start == end) 481 return insertParameterTypes(start, ptypesToInsert); 482 int len = ptypes.length; 483 if (!(0 <= start && start <= end && end <= len)) 484 throw newIndexOutOfBoundsException("start="+start+" end="+end); 485 int ilen = ptypesToInsert.length; 486 if (ilen == 0) 487 return dropParameterTypes(start, end); 488 return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert); 489 } 490 491 /** Replace the last arrayLength parameter types with the component type of arrayType. 492 * @param arrayType any array type 493 * @param pos position at which to spread 494 * @param arrayLength the number of parameter types to change 495 * @return the resulting type 496 */ 497 /*non-public*/ 498 MethodType asSpreaderType(Class<?> arrayType, int pos, int arrayLength) { 499 assert(parameterCount() >= arrayLength); 500 int spreadPos = pos; 501 if (arrayLength == 0) return this; // nothing to change 502 if (arrayType == Object[].class) { 503 if (isGeneric()) return this; // nothing to change 504 if (spreadPos == 0) { 505 // no leading arguments to preserve; go generic 506 MethodType res = genericMethodType(arrayLength); 507 if (rtype != Object.class) { 508 res = res.changeReturnType(rtype); 509 } 510 return res; 511 } 512 } 513 Class<?> elemType = arrayType.getComponentType(); 514 assert(elemType != null); 515 for (int i = spreadPos; i < spreadPos + arrayLength; i++) { 516 if (ptypes[i] != elemType) { 517 Class<?>[] fixedPtypes = ptypes.clone(); 518 Arrays.fill(fixedPtypes, i, spreadPos + arrayLength, elemType); 519 return methodType(rtype, fixedPtypes); 520 } 521 } 522 return this; // arguments check out; no change 523 } 524 525 /** Return the leading parameter type, which must exist and be a reference. 526 * @return the leading parameter type, after error checks 527 */ 528 /*non-public*/ 529 Class<?> leadingReferenceParameter() { 530 Class<?> ptype; 531 if (ptypes.length == 0 || 532 (ptype = ptypes[0]).isPrimitive()) 533 throw newIllegalArgumentException("no leading reference parameter"); 534 return ptype; 535 } 536 537 /** Delete the last parameter type and replace it with arrayLength copies of the component type of arrayType. 538 * @param arrayType any array type 539 * @param pos position at which to insert parameters 540 * @param arrayLength the number of parameter types to insert 541 * @return the resulting type 542 */ 543 /*non-public*/ 544 MethodType asCollectorType(Class<?> arrayType, int pos, int arrayLength) { 545 assert(parameterCount() >= 1); 546 assert(pos < ptypes.length); 547 assert(ptypes[pos].isAssignableFrom(arrayType)); 548 MethodType res; 549 if (arrayType == Object[].class) { 550 res = genericMethodType(arrayLength); 551 if (rtype != Object.class) { 552 res = res.changeReturnType(rtype); 553 } 554 } else { 555 Class<?> elemType = arrayType.getComponentType(); 556 assert(elemType != null); 557 res = methodType(rtype, Collections.nCopies(arrayLength, elemType)); 558 } 559 if (ptypes.length == 1) { 560 return res; 561 } else { 562 // insert after (if need be), then before 563 if (pos < ptypes.length - 1) { 564 res = res.insertParameterTypes(arrayLength, Arrays.copyOfRange(ptypes, pos + 1, ptypes.length)); 565 } 566 return res.insertParameterTypes(0, Arrays.copyOf(ptypes, pos)); 567 } 568 } 569 570 /** 571 * Finds or creates a method type with some parameter types omitted. 572 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 573 * @param start the index (zero-based) of the first parameter type to remove 574 * @param end the index (greater than {@code start}) of the first parameter type after not to remove 575 * @return the same type, except with the selected parameter(s) removed 576 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()} 577 * or if {@code end} is negative or greater than {@code parameterCount()} 578 * or if {@code start} is greater than {@code end} 579 */ 580 public MethodType dropParameterTypes(int start, int end) { 581 int len = ptypes.length; 582 if (!(0 <= start && start <= end && end <= len)) 583 throw newIndexOutOfBoundsException("start="+start+" end="+end); 584 if (start == end) return this; 585 Class<?>[] nptypes; 586 if (start == 0) { 587 if (end == len) { 588 // drop all parameters 589 nptypes = NO_PTYPES; 590 } else { 591 // drop initial parameter(s) 592 nptypes = Arrays.copyOfRange(ptypes, end, len); 593 } 594 } else { 595 if (end == len) { 596 // drop trailing parameter(s) 597 nptypes = Arrays.copyOfRange(ptypes, 0, start); 598 } else { 599 int tail = len - end; 600 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail); 601 System.arraycopy(ptypes, end, nptypes, start, tail); 602 } 603 } 604 return makeImpl(rtype, nptypes, true); 605 } 606 607 /** 608 * Finds or creates a method type with a different return type. 609 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 610 * @param nrtype a return parameter type to replace the old one with 611 * @return the same type, except with the return type change 612 * @throws NullPointerException if {@code nrtype} is null 613 */ 614 public MethodType changeReturnType(Class<?> nrtype) { 615 if (returnType() == nrtype) return this; 616 return makeImpl(nrtype, ptypes, true); 617 } 618 619 /** 620 * Reports if this type contains a primitive argument or return value. 621 * The return type {@code void} counts as a primitive. 622 * @return true if any of the types are primitives 623 */ 624 public boolean hasPrimitives() { 625 return form.hasPrimitives(); 626 } 627 628 /** 629 * Reports if this type contains a wrapper argument or return value. 630 * Wrappers are types which box primitive values, such as {@link Integer}. 631 * The reference type {@code java.lang.Void} counts as a wrapper, 632 * if it occurs as a return type. 633 * @return true if any of the types are wrappers 634 */ 635 public boolean hasWrappers() { 636 return unwrap() != this; 637 } 638 639 /** 640 * Erases all reference types to {@code Object}. 641 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 642 * All primitive types (including {@code void}) will remain unchanged. 643 * @return a version of the original type with all reference types replaced 644 */ 645 public MethodType erase() { 646 return form.erasedType(); 647 } 648 649 /** 650 * Erases all reference types to {@code Object}, and all subword types to {@code int}. 651 * This is the reduced type polymorphism used by private methods 652 * such as {@link MethodHandle#invokeBasic invokeBasic}. 653 * @return a version of the original type with all reference and subword types replaced 654 */ 655 /*non-public*/ 656 MethodType basicType() { 657 return form.basicType(); 658 } 659 660 private static final @Stable Class<?>[] METHOD_HANDLE_ARRAY 661 = new Class<?>[] { MethodHandle.class }; 662 663 /** 664 * @return a version of the original type with MethodHandle prepended as the first argument 665 */ 666 /*non-public*/ 667 MethodType invokerType() { 668 return insertParameterTypes(0, METHOD_HANDLE_ARRAY); 669 } 670 671 /** 672 * Converts all types, both reference and primitive, to {@code Object}. 673 * Convenience method for {@link #genericMethodType(int) genericMethodType}. 674 * The expression {@code type.wrap().erase()} produces the same value 675 * as {@code type.generic()}. 676 * @return a version of the original type with all types replaced 677 */ 678 public MethodType generic() { 679 return genericMethodType(parameterCount()); 680 } 681 682 /*non-public*/ 683 boolean isGeneric() { 684 return this == erase() && !hasPrimitives(); 685 } 686 687 /** 688 * Converts all primitive types to their corresponding wrapper types. 689 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 690 * All reference types (including wrapper types) will remain unchanged. 691 * A {@code void} return type is changed to the type {@code java.lang.Void}. 692 * The expression {@code type.wrap().erase()} produces the same value 693 * as {@code type.generic()}. 694 * @return a version of the original type with all primitive types replaced 695 */ 696 public MethodType wrap() { 697 return hasPrimitives() ? wrapWithPrims(this) : this; 698 } 699 700 /** 701 * Converts all wrapper types to their corresponding primitive types. 702 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 703 * All primitive types (including {@code void}) will remain unchanged. 704 * A return type of {@code java.lang.Void} is changed to {@code void}. 705 * @return a version of the original type with all wrapper types replaced 706 */ 707 public MethodType unwrap() { 708 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this); 709 return unwrapWithNoPrims(noprims); 710 } 711 712 private static MethodType wrapWithPrims(MethodType pt) { 713 assert(pt.hasPrimitives()); 714 MethodType wt = pt.wrapAlt; 715 if (wt == null) { 716 // fill in lazily 717 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP, MethodTypeForm.WRAP); 718 assert(wt != null); 719 pt.wrapAlt = wt; 720 } 721 return wt; 722 } 723 724 private static MethodType unwrapWithNoPrims(MethodType wt) { 725 assert(!wt.hasPrimitives()); 726 MethodType uwt = wt.wrapAlt; 727 if (uwt == null) { 728 // fill in lazily 729 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP, MethodTypeForm.UNWRAP); 730 if (uwt == null) 731 uwt = wt; // type has no wrappers or prims at all 732 wt.wrapAlt = uwt; 733 } 734 return uwt; 735 } 736 737 /** 738 * Returns the parameter type at the specified index, within this method type. 739 * @param num the index (zero-based) of the desired parameter type 740 * @return the selected parameter type 741 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()} 742 */ 743 public Class<?> parameterType(int num) { 744 return ptypes[num]; 745 } 746 /** 747 * Returns the number of parameter types in this method type. 748 * @return the number of parameter types 749 */ 750 public int parameterCount() { 751 return ptypes.length; 752 } 753 /** 754 * Returns the return type of this method type. 755 * @return the return type 756 */ 757 public Class<?> returnType() { 758 return rtype; 759 } 760 761 /** 762 * Presents the parameter types as a list (a convenience method). 763 * The list will be immutable. 764 * @return the parameter types (as an immutable list) 765 */ 766 public List<Class<?>> parameterList() { 767 return Collections.unmodifiableList(Arrays.asList(ptypes.clone())); 768 } 769 770 /** 771 * Returns the last parameter type of this method type. 772 * If this type has no parameters, the sentinel value 773 * {@code void.class} is returned instead. 774 * @apiNote 775 * <p> 776 * The sentinel value is chosen so that reflective queries can be 777 * made directly against the result value. 778 * The sentinel value cannot be confused with a real parameter, 779 * since {@code void} is never acceptable as a parameter type. 780 * For variable arity invocation modes, the expression 781 * {@link Class#getComponentType lastParameterType().getComponentType()} 782 * is useful to query the type of the "varargs" parameter. 783 * @return the last parameter type if any, else {@code void.class} 784 * @since 10 785 */ 786 public Class<?> lastParameterType() { 787 int len = ptypes.length; 788 return len == 0 ? void.class : ptypes[len-1]; 789 } 790 791 /** 792 * Presents the parameter types as an array (a convenience method). 793 * Changes to the array will not result in changes to the type. 794 * @return the parameter types (as a fresh copy if necessary) 795 */ 796 public Class<?>[] parameterArray() { 797 return ptypes.clone(); 798 } 799 800 /** 801 * Compares the specified object with this type for equality. 802 * That is, it returns {@code true} if and only if the specified object 803 * is also a method type with exactly the same parameters and return type. 804 * @param x object to compare 805 * @see Object#equals(Object) 806 */ 807 // This implementation may also return true if x is a WeakEntry containing 808 // a method type that is equal to this. This is an internal implementation 809 // detail to allow for faster method type lookups. 810 // See ConcurrentWeakInternSet.WeakEntry#equals(Object) 811 @Override 812 public boolean equals(Object x) { 813 if (this == x) { 814 return true; 815 } 816 if (x instanceof MethodType) { 817 return equals((MethodType)x); 818 } 819 if (x instanceof ConcurrentWeakInternSet.WeakEntry) { 820 Object o = ((ConcurrentWeakInternSet.WeakEntry)x).get(); 821 if (o instanceof MethodType) { 822 return equals((MethodType)o); 823 } 824 } 825 return false; 826 } 827 828 private boolean equals(MethodType that) { 829 return this.rtype == that.rtype 830 && Arrays.equals(this.ptypes, that.ptypes); 831 } 832 833 /** 834 * Returns the hash code value for this method type. 835 * It is defined to be the same as the hashcode of a List 836 * whose elements are the return type followed by the 837 * parameter types. 838 * @return the hash code value for this method type 839 * @see Object#hashCode() 840 * @see #equals(Object) 841 * @see List#hashCode() 842 */ 843 @Override 844 public int hashCode() { 845 int hashCode = 31 + rtype.hashCode(); 846 for (Class<?> ptype : ptypes) 847 hashCode = 31 * hashCode + ptype.hashCode(); 848 return hashCode; 849 } 850 851 /** 852 * Returns a string representation of the method type, 853 * of the form {@code "(PT0,PT1...)RT"}. 854 * The string representation of a method type is a 855 * parenthesis enclosed, comma separated list of type names, 856 * followed immediately by the return type. 857 * <p> 858 * Each type is represented by its 859 * {@link java.lang.Class#getSimpleName simple name}. 860 */ 861 @Override 862 public String toString() { 863 StringJoiner sj = new StringJoiner(",", "(", 864 ")" + rtype.getSimpleName()); 865 for (int i = 0; i < ptypes.length; i++) { 866 sj.add(ptypes[i].getSimpleName()); 867 } 868 return sj.toString(); 869 } 870 871 /** True if my parameter list is effectively identical to the given full list, 872 * after skipping the given number of my own initial parameters. 873 * In other words, after disregarding {@code skipPos} parameters, 874 * my remaining parameter list is no longer than the {@code fullList}, and 875 * is equal to the same-length initial sublist of {@code fullList}. 876 */ 877 /*non-public*/ 878 boolean effectivelyIdenticalParameters(int skipPos, List<Class<?>> fullList) { 879 int myLen = ptypes.length, fullLen = fullList.size(); 880 if (skipPos > myLen || myLen - skipPos > fullLen) 881 return false; 882 List<Class<?>> myList = Arrays.asList(ptypes); 883 if (skipPos != 0) { 884 myList = myList.subList(skipPos, myLen); 885 myLen -= skipPos; 886 } 887 if (fullLen == myLen) 888 return myList.equals(fullList); 889 else 890 return myList.equals(fullList.subList(0, myLen)); 891 } 892 893 /** True if the old return type can always be viewed (w/o casting) under new return type, 894 * and the new parameters can be viewed (w/o casting) under the old parameter types. 895 */ 896 /*non-public*/ 897 boolean isViewableAs(MethodType newType, boolean keepInterfaces) { 898 if (!VerifyType.isNullConversion(returnType(), newType.returnType(), keepInterfaces)) 899 return false; 900 if (form == newType.form && form.erasedType == this) 901 return true; // my reference parameters are all Object 902 if (ptypes == newType.ptypes) 903 return true; 904 int argc = parameterCount(); 905 if (argc != newType.parameterCount()) 906 return false; 907 for (int i = 0; i < argc; i++) { 908 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i), keepInterfaces)) 909 return false; 910 } 911 return true; 912 } 913 /*non-public*/ 914 boolean isConvertibleTo(MethodType newType) { 915 MethodTypeForm oldForm = this.form(); 916 MethodTypeForm newForm = newType.form(); 917 if (oldForm == newForm) 918 // same parameter count, same primitive/object mix 919 return true; 920 if (!canConvert(returnType(), newType.returnType())) 921 return false; 922 Class<?>[] srcTypes = newType.ptypes; 923 Class<?>[] dstTypes = ptypes; 924 if (srcTypes == dstTypes) 925 return true; 926 int argc; 927 if ((argc = srcTypes.length) != dstTypes.length) 928 return false; 929 if (argc <= 1) { 930 if (argc == 1 && !canConvert(srcTypes[0], dstTypes[0])) 931 return false; 932 return true; 933 } 934 if ((!oldForm.hasPrimitives() && oldForm.erasedType == this) || 935 (!newForm.hasPrimitives() && newForm.erasedType == newType)) { 936 // Somewhat complicated test to avoid a loop of 2 or more trips. 937 // If either type has only Object parameters, we know we can convert. 938 assert(canConvertParameters(srcTypes, dstTypes)); 939 return true; 940 } 941 return canConvertParameters(srcTypes, dstTypes); 942 } 943 944 /** Returns true if MHs.explicitCastArguments produces the same result as MH.asType. 945 * If the type conversion is impossible for either, the result should be false. 946 */ 947 /*non-public*/ 948 boolean explicitCastEquivalentToAsType(MethodType newType) { 949 if (this == newType) return true; 950 if (!explicitCastEquivalentToAsType(rtype, newType.rtype)) { 951 return false; 952 } 953 Class<?>[] srcTypes = newType.ptypes; 954 Class<?>[] dstTypes = ptypes; 955 if (dstTypes == srcTypes) { 956 return true; 957 } 958 assert(dstTypes.length == srcTypes.length); 959 for (int i = 0; i < dstTypes.length; i++) { 960 if (!explicitCastEquivalentToAsType(srcTypes[i], dstTypes[i])) { 961 return false; 962 } 963 } 964 return true; 965 } 966 967 /** Reports true if the src can be converted to the dst, by both asType and MHs.eCE, 968 * and with the same effect. 969 * MHs.eCA has the following "upgrades" to MH.asType: 970 * 1. interfaces are unchecked (that is, treated as if aliased to Object) 971 * Therefore, {@code Object->CharSequence} is possible in both cases but has different semantics 972 * 2. the full matrix of primitive-to-primitive conversions is supported 973 * Narrowing like {@code long->byte} and basic-typing like {@code boolean->int} 974 * are not supported by asType, but anything supported by asType is equivalent 975 * with MHs.eCE. 976 * 3a. unboxing conversions can be followed by the full matrix of primitive conversions 977 * 3b. unboxing of null is permitted (creates a zero primitive value) 978 * Other than interfaces, reference-to-reference conversions are the same. 979 * Boxing primitives to references is the same for both operators. 980 */ 981 private static boolean explicitCastEquivalentToAsType(Class<?> src, Class<?> dst) { 982 if (src == dst || dst == Object.class || dst == void.class) return true; 983 if (src.isPrimitive()) { 984 // Could be a prim/prim conversion, where casting is a strict superset. 985 // Or a boxing conversion, which is always to an exact wrapper class. 986 return canConvert(src, dst); 987 } else if (dst.isPrimitive()) { 988 // Unboxing behavior is different between MHs.eCA & MH.asType (see 3b). 989 return false; 990 } else { 991 // R->R always works, but we have to avoid a check-cast to an interface. 992 return !dst.isInterface() || dst.isAssignableFrom(src); 993 } 994 } 995 996 private boolean canConvertParameters(Class<?>[] srcTypes, Class<?>[] dstTypes) { 997 for (int i = 0; i < srcTypes.length; i++) { 998 if (!canConvert(srcTypes[i], dstTypes[i])) { 999 return false; 1000 } 1001 } 1002 return true; 1003 } 1004 1005 /*non-public*/ 1006 static boolean canConvert(Class<?> src, Class<?> dst) { 1007 // short-circuit a few cases: 1008 if (src == dst || src == Object.class || dst == Object.class) return true; 1009 // the remainder of this logic is documented in MethodHandle.asType 1010 if (src.isPrimitive()) { 1011 // can force void to an explicit null, a la reflect.Method.invoke 1012 // can also force void to a primitive zero, by analogy 1013 if (src == void.class) return true; //or !dst.isPrimitive()? 1014 Wrapper sw = Wrapper.forPrimitiveType(src); 1015 if (dst.isPrimitive()) { 1016 // P->P must widen 1017 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw); 1018 } else { 1019 // P->R must box and widen 1020 return dst.isAssignableFrom(sw.wrapperType()); 1021 } 1022 } else if (dst.isPrimitive()) { 1023 // any value can be dropped 1024 if (dst == void.class) return true; 1025 Wrapper dw = Wrapper.forPrimitiveType(dst); 1026 // R->P must be able to unbox (from a dynamically chosen type) and widen 1027 // For example: 1028 // Byte/Number/Comparable/Object -> dw:Byte -> byte. 1029 // Character/Comparable/Object -> dw:Character -> char 1030 // Boolean/Comparable/Object -> dw:Boolean -> boolean 1031 // This means that dw must be cast-compatible with src. 1032 if (src.isAssignableFrom(dw.wrapperType())) { 1033 return true; 1034 } 1035 // The above does not work if the source reference is strongly typed 1036 // to a wrapper whose primitive must be widened. For example: 1037 // Byte -> unbox:byte -> short/int/long/float/double 1038 // Character -> unbox:char -> int/long/float/double 1039 if (Wrapper.isWrapperType(src) && 1040 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) { 1041 // can unbox from src and then widen to dst 1042 return true; 1043 } 1044 // We have already covered cases which arise due to runtime unboxing 1045 // of a reference type which covers several wrapper types: 1046 // Object -> cast:Integer -> unbox:int -> long/float/double 1047 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double 1048 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a 1049 // subclass of Number which wraps a value that can convert to char. 1050 // Since there is none, we don't need an extra check here to cover char or boolean. 1051 return false; 1052 } else { 1053 // R->R always works, since null is always valid dynamically 1054 return true; 1055 } 1056 } 1057 1058 /// Queries which have to do with the bytecode architecture 1059 1060 /** Reports the number of JVM stack slots required to invoke a method 1061 * of this type. Note that (for historical reasons) the JVM requires 1062 * a second stack slot to pass long and double arguments. 1063 * So this method returns {@link #parameterCount() parameterCount} plus the 1064 * number of long and double parameters (if any). 1065 * <p> 1066 * This method is included for the benefit of applications that must 1067 * generate bytecodes that process method handles and invokedynamic. 1068 * @return the number of JVM stack slots for this type's parameters 1069 */ 1070 /*non-public*/ 1071 int parameterSlotCount() { 1072 return form.parameterSlotCount(); 1073 } 1074 1075 /*non-public*/ 1076 Invokers invokers() { 1077 Invokers inv = invokers; 1078 if (inv != null) return inv; 1079 invokers = inv = new Invokers(this); 1080 return inv; 1081 } 1082 1083 /** 1084 * Finds or creates an instance of a method type, given the spelling of its bytecode descriptor. 1085 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 1086 * Any class or interface name embedded in the descriptor string will be 1087 * resolved by the given loader (or if it is null, on the system class loader). 1088 * <p> 1089 * Note that it is possible to encounter method types which cannot be 1090 * constructed by this method, because their component types are 1091 * not all reachable from a common class loader. 1092 * <p> 1093 * This method is included for the benefit of applications that must 1094 * generate bytecodes that process method handles and {@code invokedynamic}. 1095 * @param descriptor a bytecode-level type descriptor string "(T...)T" 1096 * @param loader the class loader in which to look up the types 1097 * @return a method type matching the bytecode-level type descriptor 1098 * @throws NullPointerException if the string is null 1099 * @throws IllegalArgumentException if the string is not well-formed 1100 * @throws TypeNotPresentException if a named type cannot be found 1101 * @throws SecurityException if the security manager is present and 1102 * {@code loader} is {@code null} and the caller does not have the 1103 * {@link RuntimePermission}{@code ("getClassLoader")} 1104 */ 1105 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader) 1106 throws IllegalArgumentException, TypeNotPresentException 1107 { 1108 if (loader == null) { 1109 SecurityManager sm = System.getSecurityManager(); 1110 if (sm != null) { 1111 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION); 1112 } 1113 } 1114 return fromDescriptor(descriptor, 1115 (loader == null) ? ClassLoader.getSystemClassLoader() : loader); 1116 } 1117 1118 /** 1119 * Same as {@link #fromMethodDescriptorString(String, ClassLoader)}, but 1120 * {@code null} ClassLoader means the bootstrap loader is used here. 1121 * <p> 1122 * IMPORTANT: This method is preferable for JDK internal use as it more 1123 * correctly interprets {@code null} ClassLoader than 1124 * {@link #fromMethodDescriptorString(String, ClassLoader)}. 1125 * Use of this method also avoids early initialization issues when system 1126 * ClassLoader is not initialized yet. 1127 */ 1128 static MethodType fromDescriptor(String descriptor, ClassLoader loader) 1129 throws IllegalArgumentException, TypeNotPresentException 1130 { 1131 if (!descriptor.startsWith("(") || // also generates NPE if needed 1132 descriptor.indexOf(')') < 0 || 1133 descriptor.indexOf('.') >= 0) 1134 throw newIllegalArgumentException("not a method descriptor: "+descriptor); 1135 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader); 1136 Class<?> rtype = types.remove(types.size() - 1); 1137 Class<?>[] ptypes = listToArray(types); 1138 return makeImpl(rtype, ptypes, true); 1139 } 1140 1141 /** 1142 * Produces a bytecode descriptor representation of the method type. 1143 * <p> 1144 * Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}. 1145 * Two distinct classes which share a common name but have different class loaders 1146 * will appear identical when viewed within descriptor strings. 1147 * <p> 1148 * This method is included for the benefit of applications that must 1149 * generate bytecodes that process method handles and {@code invokedynamic}. 1150 * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString}, 1151 * because the latter requires a suitable class loader argument. 1152 * @return the bytecode type descriptor representation 1153 */ 1154 public String toMethodDescriptorString() { 1155 String desc = methodDescriptor; 1156 if (desc == null) { 1157 desc = BytecodeDescriptor.unparseMethod(this.rtype, this.ptypes); 1158 methodDescriptor = desc; 1159 } 1160 return desc; 1161 } 1162 1163 /** 1164 * Return a field type descriptor string for this type 1165 * 1166 * @return the descriptor string 1167 * @jvms 4.3.2 Field Descriptors 1168 * @since 12 1169 */ 1170 @Override 1171 public String descriptorString() { 1172 return toMethodDescriptorString(); 1173 } 1174 1175 /*non-public*/ 1176 static String toFieldDescriptorString(Class<?> cls) { 1177 return BytecodeDescriptor.unparse(cls); 1178 } 1179 1180 /** 1181 * Return a nominal descriptor for this instance, if one can be 1182 * constructed, or an empty {@link Optional} if one cannot be. 1183 * 1184 * @return An {@link Optional} containing the resulting nominal descriptor, 1185 * or an empty {@link Optional} if one cannot be constructed. 1186 * @since 12 1187 */ 1188 @Override 1189 public Optional<MethodTypeDesc> describeConstable() { 1190 try { 1191 return Optional.of(MethodTypeDesc.of(returnType().describeConstable().orElseThrow(), 1192 Stream.of(parameterArray()) 1193 .map(p -> p.describeConstable().orElseThrow()) 1194 .toArray(ClassDesc[]::new))); 1195 } 1196 catch (NoSuchElementException e) { 1197 return Optional.empty(); 1198 } 1199 } 1200 1201 /// Serialization. 1202 1203 /** 1204 * There are no serializable fields for {@code MethodType}. 1205 */ 1206 @java.io.Serial 1207 private static final java.io.ObjectStreamField[] serialPersistentFields = { }; 1208 1209 /** 1210 * Save the {@code MethodType} instance to a stream. 1211 * 1212 * @serialData 1213 * For portability, the serialized format does not refer to named fields. 1214 * Instead, the return type and parameter type arrays are written directly 1215 * from the {@code writeObject} method, using two calls to {@code s.writeObject} 1216 * as follows: 1217 * <blockquote><pre>{@code 1218 s.writeObject(this.returnType()); 1219 s.writeObject(this.parameterArray()); 1220 * }</pre></blockquote> 1221 * <p> 1222 * The deserialized field values are checked as if they were 1223 * provided to the factory method {@link #methodType(Class,Class[]) methodType}. 1224 * For example, null values, or {@code void} parameter types, 1225 * will lead to exceptions during deserialization. 1226 * @param s the stream to write the object to 1227 * @throws java.io.IOException if there is a problem writing the object 1228 */ 1229 @java.io.Serial 1230 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException { 1231 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array 1232 s.writeObject(returnType()); 1233 s.writeObject(parameterArray()); 1234 } 1235 1236 /** 1237 * Reconstitute the {@code MethodType} instance from a stream (that is, 1238 * deserialize it). 1239 * This instance is a scratch object with bogus final fields. 1240 * It provides the parameters to the factory method called by 1241 * {@link #readResolve readResolve}. 1242 * After that call it is discarded. 1243 * @param s the stream to read the object from 1244 * @throws java.io.IOException if there is a problem reading the object 1245 * @throws ClassNotFoundException if one of the component classes cannot be resolved 1246 * @see #readResolve 1247 * @see #writeObject 1248 */ 1249 @java.io.Serial 1250 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException { 1251 // Assign temporary defaults in case this object escapes 1252 MethodType_init(void.class, NO_PTYPES); 1253 1254 s.defaultReadObject(); // requires serialPersistentFields to be an empty array 1255 1256 Class<?> returnType = (Class<?>) s.readObject(); 1257 Class<?>[] parameterArray = (Class<?>[]) s.readObject(); 1258 parameterArray = parameterArray.clone(); // make sure it is unshared 1259 1260 // Assign deserialized values 1261 MethodType_init(returnType, parameterArray); 1262 } 1263 1264 // Initialization of state for deserialization only 1265 private void MethodType_init(Class<?> rtype, Class<?>[] ptypes) { 1266 // In order to communicate these values to readResolve, we must 1267 // store them into the implementation-specific final fields. 1268 checkRtype(rtype); 1269 checkPtypes(ptypes); 1270 UNSAFE.putReference(this, OffsetHolder.rtypeOffset, rtype); 1271 UNSAFE.putReference(this, OffsetHolder.ptypesOffset, ptypes); 1272 } 1273 1274 // Support for resetting final fields while deserializing. Implement Holder 1275 // pattern to make the rarely needed offset calculation lazy. 1276 private static class OffsetHolder { 1277 static final long rtypeOffset 1278 = UNSAFE.objectFieldOffset(MethodType.class, "rtype"); 1279 1280 static final long ptypesOffset 1281 = UNSAFE.objectFieldOffset(MethodType.class, "ptypes"); 1282 } 1283 1284 /** 1285 * Resolves and initializes a {@code MethodType} object 1286 * after serialization. 1287 * @return the fully initialized {@code MethodType} object 1288 */ 1289 @java.io.Serial 1290 private Object readResolve() { 1291 // Do not use a trusted path for deserialization: 1292 // return makeImpl(rtype, ptypes, true); 1293 // Verify all operands, and make sure ptypes is unshared: 1294 try { 1295 return methodType(rtype, ptypes); 1296 } finally { 1297 // Re-assign defaults in case this object escapes 1298 MethodType_init(void.class, NO_PTYPES); 1299 } 1300 } 1301 1302 /** 1303 * Simple implementation of weak concurrent intern set. 1304 * 1305 * @param <T> interned type 1306 */ 1307 private static class ConcurrentWeakInternSet<T> { 1308 1309 private final ConcurrentMap<WeakEntry<T>, WeakEntry<T>> map; 1310 private final ReferenceQueue<T> stale; 1311 1312 public ConcurrentWeakInternSet() { 1313 this.map = new ConcurrentHashMap<>(512); 1314 this.stale = new ReferenceQueue<>(); 1315 } 1316 1317 /** 1318 * Get the existing interned element. 1319 * This method returns null if no element is interned. 1320 * 1321 * @param elem element to look up 1322 * @return the interned element 1323 */ 1324 public T get(T elem) { 1325 if (elem == null) throw new NullPointerException(); 1326 expungeStaleElements(); 1327 1328 WeakEntry<T> value = map.get(elem); 1329 if (value != null) { 1330 T res = value.get(); 1331 if (res != null) { 1332 return res; 1333 } 1334 } 1335 return null; 1336 } 1337 1338 /** 1339 * Interns the element. 1340 * Always returns non-null element, matching the one in the intern set. 1341 * Under the race against another add(), it can return <i>different</i> 1342 * element, if another thread beats us to interning it. 1343 * 1344 * @param elem element to add 1345 * @return element that was actually added 1346 */ 1347 public T add(T elem) { 1348 if (elem == null) throw new NullPointerException(); 1349 1350 // Playing double race here, and so spinloop is required. 1351 // First race is with two concurrent updaters. 1352 // Second race is with GC purging weak ref under our feet. 1353 // Hopefully, we almost always end up with a single pass. 1354 T interned; 1355 WeakEntry<T> e = new WeakEntry<>(elem, stale); 1356 do { 1357 expungeStaleElements(); 1358 WeakEntry<T> exist = map.putIfAbsent(e, e); 1359 interned = (exist == null) ? elem : exist.get(); 1360 } while (interned == null); 1361 return interned; 1362 } 1363 1364 private void expungeStaleElements() { 1365 Reference<? extends T> reference; 1366 while ((reference = stale.poll()) != null) { 1367 map.remove(reference); 1368 } 1369 } 1370 1371 private static class WeakEntry<T> extends WeakReference<T> { 1372 1373 public final int hashcode; 1374 1375 public WeakEntry(T key, ReferenceQueue<T> queue) { 1376 super(key, queue); 1377 hashcode = key.hashCode(); 1378 } 1379 1380 /** 1381 * This implementation returns {@code true} if {@code obj} is another 1382 * {@code WeakEntry} whose referent equals to this referent, or 1383 * if {@code obj} equals to the referent of this. This allows 1384 * lookups to be made without wrapping in a {@code WeakEntry}. 1385 * 1386 * @param obj the object to compare 1387 * @return true if {@code obj} equals to this or the referent of this 1388 * @see MethodType#equals(Object) 1389 * @see Object#equals(Object) 1390 */ 1391 @Override 1392 public boolean equals(Object obj) { 1393 Object mine = get(); 1394 if (obj instanceof WeakEntry) { 1395 Object that = ((WeakEntry) obj).get(); 1396 return (that == null || mine == null) ? (this == obj) : mine.equals(that); 1397 } 1398 return (mine == null) ? (obj == null) : mine.equals(obj); 1399 } 1400 1401 @Override 1402 public int hashCode() { 1403 return hashcode; 1404 } 1405 1406 } 1407 } 1408 1409 }