1 /* 2 * Copyright (c) 2008, 2018, 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 50 import static java.lang.invoke.MethodHandleStatics.UNSAFE; 51 import static java.lang.invoke.MethodHandleStatics.newIllegalArgumentException; 52 53 /** 54 * A method type represents the arguments and return type accepted and 55 * returned by a method handle, or the arguments and return type passed 56 * and expected by a method handle caller. Method types must be properly 57 * matched between a method handle and all its callers, 58 * and the JVM's operations enforce this matching at, specifically 59 * during calls to {@link MethodHandle#invokeExact MethodHandle.invokeExact} 60 * and {@link MethodHandle#invoke MethodHandle.invoke}, and during execution 61 * of {@code invokedynamic} instructions. 62 * <p> 63 * The structure is a return type accompanied by any number of parameter types. 64 * The types (primitive, {@code void}, and reference) are represented by {@link Class} objects. 65 * (For ease of exposition, we treat {@code void} as if it were a type. 66 * In fact, it denotes the absence of a return type.) 67 * <p> 68 * All instances of {@code MethodType} are immutable. 69 * Two instances are completely interchangeable if they compare equal. 70 * Equality depends on pairwise correspondence of the return and parameter types and on nothing else. 71 * <p> 72 * This type can be created only by factory methods. 73 * All factory methods may cache values, though caching is not guaranteed. 74 * Some factory methods are static, while others are virtual methods which 75 * modify precursor method types, e.g., by changing a selected parameter. 76 * <p> 77 * Factory methods which operate on groups of parameter types 78 * are systematically presented in two versions, so that both Java arrays and 79 * Java lists can be used to work with groups of parameter types. 80 * The query methods {@code parameterArray} and {@code parameterList} 81 * also provide a choice between arrays and lists. 82 * <p> 83 * {@code MethodType} objects are sometimes derived from bytecode instructions 84 * such as {@code invokedynamic}, specifically from the type descriptor strings associated 85 * with the instructions in a class file's constant pool. 86 * <p> 87 * Like classes and strings, method types can also be represented directly 88 * in a class file's constant pool as constants. 89 * A method type may be loaded by an {@code ldc} instruction which refers 90 * to a suitable {@code CONSTANT_MethodType} constant pool entry. 91 * The entry refers to a {@code CONSTANT_Utf8} spelling for the descriptor string. 92 * (For full details on method type constants, 93 * see sections 4.4.8 and 5.4.3.5 of the Java Virtual Machine Specification.) 94 * <p> 95 * When the JVM materializes a {@code MethodType} from a descriptor string, 96 * all classes named in the descriptor must be accessible, and will be loaded. 97 * (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.) 98 * This loading may occur at any time before the {@code MethodType} object is first derived. 99 * @author John Rose, JSR 292 EG 100 * @since 1.7 101 */ 102 public final 103 class MethodType 104 implements Constable, 105 TypeDescriptor.OfMethod<Class<?>, MethodType>, 106 java.io.Serializable { 107 private static final long serialVersionUID = 292L; // {rtype, {ptype...}} 108 109 // The rtype and ptypes fields define the structural identity of the method type: 110 private final @Stable Class<?> rtype; 111 private final @Stable Class<?>[] ptypes; 112 113 // The remaining fields are caches of various sorts: 114 private @Stable MethodTypeForm form; // erased form, plus cached data about primitives 115 private @Stable MethodType wrapAlt; // alternative wrapped/unwrapped version 116 private @Stable Invokers invokers; // cache of handy higher-order adapters 117 private @Stable String methodDescriptor; // cache for toMethodDescriptorString 118 119 /** 120 * Constructor that performs no copying or validation. 121 * Should only be called from the factory method makeImpl 122 */ MethodType(Class<?> rtype, Class<?>[] ptypes)123 private MethodType(Class<?> rtype, Class<?>[] ptypes) { 124 this.rtype = rtype; 125 this.ptypes = ptypes; 126 } 127 form()128 /*trusted*/ MethodTypeForm form() { return form; } rtype()129 /*trusted*/ Class<?> rtype() { return rtype; } ptypes()130 /*trusted*/ Class<?>[] ptypes() { return ptypes; } 131 setForm(MethodTypeForm f)132 void setForm(MethodTypeForm f) { form = f; } 133 134 /** This number, mandated by the JVM spec as 255, 135 * is the maximum number of <em>slots</em> 136 * that any Java method can receive in its argument list. 137 * It limits both JVM signatures and method type objects. 138 * The longest possible invocation will look like 139 * {@code staticMethod(arg1, arg2, ..., arg255)} or 140 * {@code x.virtualMethod(arg1, arg2, ..., arg254)}. 141 */ 142 /*non-public*/ static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec. 143 144 /** This number is the maximum arity of a method handle, 254. 145 * It is derived from the absolute JVM-imposed arity by subtracting one, 146 * which is the slot occupied by the method handle itself at the 147 * beginning of the argument list used to invoke the method handle. 148 * The longest possible invocation will look like 149 * {@code mh.invoke(arg1, arg2, ..., arg254)}. 150 */ 151 // Issue: Should we allow MH.invokeWithArguments to go to the full 255? 152 /*non-public*/ static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver 153 154 /** This number is the maximum arity of a method handle invoker, 253. 155 * It is derived from the absolute JVM-imposed arity by subtracting two, 156 * which are the slots occupied by invoke method handle, and the 157 * target method handle, which are both at the beginning of the argument 158 * list used to invoke the target method handle. 159 * The longest possible invocation will look like 160 * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}. 161 */ 162 /*non-public*/ static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker 163 checkRtype(Class<?> rtype)164 private static void checkRtype(Class<?> rtype) { 165 Objects.requireNonNull(rtype); 166 } checkPtype(Class<?> ptype)167 private static void checkPtype(Class<?> ptype) { 168 Objects.requireNonNull(ptype); 169 if (ptype == void.class) 170 throw newIllegalArgumentException("parameter type cannot be void"); 171 } 172 /** Return number of extra slots (count of long/double args). */ checkPtypes(Class<?>[] ptypes)173 private static int checkPtypes(Class<?>[] ptypes) { 174 int slots = 0; 175 for (Class<?> ptype : ptypes) { 176 checkPtype(ptype); 177 if (ptype == double.class || ptype == long.class) { 178 slots++; 179 } 180 } 181 checkSlotCount(ptypes.length + slots); 182 return slots; 183 } 184 185 static { 186 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work: assert(MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0187 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0); 188 } checkSlotCount(int count)189 static void checkSlotCount(int count) { 190 if ((count & MAX_JVM_ARITY) != count) 191 throw newIllegalArgumentException("bad parameter count "+count); 192 } newIndexOutOfBoundsException(Object num)193 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) { 194 if (num instanceof Integer) num = "bad index: "+num; 195 return new IndexOutOfBoundsException(num.toString()); 196 } 197 198 static final ConcurrentWeakInternSet<MethodType> internTable = new ConcurrentWeakInternSet<>(); 199 200 static final Class<?>[] NO_PTYPES = {}; 201 202 /** 203 * Finds or creates an instance of the given method type. 204 * @param rtype the return type 205 * @param ptypes the parameter types 206 * @return a method type with the given components 207 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null 208 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class} 209 */ 210 public static methodType(Class<?> rtype, Class<?>[] ptypes)211 MethodType methodType(Class<?> rtype, Class<?>[] ptypes) { 212 return makeImpl(rtype, ptypes, false); 213 } 214 215 /** 216 * Finds or creates a method type with the given components. 217 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 218 * @param rtype the return type 219 * @param ptypes the parameter types 220 * @return a method type with the given components 221 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null 222 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class} 223 */ 224 public static methodType(Class<?> rtype, List<Class<?>> ptypes)225 MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) { 226 boolean notrust = false; // random List impl. could return evil ptypes array 227 return makeImpl(rtype, listToArray(ptypes), notrust); 228 } 229 listToArray(List<Class<?>> ptypes)230 private static Class<?>[] listToArray(List<Class<?>> ptypes) { 231 // sanity check the size before the toArray call, since size might be huge 232 checkSlotCount(ptypes.size()); 233 return ptypes.toArray(NO_PTYPES); 234 } 235 236 /** 237 * Finds or creates a method type with the given components. 238 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 239 * The leading parameter type is prepended to the remaining array. 240 * @param rtype the return type 241 * @param ptype0 the first parameter type 242 * @param ptypes the remaining parameter types 243 * @return a method type with the given components 244 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null 245 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class} 246 */ 247 public static methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes)248 MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) { 249 Class<?>[] ptypes1 = new Class<?>[1+ptypes.length]; 250 ptypes1[0] = ptype0; 251 System.arraycopy(ptypes, 0, ptypes1, 1, ptypes.length); 252 return makeImpl(rtype, ptypes1, true); 253 } 254 255 /** 256 * Finds or creates a method type with the given components. 257 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 258 * The resulting method has no parameter types. 259 * @param rtype the return type 260 * @return a method type with the given return value 261 * @throws NullPointerException if {@code rtype} is null 262 */ 263 public static methodType(Class<?> rtype)264 MethodType methodType(Class<?> rtype) { 265 return makeImpl(rtype, NO_PTYPES, true); 266 } 267 268 /** 269 * Finds or creates a method type with the given components. 270 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 271 * The resulting method has the single given parameter type. 272 * @param rtype the return type 273 * @param ptype0 the parameter type 274 * @return a method type with the given return value and parameter type 275 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null 276 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class} 277 */ 278 public static methodType(Class<?> rtype, Class<?> ptype0)279 MethodType methodType(Class<?> rtype, Class<?> ptype0) { 280 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true); 281 } 282 283 /** 284 * Finds or creates a method type with the given components. 285 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 286 * The resulting method has the same parameter types as {@code ptypes}, 287 * and the specified return type. 288 * @param rtype the return type 289 * @param ptypes the method type which supplies the parameter types 290 * @return a method type with the given components 291 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null 292 */ 293 public static methodType(Class<?> rtype, MethodType ptypes)294 MethodType methodType(Class<?> rtype, MethodType ptypes) { 295 return makeImpl(rtype, ptypes.ptypes, true); 296 } 297 298 /** 299 * Sole factory method to find or create an interned method type. 300 * @param rtype desired return type 301 * @param ptypes desired parameter types 302 * @param trusted whether the ptypes can be used without cloning 303 * @return the unique method type of the desired structure 304 */ 305 /*trusted*/ static makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted)306 MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) { 307 if (ptypes.length == 0) { 308 ptypes = NO_PTYPES; trusted = true; 309 } 310 MethodType primordialMT = new MethodType(rtype, ptypes); 311 MethodType mt = internTable.get(primordialMT); 312 if (mt != null) 313 return mt; 314 315 // promote the object to the Real Thing, and reprobe 316 MethodType.checkRtype(rtype); 317 if (trusted) { 318 MethodType.checkPtypes(ptypes); 319 mt = primordialMT; 320 } else { 321 // Make defensive copy then validate 322 ptypes = Arrays.copyOf(ptypes, ptypes.length); 323 MethodType.checkPtypes(ptypes); 324 mt = new MethodType(rtype, ptypes); 325 } 326 mt.form = MethodTypeForm.findForm(mt); 327 return internTable.add(mt); 328 } 329 private static final @Stable MethodType[] objectOnlyTypes = new MethodType[20]; 330 331 /** 332 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array. 333 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 334 * All parameters and the return type will be {@code Object}, 335 * except the final array parameter if any, which will be {@code Object[]}. 336 * @param objectArgCount number of parameters (excluding the final array parameter if any) 337 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]} 338 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments 339 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true) 340 * @see #genericMethodType(int) 341 */ 342 public static genericMethodType(int objectArgCount, boolean finalArray)343 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 genericMethodType(int objectArgCount)372 MethodType genericMethodType(int objectArgCount) { 373 return genericMethodType(objectArgCount, false); 374 } 375 376 /** 377 * Finds or creates a method type with a single different parameter type. 378 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 379 * @param num the index (zero-based) of the parameter type to change 380 * @param nptype a new parameter type to replace the old one with 381 * @return the same type, except with the selected parameter changed 382 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()} 383 * @throws IllegalArgumentException if {@code nptype} is {@code void.class} 384 * @throws NullPointerException if {@code nptype} is null 385 */ changeParameterType(int num, Class<?> nptype)386 public MethodType changeParameterType(int num, Class<?> nptype) { 387 if (parameterType(num) == nptype) return this; 388 checkPtype(nptype); 389 Class<?>[] nptypes = ptypes.clone(); 390 nptypes[num] = nptype; 391 return makeImpl(rtype, nptypes, true); 392 } 393 394 /** 395 * Finds or creates a method type with additional parameter types. 396 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 397 * @param num the position (zero-based) of the inserted parameter type(s) 398 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 399 * @return the same type, except with the selected parameter(s) inserted 400 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()} 401 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 402 * or if the resulting method type would have more than 255 parameter slots 403 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 404 */ insertParameterTypes(int num, Class<?>... ptypesToInsert)405 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) { 406 int len = ptypes.length; 407 if (num < 0 || num > len) 408 throw newIndexOutOfBoundsException(num); 409 int ins = checkPtypes(ptypesToInsert); 410 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins); 411 int ilen = ptypesToInsert.length; 412 if (ilen == 0) return this; 413 Class<?>[] nptypes = new Class<?>[len + ilen]; 414 if (num > 0) { 415 System.arraycopy(ptypes, 0, nptypes, 0, num); 416 } 417 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen); 418 if (num < len) { 419 System.arraycopy(ptypes, num, nptypes, num+ilen, len-num); 420 } 421 return makeImpl(rtype, nptypes, true); 422 } 423 424 /** 425 * Finds or creates a method type with additional parameter types. 426 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 427 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list 428 * @return the same type, except with the selected parameter(s) appended 429 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 430 * or if the resulting method type would have more than 255 parameter slots 431 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 432 */ appendParameterTypes(Class<?>.... ptypesToInsert)433 public MethodType appendParameterTypes(Class<?>... ptypesToInsert) { 434 return insertParameterTypes(parameterCount(), ptypesToInsert); 435 } 436 437 /** 438 * Finds or creates a method type with additional parameter types. 439 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 440 * @param num the position (zero-based) of the inserted parameter type(s) 441 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 442 * @return the same type, except with the selected parameter(s) inserted 443 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()} 444 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 445 * or if the resulting method type would have more than 255 parameter slots 446 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 447 */ insertParameterTypes(int num, List<Class<?>> ptypesToInsert)448 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) { 449 return insertParameterTypes(num, listToArray(ptypesToInsert)); 450 } 451 452 /** 453 * Finds or creates a method type with additional parameter types. 454 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 455 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list 456 * @return the same type, except with the selected parameter(s) appended 457 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 458 * or if the resulting method type would have more than 255 parameter slots 459 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 460 */ appendParameterTypes(List<Class<?>> ptypesToInsert)461 public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) { 462 return insertParameterTypes(parameterCount(), ptypesToInsert); 463 } 464 465 /** 466 * Finds or creates a method type with modified parameter types. 467 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 468 * @param start the position (zero-based) of the first replaced parameter type(s) 469 * @param end the position (zero-based) after the last replaced parameter type(s) 470 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 471 * @return the same type, except with the selected parameter(s) replaced 472 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()} 473 * or if {@code end} is negative or greater than {@code parameterCount()} 474 * or if {@code start} is greater than {@code end} 475 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 476 * or if the resulting method type would have more than 255 parameter slots 477 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 478 */ replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert)479 /*non-public*/ 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 */ asSpreaderType(Class<?> arrayType, int pos, int arrayLength)497 /*non-public*/ MethodType asSpreaderType(Class<?> arrayType, int pos, int arrayLength) { 498 assert(parameterCount() >= arrayLength); 499 int spreadPos = pos; 500 if (arrayLength == 0) return this; // nothing to change 501 if (arrayType == Object[].class) { 502 if (isGeneric()) return this; // nothing to change 503 if (spreadPos == 0) { 504 // no leading arguments to preserve; go generic 505 MethodType res = genericMethodType(arrayLength); 506 if (rtype != Object.class) { 507 res = res.changeReturnType(rtype); 508 } 509 return res; 510 } 511 } 512 Class<?> elemType = arrayType.getComponentType(); 513 assert(elemType != null); 514 for (int i = spreadPos; i < spreadPos + arrayLength; i++) { 515 if (ptypes[i] != elemType) { 516 Class<?>[] fixedPtypes = ptypes.clone(); 517 Arrays.fill(fixedPtypes, i, spreadPos + arrayLength, elemType); 518 return methodType(rtype, fixedPtypes); 519 } 520 } 521 return this; // arguments check out; no change 522 } 523 524 /** Return the leading parameter type, which must exist and be a reference. 525 * @return the leading parameter type, after error checks 526 */ leadingReferenceParameter()527 /*non-public*/ Class<?> leadingReferenceParameter() { 528 Class<?> ptype; 529 if (ptypes.length == 0 || 530 (ptype = ptypes[0]).isPrimitive()) 531 throw newIllegalArgumentException("no leading reference parameter"); 532 return ptype; 533 } 534 535 /** Delete the last parameter type and replace it with arrayLength copies of the component type of arrayType. 536 * @param arrayType any array type 537 * @param pos position at which to insert parameters 538 * @param arrayLength the number of parameter types to insert 539 * @return the resulting type 540 */ asCollectorType(Class<?> arrayType, int pos, int arrayLength)541 /*non-public*/ MethodType asCollectorType(Class<?> arrayType, int pos, int arrayLength) { 542 assert(parameterCount() >= 1); 543 assert(pos < ptypes.length); 544 assert(ptypes[pos].isAssignableFrom(arrayType)); 545 MethodType res; 546 if (arrayType == Object[].class) { 547 res = genericMethodType(arrayLength); 548 if (rtype != Object.class) { 549 res = res.changeReturnType(rtype); 550 } 551 } else { 552 Class<?> elemType = arrayType.getComponentType(); 553 assert(elemType != null); 554 res = methodType(rtype, Collections.nCopies(arrayLength, elemType)); 555 } 556 if (ptypes.length == 1) { 557 return res; 558 } else { 559 // insert after (if need be), then before 560 if (pos < ptypes.length - 1) { 561 res = res.insertParameterTypes(arrayLength, Arrays.copyOfRange(ptypes, pos + 1, ptypes.length)); 562 } 563 return res.insertParameterTypes(0, Arrays.copyOf(ptypes, pos)); 564 } 565 } 566 567 /** 568 * Finds or creates a method type with some parameter types omitted. 569 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 570 * @param start the index (zero-based) of the first parameter type to remove 571 * @param end the index (greater than {@code start}) of the first parameter type after not to remove 572 * @return the same type, except with the selected parameter(s) removed 573 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()} 574 * or if {@code end} is negative or greater than {@code parameterCount()} 575 * or if {@code start} is greater than {@code end} 576 */ 577 public MethodType dropParameterTypes(int start, int end) { 578 int len = ptypes.length; 579 if (!(0 <= start && start <= end && end <= len)) 580 throw newIndexOutOfBoundsException("start="+start+" end="+end); 581 if (start == end) return this; 582 Class<?>[] nptypes; 583 if (start == 0) { 584 if (end == len) { 585 // drop all parameters 586 nptypes = NO_PTYPES; 587 } else { 588 // drop initial parameter(s) 589 nptypes = Arrays.copyOfRange(ptypes, end, len); 590 } 591 } else { 592 if (end == len) { 593 // drop trailing parameter(s) 594 nptypes = Arrays.copyOfRange(ptypes, 0, start); 595 } else { 596 int tail = len - end; 597 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail); 598 System.arraycopy(ptypes, end, nptypes, start, tail); 599 } 600 } 601 return makeImpl(rtype, nptypes, true); 602 } 603 604 /** 605 * Finds or creates a method type with a different return type. 606 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 607 * @param nrtype a return parameter type to replace the old one with 608 * @return the same type, except with the return type change 609 * @throws NullPointerException if {@code nrtype} is null 610 */ 611 public MethodType changeReturnType(Class<?> nrtype) { 612 if (returnType() == nrtype) return this; 613 return makeImpl(nrtype, ptypes, true); 614 } 615 616 /** 617 * Reports if this type contains a primitive argument or return value. 618 * The return type {@code void} counts as a primitive. 619 * @return true if any of the types are primitives 620 */ 621 public boolean hasPrimitives() { 622 return form.hasPrimitives(); 623 } 624 625 /** 626 * Reports if this type contains a wrapper argument or return value. 627 * Wrappers are types which box primitive values, such as {@link Integer}. 628 * The reference type {@code java.lang.Void} counts as a wrapper, 629 * if it occurs as a return type. 630 * @return true if any of the types are wrappers 631 */ 632 public boolean hasWrappers() { 633 return unwrap() != this; 634 } 635 636 /** 637 * Erases all reference types to {@code Object}. 638 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 639 * All primitive types (including {@code void}) will remain unchanged. 640 * @return a version of the original type with all reference types replaced 641 */ 642 public MethodType erase() { 643 return form.erasedType(); 644 } 645 646 /** 647 * Erases all reference types to {@code Object}, and all subword types to {@code int}. 648 * This is the reduced type polymorphism used by private methods 649 * such as {@link MethodHandle#invokeBasic invokeBasic}. 650 * @return a version of the original type with all reference and subword types replaced 651 */ 652 /*non-public*/ MethodType basicType() { 653 return form.basicType(); 654 } 655 656 private static final @Stable Class<?>[] METHOD_HANDLE_ARRAY 657 = new Class<?>[] { MethodHandle.class }; 658 659 /** 660 * @return a version of the original type with MethodHandle prepended as the first argument 661 */ 662 /*non-public*/ MethodType invokerType() { 663 return insertParameterTypes(0, METHOD_HANDLE_ARRAY); 664 } 665 666 /** 667 * Converts all types, both reference and primitive, to {@code Object}. 668 * Convenience method for {@link #genericMethodType(int) genericMethodType}. 669 * The expression {@code type.wrap().erase()} produces the same value 670 * as {@code type.generic()}. 671 * @return a version of the original type with all types replaced 672 */ 673 public MethodType generic() { 674 return genericMethodType(parameterCount()); 675 } 676 677 /*non-public*/ boolean isGeneric() { 678 return this == erase() && !hasPrimitives(); 679 } 680 681 /** 682 * Converts all primitive types to their corresponding wrapper types. 683 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 684 * All reference types (including wrapper types) will remain unchanged. 685 * A {@code void} return type is changed to the type {@code java.lang.Void}. 686 * The expression {@code type.wrap().erase()} produces the same value 687 * as {@code type.generic()}. 688 * @return a version of the original type with all primitive types replaced 689 */ 690 public MethodType wrap() { 691 return hasPrimitives() ? wrapWithPrims(this) : this; 692 } 693 694 /** 695 * Converts all wrapper types to their corresponding primitive types. 696 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 697 * All primitive types (including {@code void}) will remain unchanged. 698 * A return type of {@code java.lang.Void} is changed to {@code void}. 699 * @return a version of the original type with all wrapper types replaced 700 */ 701 public MethodType unwrap() { 702 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this); 703 return unwrapWithNoPrims(noprims); 704 } 705 706 private static MethodType wrapWithPrims(MethodType pt) { 707 assert(pt.hasPrimitives()); 708 MethodType wt = pt.wrapAlt; 709 if (wt == null) { 710 // fill in lazily 711 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP, MethodTypeForm.WRAP); 712 assert(wt != null); 713 pt.wrapAlt = wt; 714 } 715 return wt; 716 } 717 718 private static MethodType unwrapWithNoPrims(MethodType wt) { 719 assert(!wt.hasPrimitives()); 720 MethodType uwt = wt.wrapAlt; 721 if (uwt == null) { 722 // fill in lazily 723 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP, MethodTypeForm.UNWRAP); 724 if (uwt == null) 725 uwt = wt; // type has no wrappers or prims at all 726 wt.wrapAlt = uwt; 727 } 728 return uwt; 729 } 730 731 /** 732 * Returns the parameter type at the specified index, within this method type. 733 * @param num the index (zero-based) of the desired parameter type 734 * @return the selected parameter type 735 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()} 736 */ 737 public Class<?> parameterType(int num) { 738 return ptypes[num]; 739 } 740 /** 741 * Returns the number of parameter types in this method type. 742 * @return the number of parameter types 743 */ 744 public int parameterCount() { 745 return ptypes.length; 746 } 747 /** 748 * Returns the return type of this method type. 749 * @return the return type 750 */ 751 public Class<?> returnType() { 752 return rtype; 753 } 754 755 /** 756 * Presents the parameter types as a list (a convenience method). 757 * The list will be immutable. 758 * @return the parameter types (as an immutable list) 759 */ 760 public List<Class<?>> parameterList() { 761 return Collections.unmodifiableList(Arrays.asList(ptypes.clone())); 762 } 763 764 /** 765 * Returns the last parameter type of this method type. 766 * If this type has no parameters, the sentinel value 767 * {@code void.class} is returned instead. 768 * @apiNote 769 * <p> 770 * The sentinel value is chosen so that reflective queries can be 771 * made directly against the result value. 772 * The sentinel value cannot be confused with a real parameter, 773 * since {@code void} is never acceptable as a parameter type. 774 * For variable arity invocation modes, the expression 775 * {@link Class#getComponentType lastParameterType().getComponentType()} 776 * is useful to query the type of the "varargs" parameter. 777 * @return the last parameter type if any, else {@code void.class} 778 * @since 10 779 */ 780 public Class<?> lastParameterType() { 781 int len = ptypes.length; 782 return len == 0 ? void.class : ptypes[len-1]; 783 } 784 785 /** 786 * Presents the parameter types as an array (a convenience method). 787 * Changes to the array will not result in changes to the type. 788 * @return the parameter types (as a fresh copy if necessary) 789 */ 790 public Class<?>[] parameterArray() { 791 return ptypes.clone(); 792 } 793 794 /** 795 * Compares the specified object with this type for equality. 796 * That is, it returns {@code true} if and only if the specified object 797 * is also a method type with exactly the same parameters and return type. 798 * @param x object to compare 799 * @see Object#equals(Object) 800 */ 801 // This implementation may also return true if x is a WeakEntry containing 802 // a method type that is equal to this. This is an internal implementation 803 // detail to allow for faster method type lookups. 804 // See ConcurrentWeakInternSet.WeakEntry#equals(Object) 805 @Override 806 public boolean equals(Object x) { 807 if (this == x) { 808 return true; 809 } 810 if (x instanceof MethodType) { 811 return equals((MethodType)x); 812 } 813 if (x instanceof ConcurrentWeakInternSet.WeakEntry) { 814 Object o = ((ConcurrentWeakInternSet.WeakEntry)x).get(); 815 if (o instanceof MethodType) { 816 return equals((MethodType)o); 817 } 818 } 819 return false; 820 } 821 822 private boolean equals(MethodType that) { 823 return this.rtype == that.rtype 824 && Arrays.equals(this.ptypes, that.ptypes); 825 } 826 827 /** 828 * Returns the hash code value for this method type. 829 * It is defined to be the same as the hashcode of a List 830 * whose elements are the return type followed by the 831 * parameter types. 832 * @return the hash code value for this method type 833 * @see Object#hashCode() 834 * @see #equals(Object) 835 * @see List#hashCode() 836 */ 837 @Override 838 public int hashCode() { 839 int hashCode = 31 + rtype.hashCode(); 840 for (Class<?> ptype : ptypes) 841 hashCode = 31 * hashCode + ptype.hashCode(); 842 return hashCode; 843 } 844 845 /** 846 * Returns a string representation of the method type, 847 * of the form {@code "(PT0,PT1...)RT"}. 848 * The string representation of a method type is a 849 * parenthesis enclosed, comma separated list of type names, 850 * followed immediately by the return type. 851 * <p> 852 * Each type is represented by its 853 * {@link java.lang.Class#getSimpleName simple name}. 854 */ 855 @Override 856 public String toString() { 857 StringJoiner sj = new StringJoiner(",", "(", 858 ")" + rtype.getSimpleName()); 859 for (int i = 0; i < ptypes.length; i++) { 860 sj.add(ptypes[i].getSimpleName()); 861 } 862 return sj.toString(); 863 } 864 865 /** True if my parameter list is effectively identical to the given full list, 866 * after skipping the given number of my own initial parameters. 867 * In other words, after disregarding {@code skipPos} parameters, 868 * my remaining parameter list is no longer than the {@code fullList}, and 869 * is equal to the same-length initial sublist of {@code fullList}. 870 */ 871 /*non-public*/ 872 boolean effectivelyIdenticalParameters(int skipPos, List<Class<?>> fullList) { 873 int myLen = ptypes.length, fullLen = fullList.size(); 874 if (skipPos > myLen || myLen - skipPos > fullLen) 875 return false; 876 List<Class<?>> myList = Arrays.asList(ptypes); 877 if (skipPos != 0) { 878 myList = myList.subList(skipPos, myLen); 879 myLen -= skipPos; 880 } 881 if (fullLen == myLen) 882 return myList.equals(fullList); 883 else 884 return myList.equals(fullList.subList(0, myLen)); 885 } 886 887 /** True if the old return type can always be viewed (w/o casting) under new return type, 888 * and the new parameters can be viewed (w/o casting) under the old parameter types. 889 */ 890 /*non-public*/ 891 boolean isViewableAs(MethodType newType, boolean keepInterfaces) { 892 if (!VerifyType.isNullConversion(returnType(), newType.returnType(), keepInterfaces)) 893 return false; 894 if (form == newType.form && form.erasedType == this) 895 return true; // my reference parameters are all Object 896 if (ptypes == newType.ptypes) 897 return true; 898 int argc = parameterCount(); 899 if (argc != newType.parameterCount()) 900 return false; 901 for (int i = 0; i < argc; i++) { 902 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i), keepInterfaces)) 903 return false; 904 } 905 return true; 906 } 907 /*non-public*/ 908 boolean isConvertibleTo(MethodType newType) { 909 MethodTypeForm oldForm = this.form(); 910 MethodTypeForm newForm = newType.form(); 911 if (oldForm == newForm) 912 // same parameter count, same primitive/object mix 913 return true; 914 if (!canConvert(returnType(), newType.returnType())) 915 return false; 916 Class<?>[] srcTypes = newType.ptypes; 917 Class<?>[] dstTypes = ptypes; 918 if (srcTypes == dstTypes) 919 return true; 920 int argc; 921 if ((argc = srcTypes.length) != dstTypes.length) 922 return false; 923 if (argc <= 1) { 924 if (argc == 1 && !canConvert(srcTypes[0], dstTypes[0])) 925 return false; 926 return true; 927 } 928 if ((oldForm.primitiveParameterCount() == 0 && oldForm.erasedType == this) || 929 (newForm.primitiveParameterCount() == 0 && newForm.erasedType == newType)) { 930 // Somewhat complicated test to avoid a loop of 2 or more trips. 931 // If either type has only Object parameters, we know we can convert. 932 assert(canConvertParameters(srcTypes, dstTypes)); 933 return true; 934 } 935 return canConvertParameters(srcTypes, dstTypes); 936 } 937 938 /** Returns true if MHs.explicitCastArguments produces the same result as MH.asType. 939 * If the type conversion is impossible for either, the result should be false. 940 */ 941 /*non-public*/ 942 boolean explicitCastEquivalentToAsType(MethodType newType) { 943 if (this == newType) return true; 944 if (!explicitCastEquivalentToAsType(rtype, newType.rtype)) { 945 return false; 946 } 947 Class<?>[] srcTypes = newType.ptypes; 948 Class<?>[] dstTypes = ptypes; 949 if (dstTypes == srcTypes) { 950 return true; 951 } 952 assert(dstTypes.length == srcTypes.length); 953 for (int i = 0; i < dstTypes.length; i++) { 954 if (!explicitCastEquivalentToAsType(srcTypes[i], dstTypes[i])) { 955 return false; 956 } 957 } 958 return true; 959 } 960 961 /** Reports true if the src can be converted to the dst, by both asType and MHs.eCE, 962 * and with the same effect. 963 * MHs.eCA has the following "upgrades" to MH.asType: 964 * 1. interfaces are unchecked (that is, treated as if aliased to Object) 965 * Therefore, {@code Object->CharSequence} is possible in both cases but has different semantics 966 * 2. the full matrix of primitive-to-primitive conversions is supported 967 * Narrowing like {@code long->byte} and basic-typing like {@code boolean->int} 968 * are not supported by asType, but anything supported by asType is equivalent 969 * with MHs.eCE. 970 * 3a. unboxing conversions can be followed by the full matrix of primitive conversions 971 * 3b. unboxing of null is permitted (creates a zero primitive value) 972 * Other than interfaces, reference-to-reference conversions are the same. 973 * Boxing primitives to references is the same for both operators. 974 */ 975 private static boolean explicitCastEquivalentToAsType(Class<?> src, Class<?> dst) { 976 if (src == dst || dst == Object.class || dst == void.class) return true; 977 if (src.isPrimitive()) { 978 // Could be a prim/prim conversion, where casting is a strict superset. 979 // Or a boxing conversion, which is always to an exact wrapper class. 980 return canConvert(src, dst); 981 } else if (dst.isPrimitive()) { 982 // Unboxing behavior is different between MHs.eCA & MH.asType (see 3b). 983 return false; 984 } else { 985 // R->R always works, but we have to avoid a check-cast to an interface. 986 return !dst.isInterface() || dst.isAssignableFrom(src); 987 } 988 } 989 990 private boolean canConvertParameters(Class<?>[] srcTypes, Class<?>[] dstTypes) { 991 for (int i = 0; i < srcTypes.length; i++) { 992 if (!canConvert(srcTypes[i], dstTypes[i])) { 993 return false; 994 } 995 } 996 return true; 997 } 998 999 /*non-public*/ 1000 static boolean canConvert(Class<?> src, Class<?> dst) { 1001 // short-circuit a few cases: 1002 if (src == dst || src == Object.class || dst == Object.class) return true; 1003 // the remainder of this logic is documented in MethodHandle.asType 1004 if (src.isPrimitive()) { 1005 // can force void to an explicit null, a la reflect.Method.invoke 1006 // can also force void to a primitive zero, by analogy 1007 if (src == void.class) return true; //or !dst.isPrimitive()? 1008 Wrapper sw = Wrapper.forPrimitiveType(src); 1009 if (dst.isPrimitive()) { 1010 // P->P must widen 1011 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw); 1012 } else { 1013 // P->R must box and widen 1014 return dst.isAssignableFrom(sw.wrapperType()); 1015 } 1016 } else if (dst.isPrimitive()) { 1017 // any value can be dropped 1018 if (dst == void.class) return true; 1019 Wrapper dw = Wrapper.forPrimitiveType(dst); 1020 // R->P must be able to unbox (from a dynamically chosen type) and widen 1021 // For example: 1022 // Byte/Number/Comparable/Object -> dw:Byte -> byte. 1023 // Character/Comparable/Object -> dw:Character -> char 1024 // Boolean/Comparable/Object -> dw:Boolean -> boolean 1025 // This means that dw must be cast-compatible with src. 1026 if (src.isAssignableFrom(dw.wrapperType())) { 1027 return true; 1028 } 1029 // The above does not work if the source reference is strongly typed 1030 // to a wrapper whose primitive must be widened. For example: 1031 // Byte -> unbox:byte -> short/int/long/float/double 1032 // Character -> unbox:char -> int/long/float/double 1033 if (Wrapper.isWrapperType(src) && 1034 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) { 1035 // can unbox from src and then widen to dst 1036 return true; 1037 } 1038 // We have already covered cases which arise due to runtime unboxing 1039 // of a reference type which covers several wrapper types: 1040 // Object -> cast:Integer -> unbox:int -> long/float/double 1041 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double 1042 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a 1043 // subclass of Number which wraps a value that can convert to char. 1044 // Since there is none, we don't need an extra check here to cover char or boolean. 1045 return false; 1046 } else { 1047 // R->R always works, since null is always valid dynamically 1048 return true; 1049 } 1050 } 1051 1052 /// Queries which have to do with the bytecode architecture 1053 1054 /** Reports the number of JVM stack slots required to invoke a method 1055 * of this type. Note that (for historical reasons) the JVM requires 1056 * a second stack slot to pass long and double arguments. 1057 * So this method returns {@link #parameterCount() parameterCount} plus the 1058 * number of long and double parameters (if any). 1059 * <p> 1060 * This method is included for the benefit of applications that must 1061 * generate bytecodes that process method handles and invokedynamic. 1062 * @return the number of JVM stack slots for this type's parameters 1063 */ 1064 /*non-public*/ int parameterSlotCount() { 1065 return form.parameterSlotCount(); 1066 } 1067 1068 /*non-public*/ Invokers invokers() { 1069 Invokers inv = invokers; 1070 if (inv != null) return inv; 1071 invokers = inv = new Invokers(this); 1072 return inv; 1073 } 1074 1075 /** Reports the number of JVM stack slots which carry all parameters including and after 1076 * the given position, which must be in the range of 0 to 1077 * {@code parameterCount} inclusive. Successive parameters are 1078 * more shallowly stacked, and parameters are indexed in the bytecodes 1079 * according to their trailing edge. Thus, to obtain the depth 1080 * in the outgoing call stack of parameter {@code N}, obtain 1081 * the {@code parameterSlotDepth} of its trailing edge 1082 * at position {@code N+1}. 1083 * <p> 1084 * Parameters of type {@code long} and {@code double} occupy 1085 * two stack slots (for historical reasons) and all others occupy one. 1086 * Therefore, the number returned is the number of arguments 1087 * <em>including</em> and <em>after</em> the given parameter, 1088 * <em>plus</em> the number of long or double arguments 1089 * at or after the argument for the given parameter. 1090 * <p> 1091 * This method is included for the benefit of applications that must 1092 * generate bytecodes that process method handles and invokedynamic. 1093 * @param num an index (zero-based, inclusive) within the parameter types 1094 * @return the index of the (shallowest) JVM stack slot transmitting the 1095 * given parameter 1096 * @throws IllegalArgumentException if {@code num} is negative or greater than {@code parameterCount()} 1097 */ 1098 /*non-public*/ int parameterSlotDepth(int num) { 1099 if (num < 0 || num > ptypes.length) 1100 parameterType(num); // force a range check 1101 return form.parameterToArgSlot(num-1); 1102 } 1103 1104 /** Reports the number of JVM stack slots required to receive a return value 1105 * from a method of this type. 1106 * If the {@link #returnType() return type} is void, it will be zero, 1107 * else if the return type is long or double, it will be two, else one. 1108 * <p> 1109 * This method is included for the benefit of applications that must 1110 * generate bytecodes that process method handles and invokedynamic. 1111 * @return the number of JVM stack slots (0, 1, or 2) for this type's return value 1112 * Will be removed for PFD. 1113 */ 1114 /*non-public*/ int returnSlotCount() { 1115 return form.returnSlotCount(); 1116 } 1117 1118 /** 1119 * Finds or creates an instance of a method type, given the spelling of its bytecode descriptor. 1120 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 1121 * Any class or interface name embedded in the descriptor string 1122 * will be resolved by calling {@link ClassLoader#loadClass(java.lang.String)} 1123 * on the given loader (or if it is null, on the system class loader). 1124 * <p> 1125 * Note that it is possible to encounter method types which cannot be 1126 * constructed by this method, because their component types are 1127 * not all reachable from a common class loader. 1128 * <p> 1129 * This method is included for the benefit of applications that must 1130 * generate bytecodes that process method handles and {@code invokedynamic}. 1131 * @param descriptor a bytecode-level type descriptor string "(T...)T" 1132 * @param loader the class loader in which to look up the types 1133 * @return a method type matching the bytecode-level type descriptor 1134 * @throws NullPointerException if the string is null 1135 * @throws IllegalArgumentException if the string is not well-formed 1136 * @throws TypeNotPresentException if a named type cannot be found 1137 */ 1138 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader) 1139 throws IllegalArgumentException, TypeNotPresentException 1140 { 1141 return fromDescriptor(descriptor, 1142 (loader == null) ? ClassLoader.getSystemClassLoader() : loader); 1143 } 1144 1145 /** 1146 * Same as {@link #fromMethodDescriptorString(String, ClassLoader)}, but 1147 * {@code null} ClassLoader means the bootstrap loader is used here. 1148 * <p> 1149 * IMPORTANT: This method is preferable for JDK internal use as it more 1150 * correctly interprets {@code null} ClassLoader than 1151 * {@link #fromMethodDescriptorString(String, ClassLoader)}. 1152 * Use of this method also avoids early initialization issues when system 1153 * ClassLoader is not initialized yet. 1154 */ 1155 static MethodType fromDescriptor(String descriptor, ClassLoader loader) 1156 throws IllegalArgumentException, TypeNotPresentException 1157 { 1158 if (!descriptor.startsWith("(") || // also generates NPE if needed 1159 descriptor.indexOf(')') < 0 || 1160 descriptor.indexOf('.') >= 0) 1161 throw newIllegalArgumentException("not a method descriptor: "+descriptor); 1162 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader); 1163 Class<?> rtype = types.remove(types.size() - 1); 1164 Class<?>[] ptypes = listToArray(types); 1165 return makeImpl(rtype, ptypes, true); 1166 } 1167 1168 /** 1169 * Produces a bytecode descriptor representation of the method type. 1170 * <p> 1171 * Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}. 1172 * Two distinct classes which share a common name but have different class loaders 1173 * will appear identical when viewed within descriptor strings. 1174 * <p> 1175 * This method is included for the benefit of applications that must 1176 * generate bytecodes that process method handles and {@code invokedynamic}. 1177 * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString}, 1178 * because the latter requires a suitable class loader argument. 1179 * @return the bytecode type descriptor representation 1180 */ 1181 public String toMethodDescriptorString() { 1182 String desc = methodDescriptor; 1183 if (desc == null) { 1184 desc = BytecodeDescriptor.unparseMethod(this.rtype, this.ptypes); 1185 methodDescriptor = desc; 1186 } 1187 return desc; 1188 } 1189 1190 /** 1191 * Return a field type descriptor string for this type 1192 * 1193 * @return the descriptor string 1194 * @jvms 4.3.2 Field Descriptors 1195 * @since 12 1196 */ 1197 @Override 1198 public String descriptorString() { 1199 return toMethodDescriptorString(); 1200 } 1201 1202 /*non-public*/ static String toFieldDescriptorString(Class<?> cls) { 1203 return BytecodeDescriptor.unparse(cls); 1204 } 1205 1206 /** 1207 * Return a nominal descriptor for this instance, if one can be 1208 * constructed, or an empty {@link Optional} if one cannot be. 1209 * 1210 * @return An {@link Optional} containing the resulting nominal descriptor, 1211 * or an empty {@link Optional} if one cannot be constructed. 1212 * @since 12 1213 */ 1214 @Override 1215 public Optional<MethodTypeDesc> describeConstable() { 1216 try { 1217 return Optional.of(MethodTypeDesc.of(returnType().describeConstable().orElseThrow(), 1218 Stream.of(parameterArray()) 1219 .map(p -> p.describeConstable().orElseThrow()) 1220 .toArray(ClassDesc[]::new))); 1221 } 1222 catch (NoSuchElementException e) { 1223 return Optional.empty(); 1224 } 1225 } 1226 1227 /// Serialization. 1228 1229 /** 1230 * There are no serializable fields for {@code MethodType}. 1231 */ 1232 private static final java.io.ObjectStreamField[] serialPersistentFields = { }; 1233 1234 /** 1235 * Save the {@code MethodType} instance to a stream. 1236 * 1237 * @serialData 1238 * For portability, the serialized format does not refer to named fields. 1239 * Instead, the return type and parameter type arrays are written directly 1240 * from the {@code writeObject} method, using two calls to {@code s.writeObject} 1241 * as follows: 1242 * <blockquote><pre>{@code 1243 s.writeObject(this.returnType()); 1244 s.writeObject(this.parameterArray()); 1245 * }</pre></blockquote> 1246 * <p> 1247 * The deserialized field values are checked as if they were 1248 * provided to the factory method {@link #methodType(Class,Class[]) methodType}. 1249 * For example, null values, or {@code void} parameter types, 1250 * will lead to exceptions during deserialization. 1251 * @param s the stream to write the object to 1252 * @throws java.io.IOException if there is a problem writing the object 1253 */ 1254 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException { 1255 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array 1256 s.writeObject(returnType()); 1257 s.writeObject(parameterArray()); 1258 } 1259 1260 /** 1261 * Reconstitute the {@code MethodType} instance from a stream (that is, 1262 * deserialize it). 1263 * This instance is a scratch object with bogus final fields. 1264 * It provides the parameters to the factory method called by 1265 * {@link #readResolve readResolve}. 1266 * After that call it is discarded. 1267 * @param s the stream to read the object from 1268 * @throws java.io.IOException if there is a problem reading the object 1269 * @throws ClassNotFoundException if one of the component classes cannot be resolved 1270 * @see #readResolve 1271 * @see #writeObject 1272 */ 1273 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException { 1274 // Assign temporary defaults in case this object escapes 1275 MethodType_init(void.class, NO_PTYPES); 1276 1277 s.defaultReadObject(); // requires serialPersistentFields to be an empty array 1278 1279 Class<?> returnType = (Class<?>) s.readObject(); 1280 Class<?>[] parameterArray = (Class<?>[]) s.readObject(); 1281 parameterArray = parameterArray.clone(); // make sure it is unshared 1282 1283 // Assign deserialized values 1284 MethodType_init(returnType, parameterArray); 1285 } 1286 1287 // Initialization of state for deserialization only 1288 private void MethodType_init(Class<?> rtype, Class<?>[] ptypes) { 1289 // In order to communicate these values to readResolve, we must 1290 // store them into the implementation-specific final fields. 1291 checkRtype(rtype); 1292 checkPtypes(ptypes); 1293 UNSAFE.putReference(this, OffsetHolder.rtypeOffset, rtype); 1294 UNSAFE.putReference(this, OffsetHolder.ptypesOffset, ptypes); 1295 } 1296 1297 // Support for resetting final fields while deserializing. Implement Holder 1298 // pattern to make the rarely needed offset calculation lazy. 1299 private static class OffsetHolder { 1300 static final long rtypeOffset 1301 = UNSAFE.objectFieldOffset(MethodType.class, "rtype"); 1302 1303 static final long ptypesOffset 1304 = UNSAFE.objectFieldOffset(MethodType.class, "ptypes"); 1305 } 1306 1307 /** 1308 * Resolves and initializes a {@code MethodType} object 1309 * after serialization. 1310 * @return the fully initialized {@code MethodType} object 1311 */ 1312 private Object readResolve() { 1313 // Do not use a trusted path for deserialization: 1314 // return makeImpl(rtype, ptypes, true); 1315 // Verify all operands, and make sure ptypes is unshared: 1316 try { 1317 return methodType(rtype, ptypes); 1318 } finally { 1319 // Re-assign defaults in case this object escapes 1320 MethodType_init(void.class, NO_PTYPES); 1321 } 1322 } 1323 1324 /** 1325 * Simple implementation of weak concurrent intern set. 1326 * 1327 * @param <T> interned type 1328 */ 1329 private static class ConcurrentWeakInternSet<T> { 1330 1331 private final ConcurrentMap<WeakEntry<T>, WeakEntry<T>> map; 1332 private final ReferenceQueue<T> stale; 1333 1334 public ConcurrentWeakInternSet() { 1335 this.map = new ConcurrentHashMap<>(512); 1336 this.stale = new ReferenceQueue<>(); 1337 } 1338 1339 /** 1340 * Get the existing interned element. 1341 * This method returns null if no element is interned. 1342 * 1343 * @param elem element to look up 1344 * @return the interned element 1345 */ 1346 public T get(T elem) { 1347 if (elem == null) throw new NullPointerException(); 1348 expungeStaleElements(); 1349 1350 WeakEntry<T> value = map.get(elem); 1351 if (value != null) { 1352 T res = value.get(); 1353 if (res != null) { 1354 return res; 1355 } 1356 } 1357 return null; 1358 } 1359 1360 /** 1361 * Interns the element. 1362 * Always returns non-null element, matching the one in the intern set. 1363 * Under the race against another add(), it can return <i>different</i> 1364 * element, if another thread beats us to interning it. 1365 * 1366 * @param elem element to add 1367 * @return element that was actually added 1368 */ 1369 public T add(T elem) { 1370 if (elem == null) throw new NullPointerException(); 1371 1372 // Playing double race here, and so spinloop is required. 1373 // First race is with two concurrent updaters. 1374 // Second race is with GC purging weak ref under our feet. 1375 // Hopefully, we almost always end up with a single pass. 1376 T interned; 1377 WeakEntry<T> e = new WeakEntry<>(elem, stale); 1378 do { 1379 expungeStaleElements(); 1380 WeakEntry<T> exist = map.putIfAbsent(e, e); 1381 interned = (exist == null) ? elem : exist.get(); 1382 } while (interned == null); 1383 return interned; 1384 } 1385 1386 private void expungeStaleElements() { 1387 Reference<? extends T> reference; 1388 while ((reference = stale.poll()) != null) { 1389 map.remove(reference); 1390 } 1391 } 1392 1393 private static class WeakEntry<T> extends WeakReference<T> { 1394 1395 public final int hashcode; 1396 1397 public WeakEntry(T key, ReferenceQueue<T> queue) { 1398 super(key, queue); 1399 hashcode = key.hashCode(); 1400 } 1401 1402 /** 1403 * This implementation returns {@code true} if {@code obj} is another 1404 * {@code WeakEntry} whose referent is equals to this referent, or 1405 * if {@code obj} is equals to the referent of this. This allows 1406 * lookups to be made without wrapping in a {@code WeakEntry}. 1407 * 1408 * @param obj the object to compare 1409 * @return true if {@code obj} is equals to this or the referent of this 1410 * @see MethodType#equals(Object) 1411 * @see Object#equals(Object) 1412 */ 1413 @Override 1414 public boolean equals(Object obj) { 1415 Object mine = get(); 1416 if (obj instanceof WeakEntry) { 1417 Object that = ((WeakEntry) obj).get(); 1418 return (that == null || mine == null) ? (this == obj) : mine.equals(that); 1419 } 1420 return (mine == null) ? (obj == null) : mine.equals(obj); 1421 } 1422 1423 @Override 1424 public int hashCode() { 1425 return hashcode; 1426 } 1427 1428 } 1429 } 1430 1431 } 1432