1 /* 2 * Copyright (c) 2008, 2021, 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 * <p> 103 * <b><a id="descriptor">Nominal Descriptors</a></b> 104 * <p> 105 * A {@code MethodType} can be described in {@linkplain MethodTypeDesc nominal form} 106 * if and only if all of the parameter types and return type can be described 107 * with a {@link Class#describeConstable() nominal descriptor} represented by 108 * {@link ClassDesc}. If a method type can be described nominally, then: 109 * <ul> 110 * <li>The method type has a {@link MethodTypeDesc nominal descriptor} 111 * returned by {@link #describeConstable() MethodType::describeConstable}.</li> 112 * <li>The descriptor string returned by 113 * {@link #descriptorString() MethodType::descriptorString} or 114 * {@link #toMethodDescriptorString() MethodType::toMethodDescriptorString} 115 * for the method type is a method descriptor (JVMS {@jvms 4.3.3}).</li> 116 * </ul> 117 * <p> 118 * If any of the parameter types or return type cannot be described 119 * nominally, i.e. {@link Class#describeConstable() Class::describeConstable} 120 * returns an empty optional for that type, 121 * then the method type cannot be described nominally: 122 * <ul> 123 * <li>The method type has no {@link MethodTypeDesc nominal descriptor} and 124 * {@link #describeConstable() MethodType::describeConstable} returns 125 * an empty optional.</li> 126 * <li>The descriptor string returned by 127 * {@link #descriptorString() MethodType::descriptorString} or 128 * {@link #toMethodDescriptorString() MethodType::toMethodDescriptorString} 129 * for the method type is not a type descriptor.</li> 130 * </ul> 131 * 132 * @author John Rose, JSR 292 EG 133 * @since 1.7 134 */ 135 public final 136 class MethodType 137 implements Constable, 138 TypeDescriptor.OfMethod<Class<?>, MethodType>, 139 java.io.Serializable { 140 @java.io.Serial 141 private static final long serialVersionUID = 292L; // {rtype, {ptype...}} 142 143 // The rtype and ptypes fields define the structural identity of the method type: 144 private final @Stable Class<?> rtype; 145 private final @Stable Class<?>[] ptypes; 146 147 // The remaining fields are caches of various sorts: 148 private @Stable MethodTypeForm form; // erased form, plus cached data about primitives 149 private @Stable Object wrapAlt; // alternative wrapped/unwrapped version and 150 // private communication for readObject and readResolve 151 private @Stable Invokers invokers; // cache of handy higher-order adapters 152 private @Stable String methodDescriptor; // cache for toMethodDescriptorString 153 154 /** 155 * Constructor that performs no copying or validation. 156 * Should only be called from the factory method makeImpl 157 */ MethodType(Class<?> rtype, Class<?>[] ptypes)158 private MethodType(Class<?> rtype, Class<?>[] ptypes) { 159 this.rtype = rtype; 160 this.ptypes = ptypes; 161 } 162 form()163 /*trusted*/ MethodTypeForm form() { return form; } rtype()164 /*trusted*/ Class<?> rtype() { return rtype; } ptypes()165 /*trusted*/ Class<?>[] ptypes() { return ptypes; } 166 setForm(MethodTypeForm f)167 void setForm(MethodTypeForm f) { form = f; } 168 169 /** This number, mandated by the JVM spec as 255, 170 * is the maximum number of <em>slots</em> 171 * that any Java method can receive in its argument list. 172 * It limits both JVM signatures and method type objects. 173 * The longest possible invocation will look like 174 * {@code staticMethod(arg1, arg2, ..., arg255)} or 175 * {@code x.virtualMethod(arg1, arg2, ..., arg254)}. 176 */ 177 /*non-public*/ 178 static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec. 179 180 /** This number is the maximum arity of a method handle, 254. 181 * It is derived from the absolute JVM-imposed arity by subtracting one, 182 * which is the slot occupied by the method handle itself at the 183 * beginning of the argument list used to invoke the method handle. 184 * The longest possible invocation will look like 185 * {@code mh.invoke(arg1, arg2, ..., arg254)}. 186 */ 187 // Issue: Should we allow MH.invokeWithArguments to go to the full 255? 188 /*non-public*/ 189 static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver 190 191 /** This number is the maximum arity of a method handle invoker, 253. 192 * It is derived from the absolute JVM-imposed arity by subtracting two, 193 * which are the slots occupied by invoke method handle, and the 194 * target method handle, which are both at the beginning of the argument 195 * list used to invoke the target method handle. 196 * The longest possible invocation will look like 197 * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}. 198 */ 199 /*non-public*/ 200 static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker 201 202 /** Return number of extra slots (count of long/double args). */ checkPtypes(Class<?>[] ptypes)203 private static int checkPtypes(Class<?>[] ptypes) { 204 int slots = 0; 205 for (Class<?> ptype : ptypes) { 206 Objects.requireNonNull(ptype); 207 if (ptype == void.class) 208 throw newIllegalArgumentException("parameter type cannot be void"); 209 if (ptype == double.class || ptype == long.class) { 210 slots++; 211 } 212 } 213 checkSlotCount(ptypes.length + slots); 214 return slots; 215 } 216 217 static { 218 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work: assert(MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0219 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0); 220 } checkSlotCount(int count)221 static void checkSlotCount(int count) { 222 if ((count & MAX_JVM_ARITY) != count) 223 throw newIllegalArgumentException("bad parameter count "+count); 224 } newIndexOutOfBoundsException(Object num)225 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) { 226 if (num instanceof Integer) num = "bad index: "+num; 227 return new IndexOutOfBoundsException(num.toString()); 228 } 229 230 static final ConcurrentWeakInternSet<MethodType> internTable = new ConcurrentWeakInternSet<>(); 231 232 static final Class<?>[] NO_PTYPES = {}; 233 234 /** 235 * Finds or creates an instance of the given method type. 236 * @param rtype the return type 237 * @param ptypes the parameter types 238 * @return a method type with the given components 239 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null 240 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class} 241 */ methodType(Class<?> rtype, Class<?>[] ptypes)242 public static MethodType methodType(Class<?> rtype, Class<?>[] ptypes) { 243 return makeImpl(rtype, ptypes, false); 244 } 245 246 /** 247 * Finds or creates a method type with the given components. 248 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 249 * @param rtype the return type 250 * @param ptypes the parameter types 251 * @return a method type with the given components 252 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null 253 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class} 254 */ methodType(Class<?> rtype, List<Class<?>> ptypes)255 public static MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) { 256 boolean notrust = false; // random List impl. could return evil ptypes array 257 return makeImpl(rtype, listToArray(ptypes), notrust); 258 } 259 listToArray(List<Class<?>> ptypes)260 private static Class<?>[] listToArray(List<Class<?>> ptypes) { 261 // sanity check the size before the toArray call, since size might be huge 262 checkSlotCount(ptypes.size()); 263 return ptypes.toArray(NO_PTYPES); 264 } 265 266 /** 267 * Finds or creates a method type with the given components. 268 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 269 * The leading parameter type is prepended to the remaining array. 270 * @param rtype the return type 271 * @param ptype0 the first parameter type 272 * @param ptypes the remaining parameter types 273 * @return a method type with the given components 274 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null 275 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class} 276 */ methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes)277 public static MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) { 278 Class<?>[] ptypes1 = new Class<?>[1+ptypes.length]; 279 ptypes1[0] = ptype0; 280 System.arraycopy(ptypes, 0, ptypes1, 1, ptypes.length); 281 return makeImpl(rtype, ptypes1, true); 282 } 283 284 /** 285 * Finds or creates a method type with the given components. 286 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 287 * The resulting method has no parameter types. 288 * @param rtype the return type 289 * @return a method type with the given return value 290 * @throws NullPointerException if {@code rtype} is null 291 */ methodType(Class<?> rtype)292 public static MethodType methodType(Class<?> rtype) { 293 return makeImpl(rtype, NO_PTYPES, true); 294 } 295 296 /** 297 * Finds or creates a method type with the given components. 298 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 299 * The resulting method has the single given parameter type. 300 * @param rtype the return type 301 * @param ptype0 the parameter type 302 * @return a method type with the given return value and parameter type 303 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null 304 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class} 305 */ methodType(Class<?> rtype, Class<?> ptype0)306 public static MethodType methodType(Class<?> rtype, Class<?> ptype0) { 307 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true); 308 } 309 310 /** 311 * Finds or creates a method type with the given components. 312 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 313 * The resulting method has the same parameter types as {@code ptypes}, 314 * and the specified return type. 315 * @param rtype the return type 316 * @param ptypes the method type which supplies the parameter types 317 * @return a method type with the given components 318 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null 319 */ methodType(Class<?> rtype, MethodType ptypes)320 public static MethodType methodType(Class<?> rtype, MethodType ptypes) { 321 return makeImpl(rtype, ptypes.ptypes, true); 322 } 323 324 /** 325 * Sole factory method to find or create an interned method type. Will perform 326 * input validation on behalf of factory methods 327 * 328 * @param rtype desired return type 329 * @param ptypes desired parameter types 330 * @param trusted whether the ptypes can be used without cloning 331 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null 332 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class} 333 * @return the unique method type of the desired structure 334 */ 335 /*trusted*/ makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted)336 static MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) { 337 if (ptypes.length == 0) { 338 ptypes = NO_PTYPES; trusted = true; 339 } 340 MethodType primordialMT = new MethodType(rtype, ptypes); 341 MethodType mt = internTable.get(primordialMT); 342 if (mt != null) 343 return mt; 344 345 // promote the object to the Real Thing, and reprobe 346 Objects.requireNonNull(rtype); 347 if (trusted) { 348 MethodType.checkPtypes(ptypes); 349 mt = primordialMT; 350 } else { 351 // Make defensive copy then validate 352 ptypes = Arrays.copyOf(ptypes, ptypes.length); 353 MethodType.checkPtypes(ptypes); 354 mt = new MethodType(rtype, ptypes); 355 } 356 mt.form = MethodTypeForm.findForm(mt); 357 return internTable.add(mt); 358 } 359 private static final @Stable MethodType[] objectOnlyTypes = new MethodType[20]; 360 361 /** 362 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array. 363 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 364 * All parameters and the return type will be {@code Object}, 365 * except the final array parameter if any, which will be {@code Object[]}. 366 * @param objectArgCount number of parameters (excluding the final array parameter if any) 367 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]} 368 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments 369 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true) 370 * @see #genericMethodType(int) 371 */ genericMethodType(int objectArgCount, boolean finalArray)372 public static MethodType genericMethodType(int objectArgCount, boolean finalArray) { 373 MethodType mt; 374 checkSlotCount(objectArgCount); 375 int ivarargs = (!finalArray ? 0 : 1); 376 int ootIndex = objectArgCount*2 + ivarargs; 377 if (ootIndex < objectOnlyTypes.length) { 378 mt = objectOnlyTypes[ootIndex]; 379 if (mt != null) return mt; 380 } 381 Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs]; 382 Arrays.fill(ptypes, Object.class); 383 if (ivarargs != 0) ptypes[objectArgCount] = Object[].class; 384 mt = makeImpl(Object.class, ptypes, true); 385 if (ootIndex < objectOnlyTypes.length) { 386 objectOnlyTypes[ootIndex] = mt; // cache it here also! 387 } 388 return mt; 389 } 390 391 /** 392 * Finds or creates a method type whose components are all {@code Object}. 393 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 394 * All parameters and the return type will be Object. 395 * @param objectArgCount number of parameters 396 * @return a generally applicable method type, for all calls of the given argument count 397 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 398 * @see #genericMethodType(int, boolean) 399 */ genericMethodType(int objectArgCount)400 public static MethodType genericMethodType(int objectArgCount) { 401 return genericMethodType(objectArgCount, false); 402 } 403 404 /** 405 * Finds or creates a method type with a single different parameter type. 406 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 407 * @param num the index (zero-based) of the parameter type to change 408 * @param nptype a new parameter type to replace the old one with 409 * @return the same type, except with the selected parameter changed 410 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()} 411 * @throws IllegalArgumentException if {@code nptype} is {@code void.class} 412 * @throws NullPointerException if {@code nptype} is null 413 */ changeParameterType(int num, Class<?> nptype)414 public MethodType changeParameterType(int num, Class<?> nptype) { 415 if (parameterType(num) == nptype) return this; 416 Class<?>[] nptypes = ptypes.clone(); 417 nptypes[num] = nptype; 418 return makeImpl(rtype, nptypes, true); 419 } 420 421 /** 422 * Finds or creates a method type with additional parameter types. 423 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 424 * @param num the position (zero-based) of the inserted parameter type(s) 425 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 426 * @return the same type, except with the selected parameter(s) inserted 427 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()} 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 */ insertParameterTypes(int num, Class<?>... ptypesToInsert)432 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) { 433 int len = ptypes.length; 434 if (num < 0 || num > len) 435 throw newIndexOutOfBoundsException(num); 436 int ins = checkPtypes(ptypesToInsert); 437 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins); 438 int ilen = ptypesToInsert.length; 439 if (ilen == 0) return this; 440 Class<?>[] nptypes = new Class<?>[len + ilen]; 441 if (num > 0) { 442 System.arraycopy(ptypes, 0, nptypes, 0, num); 443 } 444 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen); 445 if (num < len) { 446 System.arraycopy(ptypes, num, nptypes, num+ilen, len-num); 447 } 448 return makeImpl(rtype, nptypes, true); 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 */ appendParameterTypes(Class<?>.... ptypesToInsert)460 public MethodType appendParameterTypes(Class<?>... ptypesToInsert) { 461 return insertParameterTypes(parameterCount(), ptypesToInsert); 462 } 463 464 /** 465 * Finds or creates a method type with additional parameter types. 466 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 467 * @param num the position (zero-based) of the inserted parameter type(s) 468 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 469 * @return the same type, except with the selected parameter(s) inserted 470 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()} 471 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 472 * or if the resulting method type would have more than 255 parameter slots 473 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 474 */ insertParameterTypes(int num, List<Class<?>> ptypesToInsert)475 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) { 476 return insertParameterTypes(num, listToArray(ptypesToInsert)); 477 } 478 479 /** 480 * Finds or creates a method type with additional parameter types. 481 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 482 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list 483 * @return the same type, except with the selected parameter(s) appended 484 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 485 * or if the resulting method type would have more than 255 parameter slots 486 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 487 */ appendParameterTypes(List<Class<?>> ptypesToInsert)488 public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) { 489 return insertParameterTypes(parameterCount(), ptypesToInsert); 490 } 491 492 /** 493 * Finds or creates a method type with modified parameter types. 494 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 495 * @param start the position (zero-based) of the first replaced parameter type(s) 496 * @param end the position (zero-based) after the last replaced parameter type(s) 497 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list 498 * @return the same type, except with the selected parameter(s) replaced 499 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()} 500 * or if {@code end} is negative or greater than {@code parameterCount()} 501 * or if {@code start} is greater than {@code end} 502 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} 503 * or if the resulting method type would have more than 255 parameter slots 504 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null 505 */ 506 /*non-public*/ replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert)507 MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) { 508 if (start == end) 509 return insertParameterTypes(start, ptypesToInsert); 510 int len = ptypes.length; 511 if (!(0 <= start && start <= end && end <= len)) 512 throw newIndexOutOfBoundsException("start="+start+" end="+end); 513 int ilen = ptypesToInsert.length; 514 if (ilen == 0) 515 return dropParameterTypes(start, end); 516 return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert); 517 } 518 519 /** Replace the last arrayLength parameter types with the component type of arrayType. 520 * @param arrayType any array type 521 * @param pos position at which to spread 522 * @param arrayLength the number of parameter types to change 523 * @return the resulting type 524 */ 525 /*non-public*/ asSpreaderType(Class<?> arrayType, int pos, int arrayLength)526 MethodType asSpreaderType(Class<?> arrayType, int pos, int arrayLength) { 527 assert(parameterCount() >= arrayLength); 528 int spreadPos = pos; 529 if (arrayLength == 0) return this; // nothing to change 530 if (arrayType == Object[].class) { 531 if (isGeneric()) return this; // nothing to change 532 if (spreadPos == 0) { 533 // no leading arguments to preserve; go generic 534 MethodType res = genericMethodType(arrayLength); 535 if (rtype != Object.class) { 536 res = res.changeReturnType(rtype); 537 } 538 return res; 539 } 540 } 541 Class<?> elemType = arrayType.getComponentType(); 542 assert(elemType != null); 543 for (int i = spreadPos; i < spreadPos + arrayLength; i++) { 544 if (ptypes[i] != elemType) { 545 Class<?>[] fixedPtypes = ptypes.clone(); 546 Arrays.fill(fixedPtypes, i, spreadPos + arrayLength, elemType); 547 return methodType(rtype, fixedPtypes); 548 } 549 } 550 return this; // arguments check out; no change 551 } 552 553 /** Return the leading parameter type, which must exist and be a reference. 554 * @return the leading parameter type, after error checks 555 */ 556 /*non-public*/ leadingReferenceParameter()557 Class<?> leadingReferenceParameter() { 558 Class<?> ptype; 559 if (ptypes.length == 0 || 560 (ptype = ptypes[0]).isPrimitive()) 561 throw newIllegalArgumentException("no leading reference parameter"); 562 return ptype; 563 } 564 565 /** Delete the last parameter type and replace it with arrayLength copies of the component type of arrayType. 566 * @param arrayType any array type 567 * @param pos position at which to insert parameters 568 * @param arrayLength the number of parameter types to insert 569 * @return the resulting type 570 */ 571 /*non-public*/ asCollectorType(Class<?> arrayType, int pos, int arrayLength)572 MethodType asCollectorType(Class<?> arrayType, int pos, int arrayLength) { 573 assert(parameterCount() >= 1); 574 assert(pos < ptypes.length); 575 assert(ptypes[pos].isAssignableFrom(arrayType)); 576 MethodType res; 577 if (arrayType == Object[].class) { 578 res = genericMethodType(arrayLength); 579 if (rtype != Object.class) { 580 res = res.changeReturnType(rtype); 581 } 582 } else { 583 Class<?> elemType = arrayType.getComponentType(); 584 assert(elemType != null); 585 res = methodType(rtype, Collections.nCopies(arrayLength, elemType)); 586 } 587 if (ptypes.length == 1) { 588 return res; 589 } else { 590 // insert after (if need be), then before 591 if (pos < ptypes.length - 1) { 592 res = res.insertParameterTypes(arrayLength, Arrays.copyOfRange(ptypes, pos + 1, ptypes.length)); 593 } 594 return res.insertParameterTypes(0, Arrays.copyOf(ptypes, pos)); 595 } 596 } 597 598 /** 599 * Finds or creates a method type with some parameter types omitted. 600 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 601 * @param start the index (zero-based) of the first parameter type to remove 602 * @param end the index (greater than {@code start}) of the first parameter type after not to remove 603 * @return the same type, except with the selected parameter(s) removed 604 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()} 605 * or if {@code end} is negative or greater than {@code parameterCount()} 606 * or if {@code start} is greater than {@code end} 607 */ 608 public MethodType dropParameterTypes(int start, int end) { 609 int len = ptypes.length; 610 if (!(0 <= start && start <= end && end <= len)) 611 throw newIndexOutOfBoundsException("start="+start+" end="+end); 612 if (start == end) return this; 613 Class<?>[] nptypes; 614 if (start == 0) { 615 if (end == len) { 616 // drop all parameters 617 nptypes = NO_PTYPES; 618 } else { 619 // drop initial parameter(s) 620 nptypes = Arrays.copyOfRange(ptypes, end, len); 621 } 622 } else { 623 if (end == len) { 624 // drop trailing parameter(s) 625 nptypes = Arrays.copyOfRange(ptypes, 0, start); 626 } else { 627 int tail = len - end; 628 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail); 629 System.arraycopy(ptypes, end, nptypes, start, tail); 630 } 631 } 632 return makeImpl(rtype, nptypes, true); 633 } 634 635 /** 636 * Finds or creates a method type with a different return type. 637 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 638 * @param nrtype a return parameter type to replace the old one with 639 * @return the same type, except with the return type change 640 * @throws NullPointerException if {@code nrtype} is null 641 */ 642 public MethodType changeReturnType(Class<?> nrtype) { 643 if (returnType() == nrtype) return this; 644 return makeImpl(nrtype, ptypes, true); 645 } 646 647 /** 648 * Reports if this type contains a primitive argument or return value. 649 * The return type {@code void} counts as a primitive. 650 * @return true if any of the types are primitives 651 */ 652 public boolean hasPrimitives() { 653 return form.hasPrimitives(); 654 } 655 656 /** 657 * Reports if this type contains a wrapper argument or return value. 658 * Wrappers are types which box primitive values, such as {@link Integer}. 659 * The reference type {@code java.lang.Void} counts as a wrapper, 660 * if it occurs as a return type. 661 * @return true if any of the types are wrappers 662 */ 663 public boolean hasWrappers() { 664 return unwrap() != this; 665 } 666 667 /** 668 * Erases all reference types to {@code Object}. 669 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 670 * All primitive types (including {@code void}) will remain unchanged. 671 * @return a version of the original type with all reference types replaced 672 */ 673 public MethodType erase() { 674 return form.erasedType(); 675 } 676 677 /** 678 * Erases all reference types to {@code Object}, and all subword types to {@code int}. 679 * This is the reduced type polymorphism used by private methods 680 * such as {@link MethodHandle#invokeBasic invokeBasic}. 681 * @return a version of the original type with all reference and subword types replaced 682 */ 683 /*non-public*/ 684 MethodType basicType() { 685 return form.basicType(); 686 } 687 688 private static final @Stable Class<?>[] METHOD_HANDLE_ARRAY 689 = new Class<?>[] { MethodHandle.class }; 690 691 /** 692 * @return a version of the original type with MethodHandle prepended as the first argument 693 */ 694 /*non-public*/ 695 MethodType invokerType() { 696 return insertParameterTypes(0, METHOD_HANDLE_ARRAY); 697 } 698 699 /** 700 * Converts all types, both reference and primitive, to {@code Object}. 701 * Convenience method for {@link #genericMethodType(int) genericMethodType}. 702 * The expression {@code type.wrap().erase()} produces the same value 703 * as {@code type.generic()}. 704 * @return a version of the original type with all types replaced 705 */ 706 public MethodType generic() { 707 return genericMethodType(parameterCount()); 708 } 709 710 /*non-public*/ 711 boolean isGeneric() { 712 return this == erase() && !hasPrimitives(); 713 } 714 715 /** 716 * Converts all primitive types to their corresponding wrapper types. 717 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 718 * All reference types (including wrapper types) will remain unchanged. 719 * A {@code void} return type is changed to the type {@code java.lang.Void}. 720 * The expression {@code type.wrap().erase()} produces the same value 721 * as {@code type.generic()}. 722 * @return a version of the original type with all primitive types replaced 723 */ 724 public MethodType wrap() { 725 return hasPrimitives() ? wrapWithPrims(this) : this; 726 } 727 728 /** 729 * Converts all wrapper types to their corresponding primitive types. 730 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 731 * All primitive types (including {@code void}) will remain unchanged. 732 * A return type of {@code java.lang.Void} is changed to {@code void}. 733 * @return a version of the original type with all wrapper types replaced 734 */ 735 public MethodType unwrap() { 736 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this); 737 return unwrapWithNoPrims(noprims); 738 } 739 740 private static MethodType wrapWithPrims(MethodType pt) { 741 assert(pt.hasPrimitives()); 742 MethodType wt = (MethodType)pt.wrapAlt; 743 if (wt == null) { 744 // fill in lazily 745 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP); 746 assert(wt != null); 747 pt.wrapAlt = wt; 748 } 749 return wt; 750 } 751 752 private static MethodType unwrapWithNoPrims(MethodType wt) { 753 assert(!wt.hasPrimitives()); 754 MethodType uwt = (MethodType)wt.wrapAlt; 755 if (uwt == null) { 756 // fill in lazily 757 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP); 758 if (uwt == null) 759 uwt = wt; // type has no wrappers or prims at all 760 wt.wrapAlt = uwt; 761 } 762 return uwt; 763 } 764 765 /** 766 * Returns the parameter type at the specified index, within this method type. 767 * @param num the index (zero-based) of the desired parameter type 768 * @return the selected parameter type 769 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()} 770 */ 771 public Class<?> parameterType(int num) { 772 return ptypes[num]; 773 } 774 /** 775 * Returns the number of parameter types in this method type. 776 * @return the number of parameter types 777 */ 778 public int parameterCount() { 779 return ptypes.length; 780 } 781 /** 782 * Returns the return type of this method type. 783 * @return the return type 784 */ 785 public Class<?> returnType() { 786 return rtype; 787 } 788 789 /** 790 * Presents the parameter types as a list (a convenience method). 791 * The list will be immutable. 792 * @return the parameter types (as an immutable list) 793 */ 794 public List<Class<?>> parameterList() { 795 return Collections.unmodifiableList(Arrays.asList(ptypes.clone())); 796 } 797 798 /** 799 * Returns the last parameter type of this method type. 800 * If this type has no parameters, the sentinel value 801 * {@code void.class} is returned instead. 802 * @apiNote 803 * <p> 804 * The sentinel value is chosen so that reflective queries can be 805 * made directly against the result value. 806 * The sentinel value cannot be confused with a real parameter, 807 * since {@code void} is never acceptable as a parameter type. 808 * For variable arity invocation modes, the expression 809 * {@link Class#getComponentType lastParameterType().getComponentType()} 810 * is useful to query the type of the "varargs" parameter. 811 * @return the last parameter type if any, else {@code void.class} 812 * @since 10 813 */ 814 public Class<?> lastParameterType() { 815 int len = ptypes.length; 816 return len == 0 ? void.class : ptypes[len-1]; 817 } 818 819 /** 820 * Presents the parameter types as an array (a convenience method). 821 * Changes to the array will not result in changes to the type. 822 * @return the parameter types (as a fresh copy if necessary) 823 */ 824 public Class<?>[] parameterArray() { 825 return ptypes.clone(); 826 } 827 828 /** 829 * Compares the specified object with this type for equality. 830 * That is, it returns {@code true} if and only if the specified object 831 * is also a method type with exactly the same parameters and return type. 832 * @param x object to compare 833 * @see Object#equals(Object) 834 */ 835 // This implementation may also return true if x is a WeakEntry containing 836 // a method type that is equal to this. This is an internal implementation 837 // detail to allow for faster method type lookups. 838 // See ConcurrentWeakInternSet.WeakEntry#equals(Object) 839 @Override 840 public boolean equals(Object x) { 841 if (this == x) { 842 return true; 843 } 844 if (x instanceof MethodType) { 845 return equals((MethodType)x); 846 } 847 if (x instanceof ConcurrentWeakInternSet.WeakEntry) { 848 Object o = ((ConcurrentWeakInternSet.WeakEntry)x).get(); 849 if (o instanceof MethodType) { 850 return equals((MethodType)o); 851 } 852 } 853 return false; 854 } 855 856 private boolean equals(MethodType that) { 857 return this.rtype == that.rtype 858 && Arrays.equals(this.ptypes, that.ptypes); 859 } 860 861 /** 862 * Returns the hash code value for this method type. 863 * It is defined to be the same as the hashcode of a List 864 * whose elements are the return type followed by the 865 * parameter types. 866 * @return the hash code value for this method type 867 * @see Object#hashCode() 868 * @see #equals(Object) 869 * @see List#hashCode() 870 */ 871 @Override 872 public int hashCode() { 873 int hashCode = 31 + rtype.hashCode(); 874 for (Class<?> ptype : ptypes) 875 hashCode = 31 * hashCode + ptype.hashCode(); 876 return hashCode; 877 } 878 879 /** 880 * Returns a string representation of the method type, 881 * of the form {@code "(PT0,PT1...)RT"}. 882 * The string representation of a method type is a 883 * parenthesis enclosed, comma separated list of type names, 884 * followed immediately by the return type. 885 * <p> 886 * Each type is represented by its 887 * {@link java.lang.Class#getSimpleName simple name}. 888 */ 889 @Override 890 public String toString() { 891 StringJoiner sj = new StringJoiner(",", "(", 892 ")" + rtype.getSimpleName()); 893 for (int i = 0; i < ptypes.length; i++) { 894 sj.add(ptypes[i].getSimpleName()); 895 } 896 return sj.toString(); 897 } 898 899 /** True if my parameter list is effectively identical to the given full list, 900 * after skipping the given number of my own initial parameters. 901 * In other words, after disregarding {@code skipPos} parameters, 902 * my remaining parameter list is no longer than the {@code fullList}, and 903 * is equal to the same-length initial sublist of {@code fullList}. 904 */ 905 /*non-public*/ 906 boolean effectivelyIdenticalParameters(int skipPos, List<Class<?>> fullList) { 907 int myLen = ptypes.length, fullLen = fullList.size(); 908 if (skipPos > myLen || myLen - skipPos > fullLen) 909 return false; 910 List<Class<?>> myList = Arrays.asList(ptypes); 911 if (skipPos != 0) { 912 myList = myList.subList(skipPos, myLen); 913 myLen -= skipPos; 914 } 915 if (fullLen == myLen) 916 return myList.equals(fullList); 917 else 918 return myList.equals(fullList.subList(0, myLen)); 919 } 920 921 /** True if the old return type can always be viewed (w/o casting) under new return type, 922 * and the new parameters can be viewed (w/o casting) under the old parameter types. 923 */ 924 /*non-public*/ 925 boolean isViewableAs(MethodType newType, boolean keepInterfaces) { 926 if (!VerifyType.isNullConversion(returnType(), newType.returnType(), keepInterfaces)) 927 return false; 928 if (form == newType.form && form.erasedType == this) 929 return true; // my reference parameters are all Object 930 if (ptypes == newType.ptypes) 931 return true; 932 int argc = parameterCount(); 933 if (argc != newType.parameterCount()) 934 return false; 935 for (int i = 0; i < argc; i++) { 936 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i), keepInterfaces)) 937 return false; 938 } 939 return true; 940 } 941 /*non-public*/ 942 boolean isConvertibleTo(MethodType newType) { 943 MethodTypeForm oldForm = this.form(); 944 MethodTypeForm newForm = newType.form(); 945 if (oldForm == newForm) 946 // same parameter count, same primitive/object mix 947 return true; 948 if (!canConvert(returnType(), newType.returnType())) 949 return false; 950 Class<?>[] srcTypes = newType.ptypes; 951 Class<?>[] dstTypes = ptypes; 952 if (srcTypes == dstTypes) 953 return true; 954 int argc; 955 if ((argc = srcTypes.length) != dstTypes.length) 956 return false; 957 if (argc <= 1) { 958 if (argc == 1 && !canConvert(srcTypes[0], dstTypes[0])) 959 return false; 960 return true; 961 } 962 if ((!oldForm.hasPrimitives() && oldForm.erasedType == this) || 963 (!newForm.hasPrimitives() && newForm.erasedType == newType)) { 964 // Somewhat complicated test to avoid a loop of 2 or more trips. 965 // If either type has only Object parameters, we know we can convert. 966 assert(canConvertParameters(srcTypes, dstTypes)); 967 return true; 968 } 969 return canConvertParameters(srcTypes, dstTypes); 970 } 971 972 /** Returns true if MHs.explicitCastArguments produces the same result as MH.asType. 973 * If the type conversion is impossible for either, the result should be false. 974 */ 975 /*non-public*/ 976 boolean explicitCastEquivalentToAsType(MethodType newType) { 977 if (this == newType) return true; 978 if (!explicitCastEquivalentToAsType(rtype, newType.rtype)) { 979 return false; 980 } 981 Class<?>[] srcTypes = newType.ptypes; 982 Class<?>[] dstTypes = ptypes; 983 if (dstTypes == srcTypes) { 984 return true; 985 } 986 assert(dstTypes.length == srcTypes.length); 987 for (int i = 0; i < dstTypes.length; i++) { 988 if (!explicitCastEquivalentToAsType(srcTypes[i], dstTypes[i])) { 989 return false; 990 } 991 } 992 return true; 993 } 994 995 /** Reports true if the src can be converted to the dst, by both asType and MHs.eCE, 996 * and with the same effect. 997 * MHs.eCA has the following "upgrades" to MH.asType: 998 * 1. interfaces are unchecked (that is, treated as if aliased to Object) 999 * Therefore, {@code Object->CharSequence} is possible in both cases but has different semantics 1000 * 2. the full matrix of primitive-to-primitive conversions is supported 1001 * Narrowing like {@code long->byte} and basic-typing like {@code boolean->int} 1002 * are not supported by asType, but anything supported by asType is equivalent 1003 * with MHs.eCE. 1004 * 3a. unboxing conversions can be followed by the full matrix of primitive conversions 1005 * 3b. unboxing of null is permitted (creates a zero primitive value) 1006 * Other than interfaces, reference-to-reference conversions are the same. 1007 * Boxing primitives to references is the same for both operators. 1008 */ 1009 private static boolean explicitCastEquivalentToAsType(Class<?> src, Class<?> dst) { 1010 if (src == dst || dst == Object.class || dst == void.class) return true; 1011 if (src.isPrimitive()) { 1012 // Could be a prim/prim conversion, where casting is a strict superset. 1013 // Or a boxing conversion, which is always to an exact wrapper class. 1014 return canConvert(src, dst); 1015 } else if (dst.isPrimitive()) { 1016 // Unboxing behavior is different between MHs.eCA & MH.asType (see 3b). 1017 return false; 1018 } else { 1019 // R->R always works, but we have to avoid a check-cast to an interface. 1020 return !dst.isInterface() || dst.isAssignableFrom(src); 1021 } 1022 } 1023 1024 private boolean canConvertParameters(Class<?>[] srcTypes, Class<?>[] dstTypes) { 1025 for (int i = 0; i < srcTypes.length; i++) { 1026 if (!canConvert(srcTypes[i], dstTypes[i])) { 1027 return false; 1028 } 1029 } 1030 return true; 1031 } 1032 1033 /*non-public*/ 1034 static boolean canConvert(Class<?> src, Class<?> dst) { 1035 // short-circuit a few cases: 1036 if (src == dst || src == Object.class || dst == Object.class) return true; 1037 // the remainder of this logic is documented in MethodHandle.asType 1038 if (src.isPrimitive()) { 1039 // can force void to an explicit null, a la reflect.Method.invoke 1040 // can also force void to a primitive zero, by analogy 1041 if (src == void.class) return true; //or !dst.isPrimitive()? 1042 Wrapper sw = Wrapper.forPrimitiveType(src); 1043 if (dst.isPrimitive()) { 1044 // P->P must widen 1045 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw); 1046 } else { 1047 // P->R must box and widen 1048 return dst.isAssignableFrom(sw.wrapperType()); 1049 } 1050 } else if (dst.isPrimitive()) { 1051 // any value can be dropped 1052 if (dst == void.class) return true; 1053 Wrapper dw = Wrapper.forPrimitiveType(dst); 1054 // R->P must be able to unbox (from a dynamically chosen type) and widen 1055 // For example: 1056 // Byte/Number/Comparable/Object -> dw:Byte -> byte. 1057 // Character/Comparable/Object -> dw:Character -> char 1058 // Boolean/Comparable/Object -> dw:Boolean -> boolean 1059 // This means that dw must be cast-compatible with src. 1060 if (src.isAssignableFrom(dw.wrapperType())) { 1061 return true; 1062 } 1063 // The above does not work if the source reference is strongly typed 1064 // to a wrapper whose primitive must be widened. For example: 1065 // Byte -> unbox:byte -> short/int/long/float/double 1066 // Character -> unbox:char -> int/long/float/double 1067 if (Wrapper.isWrapperType(src) && 1068 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) { 1069 // can unbox from src and then widen to dst 1070 return true; 1071 } 1072 // We have already covered cases which arise due to runtime unboxing 1073 // of a reference type which covers several wrapper types: 1074 // Object -> cast:Integer -> unbox:int -> long/float/double 1075 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double 1076 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a 1077 // subclass of Number which wraps a value that can convert to char. 1078 // Since there is none, we don't need an extra check here to cover char or boolean. 1079 return false; 1080 } else { 1081 // R->R always works, since null is always valid dynamically 1082 return true; 1083 } 1084 } 1085 1086 /// Queries which have to do with the bytecode architecture 1087 1088 /** Reports the number of JVM stack slots required to invoke a method 1089 * of this type. Note that (for historical reasons) the JVM requires 1090 * a second stack slot to pass long and double arguments. 1091 * So this method returns {@link #parameterCount() parameterCount} plus the 1092 * number of long and double parameters (if any). 1093 * <p> 1094 * This method is included for the benefit of applications that must 1095 * generate bytecodes that process method handles and invokedynamic. 1096 * @return the number of JVM stack slots for this type's parameters 1097 */ 1098 /*non-public*/ 1099 int parameterSlotCount() { 1100 return form.parameterSlotCount(); 1101 } 1102 1103 /*non-public*/ 1104 Invokers invokers() { 1105 Invokers inv = invokers; 1106 if (inv != null) return inv; 1107 invokers = inv = new Invokers(this); 1108 return inv; 1109 } 1110 1111 /** 1112 * Finds or creates an instance of a method type, given the spelling of its bytecode descriptor. 1113 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. 1114 * Any class or interface name embedded in the descriptor string will be 1115 * resolved by the given loader (or if it is null, on the system class loader). 1116 * <p> 1117 * Note that it is possible to encounter method types which cannot be 1118 * constructed by this method, because their component types are 1119 * not all reachable from a common class loader. 1120 * <p> 1121 * This method is included for the benefit of applications that must 1122 * generate bytecodes that process method handles and {@code invokedynamic}. 1123 * @param descriptor a bytecode-level type descriptor string "(T...)T" 1124 * @param loader the class loader in which to look up the types 1125 * @return a method type matching the bytecode-level type descriptor 1126 * @throws NullPointerException if the string is null 1127 * @throws IllegalArgumentException if the string is not well-formed 1128 * @throws TypeNotPresentException if a named type cannot be found 1129 * @throws SecurityException if the security manager is present and 1130 * {@code loader} is {@code null} and the caller does not have the 1131 * {@link RuntimePermission}{@code ("getClassLoader")} 1132 */ 1133 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader) 1134 throws IllegalArgumentException, TypeNotPresentException 1135 { 1136 if (loader == null) { 1137 @SuppressWarnings("removal") 1138 SecurityManager sm = System.getSecurityManager(); 1139 if (sm != null) { 1140 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION); 1141 } 1142 } 1143 return fromDescriptor(descriptor, 1144 (loader == null) ? ClassLoader.getSystemClassLoader() : loader); 1145 } 1146 1147 /** 1148 * Same as {@link #fromMethodDescriptorString(String, ClassLoader)}, but 1149 * {@code null} ClassLoader means the bootstrap loader is used here. 1150 * <p> 1151 * IMPORTANT: This method is preferable for JDK internal use as it more 1152 * correctly interprets {@code null} ClassLoader than 1153 * {@link #fromMethodDescriptorString(String, ClassLoader)}. 1154 * Use of this method also avoids early initialization issues when system 1155 * ClassLoader is not initialized yet. 1156 */ 1157 static MethodType fromDescriptor(String descriptor, ClassLoader loader) 1158 throws IllegalArgumentException, TypeNotPresentException 1159 { 1160 if (!descriptor.startsWith("(") || // also generates NPE if needed 1161 descriptor.indexOf(')') < 0 || 1162 descriptor.indexOf('.') >= 0) 1163 throw newIllegalArgumentException("not a method descriptor: "+descriptor); 1164 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader); 1165 Class<?> rtype = types.remove(types.size() - 1); 1166 Class<?>[] ptypes = listToArray(types); 1167 return makeImpl(rtype, ptypes, true); 1168 } 1169 1170 /** 1171 * Returns a descriptor string for the method type. This method 1172 * is equivalent to calling {@link #descriptorString() MethodType::descriptorString}. 1173 * 1174 * <p> 1175 * Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}. 1176 * Two distinct classes which share a common name but have different class loaders 1177 * will appear identical when viewed within descriptor strings. 1178 * <p> 1179 * This method is included for the benefit of applications that must 1180 * generate bytecodes that process method handles and {@code invokedynamic}. 1181 * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString}, 1182 * because the latter requires a suitable class loader argument. 1183 * @return the descriptor string for this method type 1184 * @jvms 4.3.3 Method Descriptors 1185 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a> 1186 */ 1187 public String toMethodDescriptorString() { 1188 String desc = methodDescriptor; 1189 if (desc == null) { 1190 desc = BytecodeDescriptor.unparseMethod(this.rtype, this.ptypes); 1191 methodDescriptor = desc; 1192 } 1193 return desc; 1194 } 1195 1196 /** 1197 * Returns a descriptor string for this method type. 1198 * 1199 * <p> 1200 * If this method type can be <a href="#descriptor">described nominally</a>, 1201 * then the result is a method type descriptor (JVMS {@jvms 4.3.3}). 1202 * {@link MethodTypeDesc MethodTypeDesc} for this method type 1203 * can be produced by calling {@link MethodTypeDesc#ofDescriptor(String) 1204 * MethodTypeDesc::ofDescriptor} with the result descriptor string. 1205 * <p> 1206 * If this method type cannot be <a href="#descriptor">described nominally</a> 1207 * and the result is a string of the form: 1208 * <blockquote>{@code "(<parameter-descriptors>)<return-descriptor>"}</blockquote> 1209 * where {@code <parameter-descriptors>} is the concatenation of the 1210 * {@linkplain Class#descriptorString() descriptor string} of all 1211 * of the parameter types and the {@linkplain Class#descriptorString() descriptor string} 1212 * of the return type. No {@link java.lang.constant.MethodTypeDesc MethodTypeDesc} 1213 * can be produced from the result string. 1214 * 1215 * @return the descriptor string for this method type 1216 * @since 12 1217 * @jvms 4.3.3 Method Descriptors 1218 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a> 1219 */ 1220 @Override 1221 public String descriptorString() { 1222 return toMethodDescriptorString(); 1223 } 1224 1225 /*non-public*/ 1226 static String toFieldDescriptorString(Class<?> cls) { 1227 return BytecodeDescriptor.unparse(cls); 1228 } 1229 1230 /** 1231 * Returns a nominal descriptor for this instance, if one can be 1232 * constructed, or an empty {@link Optional} if one cannot be. 1233 * 1234 * @return An {@link Optional} containing the resulting nominal descriptor, 1235 * or an empty {@link Optional} if one cannot be constructed. 1236 * @since 12 1237 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a> 1238 */ 1239 @Override 1240 public Optional<MethodTypeDesc> describeConstable() { 1241 try { 1242 return Optional.of(MethodTypeDesc.of(returnType().describeConstable().orElseThrow(), 1243 Stream.of(parameterArray()) 1244 .map(p -> p.describeConstable().orElseThrow()) 1245 .toArray(ClassDesc[]::new))); 1246 } 1247 catch (NoSuchElementException e) { 1248 return Optional.empty(); 1249 } 1250 } 1251 1252 /// Serialization. 1253 1254 /** 1255 * There are no serializable fields for {@code MethodType}. 1256 */ 1257 @java.io.Serial 1258 private static final java.io.ObjectStreamField[] serialPersistentFields = { }; 1259 1260 /** 1261 * Save the {@code MethodType} instance to a stream. 1262 * 1263 * @serialData 1264 * For portability, the serialized format does not refer to named fields. 1265 * Instead, the return type and parameter type arrays are written directly 1266 * from the {@code writeObject} method, using two calls to {@code s.writeObject} 1267 * as follows: 1268 * <blockquote><pre>{@code 1269 s.writeObject(this.returnType()); 1270 s.writeObject(this.parameterArray()); 1271 * }</pre></blockquote> 1272 * <p> 1273 * The deserialized field values are checked as if they were 1274 * provided to the factory method {@link #methodType(Class,Class[]) methodType}. 1275 * For example, null values, or {@code void} parameter types, 1276 * will lead to exceptions during deserialization. 1277 * @param s the stream to write the object to 1278 * @throws java.io.IOException if there is a problem writing the object 1279 */ 1280 @java.io.Serial 1281 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException { 1282 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array 1283 s.writeObject(returnType()); 1284 s.writeObject(parameterArray()); 1285 } 1286 1287 /** 1288 * Reconstitute the {@code MethodType} instance from a stream (that is, 1289 * deserialize it). 1290 * This instance is a scratch object with bogus final fields. 1291 * It provides the parameters to the factory method called by 1292 * {@link #readResolve readResolve}. 1293 * After that call it is discarded. 1294 * @param s the stream to read the object from 1295 * @throws java.io.IOException if there is a problem reading the object 1296 * @throws ClassNotFoundException if one of the component classes cannot be resolved 1297 * @see #readResolve 1298 * @see #writeObject 1299 */ 1300 @java.io.Serial 1301 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException { 1302 // Assign defaults in case this object escapes 1303 UNSAFE.putReference(this, OffsetHolder.rtypeOffset, void.class); 1304 UNSAFE.putReference(this, OffsetHolder.ptypesOffset, NO_PTYPES); 1305 1306 s.defaultReadObject(); // requires serialPersistentFields to be an empty array 1307 1308 Class<?> returnType = (Class<?>) s.readObject(); 1309 Class<?>[] parameterArray = (Class<?>[]) s.readObject(); 1310 1311 // Verify all operands, and make sure ptypes is unshared 1312 // Cache the new MethodType for readResolve 1313 wrapAlt = new MethodType[]{MethodType.methodType(returnType, parameterArray)}; 1314 } 1315 1316 // Support for resetting final fields while deserializing. Implement Holder 1317 // pattern to make the rarely needed offset calculation lazy. 1318 private static class OffsetHolder { 1319 static final long rtypeOffset 1320 = UNSAFE.objectFieldOffset(MethodType.class, "rtype"); 1321 1322 static final long ptypesOffset 1323 = UNSAFE.objectFieldOffset(MethodType.class, "ptypes"); 1324 } 1325 1326 /** 1327 * Resolves and initializes a {@code MethodType} object 1328 * after serialization. 1329 * @return the fully initialized {@code MethodType} object 1330 */ 1331 @java.io.Serial 1332 private Object readResolve() { 1333 // Do not use a trusted path for deserialization: 1334 // return makeImpl(rtype, ptypes, true); 1335 // Verify all operands, and make sure ptypes is unshared: 1336 // Return a new validated MethodType for the rtype and ptypes passed from readObject. 1337 MethodType mt = ((MethodType[])wrapAlt)[0]; 1338 wrapAlt = null; 1339 return mt; 1340 } 1341 1342 /** 1343 * Simple implementation of weak concurrent intern set. 1344 * 1345 * @param <T> interned type 1346 */ 1347 private static class ConcurrentWeakInternSet<T> { 1348 1349 private final ConcurrentMap<WeakEntry<T>, WeakEntry<T>> map; 1350 private final ReferenceQueue<T> stale; 1351 1352 public ConcurrentWeakInternSet() { 1353 this.map = new ConcurrentHashMap<>(512); 1354 this.stale = new ReferenceQueue<>(); 1355 } 1356 1357 /** 1358 * Get the existing interned element. 1359 * This method returns null if no element is interned. 1360 * 1361 * @param elem element to look up 1362 * @return the interned element 1363 */ 1364 public T get(T elem) { 1365 if (elem == null) throw new NullPointerException(); 1366 expungeStaleElements(); 1367 1368 WeakEntry<T> value = map.get(elem); 1369 if (value != null) { 1370 T res = value.get(); 1371 if (res != null) { 1372 return res; 1373 } 1374 } 1375 return null; 1376 } 1377 1378 /** 1379 * Interns the element. 1380 * Always returns non-null element, matching the one in the intern set. 1381 * Under the race against another add(), it can return <i>different</i> 1382 * element, if another thread beats us to interning it. 1383 * 1384 * @param elem element to add 1385 * @return element that was actually added 1386 */ 1387 public T add(T elem) { 1388 if (elem == null) throw new NullPointerException(); 1389 1390 // Playing double race here, and so spinloop is required. 1391 // First race is with two concurrent updaters. 1392 // Second race is with GC purging weak ref under our feet. 1393 // Hopefully, we almost always end up with a single pass. 1394 T interned; 1395 WeakEntry<T> e = new WeakEntry<>(elem, stale); 1396 do { 1397 expungeStaleElements(); 1398 WeakEntry<T> exist = map.putIfAbsent(e, e); 1399 interned = (exist == null) ? elem : exist.get(); 1400 } while (interned == null); 1401 return interned; 1402 } 1403 1404 private void expungeStaleElements() { 1405 Reference<? extends T> reference; 1406 while ((reference = stale.poll()) != null) { 1407 map.remove(reference); 1408 } 1409 } 1410 1411 private static class WeakEntry<T> extends WeakReference<T> { 1412 1413 public final int hashcode; 1414 1415 public WeakEntry(T key, ReferenceQueue<T> queue) { 1416 super(key, queue); 1417 hashcode = key.hashCode(); 1418 } 1419 1420 /** 1421 * This implementation returns {@code true} if {@code obj} is another 1422 * {@code WeakEntry} whose referent is equal to this referent, or 1423 * if {@code obj} is equal to the referent of this. This allows 1424 * lookups to be made without wrapping in a {@code WeakEntry}. 1425 * 1426 * @param obj the object to compare 1427 * @return true if {@code obj} is equal to this or the referent of this 1428 * @see MethodType#equals(Object) 1429 * @see Object#equals(Object) 1430 */ 1431 @Override 1432 public boolean equals(Object obj) { 1433 Object mine = get(); 1434 if (obj instanceof WeakEntry) { 1435 Object that = ((WeakEntry) obj).get(); 1436 return (that == null || mine == null) ? (this == obj) : mine.equals(that); 1437 } 1438 return (mine == null) ? (obj == null) : mine.equals(obj); 1439 } 1440 1441 @Override 1442 public int hashCode() { 1443 return hashcode; 1444 } 1445 1446 } 1447 } 1448 1449 } 1450