1 /*
2 * Copyright (c) 2008, 2024, 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.function.Supplier;
37 import java.util.HashMap;
38 import java.util.Iterator;
39 import java.util.List;
40 import java.util.Map;
41 import java.util.NoSuchElementException;
42 import java.util.Objects;
43 import java.util.Optional;
44 import java.util.StringJoiner;
45 import java.util.concurrent.ConcurrentHashMap;
46 import java.util.concurrent.ConcurrentMap;
47 import java.util.stream.Stream;
48
49 import jdk.internal.misc.CDS;
50 import jdk.internal.util.ReferencedKeySet;
51 import jdk.internal.util.ReferenceKey;
52 import jdk.internal.vm.annotation.Stable;
53 import sun.invoke.util.BytecodeDescriptor;
54 import sun.invoke.util.VerifyType;
55 import sun.invoke.util.Wrapper;
56 import sun.security.util.SecurityConstants;
57
58 import static java.lang.invoke.MethodHandleStatics.UNSAFE;
59 import static java.lang.invoke.MethodHandleStatics.newIllegalArgumentException;
60
61 /**
62 * A method type represents the arguments and return type accepted and
63 * returned by a method handle, or the arguments and return type passed
64 * and expected by a method handle caller. Method types must be properly
65 * matched between a method handle and all its callers,
66 * and the JVM's operations enforce this matching at, specifically
67 * during calls to {@link MethodHandle#invokeExact MethodHandle.invokeExact}
68 * and {@link MethodHandle#invoke MethodHandle.invoke}, and during execution
69 * of {@code invokedynamic} instructions.
70 * <p>
71 * The structure is a return type accompanied by any number of parameter types.
72 * The types (primitive, {@code void}, and reference) are represented by {@link Class} objects.
73 * (For ease of exposition, we treat {@code void} as if it were a type.
74 * In fact, it denotes the absence of a return type.)
75 * <p>
76 * All instances of {@code MethodType} are immutable.
77 * Two instances are completely interchangeable if they compare equal.
78 * Equality depends on pairwise correspondence of the return and parameter types and on nothing else.
79 * <p>
80 * This type can be created only by factory methods.
81 * All factory methods may cache values, though caching is not guaranteed.
82 * Some factory methods are static, while others are virtual methods which
83 * modify precursor method types, e.g., by changing a selected parameter.
84 * <p>
85 * Factory methods which operate on groups of parameter types
86 * are systematically presented in two versions, so that both Java arrays and
87 * Java lists can be used to work with groups of parameter types.
88 * The query methods {@code parameterArray} and {@code parameterList}
89 * also provide a choice between arrays and lists.
90 * <p>
91 * {@code MethodType} objects are sometimes derived from bytecode instructions
92 * such as {@code invokedynamic}, specifically from the type descriptor strings associated
93 * with the instructions in a class file's constant pool.
94 * <p>
95 * Like classes and strings, method types can also be represented directly
96 * in a class file's constant pool as constants.
97 * A method type may be loaded by an {@code ldc} instruction which refers
98 * to a suitable {@code CONSTANT_MethodType} constant pool entry.
99 * The entry refers to a {@code CONSTANT_Utf8} spelling for the descriptor string.
100 * (For full details on method type constants, see sections {@jvms
101 * 4.4.8} and {@jvms 5.4.3.5} of the Java Virtual Machine
102 * Specification.)
103 * <p>
104 * When the JVM materializes a {@code MethodType} from a descriptor string,
105 * all classes named in the descriptor must be accessible, and will be loaded.
106 * (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.)
107 * This loading may occur at any time before the {@code MethodType} object is first derived.
108 * <p>
109 * <b><a id="descriptor">Nominal Descriptors</a></b>
110 * <p>
111 * A {@code MethodType} can be described in {@linkplain MethodTypeDesc nominal form}
112 * if and only if all of the parameter types and return type can be described
113 * with a {@link Class#describeConstable() nominal descriptor} represented by
114 * {@link ClassDesc}. If a method type can be described nominally, then:
115 * <ul>
116 * <li>The method type has a {@link MethodTypeDesc nominal descriptor}
117 * returned by {@link #describeConstable() MethodType::describeConstable}.</li>
118 * <li>The descriptor string returned by
119 * {@link #descriptorString() MethodType::descriptorString} or
120 * {@link #toMethodDescriptorString() MethodType::toMethodDescriptorString}
121 * for the method type is a method descriptor (JVMS {@jvms 4.3.3}).</li>
122 * </ul>
123 * <p>
124 * If any of the parameter types or return type cannot be described
125 * nominally, i.e. {@link Class#describeConstable() Class::describeConstable}
126 * returns an empty optional for that type,
127 * then the method type cannot be described nominally:
128 * <ul>
129 * <li>The method type has no {@link MethodTypeDesc nominal descriptor} and
130 * {@link #describeConstable() MethodType::describeConstable} returns
131 * an empty optional.</li>
132 * <li>The descriptor string returned by
133 * {@link #descriptorString() MethodType::descriptorString} or
134 * {@link #toMethodDescriptorString() MethodType::toMethodDescriptorString}
135 * for the method type is not a type descriptor.</li>
136 * </ul>
137 *
138 * @author John Rose, JSR 292 EG
139 * @since 1.7
140 */
141 public final
142 class MethodType
143 implements Constable,
144 TypeDescriptor.OfMethod<Class<?>, MethodType>,
145 java.io.Serializable {
146 @java.io.Serial
147 private static final long serialVersionUID = 292L; // {rtype, {ptype...}}
148
149 // The rtype and ptypes fields define the structural identity of the method type:
150 private final @Stable Class<?> rtype;
151 private final @Stable Class<?>[] ptypes;
152
153 // The remaining fields are caches of various sorts:
154 private @Stable MethodTypeForm form; // erased form, plus cached data about primitives
155 private @Stable Object wrapAlt; // alternative wrapped/unwrapped version and
156 // private communication for readObject and readResolve
157 private @Stable Invokers invokers; // cache of handy higher-order adapters
158 private @Stable String methodDescriptor; // cache for toMethodDescriptorString
159
160 private final boolean checkArchivable = CDS.isDumpingArchive();
161 /**
162 * Constructor that performs no copying or validation.
163 * Should only be called from the factory method makeImpl
164 */
165 private MethodType(Class<?> rtype, Class<?>[] ptypes) {
166 if (checkArchivable) {
167 MethodHandleNatives.checkArchivable(rtype);
168 for (var p : ptypes) {
169 MethodHandleNatives.checkArchivable(p);
170 }
171 }
172
173 this.rtype = rtype;
174 this.ptypes = ptypes;
175 }
176
177 /*trusted*/ MethodTypeForm form() { return form; }
178 /*trusted*/ Class<?> rtype() { return rtype; }
179 /*trusted*/ Class<?>[] ptypes() { return ptypes; }
180
181 void setForm(MethodTypeForm f) { form = f; }
182
183 /** This number, mandated by the JVM spec as 255,
184 * is the maximum number of <em>slots</em>
185 * that any Java method can receive in its argument list.
186 * It limits both JVM signatures and method type objects.
187 * The longest possible invocation will look like
188 * {@code staticMethod(arg1, arg2, ..., arg255)} or
189 * {@code x.virtualMethod(arg1, arg2, ..., arg254)}.
190 */
191 /*non-public*/
192 static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec.
193
194 /** This number is the maximum arity of a method handle, 254.
195 * It is derived from the absolute JVM-imposed arity by subtracting one,
196 * which is the slot occupied by the method handle itself at the
197 * beginning of the argument list used to invoke the method handle.
198 * The longest possible invocation will look like
199 * {@code mh.invoke(arg1, arg2, ..., arg254)}.
200 */
201 // Issue: Should we allow MH.invokeWithArguments to go to the full 255?
202 /*non-public*/
203 static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver
204
205 /** This number is the maximum arity of a method handle invoker, 253.
206 * It is derived from the absolute JVM-imposed arity by subtracting two,
207 * which are the slots occupied by invoke method handle, and the
208 * target method handle, which are both at the beginning of the argument
209 * list used to invoke the target method handle.
210 * The longest possible invocation will look like
211 * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}.
212 */
213 /*non-public*/
214 static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker
215
216 /** Return number of extra slots (count of long/double args). */
217 private static int checkPtypes(Class<?>[] ptypes) {
218 int slots = 0;
219 for (Class<?> ptype : ptypes) {
220 Objects.requireNonNull(ptype);
221 if (ptype == void.class)
222 throw newIllegalArgumentException("parameter type cannot be void");
223 if (ptype == double.class || ptype == long.class) {
224 slots++;
225 }
226 }
227 checkSlotCount(ptypes.length + slots);
228 return slots;
229 }
230
231 static {
232 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work:
233 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0);
234 }
235 static void checkSlotCount(int count) {
236 if ((count & MAX_JVM_ARITY) != count)
237 throw newIllegalArgumentException("bad parameter count "+count);
238 }
239 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) {
240 if (num instanceof Integer) num = "bad index: "+num;
241 return new IndexOutOfBoundsException(num.toString());
242 }
243
244 static final ReferencedKeySet<MethodType> internTable =
245 ReferencedKeySet.create(false, true, new Supplier<>() {
246 @Override
247 public Map<ReferenceKey<MethodType>, ReferenceKey<MethodType>> get() {
248 return new ConcurrentHashMap<>(512);
249 }
250 });
251
252 static final Class<?>[] NO_PTYPES = {};
253
254 /**
255 * Finds or creates an instance of the given method type.
256 * @param rtype the return type
257 * @param ptypes the parameter types
258 * @return a method type with the given components
259 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
260 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
261 */
262 public static MethodType methodType(Class<?> rtype, Class<?>[] ptypes) {
263 return methodType(rtype, ptypes, false);
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 * @param rtype the return type
270 * @param ptypes the parameter types
271 * @return a method type with the given components
272 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
273 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
274 */
275 public static MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) {
276 boolean notrust = false; // random List impl. could return evil ptypes array
277 return methodType(rtype, listToArray(ptypes), notrust);
278 }
279
280 private static Class<?>[] listToArray(List<Class<?>> ptypes) {
281 // sanity check the size before the toArray call, since size might be huge
282 checkSlotCount(ptypes.size());
283 return ptypes.toArray(NO_PTYPES);
284 }
285
286 /**
287 * Finds or creates a method type with the given components.
288 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
289 * The leading parameter type is prepended to the remaining array.
290 * @param rtype the return type
291 * @param ptype0 the first parameter type
292 * @param ptypes the remaining parameter types
293 * @return a method type with the given components
294 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null
295 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class}
296 */
297 public static MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) {
298 int len = ptypes.length;
299 if (rtype == Object.class && ptype0 == Object.class) {
300 if (len == 0) {
301 return genericMethodType(1, false);
302 }
303 if (isAllObject(ptypes, len - 1)) {
304 Class<?> lastParam = ptypes[len - 1];
305 if (lastParam == Object.class) {
306 return genericMethodType(len + 1, false);
307 } else if (lastParam == Object[].class) {
308 return genericMethodType(len, true);
309 }
310 }
311 }
312 Class<?>[] ptypes1 = new Class<?>[1 + len];
313 ptypes1[0] = ptype0;
314 System.arraycopy(ptypes, 0, ptypes1, 1, len);
315 return makeImpl(rtype, ptypes1, true);
316 }
317
318 /**
319 * Finds or creates a method type with the given components.
320 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
321 * The resulting method has no parameter types.
322 * @param rtype the return type
323 * @return a method type with the given return value
324 * @throws NullPointerException if {@code rtype} is null
325 */
326 public static MethodType methodType(Class<?> rtype) {
327 if (rtype == Object.class) {
328 return genericMethodType(0, false);
329 }
330 return makeImpl(rtype, NO_PTYPES, true);
331 }
332
333 /**
334 * Finds or creates a method type with the given components.
335 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
336 * The resulting method has the single given parameter type.
337 * @param rtype the return type
338 * @param ptype0 the parameter type
339 * @return a method type with the given return value and parameter type
340 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null
341 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class}
342 */
343 public static MethodType methodType(Class<?> rtype, Class<?> ptype0) {
344 if (rtype == Object.class) {
345 if (ptype0 == Object.class) {
346 return genericMethodType(1, false);
347 } else if (ptype0 == Object[].class) {
348 return genericMethodType(0, true);
349 }
350 }
351 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true);
352 }
353
354 /**
355 * Finds or creates a method type with the given components.
356 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
357 * The resulting method has the same parameter types as {@code ptypes},
358 * and the specified return type.
359 * @param rtype the return type
360 * @param ptypes the method type which supplies the parameter types
361 * @return a method type with the given components
362 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null
363 */
364 public static MethodType methodType(Class<?> rtype, MethodType ptypes) {
365 return methodType(rtype, ptypes.ptypes, true);
366 }
367
368 private static boolean isAllObject(Class<?>[] ptypes, int to) {
369 for (int i = 0; i < to; i++) {
370 if (ptypes[i] != Object.class) {
371 return false;
372 }
373 }
374 return true;
375 }
376
377 /*trusted*/
378 static MethodType methodType(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
379 if (rtype == Object.class) {
380 int last = ptypes.length - 1;
381 if (last < 0) {
382 return genericMethodType(0, false);
383 }
384 if (isAllObject(ptypes, last)) {
385 Class<?> lastParam = ptypes[last];
386 if (lastParam == Object.class) {
387 return genericMethodType(last + 1, false);
388 } else if (lastParam == Object[].class) {
389 return genericMethodType(last, true);
390 }
391 }
392 }
393 return makeImpl(rtype, ptypes, trusted);
394 }
395
396 /**
397 * Sole factory method to find or create an interned method type. Will perform
398 * input validation on behalf of factory methods
399 *
400 * @param rtype desired return type
401 * @param ptypes desired parameter types
402 * @param trusted whether the ptypes can be used without cloning
403 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
404 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
405 * @return the unique method type of the desired structure
406 */
407 private static MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
408 if (ptypes.length == 0) {
409 ptypes = NO_PTYPES; trusted = true;
410 }
411 MethodType primordialMT = new MethodType(rtype, ptypes);
412 if (AOTHolder.archivedMethodTypes != null) {
413 MethodType mt = AOTHolder.archivedMethodTypes.get(primordialMT);
414 if (mt != null) {
415 return mt;
416 }
417 }
418
419 MethodType mt = internTable.get(primordialMT);
420 if (mt != null)
421 return mt;
422
423 // promote the object to the Real Thing, and reprobe
424 Objects.requireNonNull(rtype);
425 if (trusted) {
426 MethodType.checkPtypes(ptypes);
427 mt = primordialMT;
428 } else {
429 // Make defensive copy then validate
430 ptypes = Arrays.copyOf(ptypes, ptypes.length);
431 MethodType.checkPtypes(ptypes);
432 mt = new MethodType(rtype, ptypes);
433 }
434 mt.form = MethodTypeForm.findForm(mt);
435 return internTable.intern(mt);
436 }
437
438 static class AOTHolder {
439 private static final @Stable MethodType[] objectOnlyTypes = new MethodType[20];
440 private static @Stable HashMap<MethodType,MethodType> archivedMethodTypes;
441 }
442
443 /**
444 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array.
445 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
446 * All parameters and the return type will be {@code Object},
447 * except the final array parameter if any, which will be {@code Object[]}.
448 * @param objectArgCount number of parameters (excluding the final array parameter if any)
449 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]}
450 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments
451 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true)
452 * @see #genericMethodType(int)
453 */
454 public static MethodType genericMethodType(int objectArgCount, boolean finalArray) {
455 MethodType mt;
456 checkSlotCount(objectArgCount);
457 int ivarargs = (!finalArray ? 0 : 1);
458 int ootIndex = objectArgCount*2 + ivarargs;
459 if (ootIndex < AOTHolder.objectOnlyTypes.length) {
460 mt = AOTHolder.objectOnlyTypes[ootIndex];
461 if (mt != null) return mt;
462 }
463 Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs];
464 Arrays.fill(ptypes, Object.class);
465 if (ivarargs != 0) ptypes[objectArgCount] = Object[].class;
466 mt = makeImpl(Object.class, ptypes, true);
467 if (ootIndex < AOTHolder.objectOnlyTypes.length) {
468 AOTHolder.objectOnlyTypes[ootIndex] = mt; // cache it here also!
469 }
470 return mt;
471 }
472
473 /**
474 * Finds or creates a method type whose components are all {@code Object}.
475 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
476 * All parameters and the return type will be Object.
477 * @param objectArgCount number of parameters
478 * @return a generally applicable method type, for all calls of the given argument count
479 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255
480 * @see #genericMethodType(int, boolean)
481 */
482 public static MethodType genericMethodType(int objectArgCount) {
483 return genericMethodType(objectArgCount, false);
484 }
485
486 /**
487 * Finds or creates a method type with a single different parameter type.
488 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
489 * @param num the index (zero-based) of the parameter type to change
490 * @param nptype a new parameter type to replace the old one with
491 * @return the same type, except with the selected parameter changed
492 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
493 * @throws IllegalArgumentException if {@code nptype} is {@code void.class}
494 * @throws NullPointerException if {@code nptype} is null
495 */
496 public MethodType changeParameterType(int num, Class<?> nptype) {
497 if (parameterType(num) == nptype) return this;
498 Class<?>[] nptypes = ptypes.clone();
499 nptypes[num] = nptype;
500 return makeImpl(rtype, nptypes, true);
501 }
502
503 /**
504 * Finds or creates a method type with additional parameter types.
505 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
506 * @param num the position (zero-based) of the inserted parameter type(s)
507 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
508 * @return the same type, except with the selected parameter(s) inserted
509 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
510 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
511 * or if the resulting method type would have more than 255 parameter slots
512 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
513 */
514 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) {
515 int len = ptypes.length;
516 if (num < 0 || num > len)
517 throw newIndexOutOfBoundsException(num);
518 int ins = checkPtypes(ptypesToInsert);
519 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins);
520 int ilen = ptypesToInsert.length;
521 if (ilen == 0) return this;
522 Class<?>[] nptypes = new Class<?>[len + ilen];
523 if (num > 0) {
524 System.arraycopy(ptypes, 0, nptypes, 0, num);
525 }
526 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen);
527 if (num < len) {
528 System.arraycopy(ptypes, num, nptypes, num+ilen, len-num);
529 }
530 return makeImpl(rtype, nptypes, true);
531 }
532
533 /**
534 * Finds or creates a method type with additional parameter types.
535 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
536 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
537 * @return the same type, except with the selected parameter(s) appended
538 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
539 * or if the resulting method type would have more than 255 parameter slots
540 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
541 */
542 public MethodType appendParameterTypes(Class<?>... ptypesToInsert) {
543 return insertParameterTypes(parameterCount(), ptypesToInsert);
544 }
545
546 /**
547 * Finds or creates a method type with additional parameter types.
548 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
549 * @param num the position (zero-based) of the inserted parameter type(s)
550 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
551 * @return the same type, except with the selected parameter(s) inserted
552 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
553 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
554 * or if the resulting method type would have more than 255 parameter slots
555 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
556 */
557 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) {
558 return insertParameterTypes(num, listToArray(ptypesToInsert));
559 }
560
561 /**
562 * Finds or creates a method type with additional parameter types.
563 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
564 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
565 * @return the same type, except with the selected parameter(s) appended
566 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
567 * or if the resulting method type would have more than 255 parameter slots
568 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
569 */
570 public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) {
571 return insertParameterTypes(parameterCount(), ptypesToInsert);
572 }
573
574 /**
575 * Finds or creates a method type with modified parameter types.
576 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
577 * @param start the position (zero-based) of the first replaced parameter type(s)
578 * @param end the position (zero-based) after the last replaced parameter type(s)
579 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
580 * @return the same type, except with the selected parameter(s) replaced
581 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
582 * or if {@code end} is negative or greater than {@code parameterCount()}
583 * or if {@code start} is greater than {@code end}
584 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
585 * or if the resulting method type would have more than 255 parameter slots
586 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
587 */
588 /*non-public*/
589 MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) {
590 if (start == end)
591 return insertParameterTypes(start, ptypesToInsert);
592 int len = ptypes.length;
593 if (!(0 <= start && start <= end && end <= len))
594 throw newIndexOutOfBoundsException("start="+start+" end="+end);
595 int ilen = ptypesToInsert.length;
596 if (ilen == 0)
597 return dropParameterTypes(start, end);
598 return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert);
599 }
600
601 /** Replace the last arrayLength parameter types with the component type of arrayType.
602 * @param arrayType any array type
603 * @param pos position at which to spread
604 * @param arrayLength the number of parameter types to change
605 * @return the resulting type
606 */
607 /*non-public*/
608 MethodType asSpreaderType(Class<?> arrayType, int pos, int arrayLength) {
609 assert(parameterCount() >= arrayLength);
610 int spreadPos = pos;
611 if (arrayLength == 0) return this; // nothing to change
612 if (arrayType == Object[].class) {
613 if (isGeneric()) return this; // nothing to change
614 if (spreadPos == 0) {
615 // no leading arguments to preserve; go generic
616 MethodType res = genericMethodType(arrayLength);
617 if (rtype != Object.class) {
618 res = res.changeReturnType(rtype);
619 }
620 return res;
621 }
622 }
623 Class<?> elemType = arrayType.getComponentType();
624 assert(elemType != null);
625 for (int i = spreadPos; i < spreadPos + arrayLength; i++) {
626 if (ptypes[i] != elemType) {
627 Class<?>[] fixedPtypes = ptypes.clone();
628 Arrays.fill(fixedPtypes, i, spreadPos + arrayLength, elemType);
629 return methodType(rtype, fixedPtypes);
630 }
631 }
632 return this; // arguments check out; no change
633 }
634
635 /** Return the leading parameter type, which must exist and be a reference.
636 * @return the leading parameter type, after error checks
637 */
638 /*non-public*/
639 Class<?> leadingReferenceParameter() {
640 Class<?> ptype;
641 if (ptypes.length == 0 ||
642 (ptype = ptypes[0]).isPrimitive())
643 throw newIllegalArgumentException("no leading reference parameter");
644 return ptype;
645 }
646
647 /** Delete the last parameter type and replace it with arrayLength copies of the component type of arrayType.
648 * @param arrayType any array type
649 * @param pos position at which to insert parameters
650 * @param arrayLength the number of parameter types to insert
651 * @return the resulting type
652 */
653 /*non-public*/
654 MethodType asCollectorType(Class<?> arrayType, int pos, int arrayLength) {
655 assert(parameterCount() >= 1);
656 assert(pos < ptypes.length);
657 assert(ptypes[pos].isAssignableFrom(arrayType));
658 MethodType res;
659 if (arrayType == Object[].class) {
660 res = genericMethodType(arrayLength);
661 if (rtype != Object.class) {
662 res = res.changeReturnType(rtype);
663 }
664 } else {
665 Class<?> elemType = arrayType.getComponentType();
666 assert(elemType != null);
667 res = methodType(rtype, Collections.nCopies(arrayLength, elemType));
668 }
669 if (ptypes.length == 1) {
670 return res;
671 } else {
672 // insert after (if need be), then before
673 if (pos < ptypes.length - 1) {
674 res = res.insertParameterTypes(arrayLength, Arrays.copyOfRange(ptypes, pos + 1, ptypes.length));
675 }
676 return res.insertParameterTypes(0, Arrays.copyOf(ptypes, pos));
677 }
678 }
679
680 /**
681 * Finds or creates a method type with some parameter types omitted.
682 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
683 * @param start the index (zero-based) of the first parameter type to remove
684 * @param end the index (greater than {@code start}) of the first parameter type after not to remove
685 * @return the same type, except with the selected parameter(s) removed
686 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
687 * or if {@code end} is negative or greater than {@code parameterCount()}
688 * or if {@code start} is greater than {@code end}
689 */
690 public MethodType dropParameterTypes(int start, int end) {
691 int len = ptypes.length;
692 if (!(0 <= start && start <= end && end <= len))
693 throw newIndexOutOfBoundsException("start="+start+" end="+end);
694 if (start == end) return this;
695 Class<?>[] nptypes;
696 if (start == 0) {
697 if (end == len) {
698 // drop all parameters
699 nptypes = NO_PTYPES;
700 } else {
701 // drop initial parameter(s)
702 nptypes = Arrays.copyOfRange(ptypes, end, len);
703 }
704 } else {
705 if (end == len) {
706 // drop trailing parameter(s)
707 nptypes = Arrays.copyOfRange(ptypes, 0, start);
708 } else {
709 int tail = len - end;
710 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail);
711 System.arraycopy(ptypes, end, nptypes, start, tail);
712 }
713 }
714 return methodType(rtype, nptypes, true);
715 }
716
717 /**
718 * Finds or creates a method type with a different return type.
719 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
720 * @param nrtype a return parameter type to replace the old one with
721 * @return the same type, except with the return type change
722 * @throws NullPointerException if {@code nrtype} is null
723 */
724 public MethodType changeReturnType(Class<?> nrtype) {
725 if (returnType() == nrtype) return this;
726 return methodType(nrtype, ptypes, true);
727 }
728
729 /**
730 * Reports if this type contains a primitive argument or return value.
731 * The return type {@code void} counts as a primitive.
732 * @return true if any of the types are primitives
733 */
734 public boolean hasPrimitives() {
735 return form.hasPrimitives();
736 }
737
738 /**
739 * Reports if this type contains a wrapper argument or return value.
740 * Wrappers are types which box primitive values, such as {@link Integer}.
741 * The reference type {@code java.lang.Void} counts as a wrapper,
742 * if it occurs as a return type.
743 * @return true if any of the types are wrappers
744 */
745 public boolean hasWrappers() {
746 return unwrap() != this;
747 }
748
749 /**
750 * Erases all reference types to {@code Object}.
751 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
752 * All primitive types (including {@code void}) will remain unchanged.
753 * @return a version of the original type with all reference types replaced
754 */
755 public MethodType erase() {
756 return form.erasedType();
757 }
758
759 /**
760 * Erases all reference types to {@code Object}, and all subword types to {@code int}.
761 * This is the reduced type polymorphism used by private methods
762 * such as {@link MethodHandle#invokeBasic invokeBasic}.
763 * @return a version of the original type with all reference and subword types replaced
764 */
765 /*non-public*/
766 MethodType basicType() {
767 return form.basicType();
768 }
769
770 private static final @Stable Class<?>[] METHOD_HANDLE_ARRAY
771 = new Class<?>[] { MethodHandle.class };
772
773 /**
774 * @return a version of the original type with MethodHandle prepended as the first argument
775 */
776 /*non-public*/
777 MethodType invokerType() {
778 return insertParameterTypes(0, METHOD_HANDLE_ARRAY);
779 }
780
781 /**
782 * Converts all types, both reference and primitive, to {@code Object}.
783 * Convenience method for {@link #genericMethodType(int) genericMethodType}.
784 * The expression {@code type.wrap().erase()} produces the same value
785 * as {@code type.generic()}.
786 * @return a version of the original type with all types replaced
787 */
788 public MethodType generic() {
789 return genericMethodType(parameterCount());
790 }
791
792 /*non-public*/
793 boolean isGeneric() {
794 return this == erase() && !hasPrimitives();
795 }
796
797 /**
798 * Converts all primitive types to their corresponding wrapper types.
799 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
800 * All reference types (including wrapper types) will remain unchanged.
801 * A {@code void} return type is changed to the type {@code java.lang.Void}.
802 * The expression {@code type.wrap().erase()} produces the same value
803 * as {@code type.generic()}.
804 * @return a version of the original type with all primitive types replaced
805 */
806 public MethodType wrap() {
807 return hasPrimitives() ? wrapWithPrims(this) : this;
808 }
809
810 /**
811 * Converts all wrapper types to their corresponding primitive types.
812 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
813 * All primitive types (including {@code void}) will remain unchanged.
814 * A return type of {@code java.lang.Void} is changed to {@code void}.
815 * @return a version of the original type with all wrapper types replaced
816 */
817 public MethodType unwrap() {
818 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this);
819 return unwrapWithNoPrims(noprims);
820 }
821
822 private static MethodType wrapWithPrims(MethodType pt) {
823 assert(pt.hasPrimitives());
824 MethodType wt = (MethodType)pt.wrapAlt;
825 if (wt == null) {
826 // fill in lazily
827 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP);
828 assert(wt != null);
829 pt.wrapAlt = wt;
830 }
831 return wt;
832 }
833
834 private static MethodType unwrapWithNoPrims(MethodType wt) {
835 assert(!wt.hasPrimitives());
836 MethodType uwt = (MethodType)wt.wrapAlt;
837 if (uwt == null) {
838 // fill in lazily
839 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP);
840 if (uwt == null)
841 uwt = wt; // type has no wrappers or prims at all
842 wt.wrapAlt = uwt;
843 }
844 return uwt;
845 }
846
847 /**
848 * Returns the parameter type at the specified index, within this method type.
849 * @param num the index (zero-based) of the desired parameter type
850 * @return the selected parameter type
851 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
852 */
853 public Class<?> parameterType(int num) {
854 return ptypes[num];
855 }
856 /**
857 * Returns the number of parameter types in this method type.
858 * @return the number of parameter types
859 */
860 public int parameterCount() {
861 return ptypes.length;
862 }
863 /**
864 * Returns the return type of this method type.
865 * @return the return type
866 */
867 public Class<?> returnType() {
868 return rtype;
869 }
870
871 /**
872 * Presents the parameter types as a list (a convenience method).
873 * The list will be immutable.
874 * @return the parameter types (as an immutable list)
875 */
876 public List<Class<?>> parameterList() {
877 return List.of(ptypes);
878 }
879
880 /**
881 * Returns the last parameter type of this method type.
882 * If this type has no parameters, the sentinel value
883 * {@code void.class} is returned instead.
884 * @apiNote
885 * <p>
886 * The sentinel value is chosen so that reflective queries can be
887 * made directly against the result value.
888 * The sentinel value cannot be confused with a real parameter,
889 * since {@code void} is never acceptable as a parameter type.
890 * For variable arity invocation modes, the expression
891 * {@link Class#getComponentType lastParameterType().getComponentType()}
892 * is useful to query the type of the "varargs" parameter.
893 * @return the last parameter type if any, else {@code void.class}
894 * @since 10
895 */
896 public Class<?> lastParameterType() {
897 int len = ptypes.length;
898 return len == 0 ? void.class : ptypes[len-1];
899 }
900
901 /**
902 * Presents the parameter types as an array (a convenience method).
903 * Changes to the array will not result in changes to the type.
904 * @return the parameter types (as a fresh copy if necessary)
905 */
906 public Class<?>[] parameterArray() {
907 return ptypes.clone();
908 }
909
910 /**
911 * Compares the specified object with this type for equality.
912 * That is, it returns {@code true} if and only if the specified object
913 * is also a method type with exactly the same parameters and return type.
914 * @param x object to compare
915 * @see Object#equals(Object)
916 */
917 @Override
918 public boolean equals(Object x) {
919 if (this == x) {
920 return true;
921 }
922 if (x instanceof MethodType mt) {
923 return equals(mt);
924 }
925 return false;
926 }
927
928 private boolean equals(MethodType that) {
929 return this.rtype == that.rtype
930 && Arrays.equals(this.ptypes, that.ptypes);
931 }
932
933 /**
934 * Returns the hash code value for this method type.
935 * It is defined to be the same as the hashcode of a List
936 * whose elements are the return type followed by the
937 * parameter types.
938 * @return the hash code value for this method type
939 * @see Object#hashCode()
940 * @see #equals(Object)
941 * @see List#hashCode()
942 */
943 @Override
944 public int hashCode() {
945 int hashCode = 31 + rtype.hashCode();
946 for (Class<?> ptype : ptypes)
947 hashCode = 31 * hashCode + ptype.hashCode();
948 return hashCode;
949 }
950
951 /**
952 * Returns a string representation of the method type,
953 * of the form {@code "(PT0,PT1...)RT"}.
954 * The string representation of a method type is a
955 * parenthesis enclosed, comma separated list of type names,
956 * followed immediately by the return type.
957 * <p>
958 * Each type is represented by its
959 * {@link java.lang.Class#getSimpleName simple name}.
960 */
961 @Override
962 public String toString() {
963 StringJoiner sj = new StringJoiner(",", "(",
964 ")" + rtype.getSimpleName());
965 for (int i = 0; i < ptypes.length; i++) {
966 sj.add(ptypes[i].getSimpleName());
967 }
968 return sj.toString();
969 }
970
971 /** True if my parameter list is effectively identical to the given full list,
972 * after skipping the given number of my own initial parameters.
973 * In other words, after disregarding {@code skipPos} parameters,
974 * my remaining parameter list is no longer than the {@code fullList}, and
975 * is equal to the same-length initial sublist of {@code fullList}.
976 */
977 /*non-public*/
978 boolean effectivelyIdenticalParameters(int skipPos, List<Class<?>> fullList) {
979 int myLen = ptypes.length, fullLen = fullList.size();
980 if (skipPos > myLen || myLen - skipPos > fullLen)
981 return false;
982 List<Class<?>> myList = Arrays.asList(ptypes);
983 if (skipPos != 0) {
984 myList = myList.subList(skipPos, myLen);
985 myLen -= skipPos;
986 }
987 if (fullLen == myLen)
988 return myList.equals(fullList);
989 else
990 return myList.equals(fullList.subList(0, myLen));
991 }
992
993 /** True if the old return type can always be viewed (w/o casting) under new return type,
994 * and the new parameters can be viewed (w/o casting) under the old parameter types.
995 */
996 /*non-public*/
997 boolean isViewableAs(MethodType newType, boolean keepInterfaces) {
998 if (!VerifyType.isNullConversion(returnType(), newType.returnType(), keepInterfaces))
999 return false;
1000 if (form == newType.form && form.erasedType == this)
1001 return true; // my reference parameters are all Object
1002 if (ptypes == newType.ptypes)
1003 return true;
1004 int argc = parameterCount();
1005 if (argc != newType.parameterCount())
1006 return false;
1007 for (int i = 0; i < argc; i++) {
1008 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i), keepInterfaces))
1009 return false;
1010 }
1011 return true;
1012 }
1013 /*non-public*/
1014 boolean isConvertibleTo(MethodType newType) {
1015 MethodTypeForm oldForm = this.form();
1016 MethodTypeForm newForm = newType.form();
1017 if (oldForm == newForm)
1018 // same parameter count, same primitive/object mix
1019 return true;
1020 if (!canConvert(returnType(), newType.returnType()))
1021 return false;
1022 Class<?>[] srcTypes = newType.ptypes;
1023 Class<?>[] dstTypes = ptypes;
1024 if (srcTypes == dstTypes)
1025 return true;
1026 int argc;
1027 if ((argc = srcTypes.length) != dstTypes.length)
1028 return false;
1029 if (argc <= 1) {
1030 if (argc == 1 && !canConvert(srcTypes[0], dstTypes[0]))
1031 return false;
1032 return true;
1033 }
1034 if ((!oldForm.hasPrimitives() && oldForm.erasedType == this) ||
1035 (!newForm.hasPrimitives() && newForm.erasedType == newType)) {
1036 // Somewhat complicated test to avoid a loop of 2 or more trips.
1037 // If either type has only Object parameters, we know we can convert.
1038 assert(canConvertParameters(srcTypes, dstTypes));
1039 return true;
1040 }
1041 return canConvertParameters(srcTypes, dstTypes);
1042 }
1043
1044 /** Returns true if MHs.explicitCastArguments produces the same result as MH.asType.
1045 * If the type conversion is impossible for either, the result should be false.
1046 */
1047 /*non-public*/
1048 boolean explicitCastEquivalentToAsType(MethodType newType) {
1049 if (this == newType) return true;
1050 if (!explicitCastEquivalentToAsType(rtype, newType.rtype)) {
1051 return false;
1052 }
1053 Class<?>[] srcTypes = newType.ptypes;
1054 Class<?>[] dstTypes = ptypes;
1055 if (dstTypes == srcTypes) {
1056 return true;
1057 }
1058 assert(dstTypes.length == srcTypes.length);
1059 for (int i = 0; i < dstTypes.length; i++) {
1060 if (!explicitCastEquivalentToAsType(srcTypes[i], dstTypes[i])) {
1061 return false;
1062 }
1063 }
1064 return true;
1065 }
1066
1067 /** Reports true if the src can be converted to the dst, by both asType and MHs.eCE,
1068 * and with the same effect.
1069 * MHs.eCA has the following "upgrades" to MH.asType:
1070 * 1. interfaces are unchecked (that is, treated as if aliased to Object)
1071 * Therefore, {@code Object->CharSequence} is possible in both cases but has different semantics
1072 * 2. the full matrix of primitive-to-primitive conversions is supported
1073 * Narrowing like {@code long->byte} and basic-typing like {@code boolean->int}
1074 * are not supported by asType, but anything supported by asType is equivalent
1075 * with MHs.eCE.
1076 * 3a. unboxing conversions can be followed by the full matrix of primitive conversions
1077 * 3b. unboxing of null is permitted (creates a zero primitive value)
1078 * Other than interfaces, reference-to-reference conversions are the same.
1079 * Boxing primitives to references is the same for both operators.
1080 */
1081 private static boolean explicitCastEquivalentToAsType(Class<?> src, Class<?> dst) {
1082 if (src == dst || dst == Object.class || dst == void.class) return true;
1083 if (src.isPrimitive()) {
1084 // Could be a prim/prim conversion, where casting is a strict superset.
1085 // Or a boxing conversion, which is always to an exact wrapper class.
1086 return canConvert(src, dst);
1087 } else if (dst.isPrimitive()) {
1088 // Unboxing behavior is different between MHs.eCA & MH.asType (see 3b).
1089 return false;
1090 } else {
1091 // R->R always works, but we have to avoid a check-cast to an interface.
1092 return !dst.isInterface() || dst.isAssignableFrom(src);
1093 }
1094 }
1095
1096 private boolean canConvertParameters(Class<?>[] srcTypes, Class<?>[] dstTypes) {
1097 for (int i = 0; i < srcTypes.length; i++) {
1098 if (!canConvert(srcTypes[i], dstTypes[i])) {
1099 return false;
1100 }
1101 }
1102 return true;
1103 }
1104
1105 /*non-public*/
1106 static boolean canConvert(Class<?> src, Class<?> dst) {
1107 // short-circuit a few cases:
1108 if (src == dst || src == Object.class || dst == Object.class) return true;
1109 // the remainder of this logic is documented in MethodHandle.asType
1110 if (src.isPrimitive()) {
1111 // can force void to an explicit null, a la reflect.Method.invoke
1112 // can also force void to a primitive zero, by analogy
1113 if (src == void.class) return true; //or !dst.isPrimitive()?
1114 Wrapper sw = Wrapper.forPrimitiveType(src);
1115 if (dst.isPrimitive()) {
1116 // P->P must widen
1117 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw);
1118 } else {
1119 // P->R must box and widen
1120 return dst.isAssignableFrom(sw.wrapperType());
1121 }
1122 } else if (dst.isPrimitive()) {
1123 // any value can be dropped
1124 if (dst == void.class) return true;
1125 Wrapper dw = Wrapper.forPrimitiveType(dst);
1126 // R->P must be able to unbox (from a dynamically chosen type) and widen
1127 // For example:
1128 // Byte/Number/Comparable/Object -> dw:Byte -> byte.
1129 // Character/Comparable/Object -> dw:Character -> char
1130 // Boolean/Comparable/Object -> dw:Boolean -> boolean
1131 // This means that dw must be cast-compatible with src.
1132 if (src.isAssignableFrom(dw.wrapperType())) {
1133 return true;
1134 }
1135 // The above does not work if the source reference is strongly typed
1136 // to a wrapper whose primitive must be widened. For example:
1137 // Byte -> unbox:byte -> short/int/long/float/double
1138 // Character -> unbox:char -> int/long/float/double
1139 if (Wrapper.isWrapperType(src) &&
1140 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) {
1141 // can unbox from src and then widen to dst
1142 return true;
1143 }
1144 // We have already covered cases which arise due to runtime unboxing
1145 // of a reference type which covers several wrapper types:
1146 // Object -> cast:Integer -> unbox:int -> long/float/double
1147 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double
1148 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a
1149 // subclass of Number which wraps a value that can convert to char.
1150 // Since there is none, we don't need an extra check here to cover char or boolean.
1151 return false;
1152 } else {
1153 // R->R always works, since null is always valid dynamically
1154 return true;
1155 }
1156 }
1157
1158 //--- Queries which have to do with the bytecode architecture
1159
1160 /** Reports the number of JVM stack slots required to invoke a method
1161 * of this type. Note that (for historical reasons) the JVM requires
1162 * a second stack slot to pass long and double arguments.
1163 * So this method returns {@link #parameterCount() parameterCount} plus the
1164 * number of long and double parameters (if any).
1165 * <p>
1166 * This method is included for the benefit of applications that must
1167 * generate bytecodes that process method handles and invokedynamic.
1168 * @return the number of JVM stack slots for this type's parameters
1169 */
1170 /*non-public*/
1171 int parameterSlotCount() {
1172 return form.parameterSlotCount();
1173 }
1174
1175 /*non-public*/
1176 Invokers invokers() {
1177 Invokers inv = invokers;
1178 if (inv != null) return inv;
1179 invokers = inv = new Invokers(this);
1180 return inv;
1181 }
1182
1183 /**
1184 * Finds or creates an instance of a method type of the given method descriptor
1185 * (JVMS {@jvms 4.3.3}). This method is a convenience method for
1186 * {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
1187 * Any class or interface name embedded in the descriptor string will be
1188 * resolved by the given loader (or if it is {@code null}, on the system class loader).
1189 *
1190 * @apiNote
1191 * It is possible to encounter method types that have valid descriptors but
1192 * cannot be constructed by this method, because their component types are
1193 * not visible from a common class loader.
1194 * <p>
1195 * This method is included for the benefit of applications that must
1196 * generate bytecodes that process method handles and {@code invokedynamic}.
1197 * @param descriptor a method descriptor string
1198 * @param loader the class loader in which to look up the types
1199 * @return a method type of the given method descriptor
1200 * @throws NullPointerException if the string is {@code null}
1201 * @throws IllegalArgumentException if the string is not a method descriptor
1202 * @throws TypeNotPresentException if a named type cannot be found
1203 * @throws SecurityException if the security manager is present and
1204 * {@code loader} is {@code null} and the caller does not have the
1205 * {@link RuntimePermission}{@code ("getClassLoader")}
1206 * @jvms 4.3.3 Method Descriptors
1207 */
1208 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader)
1209 throws IllegalArgumentException, TypeNotPresentException
1210 {
1211 if (loader == null) {
1212 @SuppressWarnings("removal")
1213 SecurityManager sm = System.getSecurityManager();
1214 if (sm != null) {
1215 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
1216 }
1217 }
1218 return fromDescriptor(descriptor,
1219 (loader == null) ? ClassLoader.getSystemClassLoader() : loader);
1220 }
1221
1222 /**
1223 * Same as {@link #fromMethodDescriptorString(String, ClassLoader)}, but
1224 * {@code null} ClassLoader means the bootstrap loader is used here.
1225 * <p>
1226 * IMPORTANT: This method is preferable for JDK internal use as it more
1227 * correctly interprets {@code null} ClassLoader than
1228 * {@link #fromMethodDescriptorString(String, ClassLoader)}.
1229 * Use of this method also avoids early initialization issues when system
1230 * ClassLoader is not initialized yet.
1231 */
1232 static MethodType fromDescriptor(String descriptor, ClassLoader loader)
1233 throws IllegalArgumentException, TypeNotPresentException
1234 {
1235 if (!descriptor.startsWith("(") || // also generates NPE if needed
1236 descriptor.indexOf(')') < 0 ||
1237 descriptor.indexOf('.') >= 0)
1238 throw newIllegalArgumentException("not a method descriptor: "+descriptor);
1239 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader);
1240 Class<?> rtype = types.remove(types.size() - 1);
1241 Class<?>[] ptypes = listToArray(types);
1242 return methodType(rtype, ptypes, true);
1243 }
1244
1245 /**
1246 * {@return the descriptor string for this method type} This method
1247 * is equivalent to calling {@link #descriptorString() MethodType::descriptorString}.
1248 *
1249 * @apiNote
1250 * This is not a strict inverse of {@link #fromMethodDescriptorString
1251 * fromMethodDescriptorString} which requires a method type descriptor
1252 * (JVMS {@jvms 4.3.3}) and a suitable class loader argument.
1253 * Two distinct {@code MethodType} objects can have an identical
1254 * descriptor string as distinct classes can have the same name
1255 * but different class loaders.
1256 *
1257 * <p>
1258 * This method is included for the benefit of applications that must
1259 * generate bytecodes that process method handles and {@code invokedynamic}.
1260 * @jvms 4.3.3 Method Descriptors
1261 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
1262 */
1263 public String toMethodDescriptorString() {
1264 String desc = methodDescriptor;
1265 if (desc == null) {
1266 desc = BytecodeDescriptor.unparseMethod(this.rtype, this.ptypes);
1267 methodDescriptor = desc;
1268 }
1269 return desc;
1270 }
1271
1272 /**
1273 * {@return the descriptor string for this method type}
1274 *
1275 * <p>
1276 * If this method type can be {@linkplain ##descriptor described nominally},
1277 * then the result is a method type descriptor (JVMS {@jvms 4.3.3}).
1278 * {@link MethodTypeDesc MethodTypeDesc} for this method type
1279 * can be produced by calling {@link MethodTypeDesc#ofDescriptor(String)
1280 * MethodTypeDesc::ofDescriptor} with the result descriptor string.
1281 * <p>
1282 * If this method type cannot be {@linkplain ##descriptor described nominally}
1283 * and the result is a string of the form:
1284 * <blockquote>{@code "(<parameter-descriptors>)<return-descriptor>"}</blockquote>
1285 * where {@code <parameter-descriptors>} is the concatenation of the
1286 * {@linkplain Class#descriptorString() descriptor string} of all
1287 * of the parameter types and the {@linkplain Class#descriptorString() descriptor string}
1288 * of the return type. No {@link java.lang.constant.MethodTypeDesc MethodTypeDesc}
1289 * can be produced from the result string.
1290 *
1291 * @since 12
1292 * @jvms 4.3.3 Method Descriptors
1293 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
1294 */
1295 @Override
1296 public String descriptorString() {
1297 return toMethodDescriptorString();
1298 }
1299
1300 /*non-public*/
1301 static String toFieldDescriptorString(Class<?> cls) {
1302 return BytecodeDescriptor.unparse(cls);
1303 }
1304
1305 /**
1306 * Returns a nominal descriptor for this instance, if one can be
1307 * constructed, or an empty {@link Optional} if one cannot be.
1308 *
1309 * @return An {@link Optional} containing the resulting nominal descriptor,
1310 * or an empty {@link Optional} if one cannot be constructed.
1311 * @since 12
1312 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
1313 */
1314 @Override
1315 public Optional<MethodTypeDesc> describeConstable() {
1316 var retDesc = returnType().describeConstable();
1317 if (retDesc.isEmpty())
1318 return Optional.empty();
1319
1320 if (parameterCount() == 0)
1321 return Optional.of(MethodTypeDesc.of(retDesc.get()));
1322
1323 var params = new ClassDesc[parameterCount()];
1324 for (int i = 0; i < params.length; i++) {
1325 var paramDesc = parameterType(i).describeConstable();
1326 if (paramDesc.isEmpty())
1327 return Optional.empty();
1328 params[i] = paramDesc.get();
1329 }
1330 return Optional.of(MethodTypeDesc.of(retDesc.get(), params));
1331 }
1332
1333 //--- Serialization.
1334
1335 /**
1336 * There are no serializable fields for {@code MethodType}.
1337 */
1338 @java.io.Serial
1339 private static final java.io.ObjectStreamField[] serialPersistentFields = { };
1340
1341 /**
1342 * Save the {@code MethodType} instance to a stream.
1343 *
1344 * @serialData
1345 * For portability, the serialized format does not refer to named fields.
1346 * Instead, the return type and parameter type arrays are written directly
1347 * from the {@code writeObject} method, using two calls to {@code s.writeObject}
1348 * as follows:
1349 * <blockquote><pre>{@code
1350 s.writeObject(this.returnType());
1351 s.writeObject(this.parameterArray());
1352 * }</pre></blockquote>
1353 * <p>
1354 * The deserialized field values are checked as if they were
1355 * provided to the factory method {@link #methodType(Class,Class[]) methodType}.
1356 * For example, null values, or {@code void} parameter types,
1357 * will lead to exceptions during deserialization.
1358 * @param s the stream to write the object to
1359 * @throws java.io.IOException if there is a problem writing the object
1360 */
1361 @java.io.Serial
1362 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
1363 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array
1364 s.writeObject(returnType());
1365 s.writeObject(parameterArray());
1366 }
1367
1368 /**
1369 * Reconstitute the {@code MethodType} instance from a stream (that is,
1370 * deserialize it).
1371 * This instance is a scratch object with bogus final fields.
1372 * It provides the parameters to the factory method called by
1373 * {@link #readResolve readResolve}.
1374 * After that call it is discarded.
1375 * @param s the stream to read the object from
1376 * @throws java.io.IOException if there is a problem reading the object
1377 * @throws ClassNotFoundException if one of the component classes cannot be resolved
1378 * @see #readResolve
1379 * @see #writeObject
1380 */
1381 @java.io.Serial
1382 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
1383 // Assign defaults in case this object escapes
1384 UNSAFE.putReference(this, OffsetHolder.rtypeOffset, void.class);
1385 UNSAFE.putReference(this, OffsetHolder.ptypesOffset, NO_PTYPES);
1386
1387 s.defaultReadObject(); // requires serialPersistentFields to be an empty array
1388
1389 Class<?> returnType = (Class<?>) s.readObject();
1390 Class<?>[] parameterArray = (Class<?>[]) s.readObject();
1391
1392 // Verify all operands, and make sure ptypes is unshared
1393 // Cache the new MethodType for readResolve
1394 wrapAlt = new MethodType[]{MethodType.methodType(returnType, parameterArray)};
1395 }
1396
1397 // Support for resetting final fields while deserializing. Implement Holder
1398 // pattern to make the rarely needed offset calculation lazy.
1399 private static class OffsetHolder {
1400 static final long rtypeOffset
1401 = UNSAFE.objectFieldOffset(MethodType.class, "rtype");
1402
1403 static final long ptypesOffset
1404 = UNSAFE.objectFieldOffset(MethodType.class, "ptypes");
1405 }
1406
1407 /**
1408 * Resolves and initializes a {@code MethodType} object
1409 * after serialization.
1410 * @return the fully initialized {@code MethodType} object
1411 */
1412 @java.io.Serial
1413 private Object readResolve() {
1414 // Do not use a trusted path for deserialization:
1415 // return makeImpl(rtype, ptypes, true);
1416 // Verify all operands, and make sure ptypes is unshared:
1417 // Return a new validated MethodType for the rtype and ptypes passed from readObject.
1418 MethodType mt = ((MethodType[])wrapAlt)[0];
1419 wrapAlt = null;
1420 return mt;
1421 }
1422
1423 static HashMap<MethodType,MethodType> copyInternTable() {
1424 HashMap<MethodType,MethodType> copy = new HashMap<>();
1425
1426 for (Iterator<MethodType> i = internTable.iterator(); i.hasNext(); ) {
1427 MethodType t = i.next();
1428 if (canBeArchived(t)) {
1429 copy.put(t, t);
1430 }
1431 }
1432
1433 return copy;
1434 }
1435
1436 static boolean canBeArchived(MethodType t) {
1437 if (t.form == null) { // FIXME why?
1438 return false;
1439 } else {
1440 return true;
1441 }
1442 }
1443
1444 // This is called from C code.
1445 static void createArchivedObjects() {
1446 for (int i = 0; i < AOTHolder.objectOnlyTypes.length; i++) {
1447 MethodType t = AOTHolder.objectOnlyTypes[i];
1448 if (t != null && !canBeArchived(t)) {
1449 AOTHolder.objectOnlyTypes[i] = null; // FIXME why?
1450 }
1451 }
1452
1453 AOTHolder.archivedMethodTypes = copyInternTable();
1454 }
1455 }