1 /*
2 * Copyright (c) 2008, 2023, 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.ArrayList;
36 import java.util.Collections;
37 import java.util.function.Supplier;
38 import java.util.HashMap;
39 import java.util.Iterator;
40 import java.util.List;
41 import java.util.Map;
42 import java.util.NoSuchElementException;
43 import java.util.Objects;
44 import java.util.Optional;
45 import java.util.StringJoiner;
46 import java.util.concurrent.ConcurrentHashMap;
47 import java.util.concurrent.ConcurrentMap;
48 import java.util.stream.Stream;
49
50 import jdk.internal.misc.CDS;
51 import jdk.internal.util.ReferencedKeySet;
52 import jdk.internal.util.ReferenceKey;
53 import jdk.internal.vm.annotation.Stable;
54 import sun.invoke.util.BytecodeDescriptor;
55 import sun.invoke.util.VerifyType;
56 import sun.invoke.util.Wrapper;
57 import sun.security.util.SecurityConstants;
58
59 import static java.lang.invoke.MethodHandleStatics.UNSAFE;
60 import static java.lang.invoke.MethodHandleStatics.newIllegalArgumentException;
61
62 /**
63 * A method type represents the arguments and return type accepted and
64 * returned by a method handle, or the arguments and return type passed
65 * and expected by a method handle caller. Method types must be properly
66 * matched between a method handle and all its callers,
67 * and the JVM's operations enforce this matching at, specifically
68 * during calls to {@link MethodHandle#invokeExact MethodHandle.invokeExact}
69 * and {@link MethodHandle#invoke MethodHandle.invoke}, and during execution
70 * of {@code invokedynamic} instructions.
71 * <p>
72 * The structure is a return type accompanied by any number of parameter types.
73 * The types (primitive, {@code void}, and reference) are represented by {@link Class} objects.
74 * (For ease of exposition, we treat {@code void} as if it were a type.
75 * In fact, it denotes the absence of a return type.)
76 * <p>
77 * All instances of {@code MethodType} are immutable.
78 * Two instances are completely interchangeable if they compare equal.
79 * Equality depends on pairwise correspondence of the return and parameter types and on nothing else.
80 * <p>
81 * This type can be created only by factory methods.
82 * All factory methods may cache values, though caching is not guaranteed.
83 * Some factory methods are static, while others are virtual methods which
84 * modify precursor method types, e.g., by changing a selected parameter.
85 * <p>
86 * Factory methods which operate on groups of parameter types
87 * are systematically presented in two versions, so that both Java arrays and
88 * Java lists can be used to work with groups of parameter types.
89 * The query methods {@code parameterArray} and {@code parameterList}
90 * also provide a choice between arrays and lists.
91 * <p>
92 * {@code MethodType} objects are sometimes derived from bytecode instructions
93 * such as {@code invokedynamic}, specifically from the type descriptor strings associated
94 * with the instructions in a class file's constant pool.
95 * <p>
96 * Like classes and strings, method types can also be represented directly
97 * in a class file's constant pool as constants.
98 * A method type may be loaded by an {@code ldc} instruction which refers
99 * to a suitable {@code CONSTANT_MethodType} constant pool entry.
100 * The entry refers to a {@code CONSTANT_Utf8} spelling for the descriptor string.
101 * (For full details on method type constants, see sections {@jvms
102 * 4.4.8} and {@jvms 5.4.3.5} of the Java Virtual Machine
103 * Specification.)
104 * <p>
105 * When the JVM materializes a {@code MethodType} from a descriptor string,
106 * all classes named in the descriptor must be accessible, and will be loaded.
107 * (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.)
108 * This loading may occur at any time before the {@code MethodType} object is first derived.
109 * <p>
110 * <b><a id="descriptor">Nominal Descriptors</a></b>
111 * <p>
112 * A {@code MethodType} can be described in {@linkplain MethodTypeDesc nominal form}
113 * if and only if all of the parameter types and return type can be described
114 * with a {@link Class#describeConstable() nominal descriptor} represented by
115 * {@link ClassDesc}. If a method type can be described nominally, then:
116 * <ul>
117 * <li>The method type has a {@link MethodTypeDesc nominal descriptor}
118 * returned by {@link #describeConstable() MethodType::describeConstable}.</li>
119 * <li>The descriptor string returned by
120 * {@link #descriptorString() MethodType::descriptorString} or
121 * {@link #toMethodDescriptorString() MethodType::toMethodDescriptorString}
122 * for the method type is a method descriptor (JVMS {@jvms 4.3.3}).</li>
123 * </ul>
124 * <p>
125 * If any of the parameter types or return type cannot be described
126 * nominally, i.e. {@link Class#describeConstable() Class::describeConstable}
127 * returns an empty optional for that type,
128 * then the method type cannot be described nominally:
129 * <ul>
130 * <li>The method type has no {@link MethodTypeDesc nominal descriptor} and
131 * {@link #describeConstable() MethodType::describeConstable} returns
132 * an empty optional.</li>
133 * <li>The descriptor string returned by
134 * {@link #descriptorString() MethodType::descriptorString} or
135 * {@link #toMethodDescriptorString() MethodType::toMethodDescriptorString}
136 * for the method type is not a type descriptor.</li>
137 * </ul>
138 *
139 * @author John Rose, JSR 292 EG
140 * @since 1.7
141 */
142 public final
143 class MethodType
144 implements Constable,
145 TypeDescriptor.OfMethod<Class<?>, MethodType>,
146 java.io.Serializable {
147 @java.io.Serial
148 private static final long serialVersionUID = 292L; // {rtype, {ptype...}}
149
150 // The rtype and ptypes fields define the structural identity of the method type:
151 private final @Stable Class<?> rtype;
152 private final @Stable Class<?>[] ptypes;
153
154 // The remaining fields are caches of various sorts:
155 private @Stable MethodTypeForm form; // erased form, plus cached data about primitives
156 private @Stable Object wrapAlt; // alternative wrapped/unwrapped version and
157 // private communication for readObject and readResolve
158 private @Stable Invokers invokers; // cache of handy higher-order adapters
159 private @Stable String methodDescriptor; // cache for toMethodDescriptorString
160
161 private final boolean checkArchivable = CDS.isDumpingArchive();
162 /**
163 * Constructor that performs no copying or validation.
164 * Should only be called from the factory method makeImpl
165 */
166 private MethodType(Class<?> rtype, Class<?>[] ptypes) {
167 if (checkArchivable) {
168 MethodHandleNatives.checkArchivable(rtype);
169 for (var p : ptypes) {
170 MethodHandleNatives.checkArchivable(p);
171 }
172 }
173
174 this.rtype = rtype;
175 this.ptypes = ptypes;
176 }
177
178 /*trusted*/ MethodTypeForm form() { return form; }
179 /*trusted*/ Class<?> rtype() { return rtype; }
180 /*trusted*/ Class<?>[] ptypes() { return ptypes; }
181
182 void setForm(MethodTypeForm f) { form = f; }
183
184 /** This number, mandated by the JVM spec as 255,
185 * is the maximum number of <em>slots</em>
186 * that any Java method can receive in its argument list.
187 * It limits both JVM signatures and method type objects.
188 * The longest possible invocation will look like
189 * {@code staticMethod(arg1, arg2, ..., arg255)} or
190 * {@code x.virtualMethod(arg1, arg2, ..., arg254)}.
191 */
192 /*non-public*/
193 static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec.
194
195 /** This number is the maximum arity of a method handle, 254.
196 * It is derived from the absolute JVM-imposed arity by subtracting one,
197 * which is the slot occupied by the method handle itself at the
198 * beginning of the argument list used to invoke the method handle.
199 * The longest possible invocation will look like
200 * {@code mh.invoke(arg1, arg2, ..., arg254)}.
201 */
202 // Issue: Should we allow MH.invokeWithArguments to go to the full 255?
203 /*non-public*/
204 static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver
205
206 /** This number is the maximum arity of a method handle invoker, 253.
207 * It is derived from the absolute JVM-imposed arity by subtracting two,
208 * which are the slots occupied by invoke method handle, and the
209 * target method handle, which are both at the beginning of the argument
210 * list used to invoke the target method handle.
211 * The longest possible invocation will look like
212 * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}.
213 */
214 /*non-public*/
215 static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker
216
217 /** Return number of extra slots (count of long/double args). */
218 private static int checkPtypes(Class<?>[] ptypes) {
219 int slots = 0;
220 for (Class<?> ptype : ptypes) {
221 Objects.requireNonNull(ptype);
222 if (ptype == void.class)
223 throw newIllegalArgumentException("parameter type cannot be void");
224 if (ptype == double.class || ptype == long.class) {
225 slots++;
226 }
227 }
228 checkSlotCount(ptypes.length + slots);
229 return slots;
230 }
231
232 static {
233 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work:
234 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0);
235 }
236 static void checkSlotCount(int count) {
237 if ((count & MAX_JVM_ARITY) != count)
238 throw newIllegalArgumentException("bad parameter count "+count);
239 }
240 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) {
241 if (num instanceof Integer) num = "bad index: "+num;
242 return new IndexOutOfBoundsException(num.toString());
243 }
244
245 static final ReferencedKeySet<MethodType> internTable =
246 ReferencedKeySet.create(false, true, new Supplier<>() {
247 @Override
248 public Map<ReferenceKey<MethodType>, ReferenceKey<MethodType>> get() {
249 return new ConcurrentHashMap<>(512);
250 }
251 });
252
253 static final Class<?>[] NO_PTYPES = {};
254
255 private static Object[] archivedObjects;
256
257 private static @Stable HashMap<MethodType,MethodType> archivedMethodTypes;
258
259 private static @Stable MethodType[] objectOnlyTypes;
260
261 @SuppressWarnings("unchecked")
262 static void doit() {
263 CDS.initializeFromArchive(MethodType.class);
264 if (archivedObjects != null) {
265 archivedMethodTypes = (HashMap<MethodType,MethodType>)archivedObjects[0];
266 objectOnlyTypes = (MethodType[])archivedObjects[1];
267 } else {
268 objectOnlyTypes = new MethodType[20];
269 }
270 }
271 static {
272 doit();
273 }
274
275 /**
276 * Finds or creates an instance of the given method type.
277 * @param rtype the return type
278 * @param ptypes the parameter types
279 * @return a method type with the given components
280 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
281 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
282 */
283 public static MethodType methodType(Class<?> rtype, Class<?>[] ptypes) {
284 return methodType(rtype, ptypes, false);
285 }
286
287 /**
288 * Finds or creates a method type with the given components.
289 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
290 * @param rtype the return type
291 * @param ptypes the parameter types
292 * @return a method type with the given components
293 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
294 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
295 */
296 public static MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) {
297 boolean notrust = false; // random List impl. could return evil ptypes array
298 return methodType(rtype, listToArray(ptypes), notrust);
299 }
300
301 private static Class<?>[] listToArray(List<Class<?>> ptypes) {
302 // sanity check the size before the toArray call, since size might be huge
303 checkSlotCount(ptypes.size());
304 return ptypes.toArray(NO_PTYPES);
305 }
306
307 /**
308 * Finds or creates a method type with the given components.
309 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
310 * The leading parameter type is prepended to the remaining array.
311 * @param rtype the return type
312 * @param ptype0 the first parameter type
313 * @param ptypes the remaining parameter types
314 * @return a method type with the given components
315 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null
316 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class}
317 */
318 public static MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) {
319 int len = ptypes.length;
320 if (rtype == Object.class && ptype0 == Object.class) {
321 if (len == 0) {
322 return genericMethodType(1, false);
323 }
324 if (isAllObject(ptypes, len - 1)) {
325 Class<?> lastParam = ptypes[len - 1];
326 if (lastParam == Object.class) {
327 return genericMethodType(len + 1, false);
328 } else if (lastParam == Object[].class) {
329 return genericMethodType(len, true);
330 }
331 }
332 }
333 Class<?>[] ptypes1 = new Class<?>[1 + len];
334 ptypes1[0] = ptype0;
335 System.arraycopy(ptypes, 0, ptypes1, 1, len);
336 return makeImpl(rtype, ptypes1, true);
337 }
338
339 /**
340 * Finds or creates a method type with the given components.
341 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
342 * The resulting method has no parameter types.
343 * @param rtype the return type
344 * @return a method type with the given return value
345 * @throws NullPointerException if {@code rtype} is null
346 */
347 public static MethodType methodType(Class<?> rtype) {
348 if (rtype == Object.class) {
349 return genericMethodType(0, false);
350 }
351 return makeImpl(rtype, NO_PTYPES, 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 single given parameter type.
358 * @param rtype the return type
359 * @param ptype0 the parameter type
360 * @return a method type with the given return value and parameter type
361 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null
362 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class}
363 */
364 public static MethodType methodType(Class<?> rtype, Class<?> ptype0) {
365 if (rtype == Object.class) {
366 if (ptype0 == Object.class) {
367 return genericMethodType(1, false);
368 } else if (ptype0 == Object[].class) {
369 return genericMethodType(0, true);
370 }
371 }
372 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true);
373 }
374
375 /**
376 * Finds or creates a method type with the given components.
377 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
378 * The resulting method has the same parameter types as {@code ptypes},
379 * and the specified return type.
380 * @param rtype the return type
381 * @param ptypes the method type which supplies the parameter types
382 * @return a method type with the given components
383 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null
384 */
385 public static MethodType methodType(Class<?> rtype, MethodType ptypes) {
386 return methodType(rtype, ptypes.ptypes, true);
387 }
388
389 private static boolean isAllObject(Class<?>[] ptypes, int to) {
390 for (int i = 0; i < to; i++) {
391 if (ptypes[i] != Object.class) {
392 return false;
393 }
394 }
395 return true;
396 }
397
398 /*trusted*/
399 static MethodType methodType(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
400 if (rtype == Object.class) {
401 int last = ptypes.length - 1;
402 if (last < 0) {
403 return genericMethodType(0, false);
404 }
405 if (isAllObject(ptypes, last)) {
406 Class<?> lastParam = ptypes[last];
407 if (lastParam == Object.class) {
408 return genericMethodType(last + 1, false);
409 } else if (lastParam == Object[].class) {
410 return genericMethodType(last, true);
411 }
412 }
413 }
414 return makeImpl(rtype, ptypes, trusted);
415 }
416
417 /**
418 * Sole factory method to find or create an interned method type. Will perform
419 * input validation on behalf of factory methods
420 *
421 * @param rtype desired return type
422 * @param ptypes desired parameter types
423 * @param trusted whether the ptypes can be used without cloning
424 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
425 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
426 * @return the unique method type of the desired structure
427 */
428 private static MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
429 if (ptypes.length == 0) {
430 ptypes = NO_PTYPES; trusted = true;
431 }
432 MethodType primordialMT = new MethodType(rtype, ptypes);
433 if (archivedMethodTypes != null) {
434 MethodType mt = archivedMethodTypes.get(primordialMT);
435 if (mt != null) {
436 return mt;
437 }
438 }
439
440 MethodType mt = internTable.get(primordialMT);
441 if (mt != null)
442 return mt;
443
444 // promote the object to the Real Thing, and reprobe
445 Objects.requireNonNull(rtype);
446 if (trusted) {
447 MethodType.checkPtypes(ptypes);
448 mt = primordialMT;
449 } else {
450 // Make defensive copy then validate
451 ptypes = Arrays.copyOf(ptypes, ptypes.length);
452 MethodType.checkPtypes(ptypes);
453 mt = new MethodType(rtype, ptypes);
454 }
455 mt.form = MethodTypeForm.findForm(mt);
456 return internTable.intern(mt);
457 }
458
459 /**
460 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array.
461 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
462 * All parameters and the return type will be {@code Object},
463 * except the final array parameter if any, which will be {@code Object[]}.
464 * @param objectArgCount number of parameters (excluding the final array parameter if any)
465 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]}
466 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments
467 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true)
468 * @see #genericMethodType(int)
469 */
470 public static MethodType genericMethodType(int objectArgCount, boolean finalArray) {
471 MethodType mt;
472 checkSlotCount(objectArgCount);
473 int ivarargs = (!finalArray ? 0 : 1);
474 int ootIndex = objectArgCount*2 + ivarargs;
475 if (ootIndex < objectOnlyTypes.length) {
476 mt = objectOnlyTypes[ootIndex];
477 if (mt != null) return mt;
478 }
479 Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs];
480 Arrays.fill(ptypes, Object.class);
481 if (ivarargs != 0) ptypes[objectArgCount] = Object[].class;
482 mt = makeImpl(Object.class, ptypes, true);
483 if (ootIndex < objectOnlyTypes.length) {
484 objectOnlyTypes[ootIndex] = mt; // cache it here also!
485 }
486 return mt;
487 }
488
489 /**
490 * Finds or creates a method type whose components are all {@code Object}.
491 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
492 * All parameters and the return type will be Object.
493 * @param objectArgCount number of parameters
494 * @return a generally applicable method type, for all calls of the given argument count
495 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255
496 * @see #genericMethodType(int, boolean)
497 */
498 public static MethodType genericMethodType(int objectArgCount) {
499 return genericMethodType(objectArgCount, false);
500 }
501
502 /**
503 * Finds or creates a method type with a single different parameter type.
504 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
505 * @param num the index (zero-based) of the parameter type to change
506 * @param nptype a new parameter type to replace the old one with
507 * @return the same type, except with the selected parameter changed
508 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
509 * @throws IllegalArgumentException if {@code nptype} is {@code void.class}
510 * @throws NullPointerException if {@code nptype} is null
511 */
512 public MethodType changeParameterType(int num, Class<?> nptype) {
513 if (parameterType(num) == nptype) return this;
514 Class<?>[] nptypes = ptypes.clone();
515 nptypes[num] = nptype;
516 return makeImpl(rtype, nptypes, true);
517 }
518
519 /**
520 * Finds or creates a method type with additional parameter types.
521 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
522 * @param num the position (zero-based) of the inserted parameter type(s)
523 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
524 * @return the same type, except with the selected parameter(s) inserted
525 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
526 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
527 * or if the resulting method type would have more than 255 parameter slots
528 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
529 */
530 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) {
531 int len = ptypes.length;
532 if (num < 0 || num > len)
533 throw newIndexOutOfBoundsException(num);
534 int ins = checkPtypes(ptypesToInsert);
535 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins);
536 int ilen = ptypesToInsert.length;
537 if (ilen == 0) return this;
538 Class<?>[] nptypes = new Class<?>[len + ilen];
539 if (num > 0) {
540 System.arraycopy(ptypes, 0, nptypes, 0, num);
541 }
542 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen);
543 if (num < len) {
544 System.arraycopy(ptypes, num, nptypes, num+ilen, len-num);
545 }
546 return makeImpl(rtype, nptypes, true);
547 }
548
549 /**
550 * Finds or creates a method type with additional parameter types.
551 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
552 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
553 * @return the same type, except with the selected parameter(s) appended
554 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
555 * or if the resulting method type would have more than 255 parameter slots
556 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
557 */
558 public MethodType appendParameterTypes(Class<?>... ptypesToInsert) {
559 return insertParameterTypes(parameterCount(), ptypesToInsert);
560 }
561
562 /**
563 * Finds or creates a method type with additional parameter types.
564 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
565 * @param num the position (zero-based) of the inserted parameter type(s)
566 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
567 * @return the same type, except with the selected parameter(s) inserted
568 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
569 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
570 * or if the resulting method type would have more than 255 parameter slots
571 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
572 */
573 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) {
574 return insertParameterTypes(num, listToArray(ptypesToInsert));
575 }
576
577 /**
578 * Finds or creates a method type with additional parameter types.
579 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
580 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
581 * @return the same type, except with the selected parameter(s) appended
582 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
583 * or if the resulting method type would have more than 255 parameter slots
584 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
585 */
586 public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) {
587 return insertParameterTypes(parameterCount(), ptypesToInsert);
588 }
589
590 /**
591 * Finds or creates a method type with modified parameter types.
592 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
593 * @param start the position (zero-based) of the first replaced parameter type(s)
594 * @param end the position (zero-based) after the last replaced parameter type(s)
595 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
596 * @return the same type, except with the selected parameter(s) replaced
597 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
598 * or if {@code end} is negative or greater than {@code parameterCount()}
599 * or if {@code start} is greater than {@code end}
600 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
601 * or if the resulting method type would have more than 255 parameter slots
602 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
603 */
604 /*non-public*/
605 MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) {
606 if (start == end)
607 return insertParameterTypes(start, ptypesToInsert);
608 int len = ptypes.length;
609 if (!(0 <= start && start <= end && end <= len))
610 throw newIndexOutOfBoundsException("start="+start+" end="+end);
611 int ilen = ptypesToInsert.length;
612 if (ilen == 0)
613 return dropParameterTypes(start, end);
614 return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert);
615 }
616
617 /** Replace the last arrayLength parameter types with the component type of arrayType.
618 * @param arrayType any array type
619 * @param pos position at which to spread
620 * @param arrayLength the number of parameter types to change
621 * @return the resulting type
622 */
623 /*non-public*/
624 MethodType asSpreaderType(Class<?> arrayType, int pos, int arrayLength) {
625 assert(parameterCount() >= arrayLength);
626 int spreadPos = pos;
627 if (arrayLength == 0) return this; // nothing to change
628 if (arrayType == Object[].class) {
629 if (isGeneric()) return this; // nothing to change
630 if (spreadPos == 0) {
631 // no leading arguments to preserve; go generic
632 MethodType res = genericMethodType(arrayLength);
633 if (rtype != Object.class) {
634 res = res.changeReturnType(rtype);
635 }
636 return res;
637 }
638 }
639 Class<?> elemType = arrayType.getComponentType();
640 assert(elemType != null);
641 for (int i = spreadPos; i < spreadPos + arrayLength; i++) {
642 if (ptypes[i] != elemType) {
643 Class<?>[] fixedPtypes = ptypes.clone();
644 Arrays.fill(fixedPtypes, i, spreadPos + arrayLength, elemType);
645 return methodType(rtype, fixedPtypes);
646 }
647 }
648 return this; // arguments check out; no change
649 }
650
651 /** Return the leading parameter type, which must exist and be a reference.
652 * @return the leading parameter type, after error checks
653 */
654 /*non-public*/
655 Class<?> leadingReferenceParameter() {
656 Class<?> ptype;
657 if (ptypes.length == 0 ||
658 (ptype = ptypes[0]).isPrimitive())
659 throw newIllegalArgumentException("no leading reference parameter");
660 return ptype;
661 }
662
663 /** Delete the last parameter type and replace it with arrayLength copies of the component type of arrayType.
664 * @param arrayType any array type
665 * @param pos position at which to insert parameters
666 * @param arrayLength the number of parameter types to insert
667 * @return the resulting type
668 */
669 /*non-public*/
670 MethodType asCollectorType(Class<?> arrayType, int pos, int arrayLength) {
671 assert(parameterCount() >= 1);
672 assert(pos < ptypes.length);
673 assert(ptypes[pos].isAssignableFrom(arrayType));
674 MethodType res;
675 if (arrayType == Object[].class) {
676 res = genericMethodType(arrayLength);
677 if (rtype != Object.class) {
678 res = res.changeReturnType(rtype);
679 }
680 } else {
681 Class<?> elemType = arrayType.getComponentType();
682 assert(elemType != null);
683 res = methodType(rtype, Collections.nCopies(arrayLength, elemType));
684 }
685 if (ptypes.length == 1) {
686 return res;
687 } else {
688 // insert after (if need be), then before
689 if (pos < ptypes.length - 1) {
690 res = res.insertParameterTypes(arrayLength, Arrays.copyOfRange(ptypes, pos + 1, ptypes.length));
691 }
692 return res.insertParameterTypes(0, Arrays.copyOf(ptypes, pos));
693 }
694 }
695
696 /**
697 * Finds or creates a method type with some parameter types omitted.
698 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
699 * @param start the index (zero-based) of the first parameter type to remove
700 * @param end the index (greater than {@code start}) of the first parameter type after not to remove
701 * @return the same type, except with the selected parameter(s) removed
702 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
703 * or if {@code end} is negative or greater than {@code parameterCount()}
704 * or if {@code start} is greater than {@code end}
705 */
706 public MethodType dropParameterTypes(int start, int end) {
707 int len = ptypes.length;
708 if (!(0 <= start && start <= end && end <= len))
709 throw newIndexOutOfBoundsException("start="+start+" end="+end);
710 if (start == end) return this;
711 Class<?>[] nptypes;
712 if (start == 0) {
713 if (end == len) {
714 // drop all parameters
715 nptypes = NO_PTYPES;
716 } else {
717 // drop initial parameter(s)
718 nptypes = Arrays.copyOfRange(ptypes, end, len);
719 }
720 } else {
721 if (end == len) {
722 // drop trailing parameter(s)
723 nptypes = Arrays.copyOfRange(ptypes, 0, start);
724 } else {
725 int tail = len - end;
726 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail);
727 System.arraycopy(ptypes, end, nptypes, start, tail);
728 }
729 }
730 return methodType(rtype, nptypes, true);
731 }
732
733 /**
734 * Finds or creates a method type with a different return type.
735 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
736 * @param nrtype a return parameter type to replace the old one with
737 * @return the same type, except with the return type change
738 * @throws NullPointerException if {@code nrtype} is null
739 */
740 public MethodType changeReturnType(Class<?> nrtype) {
741 if (returnType() == nrtype) return this;
742 return methodType(nrtype, ptypes, true);
743 }
744
745 /**
746 * Reports if this type contains a primitive argument or return value.
747 * The return type {@code void} counts as a primitive.
748 * @return true if any of the types are primitives
749 */
750 public boolean hasPrimitives() {
751 return form.hasPrimitives();
752 }
753
754 /**
755 * Reports if this type contains a wrapper argument or return value.
756 * Wrappers are types which box primitive values, such as {@link Integer}.
757 * The reference type {@code java.lang.Void} counts as a wrapper,
758 * if it occurs as a return type.
759 * @return true if any of the types are wrappers
760 */
761 public boolean hasWrappers() {
762 return unwrap() != this;
763 }
764
765 /**
766 * Erases all reference types to {@code Object}.
767 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
768 * All primitive types (including {@code void}) will remain unchanged.
769 * @return a version of the original type with all reference types replaced
770 */
771 public MethodType erase() {
772 return form.erasedType();
773 }
774
775 /**
776 * Erases all reference types to {@code Object}, and all subword types to {@code int}.
777 * This is the reduced type polymorphism used by private methods
778 * such as {@link MethodHandle#invokeBasic invokeBasic}.
779 * @return a version of the original type with all reference and subword types replaced
780 */
781 /*non-public*/
782 MethodType basicType() {
783 return form.basicType();
784 }
785
786 private static final @Stable Class<?>[] METHOD_HANDLE_ARRAY
787 = new Class<?>[] { MethodHandle.class };
788
789 /**
790 * @return a version of the original type with MethodHandle prepended as the first argument
791 */
792 /*non-public*/
793 MethodType invokerType() {
794 return insertParameterTypes(0, METHOD_HANDLE_ARRAY);
795 }
796
797 /**
798 * Converts all types, both reference and primitive, to {@code Object}.
799 * Convenience method for {@link #genericMethodType(int) genericMethodType}.
800 * The expression {@code type.wrap().erase()} produces the same value
801 * as {@code type.generic()}.
802 * @return a version of the original type with all types replaced
803 */
804 public MethodType generic() {
805 return genericMethodType(parameterCount());
806 }
807
808 /*non-public*/
809 boolean isGeneric() {
810 return this == erase() && !hasPrimitives();
811 }
812
813 /**
814 * Converts all primitive types to their corresponding wrapper types.
815 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
816 * All reference types (including wrapper types) will remain unchanged.
817 * A {@code void} return type is changed to the type {@code java.lang.Void}.
818 * The expression {@code type.wrap().erase()} produces the same value
819 * as {@code type.generic()}.
820 * @return a version of the original type with all primitive types replaced
821 */
822 public MethodType wrap() {
823 return hasPrimitives() ? wrapWithPrims(this) : this;
824 }
825
826 /**
827 * Converts all wrapper types to their corresponding primitive types.
828 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
829 * All primitive types (including {@code void}) will remain unchanged.
830 * A return type of {@code java.lang.Void} is changed to {@code void}.
831 * @return a version of the original type with all wrapper types replaced
832 */
833 public MethodType unwrap() {
834 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this);
835 return unwrapWithNoPrims(noprims);
836 }
837
838 private static MethodType wrapWithPrims(MethodType pt) {
839 assert(pt.hasPrimitives());
840 MethodType wt = (MethodType)pt.wrapAlt;
841 if (wt == null) {
842 // fill in lazily
843 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP);
844 assert(wt != null);
845 pt.wrapAlt = wt;
846 }
847 return wt;
848 }
849
850 private static MethodType unwrapWithNoPrims(MethodType wt) {
851 assert(!wt.hasPrimitives());
852 MethodType uwt = (MethodType)wt.wrapAlt;
853 if (uwt == null) {
854 // fill in lazily
855 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP);
856 if (uwt == null)
857 uwt = wt; // type has no wrappers or prims at all
858 wt.wrapAlt = uwt;
859 }
860 return uwt;
861 }
862
863 /**
864 * Returns the parameter type at the specified index, within this method type.
865 * @param num the index (zero-based) of the desired parameter type
866 * @return the selected parameter type
867 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
868 */
869 public Class<?> parameterType(int num) {
870 return ptypes[num];
871 }
872 /**
873 * Returns the number of parameter types in this method type.
874 * @return the number of parameter types
875 */
876 public int parameterCount() {
877 return ptypes.length;
878 }
879 /**
880 * Returns the return type of this method type.
881 * @return the return type
882 */
883 public Class<?> returnType() {
884 return rtype;
885 }
886
887 /**
888 * Presents the parameter types as a list (a convenience method).
889 * The list will be immutable.
890 * @return the parameter types (as an immutable list)
891 */
892 public List<Class<?>> parameterList() {
893 return List.of(ptypes);
894 }
895
896 /**
897 * Returns the last parameter type of this method type.
898 * If this type has no parameters, the sentinel value
899 * {@code void.class} is returned instead.
900 * @apiNote
901 * <p>
902 * The sentinel value is chosen so that reflective queries can be
903 * made directly against the result value.
904 * The sentinel value cannot be confused with a real parameter,
905 * since {@code void} is never acceptable as a parameter type.
906 * For variable arity invocation modes, the expression
907 * {@link Class#getComponentType lastParameterType().getComponentType()}
908 * is useful to query the type of the "varargs" parameter.
909 * @return the last parameter type if any, else {@code void.class}
910 * @since 10
911 */
912 public Class<?> lastParameterType() {
913 int len = ptypes.length;
914 return len == 0 ? void.class : ptypes[len-1];
915 }
916
917 /**
918 * Presents the parameter types as an array (a convenience method).
919 * Changes to the array will not result in changes to the type.
920 * @return the parameter types (as a fresh copy if necessary)
921 */
922 public Class<?>[] parameterArray() {
923 return ptypes.clone();
924 }
925
926 /**
927 * Compares the specified object with this type for equality.
928 * That is, it returns {@code true} if and only if the specified object
929 * is also a method type with exactly the same parameters and return type.
930 * @param x object to compare
931 * @see Object#equals(Object)
932 */
933 @Override
934 public boolean equals(Object x) {
935 if (this == x) {
936 return true;
937 }
938 if (x instanceof MethodType mt) {
939 return equals(mt);
940 }
941 return false;
942 }
943
944 private boolean equals(MethodType that) {
945 return this.rtype == that.rtype
946 && Arrays.equals(this.ptypes, that.ptypes);
947 }
948
949 /**
950 * Returns the hash code value for this method type.
951 * It is defined to be the same as the hashcode of a List
952 * whose elements are the return type followed by the
953 * parameter types.
954 * @return the hash code value for this method type
955 * @see Object#hashCode()
956 * @see #equals(Object)
957 * @see List#hashCode()
958 */
959 @Override
960 public int hashCode() {
961 int hashCode = 31 + rtype.hashCode();
962 for (Class<?> ptype : ptypes)
963 hashCode = 31 * hashCode + ptype.hashCode();
964 return hashCode;
965 }
966
967 /**
968 * Returns a string representation of the method type,
969 * of the form {@code "(PT0,PT1...)RT"}.
970 * The string representation of a method type is a
971 * parenthesis enclosed, comma separated list of type names,
972 * followed immediately by the return type.
973 * <p>
974 * Each type is represented by its
975 * {@link java.lang.Class#getSimpleName simple name}.
976 */
977 @Override
978 public String toString() {
979 StringJoiner sj = new StringJoiner(",", "(",
980 ")" + rtype.getSimpleName());
981 for (int i = 0; i < ptypes.length; i++) {
982 sj.add(ptypes[i].getSimpleName());
983 }
984 return sj.toString();
985 }
986
987 /** True if my parameter list is effectively identical to the given full list,
988 * after skipping the given number of my own initial parameters.
989 * In other words, after disregarding {@code skipPos} parameters,
990 * my remaining parameter list is no longer than the {@code fullList}, and
991 * is equal to the same-length initial sublist of {@code fullList}.
992 */
993 /*non-public*/
994 boolean effectivelyIdenticalParameters(int skipPos, List<Class<?>> fullList) {
995 int myLen = ptypes.length, fullLen = fullList.size();
996 if (skipPos > myLen || myLen - skipPos > fullLen)
997 return false;
998 List<Class<?>> myList = Arrays.asList(ptypes);
999 if (skipPos != 0) {
1000 myList = myList.subList(skipPos, myLen);
1001 myLen -= skipPos;
1002 }
1003 if (fullLen == myLen)
1004 return myList.equals(fullList);
1005 else
1006 return myList.equals(fullList.subList(0, myLen));
1007 }
1008
1009 /** True if the old return type can always be viewed (w/o casting) under new return type,
1010 * and the new parameters can be viewed (w/o casting) under the old parameter types.
1011 */
1012 /*non-public*/
1013 boolean isViewableAs(MethodType newType, boolean keepInterfaces) {
1014 if (!VerifyType.isNullConversion(returnType(), newType.returnType(), keepInterfaces))
1015 return false;
1016 if (form == newType.form && form.erasedType == this)
1017 return true; // my reference parameters are all Object
1018 if (ptypes == newType.ptypes)
1019 return true;
1020 int argc = parameterCount();
1021 if (argc != newType.parameterCount())
1022 return false;
1023 for (int i = 0; i < argc; i++) {
1024 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i), keepInterfaces))
1025 return false;
1026 }
1027 return true;
1028 }
1029 /*non-public*/
1030 boolean isConvertibleTo(MethodType newType) {
1031 MethodTypeForm oldForm = this.form();
1032 MethodTypeForm newForm = newType.form();
1033 if (oldForm == newForm)
1034 // same parameter count, same primitive/object mix
1035 return true;
1036 if (!canConvert(returnType(), newType.returnType()))
1037 return false;
1038 Class<?>[] srcTypes = newType.ptypes;
1039 Class<?>[] dstTypes = ptypes;
1040 if (srcTypes == dstTypes)
1041 return true;
1042 int argc;
1043 if ((argc = srcTypes.length) != dstTypes.length)
1044 return false;
1045 if (argc <= 1) {
1046 if (argc == 1 && !canConvert(srcTypes[0], dstTypes[0]))
1047 return false;
1048 return true;
1049 }
1050 if ((!oldForm.hasPrimitives() && oldForm.erasedType == this) ||
1051 (!newForm.hasPrimitives() && newForm.erasedType == newType)) {
1052 // Somewhat complicated test to avoid a loop of 2 or more trips.
1053 // If either type has only Object parameters, we know we can convert.
1054 assert(canConvertParameters(srcTypes, dstTypes));
1055 return true;
1056 }
1057 return canConvertParameters(srcTypes, dstTypes);
1058 }
1059
1060 /** Returns true if MHs.explicitCastArguments produces the same result as MH.asType.
1061 * If the type conversion is impossible for either, the result should be false.
1062 */
1063 /*non-public*/
1064 boolean explicitCastEquivalentToAsType(MethodType newType) {
1065 if (this == newType) return true;
1066 if (!explicitCastEquivalentToAsType(rtype, newType.rtype)) {
1067 return false;
1068 }
1069 Class<?>[] srcTypes = newType.ptypes;
1070 Class<?>[] dstTypes = ptypes;
1071 if (dstTypes == srcTypes) {
1072 return true;
1073 }
1074 assert(dstTypes.length == srcTypes.length);
1075 for (int i = 0; i < dstTypes.length; i++) {
1076 if (!explicitCastEquivalentToAsType(srcTypes[i], dstTypes[i])) {
1077 return false;
1078 }
1079 }
1080 return true;
1081 }
1082
1083 /** Reports true if the src can be converted to the dst, by both asType and MHs.eCE,
1084 * and with the same effect.
1085 * MHs.eCA has the following "upgrades" to MH.asType:
1086 * 1. interfaces are unchecked (that is, treated as if aliased to Object)
1087 * Therefore, {@code Object->CharSequence} is possible in both cases but has different semantics
1088 * 2. the full matrix of primitive-to-primitive conversions is supported
1089 * Narrowing like {@code long->byte} and basic-typing like {@code boolean->int}
1090 * are not supported by asType, but anything supported by asType is equivalent
1091 * with MHs.eCE.
1092 * 3a. unboxing conversions can be followed by the full matrix of primitive conversions
1093 * 3b. unboxing of null is permitted (creates a zero primitive value)
1094 * Other than interfaces, reference-to-reference conversions are the same.
1095 * Boxing primitives to references is the same for both operators.
1096 */
1097 private static boolean explicitCastEquivalentToAsType(Class<?> src, Class<?> dst) {
1098 if (src == dst || dst == Object.class || dst == void.class) return true;
1099 if (src.isPrimitive()) {
1100 // Could be a prim/prim conversion, where casting is a strict superset.
1101 // Or a boxing conversion, which is always to an exact wrapper class.
1102 return canConvert(src, dst);
1103 } else if (dst.isPrimitive()) {
1104 // Unboxing behavior is different between MHs.eCA & MH.asType (see 3b).
1105 return false;
1106 } else {
1107 // R->R always works, but we have to avoid a check-cast to an interface.
1108 return !dst.isInterface() || dst.isAssignableFrom(src);
1109 }
1110 }
1111
1112 private boolean canConvertParameters(Class<?>[] srcTypes, Class<?>[] dstTypes) {
1113 for (int i = 0; i < srcTypes.length; i++) {
1114 if (!canConvert(srcTypes[i], dstTypes[i])) {
1115 return false;
1116 }
1117 }
1118 return true;
1119 }
1120
1121 /*non-public*/
1122 static boolean canConvert(Class<?> src, Class<?> dst) {
1123 // short-circuit a few cases:
1124 if (src == dst || src == Object.class || dst == Object.class) return true;
1125 // the remainder of this logic is documented in MethodHandle.asType
1126 if (src.isPrimitive()) {
1127 // can force void to an explicit null, a la reflect.Method.invoke
1128 // can also force void to a primitive zero, by analogy
1129 if (src == void.class) return true; //or !dst.isPrimitive()?
1130 Wrapper sw = Wrapper.forPrimitiveType(src);
1131 if (dst.isPrimitive()) {
1132 // P->P must widen
1133 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw);
1134 } else {
1135 // P->R must box and widen
1136 return dst.isAssignableFrom(sw.wrapperType());
1137 }
1138 } else if (dst.isPrimitive()) {
1139 // any value can be dropped
1140 if (dst == void.class) return true;
1141 Wrapper dw = Wrapper.forPrimitiveType(dst);
1142 // R->P must be able to unbox (from a dynamically chosen type) and widen
1143 // For example:
1144 // Byte/Number/Comparable/Object -> dw:Byte -> byte.
1145 // Character/Comparable/Object -> dw:Character -> char
1146 // Boolean/Comparable/Object -> dw:Boolean -> boolean
1147 // This means that dw must be cast-compatible with src.
1148 if (src.isAssignableFrom(dw.wrapperType())) {
1149 return true;
1150 }
1151 // The above does not work if the source reference is strongly typed
1152 // to a wrapper whose primitive must be widened. For example:
1153 // Byte -> unbox:byte -> short/int/long/float/double
1154 // Character -> unbox:char -> int/long/float/double
1155 if (Wrapper.isWrapperType(src) &&
1156 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) {
1157 // can unbox from src and then widen to dst
1158 return true;
1159 }
1160 // We have already covered cases which arise due to runtime unboxing
1161 // of a reference type which covers several wrapper types:
1162 // Object -> cast:Integer -> unbox:int -> long/float/double
1163 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double
1164 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a
1165 // subclass of Number which wraps a value that can convert to char.
1166 // Since there is none, we don't need an extra check here to cover char or boolean.
1167 return false;
1168 } else {
1169 // R->R always works, since null is always valid dynamically
1170 return true;
1171 }
1172 }
1173
1174 /// Queries which have to do with the bytecode architecture
1175
1176 /** Reports the number of JVM stack slots required to invoke a method
1177 * of this type. Note that (for historical reasons) the JVM requires
1178 * a second stack slot to pass long and double arguments.
1179 * So this method returns {@link #parameterCount() parameterCount} plus the
1180 * number of long and double parameters (if any).
1181 * <p>
1182 * This method is included for the benefit of applications that must
1183 * generate bytecodes that process method handles and invokedynamic.
1184 * @return the number of JVM stack slots for this type's parameters
1185 */
1186 /*non-public*/
1187 int parameterSlotCount() {
1188 return form.parameterSlotCount();
1189 }
1190
1191 /*non-public*/
1192 Invokers invokers() {
1193 Invokers inv = invokers;
1194 if (inv != null) return inv;
1195 invokers = inv = new Invokers(this);
1196 return inv;
1197 }
1198
1199 /**
1200 * Finds or creates an instance of a method type of the given method descriptor
1201 * (JVMS {@jvms 4.3.3}). This method is a convenience method for
1202 * {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
1203 * Any class or interface name embedded in the descriptor string will be
1204 * resolved by the given loader (or if it is {@code null}, on the system class loader).
1205 *
1206 * @apiNote
1207 * It is possible to encounter method types that have valid descriptors but
1208 * cannot be constructed by this method, because their component types are
1209 * not visible from a common class loader.
1210 * <p>
1211 * This method is included for the benefit of applications that must
1212 * generate bytecodes that process method handles and {@code invokedynamic}.
1213 * @param descriptor a method descriptor string
1214 * @param loader the class loader in which to look up the types
1215 * @return a method type of the given method descriptor
1216 * @throws NullPointerException if the string is {@code null}
1217 * @throws IllegalArgumentException if the string is not a method descriptor
1218 * @throws TypeNotPresentException if a named type cannot be found
1219 * @throws SecurityException if the security manager is present and
1220 * {@code loader} is {@code null} and the caller does not have the
1221 * {@link RuntimePermission}{@code ("getClassLoader")}
1222 * @jvms 4.3.3 Method Descriptors
1223 */
1224 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader)
1225 throws IllegalArgumentException, TypeNotPresentException
1226 {
1227 if (loader == null) {
1228 @SuppressWarnings("removal")
1229 SecurityManager sm = System.getSecurityManager();
1230 if (sm != null) {
1231 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
1232 }
1233 }
1234 return fromDescriptor(descriptor,
1235 (loader == null) ? ClassLoader.getSystemClassLoader() : loader);
1236 }
1237
1238 /**
1239 * Same as {@link #fromMethodDescriptorString(String, ClassLoader)}, but
1240 * {@code null} ClassLoader means the bootstrap loader is used here.
1241 * <p>
1242 * IMPORTANT: This method is preferable for JDK internal use as it more
1243 * correctly interprets {@code null} ClassLoader than
1244 * {@link #fromMethodDescriptorString(String, ClassLoader)}.
1245 * Use of this method also avoids early initialization issues when system
1246 * ClassLoader is not initialized yet.
1247 */
1248 static MethodType fromDescriptor(String descriptor, ClassLoader loader)
1249 throws IllegalArgumentException, TypeNotPresentException
1250 {
1251 if (!descriptor.startsWith("(") || // also generates NPE if needed
1252 descriptor.indexOf(')') < 0 ||
1253 descriptor.indexOf('.') >= 0)
1254 throw newIllegalArgumentException("not a method descriptor: "+descriptor);
1255 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader);
1256 Class<?> rtype = types.remove(types.size() - 1);
1257 Class<?>[] ptypes = listToArray(types);
1258 return methodType(rtype, ptypes, true);
1259 }
1260
1261 /**
1262 * {@return the descriptor string for this method type} This method
1263 * is equivalent to calling {@link #descriptorString() MethodType::descriptorString}.
1264 *
1265 * @apiNote
1266 * This is not a strict inverse of {@link #fromMethodDescriptorString
1267 * fromMethodDescriptorString} which requires a method type descriptor
1268 * (JVMS {@jvms 4.3.3}) and a suitable class loader argument.
1269 * Two distinct {@code MethodType} objects can have an identical
1270 * descriptor string as distinct classes can have the same name
1271 * but different class loaders.
1272 *
1273 * <p>
1274 * This method is included for the benefit of applications that must
1275 * generate bytecodes that process method handles and {@code invokedynamic}.
1276 * @jvms 4.3.3 Method Descriptors
1277 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
1278 */
1279 public String toMethodDescriptorString() {
1280 String desc = methodDescriptor;
1281 if (desc == null) {
1282 desc = BytecodeDescriptor.unparseMethod(this.rtype, this.ptypes);
1283 methodDescriptor = desc;
1284 }
1285 return desc;
1286 }
1287
1288 /**
1289 * {@return the descriptor string for this method type}
1290 *
1291 * <p>
1292 * If this method type can be {@linkplain ##descriptor described nominally},
1293 * then the result is a method type descriptor (JVMS {@jvms 4.3.3}).
1294 * {@link MethodTypeDesc MethodTypeDesc} for this method type
1295 * can be produced by calling {@link MethodTypeDesc#ofDescriptor(String)
1296 * MethodTypeDesc::ofDescriptor} with the result descriptor string.
1297 * <p>
1298 * If this method type cannot be {@linkplain ##descriptor described nominally}
1299 * and the result is a string of the form:
1300 * <blockquote>{@code "(<parameter-descriptors>)<return-descriptor>"}</blockquote>
1301 * where {@code <parameter-descriptors>} is the concatenation of the
1302 * {@linkplain Class#descriptorString() descriptor string} of all
1303 * of the parameter types and the {@linkplain Class#descriptorString() descriptor string}
1304 * of the return type. No {@link java.lang.constant.MethodTypeDesc MethodTypeDesc}
1305 * can be produced from the result string.
1306 *
1307 * @since 12
1308 * @jvms 4.3.3 Method Descriptors
1309 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
1310 */
1311 @Override
1312 public String descriptorString() {
1313 return toMethodDescriptorString();
1314 }
1315
1316 /*non-public*/
1317 static String toFieldDescriptorString(Class<?> cls) {
1318 return BytecodeDescriptor.unparse(cls);
1319 }
1320
1321 /**
1322 * Returns a nominal descriptor for this instance, if one can be
1323 * constructed, or an empty {@link Optional} if one cannot be.
1324 *
1325 * @return An {@link Optional} containing the resulting nominal descriptor,
1326 * or an empty {@link Optional} if one cannot be constructed.
1327 * @since 12
1328 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
1329 */
1330 @Override
1331 public Optional<MethodTypeDesc> describeConstable() {
1332 try {
1333 return Optional.of(MethodTypeDesc.of(returnType().describeConstable().orElseThrow(),
1334 Stream.of(parameterArray())
1335 .map(p -> p.describeConstable().orElseThrow())
1336 .toArray(ClassDesc[]::new)));
1337 }
1338 catch (NoSuchElementException e) {
1339 return Optional.empty();
1340 }
1341 }
1342
1343 /// Serialization.
1344
1345 /**
1346 * There are no serializable fields for {@code MethodType}.
1347 */
1348 @java.io.Serial
1349 private static final java.io.ObjectStreamField[] serialPersistentFields = { };
1350
1351 /**
1352 * Save the {@code MethodType} instance to a stream.
1353 *
1354 * @serialData
1355 * For portability, the serialized format does not refer to named fields.
1356 * Instead, the return type and parameter type arrays are written directly
1357 * from the {@code writeObject} method, using two calls to {@code s.writeObject}
1358 * as follows:
1359 * <blockquote><pre>{@code
1360 s.writeObject(this.returnType());
1361 s.writeObject(this.parameterArray());
1362 * }</pre></blockquote>
1363 * <p>
1364 * The deserialized field values are checked as if they were
1365 * provided to the factory method {@link #methodType(Class,Class[]) methodType}.
1366 * For example, null values, or {@code void} parameter types,
1367 * will lead to exceptions during deserialization.
1368 * @param s the stream to write the object to
1369 * @throws java.io.IOException if there is a problem writing the object
1370 */
1371 @java.io.Serial
1372 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
1373 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array
1374 s.writeObject(returnType());
1375 s.writeObject(parameterArray());
1376 }
1377
1378 /**
1379 * Reconstitute the {@code MethodType} instance from a stream (that is,
1380 * deserialize it).
1381 * This instance is a scratch object with bogus final fields.
1382 * It provides the parameters to the factory method called by
1383 * {@link #readResolve readResolve}.
1384 * After that call it is discarded.
1385 * @param s the stream to read the object from
1386 * @throws java.io.IOException if there is a problem reading the object
1387 * @throws ClassNotFoundException if one of the component classes cannot be resolved
1388 * @see #readResolve
1389 * @see #writeObject
1390 */
1391 @java.io.Serial
1392 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
1393 // Assign defaults in case this object escapes
1394 UNSAFE.putReference(this, OffsetHolder.rtypeOffset, void.class);
1395 UNSAFE.putReference(this, OffsetHolder.ptypesOffset, NO_PTYPES);
1396
1397 s.defaultReadObject(); // requires serialPersistentFields to be an empty array
1398
1399 Class<?> returnType = (Class<?>) s.readObject();
1400 Class<?>[] parameterArray = (Class<?>[]) s.readObject();
1401
1402 // Verify all operands, and make sure ptypes is unshared
1403 // Cache the new MethodType for readResolve
1404 wrapAlt = new MethodType[]{MethodType.methodType(returnType, parameterArray)};
1405 }
1406
1407 // Support for resetting final fields while deserializing. Implement Holder
1408 // pattern to make the rarely needed offset calculation lazy.
1409 private static class OffsetHolder {
1410 static final long rtypeOffset
1411 = UNSAFE.objectFieldOffset(MethodType.class, "rtype");
1412
1413 static final long ptypesOffset
1414 = UNSAFE.objectFieldOffset(MethodType.class, "ptypes");
1415 }
1416
1417 /**
1418 * Resolves and initializes a {@code MethodType} object
1419 * after serialization.
1420 * @return the fully initialized {@code MethodType} object
1421 */
1422 @java.io.Serial
1423 private Object readResolve() {
1424 // Do not use a trusted path for deserialization:
1425 // return makeImpl(rtype, ptypes, true);
1426 // Verify all operands, and make sure ptypes is unshared:
1427 // Return a new validated MethodType for the rtype and ptypes passed from readObject.
1428 MethodType mt = ((MethodType[])wrapAlt)[0];
1429 wrapAlt = null;
1430 return mt;
1431 }
1432
1433 static HashMap<MethodType,MethodType> archive(Archiver archiver) {
1434 HashMap<MethodType,MethodType> archivedSet = new HashMap<>();
1435
1436 for (Iterator<MethodType> i = internTable.iterator(); i.hasNext(); ) {
1437 MethodType t = i.next();
1438 MethodType a = archiver.clean(t);
1439 if (a != null) {
1440 archivedSet.put(a, a);
1441 }
1442 }
1443
1444 return archivedSet;
1445 }
1446
1447 static class Archiver {
1448 ArrayList<MethodType> archived = new ArrayList<>();
1449
1450 MethodType clean(MethodType t) {
1451 if (t == null || t.form == null) { // HACK!
1452 return null;
1453 }
1454 if (archived.contains(t)) {
1455 return t;
1456 }
1457
1458 archived.add(t);
1459 return t;
1460 }
1461 }
1462
1463 // This is called from C code.
1464 static void dumpSharedArchive() {
1465 Archiver archiver = new Archiver();
1466
1467 MethodType[] objectOnlyTypesCopy = new MethodType[objectOnlyTypes.length];
1468 for (int i = 0; i < objectOnlyTypes.length; i++) {
1469 MethodType t = archiver.clean(objectOnlyTypes[i]);
1470 if (t != null) {
1471 objectOnlyTypesCopy[i] = t;
1472 }
1473 }
1474
1475 archivedObjects = new Object[2];
1476 archivedObjects[0] = archive(archiver);
1477 archivedObjects[1] = objectOnlyTypesCopy;
1478
1479 DirectMethodHandle.dumpSharedArchive();
1480 LambdaForm.NamedFunction.dumpSharedArchive();
1481 }
1482 }