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.util.Arrays;
32 import java.util.Collections;
33 import java.util.function.Supplier;
34 import java.util.List;
35 import java.util.Map;
36 import java.util.Objects;
37 import java.util.Optional;
38 import java.util.StringJoiner;
39 import java.util.concurrent.ConcurrentHashMap;
40
41 import jdk.internal.util.ReferencedKeySet;
42 import jdk.internal.util.ReferenceKey;
43 import jdk.internal.vm.annotation.Stable;
44 import sun.invoke.util.BytecodeDescriptor;
45 import sun.invoke.util.VerifyType;
46 import sun.invoke.util.Wrapper;
47
48 import static java.lang.invoke.MethodHandleStatics.UNSAFE;
49 import static java.lang.invoke.MethodHandleStatics.newIllegalArgumentException;
50
51 /**
52 * A method type represents the arguments and return type accepted and
53 * returned by a method handle, or the arguments and return type passed
54 * and expected by a method handle caller. Method types must be properly
55 * matched between a method handle and all its callers,
56 * and the JVM's operations enforce this matching at, specifically
57 * during calls to {@link MethodHandle#invokeExact MethodHandle.invokeExact}
58 * and {@link MethodHandle#invoke MethodHandle.invoke}, and during execution
59 * of {@code invokedynamic} instructions.
60 * <p>
61 * The structure is a return type accompanied by any number of parameter types.
62 * The types (primitive, {@code void}, and reference) are represented by {@link Class} objects.
63 * (For ease of exposition, we treat {@code void} as if it were a type.
64 * In fact, it denotes the absence of a return type.)
65 * <p>
66 * All instances of {@code MethodType} are immutable.
67 * Two instances are completely interchangeable if they compare equal.
68 * Equality depends on pairwise correspondence of the return and parameter types and on nothing else.
69 * <p>
70 * This type can be created only by factory methods.
71 * All factory methods may cache values, though caching is not guaranteed.
72 * Some factory methods are static, while others are virtual methods which
73 * modify precursor method types, e.g., by changing a selected parameter.
74 * <p>
75 * Factory methods which operate on groups of parameter types
76 * are systematically presented in two versions, so that both Java arrays and
77 * Java lists can be used to work with groups of parameter types.
78 * The query methods {@code parameterArray} and {@code parameterList}
79 * also provide a choice between arrays and lists.
80 * <p>
81 * {@code MethodType} objects are sometimes derived from bytecode instructions
82 * such as {@code invokedynamic}, specifically from the type descriptor strings associated
83 * with the instructions in a class file's constant pool.
84 * <p>
85 * Like classes and strings, method types can also be represented directly
86 * in a class file's constant pool as constants.
87 * A method type may be loaded by an {@code ldc} instruction which refers
88 * to a suitable {@code CONSTANT_MethodType} constant pool entry.
89 * The entry refers to a {@code CONSTANT_Utf8} spelling for the descriptor string.
90 * (For full details on method type constants, see sections {@jvms
91 * 4.4.8} and {@jvms 5.4.3.5} of the Java Virtual Machine
92 * Specification.)
93 * <p>
94 * When the JVM materializes a {@code MethodType} from a descriptor string,
95 * all classes named in the descriptor must be accessible, and will be loaded.
96 * (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.)
97 * This loading may occur at any time before the {@code MethodType} object is first derived.
98 * <p>
99 * <b><a id="descriptor">Nominal Descriptors</a></b>
100 * <p>
101 * A {@code MethodType} can be described in {@linkplain MethodTypeDesc nominal form}
102 * if and only if all of the parameter types and return type can be described
103 * with a {@link Class#describeConstable() nominal descriptor} represented by
104 * {@link ClassDesc}. If a method type can be described nominally, then:
105 * <ul>
106 * <li>The method type has a {@link MethodTypeDesc nominal descriptor}
107 * returned by {@link #describeConstable() MethodType::describeConstable}.</li>
108 * <li>The descriptor string returned by
109 * {@link #descriptorString() MethodType::descriptorString} or
110 * {@link #toMethodDescriptorString() MethodType::toMethodDescriptorString}
111 * for the method type is a method descriptor (JVMS {@jvms 4.3.3}).</li>
112 * </ul>
113 * <p>
114 * If any of the parameter types or return type cannot be described
115 * nominally, i.e. {@link Class#describeConstable() Class::describeConstable}
116 * returns an empty optional for that type,
117 * then the method type cannot be described nominally:
118 * <ul>
119 * <li>The method type has no {@link MethodTypeDesc nominal descriptor} and
120 * {@link #describeConstable() MethodType::describeConstable} returns
121 * an empty optional.</li>
122 * <li>The descriptor string returned by
123 * {@link #descriptorString() MethodType::descriptorString} or
124 * {@link #toMethodDescriptorString() MethodType::toMethodDescriptorString}
125 * for the method type is not a type descriptor.</li>
126 * </ul>
127 *
128 * @author John Rose, JSR 292 EG
129 * @since 1.7
130 */
131 public final
132 class MethodType
133 implements Constable,
134 TypeDescriptor.OfMethod<Class<?>, MethodType>,
135 java.io.Serializable {
136 @java.io.Serial
137 private static final long serialVersionUID = 292L; // {rtype, {ptype...}}
138
139 // The rtype and ptypes fields define the structural identity of the method type:
140 private final @Stable Class<?> rtype;
141 private final @Stable Class<?>[] ptypes;
142
143 // The remaining fields are caches of various sorts:
144 private @Stable MethodTypeForm form; // erased form, plus cached data about primitives
145 private @Stable Object wrapAlt; // alternative wrapped/unwrapped version and
146 // private communication for readObject and readResolve
147 private @Stable Invokers invokers; // cache of handy higher-order adapters
148 private @Stable String methodDescriptor; // cache for toMethodDescriptorString
149
150 /**
151 * Constructor that performs no copying or validation.
152 * Should only be called from the factory method makeImpl
153 */
154 private MethodType(Class<?> rtype, Class<?>[] ptypes) {
155 this.rtype = rtype;
156 this.ptypes = ptypes;
157 }
158
159 /*trusted*/ MethodTypeForm form() { return form; }
160 /*trusted*/ Class<?> rtype() { return rtype; }
161 /*trusted*/ Class<?>[] ptypes() { return ptypes; }
162
163 void setForm(MethodTypeForm f) { form = f; }
164
165 /** This number, mandated by the JVM spec as 255,
166 * is the maximum number of <em>slots</em>
167 * that any Java method can receive in its argument list.
168 * It limits both JVM signatures and method type objects.
169 * The longest possible invocation will look like
170 * {@code staticMethod(arg1, arg2, ..., arg255)} or
171 * {@code x.virtualMethod(arg1, arg2, ..., arg254)}.
172 */
173 /*non-public*/
174 static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec.
175
176 /** This number is the maximum arity of a method handle, 254.
177 * It is derived from the absolute JVM-imposed arity by subtracting one,
178 * which is the slot occupied by the method handle itself at the
179 * beginning of the argument list used to invoke the method handle.
180 * The longest possible invocation will look like
181 * {@code mh.invoke(arg1, arg2, ..., arg254)}.
182 */
183 // Issue: Should we allow MH.invokeWithArguments to go to the full 255?
184 /*non-public*/
185 static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver
186
187 /** This number is the maximum arity of a method handle invoker, 253.
188 * It is derived from the absolute JVM-imposed arity by subtracting two,
189 * which are the slots occupied by invoke method handle, and the
190 * target method handle, which are both at the beginning of the argument
191 * list used to invoke the target method handle.
192 * The longest possible invocation will look like
193 * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}.
194 */
195 /*non-public*/
196 static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker
197
198 /** Return number of extra slots (count of long/double args). */
199 private static int checkPtypes(Class<?>[] ptypes) {
200 int slots = 0;
201 for (Class<?> ptype : ptypes) {
202 Objects.requireNonNull(ptype);
203 if (ptype == void.class)
204 throw newIllegalArgumentException("parameter type cannot be void");
205 if (ptype == double.class || ptype == long.class) {
206 slots++;
207 }
208 }
209 checkSlotCount(ptypes.length + slots);
210 return slots;
211 }
212
213 static {
214 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work:
215 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0);
216 }
217 static void checkSlotCount(int count) {
218 if ((count & MAX_JVM_ARITY) != count)
219 throw newIllegalArgumentException("bad parameter count "+count);
220 }
221 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) {
222 if (num instanceof Integer) num = "bad index: "+num;
223 return new IndexOutOfBoundsException(num.toString());
224 }
225
226 static final ReferencedKeySet<MethodType> internTable =
227 ReferencedKeySet.create(false, new Supplier<>() {
228 @Override
229 public Map<ReferenceKey<MethodType>, ReferenceKey<MethodType>> get() {
230 return new ConcurrentHashMap<>(512);
231 }
232 });
233
234 static final Class<?>[] NO_PTYPES = {};
235
236 /**
237 * Finds or creates an instance of the given method type.
238 * @param rtype the return type
239 * @param ptypes the parameter types
240 * @return a method type with the given components
241 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
242 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
243 */
244 public static MethodType methodType(Class<?> rtype, Class<?>[] ptypes) {
245 return methodType(rtype, ptypes, false);
246 }
247
248 /**
249 * Finds or creates a method type with the given components.
250 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
251 * @param rtype the return type
252 * @param ptypes the parameter types
253 * @return a method type with the given components
254 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
255 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
256 */
257 public static MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) {
258 boolean notrust = false; // random List impl. could return evil ptypes array
259 return methodType(rtype, listToArray(ptypes), notrust);
260 }
261
262 private static Class<?>[] listToArray(List<Class<?>> ptypes) {
263 // sanity check the size before the toArray call, since size might be huge
264 checkSlotCount(ptypes.size());
265 return ptypes.toArray(NO_PTYPES);
266 }
267
268 /**
269 * Finds or creates a method type with the given components.
270 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
271 * The leading parameter type is prepended to the remaining array.
272 * @param rtype the return type
273 * @param ptype0 the first parameter type
274 * @param ptypes the remaining parameter types
275 * @return a method type with the given components
276 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null
277 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class}
278 */
279 public static MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) {
280 int len = ptypes.length;
281 if (rtype == Object.class && ptype0 == Object.class) {
282 if (len == 0) {
283 return genericMethodType(1, false);
284 }
285 if (isAllObject(ptypes, len - 1)) {
286 Class<?> lastParam = ptypes[len - 1];
287 if (lastParam == Object.class) {
288 return genericMethodType(len + 1, false);
289 } else if (lastParam == Object[].class) {
290 return genericMethodType(len, true);
291 }
292 }
293 }
294 Class<?>[] ptypes1 = new Class<?>[1 + len];
295 ptypes1[0] = ptype0;
296 System.arraycopy(ptypes, 0, ptypes1, 1, len);
297 return makeImpl(rtype, ptypes1, true);
298 }
299
300 /**
301 * Finds or creates a method type with the given components.
302 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
303 * The resulting method has no parameter types.
304 * @param rtype the return type
305 * @return a method type with the given return value
306 * @throws NullPointerException if {@code rtype} is null
307 */
308 public static MethodType methodType(Class<?> rtype) {
309 if (rtype == Object.class) {
310 return genericMethodType(0, false);
311 }
312 return makeImpl(rtype, NO_PTYPES, true);
313 }
314
315 /**
316 * Finds or creates a method type with the given components.
317 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
318 * The resulting method has the single given parameter type.
319 * @param rtype the return type
320 * @param ptype0 the parameter type
321 * @return a method type with the given return value and parameter type
322 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null
323 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class}
324 */
325 public static MethodType methodType(Class<?> rtype, Class<?> ptype0) {
326 if (rtype == Object.class) {
327 if (ptype0 == Object.class) {
328 return genericMethodType(1, false);
329 } else if (ptype0 == Object[].class) {
330 return genericMethodType(0, true);
331 }
332 }
333 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true);
334 }
335
336 /**
337 * Finds or creates a method type with the given components.
338 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
339 * The resulting method has the same parameter types as {@code ptypes},
340 * and the specified return type.
341 * @param rtype the return type
342 * @param ptypes the method type which supplies the parameter types
343 * @return a method type with the given components
344 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null
345 */
346 public static MethodType methodType(Class<?> rtype, MethodType ptypes) {
347 return methodType(rtype, ptypes.ptypes, true);
348 }
349
350 private static boolean isAllObject(Class<?>[] ptypes, int to) {
351 for (int i = 0; i < to; i++) {
352 if (ptypes[i] != Object.class) {
353 return false;
354 }
355 }
356 return true;
357 }
358
359 /*trusted*/
360 static MethodType methodType(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
361 if (rtype == Object.class) {
362 int last = ptypes.length - 1;
363 if (last < 0) {
364 return genericMethodType(0, false);
365 }
366 if (isAllObject(ptypes, last)) {
367 Class<?> lastParam = ptypes[last];
368 if (lastParam == Object.class) {
369 return genericMethodType(last + 1, false);
370 } else if (lastParam == Object[].class) {
371 return genericMethodType(last, true);
372 }
373 }
374 }
375 return makeImpl(rtype, ptypes, trusted);
376 }
377
378 /**
379 * Sole factory method to find or create an interned method type. Will perform
380 * input validation on behalf of factory methods
381 *
382 * @param rtype desired return type
383 * @param ptypes desired parameter types
384 * @param trusted whether the ptypes can be used without cloning
385 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
386 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
387 * @return the unique method type of the desired structure
388 */
389 private static MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
390 if (ptypes.length == 0) {
391 ptypes = NO_PTYPES; trusted = true;
392 }
393 MethodType primordialMT = new MethodType(rtype, ptypes);
394 MethodType mt = internTable.get(primordialMT);
395 if (mt != null)
396 return mt;
397
398 // promote the object to the Real Thing, and reprobe
399 Objects.requireNonNull(rtype);
400 if (trusted) {
401 MethodType.checkPtypes(ptypes);
402 mt = primordialMT;
403 } else {
404 // Make defensive copy then validate
405 ptypes = Arrays.copyOf(ptypes, ptypes.length);
406 MethodType.checkPtypes(ptypes);
407 mt = new MethodType(rtype, ptypes);
408 }
409 mt.form = MethodTypeForm.findForm(mt);
410 return internTable.intern(mt);
411 }
412
413 private static final @Stable MethodType[] objectOnlyTypes = new MethodType[20];
414
415 /**
416 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array.
417 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
418 * All parameters and the return type will be {@code Object},
419 * except the final array parameter if any, which will be {@code Object[]}.
420 * @param objectArgCount number of parameters (excluding the final array parameter if any)
421 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]}
422 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments
423 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true)
424 * @see #genericMethodType(int)
425 */
426 public static MethodType genericMethodType(int objectArgCount, boolean finalArray) {
427 MethodType mt;
428 checkSlotCount(objectArgCount);
429 int ivarargs = (!finalArray ? 0 : 1);
430 int ootIndex = objectArgCount*2 + ivarargs;
431 if (ootIndex < objectOnlyTypes.length) {
432 mt = objectOnlyTypes[ootIndex];
433 if (mt != null) return mt;
434 }
435 Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs];
436 Arrays.fill(ptypes, Object.class);
437 if (ivarargs != 0) ptypes[objectArgCount] = Object[].class;
438 mt = makeImpl(Object.class, ptypes, true);
439 if (ootIndex < objectOnlyTypes.length) {
440 objectOnlyTypes[ootIndex] = mt; // cache it here also!
441 }
442 return mt;
443 }
444
445 /**
446 * Finds or creates a method type whose components are all {@code Object}.
447 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
448 * All parameters and the return type will be Object.
449 * @param objectArgCount number of parameters
450 * @return a generally applicable method type, for all calls of the given argument count
451 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255
452 * @see #genericMethodType(int, boolean)
453 */
454 public static MethodType genericMethodType(int objectArgCount) {
455 return genericMethodType(objectArgCount, false);
456 }
457
458 /**
459 * Finds or creates a method type with a single different parameter type.
460 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
461 * @param num the index (zero-based) of the parameter type to change
462 * @param nptype a new parameter type to replace the old one with
463 * @return the same type, except with the selected parameter changed
464 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
465 * @throws IllegalArgumentException if {@code nptype} is {@code void.class}
466 * @throws NullPointerException if {@code nptype} is null
467 */
468 public MethodType changeParameterType(int num, Class<?> nptype) {
469 if (parameterType(num) == nptype) return this;
470 Class<?>[] nptypes = ptypes.clone();
471 nptypes[num] = nptype;
472 return makeImpl(rtype, nptypes, true);
473 }
474
475 /**
476 * Finds or creates a method type with additional parameter types.
477 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
478 * @param num the position (zero-based) of the inserted parameter type(s)
479 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
480 * @return the same type, except with the selected parameter(s) inserted
481 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
482 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
483 * or if the resulting method type would have more than 255 parameter slots
484 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
485 */
486 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) {
487 int len = ptypes.length;
488 if (num < 0 || num > len)
489 throw newIndexOutOfBoundsException(num);
490 int ins = checkPtypes(ptypesToInsert);
491 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins);
492 int ilen = ptypesToInsert.length;
493 if (ilen == 0) return this;
494 Class<?>[] nptypes = new Class<?>[len + ilen];
495 if (num > 0) {
496 System.arraycopy(ptypes, 0, nptypes, 0, num);
497 }
498 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen);
499 if (num < len) {
500 System.arraycopy(ptypes, num, nptypes, num+ilen, len-num);
501 }
502 return makeImpl(rtype, nptypes, true);
503 }
504
505 /**
506 * Finds or creates a method type with additional parameter types.
507 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
508 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
509 * @return the same type, except with the selected parameter(s) appended
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 appendParameterTypes(Class<?>... ptypesToInsert) {
515 return insertParameterTypes(parameterCount(), ptypesToInsert);
516 }
517
518 /**
519 * Finds or creates a method type with additional parameter types.
520 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
521 * @param num the position (zero-based) of the inserted parameter type(s)
522 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
523 * @return the same type, except with the selected parameter(s) inserted
524 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
525 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
526 * or if the resulting method type would have more than 255 parameter slots
527 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
528 */
529 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) {
530 return insertParameterTypes(num, listToArray(ptypesToInsert));
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(List<Class<?>> ptypesToInsert) {
543 return insertParameterTypes(parameterCount(), ptypesToInsert);
544 }
545
546 /**
547 * Finds or creates a method type with modified parameter types.
548 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
549 * @param start the position (zero-based) of the first replaced parameter type(s)
550 * @param end the position (zero-based) after the last replaced parameter type(s)
551 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
552 * @return the same type, except with the selected parameter(s) replaced
553 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
554 * or if {@code end} is negative or greater than {@code parameterCount()}
555 * or if {@code start} is greater than {@code end}
556 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
557 * or if the resulting method type would have more than 255 parameter slots
558 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
559 */
560 /*non-public*/
561 MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) {
562 if (start == end)
563 return insertParameterTypes(start, ptypesToInsert);
564 int len = ptypes.length;
565 if (!(0 <= start && start <= end && end <= len))
566 throw newIndexOutOfBoundsException("start="+start+" end="+end);
567 int ilen = ptypesToInsert.length;
568 if (ilen == 0)
569 return dropParameterTypes(start, end);
570 return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert);
571 }
572
573 /** Replace the last arrayLength parameter types with the component type of arrayType.
574 * @param arrayType any array type
575 * @param pos position at which to spread
576 * @param arrayLength the number of parameter types to change
577 * @return the resulting type
578 */
579 /*non-public*/
580 MethodType asSpreaderType(Class<?> arrayType, int pos, int arrayLength) {
581 assert(parameterCount() >= arrayLength);
582 int spreadPos = pos;
583 if (arrayLength == 0) return this; // nothing to change
584 if (arrayType == Object[].class) {
585 if (isGeneric()) return this; // nothing to change
586 if (spreadPos == 0) {
587 // no leading arguments to preserve; go generic
588 MethodType res = genericMethodType(arrayLength);
589 if (rtype != Object.class) {
590 res = res.changeReturnType(rtype);
591 }
592 return res;
593 }
594 }
595 Class<?> elemType = arrayType.getComponentType();
596 assert(elemType != null);
597 for (int i = spreadPos; i < spreadPos + arrayLength; i++) {
598 if (ptypes[i] != elemType) {
599 Class<?>[] fixedPtypes = ptypes.clone();
600 Arrays.fill(fixedPtypes, i, spreadPos + arrayLength, elemType);
601 return methodType(rtype, fixedPtypes);
602 }
603 }
604 return this; // arguments check out; no change
605 }
606
607 /** Return the leading parameter type, which must exist and be a reference.
608 * @return the leading parameter type, after error checks
609 */
610 /*non-public*/
611 Class<?> leadingReferenceParameter() {
612 Class<?> ptype;
613 if (ptypes.length == 0 ||
614 (ptype = ptypes[0]).isPrimitive())
615 throw newIllegalArgumentException("no leading reference parameter");
616 return ptype;
617 }
618
619 /** Delete the last parameter type and replace it with arrayLength copies of the component type of arrayType.
620 * @param arrayType any array type
621 * @param pos position at which to insert parameters
622 * @param arrayLength the number of parameter types to insert
623 * @return the resulting type
624 */
625 /*non-public*/
626 MethodType asCollectorType(Class<?> arrayType, int pos, int arrayLength) {
627 assert(parameterCount() >= 1);
628 assert(pos < ptypes.length);
629 assert(ptypes[pos].isAssignableFrom(arrayType));
630 MethodType res;
631 if (arrayType == Object[].class) {
632 res = genericMethodType(arrayLength);
633 if (rtype != Object.class) {
634 res = res.changeReturnType(rtype);
635 }
636 } else {
637 Class<?> elemType = arrayType.getComponentType();
638 assert(elemType != null);
639 res = methodType(rtype, Collections.nCopies(arrayLength, elemType));
640 }
641 if (ptypes.length == 1) {
642 return res;
643 } else {
644 // insert after (if need be), then before
645 if (pos < ptypes.length - 1) {
646 res = res.insertParameterTypes(arrayLength, Arrays.copyOfRange(ptypes, pos + 1, ptypes.length));
647 }
648 return res.insertParameterTypes(0, Arrays.copyOf(ptypes, pos));
649 }
650 }
651
652 /**
653 * Finds or creates a method type with some parameter types omitted.
654 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
655 * @param start the index (zero-based) of the first parameter type to remove
656 * @param end the index (greater than {@code start}) of the first parameter type after not to remove
657 * @return the same type, except with the selected parameter(s) removed
658 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
659 * or if {@code end} is negative or greater than {@code parameterCount()}
660 * or if {@code start} is greater than {@code end}
661 */
662 public MethodType dropParameterTypes(int start, int end) {
663 int len = ptypes.length;
664 if (!(0 <= start && start <= end && end <= len))
665 throw newIndexOutOfBoundsException("start="+start+" end="+end);
666 if (start == end) return this;
667 Class<?>[] nptypes;
668 if (start == 0) {
669 if (end == len) {
670 // drop all parameters
671 nptypes = NO_PTYPES;
672 } else {
673 // drop initial parameter(s)
674 nptypes = Arrays.copyOfRange(ptypes, end, len);
675 }
676 } else {
677 if (end == len) {
678 // drop trailing parameter(s)
679 nptypes = Arrays.copyOfRange(ptypes, 0, start);
680 } else {
681 int tail = len - end;
682 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail);
683 System.arraycopy(ptypes, end, nptypes, start, tail);
684 }
685 }
686 return methodType(rtype, nptypes, true);
687 }
688
689 /**
690 * Finds or creates a method type with a different return type.
691 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
692 * @param nrtype a return parameter type to replace the old one with
693 * @return the same type, except with the return type change
694 * @throws NullPointerException if {@code nrtype} is null
695 */
696 public MethodType changeReturnType(Class<?> nrtype) {
697 if (returnType() == nrtype) return this;
698 return methodType(nrtype, ptypes, true);
699 }
700
701 /**
702 * Reports if this type contains a primitive argument or return value.
703 * The return type {@code void} counts as a primitive.
704 * @return true if any of the types are primitives
705 */
706 public boolean hasPrimitives() {
707 return form.hasPrimitives();
708 }
709
710 /**
711 * Reports if this type contains a wrapper argument or return value.
712 * Wrappers are types which box primitive values, such as {@link Integer}.
713 * The reference type {@code java.lang.Void} counts as a wrapper,
714 * if it occurs as a return type.
715 * @return true if any of the types are wrappers
716 */
717 public boolean hasWrappers() {
718 return unwrap() != this;
719 }
720
721 /**
722 * Erases all reference types to {@code Object}.
723 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
724 * All primitive types (including {@code void}) will remain unchanged.
725 * @return a version of the original type with all reference types replaced
726 */
727 public MethodType erase() {
728 return form.erasedType();
729 }
730
731 /**
732 * Erases all reference types to {@code Object}, and all subword types to {@code int}.
733 * This is the reduced type polymorphism used by private methods
734 * such as {@link MethodHandle#invokeBasic invokeBasic}.
735 * @return a version of the original type with all reference and subword types replaced
736 */
737 /*non-public*/
738 MethodType basicType() {
739 return form.basicType();
740 }
741
742 private static final @Stable Class<?>[] METHOD_HANDLE_ARRAY
743 = new Class<?>[] { MethodHandle.class };
744
745 /**
746 * @return a version of the original type with MethodHandle prepended as the first argument
747 */
748 /*non-public*/
749 MethodType invokerType() {
750 return insertParameterTypes(0, METHOD_HANDLE_ARRAY);
751 }
752
753 /**
754 * Converts all types, both reference and primitive, to {@code Object}.
755 * Convenience method for {@link #genericMethodType(int) genericMethodType}.
756 * The expression {@code type.wrap().erase()} produces the same value
757 * as {@code type.generic()}.
758 * @return a version of the original type with all types replaced
759 */
760 public MethodType generic() {
761 return genericMethodType(parameterCount());
762 }
763
764 /*non-public*/
765 boolean isGeneric() {
766 return this == erase() && !hasPrimitives();
767 }
768
769 /**
770 * Converts all primitive types to their corresponding wrapper types.
771 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
772 * All reference types (including wrapper types) will remain unchanged.
773 * A {@code void} return type is changed to the type {@code java.lang.Void}.
774 * The expression {@code type.wrap().erase()} produces the same value
775 * as {@code type.generic()}.
776 * @return a version of the original type with all primitive types replaced
777 */
778 public MethodType wrap() {
779 return hasPrimitives() ? wrapWithPrims(this) : this;
780 }
781
782 /**
783 * Converts all wrapper types to their corresponding primitive types.
784 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
785 * All primitive types (including {@code void}) will remain unchanged.
786 * A return type of {@code java.lang.Void} is changed to {@code void}.
787 * @return a version of the original type with all wrapper types replaced
788 */
789 public MethodType unwrap() {
790 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this);
791 return unwrapWithNoPrims(noprims);
792 }
793
794 private static MethodType wrapWithPrims(MethodType pt) {
795 assert(pt.hasPrimitives());
796 MethodType wt = (MethodType)pt.wrapAlt;
797 if (wt == null) {
798 // fill in lazily
799 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP);
800 assert(wt != null);
801 pt.wrapAlt = wt;
802 }
803 return wt;
804 }
805
806 private static MethodType unwrapWithNoPrims(MethodType wt) {
807 assert(!wt.hasPrimitives());
808 MethodType uwt = (MethodType)wt.wrapAlt;
809 if (uwt == null) {
810 // fill in lazily
811 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP);
812 if (uwt == null)
813 uwt = wt; // type has no wrappers or prims at all
814 wt.wrapAlt = uwt;
815 }
816 return uwt;
817 }
818
819 /**
820 * Returns the parameter type at the specified index, within this method type.
821 * @param num the index (zero-based) of the desired parameter type
822 * @return the selected parameter type
823 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
824 */
825 public Class<?> parameterType(int num) {
826 return ptypes[num];
827 }
828 /**
829 * Returns the number of parameter types in this method type.
830 * @return the number of parameter types
831 */
832 public int parameterCount() {
833 return ptypes.length;
834 }
835 /**
836 * Returns the return type of this method type.
837 * @return the return type
838 */
839 public Class<?> returnType() {
840 return rtype;
841 }
842
843 /**
844 * Presents the parameter types as a list (a convenience method).
845 * The list will be immutable.
846 * @return the parameter types (as an immutable list)
847 */
848 public List<Class<?>> parameterList() {
849 return List.of(ptypes);
850 }
851
852 /**
853 * Returns the last parameter type of this method type.
854 * If this type has no parameters, the sentinel value
855 * {@code void.class} is returned instead.
856 * @apiNote
857 * <p>
858 * The sentinel value is chosen so that reflective queries can be
859 * made directly against the result value.
860 * The sentinel value cannot be confused with a real parameter,
861 * since {@code void} is never acceptable as a parameter type.
862 * For variable arity invocation modes, the expression
863 * {@link Class#getComponentType lastParameterType().getComponentType()}
864 * is useful to query the type of the "varargs" parameter.
865 * @return the last parameter type if any, else {@code void.class}
866 * @since 10
867 */
868 public Class<?> lastParameterType() {
869 int len = ptypes.length;
870 return len == 0 ? void.class : ptypes[len-1];
871 }
872
873 /**
874 * Presents the parameter types as an array (a convenience method).
875 * Changes to the array will not result in changes to the type.
876 * @return the parameter types (as a fresh copy if necessary)
877 */
878 public Class<?>[] parameterArray() {
879 return ptypes.clone();
880 }
881
882 /**
883 * Compares the specified object with this type for equality.
884 * That is, it returns {@code true} if and only if the specified object
885 * is also a method type with exactly the same parameters and return type.
886 * @param x object to compare
887 * @see Object#equals(Object)
888 */
889 @Override
890 public boolean equals(Object x) {
891 if (this == x) {
892 return true;
893 }
894 if (x instanceof MethodType mt) {
895 return equals(mt);
896 }
897 return false;
898 }
899
900 private boolean equals(MethodType that) {
901 return this.rtype == that.rtype
902 && Arrays.equals(this.ptypes, that.ptypes);
903 }
904
905 /**
906 * Returns the hash code value for this method type.
907 * It is defined to be the same as the hashcode of a List
908 * whose elements are the return type followed by the
909 * parameter types.
910 * @return the hash code value for this method type
911 * @see Object#hashCode()
912 * @see #equals(Object)
913 * @see List#hashCode()
914 */
915 @Override
916 public int hashCode() {
917 int hashCode = 31 + rtype.hashCode();
918 for (Class<?> ptype : ptypes)
919 hashCode = 31 * hashCode + ptype.hashCode();
920 return hashCode;
921 }
922
923 /**
924 * Returns a string representation of the method type,
925 * of the form {@code "(PT0,PT1...)RT"}.
926 * The string representation of a method type is a
927 * parenthesis enclosed, comma separated list of type names,
928 * followed immediately by the return type.
929 * <p>
930 * Each type is represented by its
931 * {@link java.lang.Class#getSimpleName simple name}.
932 */
933 @Override
934 public String toString() {
935 StringJoiner sj = new StringJoiner(",", "(",
936 ")" + rtype.getSimpleName());
937 for (int i = 0; i < ptypes.length; i++) {
938 sj.add(ptypes[i].getSimpleName());
939 }
940 return sj.toString();
941 }
942
943 /** True if my parameter list is effectively identical to the given full list,
944 * after skipping the given number of my own initial parameters.
945 * In other words, after disregarding {@code skipPos} parameters,
946 * my remaining parameter list is no longer than the {@code fullList}, and
947 * is equal to the same-length initial sublist of {@code fullList}.
948 */
949 /*non-public*/
950 boolean effectivelyIdenticalParameters(int skipPos, List<Class<?>> fullList) {
951 int myLen = ptypes.length, fullLen = fullList.size();
952 if (skipPos > myLen || myLen - skipPos > fullLen)
953 return false;
954 List<Class<?>> myList = Arrays.asList(ptypes);
955 if (skipPos != 0) {
956 myList = myList.subList(skipPos, myLen);
957 myLen -= skipPos;
958 }
959 if (fullLen == myLen)
960 return myList.equals(fullList);
961 else
962 return myList.equals(fullList.subList(0, myLen));
963 }
964
965 /** True if the old return type can always be viewed (w/o casting) under new return type,
966 * and the new parameters can be viewed (w/o casting) under the old parameter types.
967 */
968 /*non-public*/
969 boolean isViewableAs(MethodType newType, boolean keepInterfaces) {
970 if (!VerifyType.isNullConversion(returnType(), newType.returnType(), keepInterfaces))
971 return false;
972 if (form == newType.form && form.erasedType == this)
973 return true; // my reference parameters are all Object
974 if (ptypes == newType.ptypes)
975 return true;
976 int argc = parameterCount();
977 if (argc != newType.parameterCount())
978 return false;
979 for (int i = 0; i < argc; i++) {
980 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i), keepInterfaces))
981 return false;
982 }
983 return true;
984 }
985 /*non-public*/
986 boolean isConvertibleTo(MethodType newType) {
987 MethodTypeForm oldForm = this.form();
988 MethodTypeForm newForm = newType.form();
989 if (oldForm == newForm)
990 // same parameter count, same primitive/object mix
991 return true;
992 if (!canConvert(returnType(), newType.returnType()))
993 return false;
994 Class<?>[] srcTypes = newType.ptypes;
995 Class<?>[] dstTypes = ptypes;
996 if (srcTypes == dstTypes)
997 return true;
998 int argc;
999 if ((argc = srcTypes.length) != dstTypes.length)
1000 return false;
1001 if (argc <= 1) {
1002 if (argc == 1 && !canConvert(srcTypes[0], dstTypes[0]))
1003 return false;
1004 return true;
1005 }
1006 if ((!oldForm.hasPrimitives() && oldForm.erasedType == this) ||
1007 (!newForm.hasPrimitives() && newForm.erasedType == newType)) {
1008 // Somewhat complicated test to avoid a loop of 2 or more trips.
1009 // If either type has only Object parameters, we know we can convert.
1010 assert(canConvertParameters(srcTypes, dstTypes));
1011 return true;
1012 }
1013 return canConvertParameters(srcTypes, dstTypes);
1014 }
1015
1016 /** Returns true if MHs.explicitCastArguments produces the same result as MH.asType.
1017 * If the type conversion is impossible for either, the result should be false.
1018 */
1019 /*non-public*/
1020 boolean explicitCastEquivalentToAsType(MethodType newType) {
1021 if (this == newType) return true;
1022 if (!explicitCastEquivalentToAsType(rtype, newType.rtype)) {
1023 return false;
1024 }
1025 Class<?>[] srcTypes = newType.ptypes;
1026 Class<?>[] dstTypes = ptypes;
1027 if (dstTypes == srcTypes) {
1028 return true;
1029 }
1030 assert(dstTypes.length == srcTypes.length);
1031 for (int i = 0; i < dstTypes.length; i++) {
1032 if (!explicitCastEquivalentToAsType(srcTypes[i], dstTypes[i])) {
1033 return false;
1034 }
1035 }
1036 return true;
1037 }
1038
1039 /** Reports true if the src can be converted to the dst, by both asType and MHs.eCE,
1040 * and with the same effect.
1041 * MHs.eCA has the following "upgrades" to MH.asType:
1042 * 1. interfaces are unchecked (that is, treated as if aliased to Object)
1043 * Therefore, {@code Object->CharSequence} is possible in both cases but has different semantics
1044 * 2. the full matrix of primitive-to-primitive conversions is supported
1045 * Narrowing like {@code long->byte} and basic-typing like {@code boolean->int}
1046 * are not supported by asType, but anything supported by asType is equivalent
1047 * with MHs.eCE.
1048 * 3a. unboxing conversions can be followed by the full matrix of primitive conversions
1049 * 3b. unboxing of null is permitted (creates a zero primitive value)
1050 * Other than interfaces, reference-to-reference conversions are the same.
1051 * Boxing primitives to references is the same for both operators.
1052 */
1053 private static boolean explicitCastEquivalentToAsType(Class<?> src, Class<?> dst) {
1054 if (src == dst || dst == Object.class || dst == void.class) return true;
1055 if (src.isPrimitive()) {
1056 // Could be a prim/prim conversion, where casting is a strict superset.
1057 // Or a boxing conversion, which is always to an exact wrapper class.
1058 return canConvert(src, dst);
1059 } else if (dst.isPrimitive()) {
1060 // Unboxing behavior is different between MHs.eCA & MH.asType (see 3b).
1061 return false;
1062 } else {
1063 // R->R always works, but we have to avoid a check-cast to an interface.
1064 return !dst.isInterface() || dst.isAssignableFrom(src);
1065 }
1066 }
1067
1068 private boolean canConvertParameters(Class<?>[] srcTypes, Class<?>[] dstTypes) {
1069 for (int i = 0; i < srcTypes.length; i++) {
1070 if (!canConvert(srcTypes[i], dstTypes[i])) {
1071 return false;
1072 }
1073 }
1074 return true;
1075 }
1076
1077 /*non-public*/
1078 static boolean canConvert(Class<?> src, Class<?> dst) {
1079 // short-circuit a few cases:
1080 if (src == dst || src == Object.class || dst == Object.class) return true;
1081 // the remainder of this logic is documented in MethodHandle.asType
1082 if (src.isPrimitive()) {
1083 // can force void to an explicit null, a la reflect.Method.invoke
1084 // can also force void to a primitive zero, by analogy
1085 if (src == void.class) return true; //or !dst.isPrimitive()?
1086 Wrapper sw = Wrapper.forPrimitiveType(src);
1087 if (dst.isPrimitive()) {
1088 // P->P must widen
1089 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw);
1090 } else {
1091 // P->R must box and widen
1092 return dst.isAssignableFrom(sw.wrapperType());
1093 }
1094 } else if (dst.isPrimitive()) {
1095 // any value can be dropped
1096 if (dst == void.class) return true;
1097 Wrapper dw = Wrapper.forPrimitiveType(dst);
1098 // R->P must be able to unbox (from a dynamically chosen type) and widen
1099 // For example:
1100 // Byte/Number/Comparable/Object -> dw:Byte -> byte.
1101 // Character/Comparable/Object -> dw:Character -> char
1102 // Boolean/Comparable/Object -> dw:Boolean -> boolean
1103 // This means that dw must be cast-compatible with src.
1104 if (src.isAssignableFrom(dw.wrapperType())) {
1105 return true;
1106 }
1107 // The above does not work if the source reference is strongly typed
1108 // to a wrapper whose primitive must be widened. For example:
1109 // Byte -> unbox:byte -> short/int/long/float/double
1110 // Character -> unbox:char -> int/long/float/double
1111 if (Wrapper.isWrapperType(src) &&
1112 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) {
1113 // can unbox from src and then widen to dst
1114 return true;
1115 }
1116 // We have already covered cases which arise due to runtime unboxing
1117 // of a reference type which covers several wrapper types:
1118 // Object -> cast:Integer -> unbox:int -> long/float/double
1119 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double
1120 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a
1121 // subclass of Number which wraps a value that can convert to char.
1122 // Since there is none, we don't need an extra check here to cover char or boolean.
1123 return false;
1124 } else {
1125 // R->R always works, since null is always valid dynamically
1126 return true;
1127 }
1128 }
1129
1130 //--- Queries which have to do with the bytecode architecture
1131
1132 /** Reports the number of JVM stack slots required to invoke a method
1133 * of this type. Note that (for historical reasons) the JVM requires
1134 * a second stack slot to pass long and double arguments.
1135 * So this method returns {@link #parameterCount() parameterCount} plus the
1136 * number of long and double parameters (if any).
1137 * <p>
1138 * This method is included for the benefit of applications that must
1139 * generate bytecodes that process method handles and invokedynamic.
1140 * @return the number of JVM stack slots for this type's parameters
1141 */
1142 /*non-public*/
1143 int parameterSlotCount() {
1144 return form.parameterSlotCount();
1145 }
1146
1147 /*non-public*/
1148 Invokers invokers() {
1149 Invokers inv = invokers;
1150 if (inv != null) return inv;
1151 invokers = inv = new Invokers(this);
1152 return inv;
1153 }
1154
1155 /**
1156 * Finds or creates an instance of a method type of the given method descriptor
1157 * (JVMS {@jvms 4.3.3}). This method is a convenience method for
1158 * {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
1159 * Any class or interface name embedded in the descriptor string will be
1160 * resolved by the given loader (or if it is {@code null}, on the system class loader).
1161 *
1162 * @apiNote
1163 * It is possible to encounter method types that have valid descriptors but
1164 * cannot be constructed by this method, because their component types are
1165 * not visible from a common class loader.
1166 * <p>
1167 * This method is included for the benefit of applications that must
1168 * generate bytecodes that process method handles and {@code invokedynamic}.
1169 * @param descriptor a method descriptor string
1170 * @param loader the class loader in which to look up the types
1171 * @return a method type of the given method descriptor
1172 * @throws NullPointerException if the string is {@code null}
1173 * @throws IllegalArgumentException if the string is not a method descriptor
1174 * @throws TypeNotPresentException if a named type cannot be found
1175 * @jvms 4.3.3 Method Descriptors
1176 */
1177 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader)
1178 throws IllegalArgumentException, TypeNotPresentException
1179 {
1180 return fromDescriptor(descriptor,
1181 (loader == null) ? ClassLoader.getSystemClassLoader() : loader);
1182 }
1183
1184 /**
1185 * Same as {@link #fromMethodDescriptorString(String, ClassLoader)}, but
1186 * {@code null} ClassLoader means the bootstrap loader is used here.
1187 * <p>
1188 * IMPORTANT: This method is preferable for JDK internal use as it more
1189 * correctly interprets {@code null} ClassLoader than
1190 * {@link #fromMethodDescriptorString(String, ClassLoader)}.
1191 * Use of this method also avoids early initialization issues when system
1192 * ClassLoader is not initialized yet.
1193 */
1194 static MethodType fromDescriptor(String descriptor, ClassLoader loader)
1195 throws IllegalArgumentException, TypeNotPresentException
1196 {
1197 if (!descriptor.startsWith("(") || // also generates NPE if needed
1198 descriptor.indexOf(')') < 0 ||
1199 descriptor.indexOf('.') >= 0)
1200 throw newIllegalArgumentException("not a method descriptor: "+descriptor);
1201 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader);
1202 Class<?> rtype = types.remove(types.size() - 1);
1203 Class<?>[] ptypes = listToArray(types);
1204 return methodType(rtype, ptypes, true);
1205 }
1206
1207 /**
1208 * {@return the descriptor string for this method type} This method
1209 * is equivalent to calling {@link #descriptorString() MethodType::descriptorString}.
1210 *
1211 * @apiNote
1212 * This is not a strict inverse of {@link #fromMethodDescriptorString
1213 * fromMethodDescriptorString} which requires a method type descriptor
1214 * (JVMS {@jvms 4.3.3}) and a suitable class loader argument.
1215 * Two distinct {@code MethodType} objects can have an identical
1216 * descriptor string as distinct classes can have the same name
1217 * but different class loaders.
1218 *
1219 * <p>
1220 * This method is included for the benefit of applications that must
1221 * generate bytecodes that process method handles and {@code invokedynamic}.
1222 * @jvms 4.3.3 Method Descriptors
1223 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
1224 */
1225 public String toMethodDescriptorString() {
1226 String desc = methodDescriptor;
1227 if (desc == null) {
1228 desc = BytecodeDescriptor.unparseMethod(this.rtype, this.ptypes);
1229 methodDescriptor = desc;
1230 }
1231 return desc;
1232 }
1233
1234 /**
1235 * {@return the descriptor string for this method type}
1236 *
1237 * <p>
1238 * If this method type can be {@linkplain ##descriptor described nominally},
1239 * then the result is a method type descriptor (JVMS {@jvms 4.3.3}).
1240 * {@link MethodTypeDesc MethodTypeDesc} for this method type
1241 * can be produced by calling {@link MethodTypeDesc#ofDescriptor(String)
1242 * MethodTypeDesc::ofDescriptor} with the result descriptor string.
1243 * <p>
1244 * If this method type cannot be {@linkplain ##descriptor described nominally}
1245 * and the result is a string of the form:
1246 * <blockquote>{@code "(<parameter-descriptors>)<return-descriptor>"}</blockquote>
1247 * where {@code <parameter-descriptors>} is the concatenation of the
1248 * {@linkplain Class#descriptorString() descriptor string} of all
1249 * of the parameter types and the {@linkplain Class#descriptorString() descriptor string}
1250 * of the return type. No {@link java.lang.constant.MethodTypeDesc MethodTypeDesc}
1251 * can be produced from the result string.
1252 *
1253 * @since 12
1254 * @jvms 4.3.3 Method Descriptors
1255 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
1256 */
1257 @Override
1258 public String descriptorString() {
1259 return toMethodDescriptorString();
1260 }
1261
1262 /*non-public*/
1263 static String toFieldDescriptorString(Class<?> cls) {
1264 return BytecodeDescriptor.unparse(cls);
1265 }
1266
1267 /**
1268 * Returns a nominal descriptor for this instance, if one can be
1269 * constructed, or an empty {@link Optional} if one cannot be.
1270 *
1271 * @return An {@link Optional} containing the resulting nominal descriptor,
1272 * or an empty {@link Optional} if one cannot be constructed.
1273 * @since 12
1274 * @see <a href="#descriptor">Nominal Descriptor for {@code MethodType}</a>
1275 */
1276 @Override
1277 public Optional<MethodTypeDesc> describeConstable() {
1278 var retDesc = returnType().describeConstable();
1279 if (retDesc.isEmpty())
1280 return Optional.empty();
1281
1282 if (parameterCount() == 0)
1283 return Optional.of(MethodTypeDesc.of(retDesc.get()));
1284
1285 var params = new ClassDesc[parameterCount()];
1286 for (int i = 0; i < params.length; i++) {
1287 var paramDesc = parameterType(i).describeConstable();
1288 if (paramDesc.isEmpty())
1289 return Optional.empty();
1290 params[i] = paramDesc.get();
1291 }
1292 return Optional.of(MethodTypeDesc.of(retDesc.get(), params));
1293 }
1294
1295 //--- Serialization.
1296
1297 /**
1298 * There are no serializable fields for {@code MethodType}.
1299 */
1300 @java.io.Serial
1301 private static final java.io.ObjectStreamField[] serialPersistentFields = { };
1302
1303 /**
1304 * Save the {@code MethodType} instance to a stream.
1305 *
1306 * @serialData
1307 * For portability, the serialized format does not refer to named fields.
1308 * Instead, the return type and parameter type arrays are written directly
1309 * from the {@code writeObject} method, using two calls to {@code s.writeObject}
1310 * as follows:
1311 * <blockquote><pre>{@code
1312 s.writeObject(this.returnType());
1313 s.writeObject(this.parameterArray());
1314 * }</pre></blockquote>
1315 * <p>
1316 * The deserialized field values are checked as if they were
1317 * provided to the factory method {@link #methodType(Class,Class[]) methodType}.
1318 * For example, null values, or {@code void} parameter types,
1319 * will lead to exceptions during deserialization.
1320 * @param s the stream to write the object to
1321 * @throws java.io.IOException if there is a problem writing the object
1322 */
1323 @java.io.Serial
1324 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
1325 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array
1326 s.writeObject(returnType());
1327 s.writeObject(parameterArray());
1328 }
1329
1330 /**
1331 * Reconstitute the {@code MethodType} instance from a stream (that is,
1332 * deserialize it).
1333 * This instance is a scratch object with bogus final fields.
1334 * It provides the parameters to the factory method called by
1335 * {@link #readResolve readResolve}.
1336 * After that call it is discarded.
1337 * @param s the stream to read the object from
1338 * @throws java.io.IOException if there is a problem reading the object
1339 * @throws ClassNotFoundException if one of the component classes cannot be resolved
1340 * @see #readResolve
1341 * @see #writeObject
1342 */
1343 @java.io.Serial
1344 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
1345 // Assign defaults in case this object escapes
1346 UNSAFE.putReference(this, OffsetHolder.rtypeOffset, void.class);
1347 UNSAFE.putReference(this, OffsetHolder.ptypesOffset, NO_PTYPES);
1348
1349 s.defaultReadObject(); // requires serialPersistentFields to be an empty array
1350
1351 Class<?> returnType = (Class<?>) s.readObject();
1352 Class<?>[] parameterArray = (Class<?>[]) s.readObject();
1353
1354 // Verify all operands, and make sure ptypes is unshared
1355 // Cache the new MethodType for readResolve
1356 wrapAlt = new MethodType[]{MethodType.methodType(returnType, parameterArray)};
1357 }
1358
1359 // Support for resetting final fields while deserializing. Implement Holder
1360 // pattern to make the rarely needed offset calculation lazy.
1361 private static class OffsetHolder {
1362 static final long rtypeOffset
1363 = UNSAFE.objectFieldOffset(MethodType.class, "rtype");
1364
1365 static final long ptypesOffset
1366 = UNSAFE.objectFieldOffset(MethodType.class, "ptypes");
1367 }
1368
1369 /**
1370 * Resolves and initializes a {@code MethodType} object
1371 * after serialization.
1372 * @return the fully initialized {@code MethodType} object
1373 */
1374 @java.io.Serial
1375 private Object readResolve() {
1376 // Do not use a trusted path for deserialization:
1377 // return makeImpl(rtype, ptypes, true);
1378 // Verify all operands, and make sure ptypes is unshared:
1379 // Return a new validated MethodType for the rtype and ptypes passed from readObject.
1380 MethodType mt = ((MethodType[])wrapAlt)[0];
1381 wrapAlt = null;
1382 return mt;
1383 }
1384 }