1 /*
2 * Copyright (c) 2008, 2017, 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 jdk.internal.vm.annotation.Stable;
29 import sun.invoke.util.Wrapper;
30 import java.lang.ref.WeakReference;
31 import java.lang.ref.Reference;
32 import java.lang.ref.ReferenceQueue;
33 import java.util.Arrays;
34 import java.util.Collections;
35 import java.util.List;
36 import java.util.Objects;
37 import java.util.StringJoiner;
38 import java.util.concurrent.ConcurrentMap;
39 import java.util.concurrent.ConcurrentHashMap;
40 import sun.invoke.util.BytecodeDescriptor;
41 import static java.lang.invoke.MethodHandleStatics.*;
42 import sun.invoke.util.VerifyType;
43
44 /**
45 * A method type represents the arguments and return type accepted and
46 * returned by a method handle, or the arguments and return type passed
47 * and expected by a method handle caller. Method types must be properly
48 * matched between a method handle and all its callers,
49 * and the JVM's operations enforce this matching at, specifically
50 * during calls to {@link MethodHandle#invokeExact MethodHandle.invokeExact}
51 * and {@link MethodHandle#invoke MethodHandle.invoke}, and during execution
52 * of {@code invokedynamic} instructions.
53 * <p>
54 * The structure is a return type accompanied by any number of parameter types.
55 * The types (primitive, {@code void}, and reference) are represented by {@link Class} objects.
56 * (For ease of exposition, we treat {@code void} as if it were a type.
57 * In fact, it denotes the absence of a return type.)
58 * <p>
59 * All instances of {@code MethodType} are immutable.
60 * Two instances are completely interchangeable if they compare equal.
61 * Equality depends on pairwise correspondence of the return and parameter types and on nothing else.
62 * <p>
63 * This type can be created only by factory methods.
64 * All factory methods may cache values, though caching is not guaranteed.
65 * Some factory methods are static, while others are virtual methods which
66 * modify precursor method types, e.g., by changing a selected parameter.
67 * <p>
68 * Factory methods which operate on groups of parameter types
69 * are systematically presented in two versions, so that both Java arrays and
70 * Java lists can be used to work with groups of parameter types.
71 * The query methods {@code parameterArray} and {@code parameterList}
72 * also provide a choice between arrays and lists.
73 * <p>
74 * {@code MethodType} objects are sometimes derived from bytecode instructions
75 * such as {@code invokedynamic}, specifically from the type descriptor strings associated
76 * with the instructions in a class file's constant pool.
77 * <p>
78 * Like classes and strings, method types can also be represented directly
79 * in a class file's constant pool as constants.
80 * A method type may be loaded by an {@code ldc} instruction which refers
81 * to a suitable {@code CONSTANT_MethodType} constant pool entry.
82 * The entry refers to a {@code CONSTANT_Utf8} spelling for the descriptor string.
83 * (For full details on method type constants,
84 * see sections 4.4.8 and 5.4.3.5 of the Java Virtual Machine Specification.)
85 * <p>
86 * When the JVM materializes a {@code MethodType} from a descriptor string,
87 * all classes named in the descriptor must be accessible, and will be loaded.
88 * (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.)
89 * This loading may occur at any time before the {@code MethodType} object is first derived.
90 * @author John Rose, JSR 292 EG
91 * @since 1.7
92 */
93 public final
94 class MethodType implements java.io.Serializable {
95 private static final long serialVersionUID = 292L; // {rtype, {ptype...}}
96
97 // The rtype and ptypes fields define the structural identity of the method type:
98 private final @Stable Class<?> rtype;
99 private final @Stable Class<?>[] ptypes;
100
101 // The remaining fields are caches of various sorts:
102 private @Stable MethodTypeForm form; // erased form, plus cached data about primitives
103 private @Stable MethodType wrapAlt; // alternative wrapped/unwrapped version
104 private @Stable Invokers invokers; // cache of handy higher-order adapters
105 private @Stable String methodDescriptor; // cache for toMethodDescriptorString
106
107 /**
108 * Constructor that performs no copying or validation.
109 * Should only be called from the factory method makeImpl
110 */
111 private MethodType(Class<?> rtype, Class<?>[] ptypes) {
112 this.rtype = rtype;
113 this.ptypes = ptypes;
114 }
115
116 /*trusted*/ MethodTypeForm form() { return form; }
117 /*trusted*/ Class<?> rtype() { return rtype; }
118 /*trusted*/ Class<?>[] ptypes() { return ptypes; }
119
120 void setForm(MethodTypeForm f) { form = f; }
121
122 /** This number, mandated by the JVM spec as 255,
123 * is the maximum number of <em>slots</em>
124 * that any Java method can receive in its argument list.
125 * It limits both JVM signatures and method type objects.
126 * The longest possible invocation will look like
127 * {@code staticMethod(arg1, arg2, ..., arg255)} or
128 * {@code x.virtualMethod(arg1, arg2, ..., arg254)}.
129 */
130 /*non-public*/ static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec.
131
132 /** This number is the maximum arity of a method handle, 254.
133 * It is derived from the absolute JVM-imposed arity by subtracting one,
134 * which is the slot occupied by the method handle itself at the
135 * beginning of the argument list used to invoke the method handle.
136 * The longest possible invocation will look like
137 * {@code mh.invoke(arg1, arg2, ..., arg254)}.
138 */
139 // Issue: Should we allow MH.invokeWithArguments to go to the full 255?
140 /*non-public*/ static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver
141
142 /** This number is the maximum arity of a method handle invoker, 253.
143 * It is derived from the absolute JVM-imposed arity by subtracting two,
144 * which are the slots occupied by invoke method handle, and the
145 * target method handle, which are both at the beginning of the argument
146 * list used to invoke the target method handle.
147 * The longest possible invocation will look like
148 * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}.
149 */
150 /*non-public*/ static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker
151
152 private static void checkRtype(Class<?> rtype) {
153 Objects.requireNonNull(rtype);
154 }
155 private static void checkPtype(Class<?> ptype) {
156 Objects.requireNonNull(ptype);
157 if (ptype == void.class)
158 throw newIllegalArgumentException("parameter type cannot be void");
159 }
160 /** Return number of extra slots (count of long/double args). */
161 private static int checkPtypes(Class<?>[] ptypes) {
162 int slots = 0;
163 for (Class<?> ptype : ptypes) {
164 checkPtype(ptype);
165 if (ptype == double.class || ptype == long.class) {
166 slots++;
167 }
168 }
169 checkSlotCount(ptypes.length + slots);
170 return slots;
171 }
172
173 static {
174 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work:
175 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0);
176 }
177 static void checkSlotCount(int count) {
178 if ((count & MAX_JVM_ARITY) != count)
179 throw newIllegalArgumentException("bad parameter count "+count);
180 }
181 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) {
182 if (num instanceof Integer) num = "bad index: "+num;
183 return new IndexOutOfBoundsException(num.toString());
184 }
185
186 static final ConcurrentWeakInternSet<MethodType> internTable = new ConcurrentWeakInternSet<>();
187
188 static final Class<?>[] NO_PTYPES = {};
189
190 /**
191 * Finds or creates an instance of the given method type.
192 * @param rtype the return type
193 * @param ptypes the parameter types
194 * @return a method type with the given components
195 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
196 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
197 */
198 public static
199 MethodType methodType(Class<?> rtype, Class<?>[] ptypes) {
200 return makeImpl(rtype, ptypes, false);
201 }
202
203 /**
204 * Finds or creates a method type with the given components.
205 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
206 * @param rtype the return type
207 * @param ptypes the parameter types
208 * @return a method type with the given components
209 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
210 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
211 */
212 public static
213 MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) {
214 boolean notrust = false; // random List impl. could return evil ptypes array
215 return makeImpl(rtype, listToArray(ptypes), notrust);
216 }
217
218 private static Class<?>[] listToArray(List<Class<?>> ptypes) {
219 // sanity check the size before the toArray call, since size might be huge
220 checkSlotCount(ptypes.size());
221 return ptypes.toArray(NO_PTYPES);
222 }
223
224 /**
225 * Finds or creates a method type with the given components.
226 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
227 * The leading parameter type is prepended to the remaining array.
228 * @param rtype the return type
229 * @param ptype0 the first parameter type
230 * @param ptypes the remaining parameter types
231 * @return a method type with the given components
232 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null
233 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class}
234 */
235 public static
236 MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) {
237 Class<?>[] ptypes1 = new Class<?>[1+ptypes.length];
238 ptypes1[0] = ptype0;
239 System.arraycopy(ptypes, 0, ptypes1, 1, ptypes.length);
240 return makeImpl(rtype, ptypes1, true);
241 }
242
243 /**
244 * Finds or creates a method type with the given components.
245 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
246 * The resulting method has no parameter types.
247 * @param rtype the return type
248 * @return a method type with the given return value
249 * @throws NullPointerException if {@code rtype} is null
250 */
251 public static
252 MethodType methodType(Class<?> rtype) {
253 return makeImpl(rtype, NO_PTYPES, true);
254 }
255
256 /**
257 * Finds or creates a method type with the given components.
258 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
259 * The resulting method has the single given parameter type.
260 * @param rtype the return type
261 * @param ptype0 the parameter type
262 * @return a method type with the given return value and parameter type
263 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null
264 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class}
265 */
266 public static
267 MethodType methodType(Class<?> rtype, Class<?> ptype0) {
268 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true);
269 }
270
271 /**
272 * Finds or creates a method type with the given components.
273 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
274 * The resulting method has the same parameter types as {@code ptypes},
275 * and the specified return type.
276 * @param rtype the return type
277 * @param ptypes the method type which supplies the parameter types
278 * @return a method type with the given components
279 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null
280 */
281 public static
282 MethodType methodType(Class<?> rtype, MethodType ptypes) {
283 return makeImpl(rtype, ptypes.ptypes, true);
284 }
285
286 /**
287 * Sole factory method to find or create an interned method type.
288 * @param rtype desired return type
289 * @param ptypes desired parameter types
290 * @param trusted whether the ptypes can be used without cloning
291 * @return the unique method type of the desired structure
292 */
293 /*trusted*/ static
294 MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
295 if (ptypes.length == 0) {
296 ptypes = NO_PTYPES; trusted = true;
297 }
298 MethodType primordialMT = new MethodType(rtype, ptypes);
299 MethodType mt = internTable.get(primordialMT);
300 if (mt != null)
301 return mt;
302
303 // promote the object to the Real Thing, and reprobe
304 MethodType.checkRtype(rtype);
305 if (trusted) {
306 MethodType.checkPtypes(ptypes);
307 mt = primordialMT;
308 } else {
309 // Make defensive copy then validate
310 ptypes = Arrays.copyOf(ptypes, ptypes.length);
311 MethodType.checkPtypes(ptypes);
312 mt = new MethodType(rtype, ptypes);
313 }
314 mt.form = MethodTypeForm.findForm(mt);
315 return internTable.add(mt);
316 }
317 private static final @Stable MethodType[] objectOnlyTypes = new MethodType[20];
318
319 /**
320 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array.
321 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
322 * All parameters and the return type will be {@code Object},
323 * except the final array parameter if any, which will be {@code Object[]}.
324 * @param objectArgCount number of parameters (excluding the final array parameter if any)
325 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]}
326 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments
327 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true)
328 * @see #genericMethodType(int)
329 */
330 public static
331 MethodType genericMethodType(int objectArgCount, boolean finalArray) {
332 MethodType mt;
333 checkSlotCount(objectArgCount);
334 int ivarargs = (!finalArray ? 0 : 1);
335 int ootIndex = objectArgCount*2 + ivarargs;
336 if (ootIndex < objectOnlyTypes.length) {
337 mt = objectOnlyTypes[ootIndex];
338 if (mt != null) return mt;
339 }
340 Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs];
341 Arrays.fill(ptypes, Object.class);
342 if (ivarargs != 0) ptypes[objectArgCount] = Object[].class;
343 mt = makeImpl(Object.class, ptypes, true);
344 if (ootIndex < objectOnlyTypes.length) {
345 objectOnlyTypes[ootIndex] = mt; // cache it here also!
346 }
347 return mt;
348 }
349
350 /**
351 * Finds or creates a method type whose components are all {@code Object}.
352 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
353 * All parameters and the return type will be Object.
354 * @param objectArgCount number of parameters
355 * @return a generally applicable method type, for all calls of the given argument count
356 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255
357 * @see #genericMethodType(int, boolean)
358 */
359 public static
360 MethodType genericMethodType(int objectArgCount) {
361 return genericMethodType(objectArgCount, false);
362 }
363
364 /**
365 * Finds or creates a method type with a single different parameter type.
366 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
367 * @param num the index (zero-based) of the parameter type to change
368 * @param nptype a new parameter type to replace the old one with
369 * @return the same type, except with the selected parameter changed
370 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
371 * @throws IllegalArgumentException if {@code nptype} is {@code void.class}
372 * @throws NullPointerException if {@code nptype} is null
373 */
374 public MethodType changeParameterType(int num, Class<?> nptype) {
375 if (parameterType(num) == nptype) return this;
376 checkPtype(nptype);
377 Class<?>[] nptypes = ptypes.clone();
378 nptypes[num] = nptype;
379 return makeImpl(rtype, nptypes, true);
380 }
381
382 /**
383 * Finds or creates a method type with additional parameter types.
384 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
385 * @param num the position (zero-based) of the inserted parameter type(s)
386 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
387 * @return the same type, except with the selected parameter(s) inserted
388 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
389 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
390 * or if the resulting method type would have more than 255 parameter slots
391 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
392 */
393 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) {
394 int len = ptypes.length;
395 if (num < 0 || num > len)
396 throw newIndexOutOfBoundsException(num);
397 int ins = checkPtypes(ptypesToInsert);
398 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins);
399 int ilen = ptypesToInsert.length;
400 if (ilen == 0) return this;
401 Class<?>[] nptypes = new Class<?>[len + ilen];
402 if (num > 0) {
403 System.arraycopy(ptypes, 0, nptypes, 0, num);
404 }
405 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen);
406 if (num < len) {
407 System.arraycopy(ptypes, num, nptypes, num+ilen, len-num);
408 }
409 return makeImpl(rtype, nptypes, true);
410 }
411
412 /**
413 * Finds or creates a method type with additional parameter types.
414 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
415 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
416 * @return the same type, except with the selected parameter(s) appended
417 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
418 * or if the resulting method type would have more than 255 parameter slots
419 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
420 */
421 public MethodType appendParameterTypes(Class<?>... ptypesToInsert) {
422 return insertParameterTypes(parameterCount(), ptypesToInsert);
423 }
424
425 /**
426 * Finds or creates a method type with additional parameter types.
427 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
428 * @param num the position (zero-based) of the inserted parameter type(s)
429 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
430 * @return the same type, except with the selected parameter(s) inserted
431 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
432 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
433 * or if the resulting method type would have more than 255 parameter slots
434 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
435 */
436 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) {
437 return insertParameterTypes(num, listToArray(ptypesToInsert));
438 }
439
440 /**
441 * Finds or creates a method type with additional parameter types.
442 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
443 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
444 * @return the same type, except with the selected parameter(s) appended
445 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
446 * or if the resulting method type would have more than 255 parameter slots
447 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
448 */
449 public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) {
450 return insertParameterTypes(parameterCount(), ptypesToInsert);
451 }
452
453 /**
454 * Finds or creates a method type with modified parameter types.
455 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
456 * @param start the position (zero-based) of the first replaced parameter type(s)
457 * @param end the position (zero-based) after the last replaced parameter type(s)
458 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
459 * @return the same type, except with the selected parameter(s) replaced
460 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
461 * or if {@code end} is negative or greater than {@code parameterCount()}
462 * or if {@code start} is greater than {@code end}
463 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
464 * or if the resulting method type would have more than 255 parameter slots
465 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
466 */
467 /*non-public*/ MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) {
468 if (start == end)
469 return insertParameterTypes(start, ptypesToInsert);
470 int len = ptypes.length;
471 if (!(0 <= start && start <= end && end <= len))
472 throw newIndexOutOfBoundsException("start="+start+" end="+end);
473 int ilen = ptypesToInsert.length;
474 if (ilen == 0)
475 return dropParameterTypes(start, end);
476 return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert);
477 }
478
479 /** Replace the last arrayLength parameter types with the component type of arrayType.
480 * @param arrayType any array type
481 * @param pos position at which to spread
482 * @param arrayLength the number of parameter types to change
483 * @return the resulting type
484 */
485 /*non-public*/ MethodType asSpreaderType(Class<?> arrayType, int pos, int arrayLength) {
486 assert(parameterCount() >= arrayLength);
487 int spreadPos = pos;
488 if (arrayLength == 0) return this; // nothing to change
489 if (arrayType == Object[].class) {
490 if (isGeneric()) return this; // nothing to change
491 if (spreadPos == 0) {
492 // no leading arguments to preserve; go generic
493 MethodType res = genericMethodType(arrayLength);
494 if (rtype != Object.class) {
495 res = res.changeReturnType(rtype);
496 }
497 return res;
498 }
499 }
500 Class<?> elemType = arrayType.getComponentType();
501 assert(elemType != null);
502 for (int i = spreadPos; i < spreadPos + arrayLength; i++) {
503 if (ptypes[i] != elemType) {
504 Class<?>[] fixedPtypes = ptypes.clone();
505 Arrays.fill(fixedPtypes, i, spreadPos + arrayLength, elemType);
506 return methodType(rtype, fixedPtypes);
507 }
508 }
509 return this; // arguments check out; no change
510 }
511
512 /** Return the leading parameter type, which must exist and be a reference.
513 * @return the leading parameter type, after error checks
514 */
515 /*non-public*/ Class<?> leadingReferenceParameter() {
516 Class<?> ptype;
517 if (ptypes.length == 0 ||
518 (ptype = ptypes[0]).isPrimitive())
519 throw newIllegalArgumentException("no leading reference parameter");
520 return ptype;
521 }
522
523 /** Delete the last parameter type and replace it with arrayLength copies of the component type of arrayType.
524 * @param arrayType any array type
525 * @param pos position at which to insert parameters
526 * @param arrayLength the number of parameter types to insert
527 * @return the resulting type
528 */
529 /*non-public*/ MethodType asCollectorType(Class<?> arrayType, int pos, int arrayLength) {
530 assert(parameterCount() >= 1);
531 assert(pos < ptypes.length);
532 assert(ptypes[pos].isAssignableFrom(arrayType));
533 MethodType res;
534 if (arrayType == Object[].class) {
535 res = genericMethodType(arrayLength);
536 if (rtype != Object.class) {
537 res = res.changeReturnType(rtype);
538 }
539 } else {
540 Class<?> elemType = arrayType.getComponentType();
541 assert(elemType != null);
542 res = methodType(rtype, Collections.nCopies(arrayLength, elemType));
543 }
544 if (ptypes.length == 1) {
545 return res;
546 } else {
547 // insert after (if need be), then before
548 if (pos < ptypes.length - 1) {
549 res = res.insertParameterTypes(arrayLength, Arrays.copyOfRange(ptypes, pos + 1, ptypes.length));
550 }
551 return res.insertParameterTypes(0, Arrays.copyOf(ptypes, pos));
552 }
553 }
554
555 /**
556 * Finds or creates a method type with some parameter types omitted.
557 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
558 * @param start the index (zero-based) of the first parameter type to remove
559 * @param end the index (greater than {@code start}) of the first parameter type after not to remove
560 * @return the same type, except with the selected parameter(s) removed
561 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
562 * or if {@code end} is negative or greater than {@code parameterCount()}
563 * or if {@code start} is greater than {@code end}
564 */
565 public MethodType dropParameterTypes(int start, int end) {
566 int len = ptypes.length;
567 if (!(0 <= start && start <= end && end <= len))
568 throw newIndexOutOfBoundsException("start="+start+" end="+end);
569 if (start == end) return this;
570 Class<?>[] nptypes;
571 if (start == 0) {
572 if (end == len) {
573 // drop all parameters
574 nptypes = NO_PTYPES;
575 } else {
576 // drop initial parameter(s)
577 nptypes = Arrays.copyOfRange(ptypes, end, len);
578 }
579 } else {
580 if (end == len) {
581 // drop trailing parameter(s)
582 nptypes = Arrays.copyOfRange(ptypes, 0, start);
583 } else {
584 int tail = len - end;
585 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail);
586 System.arraycopy(ptypes, end, nptypes, start, tail);
587 }
588 }
589 return makeImpl(rtype, nptypes, true);
590 }
591
592 /**
593 * Finds or creates a method type with a different return type.
594 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
595 * @param nrtype a return parameter type to replace the old one with
596 * @return the same type, except with the return type change
597 * @throws NullPointerException if {@code nrtype} is null
598 */
599 public MethodType changeReturnType(Class<?> nrtype) {
600 if (returnType() == nrtype) return this;
601 return makeImpl(nrtype, ptypes, true);
602 }
603
604 /**
605 * Reports if this type contains a primitive argument or return value.
606 * The return type {@code void} counts as a primitive.
607 * @return true if any of the types are primitives
608 */
609 public boolean hasPrimitives() {
610 return form.hasPrimitives();
611 }
612
613 /**
614 * Reports if this type contains a wrapper argument or return value.
615 * Wrappers are types which box primitive values, such as {@link Integer}.
616 * The reference type {@code java.lang.Void} counts as a wrapper,
617 * if it occurs as a return type.
618 * @return true if any of the types are wrappers
619 */
620 public boolean hasWrappers() {
621 return unwrap() != this;
622 }
623
624 /**
625 * Erases all reference types to {@code Object}.
626 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
627 * All primitive types (including {@code void}) will remain unchanged.
628 * @return a version of the original type with all reference types replaced
629 */
630 public MethodType erase() {
631 return form.erasedType();
632 }
633
634 /**
635 * Erases all reference types to {@code Object}, and all subword types to {@code int}.
636 * This is the reduced type polymorphism used by private methods
637 * such as {@link MethodHandle#invokeBasic invokeBasic}.
638 * @return a version of the original type with all reference and subword types replaced
639 */
640 /*non-public*/ MethodType basicType() {
641 return form.basicType();
642 }
643
644 private static final @Stable Class<?>[] METHOD_HANDLE_ARRAY
645 = new Class<?>[] { MethodHandle.class };
646
647 /**
648 * @return a version of the original type with MethodHandle prepended as the first argument
649 */
650 /*non-public*/ MethodType invokerType() {
651 return insertParameterTypes(0, METHOD_HANDLE_ARRAY);
652 }
653
654 /**
655 * Converts all types, both reference and primitive, to {@code Object}.
656 * Convenience method for {@link #genericMethodType(int) genericMethodType}.
657 * The expression {@code type.wrap().erase()} produces the same value
658 * as {@code type.generic()}.
659 * @return a version of the original type with all types replaced
660 */
661 public MethodType generic() {
662 return genericMethodType(parameterCount());
663 }
664
665 /*non-public*/ boolean isGeneric() {
666 return this == erase() && !hasPrimitives();
667 }
668
669 /**
670 * Converts all primitive types to their corresponding wrapper types.
671 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
672 * All reference types (including wrapper types) will remain unchanged.
673 * A {@code void} return type is changed to the type {@code java.lang.Void}.
674 * The expression {@code type.wrap().erase()} produces the same value
675 * as {@code type.generic()}.
676 * @return a version of the original type with all primitive types replaced
677 */
678 public MethodType wrap() {
679 return hasPrimitives() ? wrapWithPrims(this) : this;
680 }
681
682 /**
683 * Converts all wrapper types to their corresponding primitive types.
684 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
685 * All primitive types (including {@code void}) will remain unchanged.
686 * A return type of {@code java.lang.Void} is changed to {@code void}.
687 * @return a version of the original type with all wrapper types replaced
688 */
689 public MethodType unwrap() {
690 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this);
691 return unwrapWithNoPrims(noprims);
692 }
693
694 private static MethodType wrapWithPrims(MethodType pt) {
695 assert(pt.hasPrimitives());
696 MethodType wt = pt.wrapAlt;
697 if (wt == null) {
698 // fill in lazily
699 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP, MethodTypeForm.WRAP);
700 assert(wt != null);
701 pt.wrapAlt = wt;
702 }
703 return wt;
704 }
705
706 private static MethodType unwrapWithNoPrims(MethodType wt) {
707 assert(!wt.hasPrimitives());
708 MethodType uwt = wt.wrapAlt;
709 if (uwt == null) {
710 // fill in lazily
711 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP, MethodTypeForm.UNWRAP);
712 if (uwt == null)
713 uwt = wt; // type has no wrappers or prims at all
714 wt.wrapAlt = uwt;
715 }
716 return uwt;
717 }
718
719 /**
720 * Returns the parameter type at the specified index, within this method type.
721 * @param num the index (zero-based) of the desired parameter type
722 * @return the selected parameter type
723 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
724 */
725 public Class<?> parameterType(int num) {
726 return ptypes[num];
727 }
728 /**
729 * Returns the number of parameter types in this method type.
730 * @return the number of parameter types
731 */
732 public int parameterCount() {
733 return ptypes.length;
734 }
735 /**
736 * Returns the return type of this method type.
737 * @return the return type
738 */
739 public Class<?> returnType() {
740 return rtype;
741 }
742
743 /**
744 * Presents the parameter types as a list (a convenience method).
745 * The list will be immutable.
746 * @return the parameter types (as an immutable list)
747 */
748 public List<Class<?>> parameterList() {
749 return Collections.unmodifiableList(Arrays.asList(ptypes.clone()));
750 }
751
752 /**
753 * Returns the last parameter type of this method type.
754 * If this type has no parameters, the sentinel value
755 * {@code void.class} is returned instead.
756 * @apiNote
757 * <p>
758 * The sentinel value is chosen so that reflective queries can be
759 * made directly against the result value.
760 * The sentinel value cannot be confused with a real parameter,
761 * since {@code void} is never acceptable as a parameter type.
762 * For variable arity invocation modes, the expression
763 * {@link Class#getComponentType lastParameterType().getComponentType()}
764 * is useful to query the type of the "varargs" parameter.
765 * @return the last parameter type if any, else {@code void.class}
766 * @since 10
767 */
768 public Class<?> lastParameterType() {
769 int len = ptypes.length;
770 return len == 0 ? void.class : ptypes[len-1];
771 }
772
773 /**
774 * Presents the parameter types as an array (a convenience method).
775 * Changes to the array will not result in changes to the type.
776 * @return the parameter types (as a fresh copy if necessary)
777 */
778 public Class<?>[] parameterArray() {
779 return ptypes.clone();
780 }
781
782 /**
783 * Compares the specified object with this type for equality.
784 * That is, it returns {@code true} if and only if the specified object
785 * is also a method type with exactly the same parameters and return type.
786 * @param x object to compare
787 * @see Object#equals(Object)
788 */
789 @Override
790 public boolean equals(Object x) {
791 return this == x || x instanceof MethodType && equals((MethodType)x);
792 }
793
794 private boolean equals(MethodType that) {
795 return this.rtype == that.rtype
796 && Arrays.equals(this.ptypes, that.ptypes);
797 }
798
799 /**
800 * Returns the hash code value for this method type.
801 * It is defined to be the same as the hashcode of a List
802 * whose elements are the return type followed by the
803 * parameter types.
804 * @return the hash code value for this method type
805 * @see Object#hashCode()
806 * @see #equals(Object)
807 * @see List#hashCode()
808 */
809 @Override
810 public int hashCode() {
811 int hashCode = 31 + rtype.hashCode();
812 for (Class<?> ptype : ptypes)
813 hashCode = 31*hashCode + ptype.hashCode();
814 return hashCode;
815 }
816
817 /**
818 * Returns a string representation of the method type,
819 * of the form {@code "(PT0,PT1...)RT"}.
820 * The string representation of a method type is a
821 * parenthesis enclosed, comma separated list of type names,
822 * followed immediately by the return type.
823 * <p>
824 * Each type is represented by its
825 * {@link java.lang.Class#getSimpleName simple name}.
826 */
827 @Override
828 public String toString() {
829 StringJoiner sj = new StringJoiner(",", "(",
830 ")" + rtype.getSimpleName());
831 for (int i = 0; i < ptypes.length; i++) {
832 sj.add(ptypes[i].getSimpleName());
833 }
834 return sj.toString();
835 }
836
837 /** True if my parameter list is effectively identical to the given full list,
838 * after skipping the given number of my own initial parameters.
839 * In other words, after disregarding {@code skipPos} parameters,
840 * my remaining parameter list is no longer than the {@code fullList}, and
841 * is equal to the same-length initial sublist of {@code fullList}.
842 */
843 /*non-public*/
844 boolean effectivelyIdenticalParameters(int skipPos, List<Class<?>> fullList) {
845 int myLen = ptypes.length, fullLen = fullList.size();
846 if (skipPos > myLen || myLen - skipPos > fullLen)
847 return false;
848 List<Class<?>> myList = Arrays.asList(ptypes);
849 if (skipPos != 0) {
850 myList = myList.subList(skipPos, myLen);
851 myLen -= skipPos;
852 }
853 if (fullLen == myLen)
854 return myList.equals(fullList);
855 else
856 return myList.equals(fullList.subList(0, myLen));
857 }
858
859 /** True if the old return type can always be viewed (w/o casting) under new return type,
860 * and the new parameters can be viewed (w/o casting) under the old parameter types.
861 */
862 /*non-public*/
863 boolean isViewableAs(MethodType newType, boolean keepInterfaces) {
864 if (!VerifyType.isNullConversion(returnType(), newType.returnType(), keepInterfaces))
865 return false;
866 if (form == newType.form && form.erasedType == this)
867 return true; // my reference parameters are all Object
868 if (ptypes == newType.ptypes)
869 return true;
870 int argc = parameterCount();
871 if (argc != newType.parameterCount())
872 return false;
873 for (int i = 0; i < argc; i++) {
874 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i), keepInterfaces))
875 return false;
876 }
877 return true;
878 }
879 /*non-public*/
880 boolean isConvertibleTo(MethodType newType) {
881 MethodTypeForm oldForm = this.form();
882 MethodTypeForm newForm = newType.form();
883 if (oldForm == newForm)
884 // same parameter count, same primitive/object mix
885 return true;
886 if (!canConvert(returnType(), newType.returnType()))
887 return false;
888 Class<?>[] srcTypes = newType.ptypes;
889 Class<?>[] dstTypes = ptypes;
890 if (srcTypes == dstTypes)
891 return true;
892 int argc;
893 if ((argc = srcTypes.length) != dstTypes.length)
894 return false;
895 if (argc <= 1) {
896 if (argc == 1 && !canConvert(srcTypes[0], dstTypes[0]))
897 return false;
898 return true;
899 }
900 if ((oldForm.primitiveParameterCount() == 0 && oldForm.erasedType == this) ||
901 (newForm.primitiveParameterCount() == 0 && newForm.erasedType == newType)) {
902 // Somewhat complicated test to avoid a loop of 2 or more trips.
903 // If either type has only Object parameters, we know we can convert.
904 assert(canConvertParameters(srcTypes, dstTypes));
905 return true;
906 }
907 return canConvertParameters(srcTypes, dstTypes);
908 }
909
910 /** Returns true if MHs.explicitCastArguments produces the same result as MH.asType.
911 * If the type conversion is impossible for either, the result should be false.
912 */
913 /*non-public*/
914 boolean explicitCastEquivalentToAsType(MethodType newType) {
915 if (this == newType) return true;
916 if (!explicitCastEquivalentToAsType(rtype, newType.rtype)) {
917 return false;
918 }
919 Class<?>[] srcTypes = newType.ptypes;
920 Class<?>[] dstTypes = ptypes;
921 if (dstTypes == srcTypes) {
922 return true;
923 }
924 assert(dstTypes.length == srcTypes.length);
925 for (int i = 0; i < dstTypes.length; i++) {
926 if (!explicitCastEquivalentToAsType(srcTypes[i], dstTypes[i])) {
927 return false;
928 }
929 }
930 return true;
931 }
932
933 /** Reports true if the src can be converted to the dst, by both asType and MHs.eCE,
934 * and with the same effect.
935 * MHs.eCA has the following "upgrades" to MH.asType:
936 * 1. interfaces are unchecked (that is, treated as if aliased to Object)
937 * Therefore, {@code Object->CharSequence} is possible in both cases but has different semantics
938 * 2. the full matrix of primitive-to-primitive conversions is supported
939 * Narrowing like {@code long->byte} and basic-typing like {@code boolean->int}
940 * are not supported by asType, but anything supported by asType is equivalent
941 * with MHs.eCE.
942 * 3a. unboxing conversions can be followed by the full matrix of primitive conversions
943 * 3b. unboxing of null is permitted (creates a zero primitive value)
944 * Other than interfaces, reference-to-reference conversions are the same.
945 * Boxing primitives to references is the same for both operators.
946 */
947 private static boolean explicitCastEquivalentToAsType(Class<?> src, Class<?> dst) {
948 if (src == dst || dst == Object.class || dst == void.class) return true;
949 if (src.isPrimitive()) {
950 // Could be a prim/prim conversion, where casting is a strict superset.
951 // Or a boxing conversion, which is always to an exact wrapper class.
952 return canConvert(src, dst);
953 } else if (dst.isPrimitive()) {
954 // Unboxing behavior is different between MHs.eCA & MH.asType (see 3b).
955 return false;
956 } else {
957 // R->R always works, but we have to avoid a check-cast to an interface.
958 return !dst.isInterface() || dst.isAssignableFrom(src);
959 }
960 }
961
962 private boolean canConvertParameters(Class<?>[] srcTypes, Class<?>[] dstTypes) {
963 for (int i = 0; i < srcTypes.length; i++) {
964 if (!canConvert(srcTypes[i], dstTypes[i])) {
965 return false;
966 }
967 }
968 return true;
969 }
970
971 /*non-public*/
972 static boolean canConvert(Class<?> src, Class<?> dst) {
973 // short-circuit a few cases:
974 if (src == dst || src == Object.class || dst == Object.class) return true;
975 // the remainder of this logic is documented in MethodHandle.asType
976 if (src.isPrimitive()) {
977 // can force void to an explicit null, a la reflect.Method.invoke
978 // can also force void to a primitive zero, by analogy
979 if (src == void.class) return true; //or !dst.isPrimitive()?
980 Wrapper sw = Wrapper.forPrimitiveType(src);
981 if (dst.isPrimitive()) {
982 // P->P must widen
983 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw);
984 } else {
985 // P->R must box and widen
986 return dst.isAssignableFrom(sw.wrapperType());
987 }
988 } else if (dst.isPrimitive()) {
989 // any value can be dropped
990 if (dst == void.class) return true;
991 Wrapper dw = Wrapper.forPrimitiveType(dst);
992 // R->P must be able to unbox (from a dynamically chosen type) and widen
993 // For example:
994 // Byte/Number/Comparable/Object -> dw:Byte -> byte.
995 // Character/Comparable/Object -> dw:Character -> char
996 // Boolean/Comparable/Object -> dw:Boolean -> boolean
997 // This means that dw must be cast-compatible with src.
998 if (src.isAssignableFrom(dw.wrapperType())) {
999 return true;
1000 }
1001 // The above does not work if the source reference is strongly typed
1002 // to a wrapper whose primitive must be widened. For example:
1003 // Byte -> unbox:byte -> short/int/long/float/double
1004 // Character -> unbox:char -> int/long/float/double
1005 if (Wrapper.isWrapperType(src) &&
1006 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) {
1007 // can unbox from src and then widen to dst
1008 return true;
1009 }
1010 // We have already covered cases which arise due to runtime unboxing
1011 // of a reference type which covers several wrapper types:
1012 // Object -> cast:Integer -> unbox:int -> long/float/double
1013 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double
1014 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a
1015 // subclass of Number which wraps a value that can convert to char.
1016 // Since there is none, we don't need an extra check here to cover char or boolean.
1017 return false;
1018 } else {
1019 // R->R always works, since null is always valid dynamically
1020 return true;
1021 }
1022 }
1023
1024 /// Queries which have to do with the bytecode architecture
1025
1026 /** Reports the number of JVM stack slots required to invoke a method
1027 * of this type. Note that (for historical reasons) the JVM requires
1028 * a second stack slot to pass long and double arguments.
1029 * So this method returns {@link #parameterCount() parameterCount} plus the
1030 * number of long and double parameters (if any).
1031 * <p>
1032 * This method is included for the benefit of applications that must
1033 * generate bytecodes that process method handles and invokedynamic.
1034 * @return the number of JVM stack slots for this type's parameters
1035 */
1036 /*non-public*/ int parameterSlotCount() {
1037 return form.parameterSlotCount();
1038 }
1039
1040 /*non-public*/ Invokers invokers() {
1041 Invokers inv = invokers;
1042 if (inv != null) return inv;
1043 invokers = inv = new Invokers(this);
1044 return inv;
1045 }
1046
1047 /** Reports the number of JVM stack slots which carry all parameters including and after
1048 * the given position, which must be in the range of 0 to
1049 * {@code parameterCount} inclusive. Successive parameters are
1050 * more shallowly stacked, and parameters are indexed in the bytecodes
1051 * according to their trailing edge. Thus, to obtain the depth
1052 * in the outgoing call stack of parameter {@code N}, obtain
1053 * the {@code parameterSlotDepth} of its trailing edge
1054 * at position {@code N+1}.
1055 * <p>
1056 * Parameters of type {@code long} and {@code double} occupy
1057 * two stack slots (for historical reasons) and all others occupy one.
1058 * Therefore, the number returned is the number of arguments
1059 * <em>including</em> and <em>after</em> the given parameter,
1060 * <em>plus</em> the number of long or double arguments
1061 * at or after the argument for the given parameter.
1062 * <p>
1063 * This method is included for the benefit of applications that must
1064 * generate bytecodes that process method handles and invokedynamic.
1065 * @param num an index (zero-based, inclusive) within the parameter types
1066 * @return the index of the (shallowest) JVM stack slot transmitting the
1067 * given parameter
1068 * @throws IllegalArgumentException if {@code num} is negative or greater than {@code parameterCount()}
1069 */
1070 /*non-public*/ int parameterSlotDepth(int num) {
1071 if (num < 0 || num > ptypes.length)
1072 parameterType(num); // force a range check
1073 return form.parameterToArgSlot(num-1);
1074 }
1075
1076 /** Reports the number of JVM stack slots required to receive a return value
1077 * from a method of this type.
1078 * If the {@link #returnType() return type} is void, it will be zero,
1079 * else if the return type is long or double, it will be two, else one.
1080 * <p>
1081 * This method is included for the benefit of applications that must
1082 * generate bytecodes that process method handles and invokedynamic.
1083 * @return the number of JVM stack slots (0, 1, or 2) for this type's return value
1084 * Will be removed for PFD.
1085 */
1086 /*non-public*/ int returnSlotCount() {
1087 return form.returnSlotCount();
1088 }
1089
1090 /**
1091 * Finds or creates an instance of a method type, given the spelling of its bytecode descriptor.
1092 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
1093 * Any class or interface name embedded in the descriptor string
1094 * will be resolved by calling {@link ClassLoader#loadClass(java.lang.String)}
1095 * on the given loader (or if it is null, on the system class loader).
1096 * <p>
1097 * Note that it is possible to encounter method types which cannot be
1098 * constructed by this method, because their component types are
1099 * not all reachable from a common class loader.
1100 * <p>
1101 * This method is included for the benefit of applications that must
1102 * generate bytecodes that process method handles and {@code invokedynamic}.
1103 * @param descriptor a bytecode-level type descriptor string "(T...)T"
1104 * @param loader the class loader in which to look up the types
1105 * @return a method type matching the bytecode-level type descriptor
1106 * @throws NullPointerException if the string is null
1107 * @throws IllegalArgumentException if the string is not well-formed
1108 * @throws TypeNotPresentException if a named type cannot be found
1109 */
1110 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader)
1111 throws IllegalArgumentException, TypeNotPresentException
1112 {
1113 return fromDescriptor(descriptor,
1114 (loader == null) ? ClassLoader.getSystemClassLoader() : loader);
1115 }
1116
1117 /**
1118 * Same as {@link #fromMethodDescriptorString(String, ClassLoader)}, but
1119 * {@code null} ClassLoader means the bootstrap loader is used here.
1120 * <p>
1121 * IMPORTANT: This method is preferable for JDK internal use as it more
1122 * correctly interprets {@code null} ClassLoader than
1123 * {@link #fromMethodDescriptorString(String, ClassLoader)}.
1124 * Use of this method also avoids early initialization issues when system
1125 * ClassLoader is not initialized yet.
1126 */
1127 static MethodType fromDescriptor(String descriptor, ClassLoader loader)
1128 throws IllegalArgumentException, TypeNotPresentException
1129 {
1130 if (!descriptor.startsWith("(") || // also generates NPE if needed
1131 descriptor.indexOf(')') < 0 ||
1132 descriptor.indexOf('.') >= 0)
1133 throw newIllegalArgumentException("not a method descriptor: "+descriptor);
1134 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader);
1135 Class<?> rtype = types.remove(types.size() - 1);
1136 Class<?>[] ptypes = listToArray(types);
1137 return makeImpl(rtype, ptypes, true);
1138 }
1139
1140 /**
1141 * Produces a bytecode descriptor representation of the method type.
1142 * <p>
1143 * Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}.
1144 * Two distinct classes which share a common name but have different class loaders
1145 * will appear identical when viewed within descriptor strings.
1146 * <p>
1147 * This method is included for the benefit of applications that must
1148 * generate bytecodes that process method handles and {@code invokedynamic}.
1149 * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString},
1150 * because the latter requires a suitable class loader argument.
1151 * @return the bytecode type descriptor representation
1152 */
1153 public String toMethodDescriptorString() {
1154 String desc = methodDescriptor;
1155 if (desc == null) {
1156 desc = BytecodeDescriptor.unparseMethod(this.rtype, this.ptypes);
1157 methodDescriptor = desc;
1158 }
1159 return desc;
1160 }
1161
1162 /*non-public*/ static String toFieldDescriptorString(Class<?> cls) {
1163 return BytecodeDescriptor.unparse(cls);
1164 }
1165
1166 /// Serialization.
1167
1168 /**
1169 * There are no serializable fields for {@code MethodType}.
1170 */
1171 private static final java.io.ObjectStreamField[] serialPersistentFields = { };
1172
1173 /**
1174 * Save the {@code MethodType} instance to a stream.
1175 *
1176 * @serialData
1177 * For portability, the serialized format does not refer to named fields.
1178 * Instead, the return type and parameter type arrays are written directly
1179 * from the {@code writeObject} method, using two calls to {@code s.writeObject}
1180 * as follows:
1181 * <blockquote><pre>{@code
1182 s.writeObject(this.returnType());
1183 s.writeObject(this.parameterArray());
1184 * }</pre></blockquote>
1185 * <p>
1186 * The deserialized field values are checked as if they were
1187 * provided to the factory method {@link #methodType(Class,Class[]) methodType}.
1188 * For example, null values, or {@code void} parameter types,
1189 * will lead to exceptions during deserialization.
1190 * @param s the stream to write the object to
1191 * @throws java.io.IOException if there is a problem writing the object
1192 */
1193 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
1194 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array
1195 s.writeObject(returnType());
1196 s.writeObject(parameterArray());
1197 }
1198
1199 /**
1200 * Reconstitute the {@code MethodType} instance from a stream (that is,
1201 * deserialize it).
1202 * This instance is a scratch object with bogus final fields.
1203 * It provides the parameters to the factory method called by
1204 * {@link #readResolve readResolve}.
1205 * After that call it is discarded.
1206 * @param s the stream to read the object from
1207 * @throws java.io.IOException if there is a problem reading the object
1208 * @throws ClassNotFoundException if one of the component classes cannot be resolved
1209 * @see #readResolve
1210 * @see #writeObject
1211 */
1212 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
1213 // Assign temporary defaults in case this object escapes
1214 MethodType_init(void.class, NO_PTYPES);
1215
1216 s.defaultReadObject(); // requires serialPersistentFields to be an empty array
1217
1218 Class<?> returnType = (Class<?>) s.readObject();
1219 Class<?>[] parameterArray = (Class<?>[]) s.readObject();
1220 parameterArray = parameterArray.clone(); // make sure it is unshared
1221
1222 // Assign deserialized values
1223 MethodType_init(returnType, parameterArray);
1224 }
1225
1226 // Initialization of state for deserialization only
1227 private void MethodType_init(Class<?> rtype, Class<?>[] ptypes) {
1228 // In order to communicate these values to readResolve, we must
1229 // store them into the implementation-specific final fields.
1230 checkRtype(rtype);
1231 checkPtypes(ptypes);
1232 UNSAFE.putObject(this, OffsetHolder.rtypeOffset, rtype);
1233 UNSAFE.putObject(this, OffsetHolder.ptypesOffset, ptypes);
1234 }
1235
1236 // Support for resetting final fields while deserializing. Implement Holder
1237 // pattern to make the rarely needed offset calculation lazy.
1238 private static class OffsetHolder {
1239 static final long rtypeOffset
1240 = UNSAFE.objectFieldOffset(MethodType.class, "rtype");
1241
1242 static final long ptypesOffset
1243 = UNSAFE.objectFieldOffset(MethodType.class, "ptypes");
1244 }
1245
1246 /**
1247 * Resolves and initializes a {@code MethodType} object
1248 * after serialization.
1249 * @return the fully initialized {@code MethodType} object
1250 */
1251 private Object readResolve() {
1252 // Do not use a trusted path for deserialization:
1253 // return makeImpl(rtype, ptypes, true);
1254 // Verify all operands, and make sure ptypes is unshared:
1255 try {
1256 return methodType(rtype, ptypes);
1257 } finally {
1258 // Re-assign defaults in case this object escapes
1259 MethodType_init(void.class, NO_PTYPES);
1260 }
1261 }
1262
1263 /**
1264 * Simple implementation of weak concurrent intern set.
1265 *
1266 * @param <T> interned type
1267 */
1268 private static class ConcurrentWeakInternSet<T> {
1269
1270 private final ConcurrentMap<WeakEntry<T>, WeakEntry<T>> map;
1271 private final ReferenceQueue<T> stale;
1272
1273 public ConcurrentWeakInternSet() {
1274 this.map = new ConcurrentHashMap<>(512);
1275 this.stale = new ReferenceQueue<>();
1276 }
1277
1278 /**
1279 * Get the existing interned element.
1280 * This method returns null if no element is interned.
1281 *
1282 * @param elem element to look up
1283 * @return the interned element
1284 */
1285 public T get(T elem) {
1286 if (elem == null) throw new NullPointerException();
1287 expungeStaleElements();
1288
1289 WeakEntry<T> value = map.get(new WeakEntry<>(elem));
1290 if (value != null) {
1291 T res = value.get();
1292 if (res != null) {
1293 return res;
1294 }
1295 }
1296 return null;
1297 }
1298
1299 /**
1300 * Interns the element.
1301 * Always returns non-null element, matching the one in the intern set.
1302 * Under the race against another add(), it can return <i>different</i>
1303 * element, if another thread beats us to interning it.
1304 *
1305 * @param elem element to add
1306 * @return element that was actually added
1307 */
1308 public T add(T elem) {
1309 if (elem == null) throw new NullPointerException();
1310
1311 // Playing double race here, and so spinloop is required.
1312 // First race is with two concurrent updaters.
1313 // Second race is with GC purging weak ref under our feet.
1314 // Hopefully, we almost always end up with a single pass.
1315 T interned;
1316 WeakEntry<T> e = new WeakEntry<>(elem, stale);
1317 do {
1318 expungeStaleElements();
1319 WeakEntry<T> exist = map.putIfAbsent(e, e);
1320 interned = (exist == null) ? elem : exist.get();
1321 } while (interned == null);
1322 return interned;
1323 }
1324
1325 private void expungeStaleElements() {
1326 Reference<? extends T> reference;
1327 while ((reference = stale.poll()) != null) {
1328 map.remove(reference);
1329 }
1330 }
1331
1332 private static class WeakEntry<T> extends WeakReference<T> {
1333
1334 public final int hashcode;
1335
1336 public WeakEntry(T key, ReferenceQueue<T> queue) {
1337 super(key, queue);
1338 hashcode = key.hashCode();
1339 }
1340
1341 public WeakEntry(T key) {
1342 super(key);
1343 hashcode = key.hashCode();
1344 }
1345
1346 @Override
1347 public boolean equals(Object obj) {
1348 if (obj instanceof WeakEntry) {
1349 Object that = ((WeakEntry) obj).get();
1350 Object mine = get();
1351 return (that == null || mine == null) ? (this == obj) : mine.equals(that);
1352 }
1353 return false;
1354 }
1355
1356 @Override
1357 public int hashCode() {
1358 return hashcode;
1359 }
1360
1361 }
1362 }
1363
1364 }
1365