1 /*
2 * Copyright (c) 2008, 2012, 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 sun.invoke.util.Wrapper;
29 import java.lang.ref.WeakReference;
30 import java.lang.ref.Reference;
31 import java.lang.ref.ReferenceQueue;
32 import java.util.Arrays;
33 import java.util.Collections;
34 import java.util.List;
35 import java.util.Objects;
36 import java.util.concurrent.ConcurrentMap;
37 import java.util.concurrent.ConcurrentHashMap;
38 import sun.invoke.util.BytecodeDescriptor;
39 import static java.lang.invoke.MethodHandleStatics.*;
40 import sun.invoke.util.VerifyType;
41
42 /**
43 * A method type represents the arguments and return type accepted and
44 * returned by a method handle, or the arguments and return type passed
45 * and expected by a method handle caller. Method types must be properly
46 * matched between a method handle and all its callers,
47 * and the JVM's operations enforce this matching at, specifically
48 * during calls to {@link MethodHandle#invokeExact MethodHandle.invokeExact}
49 * and {@link MethodHandle#invoke MethodHandle.invoke}, and during execution
50 * of {@code invokedynamic} instructions.
51 * <p>
52 * The structure is a return type accompanied by any number of parameter types.
53 * The types (primitive, {@code void}, and reference) are represented by {@link Class} objects.
54 * (For ease of exposition, we treat {@code void} as if it were a type.
55 * In fact, it denotes the absence of a return type.)
56 * <p>
57 * All instances of {@code MethodType} are immutable.
58 * Two instances are completely interchangeable if they compare equal.
59 * Equality depends on pairwise correspondence of the return and parameter types and on nothing else.
60 * <p>
61 * This type can be created only by factory methods.
62 * All factory methods may cache values, though caching is not guaranteed.
63 * Some factory methods are static, while others are virtual methods which
64 * modify precursor method types, e.g., by changing a selected parameter.
65 * <p>
66 * Factory methods which operate on groups of parameter types
67 * are systematically presented in two versions, so that both Java arrays and
68 * Java lists can be used to work with groups of parameter types.
69 * The query methods {@code parameterArray} and {@code parameterList}
70 * also provide a choice between arrays and lists.
71 * <p>
72 * {@code MethodType} objects are sometimes derived from bytecode instructions
73 * such as {@code invokedynamic}, specifically from the type descriptor strings associated
74 * with the instructions in a class file's constant pool.
75 * <p>
76 * Like classes and strings, method types can also be represented directly
77 * in a class file's constant pool as constants.
78 * A method type may be loaded by an {@code ldc} instruction which refers
79 * to a suitable {@code CONSTANT_MethodType} constant pool entry.
80 * The entry refers to a {@code CONSTANT_Utf8} spelling for the descriptor string.
81 * For more details, see the <a href="package-summary.html#mtcon">package summary</a>.
82 * <p>
83 * When the JVM materializes a {@code MethodType} from a descriptor string,
84 * all classes named in the descriptor must be accessible, and will be loaded.
85 * (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.)
86 * This loading may occur at any time before the {@code MethodType} object is first derived.
87 * @author John Rose, JSR 292 EG
88 */
89 public final
90 class MethodType implements java.io.Serializable {
91 private static final long serialVersionUID = 292L; // {rtype, {ptype...}}
92
93 // The rtype and ptypes fields define the structural identity of the method type:
94 private final Class<?> rtype;
95 private final Class<?>[] ptypes;
96
97 // The remaining fields are caches of various sorts:
98 private MethodTypeForm form; // erased form, plus cached data about primitives
99 private MethodType wrapAlt; // alternative wrapped/unwrapped version
100 private Invokers invokers; // cache of handy higher-order adapters
101 private String methodDescriptor;
102
103 /**
104 * Check the given parameters for validity and store them into the final fields.
105 */
106 private MethodType(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
107 checkRtype(rtype);
108 checkPtypes(ptypes);
109 this.rtype = rtype;
110 // defensively copy the array passed in by the user
111 this.ptypes = trusted ? ptypes : Arrays.copyOf(ptypes, ptypes.length);
112 }
113
114 /**
115 * Don't check the given parameters for validity - creates MethodType for usage as searching key only.
116 */
117 private MethodType(Class<?>[] ptypes, Class<?> rtype) {
118 this.rtype = rtype;
119 this.ptypes = ptypes;
120 }
121
122 /*trusted*/ MethodTypeForm form() { return form; }
123 /*trusted*/ Class<?> rtype() { return rtype; }
124 /*trusted*/ Class<?>[] ptypes() { return ptypes; }
125
126 void setForm(MethodTypeForm f) { form = f; }
127
128 /** This number, mandated by the JVM spec as 255,
129 * is the maximum number of <em>slots</em>
130 * that any Java method can receive in its argument list.
131 * It limits both JVM signatures and method type objects.
132 * The longest possible invocation will look like
133 * {@code staticMethod(arg1, arg2, ..., arg255)} or
134 * {@code x.virtualMethod(arg1, arg2, ..., arg254)}.
135 */
136 /*non-public*/ static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec.
137
138 /** This number is the maximum arity of a method handle, 254.
139 * It is derived from the absolute JVM-imposed arity by subtracting one,
140 * which is the slot occupied by the method handle itself at the
141 * beginning of the argument list used to invoke the method handle.
142 * The longest possible invocation will look like
143 * {@code mh.invoke(arg1, arg2, ..., arg254)}.
144 */
145 // Issue: Should we allow MH.invokeWithArguments to go to the full 255?
146 /*non-public*/ static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver
147
148 /** This number is the maximum arity of a method handle invoker, 253.
149 * It is derived from the absolute JVM-imposed arity by subtracting two,
150 * which are the slots occupied by invoke method handle, and the the
151 * target method handle, which are both at the beginning of the argument
152 * list used to invoke the target method handle.
153 * The longest possible invocation will look like
154 * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}.
155 */
156 /*non-public*/ static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker
157
158 private static void checkRtype(Class<?> rtype) {
159 Objects.requireNonNull(rtype);
160 }
161 private static void checkPtype(Class<?> ptype) {
162 Objects.requireNonNull(ptype);
163 if (ptype == void.class)
164 throw newIllegalArgumentException("parameter type cannot be void");
165 }
166 /** Return number of extra slots (count of long/double args). */
167 private static int checkPtypes(Class<?>[] ptypes) {
168 int slots = 0;
169 for (Class<?> ptype : ptypes) {
170 checkPtype(ptype);
171 if (ptype == double.class || ptype == long.class) {
172 slots++;
173 }
174 }
175 checkSlotCount(ptypes.length + slots);
176 return slots;
177 }
178 static void checkSlotCount(int count) {
179 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0);
180 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work:
181 if ((count & MAX_JVM_ARITY) != count)
182 throw newIllegalArgumentException("bad parameter count "+count);
183 }
184 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) {
185 if (num instanceof Integer) num = "bad index: "+num;
186 return new IndexOutOfBoundsException(num.toString());
187 }
188
189 static final ConcurrentWeakInternSet<MethodType> internTable = new ConcurrentWeakInternSet<>();
190
191 static final Class<?>[] NO_PTYPES = {};
192
193 /**
194 * Finds or creates an instance of the given method type.
195 * @param rtype the return type
196 * @param ptypes the parameter types
197 * @return a method type with the given components
198 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
199 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
200 */
201 public static
202 MethodType methodType(Class<?> rtype, Class<?>[] ptypes) {
203 return makeImpl(rtype, ptypes, false);
204 }
205
206 /**
207 * Finds or creates a method type with the given components.
208 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
209 * @param rtype the return type
210 * @param ptypes the parameter types
211 * @return a method type with the given components
212 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
213 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
214 */
215 public static
216 MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) {
217 boolean notrust = false; // random List impl. could return evil ptypes array
218 return makeImpl(rtype, listToArray(ptypes), notrust);
219 }
220
221 private static Class<?>[] listToArray(List<Class<?>> ptypes) {
222 // sanity check the size before the toArray call, since size might be huge
223 checkSlotCount(ptypes.size());
224 return ptypes.toArray(NO_PTYPES);
225 }
226
227 /**
228 * Finds or creates a method type with the given components.
229 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
230 * The leading parameter type is prepended to the remaining array.
231 * @param rtype the return type
232 * @param ptype0 the first parameter type
233 * @param ptypes the remaining parameter types
234 * @return a method type with the given components
235 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null
236 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class}
237 */
238 public static
239 MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) {
240 Class<?>[] ptypes1 = new Class<?>[1+ptypes.length];
241 ptypes1[0] = ptype0;
242 System.arraycopy(ptypes, 0, ptypes1, 1, ptypes.length);
243 return makeImpl(rtype, ptypes1, true);
244 }
245
246 /**
247 * Finds or creates a method type with the given components.
248 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
249 * The resulting method has no parameter types.
250 * @param rtype the return type
251 * @return a method type with the given return value
252 * @throws NullPointerException if {@code rtype} is null
253 */
254 public static
255 MethodType methodType(Class<?> rtype) {
256 return makeImpl(rtype, NO_PTYPES, true);
257 }
258
259 /**
260 * Finds or creates a method type with the given components.
261 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
262 * The resulting method has the single given parameter type.
263 * @param rtype the return type
264 * @param ptype0 the parameter type
265 * @return a method type with the given return value and parameter type
266 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null
267 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class}
268 */
269 public static
270 MethodType methodType(Class<?> rtype, Class<?> ptype0) {
271 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true);
272 }
273
274 /**
275 * Finds or creates a method type with the given components.
276 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
277 * The resulting method has the same parameter types as {@code ptypes},
278 * and the specified return type.
279 * @param rtype the return type
280 * @param ptypes the method type which supplies the parameter types
281 * @return a method type with the given components
282 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null
283 */
284 public static
285 MethodType methodType(Class<?> rtype, MethodType ptypes) {
286 return makeImpl(rtype, ptypes.ptypes, true);
287 }
288
289 /**
290 * Sole factory method to find or create an interned method type.
291 * @param rtype desired return type
292 * @param ptypes desired parameter types
293 * @param trusted whether the ptypes can be used without cloning
294 * @return the unique method type of the desired structure
295 */
296 /*trusted*/ static
297 MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
298 MethodType mt = internTable.get(new MethodType(ptypes, rtype));
299 if (mt != null)
300 return mt;
301 if (ptypes.length == 0) {
302 ptypes = NO_PTYPES; trusted = true;
303 }
304 mt = new MethodType(rtype, ptypes, trusted);
305 // promote the object to the Real Thing, and reprobe
306 mt.form = MethodTypeForm.findForm(mt);
307 return internTable.add(mt);
308 }
309 private static final MethodType[] objectOnlyTypes = new MethodType[20];
310
311 /**
312 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array.
313 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
314 * All parameters and the return type will be {@code Object},
315 * except the final array parameter if any, which will be {@code Object[]}.
316 * @param objectArgCount number of parameters (excluding the final array parameter if any)
317 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]}
318 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments
319 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true)
320 * @see #genericMethodType(int)
321 */
322 public static
323 MethodType genericMethodType(int objectArgCount, boolean finalArray) {
324 MethodType mt;
325 checkSlotCount(objectArgCount);
326 int ivarargs = (!finalArray ? 0 : 1);
327 int ootIndex = objectArgCount*2 + ivarargs;
328 if (ootIndex < objectOnlyTypes.length) {
329 mt = objectOnlyTypes[ootIndex];
330 if (mt != null) return mt;
331 }
332 Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs];
333 Arrays.fill(ptypes, Object.class);
334 if (ivarargs != 0) ptypes[objectArgCount] = Object[].class;
335 mt = makeImpl(Object.class, ptypes, true);
336 if (ootIndex < objectOnlyTypes.length) {
337 objectOnlyTypes[ootIndex] = mt; // cache it here also!
338 }
339 return mt;
340 }
341
342 /**
343 * Finds or creates a method type whose components are all {@code Object}.
344 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
345 * All parameters and the return type will be Object.
346 * @param objectArgCount number of parameters
347 * @return a generally applicable method type, for all calls of the given argument count
348 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255
349 * @see #genericMethodType(int, boolean)
350 */
351 public static
352 MethodType genericMethodType(int objectArgCount) {
353 return genericMethodType(objectArgCount, false);
354 }
355
356 /**
357 * Finds or creates a method type with a single different parameter type.
358 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
359 * @param num the index (zero-based) of the parameter type to change
360 * @param nptype a new parameter type to replace the old one with
361 * @return the same type, except with the selected parameter changed
362 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
363 * @throws IllegalArgumentException if {@code nptype} is {@code void.class}
364 * @throws NullPointerException if {@code nptype} is null
365 */
366 public MethodType changeParameterType(int num, Class<?> nptype) {
367 if (parameterType(num) == nptype) return this;
368 checkPtype(nptype);
369 Class<?>[] nptypes = ptypes.clone();
370 nptypes[num] = nptype;
371 return makeImpl(rtype, nptypes, true);
372 }
373
374 /**
375 * Finds or creates a method type with additional parameter types.
376 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
377 * @param num the position (zero-based) of the inserted parameter type(s)
378 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
379 * @return the same type, except with the selected parameter(s) inserted
380 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
381 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
382 * or if the resulting method type would have more than 255 parameter slots
383 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
384 */
385 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) {
386 int len = ptypes.length;
387 if (num < 0 || num > len)
388 throw newIndexOutOfBoundsException(num);
389 int ins = checkPtypes(ptypesToInsert);
390 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins);
391 int ilen = ptypesToInsert.length;
392 if (ilen == 0) return this;
393 Class<?>[] nptypes = Arrays.copyOfRange(ptypes, 0, len+ilen);
394 System.arraycopy(nptypes, num, nptypes, num+ilen, len-num);
395 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen);
396 return makeImpl(rtype, nptypes, true);
397 }
398
399 /**
400 * Finds or creates a method type with additional parameter types.
401 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
402 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
403 * @return the same type, except with the selected parameter(s) appended
404 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
405 * or if the resulting method type would have more than 255 parameter slots
406 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
407 */
408 public MethodType appendParameterTypes(Class<?>... ptypesToInsert) {
409 return insertParameterTypes(parameterCount(), ptypesToInsert);
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 num the position (zero-based) of the inserted parameter type(s)
416 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
417 * @return the same type, except with the selected parameter(s) inserted
418 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
419 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
420 * or if the resulting method type would have more than 255 parameter slots
421 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
422 */
423 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) {
424 return insertParameterTypes(num, listToArray(ptypesToInsert));
425 }
426
427 /**
428 * Finds or creates a method type with additional parameter types.
429 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
430 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
431 * @return the same type, except with the selected parameter(s) appended
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 appendParameterTypes(List<Class<?>> ptypesToInsert) {
437 return insertParameterTypes(parameterCount(), ptypesToInsert);
438 }
439
440 /**
441 * Finds or creates a method type with modified parameter types.
442 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
443 * @param start the position (zero-based) of the first replaced parameter type(s)
444 * @param end the position (zero-based) after the last replaced parameter type(s)
445 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
446 * @return the same type, except with the selected parameter(s) replaced
447 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
448 * or if {@code end} is negative or greater than {@code parameterCount()}
449 * or if {@code start} is greater than {@code end}
450 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
451 * or if the resulting method type would have more than 255 parameter slots
452 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
453 */
454 /*non-public*/ MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) {
455 if (start == end)
456 return insertParameterTypes(start, ptypesToInsert);
457 int len = ptypes.length;
458 if (!(0 <= start && start <= end && end <= len))
459 throw newIndexOutOfBoundsException("start="+start+" end="+end);
460 int ilen = ptypesToInsert.length;
461 if (ilen == 0)
462 return dropParameterTypes(start, end);
463 return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert);
464 }
465
466 /**
467 * Finds or creates a method type with some parameter types omitted.
468 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
469 * @param start the index (zero-based) of the first parameter type to remove
470 * @param end the index (greater than {@code start}) of the first parameter type after not to remove
471 * @return the same type, except with the selected parameter(s) removed
472 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
473 * or if {@code end} is negative or greater than {@code parameterCount()}
474 * or if {@code start} is greater than {@code end}
475 */
476 public MethodType dropParameterTypes(int start, int end) {
477 int len = ptypes.length;
478 if (!(0 <= start && start <= end && end <= len))
479 throw newIndexOutOfBoundsException("start="+start+" end="+end);
480 if (start == end) return this;
481 Class<?>[] nptypes;
482 if (start == 0) {
483 if (end == len) {
484 // drop all parameters
485 nptypes = NO_PTYPES;
486 } else {
487 // drop initial parameter(s)
488 nptypes = Arrays.copyOfRange(ptypes, end, len);
489 }
490 } else {
491 if (end == len) {
492 // drop trailing parameter(s)
493 nptypes = Arrays.copyOfRange(ptypes, 0, start);
494 } else {
495 int tail = len - end;
496 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail);
497 System.arraycopy(ptypes, end, nptypes, start, tail);
498 }
499 }
500 return makeImpl(rtype, nptypes, true);
501 }
502
503 /**
504 * Finds or creates a method type with a different return type.
505 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
506 * @param nrtype a return parameter type to replace the old one with
507 * @return the same type, except with the return type change
508 * @throws NullPointerException if {@code nrtype} is null
509 */
510 public MethodType changeReturnType(Class<?> nrtype) {
511 if (returnType() == nrtype) return this;
512 return makeImpl(nrtype, ptypes, true);
513 }
514
515 /**
516 * Reports if this type contains a primitive argument or return value.
517 * The return type {@code void} counts as a primitive.
518 * @return true if any of the types are primitives
519 */
520 public boolean hasPrimitives() {
521 return form.hasPrimitives();
522 }
523
524 /**
525 * Reports if this type contains a wrapper argument or return value.
526 * Wrappers are types which box primitive values, such as {@link Integer}.
527 * The reference type {@code java.lang.Void} counts as a wrapper,
528 * if it occurs as a return type.
529 * @return true if any of the types are wrappers
530 */
531 public boolean hasWrappers() {
532 return unwrap() != this;
533 }
534
535 /**
536 * Erases all reference types to {@code Object}.
537 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
538 * All primitive types (including {@code void}) will remain unchanged.
539 * @return a version of the original type with all reference types replaced
540 */
541 public MethodType erase() {
542 return form.erasedType();
543 }
544
545 /**
546 * Erases all reference types to {@code Object}, and all subword types to {@code int}.
547 * This is the reduced type polymorphism used by private methods
548 * such as {@link MethodHandle#invokeBasic invokeBasic}.
549 * @return a version of the original type with all reference and subword types replaced
550 */
551 /*non-public*/ MethodType basicType() {
552 return form.basicType();
553 }
554
555 /**
556 * @return a version of the original type with MethodHandle prepended as the first argument
557 */
558 /*non-public*/ MethodType invokerType() {
559 return insertParameterTypes(0, MethodHandle.class);
560 }
561
562 /**
563 * Converts all types, both reference and primitive, to {@code Object}.
564 * Convenience method for {@link #genericMethodType(int) genericMethodType}.
565 * The expression {@code type.wrap().erase()} produces the same value
566 * as {@code type.generic()}.
567 * @return a version of the original type with all types replaced
568 */
569 public MethodType generic() {
570 return genericMethodType(parameterCount());
571 }
572
573 /**
574 * Converts all primitive types to their corresponding wrapper types.
575 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
576 * All reference types (including wrapper types) will remain unchanged.
577 * A {@code void} return type is changed to the type {@code java.lang.Void}.
578 * The expression {@code type.wrap().erase()} produces the same value
579 * as {@code type.generic()}.
580 * @return a version of the original type with all primitive types replaced
581 */
582 public MethodType wrap() {
583 return hasPrimitives() ? wrapWithPrims(this) : this;
584 }
585
586 /**
587 * Converts all wrapper types to their corresponding primitive types.
588 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
589 * All primitive types (including {@code void}) will remain unchanged.
590 * A return type of {@code java.lang.Void} is changed to {@code void}.
591 * @return a version of the original type with all wrapper types replaced
592 */
593 public MethodType unwrap() {
594 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this);
595 return unwrapWithNoPrims(noprims);
596 }
597
598 private static MethodType wrapWithPrims(MethodType pt) {
599 assert(pt.hasPrimitives());
600 MethodType wt = pt.wrapAlt;
601 if (wt == null) {
602 // fill in lazily
603 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP, MethodTypeForm.WRAP);
604 assert(wt != null);
605 pt.wrapAlt = wt;
606 }
607 return wt;
608 }
609
610 private static MethodType unwrapWithNoPrims(MethodType wt) {
611 assert(!wt.hasPrimitives());
612 MethodType uwt = wt.wrapAlt;
613 if (uwt == null) {
614 // fill in lazily
615 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP, MethodTypeForm.UNWRAP);
616 if (uwt == null)
617 uwt = wt; // type has no wrappers or prims at all
618 wt.wrapAlt = uwt;
619 }
620 return uwt;
621 }
622
623 /**
624 * Returns the parameter type at the specified index, within this method type.
625 * @param num the index (zero-based) of the desired parameter type
626 * @return the selected parameter type
627 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
628 */
629 public Class<?> parameterType(int num) {
630 return ptypes[num];
631 }
632 /**
633 * Returns the number of parameter types in this method type.
634 * @return the number of parameter types
635 */
636 public int parameterCount() {
637 return ptypes.length;
638 }
639 /**
640 * Returns the return type of this method type.
641 * @return the return type
642 */
643 public Class<?> returnType() {
644 return rtype;
645 }
646
647 /**
648 * Presents the parameter types as a list (a convenience method).
649 * The list will be immutable.
650 * @return the parameter types (as an immutable list)
651 */
652 public List<Class<?>> parameterList() {
653 return Collections.unmodifiableList(Arrays.asList(ptypes));
654 }
655
656 /*non-public*/ Class<?> lastParameterType() {
657 int len = ptypes.length;
658 return len == 0 ? void.class : ptypes[len-1];
659 }
660
661 /**
662 * Presents the parameter types as an array (a convenience method).
663 * Changes to the array will not result in changes to the type.
664 * @return the parameter types (as a fresh copy if necessary)
665 */
666 public Class<?>[] parameterArray() {
667 return ptypes.clone();
668 }
669
670 /**
671 * Compares the specified object with this type for equality.
672 * That is, it returns <tt>true</tt> if and only if the specified object
673 * is also a method type with exactly the same parameters and return type.
674 * @param x object to compare
675 * @see Object#equals(Object)
676 */
677 @Override
678 public boolean equals(Object x) {
679 return this == x || x instanceof MethodType && equals((MethodType)x);
680 }
681
682 private boolean equals(MethodType that) {
683 return this.rtype == that.rtype
684 && Arrays.equals(this.ptypes, that.ptypes);
685 }
686
687 /**
688 * Returns the hash code value for this method type.
689 * It is defined to be the same as the hashcode of a List
690 * whose elements are the return type followed by the
691 * parameter types.
692 * @return the hash code value for this method type
693 * @see Object#hashCode()
694 * @see #equals(Object)
695 * @see List#hashCode()
696 */
697 @Override
698 public int hashCode() {
699 int hashCode = 31 + rtype.hashCode();
700 for (Class<?> ptype : ptypes)
701 hashCode = 31*hashCode + ptype.hashCode();
702 return hashCode;
703 }
704
705 /**
706 * Returns a string representation of the method type,
707 * of the form {@code "(PT0,PT1...)RT"}.
708 * The string representation of a method type is a
709 * parenthesis enclosed, comma separated list of type names,
710 * followed immediately by the return type.
711 * <p>
712 * Each type is represented by its
713 * {@link java.lang.Class#getSimpleName simple name}.
714 */
715 @Override
716 public String toString() {
717 StringBuilder sb = new StringBuilder();
718 sb.append("(");
719 for (int i = 0; i < ptypes.length; i++) {
720 if (i > 0) sb.append(",");
721 sb.append(ptypes[i].getSimpleName());
722 }
723 sb.append(")");
724 sb.append(rtype.getSimpleName());
725 return sb.toString();
726 }
727
728
729 /*non-public*/
730 boolean isViewableAs(MethodType newType) {
731 if (!VerifyType.isNullConversion(returnType(), newType.returnType()))
732 return false;
733 int argc = parameterCount();
734 if (argc != newType.parameterCount())
735 return false;
736 for (int i = 0; i < argc; i++) {
737 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i)))
738 return false;
739 }
740 return true;
741 }
742 /*non-public*/
743 boolean isCastableTo(MethodType newType) {
744 int argc = parameterCount();
745 if (argc != newType.parameterCount())
746 return false;
747 return true;
748 }
749 /*non-public*/
750 boolean isConvertibleTo(MethodType newType) {
751 if (!canConvert(returnType(), newType.returnType()))
752 return false;
753 int argc = parameterCount();
754 if (argc != newType.parameterCount())
755 return false;
756 for (int i = 0; i < argc; i++) {
757 if (!canConvert(newType.parameterType(i), parameterType(i)))
758 return false;
759 }
760 return true;
761 }
762 /*non-public*/
763 static boolean canConvert(Class<?> src, Class<?> dst) {
764 // short-circuit a few cases:
765 if (src == dst || dst == Object.class) return true;
766 // the remainder of this logic is documented in MethodHandle.asType
767 if (src.isPrimitive()) {
768 // can force void to an explicit null, a la reflect.Method.invoke
769 // can also force void to a primitive zero, by analogy
770 if (src == void.class) return true; //or !dst.isPrimitive()?
771 Wrapper sw = Wrapper.forPrimitiveType(src);
772 if (dst.isPrimitive()) {
773 // P->P must widen
774 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw);
775 } else {
776 // P->R must box and widen
777 return dst.isAssignableFrom(sw.wrapperType());
778 }
779 } else if (dst.isPrimitive()) {
780 // any value can be dropped
781 if (dst == void.class) return true;
782 Wrapper dw = Wrapper.forPrimitiveType(dst);
783 // R->P must be able to unbox (from a dynamically chosen type) and widen
784 // For example:
785 // Byte/Number/Comparable/Object -> dw:Byte -> byte.
786 // Character/Comparable/Object -> dw:Character -> char
787 // Boolean/Comparable/Object -> dw:Boolean -> boolean
788 // This means that dw must be cast-compatible with src.
789 if (src.isAssignableFrom(dw.wrapperType())) {
790 return true;
791 }
792 // The above does not work if the source reference is strongly typed
793 // to a wrapper whose primitive must be widened. For example:
794 // Byte -> unbox:byte -> short/int/long/float/double
795 // Character -> unbox:char -> int/long/float/double
796 if (Wrapper.isWrapperType(src) &&
797 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) {
798 // can unbox from src and then widen to dst
799 return true;
800 }
801 // We have already covered cases which arise due to runtime unboxing
802 // of a reference type which covers several wrapper types:
803 // Object -> cast:Integer -> unbox:int -> long/float/double
804 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double
805 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a
806 // subclass of Number which wraps a value that can convert to char.
807 // Since there is none, we don't need an extra check here to cover char or boolean.
808 return false;
809 } else {
810 // R->R always works, since null is always valid dynamically
811 return true;
812 }
813 }
814
815 /// Queries which have to do with the bytecode architecture
816
817 /** Reports the number of JVM stack slots required to invoke a method
818 * of this type. Note that (for historical reasons) the JVM requires
819 * a second stack slot to pass long and double arguments.
820 * So this method returns {@link #parameterCount() parameterCount} plus the
821 * number of long and double parameters (if any).
822 * <p>
823 * This method is included for the benfit of applications that must
824 * generate bytecodes that process method handles and invokedynamic.
825 * @return the number of JVM stack slots for this type's parameters
826 */
827 /*non-public*/ int parameterSlotCount() {
828 return form.parameterSlotCount();
829 }
830
831 /*non-public*/ Invokers invokers() {
832 Invokers inv = invokers;
833 if (inv != null) return inv;
834 invokers = inv = new Invokers(this);
835 return inv;
836 }
837
838 /** Reports the number of JVM stack slots which carry all parameters including and after
839 * the given position, which must be in the range of 0 to
840 * {@code parameterCount} inclusive. Successive parameters are
841 * more shallowly stacked, and parameters are indexed in the bytecodes
842 * according to their trailing edge. Thus, to obtain the depth
843 * in the outgoing call stack of parameter {@code N}, obtain
844 * the {@code parameterSlotDepth} of its trailing edge
845 * at position {@code N+1}.
846 * <p>
847 * Parameters of type {@code long} and {@code double} occupy
848 * two stack slots (for historical reasons) and all others occupy one.
849 * Therefore, the number returned is the number of arguments
850 * <em>including</em> and <em>after</em> the given parameter,
851 * <em>plus</em> the number of long or double arguments
852 * at or after after the argument for the given parameter.
853 * <p>
854 * This method is included for the benfit of applications that must
855 * generate bytecodes that process method handles and invokedynamic.
856 * @param num an index (zero-based, inclusive) within the parameter types
857 * @return the index of the (shallowest) JVM stack slot transmitting the
858 * given parameter
859 * @throws IllegalArgumentException if {@code num} is negative or greater than {@code parameterCount()}
860 */
861 /*non-public*/ int parameterSlotDepth(int num) {
862 if (num < 0 || num > ptypes.length)
863 parameterType(num); // force a range check
864 return form.parameterToArgSlot(num-1);
865 }
866
867 /** Reports the number of JVM stack slots required to receive a return value
868 * from a method of this type.
869 * If the {@link #returnType() return type} is void, it will be zero,
870 * else if the return type is long or double, it will be two, else one.
871 * <p>
872 * This method is included for the benfit of applications that must
873 * generate bytecodes that process method handles and invokedynamic.
874 * @return the number of JVM stack slots (0, 1, or 2) for this type's return value
875 * Will be removed for PFD.
876 */
877 /*non-public*/ int returnSlotCount() {
878 return form.returnSlotCount();
879 }
880
881 /**
882 * Finds or creates an instance of a method type, given the spelling of its bytecode descriptor.
883 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
884 * Any class or interface name embedded in the descriptor string
885 * will be resolved by calling {@link ClassLoader#loadClass(java.lang.String)}
886 * on the given loader (or if it is null, on the system class loader).
887 * <p>
888 * Note that it is possible to encounter method types which cannot be
889 * constructed by this method, because their component types are
890 * not all reachable from a common class loader.
891 * <p>
892 * This method is included for the benfit of applications that must
893 * generate bytecodes that process method handles and {@code invokedynamic}.
894 * @param descriptor a bytecode-level type descriptor string "(T...)T"
895 * @param loader the class loader in which to look up the types
896 * @return a method type matching the bytecode-level type descriptor
897 * @throws NullPointerException if the string is null
898 * @throws IllegalArgumentException if the string is not well-formed
899 * @throws TypeNotPresentException if a named type cannot be found
900 */
901 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader)
902 throws IllegalArgumentException, TypeNotPresentException
903 {
904 if (!descriptor.startsWith("(") || // also generates NPE if needed
905 descriptor.indexOf(')') < 0 ||
906 descriptor.indexOf('.') >= 0)
907 throw new IllegalArgumentException("not a method descriptor: "+descriptor);
908 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader);
909 Class<?> rtype = types.remove(types.size() - 1);
910 checkSlotCount(types.size());
911 Class<?>[] ptypes = listToArray(types);
912 return makeImpl(rtype, ptypes, true);
913 }
914
915 /**
916 * Produces a bytecode descriptor representation of the method type.
917 * <p>
918 * Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}.
919 * Two distinct classes which share a common name but have different class loaders
920 * will appear identical when viewed within descriptor strings.
921 * <p>
922 * This method is included for the benfit of applications that must
923 * generate bytecodes that process method handles and {@code invokedynamic}.
924 * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString},
925 * because the latter requires a suitable class loader argument.
926 * @return the bytecode type descriptor representation
927 */
928 public String toMethodDescriptorString() {
929 String desc = methodDescriptor;
930 if (desc == null) {
931 desc = BytecodeDescriptor.unparse(this);
932 methodDescriptor = desc;
933 }
934 return desc;
935 }
936
937 /*non-public*/ static String toFieldDescriptorString(Class<?> cls) {
938 return BytecodeDescriptor.unparse(cls);
939 }
940
941 /// Serialization.
942
943 /**
944 * There are no serializable fields for {@code MethodType}.
945 */
946 private static final java.io.ObjectStreamField[] serialPersistentFields = { };
947
948 /**
949 * Save the {@code MethodType} instance to a stream.
950 *
951 * @serialData
952 * For portability, the serialized format does not refer to named fields.
953 * Instead, the return type and parameter type arrays are written directly
954 * from the {@code writeObject} method, using two calls to {@code s.writeObject}
955 * as follows:
956 * <blockquote><pre>
957 s.writeObject(this.returnType());
958 s.writeObject(this.parameterArray());
959 * </pre></blockquote>
960 * <p>
961 * The deserialized field values are checked as if they were
962 * provided to the factory method {@link #methodType(Class,Class[]) methodType}.
963 * For example, null values, or {@code void} parameter types,
964 * will lead to exceptions during deserialization.
965 * @param s the stream to write the object to
966 * @throws java.io.IOException if there is a problem writing the object
967 */
968 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
969 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array
970 s.writeObject(returnType());
971 s.writeObject(parameterArray());
972 }
973
974 /**
975 * Reconstitute the {@code MethodType} instance from a stream (that is,
976 * deserialize it).
977 * This instance is a scratch object with bogus final fields.
978 * It provides the parameters to the factory method called by
979 * {@link #readResolve readResolve}.
980 * After that call it is discarded.
981 * @param s the stream to read the object from
982 * @throws java.io.IOException if there is a problem reading the object
983 * @throws ClassNotFoundException if one of the component classes cannot be resolved
984 * @see #MethodType()
985 * @see #readResolve
986 * @see #writeObject
987 */
988 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
989 s.defaultReadObject(); // requires serialPersistentFields to be an empty array
990
991 Class<?> returnType = (Class<?>) s.readObject();
992 Class<?>[] parameterArray = (Class<?>[]) s.readObject();
993
994 // Probably this object will never escape, but let's check
995 // the field values now, just to be sure.
996 checkRtype(returnType);
997 checkPtypes(parameterArray);
998
999 parameterArray = parameterArray.clone(); // make sure it is unshared
1000 MethodType_init(returnType, parameterArray);
1001 }
1002
1003 /**
1004 * For serialization only.
1005 * Sets the final fields to null, pending {@code Unsafe.putObject}.
1006 */
1007 private MethodType() {
1008 this.rtype = null;
1009 this.ptypes = null;
1010 }
1011 private void MethodType_init(Class<?> rtype, Class<?>[] ptypes) {
1012 // In order to communicate these values to readResolve, we must
1013 // store them into the implementation-specific final fields.
1014 checkRtype(rtype);
1015 checkPtypes(ptypes);
1016 UNSAFE.putObject(this, rtypeOffset, rtype);
1017 UNSAFE.putObject(this, ptypesOffset, ptypes);
1018 }
1019
1020 // Support for resetting final fields while deserializing
1021 private static final long rtypeOffset, ptypesOffset;
1022 static {
1023 try {
1024 rtypeOffset = UNSAFE.objectFieldOffset
1025 (MethodType.class.getDeclaredField("rtype"));
1026 ptypesOffset = UNSAFE.objectFieldOffset
1027 (MethodType.class.getDeclaredField("ptypes"));
1028 } catch (Exception ex) {
1029 throw new Error(ex);
1030 }
1031 }
1032
1033 /**
1034 * Resolves and initializes a {@code MethodType} object
1035 * after serialization.
1036 * @return the fully initialized {@code MethodType} object
1037 */
1038 private Object readResolve() {
1039 // Do not use a trusted path for deserialization:
1040 //return makeImpl(rtype, ptypes, true);
1041 // Verify all operands, and make sure ptypes is unshared:
1042 return methodType(rtype, ptypes);
1043 }
1044
1045 /**
1046 * Simple implementation of weak concurrent intern set.
1047 *
1048 * @param <T> interned type
1049 */
1050 private static class ConcurrentWeakInternSet<T> {
1051
1052 private final ConcurrentMap<WeakEntry<T>, WeakEntry<T>> map;
1053 private final ReferenceQueue<T> stale;
1054
1055 public ConcurrentWeakInternSet() {
1056 this.map = new ConcurrentHashMap<>();
1057 this.stale = new ReferenceQueue<>();
1058 }
1059
1060 /**
1061 * Get the existing interned element.
1062 * This method returns null if no element is interned.
1063 *
1064 * @param elem element to look up
1065 * @return the interned element
1066 */
1067 public T get(T elem) {
1068 if (elem == null) throw new NullPointerException();
1069 expungeStaleElements();
1070
1071 WeakEntry<T> value = map.get(new WeakEntry<>(elem));
1072 if (value != null) {
1073 T res = value.get();
1074 if (res != null) {
1075 return res;
1076 }
1077 }
1078 return null;
1079 }
1080
1081 /**
1082 * Interns the element.
1083 * Always returns non-null element, matching the one in the intern set.
1084 * Under the race against another add(), it can return <i>different</i>
1085 * element, if another thread beats us to interning it.
1086 *
1087 * @param elem element to add
1088 * @return element that was actually added
1089 */
1090 public T add(T elem) {
1091 if (elem == null) throw new NullPointerException();
1092
1093 // Playing double race here, and so spinloop is required.
1094 // First race is with two concurrent updaters.
1095 // Second race is with GC purging weak ref under our feet.
1096 // Hopefully, we almost always end up with a single pass.
1097 T interned;
1098 WeakEntry<T> e = new WeakEntry<>(elem, stale);
1099 do {
1100 expungeStaleElements();
1101 WeakEntry<T> exist = map.putIfAbsent(e, e);
1102 interned = (exist == null) ? elem : exist.get();
1103 } while (interned == null);
1104 return interned;
1105 }
1106
1107 private void expungeStaleElements() {
1108 Reference<? extends T> reference;
1109 while ((reference = stale.poll()) != null) {
1110 map.remove(reference);
1111 }
1112 }
1113
1114 private static class WeakEntry<T> extends WeakReference<T> {
1115
1116 public final int hashcode;
1117
1118 public WeakEntry(T key, ReferenceQueue<T> queue) {
1119 super(key, queue);
1120 hashcode = key.hashCode();
1121 }
1122
1123 public WeakEntry(T key) {
1124 super(key);
1125 hashcode = key.hashCode();
1126 }
1127
1128 @Override
1129 public boolean equals(Object obj) {
1130 if (obj instanceof WeakEntry) {
1131 Object that = ((WeakEntry) obj).get();
1132 Object mine = get();
1133 return (that == null || mine == null) ? (this == obj) : mine.equals(that);
1134 }
1135 return false;
1136 }
1137
1138 @Override
1139 public int hashCode() {
1140 return hashcode;
1141 }
1142
1143 }
1144 }
1145
1146 }