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<?> rtype, Class<?>[] ptypes) {
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); // null check
160 }
161 private static int checkPtype(Class<?> ptype) {
162 Objects.requireNonNull(ptype); // null check
163 if (ptype == void.class)
164 throw newIllegalArgumentException("parameter type cannot be void");
165 if (ptype == double.class || ptype == long.class) return 1;
166 return 0;
167 }
168 /** Return number of extra slots (count of long/double args). */
169 private static int checkPtypes(Class<?>[] ptypes) {
170 int slots = 0;
171 for (Class<?> ptype : ptypes) {
172 slots += checkPtype(ptype);
173 }
174 checkSlotCount(ptypes.length + slots);
175 return slots;
176 }
177 static void checkSlotCount(int count) {
178 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0);
179 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work:
180 if ((count & MAX_JVM_ARITY) != count)
181 throw newIllegalArgumentException("bad parameter count "+count);
182 }
183 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) {
184 if (num instanceof Integer) num = "bad index: "+num;
185 return new IndexOutOfBoundsException(num.toString());
186 }
187
188 static final ConcurrentWeakInternSet<MethodType> internTable = new ConcurrentWeakInternSet<>();
189
190 static final Class<?>[] NO_PTYPES = {};
191
192 /**
193 * Finds or creates an instance of the given method type.
194 * @param rtype the return type
195 * @param ptypes the parameter types
196 * @return a method type with the given components
197 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
198 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
199 */
200 public static
201 MethodType methodType(Class<?> rtype, Class<?>[] ptypes) {
202 return makeImpl(rtype, ptypes, false);
203 }
204
205 /**
206 * Finds or creates a method type with the given components.
207 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
208 * @param rtype the return type
209 * @param ptypes the parameter types
210 * @return a method type with the given components
211 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
212 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
213 */
214 public static
215 MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) {
216 boolean notrust = false; // random List impl. could return evil ptypes array
217 return makeImpl(rtype, listToArray(ptypes), notrust);
218 }
219
220 private static Class<?>[] listToArray(List<Class<?>> ptypes) {
221 // sanity check the size before the toArray call, since size might be huge
222 checkSlotCount(ptypes.size());
223 return ptypes.toArray(NO_PTYPES);
224 }
225
226 /**
227 * Finds or creates a method type with the given components.
228 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
229 * The leading parameter type is prepended to the remaining array.
230 * @param rtype the return type
231 * @param ptype0 the first parameter type
232 * @param ptypes the remaining parameter types
233 * @return a method type with the given components
234 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null
235 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class}
236 */
237 public static
238 MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) {
239 Class<?>[] ptypes1 = new Class<?>[1+ptypes.length];
240 ptypes1[0] = ptype0;
241 System.arraycopy(ptypes, 0, ptypes1, 1, ptypes.length);
242 return makeImpl(rtype, ptypes1, true);
243 }
244
245 /**
246 * Finds or creates a method type with the given components.
247 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
248 * The resulting method has no parameter types.
249 * @param rtype the return type
250 * @return a method type with the given return value
251 * @throws NullPointerException if {@code rtype} is null
252 */
253 public static
254 MethodType methodType(Class<?> rtype) {
255 return makeImpl(rtype, NO_PTYPES, true);
256 }
257
258 /**
259 * Finds or creates a method type with the given components.
260 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
261 * The resulting method has the single given parameter type.
262 * @param rtype the return type
263 * @param ptype0 the parameter type
264 * @return a method type with the given return value and parameter type
265 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null
266 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class}
267 */
268 public static
269 MethodType methodType(Class<?> rtype, Class<?> ptype0) {
270 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true);
271 }
272
273 /**
274 * Finds or creates a method type with the given components.
275 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
276 * The resulting method has the same parameter types as {@code ptypes},
277 * and the specified return type.
278 * @param rtype the return type
279 * @param ptypes the method type which supplies the parameter types
280 * @return a method type with the given components
281 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null
282 */
283 public static
284 MethodType methodType(Class<?> rtype, MethodType ptypes) {
285 return makeImpl(rtype, ptypes.ptypes, true);
286 }
287
288 /**
289 * Sole factory method to find or create an interned method type.
290 * @param rtype desired return type
291 * @param ptypes desired parameter types
292 * @param trusted whether the ptypes can be used without cloning
293 * @return the unique method type of the desired structure
294 */
295 /*trusted*/ static
296 MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
297 MethodType mt = internTable.get(new MethodType(rtype, ptypes));
298 if (mt != null)
299 return mt;
300 if (ptypes.length == 0) {
301 ptypes = NO_PTYPES; trusted = true;
302 }
303 mt = new MethodType(rtype, ptypes, trusted);
304 // promote the object to the Real Thing, and reprobe
305 mt.form = MethodTypeForm.findForm(mt);
306 return internTable.add(mt);
307 }
308 private static final MethodType[] objectOnlyTypes = new MethodType[20];
309
310 /**
311 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array.
312 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
313 * All parameters and the return type will be {@code Object},
314 * except the final array parameter if any, which will be {@code Object[]}.
315 * @param objectArgCount number of parameters (excluding the final array parameter if any)
316 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]}
317 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments
318 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true)
319 * @see #genericMethodType(int)
320 */
321 public static
322 MethodType genericMethodType(int objectArgCount, boolean finalArray) {
323 MethodType mt;
324 checkSlotCount(objectArgCount);
325 int ivarargs = (!finalArray ? 0 : 1);
326 int ootIndex = objectArgCount*2 + ivarargs;
327 if (ootIndex < objectOnlyTypes.length) {
328 mt = objectOnlyTypes[ootIndex];
329 if (mt != null) return mt;
330 }
331 Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs];
332 Arrays.fill(ptypes, Object.class);
333 if (ivarargs != 0) ptypes[objectArgCount] = Object[].class;
334 mt = makeImpl(Object.class, ptypes, true);
335 if (ootIndex < objectOnlyTypes.length) {
336 objectOnlyTypes[ootIndex] = mt; // cache it here also!
337 }
338 return mt;
339 }
340
341 /**
342 * Finds or creates a method type whose components are all {@code Object}.
343 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
344 * All parameters and the return type will be Object.
345 * @param objectArgCount number of parameters
346 * @return a generally applicable method type, for all calls of the given argument count
347 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255
348 * @see #genericMethodType(int, boolean)
349 */
350 public static
351 MethodType genericMethodType(int objectArgCount) {
352 return genericMethodType(objectArgCount, false);
353 }
354
355 /**
356 * Finds or creates a method type with a single different parameter type.
357 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
358 * @param num the index (zero-based) of the parameter type to change
359 * @param nptype a new parameter type to replace the old one with
360 * @return the same type, except with the selected parameter changed
361 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
362 * @throws IllegalArgumentException if {@code nptype} is {@code void.class}
363 * @throws NullPointerException if {@code nptype} is null
364 */
365 public MethodType changeParameterType(int num, Class<?> nptype) {
366 if (parameterType(num) == nptype) return this;
367 checkPtype(nptype);
368 Class<?>[] nptypes = ptypes.clone();
369 nptypes[num] = nptype;
370 return makeImpl(rtype, nptypes, true);
371 }
372
373 /**
374 * Finds or creates a method type with additional parameter types.
375 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
376 * @param num the position (zero-based) of the inserted parameter type(s)
377 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
378 * @return the same type, except with the selected parameter(s) inserted
379 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
380 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
381 * or if the resulting method type would have more than 255 parameter slots
382 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
383 */
384 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) {
385 int len = ptypes.length;
386 if (num < 0 || num > len)
387 throw newIndexOutOfBoundsException(num);
388 int ins = checkPtypes(ptypesToInsert);
389 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins);
390 int ilen = ptypesToInsert.length;
391 if (ilen == 0) return this;
392 Class<?>[] nptypes = Arrays.copyOfRange(ptypes, 0, len+ilen);
393 System.arraycopy(nptypes, num, nptypes, num+ilen, len-num);
394 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen);
395 return makeImpl(rtype, nptypes, true);
396 }
397
398 /**
399 * Finds or creates a method type with additional parameter types.
400 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
401 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
402 * @return the same type, except with the selected parameter(s) appended
403 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
404 * or if the resulting method type would have more than 255 parameter slots
405 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
406 */
407 public MethodType appendParameterTypes(Class<?>... ptypesToInsert) {
408 return insertParameterTypes(parameterCount(), ptypesToInsert);
409 }
410
411 /**
412 * Finds or creates a method type with additional parameter types.
413 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
414 * @param num the position (zero-based) of the inserted parameter type(s)
415 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
416 * @return the same type, except with the selected parameter(s) inserted
417 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
418 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
419 * or if the resulting method type would have more than 255 parameter slots
420 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
421 */
422 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) {
423 return insertParameterTypes(num, listToArray(ptypesToInsert));
424 }
425
426 /**
427 * Finds or creates a method type with additional parameter types.
428 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
429 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
430 * @return the same type, except with the selected parameter(s) appended
431 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
432 * or if the resulting method type would have more than 255 parameter slots
433 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
434 */
435 public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) {
436 return insertParameterTypes(parameterCount(), ptypesToInsert);
437 }
438
439 /**
440 * Finds or creates a method type with modified parameter types.
441 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
442 * @param start the position (zero-based) of the first replaced parameter type(s)
443 * @param end the position (zero-based) after the last replaced parameter type(s)
444 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
445 * @return the same type, except with the selected parameter(s) replaced
446 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
447 * or if {@code end} is negative or greater than {@code parameterCount()}
448 * or if {@code start} is greater than {@code end}
449 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
450 * or if the resulting method type would have more than 255 parameter slots
451 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
452 */
453 /*non-public*/ MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) {
454 if (start == end)
455 return insertParameterTypes(start, ptypesToInsert);
456 int len = ptypes.length;
457 if (!(0 <= start && start <= end && end <= len))
458 throw newIndexOutOfBoundsException("start="+start+" end="+end);
459 int ilen = ptypesToInsert.length;
460 if (ilen == 0)
461 return dropParameterTypes(start, end);
462 return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert);
463 }
464
465 /**
466 * Finds or creates a method type with some parameter types omitted.
467 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
468 * @param start the index (zero-based) of the first parameter type to remove
469 * @param end the index (greater than {@code start}) of the first parameter type after not to remove
470 * @return the same type, except with the selected parameter(s) removed
471 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
472 * or if {@code end} is negative or greater than {@code parameterCount()}
473 * or if {@code start} is greater than {@code end}
474 */
475 public MethodType dropParameterTypes(int start, int end) {
476 int len = ptypes.length;
477 if (!(0 <= start && start <= end && end <= len))
478 throw newIndexOutOfBoundsException("start="+start+" end="+end);
479 if (start == end) return this;
480 Class<?>[] nptypes;
481 if (start == 0) {
482 if (end == len) {
483 // drop all parameters
484 nptypes = NO_PTYPES;
485 } else {
486 // drop initial parameter(s)
487 nptypes = Arrays.copyOfRange(ptypes, end, len);
488 }
489 } else {
490 if (end == len) {
491 // drop trailing parameter(s)
492 nptypes = Arrays.copyOfRange(ptypes, 0, start);
493 } else {
494 int tail = len - end;
495 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail);
496 System.arraycopy(ptypes, end, nptypes, start, tail);
497 }
498 }
499 return makeImpl(rtype, nptypes, true);
500 }
501
502 /**
503 * Finds or creates a method type with a different return type.
504 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
505 * @param nrtype a return parameter type to replace the old one with
506 * @return the same type, except with the return type change
507 * @throws NullPointerException if {@code nrtype} is null
508 */
509 public MethodType changeReturnType(Class<?> nrtype) {
510 if (returnType() == nrtype) return this;
511 return makeImpl(nrtype, ptypes, true);
512 }
513
514 /**
515 * Reports if this type contains a primitive argument or return value.
516 * The return type {@code void} counts as a primitive.
517 * @return true if any of the types are primitives
518 */
519 public boolean hasPrimitives() {
520 return form.hasPrimitives();
521 }
522
523 /**
524 * Reports if this type contains a wrapper argument or return value.
525 * Wrappers are types which box primitive values, such as {@link Integer}.
526 * The reference type {@code java.lang.Void} counts as a wrapper,
527 * if it occurs as a return type.
528 * @return true if any of the types are wrappers
529 */
530 public boolean hasWrappers() {
531 return unwrap() != this;
532 }
533
534 /**
535 * Erases all reference types to {@code Object}.
536 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
537 * All primitive types (including {@code void}) will remain unchanged.
538 * @return a version of the original type with all reference types replaced
539 */
540 public MethodType erase() {
541 return form.erasedType();
542 }
543
544 /**
545 * Erases all reference types to {@code Object}, and all subword types to {@code int}.
546 * This is the reduced type polymorphism used by private methods
547 * such as {@link MethodHandle#invokeBasic invokeBasic}.
548 * @return a version of the original type with all reference and subword types replaced
549 */
550 /*non-public*/ MethodType basicType() {
551 return form.basicType();
552 }
553
554 /**
555 * @return a version of the original type with MethodHandle prepended as the first argument
556 */
557 /*non-public*/ MethodType invokerType() {
558 return insertParameterTypes(0, MethodHandle.class);
559 }
560
561 /**
562 * Converts all types, both reference and primitive, to {@code Object}.
563 * Convenience method for {@link #genericMethodType(int) genericMethodType}.
564 * The expression {@code type.wrap().erase()} produces the same value
565 * as {@code type.generic()}.
566 * @return a version of the original type with all types replaced
567 */
568 public MethodType generic() {
569 return genericMethodType(parameterCount());
570 }
571
572 /**
573 * Converts all primitive types to their corresponding wrapper types.
574 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
575 * All reference types (including wrapper types) will remain unchanged.
576 * A {@code void} return type is changed to the type {@code java.lang.Void}.
577 * The expression {@code type.wrap().erase()} produces the same value
578 * as {@code type.generic()}.
579 * @return a version of the original type with all primitive types replaced
580 */
581 public MethodType wrap() {
582 return hasPrimitives() ? wrapWithPrims(this) : this;
583 }
584
585 /**
586 * Converts all wrapper types to their corresponding primitive types.
587 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
588 * All primitive types (including {@code void}) will remain unchanged.
589 * A return type of {@code java.lang.Void} is changed to {@code void}.
590 * @return a version of the original type with all wrapper types replaced
591 */
592 public MethodType unwrap() {
593 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this);
594 return unwrapWithNoPrims(noprims);
595 }
596
597 private static MethodType wrapWithPrims(MethodType pt) {
598 assert(pt.hasPrimitives());
599 MethodType wt = pt.wrapAlt;
600 if (wt == null) {
601 // fill in lazily
602 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP, MethodTypeForm.WRAP);
603 assert(wt != null);
604 pt.wrapAlt = wt;
605 }
606 return wt;
607 }
608
609 private static MethodType unwrapWithNoPrims(MethodType wt) {
610 assert(!wt.hasPrimitives());
611 MethodType uwt = wt.wrapAlt;
612 if (uwt == null) {
613 // fill in lazily
614 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP, MethodTypeForm.UNWRAP);
615 if (uwt == null)
616 uwt = wt; // type has no wrappers or prims at all
617 wt.wrapAlt = uwt;
618 }
619 return uwt;
620 }
621
622 /**
623 * Returns the parameter type at the specified index, within this method type.
624 * @param num the index (zero-based) of the desired parameter type
625 * @return the selected parameter type
626 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
627 */
628 public Class<?> parameterType(int num) {
629 return ptypes[num];
630 }
631 /**
632 * Returns the number of parameter types in this method type.
633 * @return the number of parameter types
634 */
635 public int parameterCount() {
636 return ptypes.length;
637 }
638 /**
639 * Returns the return type of this method type.
640 * @return the return type
641 */
642 public Class<?> returnType() {
643 return rtype;
644 }
645
646 /**
647 * Presents the parameter types as a list (a convenience method).
648 * The list will be immutable.
649 * @return the parameter types (as an immutable list)
650 */
651 public List<Class<?>> parameterList() {
652 return Collections.unmodifiableList(Arrays.asList(ptypes));
653 }
654
655 /*non-public*/ Class<?> lastParameterType() {
656 int len = ptypes.length;
657 return len == 0 ? void.class : ptypes[len-1];
658 }
659
660 /**
661 * Presents the parameter types as an array (a convenience method).
662 * Changes to the array will not result in changes to the type.
663 * @return the parameter types (as a fresh copy if necessary)
664 */
665 public Class<?>[] parameterArray() {
666 return ptypes.clone();
667 }
668
669 /**
670 * Compares the specified object with this type for equality.
671 * That is, it returns <tt>true</tt> if and only if the specified object
672 * is also a method type with exactly the same parameters and return type.
673 * @param x object to compare
674 * @see Object#equals(Object)
675 */
676 @Override
677 public boolean equals(Object x) {
678 return this == x || x instanceof MethodType && equals((MethodType)x);
679 }
680
681 private boolean equals(MethodType that) {
682 return this.rtype == that.rtype
683 && Arrays.equals(this.ptypes, that.ptypes);
684 }
685
686 /**
687 * Returns the hash code value for this method type.
688 * It is defined to be the same as the hashcode of a List
689 * whose elements are the return type followed by the
690 * parameter types.
691 * @return the hash code value for this method type
692 * @see Object#hashCode()
693 * @see #equals(Object)
694 * @see List#hashCode()
695 */
696 @Override
697 public int hashCode() {
698 int hashCode = 31 + rtype.hashCode();
699 for (Class<?> ptype : ptypes)
700 hashCode = 31*hashCode + ptype.hashCode();
701 return hashCode;
702 }
703
704 /**
705 * Returns a string representation of the method type,
706 * of the form {@code "(PT0,PT1...)RT"}.
707 * The string representation of a method type is a
708 * parenthesis enclosed, comma separated list of type names,
709 * followed immediately by the return type.
710 * <p>
711 * Each type is represented by its
712 * {@link java.lang.Class#getSimpleName simple name}.
713 */
714 @Override
715 public String toString() {
716 StringBuilder sb = new StringBuilder();
717 sb.append("(");
718 for (int i = 0; i < ptypes.length; i++) {
719 if (i > 0) sb.append(",");
720 sb.append(ptypes[i].getSimpleName());
721 }
722 sb.append(")");
723 sb.append(rtype.getSimpleName());
724 return sb.toString();
725 }
726
727
728 /*non-public*/
729 boolean isViewableAs(MethodType newType) {
730 if (!VerifyType.isNullConversion(returnType(), newType.returnType()))
731 return false;
732 int argc = parameterCount();
733 if (argc != newType.parameterCount())
734 return false;
735 for (int i = 0; i < argc; i++) {
736 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i)))
737 return false;
738 }
739 return true;
740 }
741 /*non-public*/
742 boolean isCastableTo(MethodType newType) {
743 int argc = parameterCount();
744 if (argc != newType.parameterCount())
745 return false;
746 return true;
747 }
748 /*non-public*/
749 boolean isConvertibleTo(MethodType newType) {
750 if (!canConvert(returnType(), newType.returnType()))
751 return false;
752 int argc = parameterCount();
753 if (argc != newType.parameterCount())
754 return false;
755 for (int i = 0; i < argc; i++) {
756 if (!canConvert(newType.parameterType(i), parameterType(i)))
757 return false;
758 }
759 return true;
760 }
761 /*non-public*/
762 static boolean canConvert(Class<?> src, Class<?> dst) {
763 // short-circuit a few cases:
764 if (src == dst || dst == Object.class) return true;
765 // the remainder of this logic is documented in MethodHandle.asType
766 if (src.isPrimitive()) {
767 // can force void to an explicit null, a la reflect.Method.invoke
768 // can also force void to a primitive zero, by analogy
769 if (src == void.class) return true; //or !dst.isPrimitive()?
770 Wrapper sw = Wrapper.forPrimitiveType(src);
771 if (dst.isPrimitive()) {
772 // P->P must widen
773 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw);
774 } else {
775 // P->R must box and widen
776 return dst.isAssignableFrom(sw.wrapperType());
777 }
778 } else if (dst.isPrimitive()) {
779 // any value can be dropped
780 if (dst == void.class) return true;
781 Wrapper dw = Wrapper.forPrimitiveType(dst);
782 // R->P must be able to unbox (from a dynamically chosen type) and widen
783 // For example:
784 // Byte/Number/Comparable/Object -> dw:Byte -> byte.
785 // Character/Comparable/Object -> dw:Character -> char
786 // Boolean/Comparable/Object -> dw:Boolean -> boolean
787 // This means that dw must be cast-compatible with src.
788 if (src.isAssignableFrom(dw.wrapperType())) {
789 return true;
790 }
791 // The above does not work if the source reference is strongly typed
792 // to a wrapper whose primitive must be widened. For example:
793 // Byte -> unbox:byte -> short/int/long/float/double
794 // Character -> unbox:char -> int/long/float/double
795 if (Wrapper.isWrapperType(src) &&
796 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) {
797 // can unbox from src and then widen to dst
798 return true;
799 }
800 // We have already covered cases which arise due to runtime unboxing
801 // of a reference type which covers several wrapper types:
802 // Object -> cast:Integer -> unbox:int -> long/float/double
803 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double
804 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a
805 // subclass of Number which wraps a value that can convert to char.
806 // Since there is none, we don't need an extra check here to cover char or boolean.
807 return false;
808 } else {
809 // R->R always works, since null is always valid dynamically
810 return true;
811 }
812 }
813
814 /// Queries which have to do with the bytecode architecture
815
816 /** Reports the number of JVM stack slots required to invoke a method
817 * of this type. Note that (for historical reasons) the JVM requires
818 * a second stack slot to pass long and double arguments.
819 * So this method returns {@link #parameterCount() parameterCount} plus the
820 * number of long and double parameters (if any).
821 * <p>
822 * This method is included for the benfit of applications that must
823 * generate bytecodes that process method handles and invokedynamic.
824 * @return the number of JVM stack slots for this type's parameters
825 */
826 /*non-public*/ int parameterSlotCount() {
827 return form.parameterSlotCount();
828 }
829
830 /*non-public*/ Invokers invokers() {
831 Invokers inv = invokers;
832 if (inv != null) return inv;
833 invokers = inv = new Invokers(this);
834 return inv;
835 }
836
837 /** Reports the number of JVM stack slots which carry all parameters including and after
838 * the given position, which must be in the range of 0 to
839 * {@code parameterCount} inclusive. Successive parameters are
840 * more shallowly stacked, and parameters are indexed in the bytecodes
841 * according to their trailing edge. Thus, to obtain the depth
842 * in the outgoing call stack of parameter {@code N}, obtain
843 * the {@code parameterSlotDepth} of its trailing edge
844 * at position {@code N+1}.
845 * <p>
846 * Parameters of type {@code long} and {@code double} occupy
847 * two stack slots (for historical reasons) and all others occupy one.
848 * Therefore, the number returned is the number of arguments
849 * <em>including</em> and <em>after</em> the given parameter,
850 * <em>plus</em> the number of long or double arguments
851 * at or after after the argument for the given parameter.
852 * <p>
853 * This method is included for the benfit of applications that must
854 * generate bytecodes that process method handles and invokedynamic.
855 * @param num an index (zero-based, inclusive) within the parameter types
856 * @return the index of the (shallowest) JVM stack slot transmitting the
857 * given parameter
858 * @throws IllegalArgumentException if {@code num} is negative or greater than {@code parameterCount()}
859 */
860 /*non-public*/ int parameterSlotDepth(int num) {
861 if (num < 0 || num > ptypes.length)
862 parameterType(num); // force a range check
863 return form.parameterToArgSlot(num-1);
864 }
865
866 /** Reports the number of JVM stack slots required to receive a return value
867 * from a method of this type.
868 * If the {@link #returnType() return type} is void, it will be zero,
869 * else if the return type is long or double, it will be two, else one.
870 * <p>
871 * This method is included for the benfit of applications that must
872 * generate bytecodes that process method handles and invokedynamic.
873 * @return the number of JVM stack slots (0, 1, or 2) for this type's return value
874 * Will be removed for PFD.
875 */
876 /*non-public*/ int returnSlotCount() {
877 return form.returnSlotCount();
878 }
879
880 /**
881 * Finds or creates an instance of a method type, given the spelling of its bytecode descriptor.
882 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
883 * Any class or interface name embedded in the descriptor string
884 * will be resolved by calling {@link ClassLoader#loadClass(java.lang.String)}
885 * on the given loader (or if it is null, on the system class loader).
886 * <p>
887 * Note that it is possible to encounter method types which cannot be
888 * constructed by this method, because their component types are
889 * not all reachable from a common class loader.
890 * <p>
891 * This method is included for the benfit of applications that must
892 * generate bytecodes that process method handles and {@code invokedynamic}.
893 * @param descriptor a bytecode-level type descriptor string "(T...)T"
894 * @param loader the class loader in which to look up the types
895 * @return a method type matching the bytecode-level type descriptor
896 * @throws NullPointerException if the string is null
897 * @throws IllegalArgumentException if the string is not well-formed
898 * @throws TypeNotPresentException if a named type cannot be found
899 */
900 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader)
901 throws IllegalArgumentException, TypeNotPresentException
902 {
903 if (!descriptor.startsWith("(") || // also generates NPE if needed
904 descriptor.indexOf(')') < 0 ||
905 descriptor.indexOf('.') >= 0)
906 throw new IllegalArgumentException("not a method descriptor: "+descriptor);
907 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader);
908 Class<?> rtype = types.remove(types.size() - 1);
909 checkSlotCount(types.size());
910 Class<?>[] ptypes = listToArray(types);
911 return makeImpl(rtype, ptypes, true);
912 }
913
914 /**
915 * Produces a bytecode descriptor representation of the method type.
916 * <p>
917 * Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}.
918 * Two distinct classes which share a common name but have different class loaders
919 * will appear identical when viewed within descriptor strings.
920 * <p>
921 * This method is included for the benfit of applications that must
922 * generate bytecodes that process method handles and {@code invokedynamic}.
923 * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString},
924 * because the latter requires a suitable class loader argument.
925 * @return the bytecode type descriptor representation
926 */
927 public String toMethodDescriptorString() {
928 String desc = methodDescriptor;
929 if (desc == null) {
930 desc = BytecodeDescriptor.unparse(this);
931 methodDescriptor = desc;
932 }
933 return desc;
934 }
935
936 /*non-public*/ static String toFieldDescriptorString(Class<?> cls) {
937 return BytecodeDescriptor.unparse(cls);
938 }
939
940 /// Serialization.
941
942 /**
943 * There are no serializable fields for {@code MethodType}.
944 */
945 private static final java.io.ObjectStreamField[] serialPersistentFields = { };
946
947 /**
948 * Save the {@code MethodType} instance to a stream.
949 *
950 * @serialData
951 * For portability, the serialized format does not refer to named fields.
952 * Instead, the return type and parameter type arrays are written directly
953 * from the {@code writeObject} method, using two calls to {@code s.writeObject}
954 * as follows:
955 * <blockquote><pre>
956 s.writeObject(this.returnType());
957 s.writeObject(this.parameterArray());
958 * </pre></blockquote>
959 * <p>
960 * The deserialized field values are checked as if they were
961 * provided to the factory method {@link #methodType(Class,Class[]) methodType}.
962 * For example, null values, or {@code void} parameter types,
963 * will lead to exceptions during deserialization.
964 * @param s the stream to write the object to
965 * @throws java.io.IOException if there is a problem writing the object
966 */
967 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
968 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array
969 s.writeObject(returnType());
970 s.writeObject(parameterArray());
971 }
972
973 /**
974 * Reconstitute the {@code MethodType} instance from a stream (that is,
975 * deserialize it).
976 * This instance is a scratch object with bogus final fields.
977 * It provides the parameters to the factory method called by
978 * {@link #readResolve readResolve}.
979 * After that call it is discarded.
980 * @param s the stream to read the object from
981 * @throws java.io.IOException if there is a problem reading the object
982 * @throws ClassNotFoundException if one of the component classes cannot be resolved
983 * @see #MethodType()
984 * @see #readResolve
985 * @see #writeObject
986 */
987 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
988 s.defaultReadObject(); // requires serialPersistentFields to be an empty array
989
990 Class<?> returnType = (Class<?>) s.readObject();
991 Class<?>[] parameterArray = (Class<?>[]) s.readObject();
992
993 // Probably this object will never escape, but let's check
994 // the field values now, just to be sure.
995 checkRtype(returnType);
996 checkPtypes(parameterArray);
997
998 parameterArray = parameterArray.clone(); // make sure it is unshared
999 MethodType_init(returnType, parameterArray);
1000 }
1001
1002 /**
1003 * For serialization only.
1004 * Sets the final fields to null, pending {@code Unsafe.putObject}.
1005 */
1006 private MethodType() {
1007 this.rtype = null;
1008 this.ptypes = null;
1009 }
1010 private void MethodType_init(Class<?> rtype, Class<?>[] ptypes) {
1011 // In order to communicate these values to readResolve, we must
1012 // store them into the implementation-specific final fields.
1013 checkRtype(rtype);
1014 checkPtypes(ptypes);
1015 UNSAFE.putObject(this, rtypeOffset, rtype);
1016 UNSAFE.putObject(this, ptypesOffset, ptypes);
1017 }
1018
1019 // Support for resetting final fields while deserializing
1020 private static final long rtypeOffset, ptypesOffset;
1021 static {
1022 try {
1023 rtypeOffset = UNSAFE.objectFieldOffset
1024 (MethodType.class.getDeclaredField("rtype"));
1025 ptypesOffset = UNSAFE.objectFieldOffset
1026 (MethodType.class.getDeclaredField("ptypes"));
1027 } catch (Exception ex) {
1028 throw new Error(ex);
1029 }
1030 }
1031
1032 /**
1033 * Resolves and initializes a {@code MethodType} object
1034 * after serialization.
1035 * @return the fully initialized {@code MethodType} object
1036 */
1037 private Object readResolve() {
1038 // Do not use a trusted path for deserialization:
1039 //return makeImpl(rtype, ptypes, true);
1040 // Verify all operands, and make sure ptypes is unshared:
1041 return methodType(rtype, ptypes);
1042 }
1043
1044 /**
1045 * Simple implementation of weak concurrent intern set.
1046 *
1047 * @param <T> interned type
1048 */
1049 private static class ConcurrentWeakInternSet<T> {
1050
1051 private final ConcurrentMap<WeakEntry<T>, WeakEntry<T>> map;
1052 private final ReferenceQueue<T> stale;
1053
1054 public ConcurrentWeakInternSet() {
1055 this.map = new ConcurrentHashMap<>();
1056 this.stale = new ReferenceQueue<>();
1057 }
1058
1059 /**
1060 * Get the existing interned element.
1061 * This method returns null if no element is interned.
1062 *
1063 * @param elem element to look up
1064 * @return the interned element
1065 */
1066 public T get(T elem) {
1067 if (elem == null) throw new NullPointerException();
1068 expungeStaleElements();
1069
1070 WeakEntry<T> value = map.get(new WeakEntry<>(elem));
1071 if (value != null) {
1072 T res = value.get();
1073 if (res != null) {
1074 return res;
1075 }
1076 }
1077 return null;
1078 }
1079
1080 /**
1081 * Interns the element.
1082 * Always returns non-null element, matching the one in the intern set.
1083 * Under the race against another add(), it can return <i>different</i>
1084 * element, if another thread beats us to interning it.
1085 *
1086 * @param elem element to add
1087 * @return element that was actually added
1088 */
1089 public T add(T elem) {
1090 if (elem == null) throw new NullPointerException();
1091
1092 // Playing double race here, and so spinloop is required.
1093 // First race is with two concurrent updaters.
1094 // Second race is with GC purging weak ref under our feet.
1095 // Hopefully, we almost always end up with a single pass.
1096 T interned;
1097 WeakEntry<T> e = new WeakEntry<>(elem, stale);
1098 do {
1099 expungeStaleElements();
1100 WeakEntry<T> exist = map.putIfAbsent(e, e);
1101 interned = (exist == null) ? elem : exist.get();
1102 } while (interned == null);
1103 return interned;
1104 }
1105
1106 private void expungeStaleElements() {
1107 Reference<? extends T> reference;
1108 while ((reference = stale.poll()) != null) {
1109 map.remove(reference);
1110 }
1111 }
1112
1113 private static class WeakEntry<T> extends WeakReference<T> {
1114
1115 public final int hashcode;
1116
1117 public WeakEntry(T key, ReferenceQueue<T> queue) {
1118 super(key, queue);
1119 hashcode = key.hashCode();
1120 }
1121
1122 public WeakEntry(T key) {
1123 super(key);
1124 hashcode = key.hashCode();
1125 }
1126
1127 @Override
1128 public boolean equals(Object obj) {
1129 if (obj instanceof WeakEntry) {
1130 Object that = ((WeakEntry) obj).get();
1131 Object mine = get();
1132 return (that == null || mine == null) ? (this == obj) : mine.equals(that);
1133 }
1134 return false;
1135 }
1136
1137 @Override
1138 public int hashCode() {
1139 return hashcode;
1140 }
1141
1142 }
1143 }
1144
1145 }