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.concurrent.ConcurrentMap;
36 import java.util.concurrent.ConcurrentHashMap;
37 import sun.invoke.util.BytecodeDescriptor;
38 import static java.lang.invoke.MethodHandleStatics.*;
39 import sun.invoke.util.VerifyType;
40
41 /**
42 * A method type represents the arguments and return type accepted and
43 * returned by a method handle, or the arguments and return type passed
44 * and expected by a method handle caller. Method types must be properly
45 * matched between a method handle and all its callers,
46 * and the JVM's operations enforce this matching at, specifically
47 * during calls to {@link MethodHandle#invokeExact MethodHandle.invokeExact}
48 * and {@link MethodHandle#invoke MethodHandle.invoke}, and during execution
49 * of {@code invokedynamic} instructions.
50 * <p>
51 * The structure is a return type accompanied by any number of parameter types.
52 * The types (primitive, {@code void}, and reference) are represented by {@link Class} objects.
53 * (For ease of exposition, we treat {@code void} as if it were a type.
54 * In fact, it denotes the absence of a return type.)
55 * <p>
56 * All instances of {@code MethodType} are immutable.
57 * Two instances are completely interchangeable if they compare equal.
58 * Equality depends on pairwise correspondence of the return and parameter types and on nothing else.
59 * <p>
60 * This type can be created only by factory methods.
61 * All factory methods may cache values, though caching is not guaranteed.
62 * Some factory methods are static, while others are virtual methods which
63 * modify precursor method types, e.g., by changing a selected parameter.
64 * <p>
65 * Factory methods which operate on groups of parameter types
66 * are systematically presented in two versions, so that both Java arrays and
67 * Java lists can be used to work with groups of parameter types.
68 * The query methods {@code parameterArray} and {@code parameterList}
69 * also provide a choice between arrays and lists.
70 * <p>
71 * {@code MethodType} objects are sometimes derived from bytecode instructions
72 * such as {@code invokedynamic}, specifically from the type descriptor strings associated
73 * with the instructions in a class file's constant pool.
74 * <p>
75 * Like classes and strings, method types can also be represented directly
76 * in a class file's constant pool as constants.
77 * A method type may be loaded by an {@code ldc} instruction which refers
78 * to a suitable {@code CONSTANT_MethodType} constant pool entry.
79 * The entry refers to a {@code CONSTANT_Utf8} spelling for the descriptor string.
80 * For more details, see the <a href="package-summary.html#mtcon">package summary</a>.
81 * <p>
82 * When the JVM materializes a {@code MethodType} from a descriptor string,
83 * all classes named in the descriptor must be accessible, and will be loaded.
84 * (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.)
85 * This loading may occur at any time before the {@code MethodType} object is first derived.
86 * @author John Rose, JSR 292 EG
87 */
88 public final
89 class MethodType implements java.io.Serializable {
90 private static final long serialVersionUID = 292L; // {rtype, {ptype...}}
91
92 // The rtype and ptypes fields define the structural identity of the method type:
93 private final Class<?> rtype;
94 private final Class<?>[] ptypes;
95
96 // The remaining fields are caches of various sorts:
97 private MethodTypeForm form; // erased form, plus cached data about primitives
98 private MethodType wrapAlt; // alternative wrapped/unwrapped version
99 private Invokers invokers; // cache of handy higher-order adapters
100
101 /**
102 * Check the given parameters for validity and store them into the final fields.
103 */
104 private MethodType(Class<?> rtype, Class<?>[] ptypes) {
105 checkRtype(rtype);
106 checkPtypes(ptypes);
107 this.rtype = rtype;
108 this.ptypes = ptypes;
109 }
110
111 /*trusted*/ MethodTypeForm form() { return form; }
112 /*trusted*/ Class<?> rtype() { return rtype; }
113 /*trusted*/ Class<?>[] ptypes() { return ptypes; }
114
115 void setForm(MethodTypeForm f) { form = f; }
116
117 /** This number, mandated by the JVM spec as 255,
118 * is the maximum number of <em>slots</em>
119 * that any Java method can receive in its argument list.
120 * It limits both JVM signatures and method type objects.
121 * The longest possible invocation will look like
122 * {@code staticMethod(arg1, arg2, ..., arg255)} or
123 * {@code x.virtualMethod(arg1, arg2, ..., arg254)}.
124 */
125 /*non-public*/ static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec.
126
127 /** This number is the maximum arity of a method handle, 254.
128 * It is derived from the absolute JVM-imposed arity by subtracting one,
129 * which is the slot occupied by the method handle itself at the
130 * beginning of the argument list used to invoke the method handle.
131 * The longest possible invocation will look like
132 * {@code mh.invoke(arg1, arg2, ..., arg254)}.
133 */
134 // Issue: Should we allow MH.invokeWithArguments to go to the full 255?
135 /*non-public*/ static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver
136
137 /** This number is the maximum arity of a method handle invoker, 253.
138 * It is derived from the absolute JVM-imposed arity by subtracting two,
139 * which are the slots occupied by invoke method handle, and the the
140 * target method handle, which are both at the beginning of the argument
141 * list used to invoke the target method handle.
142 * The longest possible invocation will look like
143 * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}.
144 */
145 /*non-public*/ static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker
146
147 private static void checkRtype(Class<?> rtype) {
148 rtype.equals(rtype); // null check
149 }
150 private static int checkPtype(Class<?> ptype) {
151 ptype.getClass(); //NPE
152 if (ptype == void.class)
153 throw newIllegalArgumentException("parameter type cannot be void");
154 if (ptype == double.class || ptype == long.class) return 1;
155 return 0;
156 }
157 /** Return number of extra slots (count of long/double args). */
158 private static int checkPtypes(Class<?>[] ptypes) {
159 int slots = 0;
160 for (Class<?> ptype : ptypes) {
161 slots += checkPtype(ptype);
162 }
163 checkSlotCount(ptypes.length + slots);
164 return slots;
165 }
166 static void checkSlotCount(int count) {
167 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0);
168 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work:
169 if ((count & MAX_JVM_ARITY) != count)
170 throw newIllegalArgumentException("bad parameter count "+count);
171 }
172 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) {
173 if (num instanceof Integer) num = "bad index: "+num;
174 return new IndexOutOfBoundsException(num.toString());
175 }
176
177 static final ConcurrentWeakInternSet<MethodType> internTable = new ConcurrentWeakInternSet<>();
178
179 static final Class<?>[] NO_PTYPES = {};
180
181 /**
182 * Finds or creates an instance of the given method type.
183 * @param rtype the return type
184 * @param ptypes the parameter types
185 * @return a method type with the given components
186 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
187 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
188 */
189 public static
190 MethodType methodType(Class<?> rtype, Class<?>[] ptypes) {
191 return makeImpl(rtype, ptypes, false);
192 }
193
194 /**
195 * Finds or creates a method type with the given components.
196 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
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, List<Class<?>> ptypes) {
203 boolean notrust = false; // random List impl. could return evil ptypes array
204 return makeImpl(rtype, listToArray(ptypes), notrust);
205 }
206
207 private static Class<?>[] listToArray(List<Class<?>> ptypes) {
208 // sanity check the size before the toArray call, since size might be huge
209 checkSlotCount(ptypes.size());
210 return ptypes.toArray(NO_PTYPES);
211 }
212
213 /**
214 * Finds or creates a method type with the given components.
215 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
216 * The leading parameter type is prepended to the remaining array.
217 * @return a method type with the given components
218 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null
219 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class}
220 */
221 public static
222 MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) {
223 Class<?>[] ptypes1 = new Class<?>[1+ptypes.length];
224 ptypes1[0] = ptype0;
225 System.arraycopy(ptypes, 0, ptypes1, 1, ptypes.length);
226 return makeImpl(rtype, ptypes1, true);
227 }
228
229 /**
230 * Finds or creates a method type with the given components.
231 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
232 * The resulting method has no parameter types.
233 * @return a method type with the given return value
234 * @throws NullPointerException if {@code rtype} is null
235 */
236 public static
237 MethodType methodType(Class<?> rtype) {
238 return makeImpl(rtype, NO_PTYPES, true);
239 }
240
241 /**
242 * Finds or creates a method type with the given components.
243 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
244 * The resulting method has the single given parameter type.
245 * @return a method type with the given return value and parameter type
246 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null
247 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class}
248 */
249 public static
250 MethodType methodType(Class<?> rtype, Class<?> ptype0) {
251 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true);
252 }
253
254 /**
255 * Finds or creates a method type with the given components.
256 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
257 * The resulting method has the same parameter types as {@code ptypes},
258 * and the specified return type.
259 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null
260 */
261 public static
262 MethodType methodType(Class<?> rtype, MethodType ptypes) {
263 return makeImpl(rtype, ptypes.ptypes, true);
264 }
265
266 /**
267 * Sole factory method to find or create an interned method type.
268 * @param rtype desired return type
269 * @param ptypes desired parameter types
270 * @param trusted whether the ptypes can be used without cloning
271 * @return the unique method type of the desired structure
272 */
273 /*trusted*/ static
274 MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
275 if (ptypes.length == 0) {
276 ptypes = NO_PTYPES; trusted = true;
277 }
278 MethodType mt1 = new MethodType(rtype, ptypes);
279 MethodType mt0 = internTable.get(mt1);
280 if (mt0 != null)
281 return mt0;
282 if (!trusted)
283 // defensively copy the array passed in by the user
284 mt1 = new MethodType(rtype, ptypes.clone());
285 // promote the object to the Real Thing, and reprobe
286 MethodTypeForm form = MethodTypeForm.findForm(mt1);
287 mt1.form = form;
288 return internTable.add(mt1);
289 }
290 private static final MethodType[] objectOnlyTypes = new MethodType[20];
291
292 /**
293 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array.
294 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
295 * All parameters and the return type will be {@code Object},
296 * except the final array parameter if any, which will be {@code Object[]}.
297 * @param objectArgCount number of parameters (excluding the final array parameter if any)
298 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]}
299 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments
300 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true)
301 * @see #genericMethodType(int)
302 */
303 public static
304 MethodType genericMethodType(int objectArgCount, boolean finalArray) {
305 MethodType mt;
306 checkSlotCount(objectArgCount);
307 int ivarargs = (!finalArray ? 0 : 1);
308 int ootIndex = objectArgCount*2 + ivarargs;
309 if (ootIndex < objectOnlyTypes.length) {
310 mt = objectOnlyTypes[ootIndex];
311 if (mt != null) return mt;
312 }
313 Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs];
314 Arrays.fill(ptypes, Object.class);
315 if (ivarargs != 0) ptypes[objectArgCount] = Object[].class;
316 mt = makeImpl(Object.class, ptypes, true);
317 if (ootIndex < objectOnlyTypes.length) {
318 objectOnlyTypes[ootIndex] = mt; // cache it here also!
319 }
320 return mt;
321 }
322
323 /**
324 * Finds or creates a method type whose components are all {@code Object}.
325 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
326 * All parameters and the return type will be Object.
327 * @param objectArgCount number of parameters
328 * @return a generally applicable method type, for all calls of the given argument count
329 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255
330 * @see #genericMethodType(int, boolean)
331 */
332 public static
333 MethodType genericMethodType(int objectArgCount) {
334 return genericMethodType(objectArgCount, false);
335 }
336
337 /**
338 * Finds or creates a method type with a single different parameter type.
339 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
340 * @param num the index (zero-based) of the parameter type to change
341 * @param nptype a new parameter type to replace the old one with
342 * @return the same type, except with the selected parameter changed
343 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
344 * @throws IllegalArgumentException if {@code nptype} is {@code void.class}
345 * @throws NullPointerException if {@code nptype} is null
346 */
347 public MethodType changeParameterType(int num, Class<?> nptype) {
348 if (parameterType(num) == nptype) return this;
349 checkPtype(nptype);
350 Class<?>[] nptypes = ptypes.clone();
351 nptypes[num] = nptype;
352 return makeImpl(rtype, nptypes, true);
353 }
354
355 /**
356 * Finds or creates a method type with additional parameter types.
357 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
358 * @param num the position (zero-based) of the inserted parameter type(s)
359 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
360 * @return the same type, except with the selected parameter(s) inserted
361 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
362 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
363 * or if the resulting method type would have more than 255 parameter slots
364 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
365 */
366 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) {
367 int len = ptypes.length;
368 if (num < 0 || num > len)
369 throw newIndexOutOfBoundsException(num);
370 int ins = checkPtypes(ptypesToInsert);
371 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins);
372 int ilen = ptypesToInsert.length;
373 if (ilen == 0) return this;
374 Class<?>[] nptypes = Arrays.copyOfRange(ptypes, 0, len+ilen);
375 System.arraycopy(nptypes, num, nptypes, num+ilen, len-num);
376 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen);
377 return makeImpl(rtype, nptypes, true);
378 }
379
380 /**
381 * Finds or creates a method type with additional parameter types.
382 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
383 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
384 * @return the same type, except with the selected parameter(s) appended
385 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
386 * or if the resulting method type would have more than 255 parameter slots
387 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
388 */
389 public MethodType appendParameterTypes(Class<?>... ptypesToInsert) {
390 return insertParameterTypes(parameterCount(), ptypesToInsert);
391 }
392
393 /**
394 * Finds or creates a method type with additional parameter types.
395 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
396 * @param num the position (zero-based) of the inserted parameter type(s)
397 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
398 * @return the same type, except with the selected parameter(s) inserted
399 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
400 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
401 * or if the resulting method type would have more than 255 parameter slots
402 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
403 */
404 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) {
405 return insertParameterTypes(num, listToArray(ptypesToInsert));
406 }
407
408 /**
409 * Finds or creates a method type with additional parameter types.
410 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
411 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
412 * @return the same type, except with the selected parameter(s) appended
413 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
414 * or if the resulting method type would have more than 255 parameter slots
415 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
416 */
417 public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) {
418 return insertParameterTypes(parameterCount(), ptypesToInsert);
419 }
420
421 /**
422 * Finds or creates a method type with modified parameter types.
423 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
424 * @param start the position (zero-based) of the first replaced parameter type(s)
425 * @param end the position (zero-based) after the last replaced parameter type(s)
426 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
427 * @return the same type, except with the selected parameter(s) replaced
428 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
429 * or if {@code end} is negative or greater than {@code parameterCount()}
430 * or if {@code start} is greater than {@code end}
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 /*non-public*/ MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) {
436 if (start == end)
437 return insertParameterTypes(start, ptypesToInsert);
438 int len = ptypes.length;
439 if (!(0 <= start && start <= end && end <= len))
440 throw newIndexOutOfBoundsException("start="+start+" end="+end);
441 int ilen = ptypesToInsert.length;
442 if (ilen == 0)
443 return dropParameterTypes(start, end);
444 return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert);
445 }
446
447 /**
448 * Finds or creates a method type with some parameter types omitted.
449 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
450 * @param start the index (zero-based) of the first parameter type to remove
451 * @param end the index (greater than {@code start}) of the first parameter type after not to remove
452 * @return the same type, except with the selected parameter(s) removed
453 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
454 * or if {@code end} is negative or greater than {@code parameterCount()}
455 * or if {@code start} is greater than {@code end}
456 */
457 public MethodType dropParameterTypes(int start, int end) {
458 int len = ptypes.length;
459 if (!(0 <= start && start <= end && end <= len))
460 throw newIndexOutOfBoundsException("start="+start+" end="+end);
461 if (start == end) return this;
462 Class<?>[] nptypes;
463 if (start == 0) {
464 if (end == len) {
465 // drop all parameters
466 nptypes = NO_PTYPES;
467 } else {
468 // drop initial parameter(s)
469 nptypes = Arrays.copyOfRange(ptypes, end, len);
470 }
471 } else {
472 if (end == len) {
473 // drop trailing parameter(s)
474 nptypes = Arrays.copyOfRange(ptypes, 0, start);
475 } else {
476 int tail = len - end;
477 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail);
478 System.arraycopy(ptypes, end, nptypes, start, tail);
479 }
480 }
481 return makeImpl(rtype, nptypes, true);
482 }
483
484 /**
485 * Finds or creates a method type with a different return type.
486 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
487 * @param nrtype a return parameter type to replace the old one with
488 * @return the same type, except with the return type change
489 * @throws NullPointerException if {@code nrtype} is null
490 */
491 public MethodType changeReturnType(Class<?> nrtype) {
492 if (returnType() == nrtype) return this;
493 return makeImpl(nrtype, ptypes, true);
494 }
495
496 /**
497 * Reports if this type contains a primitive argument or return value.
498 * The return type {@code void} counts as a primitive.
499 * @return true if any of the types are primitives
500 */
501 public boolean hasPrimitives() {
502 return form.hasPrimitives();
503 }
504
505 /**
506 * Reports if this type contains a wrapper argument or return value.
507 * Wrappers are types which box primitive values, such as {@link Integer}.
508 * The reference type {@code java.lang.Void} counts as a wrapper,
509 * if it occurs as a return type.
510 * @return true if any of the types are wrappers
511 */
512 public boolean hasWrappers() {
513 return unwrap() != this;
514 }
515
516 /**
517 * Erases all reference types to {@code Object}.
518 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
519 * All primitive types (including {@code void}) will remain unchanged.
520 * @return a version of the original type with all reference types replaced
521 */
522 public MethodType erase() {
523 return form.erasedType();
524 }
525
526 /**
527 * Erases all reference types to {@code Object}, and all subword types to {@code int}.
528 * This is the reduced type polymorphism used by private methods
529 * such as {@link MethodHandle#invokeBasic invokeBasic}.
530 * @return a version of the original type with all reference and subword types replaced
531 */
532 /*non-public*/ MethodType basicType() {
533 return form.basicType();
534 }
535
536 /**
537 * @return a version of the original type with MethodHandle prepended as the first argument
538 */
539 /*non-public*/ MethodType invokerType() {
540 return insertParameterTypes(0, MethodHandle.class);
541 }
542
543 /**
544 * Converts all types, both reference and primitive, to {@code Object}.
545 * Convenience method for {@link #genericMethodType(int) genericMethodType}.
546 * The expression {@code type.wrap().erase()} produces the same value
547 * as {@code type.generic()}.
548 * @return a version of the original type with all types replaced
549 */
550 public MethodType generic() {
551 return genericMethodType(parameterCount());
552 }
553
554 /**
555 * Converts all primitive types to their corresponding wrapper types.
556 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
557 * All reference types (including wrapper types) will remain unchanged.
558 * A {@code void} return type is changed to the type {@code java.lang.Void}.
559 * The expression {@code type.wrap().erase()} produces the same value
560 * as {@code type.generic()}.
561 * @return a version of the original type with all primitive types replaced
562 */
563 public MethodType wrap() {
564 return hasPrimitives() ? wrapWithPrims(this) : this;
565 }
566
567 /**
568 * Converts all wrapper types to their corresponding primitive types.
569 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
570 * All primitive types (including {@code void}) will remain unchanged.
571 * A return type of {@code java.lang.Void} is changed to {@code void}.
572 * @return a version of the original type with all wrapper types replaced
573 */
574 public MethodType unwrap() {
575 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this);
576 return unwrapWithNoPrims(noprims);
577 }
578
579 private static MethodType wrapWithPrims(MethodType pt) {
580 assert(pt.hasPrimitives());
581 MethodType wt = pt.wrapAlt;
582 if (wt == null) {
583 // fill in lazily
584 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP, MethodTypeForm.WRAP);
585 assert(wt != null);
586 pt.wrapAlt = wt;
587 }
588 return wt;
589 }
590
591 private static MethodType unwrapWithNoPrims(MethodType wt) {
592 assert(!wt.hasPrimitives());
593 MethodType uwt = wt.wrapAlt;
594 if (uwt == null) {
595 // fill in lazily
596 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP, MethodTypeForm.UNWRAP);
597 if (uwt == null)
598 uwt = wt; // type has no wrappers or prims at all
599 wt.wrapAlt = uwt;
600 }
601 return uwt;
602 }
603
604 /**
605 * Returns the parameter type at the specified index, within this method type.
606 * @param num the index (zero-based) of the desired parameter type
607 * @return the selected parameter type
608 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
609 */
610 public Class<?> parameterType(int num) {
611 return ptypes[num];
612 }
613 /**
614 * Returns the number of parameter types in this method type.
615 * @return the number of parameter types
616 */
617 public int parameterCount() {
618 return ptypes.length;
619 }
620 /**
621 * Returns the return type of this method type.
622 * @return the return type
623 */
624 public Class<?> returnType() {
625 return rtype;
626 }
627
628 /**
629 * Presents the parameter types as a list (a convenience method).
630 * The list will be immutable.
631 * @return the parameter types (as an immutable list)
632 */
633 public List<Class<?>> parameterList() {
634 return Collections.unmodifiableList(Arrays.asList(ptypes));
635 }
636
637 /*non-public*/ Class<?> lastParameterType() {
638 int len = ptypes.length;
639 return len == 0 ? void.class : ptypes[len-1];
640 }
641
642 /**
643 * Presents the parameter types as an array (a convenience method).
644 * Changes to the array will not result in changes to the type.
645 * @return the parameter types (as a fresh copy if necessary)
646 */
647 public Class<?>[] parameterArray() {
648 return ptypes.clone();
649 }
650
651 /**
652 * Compares the specified object with this type for equality.
653 * That is, it returns <tt>true</tt> if and only if the specified object
654 * is also a method type with exactly the same parameters and return type.
655 * @param x object to compare
656 * @see Object#equals(Object)
657 */
658 @Override
659 public boolean equals(Object x) {
660 return this == x || x instanceof MethodType && equals((MethodType)x);
661 }
662
663 private boolean equals(MethodType that) {
664 return this.rtype == that.rtype
665 && Arrays.equals(this.ptypes, that.ptypes);
666 }
667
668 /**
669 * Returns the hash code value for this method type.
670 * It is defined to be the same as the hashcode of a List
671 * whose elements are the return type followed by the
672 * parameter types.
673 * @return the hash code value for this method type
674 * @see Object#hashCode()
675 * @see #equals(Object)
676 * @see List#hashCode()
677 */
678 @Override
679 public int hashCode() {
680 int hashCode = 31 + rtype.hashCode();
681 for (Class<?> ptype : ptypes)
682 hashCode = 31*hashCode + ptype.hashCode();
683 return hashCode;
684 }
685
686 /**
687 * Returns a string representation of the method type,
688 * of the form {@code "(PT0,PT1...)RT"}.
689 * The string representation of a method type is a
690 * parenthesis enclosed, comma separated list of type names,
691 * followed immediately by the return type.
692 * <p>
693 * Each type is represented by its
694 * {@link java.lang.Class#getSimpleName simple name}.
695 */
696 @Override
697 public String toString() {
698 StringBuilder sb = new StringBuilder();
699 sb.append("(");
700 for (int i = 0; i < ptypes.length; i++) {
701 if (i > 0) sb.append(",");
702 sb.append(ptypes[i].getSimpleName());
703 }
704 sb.append(")");
705 sb.append(rtype.getSimpleName());
706 return sb.toString();
707 }
708
709
710 /*non-public*/
711 boolean isViewableAs(MethodType newType) {
712 if (!VerifyType.isNullConversion(returnType(), newType.returnType()))
713 return false;
714 int argc = parameterCount();
715 if (argc != newType.parameterCount())
716 return false;
717 for (int i = 0; i < argc; i++) {
718 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i)))
719 return false;
720 }
721 return true;
722 }
723 /*non-public*/
724 boolean isCastableTo(MethodType newType) {
725 int argc = parameterCount();
726 if (argc != newType.parameterCount())
727 return false;
728 return true;
729 }
730 /*non-public*/
731 boolean isConvertibleTo(MethodType newType) {
732 if (!canConvert(returnType(), newType.returnType()))
733 return false;
734 int argc = parameterCount();
735 if (argc != newType.parameterCount())
736 return false;
737 for (int i = 0; i < argc; i++) {
738 if (!canConvert(newType.parameterType(i), parameterType(i)))
739 return false;
740 }
741 return true;
742 }
743 /*non-public*/
744 static boolean canConvert(Class<?> src, Class<?> dst) {
745 // short-circuit a few cases:
746 if (src == dst || dst == Object.class) return true;
747 // the remainder of this logic is documented in MethodHandle.asType
748 if (src.isPrimitive()) {
749 // can force void to an explicit null, a la reflect.Method.invoke
750 // can also force void to a primitive zero, by analogy
751 if (src == void.class) return true; //or !dst.isPrimitive()?
752 Wrapper sw = Wrapper.forPrimitiveType(src);
753 if (dst.isPrimitive()) {
754 // P->P must widen
755 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw);
756 } else {
757 // P->R must box and widen
758 return dst.isAssignableFrom(sw.wrapperType());
759 }
760 } else if (dst.isPrimitive()) {
761 // any value can be dropped
762 if (dst == void.class) return true;
763 Wrapper dw = Wrapper.forPrimitiveType(dst);
764 // R->P must be able to unbox (from a dynamically chosen type) and widen
765 // For example:
766 // Byte/Number/Comparable/Object -> dw:Byte -> byte.
767 // Character/Comparable/Object -> dw:Character -> char
768 // Boolean/Comparable/Object -> dw:Boolean -> boolean
769 // This means that dw must be cast-compatible with src.
770 if (src.isAssignableFrom(dw.wrapperType())) {
771 return true;
772 }
773 // The above does not work if the source reference is strongly typed
774 // to a wrapper whose primitive must be widened. For example:
775 // Byte -> unbox:byte -> short/int/long/float/double
776 // Character -> unbox:char -> int/long/float/double
777 if (Wrapper.isWrapperType(src) &&
778 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) {
779 // can unbox from src and then widen to dst
780 return true;
781 }
782 // We have already covered cases which arise due to runtime unboxing
783 // of a reference type which covers several wrapper types:
784 // Object -> cast:Integer -> unbox:int -> long/float/double
785 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double
786 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a
787 // subclass of Number which wraps a value that can convert to char.
788 // Since there is none, we don't need an extra check here to cover char or boolean.
789 return false;
790 } else {
791 // R->R always works, since null is always valid dynamically
792 return true;
793 }
794 }
795
796 /// Queries which have to do with the bytecode architecture
797
798 /** Reports the number of JVM stack slots required to invoke a method
799 * of this type. Note that (for historical reasons) the JVM requires
800 * a second stack slot to pass long and double arguments.
801 * So this method returns {@link #parameterCount() parameterCount} plus the
802 * number of long and double parameters (if any).
803 * <p>
804 * This method is included for the benfit of applications that must
805 * generate bytecodes that process method handles and invokedynamic.
806 * @return the number of JVM stack slots for this type's parameters
807 */
808 /*non-public*/ int parameterSlotCount() {
809 return form.parameterSlotCount();
810 }
811
812 /*non-public*/ Invokers invokers() {
813 Invokers inv = invokers;
814 if (inv != null) return inv;
815 invokers = inv = new Invokers(this);
816 return inv;
817 }
818
819 /** Reports the number of JVM stack slots which carry all parameters including and after
820 * the given position, which must be in the range of 0 to
821 * {@code parameterCount} inclusive. Successive parameters are
822 * more shallowly stacked, and parameters are indexed in the bytecodes
823 * according to their trailing edge. Thus, to obtain the depth
824 * in the outgoing call stack of parameter {@code N}, obtain
825 * the {@code parameterSlotDepth} of its trailing edge
826 * at position {@code N+1}.
827 * <p>
828 * Parameters of type {@code long} and {@code double} occupy
829 * two stack slots (for historical reasons) and all others occupy one.
830 * Therefore, the number returned is the number of arguments
831 * <em>including</em> and <em>after</em> the given parameter,
832 * <em>plus</em> the number of long or double arguments
833 * at or after after the argument for the given parameter.
834 * <p>
835 * This method is included for the benfit of applications that must
836 * generate bytecodes that process method handles and invokedynamic.
837 * @param num an index (zero-based, inclusive) within the parameter types
838 * @return the index of the (shallowest) JVM stack slot transmitting the
839 * given parameter
840 * @throws IllegalArgumentException if {@code num} is negative or greater than {@code parameterCount()}
841 */
842 /*non-public*/ int parameterSlotDepth(int num) {
843 if (num < 0 || num > ptypes.length)
844 parameterType(num); // force a range check
845 return form.parameterToArgSlot(num-1);
846 }
847
848 /** Reports the number of JVM stack slots required to receive a return value
849 * from a method of this type.
850 * If the {@link #returnType() return type} is void, it will be zero,
851 * else if the return type is long or double, it will be two, else one.
852 * <p>
853 * This method is included for the benfit of applications that must
854 * generate bytecodes that process method handles and invokedynamic.
855 * @return the number of JVM stack slots (0, 1, or 2) for this type's return value
856 * Will be removed for PFD.
857 */
858 /*non-public*/ int returnSlotCount() {
859 return form.returnSlotCount();
860 }
861
862 /**
863 * Finds or creates an instance of a method type, given the spelling of its bytecode descriptor.
864 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
865 * Any class or interface name embedded in the descriptor string
866 * will be resolved by calling {@link ClassLoader#loadClass(java.lang.String)}
867 * on the given loader (or if it is null, on the system class loader).
868 * <p>
869 * Note that it is possible to encounter method types which cannot be
870 * constructed by this method, because their component types are
871 * not all reachable from a common class loader.
872 * <p>
873 * This method is included for the benfit of applications that must
874 * generate bytecodes that process method handles and {@code invokedynamic}.
875 * @param descriptor a bytecode-level type descriptor string "(T...)T"
876 * @param loader the class loader in which to look up the types
877 * @return a method type matching the bytecode-level type descriptor
878 * @throws NullPointerException if the string is null
879 * @throws IllegalArgumentException if the string is not well-formed
880 * @throws TypeNotPresentException if a named type cannot be found
881 */
882 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader)
883 throws IllegalArgumentException, TypeNotPresentException
884 {
885 if (!descriptor.startsWith("(") || // also generates NPE if needed
886 descriptor.indexOf(')') < 0 ||
887 descriptor.indexOf('.') >= 0)
888 throw new IllegalArgumentException("not a method descriptor: "+descriptor);
889 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader);
890 Class<?> rtype = types.remove(types.size() - 1);
891 checkSlotCount(types.size());
892 Class<?>[] ptypes = listToArray(types);
893 return makeImpl(rtype, ptypes, true);
894 }
895
896 /**
897 * Produces a bytecode descriptor representation of the method type.
898 * <p>
899 * Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}.
900 * Two distinct classes which share a common name but have different class loaders
901 * will appear identical when viewed within descriptor strings.
902 * <p>
903 * This method is included for the benfit of applications that must
904 * generate bytecodes that process method handles and {@code invokedynamic}.
905 * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString},
906 * because the latter requires a suitable class loader argument.
907 * @return the bytecode type descriptor representation
908 */
909 public String toMethodDescriptorString() {
910 return BytecodeDescriptor.unparse(this);
911 }
912
913 /*non-public*/ static String toFieldDescriptorString(Class<?> cls) {
914 return BytecodeDescriptor.unparse(cls);
915 }
916
917 /// Serialization.
918
919 /**
920 * There are no serializable fields for {@code MethodType}.
921 */
922 private static final java.io.ObjectStreamField[] serialPersistentFields = { };
923
924 /**
925 * Save the {@code MethodType} instance to a stream.
926 *
927 * @serialData
928 * For portability, the serialized format does not refer to named fields.
929 * Instead, the return type and parameter type arrays are written directly
930 * from the {@code writeObject} method, using two calls to {@code s.writeObject}
931 * as follows:
932 * <blockquote><pre>
933 s.writeObject(this.returnType());
934 s.writeObject(this.parameterArray());
935 * </pre></blockquote>
936 * <p>
937 * The deserialized field values are checked as if they were
938 * provided to the factory method {@link #methodType(Class,Class[]) methodType}.
939 * For example, null values, or {@code void} parameter types,
940 * will lead to exceptions during deserialization.
941 * @param the stream to write the object to
942 */
943 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
944 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array
945 s.writeObject(returnType());
946 s.writeObject(parameterArray());
947 }
948
949 /**
950 * Reconstitute the {@code MethodType} instance from a stream (that is,
951 * deserialize it).
952 * This instance is a scratch object with bogus final fields.
953 * It provides the parameters to the factory method called by
954 * {@link #readResolve readResolve}.
955 * After that call it is discarded.
956 * @param the stream to read the object from
957 * @see #MethodType()
958 * @see #readResolve
959 * @see #writeObject
960 */
961 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
962 s.defaultReadObject(); // requires serialPersistentFields to be an empty array
963
964 Class<?> returnType = (Class<?>) s.readObject();
965 Class<?>[] parameterArray = (Class<?>[]) s.readObject();
966
967 // Probably this object will never escape, but let's check
968 // the field values now, just to be sure.
969 checkRtype(returnType);
970 checkPtypes(parameterArray);
971
972 parameterArray = parameterArray.clone(); // make sure it is unshared
973 MethodType_init(returnType, parameterArray);
974 }
975
976 /**
977 * For serialization only.
978 * Sets the final fields to null, pending {@code Unsafe.putObject}.
979 */
980 private MethodType() {
981 this.rtype = null;
982 this.ptypes = null;
983 }
984 private void MethodType_init(Class<?> rtype, Class<?>[] ptypes) {
985 // In order to communicate these values to readResolve, we must
986 // store them into the implementation-specific final fields.
987 checkRtype(rtype);
988 checkPtypes(ptypes);
989 UNSAFE.putObject(this, rtypeOffset, rtype);
990 UNSAFE.putObject(this, ptypesOffset, ptypes);
991 }
992
993 // Support for resetting final fields while deserializing
994 private static final long rtypeOffset, ptypesOffset;
995 static {
996 try {
997 rtypeOffset = UNSAFE.objectFieldOffset
998 (MethodType.class.getDeclaredField("rtype"));
999 ptypesOffset = UNSAFE.objectFieldOffset
1000 (MethodType.class.getDeclaredField("ptypes"));
1001 } catch (Exception ex) {
1002 throw new Error(ex);
1003 }
1004 }
1005
1006 /**
1007 * Resolves and initializes a {@code MethodType} object
1008 * after serialization.
1009 * @return the fully initialized {@code MethodType} object
1010 */
1011 private Object readResolve() {
1012 // Do not use a trusted path for deserialization:
1013 //return makeImpl(rtype, ptypes, true);
1014 // Verify all operands, and make sure ptypes is unshared:
1015 return methodType(rtype, ptypes);
1016 }
1017
1018 /**
1019 * Simple implementation of weak concurrent intern set.
1020 *
1021 * @param <T> interned type
1022 */
1023 private static class ConcurrentWeakInternSet<T> {
1024
1025 private final ConcurrentMap<WeakEntry<T>, WeakEntry<T>> map;
1026 private final ReferenceQueue<T> stale;
1027
1028 public ConcurrentWeakInternSet() {
1029 this.map = new ConcurrentHashMap<>();
1030 this.stale = new ReferenceQueue<>();
1031 }
1032
1033 /**
1034 * Get the existing interned element.
1035 * This method returns null if no element is interned.
1036 *
1037 * @param elem element to look up
1038 * @return the interned element
1039 */
1040 public T get(T elem) {
1041 if (elem == null) throw new NullPointerException();
1042 expungeStaleElements();
1043
1044 WeakEntry<T> value = map.get(new WeakEntry<>(elem));
1045 if (value != null) {
1046 T res = value.get();
1047 if (res != null) {
1048 return res;
1049 }
1050 }
1051 return null;
1052 }
1053
1054 /**
1055 * Interns the element.
1056 * Always returns non-null element, matching the one in the intern set.
1057 * Under the race against another add(), it can return <i>different</i>
1058 * element, if another thread beats us to interning it.
1059 *
1060 * @param elem element to add
1061 * @return element that was actually added
1062 */
1063 public T add(T elem) {
1064 if (elem == null) throw new NullPointerException();
1065
1066 // Playing double race here, and so spinloop is required.
1067 // First race is with two concurrent updaters.
1068 // Second race is with GC purging weak ref under our feet.
1069 // Hopefully, we almost always end up with a single pass.
1070 T interned;
1071 WeakEntry<T> e = new WeakEntry<>(elem, stale);
1072 do {
1073 expungeStaleElements();
1074 WeakEntry<T> exist = map.putIfAbsent(e, e);
1075 interned = (exist == null) ? elem : exist.get();
1076 } while (interned == null);
1077 return interned;
1078 }
1079
1080 private void expungeStaleElements() {
1081 Reference<? extends T> reference;
1082 while ((reference = stale.poll()) != null) {
1083 map.remove(reference);
1084 }
1085 }
1086
1087 private static class WeakEntry<T> extends WeakReference<T> {
1088
1089 public final int hashcode;
1090
1091 public WeakEntry(T key, ReferenceQueue<T> queue) {
1092 super(key, queue);
1093 hashcode = key.hashCode();
1094 }
1095
1096 public WeakEntry(T key) {
1097 super(key);
1098 hashcode = key.hashCode();
1099 }
1100
1101 @Override
1102 public boolean equals(Object obj) {
1103 if (obj instanceof WeakEntry) {
1104 Object that = ((WeakEntry) obj).get();
1105 Object mine = get();
1106 return (that == null || mine == null) ? (this == obj) : mine.equals(that);
1107 }
1108 return false;
1109 }
1110
1111 @Override
1112 public int hashCode() {
1113 return hashcode;
1114 }
1115
1116 }
1117 }
1118
1119 }