1 /*
2 * Copyright (c) 2008, 2013, 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 full details on method type constants,
82 * see sections 4.4.8 and 5.4.3.5 of the Java Virtual Machine Specification.)
83 * <p>
84 * When the JVM materializes a {@code MethodType} from a descriptor string,
85 * all classes named in the descriptor must be accessible, and will be loaded.
86 * (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.)
87 * This loading may occur at any time before the {@code MethodType} object is first derived.
88 * @author John Rose, JSR 292 EG
89 */
90 public final
91 class MethodType implements java.io.Serializable {
92 private static final long serialVersionUID = 292L; // {rtype, {ptype...}}
93
94 // The rtype and ptypes fields define the structural identity of the method type:
95 private final Class<?> rtype;
96 private final Class<?>[] ptypes;
97
98 // The remaining fields are caches of various sorts:
99 private @Stable MethodTypeForm form; // erased form, plus cached data about primitives
100 private @Stable MethodType wrapAlt; // alternative wrapped/unwrapped version
101 private @Stable Invokers invokers; // cache of handy higher-order adapters
102 private @Stable String methodDescriptor; // cache for toMethodDescriptorString
103
104 /**
105 * Check the given parameters for validity and store them into the final fields.
106 */
107 private MethodType(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
108 checkRtype(rtype);
109 checkPtypes(ptypes);
110 this.rtype = rtype;
111 // defensively copy the array passed in by the user
112 this.ptypes = trusted ? ptypes : Arrays.copyOf(ptypes, ptypes.length);
113 }
114
115 /**
116 * Construct a temporary unchecked instance of MethodType for use only as a key to the intern table.
117 * Does not check the given parameters for validity, and must be discarded after it is used as a searching key.
118 * The parameters are reversed for this constructor, so that is is not accidentally used.
119 */
120 private MethodType(Class<?>[] ptypes, Class<?> rtype) {
121 this.rtype = rtype;
122 this.ptypes = ptypes;
123 }
124
125 /*trusted*/ MethodTypeForm form() { return form; }
126 /*trusted*/ Class<?> rtype() { return rtype; }
127 /*trusted*/ Class<?>[] ptypes() { return ptypes; }
128
129 void setForm(MethodTypeForm f) { form = f; }
130
131 /** This number, mandated by the JVM spec as 255,
132 * is the maximum number of <em>slots</em>
133 * that any Java method can receive in its argument list.
134 * It limits both JVM signatures and method type objects.
135 * The longest possible invocation will look like
136 * {@code staticMethod(arg1, arg2, ..., arg255)} or
137 * {@code x.virtualMethod(arg1, arg2, ..., arg254)}.
138 */
139 /*non-public*/ static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec.
140
141 /** This number is the maximum arity of a method handle, 254.
142 * It is derived from the absolute JVM-imposed arity by subtracting one,
143 * which is the slot occupied by the method handle itself at the
144 * beginning of the argument list used to invoke the method handle.
145 * The longest possible invocation will look like
146 * {@code mh.invoke(arg1, arg2, ..., arg254)}.
147 */
148 // Issue: Should we allow MH.invokeWithArguments to go to the full 255?
149 /*non-public*/ static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver
150
151 /** This number is the maximum arity of a method handle invoker, 253.
152 * It is derived from the absolute JVM-imposed arity by subtracting two,
153 * which are the slots occupied by invoke method handle, and the
154 * target method handle, which are both at the beginning of the argument
155 * list used to invoke the target method handle.
156 * The longest possible invocation will look like
157 * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}.
158 */
159 /*non-public*/ static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker
160
161 private static void checkRtype(Class<?> rtype) {
162 Objects.requireNonNull(rtype);
163 }
164 private static void checkPtype(Class<?> ptype) {
165 Objects.requireNonNull(ptype);
166 if (ptype == void.class)
167 throw newIllegalArgumentException("parameter type cannot be void");
168 }
169 /** Return number of extra slots (count of long/double args). */
170 private static int checkPtypes(Class<?>[] ptypes) {
171 int slots = 0;
172 for (Class<?> ptype : ptypes) {
173 checkPtype(ptype);
174 if (ptype == double.class || ptype == long.class) {
175 slots++;
176 }
177 }
178 checkSlotCount(ptypes.length + slots);
179 return slots;
180 }
181 static void checkSlotCount(int count) {
182 assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0);
183 // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work:
184 if ((count & MAX_JVM_ARITY) != count)
185 throw newIllegalArgumentException("bad parameter count "+count);
186 }
187 private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) {
188 if (num instanceof Integer) num = "bad index: "+num;
189 return new IndexOutOfBoundsException(num.toString());
190 }
191
192 static final ConcurrentWeakInternSet<MethodType> internTable = new ConcurrentWeakInternSet<>();
193
194 static final Class<?>[] NO_PTYPES = {};
195
196 /**
197 * Finds or creates an instance of the given method type.
198 * @param rtype the return type
199 * @param ptypes the parameter types
200 * @return a method type with the given components
201 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
202 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
203 */
204 public static
205 MethodType methodType(Class<?> rtype, Class<?>[] ptypes) {
206 return makeImpl(rtype, ptypes, false);
207 }
208
209 /**
210 * Finds or creates a method type with the given components.
211 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
212 * @param rtype the return type
213 * @param ptypes the parameter types
214 * @return a method type with the given components
215 * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
216 * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
217 */
218 public static
219 MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) {
220 boolean notrust = false; // random List impl. could return evil ptypes array
221 return makeImpl(rtype, listToArray(ptypes), notrust);
222 }
223
224 private static Class<?>[] listToArray(List<Class<?>> ptypes) {
225 // sanity check the size before the toArray call, since size might be huge
226 checkSlotCount(ptypes.size());
227 return ptypes.toArray(NO_PTYPES);
228 }
229
230 /**
231 * Finds or creates a method type with the given components.
232 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
233 * The leading parameter type is prepended to the remaining array.
234 * @param rtype the return type
235 * @param ptype0 the first parameter type
236 * @param ptypes the remaining parameter types
237 * @return a method type with the given components
238 * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null
239 * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class}
240 */
241 public static
242 MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) {
243 Class<?>[] ptypes1 = new Class<?>[1+ptypes.length];
244 ptypes1[0] = ptype0;
245 System.arraycopy(ptypes, 0, ptypes1, 1, ptypes.length);
246 return makeImpl(rtype, ptypes1, true);
247 }
248
249 /**
250 * Finds or creates a method type with the given components.
251 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
252 * The resulting method has no parameter types.
253 * @param rtype the return type
254 * @return a method type with the given return value
255 * @throws NullPointerException if {@code rtype} is null
256 */
257 public static
258 MethodType methodType(Class<?> rtype) {
259 return makeImpl(rtype, NO_PTYPES, true);
260 }
261
262 /**
263 * Finds or creates a method type with the given components.
264 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
265 * The resulting method has the single given parameter type.
266 * @param rtype the return type
267 * @param ptype0 the parameter type
268 * @return a method type with the given return value and parameter type
269 * @throws NullPointerException if {@code rtype} or {@code ptype0} is null
270 * @throws IllegalArgumentException if {@code ptype0} is {@code void.class}
271 */
272 public static
273 MethodType methodType(Class<?> rtype, Class<?> ptype0) {
274 return makeImpl(rtype, new Class<?>[]{ ptype0 }, true);
275 }
276
277 /**
278 * Finds or creates a method type with the given components.
279 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
280 * The resulting method has the same parameter types as {@code ptypes},
281 * and the specified return type.
282 * @param rtype the return type
283 * @param ptypes the method type which supplies the parameter types
284 * @return a method type with the given components
285 * @throws NullPointerException if {@code rtype} or {@code ptypes} is null
286 */
287 public static
288 MethodType methodType(Class<?> rtype, MethodType ptypes) {
289 return makeImpl(rtype, ptypes.ptypes, true);
290 }
291
292 /**
293 * Sole factory method to find or create an interned method type.
294 * @param rtype desired return type
295 * @param ptypes desired parameter types
296 * @param trusted whether the ptypes can be used without cloning
297 * @return the unique method type of the desired structure
298 */
299 /*trusted*/ static
300 MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {
301 MethodType mt = internTable.get(new MethodType(ptypes, rtype));
302 if (mt != null)
303 return mt;
304 if (ptypes.length == 0) {
305 ptypes = NO_PTYPES; trusted = true;
306 }
307 mt = new MethodType(rtype, ptypes, trusted);
308 // promote the object to the Real Thing, and reprobe
309 mt.form = MethodTypeForm.findForm(mt);
310 return internTable.add(mt);
311 }
312 private static final MethodType[] objectOnlyTypes = new MethodType[20];
313
314 /**
315 * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array.
316 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
317 * All parameters and the return type will be {@code Object},
318 * except the final array parameter if any, which will be {@code Object[]}.
319 * @param objectArgCount number of parameters (excluding the final array parameter if any)
320 * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]}
321 * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments
322 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true)
323 * @see #genericMethodType(int)
324 */
325 public static
326 MethodType genericMethodType(int objectArgCount, boolean finalArray) {
327 MethodType mt;
328 checkSlotCount(objectArgCount);
329 int ivarargs = (!finalArray ? 0 : 1);
330 int ootIndex = objectArgCount*2 + ivarargs;
331 if (ootIndex < objectOnlyTypes.length) {
332 mt = objectOnlyTypes[ootIndex];
333 if (mt != null) return mt;
334 }
335 Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs];
336 Arrays.fill(ptypes, Object.class);
337 if (ivarargs != 0) ptypes[objectArgCount] = Object[].class;
338 mt = makeImpl(Object.class, ptypes, true);
339 if (ootIndex < objectOnlyTypes.length) {
340 objectOnlyTypes[ootIndex] = mt; // cache it here also!
341 }
342 return mt;
343 }
344
345 /**
346 * Finds or creates a method type whose components are all {@code Object}.
347 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
348 * All parameters and the return type will be Object.
349 * @param objectArgCount number of parameters
350 * @return a generally applicable method type, for all calls of the given argument count
351 * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255
352 * @see #genericMethodType(int, boolean)
353 */
354 public static
355 MethodType genericMethodType(int objectArgCount) {
356 return genericMethodType(objectArgCount, false);
357 }
358
359 /**
360 * Finds or creates a method type with a single different parameter type.
361 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
362 * @param num the index (zero-based) of the parameter type to change
363 * @param nptype a new parameter type to replace the old one with
364 * @return the same type, except with the selected parameter changed
365 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
366 * @throws IllegalArgumentException if {@code nptype} is {@code void.class}
367 * @throws NullPointerException if {@code nptype} is null
368 */
369 public MethodType changeParameterType(int num, Class<?> nptype) {
370 if (parameterType(num) == nptype) return this;
371 checkPtype(nptype);
372 Class<?>[] nptypes = ptypes.clone();
373 nptypes[num] = nptype;
374 return makeImpl(rtype, nptypes, true);
375 }
376
377 /**
378 * Finds or creates a method type with additional parameter types.
379 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
380 * @param num the position (zero-based) of the inserted parameter type(s)
381 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
382 * @return the same type, except with the selected parameter(s) inserted
383 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
384 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
385 * or if the resulting method type would have more than 255 parameter slots
386 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
387 */
388 public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) {
389 int len = ptypes.length;
390 if (num < 0 || num > len)
391 throw newIndexOutOfBoundsException(num);
392 int ins = checkPtypes(ptypesToInsert);
393 checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins);
394 int ilen = ptypesToInsert.length;
395 if (ilen == 0) return this;
396 Class<?>[] nptypes = Arrays.copyOfRange(ptypes, 0, len+ilen);
397 System.arraycopy(nptypes, num, nptypes, num+ilen, len-num);
398 System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen);
399 return makeImpl(rtype, nptypes, true);
400 }
401
402 /**
403 * Finds or creates a method type with additional parameter types.
404 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
405 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
406 * @return the same type, except with the selected parameter(s) appended
407 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
408 * or if the resulting method type would have more than 255 parameter slots
409 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
410 */
411 public MethodType appendParameterTypes(Class<?>... ptypesToInsert) {
412 return insertParameterTypes(parameterCount(), ptypesToInsert);
413 }
414
415 /**
416 * Finds or creates a method type with additional parameter types.
417 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
418 * @param num the position (zero-based) of the inserted parameter type(s)
419 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
420 * @return the same type, except with the selected parameter(s) inserted
421 * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
422 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
423 * or if the resulting method type would have more than 255 parameter slots
424 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
425 */
426 public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) {
427 return insertParameterTypes(num, listToArray(ptypesToInsert));
428 }
429
430 /**
431 * Finds or creates a method type with additional parameter types.
432 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
433 * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
434 * @return the same type, except with the selected parameter(s) appended
435 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
436 * or if the resulting method type would have more than 255 parameter slots
437 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
438 */
439 public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) {
440 return insertParameterTypes(parameterCount(), ptypesToInsert);
441 }
442
443 /**
444 * Finds or creates a method type with modified parameter types.
445 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
446 * @param start the position (zero-based) of the first replaced parameter type(s)
447 * @param end the position (zero-based) after the last replaced parameter type(s)
448 * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
449 * @return the same type, except with the selected parameter(s) replaced
450 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
451 * or if {@code end} is negative or greater than {@code parameterCount()}
452 * or if {@code start} is greater than {@code end}
453 * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
454 * or if the resulting method type would have more than 255 parameter slots
455 * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
456 */
457 /*non-public*/ MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) {
458 if (start == end)
459 return insertParameterTypes(start, ptypesToInsert);
460 int len = ptypes.length;
461 if (!(0 <= start && start <= end && end <= len))
462 throw newIndexOutOfBoundsException("start="+start+" end="+end);
463 int ilen = ptypesToInsert.length;
464 if (ilen == 0)
465 return dropParameterTypes(start, end);
466 return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert);
467 }
468
469 /**
470 * Finds or creates a method type with some parameter types omitted.
471 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
472 * @param start the index (zero-based) of the first parameter type to remove
473 * @param end the index (greater than {@code start}) of the first parameter type after not to remove
474 * @return the same type, except with the selected parameter(s) removed
475 * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
476 * or if {@code end} is negative or greater than {@code parameterCount()}
477 * or if {@code start} is greater than {@code end}
478 */
479 public MethodType dropParameterTypes(int start, int end) {
480 int len = ptypes.length;
481 if (!(0 <= start && start <= end && end <= len))
482 throw newIndexOutOfBoundsException("start="+start+" end="+end);
483 if (start == end) return this;
484 Class<?>[] nptypes;
485 if (start == 0) {
486 if (end == len) {
487 // drop all parameters
488 nptypes = NO_PTYPES;
489 } else {
490 // drop initial parameter(s)
491 nptypes = Arrays.copyOfRange(ptypes, end, len);
492 }
493 } else {
494 if (end == len) {
495 // drop trailing parameter(s)
496 nptypes = Arrays.copyOfRange(ptypes, 0, start);
497 } else {
498 int tail = len - end;
499 nptypes = Arrays.copyOfRange(ptypes, 0, start + tail);
500 System.arraycopy(ptypes, end, nptypes, start, tail);
501 }
502 }
503 return makeImpl(rtype, nptypes, true);
504 }
505
506 /**
507 * Finds or creates a method type with a different return type.
508 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
509 * @param nrtype a return parameter type to replace the old one with
510 * @return the same type, except with the return type change
511 * @throws NullPointerException if {@code nrtype} is null
512 */
513 public MethodType changeReturnType(Class<?> nrtype) {
514 if (returnType() == nrtype) return this;
515 return makeImpl(nrtype, ptypes, true);
516 }
517
518 /**
519 * Reports if this type contains a primitive argument or return value.
520 * The return type {@code void} counts as a primitive.
521 * @return true if any of the types are primitives
522 */
523 public boolean hasPrimitives() {
524 return form.hasPrimitives();
525 }
526
527 /**
528 * Reports if this type contains a wrapper argument or return value.
529 * Wrappers are types which box primitive values, such as {@link Integer}.
530 * The reference type {@code java.lang.Void} counts as a wrapper,
531 * if it occurs as a return type.
532 * @return true if any of the types are wrappers
533 */
534 public boolean hasWrappers() {
535 return unwrap() != this;
536 }
537
538 /**
539 * Erases all reference types to {@code Object}.
540 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
541 * All primitive types (including {@code void}) will remain unchanged.
542 * @return a version of the original type with all reference types replaced
543 */
544 public MethodType erase() {
545 return form.erasedType();
546 }
547
548 /**
549 * Erases all reference types to {@code Object}, and all subword types to {@code int}.
550 * This is the reduced type polymorphism used by private methods
551 * such as {@link MethodHandle#invokeBasic invokeBasic}.
552 * @return a version of the original type with all reference and subword types replaced
553 */
554 /*non-public*/ MethodType basicType() {
555 return form.basicType();
556 }
557
558 /**
559 * @return a version of the original type with MethodHandle prepended as the first argument
560 */
561 /*non-public*/ MethodType invokerType() {
562 return insertParameterTypes(0, MethodHandle.class);
563 }
564
565 /**
566 * Converts all types, both reference and primitive, to {@code Object}.
567 * Convenience method for {@link #genericMethodType(int) genericMethodType}.
568 * The expression {@code type.wrap().erase()} produces the same value
569 * as {@code type.generic()}.
570 * @return a version of the original type with all types replaced
571 */
572 public MethodType generic() {
573 return genericMethodType(parameterCount());
574 }
575
576 /*non-public*/ boolean isGeneric() {
577 return this == erase() && !hasPrimitives();
578 }
579
580 /**
581 * Converts all primitive types to their corresponding wrapper types.
582 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
583 * All reference types (including wrapper types) will remain unchanged.
584 * A {@code void} return type is changed to the type {@code java.lang.Void}.
585 * The expression {@code type.wrap().erase()} produces the same value
586 * as {@code type.generic()}.
587 * @return a version of the original type with all primitive types replaced
588 */
589 public MethodType wrap() {
590 return hasPrimitives() ? wrapWithPrims(this) : this;
591 }
592
593 /**
594 * Converts all wrapper types to their corresponding primitive types.
595 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
596 * All primitive types (including {@code void}) will remain unchanged.
597 * A return type of {@code java.lang.Void} is changed to {@code void}.
598 * @return a version of the original type with all wrapper types replaced
599 */
600 public MethodType unwrap() {
601 MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this);
602 return unwrapWithNoPrims(noprims);
603 }
604
605 private static MethodType wrapWithPrims(MethodType pt) {
606 assert(pt.hasPrimitives());
607 MethodType wt = pt.wrapAlt;
608 if (wt == null) {
609 // fill in lazily
610 wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP, MethodTypeForm.WRAP);
611 assert(wt != null);
612 pt.wrapAlt = wt;
613 }
614 return wt;
615 }
616
617 private static MethodType unwrapWithNoPrims(MethodType wt) {
618 assert(!wt.hasPrimitives());
619 MethodType uwt = wt.wrapAlt;
620 if (uwt == null) {
621 // fill in lazily
622 uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP, MethodTypeForm.UNWRAP);
623 if (uwt == null)
624 uwt = wt; // type has no wrappers or prims at all
625 wt.wrapAlt = uwt;
626 }
627 return uwt;
628 }
629
630 /**
631 * Returns the parameter type at the specified index, within this method type.
632 * @param num the index (zero-based) of the desired parameter type
633 * @return the selected parameter type
634 * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
635 */
636 public Class<?> parameterType(int num) {
637 return ptypes[num];
638 }
639 /**
640 * Returns the number of parameter types in this method type.
641 * @return the number of parameter types
642 */
643 public int parameterCount() {
644 return ptypes.length;
645 }
646 /**
647 * Returns the return type of this method type.
648 * @return the return type
649 */
650 public Class<?> returnType() {
651 return rtype;
652 }
653
654 /**
655 * Presents the parameter types as a list (a convenience method).
656 * The list will be immutable.
657 * @return the parameter types (as an immutable list)
658 */
659 public List<Class<?>> parameterList() {
660 return Collections.unmodifiableList(Arrays.asList(ptypes));
661 }
662
663 /*non-public*/ Class<?> lastParameterType() {
664 int len = ptypes.length;
665 return len == 0 ? void.class : ptypes[len-1];
666 }
667
668 /**
669 * Presents the parameter types as an array (a convenience method).
670 * Changes to the array will not result in changes to the type.
671 * @return the parameter types (as a fresh copy if necessary)
672 */
673 public Class<?>[] parameterArray() {
674 return ptypes.clone();
675 }
676
677 /**
678 * Compares the specified object with this type for equality.
679 * That is, it returns <tt>true</tt> if and only if the specified object
680 * is also a method type with exactly the same parameters and return type.
681 * @param x object to compare
682 * @see Object#equals(Object)
683 */
684 @Override
685 public boolean equals(Object x) {
686 return this == x || x instanceof MethodType && equals((MethodType)x);
687 }
688
689 private boolean equals(MethodType that) {
690 return this.rtype == that.rtype
691 && Arrays.equals(this.ptypes, that.ptypes);
692 }
693
694 /**
695 * Returns the hash code value for this method type.
696 * It is defined to be the same as the hashcode of a List
697 * whose elements are the return type followed by the
698 * parameter types.
699 * @return the hash code value for this method type
700 * @see Object#hashCode()
701 * @see #equals(Object)
702 * @see List#hashCode()
703 */
704 @Override
705 public int hashCode() {
706 int hashCode = 31 + rtype.hashCode();
707 for (Class<?> ptype : ptypes)
708 hashCode = 31*hashCode + ptype.hashCode();
709 return hashCode;
710 }
711
712 /**
713 * Returns a string representation of the method type,
714 * of the form {@code "(PT0,PT1...)RT"}.
715 * The string representation of a method type is a
716 * parenthesis enclosed, comma separated list of type names,
717 * followed immediately by the return type.
718 * <p>
719 * Each type is represented by its
720 * {@link java.lang.Class#getSimpleName simple name}.
721 */
722 @Override
723 public String toString() {
724 StringBuilder sb = new StringBuilder();
725 sb.append("(");
726 for (int i = 0; i < ptypes.length; i++) {
727 if (i > 0) sb.append(",");
728 sb.append(ptypes[i].getSimpleName());
729 }
730 sb.append(")");
731 sb.append(rtype.getSimpleName());
732 return sb.toString();
733 }
734
735
736 /*non-public*/
737 boolean isViewableAs(MethodType newType) {
738 if (!VerifyType.isNullConversion(returnType(), newType.returnType(), true))
739 return false;
740 int argc = parameterCount();
741 if (argc != newType.parameterCount())
742 return false;
743 for (int i = 0; i < argc; i++) {
744 if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i), true))
745 return false;
746 }
747 return true;
748 }
749 /*non-public*/
750 boolean isCastableTo(MethodType newType) {
751 int argc = parameterCount();
752 if (argc != newType.parameterCount())
753 return false;
754 return true;
755 }
756 /*non-public*/
757 boolean isConvertibleTo(MethodType newType) {
758 if (!canConvert(returnType(), newType.returnType()))
759 return false;
760 int argc = parameterCount();
761 if (argc != newType.parameterCount())
762 return false;
763 for (int i = 0; i < argc; i++) {
764 if (!canConvert(newType.parameterType(i), parameterType(i)))
765 return false;
766 }
767 return true;
768 }
769 /*non-public*/
770 static boolean canConvert(Class<?> src, Class<?> dst) {
771 // short-circuit a few cases:
772 if (src == dst || dst == Object.class) return true;
773 // the remainder of this logic is documented in MethodHandle.asType
774 if (src.isPrimitive()) {
775 // can force void to an explicit null, a la reflect.Method.invoke
776 // can also force void to a primitive zero, by analogy
777 if (src == void.class) return true; //or !dst.isPrimitive()?
778 Wrapper sw = Wrapper.forPrimitiveType(src);
779 if (dst.isPrimitive()) {
780 // P->P must widen
781 return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw);
782 } else {
783 // P->R must box and widen
784 return dst.isAssignableFrom(sw.wrapperType());
785 }
786 } else if (dst.isPrimitive()) {
787 // any value can be dropped
788 if (dst == void.class) return true;
789 Wrapper dw = Wrapper.forPrimitiveType(dst);
790 // R->P must be able to unbox (from a dynamically chosen type) and widen
791 // For example:
792 // Byte/Number/Comparable/Object -> dw:Byte -> byte.
793 // Character/Comparable/Object -> dw:Character -> char
794 // Boolean/Comparable/Object -> dw:Boolean -> boolean
795 // This means that dw must be cast-compatible with src.
796 if (src.isAssignableFrom(dw.wrapperType())) {
797 return true;
798 }
799 // The above does not work if the source reference is strongly typed
800 // to a wrapper whose primitive must be widened. For example:
801 // Byte -> unbox:byte -> short/int/long/float/double
802 // Character -> unbox:char -> int/long/float/double
803 if (Wrapper.isWrapperType(src) &&
804 dw.isConvertibleFrom(Wrapper.forWrapperType(src))) {
805 // can unbox from src and then widen to dst
806 return true;
807 }
808 // We have already covered cases which arise due to runtime unboxing
809 // of a reference type which covers several wrapper types:
810 // Object -> cast:Integer -> unbox:int -> long/float/double
811 // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double
812 // An marginal case is Number -> dw:Character -> char, which would be OK if there were a
813 // subclass of Number which wraps a value that can convert to char.
814 // Since there is none, we don't need an extra check here to cover char or boolean.
815 return false;
816 } else {
817 // R->R always works, since null is always valid dynamically
818 return true;
819 }
820 }
821
822 /// Queries which have to do with the bytecode architecture
823
824 /** Reports the number of JVM stack slots required to invoke a method
825 * of this type. Note that (for historical reasons) the JVM requires
826 * a second stack slot to pass long and double arguments.
827 * So this method returns {@link #parameterCount() parameterCount} plus the
828 * number of long and double parameters (if any).
829 * <p>
830 * This method is included for the benefit of applications that must
831 * generate bytecodes that process method handles and invokedynamic.
832 * @return the number of JVM stack slots for this type's parameters
833 */
834 /*non-public*/ int parameterSlotCount() {
835 return form.parameterSlotCount();
836 }
837
838 /*non-public*/ Invokers invokers() {
839 Invokers inv = invokers;
840 if (inv != null) return inv;
841 invokers = inv = new Invokers(this);
842 return inv;
843 }
844
845 /** Reports the number of JVM stack slots which carry all parameters including and after
846 * the given position, which must be in the range of 0 to
847 * {@code parameterCount} inclusive. Successive parameters are
848 * more shallowly stacked, and parameters are indexed in the bytecodes
849 * according to their trailing edge. Thus, to obtain the depth
850 * in the outgoing call stack of parameter {@code N}, obtain
851 * the {@code parameterSlotDepth} of its trailing edge
852 * at position {@code N+1}.
853 * <p>
854 * Parameters of type {@code long} and {@code double} occupy
855 * two stack slots (for historical reasons) and all others occupy one.
856 * Therefore, the number returned is the number of arguments
857 * <em>including</em> and <em>after</em> the given parameter,
858 * <em>plus</em> the number of long or double arguments
859 * at or after after the argument for the given parameter.
860 * <p>
861 * This method is included for the benefit of applications that must
862 * generate bytecodes that process method handles and invokedynamic.
863 * @param num an index (zero-based, inclusive) within the parameter types
864 * @return the index of the (shallowest) JVM stack slot transmitting the
865 * given parameter
866 * @throws IllegalArgumentException if {@code num} is negative or greater than {@code parameterCount()}
867 */
868 /*non-public*/ int parameterSlotDepth(int num) {
869 if (num < 0 || num > ptypes.length)
870 parameterType(num); // force a range check
871 return form.parameterToArgSlot(num-1);
872 }
873
874 /** Reports the number of JVM stack slots required to receive a return value
875 * from a method of this type.
876 * If the {@link #returnType() return type} is void, it will be zero,
877 * else if the return type is long or double, it will be two, else one.
878 * <p>
879 * This method is included for the benefit of applications that must
880 * generate bytecodes that process method handles and invokedynamic.
881 * @return the number of JVM stack slots (0, 1, or 2) for this type's return value
882 * Will be removed for PFD.
883 */
884 /*non-public*/ int returnSlotCount() {
885 return form.returnSlotCount();
886 }
887
888 /**
889 * Finds or creates an instance of a method type, given the spelling of its bytecode descriptor.
890 * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
891 * Any class or interface name embedded in the descriptor string
892 * will be resolved by calling {@link ClassLoader#loadClass(java.lang.String)}
893 * on the given loader (or if it is null, on the system class loader).
894 * <p>
895 * Note that it is possible to encounter method types which cannot be
896 * constructed by this method, because their component types are
897 * not all reachable from a common class loader.
898 * <p>
899 * This method is included for the benefit of applications that must
900 * generate bytecodes that process method handles and {@code invokedynamic}.
901 * @param descriptor a bytecode-level type descriptor string "(T...)T"
902 * @param loader the class loader in which to look up the types
903 * @return a method type matching the bytecode-level type descriptor
904 * @throws NullPointerException if the string is null
905 * @throws IllegalArgumentException if the string is not well-formed
906 * @throws TypeNotPresentException if a named type cannot be found
907 */
908 public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader)
909 throws IllegalArgumentException, TypeNotPresentException
910 {
911 if (!descriptor.startsWith("(") || // also generates NPE if needed
912 descriptor.indexOf(')') < 0 ||
913 descriptor.indexOf('.') >= 0)
914 throw newIllegalArgumentException("not a method descriptor: "+descriptor);
915 List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader);
916 Class<?> rtype = types.remove(types.size() - 1);
917 checkSlotCount(types.size());
918 Class<?>[] ptypes = listToArray(types);
919 return makeImpl(rtype, ptypes, true);
920 }
921
922 /**
923 * Produces a bytecode descriptor representation of the method type.
924 * <p>
925 * Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}.
926 * Two distinct classes which share a common name but have different class loaders
927 * will appear identical when viewed within descriptor strings.
928 * <p>
929 * This method is included for the benefit of applications that must
930 * generate bytecodes that process method handles and {@code invokedynamic}.
931 * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString},
932 * because the latter requires a suitable class loader argument.
933 * @return the bytecode type descriptor representation
934 */
935 public String toMethodDescriptorString() {
936 String desc = methodDescriptor;
937 if (desc == null) {
938 desc = BytecodeDescriptor.unparse(this);
939 methodDescriptor = desc;
940 }
941 return desc;
942 }
943
944 /*non-public*/ static String toFieldDescriptorString(Class<?> cls) {
945 return BytecodeDescriptor.unparse(cls);
946 }
947
948 /// Serialization.
949
950 /**
951 * There are no serializable fields for {@code MethodType}.
952 */
953 private static final java.io.ObjectStreamField[] serialPersistentFields = { };
954
955 /**
956 * Save the {@code MethodType} instance to a stream.
957 *
958 * @serialData
959 * For portability, the serialized format does not refer to named fields.
960 * Instead, the return type and parameter type arrays are written directly
961 * from the {@code writeObject} method, using two calls to {@code s.writeObject}
962 * as follows:
963 * <blockquote><pre>{@code
964 s.writeObject(this.returnType());
965 s.writeObject(this.parameterArray());
966 * }</pre></blockquote>
967 * <p>
968 * The deserialized field values are checked as if they were
969 * provided to the factory method {@link #methodType(Class,Class[]) methodType}.
970 * For example, null values, or {@code void} parameter types,
971 * will lead to exceptions during deserialization.
972 * @param s the stream to write the object to
973 * @throws java.io.IOException if there is a problem writing the object
974 */
975 private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
976 s.defaultWriteObject(); // requires serialPersistentFields to be an empty array
977 s.writeObject(returnType());
978 s.writeObject(parameterArray());
979 }
980
981 /**
982 * Reconstitute the {@code MethodType} instance from a stream (that is,
983 * deserialize it).
984 * This instance is a scratch object with bogus final fields.
985 * It provides the parameters to the factory method called by
986 * {@link #readResolve readResolve}.
987 * After that call it is discarded.
988 * @param s the stream to read the object from
989 * @throws java.io.IOException if there is a problem reading the object
990 * @throws ClassNotFoundException if one of the component classes cannot be resolved
991 * @see #MethodType()
992 * @see #readResolve
993 * @see #writeObject
994 */
995 private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
996 s.defaultReadObject(); // requires serialPersistentFields to be an empty array
997
998 Class<?> returnType = (Class<?>) s.readObject();
999 Class<?>[] parameterArray = (Class<?>[]) s.readObject();
1000
1001 // Probably this object will never escape, but let's check
1002 // the field values now, just to be sure.
1003 checkRtype(returnType);
1004 checkPtypes(parameterArray);
1005
1006 parameterArray = parameterArray.clone(); // make sure it is unshared
1007 MethodType_init(returnType, parameterArray);
1008 }
1009
1010 /**
1011 * For serialization only.
1012 * Sets the final fields to null, pending {@code Unsafe.putObject}.
1013 */
1014 private MethodType() {
1015 this.rtype = null;
1016 this.ptypes = null;
1017 }
1018 private void MethodType_init(Class<?> rtype, Class<?>[] ptypes) {
1019 // In order to communicate these values to readResolve, we must
1020 // store them into the implementation-specific final fields.
1021 checkRtype(rtype);
1022 checkPtypes(ptypes);
1023 UNSAFE.putObject(this, rtypeOffset, rtype);
1024 UNSAFE.putObject(this, ptypesOffset, ptypes);
1025 }
1026
1027 // Support for resetting final fields while deserializing
1028 private static final long rtypeOffset, ptypesOffset;
1029 static {
1030 try {
1031 rtypeOffset = UNSAFE.objectFieldOffset
1032 (MethodType.class.getDeclaredField("rtype"));
1033 ptypesOffset = UNSAFE.objectFieldOffset
1034 (MethodType.class.getDeclaredField("ptypes"));
1035 } catch (Exception ex) {
1036 throw new Error(ex);
1037 }
1038 }
1039
1040 /**
1041 * Resolves and initializes a {@code MethodType} object
1042 * after serialization.
1043 * @return the fully initialized {@code MethodType} object
1044 */
1045 private Object readResolve() {
1046 // Do not use a trusted path for deserialization:
1047 //return makeImpl(rtype, ptypes, true);
1048 // Verify all operands, and make sure ptypes is unshared:
1049 return methodType(rtype, ptypes);
1050 }
1051
1052 /**
1053 * Simple implementation of weak concurrent intern set.
1054 *
1055 * @param <T> interned type
1056 */
1057 private static class ConcurrentWeakInternSet<T> {
1058
1059 private final ConcurrentMap<WeakEntry<T>, WeakEntry<T>> map;
1060 private final ReferenceQueue<T> stale;
1061
1062 public ConcurrentWeakInternSet() {
1063 this.map = new ConcurrentHashMap<>();
1064 this.stale = new ReferenceQueue<>();
1065 }
1066
1067 /**
1068 * Get the existing interned element.
1069 * This method returns null if no element is interned.
1070 *
1071 * @param elem element to look up
1072 * @return the interned element
1073 */
1074 public T get(T elem) {
1075 if (elem == null) throw new NullPointerException();
1076 expungeStaleElements();
1077
1078 WeakEntry<T> value = map.get(new WeakEntry<>(elem));
1079 if (value != null) {
1080 T res = value.get();
1081 if (res != null) {
1082 return res;
1083 }
1084 }
1085 return null;
1086 }
1087
1088 /**
1089 * Interns the element.
1090 * Always returns non-null element, matching the one in the intern set.
1091 * Under the race against another add(), it can return <i>different</i>
1092 * element, if another thread beats us to interning it.
1093 *
1094 * @param elem element to add
1095 * @return element that was actually added
1096 */
1097 public T add(T elem) {
1098 if (elem == null) throw new NullPointerException();
1099
1100 // Playing double race here, and so spinloop is required.
1101 // First race is with two concurrent updaters.
1102 // Second race is with GC purging weak ref under our feet.
1103 // Hopefully, we almost always end up with a single pass.
1104 T interned;
1105 WeakEntry<T> e = new WeakEntry<>(elem, stale);
1106 do {
1107 expungeStaleElements();
1108 WeakEntry<T> exist = map.putIfAbsent(e, e);
1109 interned = (exist == null) ? elem : exist.get();
1110 } while (interned == null);
1111 return interned;
1112 }
1113
1114 private void expungeStaleElements() {
1115 Reference<? extends T> reference;
1116 while ((reference = stale.poll()) != null) {
1117 map.remove(reference);
1118 }
1119 }
1120
1121 private static class WeakEntry<T> extends WeakReference<T> {
1122
1123 public final int hashcode;
1124
1125 public WeakEntry(T key, ReferenceQueue<T> queue) {
1126 super(key, queue);
1127 hashcode = key.hashCode();
1128 }
1129
1130 public WeakEntry(T key) {
1131 super(key);
1132 hashcode = key.hashCode();
1133 }
1134
1135 @Override
1136 public boolean equals(Object obj) {
1137 if (obj instanceof WeakEntry) {
1138 Object that = ((WeakEntry) obj).get();
1139 Object mine = get();
1140 return (that == null || mine == null) ? (this == obj) : mine.equals(that);
1141 }
1142 return false;
1143 }
1144
1145 @Override
1146 public int hashCode() {
1147 return hashcode;
1148 }
1149
1150 }
1151 }
1152
1153 }