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src/share/classes/com/sun/tools/javac/code/Types.java@4868a36f6fd8
src/share/classes/com/sun/tools/javac/code/Types.java
Tue, 28 Dec 2010 15:54:52 -0800
- author
- ohair
- date
- Tue, 28 Dec 2010 15:54:52 -0800
- changeset 798
- 4868a36f6fd8
- parent 795
- 7b99f98b3035
- child 816
- 7c537f4298fb
- permissions
- -rw-r--r--
6962318: Update copyright year
Reviewed-by: xdono
1 /*
2 * Copyright (c) 2003, 2010, 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 */
26 package com.sun.tools.javac.code;
28 import java.lang.ref.SoftReference;
29 import java.util.*;
31 import com.sun.tools.javac.util.*;
32 import com.sun.tools.javac.util.List;
34 import com.sun.tools.javac.jvm.ClassReader;
35 import com.sun.tools.javac.code.Attribute.RetentionPolicy;
36 import com.sun.tools.javac.code.Lint.LintCategory;
37 import com.sun.tools.javac.comp.Check;
39 import static com.sun.tools.javac.code.Type.*;
40 import static com.sun.tools.javac.code.TypeTags.*;
41 import static com.sun.tools.javac.code.Symbol.*;
42 import static com.sun.tools.javac.code.Flags.*;
43 import static com.sun.tools.javac.code.BoundKind.*;
44 import static com.sun.tools.javac.util.ListBuffer.lb;
46 /**
47 * Utility class containing various operations on types.
48 *
49 * <p>Unless other names are more illustrative, the following naming
50 * conventions should be observed in this file:
51 *
52 * <dl>
53 * <dt>t</dt>
54 * <dd>If the first argument to an operation is a type, it should be named t.</dd>
55 * <dt>s</dt>
56 * <dd>Similarly, if the second argument to an operation is a type, it should be named s.</dd>
57 * <dt>ts</dt>
58 * <dd>If an operations takes a list of types, the first should be named ts.</dd>
59 * <dt>ss</dt>
60 * <dd>A second list of types should be named ss.</dd>
61 * </dl>
62 *
63 * <p><b>This is NOT part of any supported API.
64 * If you write code that depends on this, you do so at your own risk.
65 * This code and its internal interfaces are subject to change or
66 * deletion without notice.</b>
67 */
68 public class Types {
69 protected static final Context.Key<Types> typesKey =
70 new Context.Key<Types>();
72 final Symtab syms;
73 final Scope.ScopeCounter scopeCounter;
74 final JavacMessages messages;
75 final Names names;
76 final boolean allowBoxing;
77 final ClassReader reader;
78 final Source source;
79 final Check chk;
80 List<Warner> warnStack = List.nil();
81 final Name capturedName;
83 // <editor-fold defaultstate="collapsed" desc="Instantiating">
84 public static Types instance(Context context) {
85 Types instance = context.get(typesKey);
86 if (instance == null)
87 instance = new Types(context);
88 return instance;
89 }
91 protected Types(Context context) {
92 context.put(typesKey, this);
93 syms = Symtab.instance(context);
94 scopeCounter = Scope.ScopeCounter.instance(context);
95 names = Names.instance(context);
96 allowBoxing = Source.instance(context).allowBoxing();
97 reader = ClassReader.instance(context);
98 source = Source.instance(context);
99 chk = Check.instance(context);
100 capturedName = names.fromString("<captured wildcard>");
101 messages = JavacMessages.instance(context);
102 }
103 // </editor-fold>
105 // <editor-fold defaultstate="collapsed" desc="upperBound">
106 /**
107 * The "rvalue conversion".<br>
108 * The upper bound of most types is the type
109 * itself. Wildcards, on the other hand have upper
110 * and lower bounds.
111 * @param t a type
112 * @return the upper bound of the given type
113 */
114 public Type upperBound(Type t) {
115 return upperBound.visit(t);
116 }
117 // where
118 private final MapVisitor<Void> upperBound = new MapVisitor<Void>() {
120 @Override
121 public Type visitWildcardType(WildcardType t, Void ignored) {
122 if (t.isSuperBound())
123 return t.bound == null ? syms.objectType : t.bound.bound;
124 else
125 return visit(t.type);
126 }
128 @Override
129 public Type visitCapturedType(CapturedType t, Void ignored) {
130 return visit(t.bound);
131 }
132 };
133 // </editor-fold>
135 // <editor-fold defaultstate="collapsed" desc="lowerBound">
136 /**
137 * The "lvalue conversion".<br>
138 * The lower bound of most types is the type
139 * itself. Wildcards, on the other hand have upper
140 * and lower bounds.
141 * @param t a type
142 * @return the lower bound of the given type
143 */
144 public Type lowerBound(Type t) {
145 return lowerBound.visit(t);
146 }
147 // where
148 private final MapVisitor<Void> lowerBound = new MapVisitor<Void>() {
150 @Override
151 public Type visitWildcardType(WildcardType t, Void ignored) {
152 return t.isExtendsBound() ? syms.botType : visit(t.type);
153 }
155 @Override
156 public Type visitCapturedType(CapturedType t, Void ignored) {
157 return visit(t.getLowerBound());
158 }
159 };
160 // </editor-fold>
162 // <editor-fold defaultstate="collapsed" desc="isUnbounded">
163 /**
164 * Checks that all the arguments to a class are unbounded
165 * wildcards or something else that doesn't make any restrictions
166 * on the arguments. If a class isUnbounded, a raw super- or
167 * subclass can be cast to it without a warning.
168 * @param t a type
169 * @return true iff the given type is unbounded or raw
170 */
171 public boolean isUnbounded(Type t) {
172 return isUnbounded.visit(t);
173 }
174 // where
175 private final UnaryVisitor<Boolean> isUnbounded = new UnaryVisitor<Boolean>() {
177 public Boolean visitType(Type t, Void ignored) {
178 return true;
179 }
181 @Override
182 public Boolean visitClassType(ClassType t, Void ignored) {
183 List<Type> parms = t.tsym.type.allparams();
184 List<Type> args = t.allparams();
185 while (parms.nonEmpty()) {
186 WildcardType unb = new WildcardType(syms.objectType,
187 BoundKind.UNBOUND,
188 syms.boundClass,
189 (TypeVar)parms.head);
190 if (!containsType(args.head, unb))
191 return false;
192 parms = parms.tail;
193 args = args.tail;
194 }
195 return true;
196 }
197 };
198 // </editor-fold>
200 // <editor-fold defaultstate="collapsed" desc="asSub">
201 /**
202 * Return the least specific subtype of t that starts with symbol
203 * sym. If none exists, return null. The least specific subtype
204 * is determined as follows:
205 *
206 * <p>If there is exactly one parameterized instance of sym that is a
207 * subtype of t, that parameterized instance is returned.<br>
208 * Otherwise, if the plain type or raw type `sym' is a subtype of
209 * type t, the type `sym' itself is returned. Otherwise, null is
210 * returned.
211 */
212 public Type asSub(Type t, Symbol sym) {
213 return asSub.visit(t, sym);
214 }
215 // where
216 private final SimpleVisitor<Type,Symbol> asSub = new SimpleVisitor<Type,Symbol>() {
218 public Type visitType(Type t, Symbol sym) {
219 return null;
220 }
222 @Override
223 public Type visitClassType(ClassType t, Symbol sym) {
224 if (t.tsym == sym)
225 return t;
226 Type base = asSuper(sym.type, t.tsym);
227 if (base == null)
228 return null;
229 ListBuffer<Type> from = new ListBuffer<Type>();
230 ListBuffer<Type> to = new ListBuffer<Type>();
231 try {
232 adapt(base, t, from, to);
233 } catch (AdaptFailure ex) {
234 return null;
235 }
236 Type res = subst(sym.type, from.toList(), to.toList());
237 if (!isSubtype(res, t))
238 return null;
239 ListBuffer<Type> openVars = new ListBuffer<Type>();
240 for (List<Type> l = sym.type.allparams();
241 l.nonEmpty(); l = l.tail)
242 if (res.contains(l.head) && !t.contains(l.head))
243 openVars.append(l.head);
244 if (openVars.nonEmpty()) {
245 if (t.isRaw()) {
246 // The subtype of a raw type is raw
247 res = erasure(res);
248 } else {
249 // Unbound type arguments default to ?
250 List<Type> opens = openVars.toList();
251 ListBuffer<Type> qs = new ListBuffer<Type>();
252 for (List<Type> iter = opens; iter.nonEmpty(); iter = iter.tail) {
253 qs.append(new WildcardType(syms.objectType, BoundKind.UNBOUND, syms.boundClass, (TypeVar) iter.head));
254 }
255 res = subst(res, opens, qs.toList());
256 }
257 }
258 return res;
259 }
261 @Override
262 public Type visitErrorType(ErrorType t, Symbol sym) {
263 return t;
264 }
265 };
266 // </editor-fold>
268 // <editor-fold defaultstate="collapsed" desc="isConvertible">
269 /**
270 * Is t a subtype of or convertiable via boxing/unboxing
271 * convertions to s?
272 */
273 public boolean isConvertible(Type t, Type s, Warner warn) {
274 boolean tPrimitive = t.isPrimitive();
275 boolean sPrimitive = s.isPrimitive();
276 if (tPrimitive == sPrimitive) {
277 checkUnsafeVarargsConversion(t, s, warn);
278 return isSubtypeUnchecked(t, s, warn);
279 }
280 if (!allowBoxing) return false;
281 return tPrimitive
282 ? isSubtype(boxedClass(t).type, s)
283 : isSubtype(unboxedType(t), s);
284 }
285 //where
286 private void checkUnsafeVarargsConversion(Type t, Type s, Warner warn) {
287 if (t.tag != ARRAY || isReifiable(t)) return;
288 ArrayType from = (ArrayType)t;
289 boolean shouldWarn = false;
290 switch (s.tag) {
291 case ARRAY:
292 ArrayType to = (ArrayType)s;
293 shouldWarn = from.isVarargs() &&
294 !to.isVarargs() &&
295 !isReifiable(from);
296 break;
297 case CLASS:
298 shouldWarn = from.isVarargs() &&
299 isSubtype(from, s);
300 break;
301 }
302 if (shouldWarn) {
303 warn.warn(LintCategory.VARARGS);
304 }
305 }
307 /**
308 * Is t a subtype of or convertiable via boxing/unboxing
309 * convertions to s?
310 */
311 public boolean isConvertible(Type t, Type s) {
312 return isConvertible(t, s, Warner.noWarnings);
313 }
314 // </editor-fold>
316 // <editor-fold defaultstate="collapsed" desc="isSubtype">
317 /**
318 * Is t an unchecked subtype of s?
319 */
320 public boolean isSubtypeUnchecked(Type t, Type s) {
321 return isSubtypeUnchecked(t, s, Warner.noWarnings);
322 }
323 /**
324 * Is t an unchecked subtype of s?
325 */
326 public boolean isSubtypeUnchecked(Type t, Type s, Warner warn) {
327 if (t.tag == ARRAY && s.tag == ARRAY) {
328 if (((ArrayType)t).elemtype.tag <= lastBaseTag) {
329 return isSameType(elemtype(t), elemtype(s));
330 } else {
331 ArrayType from = (ArrayType)t;
332 ArrayType to = (ArrayType)s;
333 if (from.isVarargs() &&
334 !to.isVarargs() &&
335 !isReifiable(from)) {
336 warn.warn(LintCategory.VARARGS);
337 }
338 return isSubtypeUnchecked(elemtype(t), elemtype(s), warn);
339 }
340 } else if (isSubtype(t, s)) {
341 return true;
342 }
343 else if (t.tag == TYPEVAR) {
344 return isSubtypeUnchecked(t.getUpperBound(), s, warn);
345 }
346 else if (s.tag == UNDETVAR) {
347 UndetVar uv = (UndetVar)s;
348 if (uv.inst != null)
349 return isSubtypeUnchecked(t, uv.inst, warn);
350 }
351 else if (!s.isRaw()) {
352 Type t2 = asSuper(t, s.tsym);
353 if (t2 != null && t2.isRaw()) {
354 if (isReifiable(s))
355 warn.silentWarn(LintCategory.UNCHECKED);
356 else
357 warn.warn(LintCategory.UNCHECKED);
358 return true;
359 }
360 }
361 return false;
362 }
364 /**
365 * Is t a subtype of s?<br>
366 * (not defined for Method and ForAll types)
367 */
368 final public boolean isSubtype(Type t, Type s) {
369 return isSubtype(t, s, true);
370 }
371 final public boolean isSubtypeNoCapture(Type t, Type s) {
372 return isSubtype(t, s, false);
373 }
374 public boolean isSubtype(Type t, Type s, boolean capture) {
375 if (t == s)
376 return true;
378 if (s.tag >= firstPartialTag)
379 return isSuperType(s, t);
381 if (s.isCompound()) {
382 for (Type s2 : interfaces(s).prepend(supertype(s))) {
383 if (!isSubtype(t, s2, capture))
384 return false;
385 }
386 return true;
387 }
389 Type lower = lowerBound(s);
390 if (s != lower)
391 return isSubtype(capture ? capture(t) : t, lower, false);
393 return isSubtype.visit(capture ? capture(t) : t, s);
394 }
395 // where
396 private TypeRelation isSubtype = new TypeRelation()
397 {
398 public Boolean visitType(Type t, Type s) {
399 switch (t.tag) {
400 case BYTE: case CHAR:
401 return (t.tag == s.tag ||
402 t.tag + 2 <= s.tag && s.tag <= DOUBLE);
403 case SHORT: case INT: case LONG: case FLOAT: case DOUBLE:
404 return t.tag <= s.tag && s.tag <= DOUBLE;
405 case BOOLEAN: case VOID:
406 return t.tag == s.tag;
407 case TYPEVAR:
408 return isSubtypeNoCapture(t.getUpperBound(), s);
409 case BOT:
410 return
411 s.tag == BOT || s.tag == CLASS ||
412 s.tag == ARRAY || s.tag == TYPEVAR;
413 case NONE:
414 return false;
415 default:
416 throw new AssertionError("isSubtype " + t.tag);
417 }
418 }
420 private Set<TypePair> cache = new HashSet<TypePair>();
422 private boolean containsTypeRecursive(Type t, Type s) {
423 TypePair pair = new TypePair(t, s);
424 if (cache.add(pair)) {
425 try {
426 return containsType(t.getTypeArguments(),
427 s.getTypeArguments());
428 } finally {
429 cache.remove(pair);
430 }
431 } else {
432 return containsType(t.getTypeArguments(),
433 rewriteSupers(s).getTypeArguments());
434 }
435 }
437 private Type rewriteSupers(Type t) {
438 if (!t.isParameterized())
439 return t;
440 ListBuffer<Type> from = lb();
441 ListBuffer<Type> to = lb();
442 adaptSelf(t, from, to);
443 if (from.isEmpty())
444 return t;
445 ListBuffer<Type> rewrite = lb();
446 boolean changed = false;
447 for (Type orig : to.toList()) {
448 Type s = rewriteSupers(orig);
449 if (s.isSuperBound() && !s.isExtendsBound()) {
450 s = new WildcardType(syms.objectType,
451 BoundKind.UNBOUND,
452 syms.boundClass);
453 changed = true;
454 } else if (s != orig) {
455 s = new WildcardType(upperBound(s),
456 BoundKind.EXTENDS,
457 syms.boundClass);
458 changed = true;
459 }
460 rewrite.append(s);
461 }
462 if (changed)
463 return subst(t.tsym.type, from.toList(), rewrite.toList());
464 else
465 return t;
466 }
468 @Override
469 public Boolean visitClassType(ClassType t, Type s) {
470 Type sup = asSuper(t, s.tsym);
471 return sup != null
472 && sup.tsym == s.tsym
473 // You're not allowed to write
474 // Vector<Object> vec = new Vector<String>();
475 // But with wildcards you can write
476 // Vector<? extends Object> vec = new Vector<String>();
477 // which means that subtype checking must be done
478 // here instead of same-type checking (via containsType).
479 && (!s.isParameterized() || containsTypeRecursive(s, sup))
480 && isSubtypeNoCapture(sup.getEnclosingType(),
481 s.getEnclosingType());
482 }
484 @Override
485 public Boolean visitArrayType(ArrayType t, Type s) {
486 if (s.tag == ARRAY) {
487 if (t.elemtype.tag <= lastBaseTag)
488 return isSameType(t.elemtype, elemtype(s));
489 else
490 return isSubtypeNoCapture(t.elemtype, elemtype(s));
491 }
493 if (s.tag == CLASS) {
494 Name sname = s.tsym.getQualifiedName();
495 return sname == names.java_lang_Object
496 || sname == names.java_lang_Cloneable
497 || sname == names.java_io_Serializable;
498 }
500 return false;
501 }
503 @Override
504 public Boolean visitUndetVar(UndetVar t, Type s) {
505 //todo: test against origin needed? or replace with substitution?
506 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
507 return true;
509 if (t.inst != null)
510 return isSubtypeNoCapture(t.inst, s); // TODO: ", warn"?
512 t.hibounds = t.hibounds.prepend(s);
513 return true;
514 }
516 @Override
517 public Boolean visitErrorType(ErrorType t, Type s) {
518 return true;
519 }
520 };
522 /**
523 * Is t a subtype of every type in given list `ts'?<br>
524 * (not defined for Method and ForAll types)<br>
525 * Allows unchecked conversions.
526 */
527 public boolean isSubtypeUnchecked(Type t, List<Type> ts, Warner warn) {
528 for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
529 if (!isSubtypeUnchecked(t, l.head, warn))
530 return false;
531 return true;
532 }
534 /**
535 * Are corresponding elements of ts subtypes of ss? If lists are
536 * of different length, return false.
537 */
538 public boolean isSubtypes(List<Type> ts, List<Type> ss) {
539 while (ts.tail != null && ss.tail != null
540 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
541 isSubtype(ts.head, ss.head)) {
542 ts = ts.tail;
543 ss = ss.tail;
544 }
545 return ts.tail == null && ss.tail == null;
546 /*inlined: ts.isEmpty() && ss.isEmpty();*/
547 }
549 /**
550 * Are corresponding elements of ts subtypes of ss, allowing
551 * unchecked conversions? If lists are of different length,
552 * return false.
553 **/
554 public boolean isSubtypesUnchecked(List<Type> ts, List<Type> ss, Warner warn) {
555 while (ts.tail != null && ss.tail != null
556 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
557 isSubtypeUnchecked(ts.head, ss.head, warn)) {
558 ts = ts.tail;
559 ss = ss.tail;
560 }
561 return ts.tail == null && ss.tail == null;
562 /*inlined: ts.isEmpty() && ss.isEmpty();*/
563 }
564 // </editor-fold>
566 // <editor-fold defaultstate="collapsed" desc="isSuperType">
567 /**
568 * Is t a supertype of s?
569 */
570 public boolean isSuperType(Type t, Type s) {
571 switch (t.tag) {
572 case ERROR:
573 return true;
574 case UNDETVAR: {
575 UndetVar undet = (UndetVar)t;
576 if (t == s ||
577 undet.qtype == s ||
578 s.tag == ERROR ||
579 s.tag == BOT) return true;
580 if (undet.inst != null)
581 return isSubtype(s, undet.inst);
582 undet.lobounds = undet.lobounds.prepend(s);
583 return true;
584 }
585 default:
586 return isSubtype(s, t);
587 }
588 }
589 // </editor-fold>
591 // <editor-fold defaultstate="collapsed" desc="isSameType">
592 /**
593 * Are corresponding elements of the lists the same type? If
594 * lists are of different length, return false.
595 */
596 public boolean isSameTypes(List<Type> ts, List<Type> ss) {
597 while (ts.tail != null && ss.tail != null
598 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
599 isSameType(ts.head, ss.head)) {
600 ts = ts.tail;
601 ss = ss.tail;
602 }
603 return ts.tail == null && ss.tail == null;
604 /*inlined: ts.isEmpty() && ss.isEmpty();*/
605 }
607 /**
608 * Is t the same type as s?
609 */
610 public boolean isSameType(Type t, Type s) {
611 return isSameType.visit(t, s);
612 }
613 // where
614 private TypeRelation isSameType = new TypeRelation() {
616 public Boolean visitType(Type t, Type s) {
617 if (t == s)
618 return true;
620 if (s.tag >= firstPartialTag)
621 return visit(s, t);
623 switch (t.tag) {
624 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
625 case DOUBLE: case BOOLEAN: case VOID: case BOT: case NONE:
626 return t.tag == s.tag;
627 case TYPEVAR: {
628 if (s.tag == TYPEVAR) {
629 //type-substitution does not preserve type-var types
630 //check that type var symbols and bounds are indeed the same
631 return t.tsym == s.tsym &&
632 visit(t.getUpperBound(), s.getUpperBound());
633 }
634 else {
635 //special case for s == ? super X, where upper(s) = u
636 //check that u == t, where u has been set by Type.withTypeVar
637 return s.isSuperBound() &&
638 !s.isExtendsBound() &&
639 visit(t, upperBound(s));
640 }
641 }
642 default:
643 throw new AssertionError("isSameType " + t.tag);
644 }
645 }
647 @Override
648 public Boolean visitWildcardType(WildcardType t, Type s) {
649 if (s.tag >= firstPartialTag)
650 return visit(s, t);
651 else
652 return false;
653 }
655 @Override
656 public Boolean visitClassType(ClassType t, Type s) {
657 if (t == s)
658 return true;
660 if (s.tag >= firstPartialTag)
661 return visit(s, t);
663 if (s.isSuperBound() && !s.isExtendsBound())
664 return visit(t, upperBound(s)) && visit(t, lowerBound(s));
666 if (t.isCompound() && s.isCompound()) {
667 if (!visit(supertype(t), supertype(s)))
668 return false;
670 HashSet<SingletonType> set = new HashSet<SingletonType>();
671 for (Type x : interfaces(t))
672 set.add(new SingletonType(x));
673 for (Type x : interfaces(s)) {
674 if (!set.remove(new SingletonType(x)))
675 return false;
676 }
677 return (set.isEmpty());
678 }
679 return t.tsym == s.tsym
680 && visit(t.getEnclosingType(), s.getEnclosingType())
681 && containsTypeEquivalent(t.getTypeArguments(), s.getTypeArguments());
682 }
684 @Override
685 public Boolean visitArrayType(ArrayType t, Type s) {
686 if (t == s)
687 return true;
689 if (s.tag >= firstPartialTag)
690 return visit(s, t);
692 return s.tag == ARRAY
693 && containsTypeEquivalent(t.elemtype, elemtype(s));
694 }
696 @Override
697 public Boolean visitMethodType(MethodType t, Type s) {
698 // isSameType for methods does not take thrown
699 // exceptions into account!
700 return hasSameArgs(t, s) && visit(t.getReturnType(), s.getReturnType());
701 }
703 @Override
704 public Boolean visitPackageType(PackageType t, Type s) {
705 return t == s;
706 }
708 @Override
709 public Boolean visitForAll(ForAll t, Type s) {
710 if (s.tag != FORALL)
711 return false;
713 ForAll forAll = (ForAll)s;
714 return hasSameBounds(t, forAll)
715 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
716 }
718 @Override
719 public Boolean visitUndetVar(UndetVar t, Type s) {
720 if (s.tag == WILDCARD)
721 // FIXME, this might be leftovers from before capture conversion
722 return false;
724 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
725 return true;
727 if (t.inst != null)
728 return visit(t.inst, s);
730 t.inst = fromUnknownFun.apply(s);
731 for (List<Type> l = t.lobounds; l.nonEmpty(); l = l.tail) {
732 if (!isSubtype(l.head, t.inst))
733 return false;
734 }
735 for (List<Type> l = t.hibounds; l.nonEmpty(); l = l.tail) {
736 if (!isSubtype(t.inst, l.head))
737 return false;
738 }
739 return true;
740 }
742 @Override
743 public Boolean visitErrorType(ErrorType t, Type s) {
744 return true;
745 }
746 };
747 // </editor-fold>
749 // <editor-fold defaultstate="collapsed" desc="fromUnknownFun">
750 /**
751 * A mapping that turns all unknown types in this type to fresh
752 * unknown variables.
753 */
754 public Mapping fromUnknownFun = new Mapping("fromUnknownFun") {
755 public Type apply(Type t) {
756 if (t.tag == UNKNOWN) return new UndetVar(t);
757 else return t.map(this);
758 }
759 };
760 // </editor-fold>
762 // <editor-fold defaultstate="collapsed" desc="Contains Type">
763 public boolean containedBy(Type t, Type s) {
764 switch (t.tag) {
765 case UNDETVAR:
766 if (s.tag == WILDCARD) {
767 UndetVar undetvar = (UndetVar)t;
768 WildcardType wt = (WildcardType)s;
769 switch(wt.kind) {
770 case UNBOUND: //similar to ? extends Object
771 case EXTENDS: {
772 Type bound = upperBound(s);
773 // We should check the new upper bound against any of the
774 // undetvar's lower bounds.
775 for (Type t2 : undetvar.lobounds) {
776 if (!isSubtype(t2, bound))
777 return false;
778 }
779 undetvar.hibounds = undetvar.hibounds.prepend(bound);
780 break;
781 }
782 case SUPER: {
783 Type bound = lowerBound(s);
784 // We should check the new lower bound against any of the
785 // undetvar's lower bounds.
786 for (Type t2 : undetvar.hibounds) {
787 if (!isSubtype(bound, t2))
788 return false;
789 }
790 undetvar.lobounds = undetvar.lobounds.prepend(bound);
791 break;
792 }
793 }
794 return true;
795 } else {
796 return isSameType(t, s);
797 }
798 case ERROR:
799 return true;
800 default:
801 return containsType(s, t);
802 }
803 }
805 boolean containsType(List<Type> ts, List<Type> ss) {
806 while (ts.nonEmpty() && ss.nonEmpty()
807 && containsType(ts.head, ss.head)) {
808 ts = ts.tail;
809 ss = ss.tail;
810 }
811 return ts.isEmpty() && ss.isEmpty();
812 }
814 /**
815 * Check if t contains s.
816 *
817 * <p>T contains S if:
818 *
819 * <p>{@code L(T) <: L(S) && U(S) <: U(T)}
820 *
821 * <p>This relation is only used by ClassType.isSubtype(), that
822 * is,
823 *
824 * <p>{@code C<S> <: C<T> if T contains S.}
825 *
826 * <p>Because of F-bounds, this relation can lead to infinite
827 * recursion. Thus we must somehow break that recursion. Notice
828 * that containsType() is only called from ClassType.isSubtype().
829 * Since the arguments have already been checked against their
830 * bounds, we know:
831 *
832 * <p>{@code U(S) <: U(T) if T is "super" bound (U(T) *is* the bound)}
833 *
834 * <p>{@code L(T) <: L(S) if T is "extends" bound (L(T) is bottom)}
835 *
836 * @param t a type
837 * @param s a type
838 */
839 public boolean containsType(Type t, Type s) {
840 return containsType.visit(t, s);
841 }
842 // where
843 private TypeRelation containsType = new TypeRelation() {
845 private Type U(Type t) {
846 while (t.tag == WILDCARD) {
847 WildcardType w = (WildcardType)t;
848 if (w.isSuperBound())
849 return w.bound == null ? syms.objectType : w.bound.bound;
850 else
851 t = w.type;
852 }
853 return t;
854 }
856 private Type L(Type t) {
857 while (t.tag == WILDCARD) {
858 WildcardType w = (WildcardType)t;
859 if (w.isExtendsBound())
860 return syms.botType;
861 else
862 t = w.type;
863 }
864 return t;
865 }
867 public Boolean visitType(Type t, Type s) {
868 if (s.tag >= firstPartialTag)
869 return containedBy(s, t);
870 else
871 return isSameType(t, s);
872 }
874 // void debugContainsType(WildcardType t, Type s) {
875 // System.err.println();
876 // System.err.format(" does %s contain %s?%n", t, s);
877 // System.err.format(" %s U(%s) <: U(%s) %s = %s%n",
878 // upperBound(s), s, t, U(t),
879 // t.isSuperBound()
880 // || isSubtypeNoCapture(upperBound(s), U(t)));
881 // System.err.format(" %s L(%s) <: L(%s) %s = %s%n",
882 // L(t), t, s, lowerBound(s),
883 // t.isExtendsBound()
884 // || isSubtypeNoCapture(L(t), lowerBound(s)));
885 // System.err.println();
886 // }
888 @Override
889 public Boolean visitWildcardType(WildcardType t, Type s) {
890 if (s.tag >= firstPartialTag)
891 return containedBy(s, t);
892 else {
893 // debugContainsType(t, s);
894 return isSameWildcard(t, s)
895 || isCaptureOf(s, t)
896 || ((t.isExtendsBound() || isSubtypeNoCapture(L(t), lowerBound(s))) &&
897 (t.isSuperBound() || isSubtypeNoCapture(upperBound(s), U(t))));
898 }
899 }
901 @Override
902 public Boolean visitUndetVar(UndetVar t, Type s) {
903 if (s.tag != WILDCARD)
904 return isSameType(t, s);
905 else
906 return false;
907 }
909 @Override
910 public Boolean visitErrorType(ErrorType t, Type s) {
911 return true;
912 }
913 };
915 public boolean isCaptureOf(Type s, WildcardType t) {
916 if (s.tag != TYPEVAR || !((TypeVar)s).isCaptured())
917 return false;
918 return isSameWildcard(t, ((CapturedType)s).wildcard);
919 }
921 public boolean isSameWildcard(WildcardType t, Type s) {
922 if (s.tag != WILDCARD)
923 return false;
924 WildcardType w = (WildcardType)s;
925 return w.kind == t.kind && w.type == t.type;
926 }
928 public boolean containsTypeEquivalent(List<Type> ts, List<Type> ss) {
929 while (ts.nonEmpty() && ss.nonEmpty()
930 && containsTypeEquivalent(ts.head, ss.head)) {
931 ts = ts.tail;
932 ss = ss.tail;
933 }
934 return ts.isEmpty() && ss.isEmpty();
935 }
936 // </editor-fold>
938 // <editor-fold defaultstate="collapsed" desc="isCastable">
939 public boolean isCastable(Type t, Type s) {
940 return isCastable(t, s, Warner.noWarnings);
941 }
943 /**
944 * Is t is castable to s?<br>
945 * s is assumed to be an erased type.<br>
946 * (not defined for Method and ForAll types).
947 */
948 public boolean isCastable(Type t, Type s, Warner warn) {
949 if (t == s)
950 return true;
952 if (t.isPrimitive() != s.isPrimitive())
953 return allowBoxing && (isConvertible(t, s, warn) || isConvertible(s, t, warn));
955 if (warn != warnStack.head) {
956 try {
957 warnStack = warnStack.prepend(warn);
958 checkUnsafeVarargsConversion(t, s, warn);
959 return isCastable.visit(t,s);
960 } finally {
961 warnStack = warnStack.tail;
962 }
963 } else {
964 return isCastable.visit(t,s);
965 }
966 }
967 // where
968 private TypeRelation isCastable = new TypeRelation() {
970 public Boolean visitType(Type t, Type s) {
971 if (s.tag == ERROR)
972 return true;
974 switch (t.tag) {
975 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
976 case DOUBLE:
977 return s.tag <= DOUBLE;
978 case BOOLEAN:
979 return s.tag == BOOLEAN;
980 case VOID:
981 return false;
982 case BOT:
983 return isSubtype(t, s);
984 default:
985 throw new AssertionError();
986 }
987 }
989 @Override
990 public Boolean visitWildcardType(WildcardType t, Type s) {
991 return isCastable(upperBound(t), s, warnStack.head);
992 }
994 @Override
995 public Boolean visitClassType(ClassType t, Type s) {
996 if (s.tag == ERROR || s.tag == BOT)
997 return true;
999 if (s.tag == TYPEVAR) {
1000 if (isCastable(t, s.getUpperBound(), Warner.noWarnings)) {
1001 warnStack.head.warn(LintCategory.UNCHECKED);
1002 return true;
1003 } else {
1004 return false;
1005 }
1006 }
1008 if (t.isCompound()) {
1009 Warner oldWarner = warnStack.head;
1010 warnStack.head = Warner.noWarnings;
1011 if (!visit(supertype(t), s))
1012 return false;
1013 for (Type intf : interfaces(t)) {
1014 if (!visit(intf, s))
1015 return false;
1016 }
1017 if (warnStack.head.hasLint(LintCategory.UNCHECKED))
1018 oldWarner.warn(LintCategory.UNCHECKED);
1019 return true;
1020 }
1022 if (s.isCompound()) {
1023 // call recursively to reuse the above code
1024 return visitClassType((ClassType)s, t);
1025 }
1027 if (s.tag == CLASS || s.tag == ARRAY) {
1028 boolean upcast;
1029 if ((upcast = isSubtype(erasure(t), erasure(s)))
1030 || isSubtype(erasure(s), erasure(t))) {
1031 if (!upcast && s.tag == ARRAY) {
1032 if (!isReifiable(s))
1033 warnStack.head.warn(LintCategory.UNCHECKED);
1034 return true;
1035 } else if (s.isRaw()) {
1036 return true;
1037 } else if (t.isRaw()) {
1038 if (!isUnbounded(s))
1039 warnStack.head.warn(LintCategory.UNCHECKED);
1040 return true;
1041 }
1042 // Assume |a| <: |b|
1043 final Type a = upcast ? t : s;
1044 final Type b = upcast ? s : t;
1045 final boolean HIGH = true;
1046 final boolean LOW = false;
1047 final boolean DONT_REWRITE_TYPEVARS = false;
1048 Type aHigh = rewriteQuantifiers(a, HIGH, DONT_REWRITE_TYPEVARS);
1049 Type aLow = rewriteQuantifiers(a, LOW, DONT_REWRITE_TYPEVARS);
1050 Type bHigh = rewriteQuantifiers(b, HIGH, DONT_REWRITE_TYPEVARS);
1051 Type bLow = rewriteQuantifiers(b, LOW, DONT_REWRITE_TYPEVARS);
1052 Type lowSub = asSub(bLow, aLow.tsym);
1053 Type highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
1054 if (highSub == null) {
1055 final boolean REWRITE_TYPEVARS = true;
1056 aHigh = rewriteQuantifiers(a, HIGH, REWRITE_TYPEVARS);
1057 aLow = rewriteQuantifiers(a, LOW, REWRITE_TYPEVARS);
1058 bHigh = rewriteQuantifiers(b, HIGH, REWRITE_TYPEVARS);
1059 bLow = rewriteQuantifiers(b, LOW, REWRITE_TYPEVARS);
1060 lowSub = asSub(bLow, aLow.tsym);
1061 highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
1062 }
1063 if (highSub != null) {
1064 assert a.tsym == highSub.tsym && a.tsym == lowSub.tsym
1065 : a.tsym + " != " + highSub.tsym + " != " + lowSub.tsym;
1066 if (!disjointTypes(aHigh.allparams(), highSub.allparams())
1067 && !disjointTypes(aHigh.allparams(), lowSub.allparams())
1068 && !disjointTypes(aLow.allparams(), highSub.allparams())
1069 && !disjointTypes(aLow.allparams(), lowSub.allparams())) {
1070 if (upcast ? giveWarning(a, b) :
1071 giveWarning(b, a))
1072 warnStack.head.warn(LintCategory.UNCHECKED);
1073 return true;
1074 }
1075 }
1076 if (isReifiable(s))
1077 return isSubtypeUnchecked(a, b);
1078 else
1079 return isSubtypeUnchecked(a, b, warnStack.head);
1080 }
1082 // Sidecast
1083 if (s.tag == CLASS) {
1084 if ((s.tsym.flags() & INTERFACE) != 0) {
1085 return ((t.tsym.flags() & FINAL) == 0)
1086 ? sideCast(t, s, warnStack.head)
1087 : sideCastFinal(t, s, warnStack.head);
1088 } else if ((t.tsym.flags() & INTERFACE) != 0) {
1089 return ((s.tsym.flags() & FINAL) == 0)
1090 ? sideCast(t, s, warnStack.head)
1091 : sideCastFinal(t, s, warnStack.head);
1092 } else {
1093 // unrelated class types
1094 return false;
1095 }
1096 }
1097 }
1098 return false;
1099 }
1101 @Override
1102 public Boolean visitArrayType(ArrayType t, Type s) {
1103 switch (s.tag) {
1104 case ERROR:
1105 case BOT:
1106 return true;
1107 case TYPEVAR:
1108 if (isCastable(s, t, Warner.noWarnings)) {
1109 warnStack.head.warn(LintCategory.UNCHECKED);
1110 return true;
1111 } else {
1112 return false;
1113 }
1114 case CLASS:
1115 return isSubtype(t, s);
1116 case ARRAY:
1117 if (elemtype(t).tag <= lastBaseTag ||
1118 elemtype(s).tag <= lastBaseTag) {
1119 return elemtype(t).tag == elemtype(s).tag;
1120 } else {
1121 return visit(elemtype(t), elemtype(s));
1122 }
1123 default:
1124 return false;
1125 }
1126 }
1128 @Override
1129 public Boolean visitTypeVar(TypeVar t, Type s) {
1130 switch (s.tag) {
1131 case ERROR:
1132 case BOT:
1133 return true;
1134 case TYPEVAR:
1135 if (isSubtype(t, s)) {
1136 return true;
1137 } else if (isCastable(t.bound, s, Warner.noWarnings)) {
1138 warnStack.head.warn(LintCategory.UNCHECKED);
1139 return true;
1140 } else {
1141 return false;
1142 }
1143 default:
1144 return isCastable(t.bound, s, warnStack.head);
1145 }
1146 }
1148 @Override
1149 public Boolean visitErrorType(ErrorType t, Type s) {
1150 return true;
1151 }
1152 };
1153 // </editor-fold>
1155 // <editor-fold defaultstate="collapsed" desc="disjointTypes">
1156 public boolean disjointTypes(List<Type> ts, List<Type> ss) {
1157 while (ts.tail != null && ss.tail != null) {
1158 if (disjointType(ts.head, ss.head)) return true;
1159 ts = ts.tail;
1160 ss = ss.tail;
1161 }
1162 return false;
1163 }
1165 /**
1166 * Two types or wildcards are considered disjoint if it can be
1167 * proven that no type can be contained in both. It is
1168 * conservative in that it is allowed to say that two types are
1169 * not disjoint, even though they actually are.
1170 *
1171 * The type C<X> is castable to C<Y> exactly if X and Y are not
1172 * disjoint.
1173 */
1174 public boolean disjointType(Type t, Type s) {
1175 return disjointType.visit(t, s);
1176 }
1177 // where
1178 private TypeRelation disjointType = new TypeRelation() {
1180 private Set<TypePair> cache = new HashSet<TypePair>();
1182 public Boolean visitType(Type t, Type s) {
1183 if (s.tag == WILDCARD)
1184 return visit(s, t);
1185 else
1186 return notSoftSubtypeRecursive(t, s) || notSoftSubtypeRecursive(s, t);
1187 }
1189 private boolean isCastableRecursive(Type t, Type s) {
1190 TypePair pair = new TypePair(t, s);
1191 if (cache.add(pair)) {
1192 try {
1193 return Types.this.isCastable(t, s);
1194 } finally {
1195 cache.remove(pair);
1196 }
1197 } else {
1198 return true;
1199 }
1200 }
1202 private boolean notSoftSubtypeRecursive(Type t, Type s) {
1203 TypePair pair = new TypePair(t, s);
1204 if (cache.add(pair)) {
1205 try {
1206 return Types.this.notSoftSubtype(t, s);
1207 } finally {
1208 cache.remove(pair);
1209 }
1210 } else {
1211 return false;
1212 }
1213 }
1215 @Override
1216 public Boolean visitWildcardType(WildcardType t, Type s) {
1217 if (t.isUnbound())
1218 return false;
1220 if (s.tag != WILDCARD) {
1221 if (t.isExtendsBound())
1222 return notSoftSubtypeRecursive(s, t.type);
1223 else // isSuperBound()
1224 return notSoftSubtypeRecursive(t.type, s);
1225 }
1227 if (s.isUnbound())
1228 return false;
1230 if (t.isExtendsBound()) {
1231 if (s.isExtendsBound())
1232 return !isCastableRecursive(t.type, upperBound(s));
1233 else if (s.isSuperBound())
1234 return notSoftSubtypeRecursive(lowerBound(s), t.type);
1235 } else if (t.isSuperBound()) {
1236 if (s.isExtendsBound())
1237 return notSoftSubtypeRecursive(t.type, upperBound(s));
1238 }
1239 return false;
1240 }
1241 };
1242 // </editor-fold>
1244 // <editor-fold defaultstate="collapsed" desc="lowerBoundArgtypes">
1245 /**
1246 * Returns the lower bounds of the formals of a method.
1247 */
1248 public List<Type> lowerBoundArgtypes(Type t) {
1249 return map(t.getParameterTypes(), lowerBoundMapping);
1250 }
1251 private final Mapping lowerBoundMapping = new Mapping("lowerBound") {
1252 public Type apply(Type t) {
1253 return lowerBound(t);
1254 }
1255 };
1256 // </editor-fold>
1258 // <editor-fold defaultstate="collapsed" desc="notSoftSubtype">
1259 /**
1260 * This relation answers the question: is impossible that
1261 * something of type `t' can be a subtype of `s'? This is
1262 * different from the question "is `t' not a subtype of `s'?"
1263 * when type variables are involved: Integer is not a subtype of T
1264 * where <T extends Number> but it is not true that Integer cannot
1265 * possibly be a subtype of T.
1266 */
1267 public boolean notSoftSubtype(Type t, Type s) {
1268 if (t == s) return false;
1269 if (t.tag == TYPEVAR) {
1270 TypeVar tv = (TypeVar) t;
1271 return !isCastable(tv.bound,
1272 relaxBound(s),
1273 Warner.noWarnings);
1274 }
1275 if (s.tag != WILDCARD)
1276 s = upperBound(s);
1278 return !isSubtype(t, relaxBound(s));
1279 }
1281 private Type relaxBound(Type t) {
1282 if (t.tag == TYPEVAR) {
1283 while (t.tag == TYPEVAR)
1284 t = t.getUpperBound();
1285 t = rewriteQuantifiers(t, true, true);
1286 }
1287 return t;
1288 }
1289 // </editor-fold>
1291 // <editor-fold defaultstate="collapsed" desc="isReifiable">
1292 public boolean isReifiable(Type t) {
1293 return isReifiable.visit(t);
1294 }
1295 // where
1296 private UnaryVisitor<Boolean> isReifiable = new UnaryVisitor<Boolean>() {
1298 public Boolean visitType(Type t, Void ignored) {
1299 return true;
1300 }
1302 @Override
1303 public Boolean visitClassType(ClassType t, Void ignored) {
1304 if (t.isCompound())
1305 return false;
1306 else {
1307 if (!t.isParameterized())
1308 return true;
1310 for (Type param : t.allparams()) {
1311 if (!param.isUnbound())
1312 return false;
1313 }
1314 return true;
1315 }
1316 }
1318 @Override
1319 public Boolean visitArrayType(ArrayType t, Void ignored) {
1320 return visit(t.elemtype);
1321 }
1323 @Override
1324 public Boolean visitTypeVar(TypeVar t, Void ignored) {
1325 return false;
1326 }
1327 };
1328 // </editor-fold>
1330 // <editor-fold defaultstate="collapsed" desc="Array Utils">
1331 public boolean isArray(Type t) {
1332 while (t.tag == WILDCARD)
1333 t = upperBound(t);
1334 return t.tag == ARRAY;
1335 }
1337 /**
1338 * The element type of an array.
1339 */
1340 public Type elemtype(Type t) {
1341 switch (t.tag) {
1342 case WILDCARD:
1343 return elemtype(upperBound(t));
1344 case ARRAY:
1345 return ((ArrayType)t).elemtype;
1346 case FORALL:
1347 return elemtype(((ForAll)t).qtype);
1348 case ERROR:
1349 return t;
1350 default:
1351 return null;
1352 }
1353 }
1355 public Type elemtypeOrType(Type t) {
1356 Type elemtype = elemtype(t);
1357 return elemtype != null ?
1358 elemtype :
1359 t;
1360 }
1362 /**
1363 * Mapping to take element type of an arraytype
1364 */
1365 private Mapping elemTypeFun = new Mapping ("elemTypeFun") {
1366 public Type apply(Type t) { return elemtype(t); }
1367 };
1369 /**
1370 * The number of dimensions of an array type.
1371 */
1372 public int dimensions(Type t) {
1373 int result = 0;
1374 while (t.tag == ARRAY) {
1375 result++;
1376 t = elemtype(t);
1377 }
1378 return result;
1379 }
1380 // </editor-fold>
1382 // <editor-fold defaultstate="collapsed" desc="asSuper">
1383 /**
1384 * Return the (most specific) base type of t that starts with the
1385 * given symbol. If none exists, return null.
1386 *
1387 * @param t a type
1388 * @param sym a symbol
1389 */
1390 public Type asSuper(Type t, Symbol sym) {
1391 return asSuper.visit(t, sym);
1392 }
1393 // where
1394 private SimpleVisitor<Type,Symbol> asSuper = new SimpleVisitor<Type,Symbol>() {
1396 public Type visitType(Type t, Symbol sym) {
1397 return null;
1398 }
1400 @Override
1401 public Type visitClassType(ClassType t, Symbol sym) {
1402 if (t.tsym == sym)
1403 return t;
1405 Type st = supertype(t);
1406 if (st.tag == CLASS || st.tag == TYPEVAR || st.tag == ERROR) {
1407 Type x = asSuper(st, sym);
1408 if (x != null)
1409 return x;
1410 }
1411 if ((sym.flags() & INTERFACE) != 0) {
1412 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
1413 Type x = asSuper(l.head, sym);
1414 if (x != null)
1415 return x;
1416 }
1417 }
1418 return null;
1419 }
1421 @Override
1422 public Type visitArrayType(ArrayType t, Symbol sym) {
1423 return isSubtype(t, sym.type) ? sym.type : null;
1424 }
1426 @Override
1427 public Type visitTypeVar(TypeVar t, Symbol sym) {
1428 if (t.tsym == sym)
1429 return t;
1430 else
1431 return asSuper(t.bound, sym);
1432 }
1434 @Override
1435 public Type visitErrorType(ErrorType t, Symbol sym) {
1436 return t;
1437 }
1438 };
1440 /**
1441 * Return the base type of t or any of its outer types that starts
1442 * with the given symbol. If none exists, return null.
1443 *
1444 * @param t a type
1445 * @param sym a symbol
1446 */
1447 public Type asOuterSuper(Type t, Symbol sym) {
1448 switch (t.tag) {
1449 case CLASS:
1450 do {
1451 Type s = asSuper(t, sym);
1452 if (s != null) return s;
1453 t = t.getEnclosingType();
1454 } while (t.tag == CLASS);
1455 return null;
1456 case ARRAY:
1457 return isSubtype(t, sym.type) ? sym.type : null;
1458 case TYPEVAR:
1459 return asSuper(t, sym);
1460 case ERROR:
1461 return t;
1462 default:
1463 return null;
1464 }
1465 }
1467 /**
1468 * Return the base type of t or any of its enclosing types that
1469 * starts with the given symbol. If none exists, return null.
1470 *
1471 * @param t a type
1472 * @param sym a symbol
1473 */
1474 public Type asEnclosingSuper(Type t, Symbol sym) {
1475 switch (t.tag) {
1476 case CLASS:
1477 do {
1478 Type s = asSuper(t, sym);
1479 if (s != null) return s;
1480 Type outer = t.getEnclosingType();
1481 t = (outer.tag == CLASS) ? outer :
1482 (t.tsym.owner.enclClass() != null) ? t.tsym.owner.enclClass().type :
1483 Type.noType;
1484 } while (t.tag == CLASS);
1485 return null;
1486 case ARRAY:
1487 return isSubtype(t, sym.type) ? sym.type : null;
1488 case TYPEVAR:
1489 return asSuper(t, sym);
1490 case ERROR:
1491 return t;
1492 default:
1493 return null;
1494 }
1495 }
1496 // </editor-fold>
1498 // <editor-fold defaultstate="collapsed" desc="memberType">
1499 /**
1500 * The type of given symbol, seen as a member of t.
1501 *
1502 * @param t a type
1503 * @param sym a symbol
1504 */
1505 public Type memberType(Type t, Symbol sym) {
1506 return (sym.flags() & STATIC) != 0
1507 ? sym.type
1508 : memberType.visit(t, sym);
1509 }
1510 // where
1511 private SimpleVisitor<Type,Symbol> memberType = new SimpleVisitor<Type,Symbol>() {
1513 public Type visitType(Type t, Symbol sym) {
1514 return sym.type;
1515 }
1517 @Override
1518 public Type visitWildcardType(WildcardType t, Symbol sym) {
1519 return memberType(upperBound(t), sym);
1520 }
1522 @Override
1523 public Type visitClassType(ClassType t, Symbol sym) {
1524 Symbol owner = sym.owner;
1525 long flags = sym.flags();
1526 if (((flags & STATIC) == 0) && owner.type.isParameterized()) {
1527 Type base = asOuterSuper(t, owner);
1528 //if t is an intersection type T = CT & I1 & I2 ... & In
1529 //its supertypes CT, I1, ... In might contain wildcards
1530 //so we need to go through capture conversion
1531 base = t.isCompound() ? capture(base) : base;
1532 if (base != null) {
1533 List<Type> ownerParams = owner.type.allparams();
1534 List<Type> baseParams = base.allparams();
1535 if (ownerParams.nonEmpty()) {
1536 if (baseParams.isEmpty()) {
1537 // then base is a raw type
1538 return erasure(sym.type);
1539 } else {
1540 return subst(sym.type, ownerParams, baseParams);
1541 }
1542 }
1543 }
1544 }
1545 return sym.type;
1546 }
1548 @Override
1549 public Type visitTypeVar(TypeVar t, Symbol sym) {
1550 return memberType(t.bound, sym);
1551 }
1553 @Override
1554 public Type visitErrorType(ErrorType t, Symbol sym) {
1555 return t;
1556 }
1557 };
1558 // </editor-fold>
1560 // <editor-fold defaultstate="collapsed" desc="isAssignable">
1561 public boolean isAssignable(Type t, Type s) {
1562 return isAssignable(t, s, Warner.noWarnings);
1563 }
1565 /**
1566 * Is t assignable to s?<br>
1567 * Equivalent to subtype except for constant values and raw
1568 * types.<br>
1569 * (not defined for Method and ForAll types)
1570 */
1571 public boolean isAssignable(Type t, Type s, Warner warn) {
1572 if (t.tag == ERROR)
1573 return true;
1574 if (t.tag <= INT && t.constValue() != null) {
1575 int value = ((Number)t.constValue()).intValue();
1576 switch (s.tag) {
1577 case BYTE:
1578 if (Byte.MIN_VALUE <= value && value <= Byte.MAX_VALUE)
1579 return true;
1580 break;
1581 case CHAR:
1582 if (Character.MIN_VALUE <= value && value <= Character.MAX_VALUE)
1583 return true;
1584 break;
1585 case SHORT:
1586 if (Short.MIN_VALUE <= value && value <= Short.MAX_VALUE)
1587 return true;
1588 break;
1589 case INT:
1590 return true;
1591 case CLASS:
1592 switch (unboxedType(s).tag) {
1593 case BYTE:
1594 case CHAR:
1595 case SHORT:
1596 return isAssignable(t, unboxedType(s), warn);
1597 }
1598 break;
1599 }
1600 }
1601 return isConvertible(t, s, warn);
1602 }
1603 // </editor-fold>
1605 // <editor-fold defaultstate="collapsed" desc="erasure">
1606 /**
1607 * The erasure of t {@code |t|} -- the type that results when all
1608 * type parameters in t are deleted.
1609 */
1610 public Type erasure(Type t) {
1611 return erasure(t, false);
1612 }
1613 //where
1614 private Type erasure(Type t, boolean recurse) {
1615 if (t.tag <= lastBaseTag)
1616 return t; /* fast special case */
1617 else
1618 return erasure.visit(t, recurse);
1619 }
1620 // where
1621 private SimpleVisitor<Type, Boolean> erasure = new SimpleVisitor<Type, Boolean>() {
1622 public Type visitType(Type t, Boolean recurse) {
1623 if (t.tag <= lastBaseTag)
1624 return t; /*fast special case*/
1625 else
1626 return t.map(recurse ? erasureRecFun : erasureFun);
1627 }
1629 @Override
1630 public Type visitWildcardType(WildcardType t, Boolean recurse) {
1631 return erasure(upperBound(t), recurse);
1632 }
1634 @Override
1635 public Type visitClassType(ClassType t, Boolean recurse) {
1636 Type erased = t.tsym.erasure(Types.this);
1637 if (recurse) {
1638 erased = new ErasedClassType(erased.getEnclosingType(),erased.tsym);
1639 }
1640 return erased;
1641 }
1643 @Override
1644 public Type visitTypeVar(TypeVar t, Boolean recurse) {
1645 return erasure(t.bound, recurse);
1646 }
1648 @Override
1649 public Type visitErrorType(ErrorType t, Boolean recurse) {
1650 return t;
1651 }
1652 };
1654 private Mapping erasureFun = new Mapping ("erasure") {
1655 public Type apply(Type t) { return erasure(t); }
1656 };
1658 private Mapping erasureRecFun = new Mapping ("erasureRecursive") {
1659 public Type apply(Type t) { return erasureRecursive(t); }
1660 };
1662 public List<Type> erasure(List<Type> ts) {
1663 return Type.map(ts, erasureFun);
1664 }
1666 public Type erasureRecursive(Type t) {
1667 return erasure(t, true);
1668 }
1670 public List<Type> erasureRecursive(List<Type> ts) {
1671 return Type.map(ts, erasureRecFun);
1672 }
1673 // </editor-fold>
1675 // <editor-fold defaultstate="collapsed" desc="makeCompoundType">
1676 /**
1677 * Make a compound type from non-empty list of types
1678 *
1679 * @param bounds the types from which the compound type is formed
1680 * @param supertype is objectType if all bounds are interfaces,
1681 * null otherwise.
1682 */
1683 public Type makeCompoundType(List<Type> bounds,
1684 Type supertype) {
1685 ClassSymbol bc =
1686 new ClassSymbol(ABSTRACT|PUBLIC|SYNTHETIC|COMPOUND|ACYCLIC,
1687 Type.moreInfo
1688 ? names.fromString(bounds.toString())
1689 : names.empty,
1690 syms.noSymbol);
1691 if (bounds.head.tag == TYPEVAR)
1692 // error condition, recover
1693 bc.erasure_field = syms.objectType;
1694 else
1695 bc.erasure_field = erasure(bounds.head);
1696 bc.members_field = new Scope(bc);
1697 ClassType bt = (ClassType)bc.type;
1698 bt.allparams_field = List.nil();
1699 if (supertype != null) {
1700 bt.supertype_field = supertype;
1701 bt.interfaces_field = bounds;
1702 } else {
1703 bt.supertype_field = bounds.head;
1704 bt.interfaces_field = bounds.tail;
1705 }
1706 assert bt.supertype_field.tsym.completer != null
1707 || !bt.supertype_field.isInterface()
1708 : bt.supertype_field;
1709 return bt;
1710 }
1712 /**
1713 * Same as {@link #makeCompoundType(List,Type)}, except that the
1714 * second parameter is computed directly. Note that this might
1715 * cause a symbol completion. Hence, this version of
1716 * makeCompoundType may not be called during a classfile read.
1717 */
1718 public Type makeCompoundType(List<Type> bounds) {
1719 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1720 supertype(bounds.head) : null;
1721 return makeCompoundType(bounds, supertype);
1722 }
1724 /**
1725 * A convenience wrapper for {@link #makeCompoundType(List)}; the
1726 * arguments are converted to a list and passed to the other
1727 * method. Note that this might cause a symbol completion.
1728 * Hence, this version of makeCompoundType may not be called
1729 * during a classfile read.
1730 */
1731 public Type makeCompoundType(Type bound1, Type bound2) {
1732 return makeCompoundType(List.of(bound1, bound2));
1733 }
1734 // </editor-fold>
1736 // <editor-fold defaultstate="collapsed" desc="supertype">
1737 public Type supertype(Type t) {
1738 return supertype.visit(t);
1739 }
1740 // where
1741 private UnaryVisitor<Type> supertype = new UnaryVisitor<Type>() {
1743 public Type visitType(Type t, Void ignored) {
1744 // A note on wildcards: there is no good way to
1745 // determine a supertype for a super bounded wildcard.
1746 return null;
1747 }
1749 @Override
1750 public Type visitClassType(ClassType t, Void ignored) {
1751 if (t.supertype_field == null) {
1752 Type supertype = ((ClassSymbol)t.tsym).getSuperclass();
1753 // An interface has no superclass; its supertype is Object.
1754 if (t.isInterface())
1755 supertype = ((ClassType)t.tsym.type).supertype_field;
1756 if (t.supertype_field == null) {
1757 List<Type> actuals = classBound(t).allparams();
1758 List<Type> formals = t.tsym.type.allparams();
1759 if (t.hasErasedSupertypes()) {
1760 t.supertype_field = erasureRecursive(supertype);
1761 } else if (formals.nonEmpty()) {
1762 t.supertype_field = subst(supertype, formals, actuals);
1763 }
1764 else {
1765 t.supertype_field = supertype;
1766 }
1767 }
1768 }
1769 return t.supertype_field;
1770 }
1772 /**
1773 * The supertype is always a class type. If the type
1774 * variable's bounds start with a class type, this is also
1775 * the supertype. Otherwise, the supertype is
1776 * java.lang.Object.
1777 */
1778 @Override
1779 public Type visitTypeVar(TypeVar t, Void ignored) {
1780 if (t.bound.tag == TYPEVAR ||
1781 (!t.bound.isCompound() && !t.bound.isInterface())) {
1782 return t.bound;
1783 } else {
1784 return supertype(t.bound);
1785 }
1786 }
1788 @Override
1789 public Type visitArrayType(ArrayType t, Void ignored) {
1790 if (t.elemtype.isPrimitive() || isSameType(t.elemtype, syms.objectType))
1791 return arraySuperType();
1792 else
1793 return new ArrayType(supertype(t.elemtype), t.tsym);
1794 }
1796 @Override
1797 public Type visitErrorType(ErrorType t, Void ignored) {
1798 return t;
1799 }
1800 };
1801 // </editor-fold>
1803 // <editor-fold defaultstate="collapsed" desc="interfaces">
1804 /**
1805 * Return the interfaces implemented by this class.
1806 */
1807 public List<Type> interfaces(Type t) {
1808 return interfaces.visit(t);
1809 }
1810 // where
1811 private UnaryVisitor<List<Type>> interfaces = new UnaryVisitor<List<Type>>() {
1813 public List<Type> visitType(Type t, Void ignored) {
1814 return List.nil();
1815 }
1817 @Override
1818 public List<Type> visitClassType(ClassType t, Void ignored) {
1819 if (t.interfaces_field == null) {
1820 List<Type> interfaces = ((ClassSymbol)t.tsym).getInterfaces();
1821 if (t.interfaces_field == null) {
1822 // If t.interfaces_field is null, then t must
1823 // be a parameterized type (not to be confused
1824 // with a generic type declaration).
1825 // Terminology:
1826 // Parameterized type: List<String>
1827 // Generic type declaration: class List<E> { ... }
1828 // So t corresponds to List<String> and
1829 // t.tsym.type corresponds to List<E>.
1830 // The reason t must be parameterized type is
1831 // that completion will happen as a side
1832 // effect of calling
1833 // ClassSymbol.getInterfaces. Since
1834 // t.interfaces_field is null after
1835 // completion, we can assume that t is not the
1836 // type of a class/interface declaration.
1837 assert t != t.tsym.type : t.toString();
1838 List<Type> actuals = t.allparams();
1839 List<Type> formals = t.tsym.type.allparams();
1840 if (t.hasErasedSupertypes()) {
1841 t.interfaces_field = erasureRecursive(interfaces);
1842 } else if (formals.nonEmpty()) {
1843 t.interfaces_field =
1844 upperBounds(subst(interfaces, formals, actuals));
1845 }
1846 else {
1847 t.interfaces_field = interfaces;
1848 }
1849 }
1850 }
1851 return t.interfaces_field;
1852 }
1854 @Override
1855 public List<Type> visitTypeVar(TypeVar t, Void ignored) {
1856 if (t.bound.isCompound())
1857 return interfaces(t.bound);
1859 if (t.bound.isInterface())
1860 return List.of(t.bound);
1862 return List.nil();
1863 }
1864 };
1865 // </editor-fold>
1867 // <editor-fold defaultstate="collapsed" desc="isDerivedRaw">
1868 Map<Type,Boolean> isDerivedRawCache = new HashMap<Type,Boolean>();
1870 public boolean isDerivedRaw(Type t) {
1871 Boolean result = isDerivedRawCache.get(t);
1872 if (result == null) {
1873 result = isDerivedRawInternal(t);
1874 isDerivedRawCache.put(t, result);
1875 }
1876 return result;
1877 }
1879 public boolean isDerivedRawInternal(Type t) {
1880 if (t.isErroneous())
1881 return false;
1882 return
1883 t.isRaw() ||
1884 supertype(t) != null && isDerivedRaw(supertype(t)) ||
1885 isDerivedRaw(interfaces(t));
1886 }
1888 public boolean isDerivedRaw(List<Type> ts) {
1889 List<Type> l = ts;
1890 while (l.nonEmpty() && !isDerivedRaw(l.head)) l = l.tail;
1891 return l.nonEmpty();
1892 }
1893 // </editor-fold>
1895 // <editor-fold defaultstate="collapsed" desc="setBounds">
1896 /**
1897 * Set the bounds field of the given type variable to reflect a
1898 * (possibly multiple) list of bounds.
1899 * @param t a type variable
1900 * @param bounds the bounds, must be nonempty
1901 * @param supertype is objectType if all bounds are interfaces,
1902 * null otherwise.
1903 */
1904 public void setBounds(TypeVar t, List<Type> bounds, Type supertype) {
1905 if (bounds.tail.isEmpty())
1906 t.bound = bounds.head;
1907 else
1908 t.bound = makeCompoundType(bounds, supertype);
1909 t.rank_field = -1;
1910 }
1912 /**
1913 * Same as {@link #setBounds(Type.TypeVar,List,Type)}, except that
1914 * third parameter is computed directly, as follows: if all
1915 * all bounds are interface types, the computed supertype is Object,
1916 * otherwise the supertype is simply left null (in this case, the supertype
1917 * is assumed to be the head of the bound list passed as second argument).
1918 * Note that this check might cause a symbol completion. Hence, this version of
1919 * setBounds may not be called during a classfile read.
1920 */
1921 public void setBounds(TypeVar t, List<Type> bounds) {
1922 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1923 syms.objectType : null;
1924 setBounds(t, bounds, supertype);
1925 t.rank_field = -1;
1926 }
1927 // </editor-fold>
1929 // <editor-fold defaultstate="collapsed" desc="getBounds">
1930 /**
1931 * Return list of bounds of the given type variable.
1932 */
1933 public List<Type> getBounds(TypeVar t) {
1934 if (t.bound.isErroneous() || !t.bound.isCompound())
1935 return List.of(t.bound);
1936 else if ((erasure(t).tsym.flags() & INTERFACE) == 0)
1937 return interfaces(t).prepend(supertype(t));
1938 else
1939 // No superclass was given in bounds.
1940 // In this case, supertype is Object, erasure is first interface.
1941 return interfaces(t);
1942 }
1943 // </editor-fold>
1945 // <editor-fold defaultstate="collapsed" desc="classBound">
1946 /**
1947 * If the given type is a (possibly selected) type variable,
1948 * return the bounding class of this type, otherwise return the
1949 * type itself.
1950 */
1951 public Type classBound(Type t) {
1952 return classBound.visit(t);
1953 }
1954 // where
1955 private UnaryVisitor<Type> classBound = new UnaryVisitor<Type>() {
1957 public Type visitType(Type t, Void ignored) {
1958 return t;
1959 }
1961 @Override
1962 public Type visitClassType(ClassType t, Void ignored) {
1963 Type outer1 = classBound(t.getEnclosingType());
1964 if (outer1 != t.getEnclosingType())
1965 return new ClassType(outer1, t.getTypeArguments(), t.tsym);
1966 else
1967 return t;
1968 }
1970 @Override
1971 public Type visitTypeVar(TypeVar t, Void ignored) {
1972 return classBound(supertype(t));
1973 }
1975 @Override
1976 public Type visitErrorType(ErrorType t, Void ignored) {
1977 return t;
1978 }
1979 };
1980 // </editor-fold>
1982 // <editor-fold defaultstate="collapsed" desc="sub signature / override equivalence">
1983 /**
1984 * Returns true iff the first signature is a <em>sub
1985 * signature</em> of the other. This is <b>not</b> an equivalence
1986 * relation.
1987 *
1988 * @see "The Java Language Specification, Third Ed. (8.4.2)."
1989 * @see #overrideEquivalent(Type t, Type s)
1990 * @param t first signature (possibly raw).
1991 * @param s second signature (could be subjected to erasure).
1992 * @return true if t is a sub signature of s.
1993 */
1994 public boolean isSubSignature(Type t, Type s) {
1995 return hasSameArgs(t, s) || hasSameArgs(t, erasure(s));
1996 }
1998 /**
1999 * Returns true iff these signatures are related by <em>override
2000 * equivalence</em>. This is the natural extension of
2001 * isSubSignature to an equivalence relation.
2002 *
2003 * @see "The Java Language Specification, Third Ed. (8.4.2)."
2004 * @see #isSubSignature(Type t, Type s)
2005 * @param t a signature (possible raw, could be subjected to
2006 * erasure).
2007 * @param s a signature (possible raw, could be subjected to
2008 * erasure).
2009 * @return true if either argument is a sub signature of the other.
2010 */
2011 public boolean overrideEquivalent(Type t, Type s) {
2012 return hasSameArgs(t, s) ||
2013 hasSameArgs(t, erasure(s)) || hasSameArgs(erasure(t), s);
2014 }
2016 // <editor-fold defaultstate="collapsed" desc="Determining method implementation in given site">
2017 class ImplementationCache {
2019 private WeakHashMap<MethodSymbol, SoftReference<Map<TypeSymbol, Entry>>> _map =
2020 new WeakHashMap<MethodSymbol, SoftReference<Map<TypeSymbol, Entry>>>();
2022 class Entry {
2023 final MethodSymbol cachedImpl;
2024 final Filter<Symbol> implFilter;
2025 final boolean checkResult;
2026 final Scope.ScopeCounter scopeCounter;
2028 public Entry(MethodSymbol cachedImpl,
2029 Filter<Symbol> scopeFilter,
2030 boolean checkResult,
2031 Scope.ScopeCounter scopeCounter) {
2032 this.cachedImpl = cachedImpl;
2033 this.implFilter = scopeFilter;
2034 this.checkResult = checkResult;
2035 this.scopeCounter = scopeCounter;
2036 }
2038 boolean matches(Filter<Symbol> scopeFilter, boolean checkResult, Scope.ScopeCounter scopeCounter) {
2039 return this.implFilter == scopeFilter &&
2040 this.checkResult == checkResult &&
2041 this.scopeCounter.val() >= scopeCounter.val();
2042 }
2043 }
2045 MethodSymbol get(MethodSymbol ms, TypeSymbol origin, boolean checkResult, Filter<Symbol> implFilter, Scope.ScopeCounter scopeCounter) {
2046 SoftReference<Map<TypeSymbol, Entry>> ref_cache = _map.get(ms);
2047 Map<TypeSymbol, Entry> cache = ref_cache != null ? ref_cache.get() : null;
2048 if (cache == null) {
2049 cache = new HashMap<TypeSymbol, Entry>();
2050 _map.put(ms, new SoftReference<Map<TypeSymbol, Entry>>(cache));
2051 }
2052 Entry e = cache.get(origin);
2053 if (e == null ||
2054 !e.matches(implFilter, checkResult, scopeCounter)) {
2055 MethodSymbol impl = implementationInternal(ms, origin, Types.this, checkResult, implFilter);
2056 cache.put(origin, new Entry(impl, implFilter, checkResult, scopeCounter));
2057 return impl;
2058 }
2059 else {
2060 return e.cachedImpl;
2061 }
2062 }
2064 private MethodSymbol implementationInternal(MethodSymbol ms, TypeSymbol origin, Types types, boolean checkResult, Filter<Symbol> implFilter) {
2065 for (Type t = origin.type; t.tag == CLASS || t.tag == TYPEVAR; t = types.supertype(t)) {
2066 while (t.tag == TYPEVAR)
2067 t = t.getUpperBound();
2068 TypeSymbol c = t.tsym;
2069 for (Scope.Entry e = c.members().lookup(ms.name, implFilter);
2070 e.scope != null;
2071 e = e.next(implFilter)) {
2072 if (e.sym != null &&
2073 e.sym.overrides(ms, origin, types, checkResult))
2074 return (MethodSymbol)e.sym;
2075 }
2076 }
2077 return null;
2078 }
2079 }
2081 private ImplementationCache implCache = new ImplementationCache();
2083 public MethodSymbol implementation(MethodSymbol ms, TypeSymbol origin, Types types, boolean checkResult, Filter<Symbol> implFilter) {
2084 return implCache.get(ms, origin, checkResult, implFilter, scopeCounter);
2085 }
2086 // </editor-fold>
2088 /**
2089 * Does t have the same arguments as s? It is assumed that both
2090 * types are (possibly polymorphic) method types. Monomorphic
2091 * method types "have the same arguments", if their argument lists
2092 * are equal. Polymorphic method types "have the same arguments",
2093 * if they have the same arguments after renaming all type
2094 * variables of one to corresponding type variables in the other,
2095 * where correspondence is by position in the type parameter list.
2096 */
2097 public boolean hasSameArgs(Type t, Type s) {
2098 return hasSameArgs.visit(t, s);
2099 }
2100 // where
2101 private TypeRelation hasSameArgs = new TypeRelation() {
2103 public Boolean visitType(Type t, Type s) {
2104 throw new AssertionError();
2105 }
2107 @Override
2108 public Boolean visitMethodType(MethodType t, Type s) {
2109 return s.tag == METHOD
2110 && containsTypeEquivalent(t.argtypes, s.getParameterTypes());
2111 }
2113 @Override
2114 public Boolean visitForAll(ForAll t, Type s) {
2115 if (s.tag != FORALL)
2116 return false;
2118 ForAll forAll = (ForAll)s;
2119 return hasSameBounds(t, forAll)
2120 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
2121 }
2123 @Override
2124 public Boolean visitErrorType(ErrorType t, Type s) {
2125 return false;
2126 }
2127 };
2128 // </editor-fold>
2130 // <editor-fold defaultstate="collapsed" desc="subst">
2131 public List<Type> subst(List<Type> ts,
2132 List<Type> from,
2133 List<Type> to) {
2134 return new Subst(from, to).subst(ts);
2135 }
2137 /**
2138 * Substitute all occurrences of a type in `from' with the
2139 * corresponding type in `to' in 't'. Match lists `from' and `to'
2140 * from the right: If lists have different length, discard leading
2141 * elements of the longer list.
2142 */
2143 public Type subst(Type t, List<Type> from, List<Type> to) {
2144 return new Subst(from, to).subst(t);
2145 }
2147 private class Subst extends UnaryVisitor<Type> {
2148 List<Type> from;
2149 List<Type> to;
2151 public Subst(List<Type> from, List<Type> to) {
2152 int fromLength = from.length();
2153 int toLength = to.length();
2154 while (fromLength > toLength) {
2155 fromLength--;
2156 from = from.tail;
2157 }
2158 while (fromLength < toLength) {
2159 toLength--;
2160 to = to.tail;
2161 }
2162 this.from = from;
2163 this.to = to;
2164 }
2166 Type subst(Type t) {
2167 if (from.tail == null)
2168 return t;
2169 else
2170 return visit(t);
2171 }
2173 List<Type> subst(List<Type> ts) {
2174 if (from.tail == null)
2175 return ts;
2176 boolean wild = false;
2177 if (ts.nonEmpty() && from.nonEmpty()) {
2178 Type head1 = subst(ts.head);
2179 List<Type> tail1 = subst(ts.tail);
2180 if (head1 != ts.head || tail1 != ts.tail)
2181 return tail1.prepend(head1);
2182 }
2183 return ts;
2184 }
2186 public Type visitType(Type t, Void ignored) {
2187 return t;
2188 }
2190 @Override
2191 public Type visitMethodType(MethodType t, Void ignored) {
2192 List<Type> argtypes = subst(t.argtypes);
2193 Type restype = subst(t.restype);
2194 List<Type> thrown = subst(t.thrown);
2195 if (argtypes == t.argtypes &&
2196 restype == t.restype &&
2197 thrown == t.thrown)
2198 return t;
2199 else
2200 return new MethodType(argtypes, restype, thrown, t.tsym);
2201 }
2203 @Override
2204 public Type visitTypeVar(TypeVar t, Void ignored) {
2205 for (List<Type> from = this.from, to = this.to;
2206 from.nonEmpty();
2207 from = from.tail, to = to.tail) {
2208 if (t == from.head) {
2209 return to.head.withTypeVar(t);
2210 }
2211 }
2212 return t;
2213 }
2215 @Override
2216 public Type visitClassType(ClassType t, Void ignored) {
2217 if (!t.isCompound()) {
2218 List<Type> typarams = t.getTypeArguments();
2219 List<Type> typarams1 = subst(typarams);
2220 Type outer = t.getEnclosingType();
2221 Type outer1 = subst(outer);
2222 if (typarams1 == typarams && outer1 == outer)
2223 return t;
2224 else
2225 return new ClassType(outer1, typarams1, t.tsym);
2226 } else {
2227 Type st = subst(supertype(t));
2228 List<Type> is = upperBounds(subst(interfaces(t)));
2229 if (st == supertype(t) && is == interfaces(t))
2230 return t;
2231 else
2232 return makeCompoundType(is.prepend(st));
2233 }
2234 }
2236 @Override
2237 public Type visitWildcardType(WildcardType t, Void ignored) {
2238 Type bound = t.type;
2239 if (t.kind != BoundKind.UNBOUND)
2240 bound = subst(bound);
2241 if (bound == t.type) {
2242 return t;
2243 } else {
2244 if (t.isExtendsBound() && bound.isExtendsBound())
2245 bound = upperBound(bound);
2246 return new WildcardType(bound, t.kind, syms.boundClass, t.bound);
2247 }
2248 }
2250 @Override
2251 public Type visitArrayType(ArrayType t, Void ignored) {
2252 Type elemtype = subst(t.elemtype);
2253 if (elemtype == t.elemtype)
2254 return t;
2255 else
2256 return new ArrayType(upperBound(elemtype), t.tsym);
2257 }
2259 @Override
2260 public Type visitForAll(ForAll t, Void ignored) {
2261 List<Type> tvars1 = substBounds(t.tvars, from, to);
2262 Type qtype1 = subst(t.qtype);
2263 if (tvars1 == t.tvars && qtype1 == t.qtype) {
2264 return t;
2265 } else if (tvars1 == t.tvars) {
2266 return new ForAll(tvars1, qtype1);
2267 } else {
2268 return new ForAll(tvars1, Types.this.subst(qtype1, t.tvars, tvars1));
2269 }
2270 }
2272 @Override
2273 public Type visitErrorType(ErrorType t, Void ignored) {
2274 return t;
2275 }
2276 }
2278 public List<Type> substBounds(List<Type> tvars,
2279 List<Type> from,
2280 List<Type> to) {
2281 if (tvars.isEmpty())
2282 return tvars;
2283 ListBuffer<Type> newBoundsBuf = lb();
2284 boolean changed = false;
2285 // calculate new bounds
2286 for (Type t : tvars) {
2287 TypeVar tv = (TypeVar) t;
2288 Type bound = subst(tv.bound, from, to);
2289 if (bound != tv.bound)
2290 changed = true;
2291 newBoundsBuf.append(bound);
2292 }
2293 if (!changed)
2294 return tvars;
2295 ListBuffer<Type> newTvars = lb();
2296 // create new type variables without bounds
2297 for (Type t : tvars) {
2298 newTvars.append(new TypeVar(t.tsym, null, syms.botType));
2299 }
2300 // the new bounds should use the new type variables in place
2301 // of the old
2302 List<Type> newBounds = newBoundsBuf.toList();
2303 from = tvars;
2304 to = newTvars.toList();
2305 for (; !newBounds.isEmpty(); newBounds = newBounds.tail) {
2306 newBounds.head = subst(newBounds.head, from, to);
2307 }
2308 newBounds = newBoundsBuf.toList();
2309 // set the bounds of new type variables to the new bounds
2310 for (Type t : newTvars.toList()) {
2311 TypeVar tv = (TypeVar) t;
2312 tv.bound = newBounds.head;
2313 newBounds = newBounds.tail;
2314 }
2315 return newTvars.toList();
2316 }
2318 public TypeVar substBound(TypeVar t, List<Type> from, List<Type> to) {
2319 Type bound1 = subst(t.bound, from, to);
2320 if (bound1 == t.bound)
2321 return t;
2322 else {
2323 // create new type variable without bounds
2324 TypeVar tv = new TypeVar(t.tsym, null, syms.botType);
2325 // the new bound should use the new type variable in place
2326 // of the old
2327 tv.bound = subst(bound1, List.<Type>of(t), List.<Type>of(tv));
2328 return tv;
2329 }
2330 }
2331 // </editor-fold>
2333 // <editor-fold defaultstate="collapsed" desc="hasSameBounds">
2334 /**
2335 * Does t have the same bounds for quantified variables as s?
2336 */
2337 boolean hasSameBounds(ForAll t, ForAll s) {
2338 List<Type> l1 = t.tvars;
2339 List<Type> l2 = s.tvars;
2340 while (l1.nonEmpty() && l2.nonEmpty() &&
2341 isSameType(l1.head.getUpperBound(),
2342 subst(l2.head.getUpperBound(),
2343 s.tvars,
2344 t.tvars))) {
2345 l1 = l1.tail;
2346 l2 = l2.tail;
2347 }
2348 return l1.isEmpty() && l2.isEmpty();
2349 }
2350 // </editor-fold>
2352 // <editor-fold defaultstate="collapsed" desc="newInstances">
2353 /** Create new vector of type variables from list of variables
2354 * changing all recursive bounds from old to new list.
2355 */
2356 public List<Type> newInstances(List<Type> tvars) {
2357 List<Type> tvars1 = Type.map(tvars, newInstanceFun);
2358 for (List<Type> l = tvars1; l.nonEmpty(); l = l.tail) {
2359 TypeVar tv = (TypeVar) l.head;
2360 tv.bound = subst(tv.bound, tvars, tvars1);
2361 }
2362 return tvars1;
2363 }
2364 static private Mapping newInstanceFun = new Mapping("newInstanceFun") {
2365 public Type apply(Type t) { return new TypeVar(t.tsym, t.getUpperBound(), t.getLowerBound()); }
2366 };
2367 // </editor-fold>
2369 // <editor-fold defaultstate="collapsed" desc="createErrorType">
2370 public Type createErrorType(Type originalType) {
2371 return new ErrorType(originalType, syms.errSymbol);
2372 }
2374 public Type createErrorType(ClassSymbol c, Type originalType) {
2375 return new ErrorType(c, originalType);
2376 }
2378 public Type createErrorType(Name name, TypeSymbol container, Type originalType) {
2379 return new ErrorType(name, container, originalType);
2380 }
2381 // </editor-fold>
2383 // <editor-fold defaultstate="collapsed" desc="rank">
2384 /**
2385 * The rank of a class is the length of the longest path between
2386 * the class and java.lang.Object in the class inheritance
2387 * graph. Undefined for all but reference types.
2388 */
2389 public int rank(Type t) {
2390 switch(t.tag) {
2391 case CLASS: {
2392 ClassType cls = (ClassType)t;
2393 if (cls.rank_field < 0) {
2394 Name fullname = cls.tsym.getQualifiedName();
2395 if (fullname == names.java_lang_Object)
2396 cls.rank_field = 0;
2397 else {
2398 int r = rank(supertype(cls));
2399 for (List<Type> l = interfaces(cls);
2400 l.nonEmpty();
2401 l = l.tail) {
2402 if (rank(l.head) > r)
2403 r = rank(l.head);
2404 }
2405 cls.rank_field = r + 1;
2406 }
2407 }
2408 return cls.rank_field;
2409 }
2410 case TYPEVAR: {
2411 TypeVar tvar = (TypeVar)t;
2412 if (tvar.rank_field < 0) {
2413 int r = rank(supertype(tvar));
2414 for (List<Type> l = interfaces(tvar);
2415 l.nonEmpty();
2416 l = l.tail) {
2417 if (rank(l.head) > r) r = rank(l.head);
2418 }
2419 tvar.rank_field = r + 1;
2420 }
2421 return tvar.rank_field;
2422 }
2423 case ERROR:
2424 return 0;
2425 default:
2426 throw new AssertionError();
2427 }
2428 }
2429 // </editor-fold>
2431 /**
2432 * Helper method for generating a string representation of a given type
2433 * accordingly to a given locale
2434 */
2435 public String toString(Type t, Locale locale) {
2436 return Printer.createStandardPrinter(messages).visit(t, locale);
2437 }
2439 /**
2440 * Helper method for generating a string representation of a given type
2441 * accordingly to a given locale
2442 */
2443 public String toString(Symbol t, Locale locale) {
2444 return Printer.createStandardPrinter(messages).visit(t, locale);
2445 }
2447 // <editor-fold defaultstate="collapsed" desc="toString">
2448 /**
2449 * This toString is slightly more descriptive than the one on Type.
2450 *
2451 * @deprecated Types.toString(Type t, Locale l) provides better support
2452 * for localization
2453 */
2454 @Deprecated
2455 public String toString(Type t) {
2456 if (t.tag == FORALL) {
2457 ForAll forAll = (ForAll)t;
2458 return typaramsString(forAll.tvars) + forAll.qtype;
2459 }
2460 return "" + t;
2461 }
2462 // where
2463 private String typaramsString(List<Type> tvars) {
2464 StringBuffer s = new StringBuffer();
2465 s.append('<');
2466 boolean first = true;
2467 for (Type t : tvars) {
2468 if (!first) s.append(", ");
2469 first = false;
2470 appendTyparamString(((TypeVar)t), s);
2471 }
2472 s.append('>');
2473 return s.toString();
2474 }
2475 private void appendTyparamString(TypeVar t, StringBuffer buf) {
2476 buf.append(t);
2477 if (t.bound == null ||
2478 t.bound.tsym.getQualifiedName() == names.java_lang_Object)
2479 return;
2480 buf.append(" extends "); // Java syntax; no need for i18n
2481 Type bound = t.bound;
2482 if (!bound.isCompound()) {
2483 buf.append(bound);
2484 } else if ((erasure(t).tsym.flags() & INTERFACE) == 0) {
2485 buf.append(supertype(t));
2486 for (Type intf : interfaces(t)) {
2487 buf.append('&');
2488 buf.append(intf);
2489 }
2490 } else {
2491 // No superclass was given in bounds.
2492 // In this case, supertype is Object, erasure is first interface.
2493 boolean first = true;
2494 for (Type intf : interfaces(t)) {
2495 if (!first) buf.append('&');
2496 first = false;
2497 buf.append(intf);
2498 }
2499 }
2500 }
2501 // </editor-fold>
2503 // <editor-fold defaultstate="collapsed" desc="Determining least upper bounds of types">
2504 /**
2505 * A cache for closures.
2506 *
2507 * <p>A closure is a list of all the supertypes and interfaces of
2508 * a class or interface type, ordered by ClassSymbol.precedes
2509 * (that is, subclasses come first, arbitrary but fixed
2510 * otherwise).
2511 */
2512 private Map<Type,List<Type>> closureCache = new HashMap<Type,List<Type>>();
2514 /**
2515 * Returns the closure of a class or interface type.
2516 */
2517 public List<Type> closure(Type t) {
2518 List<Type> cl = closureCache.get(t);
2519 if (cl == null) {
2520 Type st = supertype(t);
2521 if (!t.isCompound()) {
2522 if (st.tag == CLASS) {
2523 cl = insert(closure(st), t);
2524 } else if (st.tag == TYPEVAR) {
2525 cl = closure(st).prepend(t);
2526 } else {
2527 cl = List.of(t);
2528 }
2529 } else {
2530 cl = closure(supertype(t));
2531 }
2532 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail)
2533 cl = union(cl, closure(l.head));
2534 closureCache.put(t, cl);
2535 }
2536 return cl;
2537 }
2539 /**
2540 * Insert a type in a closure
2541 */
2542 public List<Type> insert(List<Type> cl, Type t) {
2543 if (cl.isEmpty() || t.tsym.precedes(cl.head.tsym, this)) {
2544 return cl.prepend(t);
2545 } else if (cl.head.tsym.precedes(t.tsym, this)) {
2546 return insert(cl.tail, t).prepend(cl.head);
2547 } else {
2548 return cl;
2549 }
2550 }
2552 /**
2553 * Form the union of two closures
2554 */
2555 public List<Type> union(List<Type> cl1, List<Type> cl2) {
2556 if (cl1.isEmpty()) {
2557 return cl2;
2558 } else if (cl2.isEmpty()) {
2559 return cl1;
2560 } else if (cl1.head.tsym.precedes(cl2.head.tsym, this)) {
2561 return union(cl1.tail, cl2).prepend(cl1.head);
2562 } else if (cl2.head.tsym.precedes(cl1.head.tsym, this)) {
2563 return union(cl1, cl2.tail).prepend(cl2.head);
2564 } else {
2565 return union(cl1.tail, cl2.tail).prepend(cl1.head);
2566 }
2567 }
2569 /**
2570 * Intersect two closures
2571 */
2572 public List<Type> intersect(List<Type> cl1, List<Type> cl2) {
2573 if (cl1 == cl2)
2574 return cl1;
2575 if (cl1.isEmpty() || cl2.isEmpty())
2576 return List.nil();
2577 if (cl1.head.tsym.precedes(cl2.head.tsym, this))
2578 return intersect(cl1.tail, cl2);
2579 if (cl2.head.tsym.precedes(cl1.head.tsym, this))
2580 return intersect(cl1, cl2.tail);
2581 if (isSameType(cl1.head, cl2.head))
2582 return intersect(cl1.tail, cl2.tail).prepend(cl1.head);
2583 if (cl1.head.tsym == cl2.head.tsym &&
2584 cl1.head.tag == CLASS && cl2.head.tag == CLASS) {
2585 if (cl1.head.isParameterized() && cl2.head.isParameterized()) {
2586 Type merge = merge(cl1.head,cl2.head);
2587 return intersect(cl1.tail, cl2.tail).prepend(merge);
2588 }
2589 if (cl1.head.isRaw() || cl2.head.isRaw())
2590 return intersect(cl1.tail, cl2.tail).prepend(erasure(cl1.head));
2591 }
2592 return intersect(cl1.tail, cl2.tail);
2593 }
2594 // where
2595 class TypePair {
2596 final Type t1;
2597 final Type t2;
2598 TypePair(Type t1, Type t2) {
2599 this.t1 = t1;
2600 this.t2 = t2;
2601 }
2602 @Override
2603 public int hashCode() {
2604 return 127 * Types.hashCode(t1) + Types.hashCode(t2);
2605 }
2606 @Override
2607 public boolean equals(Object obj) {
2608 if (!(obj instanceof TypePair))
2609 return false;
2610 TypePair typePair = (TypePair)obj;
2611 return isSameType(t1, typePair.t1)
2612 && isSameType(t2, typePair.t2);
2613 }
2614 }
2615 Set<TypePair> mergeCache = new HashSet<TypePair>();
2616 private Type merge(Type c1, Type c2) {
2617 ClassType class1 = (ClassType) c1;
2618 List<Type> act1 = class1.getTypeArguments();
2619 ClassType class2 = (ClassType) c2;
2620 List<Type> act2 = class2.getTypeArguments();
2621 ListBuffer<Type> merged = new ListBuffer<Type>();
2622 List<Type> typarams = class1.tsym.type.getTypeArguments();
2624 while (act1.nonEmpty() && act2.nonEmpty() && typarams.nonEmpty()) {
2625 if (containsType(act1.head, act2.head)) {
2626 merged.append(act1.head);
2627 } else if (containsType(act2.head, act1.head)) {
2628 merged.append(act2.head);
2629 } else {
2630 TypePair pair = new TypePair(c1, c2);
2631 Type m;
2632 if (mergeCache.add(pair)) {
2633 m = new WildcardType(lub(upperBound(act1.head),
2634 upperBound(act2.head)),
2635 BoundKind.EXTENDS,
2636 syms.boundClass);
2637 mergeCache.remove(pair);
2638 } else {
2639 m = new WildcardType(syms.objectType,
2640 BoundKind.UNBOUND,
2641 syms.boundClass);
2642 }
2643 merged.append(m.withTypeVar(typarams.head));
2644 }
2645 act1 = act1.tail;
2646 act2 = act2.tail;
2647 typarams = typarams.tail;
2648 }
2649 assert(act1.isEmpty() && act2.isEmpty() && typarams.isEmpty());
2650 return new ClassType(class1.getEnclosingType(), merged.toList(), class1.tsym);
2651 }
2653 /**
2654 * Return the minimum type of a closure, a compound type if no
2655 * unique minimum exists.
2656 */
2657 private Type compoundMin(List<Type> cl) {
2658 if (cl.isEmpty()) return syms.objectType;
2659 List<Type> compound = closureMin(cl);
2660 if (compound.isEmpty())
2661 return null;
2662 else if (compound.tail.isEmpty())
2663 return compound.head;
2664 else
2665 return makeCompoundType(compound);
2666 }
2668 /**
2669 * Return the minimum types of a closure, suitable for computing
2670 * compoundMin or glb.
2671 */
2672 private List<Type> closureMin(List<Type> cl) {
2673 ListBuffer<Type> classes = lb();
2674 ListBuffer<Type> interfaces = lb();
2675 while (!cl.isEmpty()) {
2676 Type current = cl.head;
2677 if (current.isInterface())
2678 interfaces.append(current);
2679 else
2680 classes.append(current);
2681 ListBuffer<Type> candidates = lb();
2682 for (Type t : cl.tail) {
2683 if (!isSubtypeNoCapture(current, t))
2684 candidates.append(t);
2685 }
2686 cl = candidates.toList();
2687 }
2688 return classes.appendList(interfaces).toList();
2689 }
2691 /**
2692 * Return the least upper bound of pair of types. if the lub does
2693 * not exist return null.
2694 */
2695 public Type lub(Type t1, Type t2) {
2696 return lub(List.of(t1, t2));
2697 }
2699 /**
2700 * Return the least upper bound (lub) of set of types. If the lub
2701 * does not exist return the type of null (bottom).
2702 */
2703 public Type lub(List<Type> ts) {
2704 final int ARRAY_BOUND = 1;
2705 final int CLASS_BOUND = 2;
2706 int boundkind = 0;
2707 for (Type t : ts) {
2708 switch (t.tag) {
2709 case CLASS:
2710 boundkind |= CLASS_BOUND;
2711 break;
2712 case ARRAY:
2713 boundkind |= ARRAY_BOUND;
2714 break;
2715 case TYPEVAR:
2716 do {
2717 t = t.getUpperBound();
2718 } while (t.tag == TYPEVAR);
2719 if (t.tag == ARRAY) {
2720 boundkind |= ARRAY_BOUND;
2721 } else {
2722 boundkind |= CLASS_BOUND;
2723 }
2724 break;
2725 default:
2726 if (t.isPrimitive())
2727 return syms.errType;
2728 }
2729 }
2730 switch (boundkind) {
2731 case 0:
2732 return syms.botType;
2734 case ARRAY_BOUND:
2735 // calculate lub(A[], B[])
2736 List<Type> elements = Type.map(ts, elemTypeFun);
2737 for (Type t : elements) {
2738 if (t.isPrimitive()) {
2739 // if a primitive type is found, then return
2740 // arraySuperType unless all the types are the
2741 // same
2742 Type first = ts.head;
2743 for (Type s : ts.tail) {
2744 if (!isSameType(first, s)) {
2745 // lub(int[], B[]) is Cloneable & Serializable
2746 return arraySuperType();
2747 }
2748 }
2749 // all the array types are the same, return one
2750 // lub(int[], int[]) is int[]
2751 return first;
2752 }
2753 }
2754 // lub(A[], B[]) is lub(A, B)[]
2755 return new ArrayType(lub(elements), syms.arrayClass);
2757 case CLASS_BOUND:
2758 // calculate lub(A, B)
2759 while (ts.head.tag != CLASS && ts.head.tag != TYPEVAR)
2760 ts = ts.tail;
2761 assert !ts.isEmpty();
2762 List<Type> cl = closure(ts.head);
2763 for (Type t : ts.tail) {
2764 if (t.tag == CLASS || t.tag == TYPEVAR)
2765 cl = intersect(cl, closure(t));
2766 }
2767 return compoundMin(cl);
2769 default:
2770 // calculate lub(A, B[])
2771 List<Type> classes = List.of(arraySuperType());
2772 for (Type t : ts) {
2773 if (t.tag != ARRAY) // Filter out any arrays
2774 classes = classes.prepend(t);
2775 }
2776 // lub(A, B[]) is lub(A, arraySuperType)
2777 return lub(classes);
2778 }
2779 }
2780 // where
2781 private Type arraySuperType = null;
2782 private Type arraySuperType() {
2783 // initialized lazily to avoid problems during compiler startup
2784 if (arraySuperType == null) {
2785 synchronized (this) {
2786 if (arraySuperType == null) {
2787 // JLS 10.8: all arrays implement Cloneable and Serializable.
2788 arraySuperType = makeCompoundType(List.of(syms.serializableType,
2789 syms.cloneableType),
2790 syms.objectType);
2791 }
2792 }
2793 }
2794 return arraySuperType;
2795 }
2796 // </editor-fold>
2798 // <editor-fold defaultstate="collapsed" desc="Greatest lower bound">
2799 public Type glb(List<Type> ts) {
2800 Type t1 = ts.head;
2801 for (Type t2 : ts.tail) {
2802 if (t1.isErroneous())
2803 return t1;
2804 t1 = glb(t1, t2);
2805 }
2806 return t1;
2807 }
2808 //where
2809 public Type glb(Type t, Type s) {
2810 if (s == null)
2811 return t;
2812 else if (t.isPrimitive() || s.isPrimitive())
2813 return syms.errType;
2814 else if (isSubtypeNoCapture(t, s))
2815 return t;
2816 else if (isSubtypeNoCapture(s, t))
2817 return s;
2819 List<Type> closure = union(closure(t), closure(s));
2820 List<Type> bounds = closureMin(closure);
2822 if (bounds.isEmpty()) { // length == 0
2823 return syms.objectType;
2824 } else if (bounds.tail.isEmpty()) { // length == 1
2825 return bounds.head;
2826 } else { // length > 1
2827 int classCount = 0;
2828 for (Type bound : bounds)
2829 if (!bound.isInterface())
2830 classCount++;
2831 if (classCount > 1)
2832 return createErrorType(t);
2833 }
2834 return makeCompoundType(bounds);
2835 }
2836 // </editor-fold>
2838 // <editor-fold defaultstate="collapsed" desc="hashCode">
2839 /**
2840 * Compute a hash code on a type.
2841 */
2842 public static int hashCode(Type t) {
2843 return hashCode.visit(t);
2844 }
2845 // where
2846 private static final UnaryVisitor<Integer> hashCode = new UnaryVisitor<Integer>() {
2848 public Integer visitType(Type t, Void ignored) {
2849 return t.tag;
2850 }
2852 @Override
2853 public Integer visitClassType(ClassType t, Void ignored) {
2854 int result = visit(t.getEnclosingType());
2855 result *= 127;
2856 result += t.tsym.flatName().hashCode();
2857 for (Type s : t.getTypeArguments()) {
2858 result *= 127;
2859 result += visit(s);
2860 }
2861 return result;
2862 }
2864 @Override
2865 public Integer visitWildcardType(WildcardType t, Void ignored) {
2866 int result = t.kind.hashCode();
2867 if (t.type != null) {
2868 result *= 127;
2869 result += visit(t.type);
2870 }
2871 return result;
2872 }
2874 @Override
2875 public Integer visitArrayType(ArrayType t, Void ignored) {
2876 return visit(t.elemtype) + 12;
2877 }
2879 @Override
2880 public Integer visitTypeVar(TypeVar t, Void ignored) {
2881 return System.identityHashCode(t.tsym);
2882 }
2884 @Override
2885 public Integer visitUndetVar(UndetVar t, Void ignored) {
2886 return System.identityHashCode(t);
2887 }
2889 @Override
2890 public Integer visitErrorType(ErrorType t, Void ignored) {
2891 return 0;
2892 }
2893 };
2894 // </editor-fold>
2896 // <editor-fold defaultstate="collapsed" desc="Return-Type-Substitutable">
2897 /**
2898 * Does t have a result that is a subtype of the result type of s,
2899 * suitable for covariant returns? It is assumed that both types
2900 * are (possibly polymorphic) method types. Monomorphic method
2901 * types are handled in the obvious way. Polymorphic method types
2902 * require renaming all type variables of one to corresponding
2903 * type variables in the other, where correspondence is by
2904 * position in the type parameter list. */
2905 public boolean resultSubtype(Type t, Type s, Warner warner) {
2906 List<Type> tvars = t.getTypeArguments();
2907 List<Type> svars = s.getTypeArguments();
2908 Type tres = t.getReturnType();
2909 Type sres = subst(s.getReturnType(), svars, tvars);
2910 return covariantReturnType(tres, sres, warner);
2911 }
2913 /**
2914 * Return-Type-Substitutable.
2915 * @see <a href="http://java.sun.com/docs/books/jls/">The Java
2916 * Language Specification, Third Ed. (8.4.5)</a>
2917 */
2918 public boolean returnTypeSubstitutable(Type r1, Type r2) {
2919 if (hasSameArgs(r1, r2))
2920 return resultSubtype(r1, r2, Warner.noWarnings);
2921 else
2922 return covariantReturnType(r1.getReturnType(),
2923 erasure(r2.getReturnType()),
2924 Warner.noWarnings);
2925 }
2927 public boolean returnTypeSubstitutable(Type r1,
2928 Type r2, Type r2res,
2929 Warner warner) {
2930 if (isSameType(r1.getReturnType(), r2res))
2931 return true;
2932 if (r1.getReturnType().isPrimitive() || r2res.isPrimitive())
2933 return false;
2935 if (hasSameArgs(r1, r2))
2936 return covariantReturnType(r1.getReturnType(), r2res, warner);
2937 if (!source.allowCovariantReturns())
2938 return false;
2939 if (isSubtypeUnchecked(r1.getReturnType(), r2res, warner))
2940 return true;
2941 if (!isSubtype(r1.getReturnType(), erasure(r2res)))
2942 return false;
2943 warner.warn(LintCategory.UNCHECKED);
2944 return true;
2945 }
2947 /**
2948 * Is t an appropriate return type in an overrider for a
2949 * method that returns s?
2950 */
2951 public boolean covariantReturnType(Type t, Type s, Warner warner) {
2952 return
2953 isSameType(t, s) ||
2954 source.allowCovariantReturns() &&
2955 !t.isPrimitive() &&
2956 !s.isPrimitive() &&
2957 isAssignable(t, s, warner);
2958 }
2959 // </editor-fold>
2961 // <editor-fold defaultstate="collapsed" desc="Box/unbox support">
2962 /**
2963 * Return the class that boxes the given primitive.
2964 */
2965 public ClassSymbol boxedClass(Type t) {
2966 return reader.enterClass(syms.boxedName[t.tag]);
2967 }
2969 /**
2970 * Return the boxed type if 't' is primitive, otherwise return 't' itself.
2971 */
2972 public Type boxedTypeOrType(Type t) {
2973 return t.isPrimitive() ?
2974 boxedClass(t).type :
2975 t;
2976 }
2978 /**
2979 * Return the primitive type corresponding to a boxed type.
2980 */
2981 public Type unboxedType(Type t) {
2982 if (allowBoxing) {
2983 for (int i=0; i<syms.boxedName.length; i++) {
2984 Name box = syms.boxedName[i];
2985 if (box != null &&
2986 asSuper(t, reader.enterClass(box)) != null)
2987 return syms.typeOfTag[i];
2988 }
2989 }
2990 return Type.noType;
2991 }
2992 // </editor-fold>
2994 // <editor-fold defaultstate="collapsed" desc="Capture conversion">
2995 /*
2996 * JLS 3rd Ed. 5.1.10 Capture Conversion:
2997 *
2998 * Let G name a generic type declaration with n formal type
2999 * parameters A1 ... An with corresponding bounds U1 ... Un. There
3000 * exists a capture conversion from G<T1 ... Tn> to G<S1 ... Sn>,
3001 * where, for 1 <= i <= n:
3002 *
3003 * + If Ti is a wildcard type argument (4.5.1) of the form ? then
3004 * Si is a fresh type variable whose upper bound is
3005 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is the null
3006 * type.
3007 *
3008 * + If Ti is a wildcard type argument of the form ? extends Bi,
3009 * then Si is a fresh type variable whose upper bound is
3010 * glb(Bi, Ui[A1 := S1, ..., An := Sn]) and whose lower bound is
3011 * the null type, where glb(V1,... ,Vm) is V1 & ... & Vm. It is
3012 * a compile-time error if for any two classes (not interfaces)
3013 * Vi and Vj,Vi is not a subclass of Vj or vice versa.
3014 *
3015 * + If Ti is a wildcard type argument of the form ? super Bi,
3016 * then Si is a fresh type variable whose upper bound is
3017 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is Bi.
3018 *
3019 * + Otherwise, Si = Ti.
3020 *
3021 * Capture conversion on any type other than a parameterized type
3022 * (4.5) acts as an identity conversion (5.1.1). Capture
3023 * conversions never require a special action at run time and
3024 * therefore never throw an exception at run time.
3025 *
3026 * Capture conversion is not applied recursively.
3027 */
3028 /**
3029 * Capture conversion as specified by JLS 3rd Ed.
3030 */
3032 public List<Type> capture(List<Type> ts) {
3033 List<Type> buf = List.nil();
3034 for (Type t : ts) {
3035 buf = buf.prepend(capture(t));
3036 }
3037 return buf.reverse();
3038 }
3039 public Type capture(Type t) {
3040 if (t.tag != CLASS)
3041 return t;
3042 if (t.getEnclosingType() != Type.noType) {
3043 Type capturedEncl = capture(t.getEnclosingType());
3044 if (capturedEncl != t.getEnclosingType()) {
3045 Type type1 = memberType(capturedEncl, t.tsym);
3046 t = subst(type1, t.tsym.type.getTypeArguments(), t.getTypeArguments());
3047 }
3048 }
3049 ClassType cls = (ClassType)t;
3050 if (cls.isRaw() || !cls.isParameterized())
3051 return cls;
3053 ClassType G = (ClassType)cls.asElement().asType();
3054 List<Type> A = G.getTypeArguments();
3055 List<Type> T = cls.getTypeArguments();
3056 List<Type> S = freshTypeVariables(T);
3058 List<Type> currentA = A;
3059 List<Type> currentT = T;
3060 List<Type> currentS = S;
3061 boolean captured = false;
3062 while (!currentA.isEmpty() &&
3063 !currentT.isEmpty() &&
3064 !currentS.isEmpty()) {
3065 if (currentS.head != currentT.head) {
3066 captured = true;
3067 WildcardType Ti = (WildcardType)currentT.head;
3068 Type Ui = currentA.head.getUpperBound();
3069 CapturedType Si = (CapturedType)currentS.head;
3070 if (Ui == null)
3071 Ui = syms.objectType;
3072 switch (Ti.kind) {
3073 case UNBOUND:
3074 Si.bound = subst(Ui, A, S);
3075 Si.lower = syms.botType;
3076 break;
3077 case EXTENDS:
3078 Si.bound = glb(Ti.getExtendsBound(), subst(Ui, A, S));
3079 Si.lower = syms.botType;
3080 break;
3081 case SUPER:
3082 Si.bound = subst(Ui, A, S);
3083 Si.lower = Ti.getSuperBound();
3084 break;
3085 }
3086 if (Si.bound == Si.lower)
3087 currentS.head = Si.bound;
3088 }
3089 currentA = currentA.tail;
3090 currentT = currentT.tail;
3091 currentS = currentS.tail;
3092 }
3093 if (!currentA.isEmpty() || !currentT.isEmpty() || !currentS.isEmpty())
3094 return erasure(t); // some "rare" type involved
3096 if (captured)
3097 return new ClassType(cls.getEnclosingType(), S, cls.tsym);
3098 else
3099 return t;
3100 }
3101 // where
3102 public List<Type> freshTypeVariables(List<Type> types) {
3103 ListBuffer<Type> result = lb();
3104 for (Type t : types) {
3105 if (t.tag == WILDCARD) {
3106 Type bound = ((WildcardType)t).getExtendsBound();
3107 if (bound == null)
3108 bound = syms.objectType;
3109 result.append(new CapturedType(capturedName,
3110 syms.noSymbol,
3111 bound,
3112 syms.botType,
3113 (WildcardType)t));
3114 } else {
3115 result.append(t);
3116 }
3117 }
3118 return result.toList();
3119 }
3120 // </editor-fold>
3122 // <editor-fold defaultstate="collapsed" desc="Internal utility methods">
3123 private List<Type> upperBounds(List<Type> ss) {
3124 if (ss.isEmpty()) return ss;
3125 Type head = upperBound(ss.head);
3126 List<Type> tail = upperBounds(ss.tail);
3127 if (head != ss.head || tail != ss.tail)
3128 return tail.prepend(head);
3129 else
3130 return ss;
3131 }
3133 private boolean sideCast(Type from, Type to, Warner warn) {
3134 // We are casting from type $from$ to type $to$, which are
3135 // non-final unrelated types. This method
3136 // tries to reject a cast by transferring type parameters
3137 // from $to$ to $from$ by common superinterfaces.
3138 boolean reverse = false;
3139 Type target = to;
3140 if ((to.tsym.flags() & INTERFACE) == 0) {
3141 assert (from.tsym.flags() & INTERFACE) != 0;
3142 reverse = true;
3143 to = from;
3144 from = target;
3145 }
3146 List<Type> commonSupers = superClosure(to, erasure(from));
3147 boolean giveWarning = commonSupers.isEmpty();
3148 // The arguments to the supers could be unified here to
3149 // get a more accurate analysis
3150 while (commonSupers.nonEmpty()) {
3151 Type t1 = asSuper(from, commonSupers.head.tsym);
3152 Type t2 = commonSupers.head; // same as asSuper(to, commonSupers.head.tsym);
3153 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
3154 return false;
3155 giveWarning = giveWarning || (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2));
3156 commonSupers = commonSupers.tail;
3157 }
3158 if (giveWarning && !isReifiable(reverse ? from : to))
3159 warn.warn(LintCategory.UNCHECKED);
3160 if (!source.allowCovariantReturns())
3161 // reject if there is a common method signature with
3162 // incompatible return types.
3163 chk.checkCompatibleAbstracts(warn.pos(), from, to);
3164 return true;
3165 }
3167 private boolean sideCastFinal(Type from, Type to, Warner warn) {
3168 // We are casting from type $from$ to type $to$, which are
3169 // unrelated types one of which is final and the other of
3170 // which is an interface. This method
3171 // tries to reject a cast by transferring type parameters
3172 // from the final class to the interface.
3173 boolean reverse = false;
3174 Type target = to;
3175 if ((to.tsym.flags() & INTERFACE) == 0) {
3176 assert (from.tsym.flags() & INTERFACE) != 0;
3177 reverse = true;
3178 to = from;
3179 from = target;
3180 }
3181 assert (from.tsym.flags() & FINAL) != 0;
3182 Type t1 = asSuper(from, to.tsym);
3183 if (t1 == null) return false;
3184 Type t2 = to;
3185 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
3186 return false;
3187 if (!source.allowCovariantReturns())
3188 // reject if there is a common method signature with
3189 // incompatible return types.
3190 chk.checkCompatibleAbstracts(warn.pos(), from, to);
3191 if (!isReifiable(target) &&
3192 (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2)))
3193 warn.warn(LintCategory.UNCHECKED);
3194 return true;
3195 }
3197 private boolean giveWarning(Type from, Type to) {
3198 Type subFrom = asSub(from, to.tsym);
3199 return to.isParameterized() &&
3200 (!(isUnbounded(to) ||
3201 isSubtype(from, to) ||
3202 ((subFrom != null) && containsType(to.allparams(), subFrom.allparams()))));
3203 }
3205 private List<Type> superClosure(Type t, Type s) {
3206 List<Type> cl = List.nil();
3207 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
3208 if (isSubtype(s, erasure(l.head))) {
3209 cl = insert(cl, l.head);
3210 } else {
3211 cl = union(cl, superClosure(l.head, s));
3212 }
3213 }
3214 return cl;
3215 }
3217 private boolean containsTypeEquivalent(Type t, Type s) {
3218 return
3219 isSameType(t, s) || // shortcut
3220 containsType(t, s) && containsType(s, t);
3221 }
3223 // <editor-fold defaultstate="collapsed" desc="adapt">
3224 /**
3225 * Adapt a type by computing a substitution which maps a source
3226 * type to a target type.
3227 *
3228 * @param source the source type
3229 * @param target the target type
3230 * @param from the type variables of the computed substitution
3231 * @param to the types of the computed substitution.
3232 */
3233 public void adapt(Type source,
3234 Type target,
3235 ListBuffer<Type> from,
3236 ListBuffer<Type> to) throws AdaptFailure {
3237 new Adapter(from, to).adapt(source, target);
3238 }
3240 class Adapter extends SimpleVisitor<Void, Type> {
3242 ListBuffer<Type> from;
3243 ListBuffer<Type> to;
3244 Map<Symbol,Type> mapping;
3246 Adapter(ListBuffer<Type> from, ListBuffer<Type> to) {
3247 this.from = from;
3248 this.to = to;
3249 mapping = new HashMap<Symbol,Type>();
3250 }
3252 public void adapt(Type source, Type target) throws AdaptFailure {
3253 visit(source, target);
3254 List<Type> fromList = from.toList();
3255 List<Type> toList = to.toList();
3256 while (!fromList.isEmpty()) {
3257 Type val = mapping.get(fromList.head.tsym);
3258 if (toList.head != val)
3259 toList.head = val;
3260 fromList = fromList.tail;
3261 toList = toList.tail;
3262 }
3263 }
3265 @Override
3266 public Void visitClassType(ClassType source, Type target) throws AdaptFailure {
3267 if (target.tag == CLASS)
3268 adaptRecursive(source.allparams(), target.allparams());
3269 return null;
3270 }
3272 @Override
3273 public Void visitArrayType(ArrayType source, Type target) throws AdaptFailure {
3274 if (target.tag == ARRAY)
3275 adaptRecursive(elemtype(source), elemtype(target));
3276 return null;
3277 }
3279 @Override
3280 public Void visitWildcardType(WildcardType source, Type target) throws AdaptFailure {
3281 if (source.isExtendsBound())
3282 adaptRecursive(upperBound(source), upperBound(target));
3283 else if (source.isSuperBound())
3284 adaptRecursive(lowerBound(source), lowerBound(target));
3285 return null;
3286 }
3288 @Override
3289 public Void visitTypeVar(TypeVar source, Type target) throws AdaptFailure {
3290 // Check to see if there is
3291 // already a mapping for $source$, in which case
3292 // the old mapping will be merged with the new
3293 Type val = mapping.get(source.tsym);
3294 if (val != null) {
3295 if (val.isSuperBound() && target.isSuperBound()) {
3296 val = isSubtype(lowerBound(val), lowerBound(target))
3297 ? target : val;
3298 } else if (val.isExtendsBound() && target.isExtendsBound()) {
3299 val = isSubtype(upperBound(val), upperBound(target))
3300 ? val : target;
3301 } else if (!isSameType(val, target)) {
3302 throw new AdaptFailure();
3303 }
3304 } else {
3305 val = target;
3306 from.append(source);
3307 to.append(target);
3308 }
3309 mapping.put(source.tsym, val);
3310 return null;
3311 }
3313 @Override
3314 public Void visitType(Type source, Type target) {
3315 return null;
3316 }
3318 private Set<TypePair> cache = new HashSet<TypePair>();
3320 private void adaptRecursive(Type source, Type target) {
3321 TypePair pair = new TypePair(source, target);
3322 if (cache.add(pair)) {
3323 try {
3324 visit(source, target);
3325 } finally {
3326 cache.remove(pair);
3327 }
3328 }
3329 }
3331 private void adaptRecursive(List<Type> source, List<Type> target) {
3332 if (source.length() == target.length()) {
3333 while (source.nonEmpty()) {
3334 adaptRecursive(source.head, target.head);
3335 source = source.tail;
3336 target = target.tail;
3337 }
3338 }
3339 }
3340 }
3342 public static class AdaptFailure extends RuntimeException {
3343 static final long serialVersionUID = -7490231548272701566L;
3344 }
3346 private void adaptSelf(Type t,
3347 ListBuffer<Type> from,
3348 ListBuffer<Type> to) {
3349 try {
3350 //if (t.tsym.type != t)
3351 adapt(t.tsym.type, t, from, to);
3352 } catch (AdaptFailure ex) {
3353 // Adapt should never fail calculating a mapping from
3354 // t.tsym.type to t as there can be no merge problem.
3355 throw new AssertionError(ex);
3356 }
3357 }
3358 // </editor-fold>
3360 /**
3361 * Rewrite all type variables (universal quantifiers) in the given
3362 * type to wildcards (existential quantifiers). This is used to
3363 * determine if a cast is allowed. For example, if high is true
3364 * and {@code T <: Number}, then {@code List<T>} is rewritten to
3365 * {@code List<? extends Number>}. Since {@code List<Integer> <:
3366 * List<? extends Number>} a {@code List<T>} can be cast to {@code
3367 * List<Integer>} with a warning.
3368 * @param t a type
3369 * @param high if true return an upper bound; otherwise a lower
3370 * bound
3371 * @param rewriteTypeVars only rewrite captured wildcards if false;
3372 * otherwise rewrite all type variables
3373 * @return the type rewritten with wildcards (existential
3374 * quantifiers) only
3375 */
3376 private Type rewriteQuantifiers(Type t, boolean high, boolean rewriteTypeVars) {
3377 return new Rewriter(high, rewriteTypeVars).visit(t);
3378 }
3380 class Rewriter extends UnaryVisitor<Type> {
3382 boolean high;
3383 boolean rewriteTypeVars;
3385 Rewriter(boolean high, boolean rewriteTypeVars) {
3386 this.high = high;
3387 this.rewriteTypeVars = rewriteTypeVars;
3388 }
3390 @Override
3391 public Type visitClassType(ClassType t, Void s) {
3392 ListBuffer<Type> rewritten = new ListBuffer<Type>();
3393 boolean changed = false;
3394 for (Type arg : t.allparams()) {
3395 Type bound = visit(arg);
3396 if (arg != bound) {
3397 changed = true;
3398 }
3399 rewritten.append(bound);
3400 }
3401 if (changed)
3402 return subst(t.tsym.type,
3403 t.tsym.type.allparams(),
3404 rewritten.toList());
3405 else
3406 return t;
3407 }
3409 public Type visitType(Type t, Void s) {
3410 return high ? upperBound(t) : lowerBound(t);
3411 }
3413 @Override
3414 public Type visitCapturedType(CapturedType t, Void s) {
3415 Type bound = visitWildcardType(t.wildcard, null);
3416 return (bound.contains(t)) ?
3417 erasure(bound) :
3418 bound;
3419 }
3421 @Override
3422 public Type visitTypeVar(TypeVar t, Void s) {
3423 if (rewriteTypeVars) {
3424 Type bound = high ?
3425 (t.bound.contains(t) ?
3426 erasure(t.bound) :
3427 visit(t.bound)) :
3428 syms.botType;
3429 return rewriteAsWildcardType(bound, t);
3430 }
3431 else
3432 return t;
3433 }
3435 @Override
3436 public Type visitWildcardType(WildcardType t, Void s) {
3437 Type bound = high ? t.getExtendsBound() :
3438 t.getSuperBound();
3439 if (bound == null)
3440 bound = high ? syms.objectType : syms.botType;
3441 return rewriteAsWildcardType(visit(bound), t.bound);
3442 }
3444 private Type rewriteAsWildcardType(Type bound, TypeVar formal) {
3445 return high ?
3446 makeExtendsWildcard(B(bound), formal) :
3447 makeSuperWildcard(B(bound), formal);
3448 }
3450 Type B(Type t) {
3451 while (t.tag == WILDCARD) {
3452 WildcardType w = (WildcardType)t;
3453 t = high ?
3454 w.getExtendsBound() :
3455 w.getSuperBound();
3456 if (t == null) {
3457 t = high ? syms.objectType : syms.botType;
3458 }
3459 }
3460 return t;
3461 }
3462 }
3465 /**
3466 * Create a wildcard with the given upper (extends) bound; create
3467 * an unbounded wildcard if bound is Object.
3468 *
3469 * @param bound the upper bound
3470 * @param formal the formal type parameter that will be
3471 * substituted by the wildcard
3472 */
3473 private WildcardType makeExtendsWildcard(Type bound, TypeVar formal) {
3474 if (bound == syms.objectType) {
3475 return new WildcardType(syms.objectType,
3476 BoundKind.UNBOUND,
3477 syms.boundClass,
3478 formal);
3479 } else {
3480 return new WildcardType(bound,
3481 BoundKind.EXTENDS,
3482 syms.boundClass,
3483 formal);
3484 }
3485 }
3487 /**
3488 * Create a wildcard with the given lower (super) bound; create an
3489 * unbounded wildcard if bound is bottom (type of {@code null}).
3490 *
3491 * @param bound the lower bound
3492 * @param formal the formal type parameter that will be
3493 * substituted by the wildcard
3494 */
3495 private WildcardType makeSuperWildcard(Type bound, TypeVar formal) {
3496 if (bound.tag == BOT) {
3497 return new WildcardType(syms.objectType,
3498 BoundKind.UNBOUND,
3499 syms.boundClass,
3500 formal);
3501 } else {
3502 return new WildcardType(bound,
3503 BoundKind.SUPER,
3504 syms.boundClass,
3505 formal);
3506 }
3507 }
3509 /**
3510 * A wrapper for a type that allows use in sets.
3511 */
3512 class SingletonType {
3513 final Type t;
3514 SingletonType(Type t) {
3515 this.t = t;
3516 }
3517 public int hashCode() {
3518 return Types.hashCode(t);
3519 }
3520 public boolean equals(Object obj) {
3521 return (obj instanceof SingletonType) &&
3522 isSameType(t, ((SingletonType)obj).t);
3523 }
3524 public String toString() {
3525 return t.toString();
3526 }
3527 }
3528 // </editor-fold>
3530 // <editor-fold defaultstate="collapsed" desc="Visitors">
3531 /**
3532 * A default visitor for types. All visitor methods except
3533 * visitType are implemented by delegating to visitType. Concrete
3534 * subclasses must provide an implementation of visitType and can
3535 * override other methods as needed.
3536 *
3537 * @param <R> the return type of the operation implemented by this
3538 * visitor; use Void if no return type is needed.
3539 * @param <S> the type of the second argument (the first being the
3540 * type itself) of the operation implemented by this visitor; use
3541 * Void if a second argument is not needed.
3542 */
3543 public static abstract class DefaultTypeVisitor<R,S> implements Type.Visitor<R,S> {
3544 final public R visit(Type t, S s) { return t.accept(this, s); }
3545 public R visitClassType(ClassType t, S s) { return visitType(t, s); }
3546 public R visitWildcardType(WildcardType t, S s) { return visitType(t, s); }
3547 public R visitArrayType(ArrayType t, S s) { return visitType(t, s); }
3548 public R visitMethodType(MethodType t, S s) { return visitType(t, s); }
3549 public R visitPackageType(PackageType t, S s) { return visitType(t, s); }
3550 public R visitTypeVar(TypeVar t, S s) { return visitType(t, s); }
3551 public R visitCapturedType(CapturedType t, S s) { return visitType(t, s); }
3552 public R visitForAll(ForAll t, S s) { return visitType(t, s); }
3553 public R visitUndetVar(UndetVar t, S s) { return visitType(t, s); }
3554 public R visitErrorType(ErrorType t, S s) { return visitType(t, s); }
3555 }
3557 /**
3558 * A default visitor for symbols. All visitor methods except
3559 * visitSymbol are implemented by delegating to visitSymbol. Concrete
3560 * subclasses must provide an implementation of visitSymbol and can
3561 * override other methods as needed.
3562 *
3563 * @param <R> the return type of the operation implemented by this
3564 * visitor; use Void if no return type is needed.
3565 * @param <S> the type of the second argument (the first being the
3566 * symbol itself) of the operation implemented by this visitor; use
3567 * Void if a second argument is not needed.
3568 */
3569 public static abstract class DefaultSymbolVisitor<R,S> implements Symbol.Visitor<R,S> {
3570 final public R visit(Symbol s, S arg) { return s.accept(this, arg); }
3571 public R visitClassSymbol(ClassSymbol s, S arg) { return visitSymbol(s, arg); }
3572 public R visitMethodSymbol(MethodSymbol s, S arg) { return visitSymbol(s, arg); }
3573 public R visitOperatorSymbol(OperatorSymbol s, S arg) { return visitSymbol(s, arg); }
3574 public R visitPackageSymbol(PackageSymbol s, S arg) { return visitSymbol(s, arg); }
3575 public R visitTypeSymbol(TypeSymbol s, S arg) { return visitSymbol(s, arg); }
3576 public R visitVarSymbol(VarSymbol s, S arg) { return visitSymbol(s, arg); }
3577 }
3579 /**
3580 * A <em>simple</em> visitor for types. This visitor is simple as
3581 * captured wildcards, for-all types (generic methods), and
3582 * undetermined type variables (part of inference) are hidden.
3583 * Captured wildcards are hidden by treating them as type
3584 * variables and the rest are hidden by visiting their qtypes.
3585 *
3586 * @param <R> the return type of the operation implemented by this
3587 * visitor; use Void if no return type is needed.
3588 * @param <S> the type of the second argument (the first being the
3589 * type itself) of the operation implemented by this visitor; use
3590 * Void if a second argument is not needed.
3591 */
3592 public static abstract class SimpleVisitor<R,S> extends DefaultTypeVisitor<R,S> {
3593 @Override
3594 public R visitCapturedType(CapturedType t, S s) {
3595 return visitTypeVar(t, s);
3596 }
3597 @Override
3598 public R visitForAll(ForAll t, S s) {
3599 return visit(t.qtype, s);
3600 }
3601 @Override
3602 public R visitUndetVar(UndetVar t, S s) {
3603 return visit(t.qtype, s);
3604 }
3605 }
3607 /**
3608 * A plain relation on types. That is a 2-ary function on the
3609 * form Type × Type → Boolean.
3610 * <!-- In plain text: Type x Type -> Boolean -->
3611 */
3612 public static abstract class TypeRelation extends SimpleVisitor<Boolean,Type> {}
3614 /**
3615 * A convenience visitor for implementing operations that only
3616 * require one argument (the type itself), that is, unary
3617 * operations.
3618 *
3619 * @param <R> the return type of the operation implemented by this
3620 * visitor; use Void if no return type is needed.
3621 */
3622 public static abstract class UnaryVisitor<R> extends SimpleVisitor<R,Void> {
3623 final public R visit(Type t) { return t.accept(this, null); }
3624 }
3626 /**
3627 * A visitor for implementing a mapping from types to types. The
3628 * default behavior of this class is to implement the identity
3629 * mapping (mapping a type to itself). This can be overridden in
3630 * subclasses.
3631 *
3632 * @param <S> the type of the second argument (the first being the
3633 * type itself) of this mapping; use Void if a second argument is
3634 * not needed.
3635 */
3636 public static class MapVisitor<S> extends DefaultTypeVisitor<Type,S> {
3637 final public Type visit(Type t) { return t.accept(this, null); }
3638 public Type visitType(Type t, S s) { return t; }
3639 }
3640 // </editor-fold>
3643 // <editor-fold defaultstate="collapsed" desc="Annotation support">
3645 public RetentionPolicy getRetention(Attribute.Compound a) {
3646 RetentionPolicy vis = RetentionPolicy.CLASS; // the default
3647 Attribute.Compound c = a.type.tsym.attribute(syms.retentionType.tsym);
3648 if (c != null) {
3649 Attribute value = c.member(names.value);
3650 if (value != null && value instanceof Attribute.Enum) {
3651 Name levelName = ((Attribute.Enum)value).value.name;
3652 if (levelName == names.SOURCE) vis = RetentionPolicy.SOURCE;
3653 else if (levelName == names.CLASS) vis = RetentionPolicy.CLASS;
3654 else if (levelName == names.RUNTIME) vis = RetentionPolicy.RUNTIME;
3655 else ;// /* fail soft */ throw new AssertionError(levelName);
3656 }
3657 }
3658 return vis;
3659 }
3660 // </editor-fold>
3661 }
