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src/share/classes/com/sun/tools/javac/code/Types.java@adaa3fc51b60
src/share/classes/com/sun/tools/javac/code/Types.java
Wed, 02 Apr 2008 11:44:23 +0100
- author
- mcimadamore
- date
- Wed, 02 Apr 2008 11:44:23 +0100
- changeset 19
- adaa3fc51b60
- parent 5
- b45f8d4794b7
- child 30
- a1d1f335633f
- permissions
- -rw-r--r--
6531090: Cannot access methods/fields of a captured type belonging to an intersection type
Summary: fixed lookup of field/methods on intersection types
Reviewed-by: jjg
1 /*
2 * Copyright 2003-2006 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
26 package com.sun.tools.javac.code;
28 import java.util.*;
30 import com.sun.tools.javac.util.*;
31 import com.sun.tools.javac.util.List;
33 import com.sun.tools.javac.jvm.ClassReader;
34 import com.sun.tools.javac.comp.Infer;
35 import com.sun.tools.javac.comp.Check;
37 import static com.sun.tools.javac.code.Type.*;
38 import static com.sun.tools.javac.code.TypeTags.*;
39 import static com.sun.tools.javac.code.Symbol.*;
40 import static com.sun.tools.javac.code.Flags.*;
41 import static com.sun.tools.javac.code.BoundKind.*;
42 import static com.sun.tools.javac.util.ListBuffer.lb;
44 /**
45 * Utility class containing various operations on types.
46 *
47 * <p>Unless other names are more illustrative, the following naming
48 * conventions should be observed in this file:
49 *
50 * <dl>
51 * <dt>t</dt>
52 * <dd>If the first argument to an operation is a type, it should be named t.</dd>
53 * <dt>s</dt>
54 * <dd>Similarly, if the second argument to an operation is a type, it should be named s.</dd>
55 * <dt>ts</dt>
56 * <dd>If an operations takes a list of types, the first should be named ts.</dd>
57 * <dt>ss</dt>
58 * <dd>A second list of types should be named ss.</dd>
59 * </dl>
60 *
61 * <p><b>This is NOT part of any API supported by Sun Microsystems.
62 * If you write code that depends on this, you do so at your own risk.
63 * This code and its internal interfaces are subject to change or
64 * deletion without notice.</b>
65 */
66 public class Types {
67 protected static final Context.Key<Types> typesKey =
68 new Context.Key<Types>();
70 final Symtab syms;
71 final Name.Table names;
72 final boolean allowBoxing;
73 final ClassReader reader;
74 final Source source;
75 final Check chk;
76 List<Warner> warnStack = List.nil();
77 final Name capturedName;
79 // <editor-fold defaultstate="collapsed" desc="Instantiating">
80 public static Types instance(Context context) {
81 Types instance = context.get(typesKey);
82 if (instance == null)
83 instance = new Types(context);
84 return instance;
85 }
87 protected Types(Context context) {
88 context.put(typesKey, this);
89 syms = Symtab.instance(context);
90 names = Name.Table.instance(context);
91 allowBoxing = Source.instance(context).allowBoxing();
92 reader = ClassReader.instance(context);
93 source = Source.instance(context);
94 chk = Check.instance(context);
95 capturedName = names.fromString("<captured wildcard>");
96 }
97 // </editor-fold>
99 // <editor-fold defaultstate="collapsed" desc="upperBound">
100 /**
101 * The "rvalue conversion".<br>
102 * The upper bound of most types is the type
103 * itself. Wildcards, on the other hand have upper
104 * and lower bounds.
105 * @param t a type
106 * @return the upper bound of the given type
107 */
108 public Type upperBound(Type t) {
109 return upperBound.visit(t);
110 }
111 // where
112 private final MapVisitor<Void> upperBound = new MapVisitor<Void>() {
114 @Override
115 public Type visitWildcardType(WildcardType t, Void ignored) {
116 if (t.isSuperBound())
117 return t.bound == null ? syms.objectType : t.bound.bound;
118 else
119 return visit(t.type);
120 }
122 @Override
123 public Type visitCapturedType(CapturedType t, Void ignored) {
124 return visit(t.bound);
125 }
126 };
127 // </editor-fold>
129 // <editor-fold defaultstate="collapsed" desc="lowerBound">
130 /**
131 * The "lvalue conversion".<br>
132 * The lower bound of most types is the type
133 * itself. Wildcards, on the other hand have upper
134 * and lower bounds.
135 * @param t a type
136 * @return the lower bound of the given type
137 */
138 public Type lowerBound(Type t) {
139 return lowerBound.visit(t);
140 }
141 // where
142 private final MapVisitor<Void> lowerBound = new MapVisitor<Void>() {
144 @Override
145 public Type visitWildcardType(WildcardType t, Void ignored) {
146 return t.isExtendsBound() ? syms.botType : visit(t.type);
147 }
149 @Override
150 public Type visitCapturedType(CapturedType t, Void ignored) {
151 return visit(t.getLowerBound());
152 }
153 };
154 // </editor-fold>
156 // <editor-fold defaultstate="collapsed" desc="isUnbounded">
157 /**
158 * Checks that all the arguments to a class are unbounded
159 * wildcards or something else that doesn't make any restrictions
160 * on the arguments. If a class isUnbounded, a raw super- or
161 * subclass can be cast to it without a warning.
162 * @param t a type
163 * @return true iff the given type is unbounded or raw
164 */
165 public boolean isUnbounded(Type t) {
166 return isUnbounded.visit(t);
167 }
168 // where
169 private final UnaryVisitor<Boolean> isUnbounded = new UnaryVisitor<Boolean>() {
171 public Boolean visitType(Type t, Void ignored) {
172 return true;
173 }
175 @Override
176 public Boolean visitClassType(ClassType t, Void ignored) {
177 List<Type> parms = t.tsym.type.allparams();
178 List<Type> args = t.allparams();
179 while (parms.nonEmpty()) {
180 WildcardType unb = new WildcardType(syms.objectType,
181 BoundKind.UNBOUND,
182 syms.boundClass,
183 (TypeVar)parms.head);
184 if (!containsType(args.head, unb))
185 return false;
186 parms = parms.tail;
187 args = args.tail;
188 }
189 return true;
190 }
191 };
192 // </editor-fold>
194 // <editor-fold defaultstate="collapsed" desc="asSub">
195 /**
196 * Return the least specific subtype of t that starts with symbol
197 * sym. If none exists, return null. The least specific subtype
198 * is determined as follows:
199 *
200 * <p>If there is exactly one parameterized instance of sym that is a
201 * subtype of t, that parameterized instance is returned.<br>
202 * Otherwise, if the plain type or raw type `sym' is a subtype of
203 * type t, the type `sym' itself is returned. Otherwise, null is
204 * returned.
205 */
206 public Type asSub(Type t, Symbol sym) {
207 return asSub.visit(t, sym);
208 }
209 // where
210 private final SimpleVisitor<Type,Symbol> asSub = new SimpleVisitor<Type,Symbol>() {
212 public Type visitType(Type t, Symbol sym) {
213 return null;
214 }
216 @Override
217 public Type visitClassType(ClassType t, Symbol sym) {
218 if (t.tsym == sym)
219 return t;
220 Type base = asSuper(sym.type, t.tsym);
221 if (base == null)
222 return null;
223 ListBuffer<Type> from = new ListBuffer<Type>();
224 ListBuffer<Type> to = new ListBuffer<Type>();
225 try {
226 adapt(base, t, from, to);
227 } catch (AdaptFailure ex) {
228 return null;
229 }
230 Type res = subst(sym.type, from.toList(), to.toList());
231 if (!isSubtype(res, t))
232 return null;
233 ListBuffer<Type> openVars = new ListBuffer<Type>();
234 for (List<Type> l = sym.type.allparams();
235 l.nonEmpty(); l = l.tail)
236 if (res.contains(l.head) && !t.contains(l.head))
237 openVars.append(l.head);
238 if (openVars.nonEmpty()) {
239 if (t.isRaw()) {
240 // The subtype of a raw type is raw
241 res = erasure(res);
242 } else {
243 // Unbound type arguments default to ?
244 List<Type> opens = openVars.toList();
245 ListBuffer<Type> qs = new ListBuffer<Type>();
246 for (List<Type> iter = opens; iter.nonEmpty(); iter = iter.tail) {
247 qs.append(new WildcardType(syms.objectType, BoundKind.UNBOUND, syms.boundClass, (TypeVar) iter.head));
248 }
249 res = subst(res, opens, qs.toList());
250 }
251 }
252 return res;
253 }
255 @Override
256 public Type visitErrorType(ErrorType t, Symbol sym) {
257 return t;
258 }
259 };
260 // </editor-fold>
262 // <editor-fold defaultstate="collapsed" desc="isConvertible">
263 /**
264 * Is t a subtype of or convertiable via boxing/unboxing
265 * convertions to s?
266 */
267 public boolean isConvertible(Type t, Type s, Warner warn) {
268 boolean tPrimitive = t.isPrimitive();
269 boolean sPrimitive = s.isPrimitive();
270 if (tPrimitive == sPrimitive)
271 return isSubtypeUnchecked(t, s, warn);
272 if (!allowBoxing) return false;
273 return tPrimitive
274 ? isSubtype(boxedClass(t).type, s)
275 : isSubtype(unboxedType(t), s);
276 }
278 /**
279 * Is t a subtype of or convertiable via boxing/unboxing
280 * convertions to s?
281 */
282 public boolean isConvertible(Type t, Type s) {
283 return isConvertible(t, s, Warner.noWarnings);
284 }
285 // </editor-fold>
287 // <editor-fold defaultstate="collapsed" desc="isSubtype">
288 /**
289 * Is t an unchecked subtype of s?
290 */
291 public boolean isSubtypeUnchecked(Type t, Type s) {
292 return isSubtypeUnchecked(t, s, Warner.noWarnings);
293 }
294 /**
295 * Is t an unchecked subtype of s?
296 */
297 public boolean isSubtypeUnchecked(Type t, Type s, Warner warn) {
298 if (t.tag == ARRAY && s.tag == ARRAY) {
299 return (((ArrayType)t).elemtype.tag <= lastBaseTag)
300 ? isSameType(elemtype(t), elemtype(s))
301 : isSubtypeUnchecked(elemtype(t), elemtype(s), warn);
302 } else if (isSubtype(t, s)) {
303 return true;
304 } else if (!s.isRaw()) {
305 Type t2 = asSuper(t, s.tsym);
306 if (t2 != null && t2.isRaw()) {
307 if (isReifiable(s))
308 warn.silentUnchecked();
309 else
310 warn.warnUnchecked();
311 return true;
312 }
313 }
314 return false;
315 }
317 /**
318 * Is t a subtype of s?<br>
319 * (not defined for Method and ForAll types)
320 */
321 final public boolean isSubtype(Type t, Type s) {
322 return isSubtype(t, s, true);
323 }
324 final public boolean isSubtypeNoCapture(Type t, Type s) {
325 return isSubtype(t, s, false);
326 }
327 public boolean isSubtype(Type t, Type s, boolean capture) {
328 if (t == s)
329 return true;
331 if (s.tag >= firstPartialTag)
332 return isSuperType(s, t);
334 Type lower = lowerBound(s);
335 if (s != lower)
336 return isSubtype(capture ? capture(t) : t, lower, false);
338 return isSubtype.visit(capture ? capture(t) : t, s);
339 }
340 // where
341 private TypeRelation isSubtype = new TypeRelation()
342 {
343 public Boolean visitType(Type t, Type s) {
344 switch (t.tag) {
345 case BYTE: case CHAR:
346 return (t.tag == s.tag ||
347 t.tag + 2 <= s.tag && s.tag <= DOUBLE);
348 case SHORT: case INT: case LONG: case FLOAT: case DOUBLE:
349 return t.tag <= s.tag && s.tag <= DOUBLE;
350 case BOOLEAN: case VOID:
351 return t.tag == s.tag;
352 case TYPEVAR:
353 return isSubtypeNoCapture(t.getUpperBound(), s);
354 case BOT:
355 return
356 s.tag == BOT || s.tag == CLASS ||
357 s.tag == ARRAY || s.tag == TYPEVAR;
358 case NONE:
359 return false;
360 default:
361 throw new AssertionError("isSubtype " + t.tag);
362 }
363 }
365 private Set<TypePair> cache = new HashSet<TypePair>();
367 private boolean containsTypeRecursive(Type t, Type s) {
368 TypePair pair = new TypePair(t, s);
369 if (cache.add(pair)) {
370 try {
371 return containsType(t.getTypeArguments(),
372 s.getTypeArguments());
373 } finally {
374 cache.remove(pair);
375 }
376 } else {
377 return containsType(t.getTypeArguments(),
378 rewriteSupers(s).getTypeArguments());
379 }
380 }
382 private Type rewriteSupers(Type t) {
383 if (!t.isParameterized())
384 return t;
385 ListBuffer<Type> from = lb();
386 ListBuffer<Type> to = lb();
387 adaptSelf(t, from, to);
388 if (from.isEmpty())
389 return t;
390 ListBuffer<Type> rewrite = lb();
391 boolean changed = false;
392 for (Type orig : to.toList()) {
393 Type s = rewriteSupers(orig);
394 if (s.isSuperBound() && !s.isExtendsBound()) {
395 s = new WildcardType(syms.objectType,
396 BoundKind.UNBOUND,
397 syms.boundClass);
398 changed = true;
399 } else if (s != orig) {
400 s = new WildcardType(upperBound(s),
401 BoundKind.EXTENDS,
402 syms.boundClass);
403 changed = true;
404 }
405 rewrite.append(s);
406 }
407 if (changed)
408 return subst(t.tsym.type, from.toList(), rewrite.toList());
409 else
410 return t;
411 }
413 @Override
414 public Boolean visitClassType(ClassType t, Type s) {
415 Type sup = asSuper(t, s.tsym);
416 return sup != null
417 && sup.tsym == s.tsym
418 // You're not allowed to write
419 // Vector<Object> vec = new Vector<String>();
420 // But with wildcards you can write
421 // Vector<? extends Object> vec = new Vector<String>();
422 // which means that subtype checking must be done
423 // here instead of same-type checking (via containsType).
424 && (!s.isParameterized() || containsTypeRecursive(s, sup))
425 && isSubtypeNoCapture(sup.getEnclosingType(),
426 s.getEnclosingType());
427 }
429 @Override
430 public Boolean visitArrayType(ArrayType t, Type s) {
431 if (s.tag == ARRAY) {
432 if (t.elemtype.tag <= lastBaseTag)
433 return isSameType(t.elemtype, elemtype(s));
434 else
435 return isSubtypeNoCapture(t.elemtype, elemtype(s));
436 }
438 if (s.tag == CLASS) {
439 Name sname = s.tsym.getQualifiedName();
440 return sname == names.java_lang_Object
441 || sname == names.java_lang_Cloneable
442 || sname == names.java_io_Serializable;
443 }
445 return false;
446 }
448 @Override
449 public Boolean visitUndetVar(UndetVar t, Type s) {
450 //todo: test against origin needed? or replace with substitution?
451 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
452 return true;
454 if (t.inst != null)
455 return isSubtypeNoCapture(t.inst, s); // TODO: ", warn"?
457 t.hibounds = t.hibounds.prepend(s);
458 return true;
459 }
461 @Override
462 public Boolean visitErrorType(ErrorType t, Type s) {
463 return true;
464 }
465 };
467 /**
468 * Is t a subtype of every type in given list `ts'?<br>
469 * (not defined for Method and ForAll types)<br>
470 * Allows unchecked conversions.
471 */
472 public boolean isSubtypeUnchecked(Type t, List<Type> ts, Warner warn) {
473 for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
474 if (!isSubtypeUnchecked(t, l.head, warn))
475 return false;
476 return true;
477 }
479 /**
480 * Are corresponding elements of ts subtypes of ss? If lists are
481 * of different length, return false.
482 */
483 public boolean isSubtypes(List<Type> ts, List<Type> ss) {
484 while (ts.tail != null && ss.tail != null
485 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
486 isSubtype(ts.head, ss.head)) {
487 ts = ts.tail;
488 ss = ss.tail;
489 }
490 return ts.tail == null && ss.tail == null;
491 /*inlined: ts.isEmpty() && ss.isEmpty();*/
492 }
494 /**
495 * Are corresponding elements of ts subtypes of ss, allowing
496 * unchecked conversions? If lists are of different length,
497 * return false.
498 **/
499 public boolean isSubtypesUnchecked(List<Type> ts, List<Type> ss, Warner warn) {
500 while (ts.tail != null && ss.tail != null
501 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
502 isSubtypeUnchecked(ts.head, ss.head, warn)) {
503 ts = ts.tail;
504 ss = ss.tail;
505 }
506 return ts.tail == null && ss.tail == null;
507 /*inlined: ts.isEmpty() && ss.isEmpty();*/
508 }
509 // </editor-fold>
511 // <editor-fold defaultstate="collapsed" desc="isSuperType">
512 /**
513 * Is t a supertype of s?
514 */
515 public boolean isSuperType(Type t, Type s) {
516 switch (t.tag) {
517 case ERROR:
518 return true;
519 case UNDETVAR: {
520 UndetVar undet = (UndetVar)t;
521 if (t == s ||
522 undet.qtype == s ||
523 s.tag == ERROR ||
524 s.tag == BOT) return true;
525 if (undet.inst != null)
526 return isSubtype(s, undet.inst);
527 undet.lobounds = undet.lobounds.prepend(s);
528 return true;
529 }
530 default:
531 return isSubtype(s, t);
532 }
533 }
534 // </editor-fold>
536 // <editor-fold defaultstate="collapsed" desc="isSameType">
537 /**
538 * Are corresponding elements of the lists the same type? If
539 * lists are of different length, return false.
540 */
541 public boolean isSameTypes(List<Type> ts, List<Type> ss) {
542 while (ts.tail != null && ss.tail != null
543 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
544 isSameType(ts.head, ss.head)) {
545 ts = ts.tail;
546 ss = ss.tail;
547 }
548 return ts.tail == null && ss.tail == null;
549 /*inlined: ts.isEmpty() && ss.isEmpty();*/
550 }
552 /**
553 * Is t the same type as s?
554 */
555 public boolean isSameType(Type t, Type s) {
556 return isSameType.visit(t, s);
557 }
558 // where
559 private TypeRelation isSameType = new TypeRelation() {
561 public Boolean visitType(Type t, Type s) {
562 if (t == s)
563 return true;
565 if (s.tag >= firstPartialTag)
566 return visit(s, t);
568 switch (t.tag) {
569 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
570 case DOUBLE: case BOOLEAN: case VOID: case BOT: case NONE:
571 return t.tag == s.tag;
572 case TYPEVAR:
573 return s.isSuperBound()
574 && !s.isExtendsBound()
575 && visit(t, upperBound(s));
576 default:
577 throw new AssertionError("isSameType " + t.tag);
578 }
579 }
581 @Override
582 public Boolean visitWildcardType(WildcardType t, Type s) {
583 if (s.tag >= firstPartialTag)
584 return visit(s, t);
585 else
586 return false;
587 }
589 @Override
590 public Boolean visitClassType(ClassType t, Type s) {
591 if (t == s)
592 return true;
594 if (s.tag >= firstPartialTag)
595 return visit(s, t);
597 if (s.isSuperBound() && !s.isExtendsBound())
598 return visit(t, upperBound(s)) && visit(t, lowerBound(s));
600 if (t.isCompound() && s.isCompound()) {
601 if (!visit(supertype(t), supertype(s)))
602 return false;
604 HashSet<SingletonType> set = new HashSet<SingletonType>();
605 for (Type x : interfaces(t))
606 set.add(new SingletonType(x));
607 for (Type x : interfaces(s)) {
608 if (!set.remove(new SingletonType(x)))
609 return false;
610 }
611 return (set.size() == 0);
612 }
613 return t.tsym == s.tsym
614 && visit(t.getEnclosingType(), s.getEnclosingType())
615 && containsTypeEquivalent(t.getTypeArguments(), s.getTypeArguments());
616 }
618 @Override
619 public Boolean visitArrayType(ArrayType t, Type s) {
620 if (t == s)
621 return true;
623 if (s.tag >= firstPartialTag)
624 return visit(s, t);
626 return s.tag == ARRAY
627 && containsTypeEquivalent(t.elemtype, elemtype(s));
628 }
630 @Override
631 public Boolean visitMethodType(MethodType t, Type s) {
632 // isSameType for methods does not take thrown
633 // exceptions into account!
634 return hasSameArgs(t, s) && visit(t.getReturnType(), s.getReturnType());
635 }
637 @Override
638 public Boolean visitPackageType(PackageType t, Type s) {
639 return t == s;
640 }
642 @Override
643 public Boolean visitForAll(ForAll t, Type s) {
644 if (s.tag != FORALL)
645 return false;
647 ForAll forAll = (ForAll)s;
648 return hasSameBounds(t, forAll)
649 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
650 }
652 @Override
653 public Boolean visitUndetVar(UndetVar t, Type s) {
654 if (s.tag == WILDCARD)
655 // FIXME, this might be leftovers from before capture conversion
656 return false;
658 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
659 return true;
661 if (t.inst != null)
662 return visit(t.inst, s);
664 t.inst = fromUnknownFun.apply(s);
665 for (List<Type> l = t.lobounds; l.nonEmpty(); l = l.tail) {
666 if (!isSubtype(l.head, t.inst))
667 return false;
668 }
669 for (List<Type> l = t.hibounds; l.nonEmpty(); l = l.tail) {
670 if (!isSubtype(t.inst, l.head))
671 return false;
672 }
673 return true;
674 }
676 @Override
677 public Boolean visitErrorType(ErrorType t, Type s) {
678 return true;
679 }
680 };
681 // </editor-fold>
683 // <editor-fold defaultstate="collapsed" desc="fromUnknownFun">
684 /**
685 * A mapping that turns all unknown types in this type to fresh
686 * unknown variables.
687 */
688 public Mapping fromUnknownFun = new Mapping("fromUnknownFun") {
689 public Type apply(Type t) {
690 if (t.tag == UNKNOWN) return new UndetVar(t);
691 else return t.map(this);
692 }
693 };
694 // </editor-fold>
696 // <editor-fold defaultstate="collapsed" desc="Contains Type">
697 public boolean containedBy(Type t, Type s) {
698 switch (t.tag) {
699 case UNDETVAR:
700 if (s.tag == WILDCARD) {
701 UndetVar undetvar = (UndetVar)t;
703 // Because of wildcard capture, s must be on the left
704 // hand side of an assignment. Furthermore, t is an
705 // underconstrained type variable, for example, one
706 // that is only used in the return type of a method.
707 // If the type variable is truly underconstrained, it
708 // cannot have any low bounds:
709 assert undetvar.lobounds.isEmpty() : undetvar;
711 undetvar.inst = glb(upperBound(s), undetvar.inst);
712 return true;
713 } else {
714 return isSameType(t, s);
715 }
716 case ERROR:
717 return true;
718 default:
719 return containsType(s, t);
720 }
721 }
723 boolean containsType(List<Type> ts, List<Type> ss) {
724 while (ts.nonEmpty() && ss.nonEmpty()
725 && containsType(ts.head, ss.head)) {
726 ts = ts.tail;
727 ss = ss.tail;
728 }
729 return ts.isEmpty() && ss.isEmpty();
730 }
732 /**
733 * Check if t contains s.
734 *
735 * <p>T contains S if:
736 *
737 * <p>{@code L(T) <: L(S) && U(S) <: U(T)}
738 *
739 * <p>This relation is only used by ClassType.isSubtype(), that
740 * is,
741 *
742 * <p>{@code C<S> <: C<T> if T contains S.}
743 *
744 * <p>Because of F-bounds, this relation can lead to infinite
745 * recursion. Thus we must somehow break that recursion. Notice
746 * that containsType() is only called from ClassType.isSubtype().
747 * Since the arguments have already been checked against their
748 * bounds, we know:
749 *
750 * <p>{@code U(S) <: U(T) if T is "super" bound (U(T) *is* the bound)}
751 *
752 * <p>{@code L(T) <: L(S) if T is "extends" bound (L(T) is bottom)}
753 *
754 * @param t a type
755 * @param s a type
756 */
757 public boolean containsType(Type t, Type s) {
758 return containsType.visit(t, s);
759 }
760 // where
761 private TypeRelation containsType = new TypeRelation() {
763 private Type U(Type t) {
764 while (t.tag == WILDCARD) {
765 WildcardType w = (WildcardType)t;
766 if (w.isSuperBound())
767 return w.bound == null ? syms.objectType : w.bound.bound;
768 else
769 t = w.type;
770 }
771 return t;
772 }
774 private Type L(Type t) {
775 while (t.tag == WILDCARD) {
776 WildcardType w = (WildcardType)t;
777 if (w.isExtendsBound())
778 return syms.botType;
779 else
780 t = w.type;
781 }
782 return t;
783 }
785 public Boolean visitType(Type t, Type s) {
786 if (s.tag >= firstPartialTag)
787 return containedBy(s, t);
788 else
789 return isSameType(t, s);
790 }
792 void debugContainsType(WildcardType t, Type s) {
793 System.err.println();
794 System.err.format(" does %s contain %s?%n", t, s);
795 System.err.format(" %s U(%s) <: U(%s) %s = %s%n",
796 upperBound(s), s, t, U(t),
797 t.isSuperBound()
798 || isSubtypeNoCapture(upperBound(s), U(t)));
799 System.err.format(" %s L(%s) <: L(%s) %s = %s%n",
800 L(t), t, s, lowerBound(s),
801 t.isExtendsBound()
802 || isSubtypeNoCapture(L(t), lowerBound(s)));
803 System.err.println();
804 }
806 @Override
807 public Boolean visitWildcardType(WildcardType t, Type s) {
808 if (s.tag >= firstPartialTag)
809 return containedBy(s, t);
810 else {
811 // debugContainsType(t, s);
812 return isSameWildcard(t, s)
813 || isCaptureOf(s, t)
814 || ((t.isExtendsBound() || isSubtypeNoCapture(L(t), lowerBound(s))) &&
815 (t.isSuperBound() || isSubtypeNoCapture(upperBound(s), U(t))));
816 }
817 }
819 @Override
820 public Boolean visitUndetVar(UndetVar t, Type s) {
821 if (s.tag != WILDCARD)
822 return isSameType(t, s);
823 else
824 return false;
825 }
827 @Override
828 public Boolean visitErrorType(ErrorType t, Type s) {
829 return true;
830 }
831 };
833 public boolean isCaptureOf(Type s, WildcardType t) {
834 if (s.tag != TYPEVAR || !(s instanceof CapturedType))
835 return false;
836 return isSameWildcard(t, ((CapturedType)s).wildcard);
837 }
839 public boolean isSameWildcard(WildcardType t, Type s) {
840 if (s.tag != WILDCARD)
841 return false;
842 WildcardType w = (WildcardType)s;
843 return w.kind == t.kind && w.type == t.type;
844 }
846 public boolean containsTypeEquivalent(List<Type> ts, List<Type> ss) {
847 while (ts.nonEmpty() && ss.nonEmpty()
848 && containsTypeEquivalent(ts.head, ss.head)) {
849 ts = ts.tail;
850 ss = ss.tail;
851 }
852 return ts.isEmpty() && ss.isEmpty();
853 }
854 // </editor-fold>
856 // <editor-fold defaultstate="collapsed" desc="isCastable">
857 public boolean isCastable(Type t, Type s) {
858 return isCastable(t, s, Warner.noWarnings);
859 }
861 /**
862 * Is t is castable to s?<br>
863 * s is assumed to be an erased type.<br>
864 * (not defined for Method and ForAll types).
865 */
866 public boolean isCastable(Type t, Type s, Warner warn) {
867 if (t == s)
868 return true;
870 if (t.isPrimitive() != s.isPrimitive())
871 return allowBoxing && isConvertible(t, s, warn);
873 if (warn != warnStack.head) {
874 try {
875 warnStack = warnStack.prepend(warn);
876 return isCastable.visit(t, s);
877 } finally {
878 warnStack = warnStack.tail;
879 }
880 } else {
881 return isCastable.visit(t, s);
882 }
883 }
884 // where
885 private TypeRelation isCastable = new TypeRelation() {
887 public Boolean visitType(Type t, Type s) {
888 if (s.tag == ERROR)
889 return true;
891 switch (t.tag) {
892 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
893 case DOUBLE:
894 return s.tag <= DOUBLE;
895 case BOOLEAN:
896 return s.tag == BOOLEAN;
897 case VOID:
898 return false;
899 case BOT:
900 return isSubtype(t, s);
901 default:
902 throw new AssertionError();
903 }
904 }
906 @Override
907 public Boolean visitWildcardType(WildcardType t, Type s) {
908 return isCastable(upperBound(t), s, warnStack.head);
909 }
911 @Override
912 public Boolean visitClassType(ClassType t, Type s) {
913 if (s.tag == ERROR || s.tag == BOT)
914 return true;
916 if (s.tag == TYPEVAR) {
917 if (isCastable(s.getUpperBound(), t, Warner.noWarnings)) {
918 warnStack.head.warnUnchecked();
919 return true;
920 } else {
921 return false;
922 }
923 }
925 if (t.isCompound()) {
926 if (!visit(supertype(t), s))
927 return false;
928 for (Type intf : interfaces(t)) {
929 if (!visit(intf, s))
930 return false;
931 }
932 return true;
933 }
935 if (s.isCompound()) {
936 // call recursively to reuse the above code
937 return visitClassType((ClassType)s, t);
938 }
940 if (s.tag == CLASS || s.tag == ARRAY) {
941 boolean upcast;
942 if ((upcast = isSubtype(erasure(t), erasure(s)))
943 || isSubtype(erasure(s), erasure(t))) {
944 if (!upcast && s.tag == ARRAY) {
945 if (!isReifiable(s))
946 warnStack.head.warnUnchecked();
947 return true;
948 } else if (s.isRaw()) {
949 return true;
950 } else if (t.isRaw()) {
951 if (!isUnbounded(s))
952 warnStack.head.warnUnchecked();
953 return true;
954 }
955 // Assume |a| <: |b|
956 final Type a = upcast ? t : s;
957 final Type b = upcast ? s : t;
958 final boolean HIGH = true;
959 final boolean LOW = false;
960 final boolean DONT_REWRITE_TYPEVARS = false;
961 Type aHigh = rewriteQuantifiers(a, HIGH, DONT_REWRITE_TYPEVARS);
962 Type aLow = rewriteQuantifiers(a, LOW, DONT_REWRITE_TYPEVARS);
963 Type bHigh = rewriteQuantifiers(b, HIGH, DONT_REWRITE_TYPEVARS);
964 Type bLow = rewriteQuantifiers(b, LOW, DONT_REWRITE_TYPEVARS);
965 Type lowSub = asSub(bLow, aLow.tsym);
966 Type highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
967 if (highSub == null) {
968 final boolean REWRITE_TYPEVARS = true;
969 aHigh = rewriteQuantifiers(a, HIGH, REWRITE_TYPEVARS);
970 aLow = rewriteQuantifiers(a, LOW, REWRITE_TYPEVARS);
971 bHigh = rewriteQuantifiers(b, HIGH, REWRITE_TYPEVARS);
972 bLow = rewriteQuantifiers(b, LOW, REWRITE_TYPEVARS);
973 lowSub = asSub(bLow, aLow.tsym);
974 highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
975 }
976 if (highSub != null) {
977 assert a.tsym == highSub.tsym && a.tsym == lowSub.tsym
978 : a.tsym + " != " + highSub.tsym + " != " + lowSub.tsym;
979 if (!disjointTypes(aHigh.getTypeArguments(), highSub.getTypeArguments())
980 && !disjointTypes(aHigh.getTypeArguments(), lowSub.getTypeArguments())
981 && !disjointTypes(aLow.getTypeArguments(), highSub.getTypeArguments())
982 && !disjointTypes(aLow.getTypeArguments(), lowSub.getTypeArguments())) {
983 if (upcast ? giveWarning(a, highSub) || giveWarning(a, lowSub)
984 : giveWarning(highSub, a) || giveWarning(lowSub, a))
985 warnStack.head.warnUnchecked();
986 return true;
987 }
988 }
989 if (isReifiable(s))
990 return isSubtypeUnchecked(a, b);
991 else
992 return isSubtypeUnchecked(a, b, warnStack.head);
993 }
995 // Sidecast
996 if (s.tag == CLASS) {
997 if ((s.tsym.flags() & INTERFACE) != 0) {
998 return ((t.tsym.flags() & FINAL) == 0)
999 ? sideCast(t, s, warnStack.head)
1000 : sideCastFinal(t, s, warnStack.head);
1001 } else if ((t.tsym.flags() & INTERFACE) != 0) {
1002 return ((s.tsym.flags() & FINAL) == 0)
1003 ? sideCast(t, s, warnStack.head)
1004 : sideCastFinal(t, s, warnStack.head);
1005 } else {
1006 // unrelated class types
1007 return false;
1008 }
1009 }
1010 }
1011 return false;
1012 }
1014 @Override
1015 public Boolean visitArrayType(ArrayType t, Type s) {
1016 switch (s.tag) {
1017 case ERROR:
1018 case BOT:
1019 return true;
1020 case TYPEVAR:
1021 if (isCastable(s, t, Warner.noWarnings)) {
1022 warnStack.head.warnUnchecked();
1023 return true;
1024 } else {
1025 return false;
1026 }
1027 case CLASS:
1028 return isSubtype(t, s);
1029 case ARRAY:
1030 if (elemtype(t).tag <= lastBaseTag) {
1031 return elemtype(t).tag == elemtype(s).tag;
1032 } else {
1033 return visit(elemtype(t), elemtype(s));
1034 }
1035 default:
1036 return false;
1037 }
1038 }
1040 @Override
1041 public Boolean visitTypeVar(TypeVar t, Type s) {
1042 switch (s.tag) {
1043 case ERROR:
1044 case BOT:
1045 return true;
1046 case TYPEVAR:
1047 if (isSubtype(t, s)) {
1048 return true;
1049 } else if (isCastable(t.bound, s, Warner.noWarnings)) {
1050 warnStack.head.warnUnchecked();
1051 return true;
1052 } else {
1053 return false;
1054 }
1055 default:
1056 return isCastable(t.bound, s, warnStack.head);
1057 }
1058 }
1060 @Override
1061 public Boolean visitErrorType(ErrorType t, Type s) {
1062 return true;
1063 }
1064 };
1065 // </editor-fold>
1067 // <editor-fold defaultstate="collapsed" desc="disjointTypes">
1068 public boolean disjointTypes(List<Type> ts, List<Type> ss) {
1069 while (ts.tail != null && ss.tail != null) {
1070 if (disjointType(ts.head, ss.head)) return true;
1071 ts = ts.tail;
1072 ss = ss.tail;
1073 }
1074 return false;
1075 }
1077 /**
1078 * Two types or wildcards are considered disjoint if it can be
1079 * proven that no type can be contained in both. It is
1080 * conservative in that it is allowed to say that two types are
1081 * not disjoint, even though they actually are.
1082 *
1083 * The type C<X> is castable to C<Y> exactly if X and Y are not
1084 * disjoint.
1085 */
1086 public boolean disjointType(Type t, Type s) {
1087 return disjointType.visit(t, s);
1088 }
1089 // where
1090 private TypeRelation disjointType = new TypeRelation() {
1092 private Set<TypePair> cache = new HashSet<TypePair>();
1094 public Boolean visitType(Type t, Type s) {
1095 if (s.tag == WILDCARD)
1096 return visit(s, t);
1097 else
1098 return notSoftSubtypeRecursive(t, s) || notSoftSubtypeRecursive(s, t);
1099 }
1101 private boolean isCastableRecursive(Type t, Type s) {
1102 TypePair pair = new TypePair(t, s);
1103 if (cache.add(pair)) {
1104 try {
1105 return Types.this.isCastable(t, s);
1106 } finally {
1107 cache.remove(pair);
1108 }
1109 } else {
1110 return true;
1111 }
1112 }
1114 private boolean notSoftSubtypeRecursive(Type t, Type s) {
1115 TypePair pair = new TypePair(t, s);
1116 if (cache.add(pair)) {
1117 try {
1118 return Types.this.notSoftSubtype(t, s);
1119 } finally {
1120 cache.remove(pair);
1121 }
1122 } else {
1123 return false;
1124 }
1125 }
1127 @Override
1128 public Boolean visitWildcardType(WildcardType t, Type s) {
1129 if (t.isUnbound())
1130 return false;
1132 if (s.tag != WILDCARD) {
1133 if (t.isExtendsBound())
1134 return notSoftSubtypeRecursive(s, t.type);
1135 else // isSuperBound()
1136 return notSoftSubtypeRecursive(t.type, s);
1137 }
1139 if (s.isUnbound())
1140 return false;
1142 if (t.isExtendsBound()) {
1143 if (s.isExtendsBound())
1144 return !isCastableRecursive(t.type, upperBound(s));
1145 else if (s.isSuperBound())
1146 return notSoftSubtypeRecursive(lowerBound(s), t.type);
1147 } else if (t.isSuperBound()) {
1148 if (s.isExtendsBound())
1149 return notSoftSubtypeRecursive(t.type, upperBound(s));
1150 }
1151 return false;
1152 }
1153 };
1154 // </editor-fold>
1156 // <editor-fold defaultstate="collapsed" desc="lowerBoundArgtypes">
1157 /**
1158 * Returns the lower bounds of the formals of a method.
1159 */
1160 public List<Type> lowerBoundArgtypes(Type t) {
1161 return map(t.getParameterTypes(), lowerBoundMapping);
1162 }
1163 private final Mapping lowerBoundMapping = new Mapping("lowerBound") {
1164 public Type apply(Type t) {
1165 return lowerBound(t);
1166 }
1167 };
1168 // </editor-fold>
1170 // <editor-fold defaultstate="collapsed" desc="notSoftSubtype">
1171 /**
1172 * This relation answers the question: is impossible that
1173 * something of type `t' can be a subtype of `s'? This is
1174 * different from the question "is `t' not a subtype of `s'?"
1175 * when type variables are involved: Integer is not a subtype of T
1176 * where <T extends Number> but it is not true that Integer cannot
1177 * possibly be a subtype of T.
1178 */
1179 public boolean notSoftSubtype(Type t, Type s) {
1180 if (t == s) return false;
1181 if (t.tag == TYPEVAR) {
1182 TypeVar tv = (TypeVar) t;
1183 if (s.tag == TYPEVAR)
1184 s = s.getUpperBound();
1185 return !isCastable(tv.bound,
1186 s,
1187 Warner.noWarnings);
1188 }
1189 if (s.tag != WILDCARD)
1190 s = upperBound(s);
1191 if (s.tag == TYPEVAR)
1192 s = s.getUpperBound();
1193 return !isSubtype(t, s);
1194 }
1195 // </editor-fold>
1197 // <editor-fold defaultstate="collapsed" desc="isReifiable">
1198 public boolean isReifiable(Type t) {
1199 return isReifiable.visit(t);
1200 }
1201 // where
1202 private UnaryVisitor<Boolean> isReifiable = new UnaryVisitor<Boolean>() {
1204 public Boolean visitType(Type t, Void ignored) {
1205 return true;
1206 }
1208 @Override
1209 public Boolean visitClassType(ClassType t, Void ignored) {
1210 if (!t.isParameterized())
1211 return true;
1213 for (Type param : t.allparams()) {
1214 if (!param.isUnbound())
1215 return false;
1216 }
1217 return true;
1218 }
1220 @Override
1221 public Boolean visitArrayType(ArrayType t, Void ignored) {
1222 return visit(t.elemtype);
1223 }
1225 @Override
1226 public Boolean visitTypeVar(TypeVar t, Void ignored) {
1227 return false;
1228 }
1229 };
1230 // </editor-fold>
1232 // <editor-fold defaultstate="collapsed" desc="Array Utils">
1233 public boolean isArray(Type t) {
1234 while (t.tag == WILDCARD)
1235 t = upperBound(t);
1236 return t.tag == ARRAY;
1237 }
1239 /**
1240 * The element type of an array.
1241 */
1242 public Type elemtype(Type t) {
1243 switch (t.tag) {
1244 case WILDCARD:
1245 return elemtype(upperBound(t));
1246 case ARRAY:
1247 return ((ArrayType)t).elemtype;
1248 case FORALL:
1249 return elemtype(((ForAll)t).qtype);
1250 case ERROR:
1251 return t;
1252 default:
1253 return null;
1254 }
1255 }
1257 /**
1258 * Mapping to take element type of an arraytype
1259 */
1260 private Mapping elemTypeFun = new Mapping ("elemTypeFun") {
1261 public Type apply(Type t) { return elemtype(t); }
1262 };
1264 /**
1265 * The number of dimensions of an array type.
1266 */
1267 public int dimensions(Type t) {
1268 int result = 0;
1269 while (t.tag == ARRAY) {
1270 result++;
1271 t = elemtype(t);
1272 }
1273 return result;
1274 }
1275 // </editor-fold>
1277 // <editor-fold defaultstate="collapsed" desc="asSuper">
1278 /**
1279 * Return the (most specific) base type of t that starts with the
1280 * given symbol. If none exists, return null.
1281 *
1282 * @param t a type
1283 * @param sym a symbol
1284 */
1285 public Type asSuper(Type t, Symbol sym) {
1286 return asSuper.visit(t, sym);
1287 }
1288 // where
1289 private SimpleVisitor<Type,Symbol> asSuper = new SimpleVisitor<Type,Symbol>() {
1291 public Type visitType(Type t, Symbol sym) {
1292 return null;
1293 }
1295 @Override
1296 public Type visitClassType(ClassType t, Symbol sym) {
1297 if (t.tsym == sym)
1298 return t;
1300 Type st = supertype(t);
1301 if (st.tag == CLASS || st.tag == TYPEVAR || st.tag == ERROR) {
1302 Type x = asSuper(st, sym);
1303 if (x != null)
1304 return x;
1305 }
1306 if ((sym.flags() & INTERFACE) != 0) {
1307 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
1308 Type x = asSuper(l.head, sym);
1309 if (x != null)
1310 return x;
1311 }
1312 }
1313 return null;
1314 }
1316 @Override
1317 public Type visitArrayType(ArrayType t, Symbol sym) {
1318 return isSubtype(t, sym.type) ? sym.type : null;
1319 }
1321 @Override
1322 public Type visitTypeVar(TypeVar t, Symbol sym) {
1323 if (t.tsym == sym)
1324 return t;
1325 else
1326 return asSuper(t.bound, sym);
1327 }
1329 @Override
1330 public Type visitErrorType(ErrorType t, Symbol sym) {
1331 return t;
1332 }
1333 };
1335 /**
1336 * Return the base type of t or any of its outer types that starts
1337 * with the given symbol. If none exists, return null.
1338 *
1339 * @param t a type
1340 * @param sym a symbol
1341 */
1342 public Type asOuterSuper(Type t, Symbol sym) {
1343 switch (t.tag) {
1344 case CLASS:
1345 do {
1346 Type s = asSuper(t, sym);
1347 if (s != null) return s;
1348 t = t.getEnclosingType();
1349 } while (t.tag == CLASS);
1350 return null;
1351 case ARRAY:
1352 return isSubtype(t, sym.type) ? sym.type : null;
1353 case TYPEVAR:
1354 return asSuper(t, sym);
1355 case ERROR:
1356 return t;
1357 default:
1358 return null;
1359 }
1360 }
1362 /**
1363 * Return the base type of t or any of its enclosing types that
1364 * starts with the given symbol. If none exists, return null.
1365 *
1366 * @param t a type
1367 * @param sym a symbol
1368 */
1369 public Type asEnclosingSuper(Type t, Symbol sym) {
1370 switch (t.tag) {
1371 case CLASS:
1372 do {
1373 Type s = asSuper(t, sym);
1374 if (s != null) return s;
1375 Type outer = t.getEnclosingType();
1376 t = (outer.tag == CLASS) ? outer :
1377 (t.tsym.owner.enclClass() != null) ? t.tsym.owner.enclClass().type :
1378 Type.noType;
1379 } while (t.tag == CLASS);
1380 return null;
1381 case ARRAY:
1382 return isSubtype(t, sym.type) ? sym.type : null;
1383 case TYPEVAR:
1384 return asSuper(t, sym);
1385 case ERROR:
1386 return t;
1387 default:
1388 return null;
1389 }
1390 }
1391 // </editor-fold>
1393 // <editor-fold defaultstate="collapsed" desc="memberType">
1394 /**
1395 * The type of given symbol, seen as a member of t.
1396 *
1397 * @param t a type
1398 * @param sym a symbol
1399 */
1400 public Type memberType(Type t, Symbol sym) {
1401 return (sym.flags() & STATIC) != 0
1402 ? sym.type
1403 : memberType.visit(t, sym);
1404 }
1405 // where
1406 private SimpleVisitor<Type,Symbol> memberType = new SimpleVisitor<Type,Symbol>() {
1408 public Type visitType(Type t, Symbol sym) {
1409 return sym.type;
1410 }
1412 @Override
1413 public Type visitWildcardType(WildcardType t, Symbol sym) {
1414 return memberType(upperBound(t), sym);
1415 }
1417 @Override
1418 public Type visitClassType(ClassType t, Symbol sym) {
1419 Symbol owner = sym.owner;
1420 long flags = sym.flags();
1421 if (((flags & STATIC) == 0) && owner.type.isParameterized()) {
1422 Type base = asOuterSuper(t, owner);
1423 if (base != null) {
1424 List<Type> ownerParams = owner.type.allparams();
1425 List<Type> baseParams = base.allparams();
1426 if (ownerParams.nonEmpty()) {
1427 if (baseParams.isEmpty()) {
1428 // then base is a raw type
1429 return erasure(sym.type);
1430 } else {
1431 return subst(sym.type, ownerParams, baseParams);
1432 }
1433 }
1434 }
1435 }
1436 return sym.type;
1437 }
1439 @Override
1440 public Type visitTypeVar(TypeVar t, Symbol sym) {
1441 return memberType(t.bound, sym);
1442 }
1444 @Override
1445 public Type visitErrorType(ErrorType t, Symbol sym) {
1446 return t;
1447 }
1448 };
1449 // </editor-fold>
1451 // <editor-fold defaultstate="collapsed" desc="isAssignable">
1452 public boolean isAssignable(Type t, Type s) {
1453 return isAssignable(t, s, Warner.noWarnings);
1454 }
1456 /**
1457 * Is t assignable to s?<br>
1458 * Equivalent to subtype except for constant values and raw
1459 * types.<br>
1460 * (not defined for Method and ForAll types)
1461 */
1462 public boolean isAssignable(Type t, Type s, Warner warn) {
1463 if (t.tag == ERROR)
1464 return true;
1465 if (t.tag <= INT && t.constValue() != null) {
1466 int value = ((Number)t.constValue()).intValue();
1467 switch (s.tag) {
1468 case BYTE:
1469 if (Byte.MIN_VALUE <= value && value <= Byte.MAX_VALUE)
1470 return true;
1471 break;
1472 case CHAR:
1473 if (Character.MIN_VALUE <= value && value <= Character.MAX_VALUE)
1474 return true;
1475 break;
1476 case SHORT:
1477 if (Short.MIN_VALUE <= value && value <= Short.MAX_VALUE)
1478 return true;
1479 break;
1480 case INT:
1481 return true;
1482 case CLASS:
1483 switch (unboxedType(s).tag) {
1484 case BYTE:
1485 case CHAR:
1486 case SHORT:
1487 return isAssignable(t, unboxedType(s), warn);
1488 }
1489 break;
1490 }
1491 }
1492 return isConvertible(t, s, warn);
1493 }
1494 // </editor-fold>
1496 // <editor-fold defaultstate="collapsed" desc="erasure">
1497 /**
1498 * The erasure of t {@code |t|} -- the type that results when all
1499 * type parameters in t are deleted.
1500 */
1501 public Type erasure(Type t) {
1502 if (t.tag <= lastBaseTag)
1503 return t; /* fast special case */
1504 else
1505 return erasure.visit(t);
1506 }
1507 // where
1508 private UnaryVisitor<Type> erasure = new UnaryVisitor<Type>() {
1509 public Type visitType(Type t, Void ignored) {
1510 if (t.tag <= lastBaseTag)
1511 return t; /*fast special case*/
1512 else
1513 return t.map(erasureFun);
1514 }
1516 @Override
1517 public Type visitWildcardType(WildcardType t, Void ignored) {
1518 return erasure(upperBound(t));
1519 }
1521 @Override
1522 public Type visitClassType(ClassType t, Void ignored) {
1523 return t.tsym.erasure(Types.this);
1524 }
1526 @Override
1527 public Type visitTypeVar(TypeVar t, Void ignored) {
1528 return erasure(t.bound);
1529 }
1531 @Override
1532 public Type visitErrorType(ErrorType t, Void ignored) {
1533 return t;
1534 }
1535 };
1536 private Mapping erasureFun = new Mapping ("erasure") {
1537 public Type apply(Type t) { return erasure(t); }
1538 };
1540 public List<Type> erasure(List<Type> ts) {
1541 return Type.map(ts, erasureFun);
1542 }
1543 // </editor-fold>
1545 // <editor-fold defaultstate="collapsed" desc="makeCompoundType">
1546 /**
1547 * Make a compound type from non-empty list of types
1548 *
1549 * @param bounds the types from which the compound type is formed
1550 * @param supertype is objectType if all bounds are interfaces,
1551 * null otherwise.
1552 */
1553 public Type makeCompoundType(List<Type> bounds,
1554 Type supertype) {
1555 ClassSymbol bc =
1556 new ClassSymbol(ABSTRACT|PUBLIC|SYNTHETIC|COMPOUND|ACYCLIC,
1557 Type.moreInfo
1558 ? names.fromString(bounds.toString())
1559 : names.empty,
1560 syms.noSymbol);
1561 if (bounds.head.tag == TYPEVAR)
1562 // error condition, recover
1563 bc.erasure_field = syms.objectType;
1564 else
1565 bc.erasure_field = erasure(bounds.head);
1566 bc.members_field = new Scope(bc);
1567 ClassType bt = (ClassType)bc.type;
1568 bt.allparams_field = List.nil();
1569 if (supertype != null) {
1570 bt.supertype_field = supertype;
1571 bt.interfaces_field = bounds;
1572 } else {
1573 bt.supertype_field = bounds.head;
1574 bt.interfaces_field = bounds.tail;
1575 }
1576 assert bt.supertype_field.tsym.completer != null
1577 || !bt.supertype_field.isInterface()
1578 : bt.supertype_field;
1579 return bt;
1580 }
1582 /**
1583 * Same as {@link #makeCompoundType(List,Type)}, except that the
1584 * second parameter is computed directly. Note that this might
1585 * cause a symbol completion. Hence, this version of
1586 * makeCompoundType may not be called during a classfile read.
1587 */
1588 public Type makeCompoundType(List<Type> bounds) {
1589 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1590 supertype(bounds.head) : null;
1591 return makeCompoundType(bounds, supertype);
1592 }
1594 /**
1595 * A convenience wrapper for {@link #makeCompoundType(List)}; the
1596 * arguments are converted to a list and passed to the other
1597 * method. Note that this might cause a symbol completion.
1598 * Hence, this version of makeCompoundType may not be called
1599 * during a classfile read.
1600 */
1601 public Type makeCompoundType(Type bound1, Type bound2) {
1602 return makeCompoundType(List.of(bound1, bound2));
1603 }
1604 // </editor-fold>
1606 // <editor-fold defaultstate="collapsed" desc="supertype">
1607 public Type supertype(Type t) {
1608 return supertype.visit(t);
1609 }
1610 // where
1611 private UnaryVisitor<Type> supertype = new UnaryVisitor<Type>() {
1613 public Type visitType(Type t, Void ignored) {
1614 // A note on wildcards: there is no good way to
1615 // determine a supertype for a super bounded wildcard.
1616 return null;
1617 }
1619 @Override
1620 public Type visitClassType(ClassType t, Void ignored) {
1621 if (t.supertype_field == null) {
1622 Type supertype = ((ClassSymbol)t.tsym).getSuperclass();
1623 // An interface has no superclass; its supertype is Object.
1624 if (t.isInterface())
1625 supertype = ((ClassType)t.tsym.type).supertype_field;
1626 if (t.supertype_field == null) {
1627 List<Type> actuals = classBound(t).allparams();
1628 List<Type> formals = t.tsym.type.allparams();
1629 if (actuals.isEmpty()) {
1630 if (formals.isEmpty())
1631 // Should not happen. See comments below in interfaces
1632 t.supertype_field = supertype;
1633 else
1634 t.supertype_field = erasure(supertype);
1635 } else {
1636 t.supertype_field = subst(supertype, formals, actuals);
1637 }
1638 }
1639 }
1640 return t.supertype_field;
1641 }
1643 /**
1644 * The supertype is always a class type. If the type
1645 * variable's bounds start with a class type, this is also
1646 * the supertype. Otherwise, the supertype is
1647 * java.lang.Object.
1648 */
1649 @Override
1650 public Type visitTypeVar(TypeVar t, Void ignored) {
1651 if (t.bound.tag == TYPEVAR ||
1652 (!t.bound.isCompound() && !t.bound.isInterface())) {
1653 return t.bound;
1654 } else {
1655 return supertype(t.bound);
1656 }
1657 }
1659 @Override
1660 public Type visitArrayType(ArrayType t, Void ignored) {
1661 if (t.elemtype.isPrimitive() || isSameType(t.elemtype, syms.objectType))
1662 return arraySuperType();
1663 else
1664 return new ArrayType(supertype(t.elemtype), t.tsym);
1665 }
1667 @Override
1668 public Type visitErrorType(ErrorType t, Void ignored) {
1669 return t;
1670 }
1671 };
1672 // </editor-fold>
1674 // <editor-fold defaultstate="collapsed" desc="interfaces">
1675 /**
1676 * Return the interfaces implemented by this class.
1677 */
1678 public List<Type> interfaces(Type t) {
1679 return interfaces.visit(t);
1680 }
1681 // where
1682 private UnaryVisitor<List<Type>> interfaces = new UnaryVisitor<List<Type>>() {
1684 public List<Type> visitType(Type t, Void ignored) {
1685 return List.nil();
1686 }
1688 @Override
1689 public List<Type> visitClassType(ClassType t, Void ignored) {
1690 if (t.interfaces_field == null) {
1691 List<Type> interfaces = ((ClassSymbol)t.tsym).getInterfaces();
1692 if (t.interfaces_field == null) {
1693 // If t.interfaces_field is null, then t must
1694 // be a parameterized type (not to be confused
1695 // with a generic type declaration).
1696 // Terminology:
1697 // Parameterized type: List<String>
1698 // Generic type declaration: class List<E> { ... }
1699 // So t corresponds to List<String> and
1700 // t.tsym.type corresponds to List<E>.
1701 // The reason t must be parameterized type is
1702 // that completion will happen as a side
1703 // effect of calling
1704 // ClassSymbol.getInterfaces. Since
1705 // t.interfaces_field is null after
1706 // completion, we can assume that t is not the
1707 // type of a class/interface declaration.
1708 assert t != t.tsym.type : t.toString();
1709 List<Type> actuals = t.allparams();
1710 List<Type> formals = t.tsym.type.allparams();
1711 if (actuals.isEmpty()) {
1712 if (formals.isEmpty()) {
1713 // In this case t is not generic (nor raw).
1714 // So this should not happen.
1715 t.interfaces_field = interfaces;
1716 } else {
1717 t.interfaces_field = erasure(interfaces);
1718 }
1719 } else {
1720 t.interfaces_field =
1721 upperBounds(subst(interfaces, formals, actuals));
1722 }
1723 }
1724 }
1725 return t.interfaces_field;
1726 }
1728 @Override
1729 public List<Type> visitTypeVar(TypeVar t, Void ignored) {
1730 if (t.bound.isCompound())
1731 return interfaces(t.bound);
1733 if (t.bound.isInterface())
1734 return List.of(t.bound);
1736 return List.nil();
1737 }
1738 };
1739 // </editor-fold>
1741 // <editor-fold defaultstate="collapsed" desc="isDerivedRaw">
1742 Map<Type,Boolean> isDerivedRawCache = new HashMap<Type,Boolean>();
1744 public boolean isDerivedRaw(Type t) {
1745 Boolean result = isDerivedRawCache.get(t);
1746 if (result == null) {
1747 result = isDerivedRawInternal(t);
1748 isDerivedRawCache.put(t, result);
1749 }
1750 return result;
1751 }
1753 public boolean isDerivedRawInternal(Type t) {
1754 if (t.isErroneous())
1755 return false;
1756 return
1757 t.isRaw() ||
1758 supertype(t) != null && isDerivedRaw(supertype(t)) ||
1759 isDerivedRaw(interfaces(t));
1760 }
1762 public boolean isDerivedRaw(List<Type> ts) {
1763 List<Type> l = ts;
1764 while (l.nonEmpty() && !isDerivedRaw(l.head)) l = l.tail;
1765 return l.nonEmpty();
1766 }
1767 // </editor-fold>
1769 // <editor-fold defaultstate="collapsed" desc="setBounds">
1770 /**
1771 * Set the bounds field of the given type variable to reflect a
1772 * (possibly multiple) list of bounds.
1773 * @param t a type variable
1774 * @param bounds the bounds, must be nonempty
1775 * @param supertype is objectType if all bounds are interfaces,
1776 * null otherwise.
1777 */
1778 public void setBounds(TypeVar t, List<Type> bounds, Type supertype) {
1779 if (bounds.tail.isEmpty())
1780 t.bound = bounds.head;
1781 else
1782 t.bound = makeCompoundType(bounds, supertype);
1783 t.rank_field = -1;
1784 }
1786 /**
1787 * Same as {@link #setBounds(Type.TypeVar,List,Type)}, except that
1788 * third parameter is computed directly. Note that this test
1789 * might cause a symbol completion. Hence, this version of
1790 * setBounds may not be called during a classfile read.
1791 */
1792 public void setBounds(TypeVar t, List<Type> bounds) {
1793 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1794 supertype(bounds.head) : null;
1795 setBounds(t, bounds, supertype);
1796 t.rank_field = -1;
1797 }
1798 // </editor-fold>
1800 // <editor-fold defaultstate="collapsed" desc="getBounds">
1801 /**
1802 * Return list of bounds of the given type variable.
1803 */
1804 public List<Type> getBounds(TypeVar t) {
1805 if (t.bound.isErroneous() || !t.bound.isCompound())
1806 return List.of(t.bound);
1807 else if ((erasure(t).tsym.flags() & INTERFACE) == 0)
1808 return interfaces(t).prepend(supertype(t));
1809 else
1810 // No superclass was given in bounds.
1811 // In this case, supertype is Object, erasure is first interface.
1812 return interfaces(t);
1813 }
1814 // </editor-fold>
1816 // <editor-fold defaultstate="collapsed" desc="classBound">
1817 /**
1818 * If the given type is a (possibly selected) type variable,
1819 * return the bounding class of this type, otherwise return the
1820 * type itself.
1821 */
1822 public Type classBound(Type t) {
1823 return classBound.visit(t);
1824 }
1825 // where
1826 private UnaryVisitor<Type> classBound = new UnaryVisitor<Type>() {
1828 public Type visitType(Type t, Void ignored) {
1829 return t;
1830 }
1832 @Override
1833 public Type visitClassType(ClassType t, Void ignored) {
1834 Type outer1 = classBound(t.getEnclosingType());
1835 if (outer1 != t.getEnclosingType())
1836 return new ClassType(outer1, t.getTypeArguments(), t.tsym);
1837 else
1838 return t;
1839 }
1841 @Override
1842 public Type visitTypeVar(TypeVar t, Void ignored) {
1843 return classBound(supertype(t));
1844 }
1846 @Override
1847 public Type visitErrorType(ErrorType t, Void ignored) {
1848 return t;
1849 }
1850 };
1851 // </editor-fold>
1853 // <editor-fold defaultstate="collapsed" desc="sub signature / override equivalence">
1854 /**
1855 * Returns true iff the first signature is a <em>sub
1856 * signature</em> of the other. This is <b>not</b> an equivalence
1857 * relation.
1858 *
1859 * @see "The Java Language Specification, Third Ed. (8.4.2)."
1860 * @see #overrideEquivalent(Type t, Type s)
1861 * @param t first signature (possibly raw).
1862 * @param s second signature (could be subjected to erasure).
1863 * @return true if t is a sub signature of s.
1864 */
1865 public boolean isSubSignature(Type t, Type s) {
1866 return hasSameArgs(t, s) || hasSameArgs(t, erasure(s));
1867 }
1869 /**
1870 * Returns true iff these signatures are related by <em>override
1871 * equivalence</em>. This is the natural extension of
1872 * isSubSignature to an equivalence relation.
1873 *
1874 * @see "The Java Language Specification, Third Ed. (8.4.2)."
1875 * @see #isSubSignature(Type t, Type s)
1876 * @param t a signature (possible raw, could be subjected to
1877 * erasure).
1878 * @param s a signature (possible raw, could be subjected to
1879 * erasure).
1880 * @return true if either argument is a sub signature of the other.
1881 */
1882 public boolean overrideEquivalent(Type t, Type s) {
1883 return hasSameArgs(t, s) ||
1884 hasSameArgs(t, erasure(s)) || hasSameArgs(erasure(t), s);
1885 }
1887 /**
1888 * Does t have the same arguments as s? It is assumed that both
1889 * types are (possibly polymorphic) method types. Monomorphic
1890 * method types "have the same arguments", if their argument lists
1891 * are equal. Polymorphic method types "have the same arguments",
1892 * if they have the same arguments after renaming all type
1893 * variables of one to corresponding type variables in the other,
1894 * where correspondence is by position in the type parameter list.
1895 */
1896 public boolean hasSameArgs(Type t, Type s) {
1897 return hasSameArgs.visit(t, s);
1898 }
1899 // where
1900 private TypeRelation hasSameArgs = new TypeRelation() {
1902 public Boolean visitType(Type t, Type s) {
1903 throw new AssertionError();
1904 }
1906 @Override
1907 public Boolean visitMethodType(MethodType t, Type s) {
1908 return s.tag == METHOD
1909 && containsTypeEquivalent(t.argtypes, s.getParameterTypes());
1910 }
1912 @Override
1913 public Boolean visitForAll(ForAll t, Type s) {
1914 if (s.tag != FORALL)
1915 return false;
1917 ForAll forAll = (ForAll)s;
1918 return hasSameBounds(t, forAll)
1919 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
1920 }
1922 @Override
1923 public Boolean visitErrorType(ErrorType t, Type s) {
1924 return false;
1925 }
1926 };
1927 // </editor-fold>
1929 // <editor-fold defaultstate="collapsed" desc="subst">
1930 public List<Type> subst(List<Type> ts,
1931 List<Type> from,
1932 List<Type> to) {
1933 return new Subst(from, to).subst(ts);
1934 }
1936 /**
1937 * Substitute all occurrences of a type in `from' with the
1938 * corresponding type in `to' in 't'. Match lists `from' and `to'
1939 * from the right: If lists have different length, discard leading
1940 * elements of the longer list.
1941 */
1942 public Type subst(Type t, List<Type> from, List<Type> to) {
1943 return new Subst(from, to).subst(t);
1944 }
1946 private class Subst extends UnaryVisitor<Type> {
1947 List<Type> from;
1948 List<Type> to;
1950 public Subst(List<Type> from, List<Type> to) {
1951 int fromLength = from.length();
1952 int toLength = to.length();
1953 while (fromLength > toLength) {
1954 fromLength--;
1955 from = from.tail;
1956 }
1957 while (fromLength < toLength) {
1958 toLength--;
1959 to = to.tail;
1960 }
1961 this.from = from;
1962 this.to = to;
1963 }
1965 Type subst(Type t) {
1966 if (from.tail == null)
1967 return t;
1968 else
1969 return visit(t);
1970 }
1972 List<Type> subst(List<Type> ts) {
1973 if (from.tail == null)
1974 return ts;
1975 boolean wild = false;
1976 if (ts.nonEmpty() && from.nonEmpty()) {
1977 Type head1 = subst(ts.head);
1978 List<Type> tail1 = subst(ts.tail);
1979 if (head1 != ts.head || tail1 != ts.tail)
1980 return tail1.prepend(head1);
1981 }
1982 return ts;
1983 }
1985 public Type visitType(Type t, Void ignored) {
1986 return t;
1987 }
1989 @Override
1990 public Type visitMethodType(MethodType t, Void ignored) {
1991 List<Type> argtypes = subst(t.argtypes);
1992 Type restype = subst(t.restype);
1993 List<Type> thrown = subst(t.thrown);
1994 if (argtypes == t.argtypes &&
1995 restype == t.restype &&
1996 thrown == t.thrown)
1997 return t;
1998 else
1999 return new MethodType(argtypes, restype, thrown, t.tsym);
2000 }
2002 @Override
2003 public Type visitTypeVar(TypeVar t, Void ignored) {
2004 for (List<Type> from = this.from, to = this.to;
2005 from.nonEmpty();
2006 from = from.tail, to = to.tail) {
2007 if (t == from.head) {
2008 return to.head.withTypeVar(t);
2009 }
2010 }
2011 return t;
2012 }
2014 @Override
2015 public Type visitClassType(ClassType t, Void ignored) {
2016 if (!t.isCompound()) {
2017 List<Type> typarams = t.getTypeArguments();
2018 List<Type> typarams1 = subst(typarams);
2019 Type outer = t.getEnclosingType();
2020 Type outer1 = subst(outer);
2021 if (typarams1 == typarams && outer1 == outer)
2022 return t;
2023 else
2024 return new ClassType(outer1, typarams1, t.tsym);
2025 } else {
2026 Type st = subst(supertype(t));
2027 List<Type> is = upperBounds(subst(interfaces(t)));
2028 if (st == supertype(t) && is == interfaces(t))
2029 return t;
2030 else
2031 return makeCompoundType(is.prepend(st));
2032 }
2033 }
2035 @Override
2036 public Type visitWildcardType(WildcardType t, Void ignored) {
2037 Type bound = t.type;
2038 if (t.kind != BoundKind.UNBOUND)
2039 bound = subst(bound);
2040 if (bound == t.type) {
2041 return t;
2042 } else {
2043 if (t.isExtendsBound() && bound.isExtendsBound())
2044 bound = upperBound(bound);
2045 return new WildcardType(bound, t.kind, syms.boundClass, t.bound);
2046 }
2047 }
2049 @Override
2050 public Type visitArrayType(ArrayType t, Void ignored) {
2051 Type elemtype = subst(t.elemtype);
2052 if (elemtype == t.elemtype)
2053 return t;
2054 else
2055 return new ArrayType(upperBound(elemtype), t.tsym);
2056 }
2058 @Override
2059 public Type visitForAll(ForAll t, Void ignored) {
2060 List<Type> tvars1 = substBounds(t.tvars, from, to);
2061 Type qtype1 = subst(t.qtype);
2062 if (tvars1 == t.tvars && qtype1 == t.qtype) {
2063 return t;
2064 } else if (tvars1 == t.tvars) {
2065 return new ForAll(tvars1, qtype1);
2066 } else {
2067 return new ForAll(tvars1, Types.this.subst(qtype1, t.tvars, tvars1));
2068 }
2069 }
2071 @Override
2072 public Type visitErrorType(ErrorType t, Void ignored) {
2073 return t;
2074 }
2075 }
2077 public List<Type> substBounds(List<Type> tvars,
2078 List<Type> from,
2079 List<Type> to) {
2080 if (tvars.isEmpty())
2081 return tvars;
2082 if (tvars.tail.isEmpty())
2083 // fast common case
2084 return List.<Type>of(substBound((TypeVar)tvars.head, from, to));
2085 ListBuffer<Type> newBoundsBuf = lb();
2086 boolean changed = false;
2087 // calculate new bounds
2088 for (Type t : tvars) {
2089 TypeVar tv = (TypeVar) t;
2090 Type bound = subst(tv.bound, from, to);
2091 if (bound != tv.bound)
2092 changed = true;
2093 newBoundsBuf.append(bound);
2094 }
2095 if (!changed)
2096 return tvars;
2097 ListBuffer<Type> newTvars = lb();
2098 // create new type variables without bounds
2099 for (Type t : tvars) {
2100 newTvars.append(new TypeVar(t.tsym, null, syms.botType));
2101 }
2102 // the new bounds should use the new type variables in place
2103 // of the old
2104 List<Type> newBounds = newBoundsBuf.toList();
2105 from = tvars;
2106 to = newTvars.toList();
2107 for (; !newBounds.isEmpty(); newBounds = newBounds.tail) {
2108 newBounds.head = subst(newBounds.head, from, to);
2109 }
2110 newBounds = newBoundsBuf.toList();
2111 // set the bounds of new type variables to the new bounds
2112 for (Type t : newTvars.toList()) {
2113 TypeVar tv = (TypeVar) t;
2114 tv.bound = newBounds.head;
2115 newBounds = newBounds.tail;
2116 }
2117 return newTvars.toList();
2118 }
2120 public TypeVar substBound(TypeVar t, List<Type> from, List<Type> to) {
2121 Type bound1 = subst(t.bound, from, to);
2122 if (bound1 == t.bound)
2123 return t;
2124 else
2125 return new TypeVar(t.tsym, bound1, syms.botType);
2126 }
2127 // </editor-fold>
2129 // <editor-fold defaultstate="collapsed" desc="hasSameBounds">
2130 /**
2131 * Does t have the same bounds for quantified variables as s?
2132 */
2133 boolean hasSameBounds(ForAll t, ForAll s) {
2134 List<Type> l1 = t.tvars;
2135 List<Type> l2 = s.tvars;
2136 while (l1.nonEmpty() && l2.nonEmpty() &&
2137 isSameType(l1.head.getUpperBound(),
2138 subst(l2.head.getUpperBound(),
2139 s.tvars,
2140 t.tvars))) {
2141 l1 = l1.tail;
2142 l2 = l2.tail;
2143 }
2144 return l1.isEmpty() && l2.isEmpty();
2145 }
2146 // </editor-fold>
2148 // <editor-fold defaultstate="collapsed" desc="newInstances">
2149 /** Create new vector of type variables from list of variables
2150 * changing all recursive bounds from old to new list.
2151 */
2152 public List<Type> newInstances(List<Type> tvars) {
2153 List<Type> tvars1 = Type.map(tvars, newInstanceFun);
2154 for (List<Type> l = tvars1; l.nonEmpty(); l = l.tail) {
2155 TypeVar tv = (TypeVar) l.head;
2156 tv.bound = subst(tv.bound, tvars, tvars1);
2157 }
2158 return tvars1;
2159 }
2160 static private Mapping newInstanceFun = new Mapping("newInstanceFun") {
2161 public Type apply(Type t) { return new TypeVar(t.tsym, t.getUpperBound(), t.getLowerBound()); }
2162 };
2163 // </editor-fold>
2165 // <editor-fold defaultstate="collapsed" desc="rank">
2166 /**
2167 * The rank of a class is the length of the longest path between
2168 * the class and java.lang.Object in the class inheritance
2169 * graph. Undefined for all but reference types.
2170 */
2171 public int rank(Type t) {
2172 switch(t.tag) {
2173 case CLASS: {
2174 ClassType cls = (ClassType)t;
2175 if (cls.rank_field < 0) {
2176 Name fullname = cls.tsym.getQualifiedName();
2177 if (fullname == fullname.table.java_lang_Object)
2178 cls.rank_field = 0;
2179 else {
2180 int r = rank(supertype(cls));
2181 for (List<Type> l = interfaces(cls);
2182 l.nonEmpty();
2183 l = l.tail) {
2184 if (rank(l.head) > r)
2185 r = rank(l.head);
2186 }
2187 cls.rank_field = r + 1;
2188 }
2189 }
2190 return cls.rank_field;
2191 }
2192 case TYPEVAR: {
2193 TypeVar tvar = (TypeVar)t;
2194 if (tvar.rank_field < 0) {
2195 int r = rank(supertype(tvar));
2196 for (List<Type> l = interfaces(tvar);
2197 l.nonEmpty();
2198 l = l.tail) {
2199 if (rank(l.head) > r) r = rank(l.head);
2200 }
2201 tvar.rank_field = r + 1;
2202 }
2203 return tvar.rank_field;
2204 }
2205 case ERROR:
2206 return 0;
2207 default:
2208 throw new AssertionError();
2209 }
2210 }
2211 // </editor-fold>
2213 // <editor-fold defaultstate="collapsed" desc="toString">
2214 /**
2215 * This toString is slightly more descriptive than the one on Type.
2216 */
2217 public String toString(Type t) {
2218 if (t.tag == FORALL) {
2219 ForAll forAll = (ForAll)t;
2220 return typaramsString(forAll.tvars) + forAll.qtype;
2221 }
2222 return "" + t;
2223 }
2224 // where
2225 private String typaramsString(List<Type> tvars) {
2226 StringBuffer s = new StringBuffer();
2227 s.append('<');
2228 boolean first = true;
2229 for (Type t : tvars) {
2230 if (!first) s.append(", ");
2231 first = false;
2232 appendTyparamString(((TypeVar)t), s);
2233 }
2234 s.append('>');
2235 return s.toString();
2236 }
2237 private void appendTyparamString(TypeVar t, StringBuffer buf) {
2238 buf.append(t);
2239 if (t.bound == null ||
2240 t.bound.tsym.getQualifiedName() == names.java_lang_Object)
2241 return;
2242 buf.append(" extends "); // Java syntax; no need for i18n
2243 Type bound = t.bound;
2244 if (!bound.isCompound()) {
2245 buf.append(bound);
2246 } else if ((erasure(t).tsym.flags() & INTERFACE) == 0) {
2247 buf.append(supertype(t));
2248 for (Type intf : interfaces(t)) {
2249 buf.append('&');
2250 buf.append(intf);
2251 }
2252 } else {
2253 // No superclass was given in bounds.
2254 // In this case, supertype is Object, erasure is first interface.
2255 boolean first = true;
2256 for (Type intf : interfaces(t)) {
2257 if (!first) buf.append('&');
2258 first = false;
2259 buf.append(intf);
2260 }
2261 }
2262 }
2263 // </editor-fold>
2265 // <editor-fold defaultstate="collapsed" desc="Determining least upper bounds of types">
2266 /**
2267 * A cache for closures.
2268 *
2269 * <p>A closure is a list of all the supertypes and interfaces of
2270 * a class or interface type, ordered by ClassSymbol.precedes
2271 * (that is, subclasses come first, arbitrary but fixed
2272 * otherwise).
2273 */
2274 private Map<Type,List<Type>> closureCache = new HashMap<Type,List<Type>>();
2276 /**
2277 * Returns the closure of a class or interface type.
2278 */
2279 public List<Type> closure(Type t) {
2280 List<Type> cl = closureCache.get(t);
2281 if (cl == null) {
2282 Type st = supertype(t);
2283 if (!t.isCompound()) {
2284 if (st.tag == CLASS) {
2285 cl = insert(closure(st), t);
2286 } else if (st.tag == TYPEVAR) {
2287 cl = closure(st).prepend(t);
2288 } else {
2289 cl = List.of(t);
2290 }
2291 } else {
2292 cl = closure(supertype(t));
2293 }
2294 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail)
2295 cl = union(cl, closure(l.head));
2296 closureCache.put(t, cl);
2297 }
2298 return cl;
2299 }
2301 /**
2302 * Insert a type in a closure
2303 */
2304 public List<Type> insert(List<Type> cl, Type t) {
2305 if (cl.isEmpty() || t.tsym.precedes(cl.head.tsym, this)) {
2306 return cl.prepend(t);
2307 } else if (cl.head.tsym.precedes(t.tsym, this)) {
2308 return insert(cl.tail, t).prepend(cl.head);
2309 } else {
2310 return cl;
2311 }
2312 }
2314 /**
2315 * Form the union of two closures
2316 */
2317 public List<Type> union(List<Type> cl1, List<Type> cl2) {
2318 if (cl1.isEmpty()) {
2319 return cl2;
2320 } else if (cl2.isEmpty()) {
2321 return cl1;
2322 } else if (cl1.head.tsym.precedes(cl2.head.tsym, this)) {
2323 return union(cl1.tail, cl2).prepend(cl1.head);
2324 } else if (cl2.head.tsym.precedes(cl1.head.tsym, this)) {
2325 return union(cl1, cl2.tail).prepend(cl2.head);
2326 } else {
2327 return union(cl1.tail, cl2.tail).prepend(cl1.head);
2328 }
2329 }
2331 /**
2332 * Intersect two closures
2333 */
2334 public List<Type> intersect(List<Type> cl1, List<Type> cl2) {
2335 if (cl1 == cl2)
2336 return cl1;
2337 if (cl1.isEmpty() || cl2.isEmpty())
2338 return List.nil();
2339 if (cl1.head.tsym.precedes(cl2.head.tsym, this))
2340 return intersect(cl1.tail, cl2);
2341 if (cl2.head.tsym.precedes(cl1.head.tsym, this))
2342 return intersect(cl1, cl2.tail);
2343 if (isSameType(cl1.head, cl2.head))
2344 return intersect(cl1.tail, cl2.tail).prepend(cl1.head);
2345 if (cl1.head.tsym == cl2.head.tsym &&
2346 cl1.head.tag == CLASS && cl2.head.tag == CLASS) {
2347 if (cl1.head.isParameterized() && cl2.head.isParameterized()) {
2348 Type merge = merge(cl1.head,cl2.head);
2349 return intersect(cl1.tail, cl2.tail).prepend(merge);
2350 }
2351 if (cl1.head.isRaw() || cl2.head.isRaw())
2352 return intersect(cl1.tail, cl2.tail).prepend(erasure(cl1.head));
2353 }
2354 return intersect(cl1.tail, cl2.tail);
2355 }
2356 // where
2357 class TypePair {
2358 final Type t1;
2359 final Type t2;
2360 TypePair(Type t1, Type t2) {
2361 this.t1 = t1;
2362 this.t2 = t2;
2363 }
2364 @Override
2365 public int hashCode() {
2366 return 127 * Types.this.hashCode(t1) + Types.this.hashCode(t2);
2367 }
2368 @Override
2369 public boolean equals(Object obj) {
2370 if (!(obj instanceof TypePair))
2371 return false;
2372 TypePair typePair = (TypePair)obj;
2373 return isSameType(t1, typePair.t1)
2374 && isSameType(t2, typePair.t2);
2375 }
2376 }
2377 Set<TypePair> mergeCache = new HashSet<TypePair>();
2378 private Type merge(Type c1, Type c2) {
2379 ClassType class1 = (ClassType) c1;
2380 List<Type> act1 = class1.getTypeArguments();
2381 ClassType class2 = (ClassType) c2;
2382 List<Type> act2 = class2.getTypeArguments();
2383 ListBuffer<Type> merged = new ListBuffer<Type>();
2384 List<Type> typarams = class1.tsym.type.getTypeArguments();
2386 while (act1.nonEmpty() && act2.nonEmpty() && typarams.nonEmpty()) {
2387 if (containsType(act1.head, act2.head)) {
2388 merged.append(act1.head);
2389 } else if (containsType(act2.head, act1.head)) {
2390 merged.append(act2.head);
2391 } else {
2392 TypePair pair = new TypePair(c1, c2);
2393 Type m;
2394 if (mergeCache.add(pair)) {
2395 m = new WildcardType(lub(upperBound(act1.head),
2396 upperBound(act2.head)),
2397 BoundKind.EXTENDS,
2398 syms.boundClass);
2399 mergeCache.remove(pair);
2400 } else {
2401 m = new WildcardType(syms.objectType,
2402 BoundKind.UNBOUND,
2403 syms.boundClass);
2404 }
2405 merged.append(m.withTypeVar(typarams.head));
2406 }
2407 act1 = act1.tail;
2408 act2 = act2.tail;
2409 typarams = typarams.tail;
2410 }
2411 assert(act1.isEmpty() && act2.isEmpty() && typarams.isEmpty());
2412 return new ClassType(class1.getEnclosingType(), merged.toList(), class1.tsym);
2413 }
2415 /**
2416 * Return the minimum type of a closure, a compound type if no
2417 * unique minimum exists.
2418 */
2419 private Type compoundMin(List<Type> cl) {
2420 if (cl.isEmpty()) return syms.objectType;
2421 List<Type> compound = closureMin(cl);
2422 if (compound.isEmpty())
2423 return null;
2424 else if (compound.tail.isEmpty())
2425 return compound.head;
2426 else
2427 return makeCompoundType(compound);
2428 }
2430 /**
2431 * Return the minimum types of a closure, suitable for computing
2432 * compoundMin or glb.
2433 */
2434 private List<Type> closureMin(List<Type> cl) {
2435 ListBuffer<Type> classes = lb();
2436 ListBuffer<Type> interfaces = lb();
2437 while (!cl.isEmpty()) {
2438 Type current = cl.head;
2439 if (current.isInterface())
2440 interfaces.append(current);
2441 else
2442 classes.append(current);
2443 ListBuffer<Type> candidates = lb();
2444 for (Type t : cl.tail) {
2445 if (!isSubtypeNoCapture(current, t))
2446 candidates.append(t);
2447 }
2448 cl = candidates.toList();
2449 }
2450 return classes.appendList(interfaces).toList();
2451 }
2453 /**
2454 * Return the least upper bound of pair of types. if the lub does
2455 * not exist return null.
2456 */
2457 public Type lub(Type t1, Type t2) {
2458 return lub(List.of(t1, t2));
2459 }
2461 /**
2462 * Return the least upper bound (lub) of set of types. If the lub
2463 * does not exist return the type of null (bottom).
2464 */
2465 public Type lub(List<Type> ts) {
2466 final int ARRAY_BOUND = 1;
2467 final int CLASS_BOUND = 2;
2468 int boundkind = 0;
2469 for (Type t : ts) {
2470 switch (t.tag) {
2471 case CLASS:
2472 boundkind |= CLASS_BOUND;
2473 break;
2474 case ARRAY:
2475 boundkind |= ARRAY_BOUND;
2476 break;
2477 case TYPEVAR:
2478 do {
2479 t = t.getUpperBound();
2480 } while (t.tag == TYPEVAR);
2481 if (t.tag == ARRAY) {
2482 boundkind |= ARRAY_BOUND;
2483 } else {
2484 boundkind |= CLASS_BOUND;
2485 }
2486 break;
2487 default:
2488 if (t.isPrimitive())
2489 return syms.errType;
2490 }
2491 }
2492 switch (boundkind) {
2493 case 0:
2494 return syms.botType;
2496 case ARRAY_BOUND:
2497 // calculate lub(A[], B[])
2498 List<Type> elements = Type.map(ts, elemTypeFun);
2499 for (Type t : elements) {
2500 if (t.isPrimitive()) {
2501 // if a primitive type is found, then return
2502 // arraySuperType unless all the types are the
2503 // same
2504 Type first = ts.head;
2505 for (Type s : ts.tail) {
2506 if (!isSameType(first, s)) {
2507 // lub(int[], B[]) is Cloneable & Serializable
2508 return arraySuperType();
2509 }
2510 }
2511 // all the array types are the same, return one
2512 // lub(int[], int[]) is int[]
2513 return first;
2514 }
2515 }
2516 // lub(A[], B[]) is lub(A, B)[]
2517 return new ArrayType(lub(elements), syms.arrayClass);
2519 case CLASS_BOUND:
2520 // calculate lub(A, B)
2521 while (ts.head.tag != CLASS && ts.head.tag != TYPEVAR)
2522 ts = ts.tail;
2523 assert !ts.isEmpty();
2524 List<Type> cl = closure(ts.head);
2525 for (Type t : ts.tail) {
2526 if (t.tag == CLASS || t.tag == TYPEVAR)
2527 cl = intersect(cl, closure(t));
2528 }
2529 return compoundMin(cl);
2531 default:
2532 // calculate lub(A, B[])
2533 List<Type> classes = List.of(arraySuperType());
2534 for (Type t : ts) {
2535 if (t.tag != ARRAY) // Filter out any arrays
2536 classes = classes.prepend(t);
2537 }
2538 // lub(A, B[]) is lub(A, arraySuperType)
2539 return lub(classes);
2540 }
2541 }
2542 // where
2543 private Type arraySuperType = null;
2544 private Type arraySuperType() {
2545 // initialized lazily to avoid problems during compiler startup
2546 if (arraySuperType == null) {
2547 synchronized (this) {
2548 if (arraySuperType == null) {
2549 // JLS 10.8: all arrays implement Cloneable and Serializable.
2550 arraySuperType = makeCompoundType(List.of(syms.serializableType,
2551 syms.cloneableType),
2552 syms.objectType);
2553 }
2554 }
2555 }
2556 return arraySuperType;
2557 }
2558 // </editor-fold>
2560 // <editor-fold defaultstate="collapsed" desc="Greatest lower bound">
2561 public Type glb(Type t, Type s) {
2562 if (s == null)
2563 return t;
2564 else if (isSubtypeNoCapture(t, s))
2565 return t;
2566 else if (isSubtypeNoCapture(s, t))
2567 return s;
2569 List<Type> closure = union(closure(t), closure(s));
2570 List<Type> bounds = closureMin(closure);
2572 if (bounds.isEmpty()) { // length == 0
2573 return syms.objectType;
2574 } else if (bounds.tail.isEmpty()) { // length == 1
2575 return bounds.head;
2576 } else { // length > 1
2577 int classCount = 0;
2578 for (Type bound : bounds)
2579 if (!bound.isInterface())
2580 classCount++;
2581 if (classCount > 1)
2582 return syms.errType;
2583 }
2584 return makeCompoundType(bounds);
2585 }
2586 // </editor-fold>
2588 // <editor-fold defaultstate="collapsed" desc="hashCode">
2589 /**
2590 * Compute a hash code on a type.
2591 */
2592 public static int hashCode(Type t) {
2593 return hashCode.visit(t);
2594 }
2595 // where
2596 private static final UnaryVisitor<Integer> hashCode = new UnaryVisitor<Integer>() {
2598 public Integer visitType(Type t, Void ignored) {
2599 return t.tag;
2600 }
2602 @Override
2603 public Integer visitClassType(ClassType t, Void ignored) {
2604 int result = visit(t.getEnclosingType());
2605 result *= 127;
2606 result += t.tsym.flatName().hashCode();
2607 for (Type s : t.getTypeArguments()) {
2608 result *= 127;
2609 result += visit(s);
2610 }
2611 return result;
2612 }
2614 @Override
2615 public Integer visitWildcardType(WildcardType t, Void ignored) {
2616 int result = t.kind.hashCode();
2617 if (t.type != null) {
2618 result *= 127;
2619 result += visit(t.type);
2620 }
2621 return result;
2622 }
2624 @Override
2625 public Integer visitArrayType(ArrayType t, Void ignored) {
2626 return visit(t.elemtype) + 12;
2627 }
2629 @Override
2630 public Integer visitTypeVar(TypeVar t, Void ignored) {
2631 return System.identityHashCode(t.tsym);
2632 }
2634 @Override
2635 public Integer visitUndetVar(UndetVar t, Void ignored) {
2636 return System.identityHashCode(t);
2637 }
2639 @Override
2640 public Integer visitErrorType(ErrorType t, Void ignored) {
2641 return 0;
2642 }
2643 };
2644 // </editor-fold>
2646 // <editor-fold defaultstate="collapsed" desc="Return-Type-Substitutable">
2647 /**
2648 * Does t have a result that is a subtype of the result type of s,
2649 * suitable for covariant returns? It is assumed that both types
2650 * are (possibly polymorphic) method types. Monomorphic method
2651 * types are handled in the obvious way. Polymorphic method types
2652 * require renaming all type variables of one to corresponding
2653 * type variables in the other, where correspondence is by
2654 * position in the type parameter list. */
2655 public boolean resultSubtype(Type t, Type s, Warner warner) {
2656 List<Type> tvars = t.getTypeArguments();
2657 List<Type> svars = s.getTypeArguments();
2658 Type tres = t.getReturnType();
2659 Type sres = subst(s.getReturnType(), svars, tvars);
2660 return covariantReturnType(tres, sres, warner);
2661 }
2663 /**
2664 * Return-Type-Substitutable.
2665 * @see <a href="http://java.sun.com/docs/books/jls/">The Java
2666 * Language Specification, Third Ed. (8.4.5)</a>
2667 */
2668 public boolean returnTypeSubstitutable(Type r1, Type r2) {
2669 if (hasSameArgs(r1, r2))
2670 return resultSubtype(r1, r2, Warner.noWarnings);
2671 else
2672 return covariantReturnType(r1.getReturnType(),
2673 erasure(r2.getReturnType()),
2674 Warner.noWarnings);
2675 }
2677 public boolean returnTypeSubstitutable(Type r1,
2678 Type r2, Type r2res,
2679 Warner warner) {
2680 if (isSameType(r1.getReturnType(), r2res))
2681 return true;
2682 if (r1.getReturnType().isPrimitive() || r2res.isPrimitive())
2683 return false;
2685 if (hasSameArgs(r1, r2))
2686 return covariantReturnType(r1.getReturnType(), r2res, warner);
2687 if (!source.allowCovariantReturns())
2688 return false;
2689 if (isSubtypeUnchecked(r1.getReturnType(), r2res, warner))
2690 return true;
2691 if (!isSubtype(r1.getReturnType(), erasure(r2res)))
2692 return false;
2693 warner.warnUnchecked();
2694 return true;
2695 }
2697 /**
2698 * Is t an appropriate return type in an overrider for a
2699 * method that returns s?
2700 */
2701 public boolean covariantReturnType(Type t, Type s, Warner warner) {
2702 return
2703 isSameType(t, s) ||
2704 source.allowCovariantReturns() &&
2705 !t.isPrimitive() &&
2706 !s.isPrimitive() &&
2707 isAssignable(t, s, warner);
2708 }
2709 // </editor-fold>
2711 // <editor-fold defaultstate="collapsed" desc="Box/unbox support">
2712 /**
2713 * Return the class that boxes the given primitive.
2714 */
2715 public ClassSymbol boxedClass(Type t) {
2716 return reader.enterClass(syms.boxedName[t.tag]);
2717 }
2719 /**
2720 * Return the primitive type corresponding to a boxed type.
2721 */
2722 public Type unboxedType(Type t) {
2723 if (allowBoxing) {
2724 for (int i=0; i<syms.boxedName.length; i++) {
2725 Name box = syms.boxedName[i];
2726 if (box != null &&
2727 asSuper(t, reader.enterClass(box)) != null)
2728 return syms.typeOfTag[i];
2729 }
2730 }
2731 return Type.noType;
2732 }
2733 // </editor-fold>
2735 // <editor-fold defaultstate="collapsed" desc="Capture conversion">
2736 /*
2737 * JLS 3rd Ed. 5.1.10 Capture Conversion:
2738 *
2739 * Let G name a generic type declaration with n formal type
2740 * parameters A1 ... An with corresponding bounds U1 ... Un. There
2741 * exists a capture conversion from G<T1 ... Tn> to G<S1 ... Sn>,
2742 * where, for 1 <= i <= n:
2743 *
2744 * + If Ti is a wildcard type argument (4.5.1) of the form ? then
2745 * Si is a fresh type variable whose upper bound is
2746 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is the null
2747 * type.
2748 *
2749 * + If Ti is a wildcard type argument of the form ? extends Bi,
2750 * then Si is a fresh type variable whose upper bound is
2751 * glb(Bi, Ui[A1 := S1, ..., An := Sn]) and whose lower bound is
2752 * the null type, where glb(V1,... ,Vm) is V1 & ... & Vm. It is
2753 * a compile-time error if for any two classes (not interfaces)
2754 * Vi and Vj,Vi is not a subclass of Vj or vice versa.
2755 *
2756 * + If Ti is a wildcard type argument of the form ? super Bi,
2757 * then Si is a fresh type variable whose upper bound is
2758 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is Bi.
2759 *
2760 * + Otherwise, Si = Ti.
2761 *
2762 * Capture conversion on any type other than a parameterized type
2763 * (4.5) acts as an identity conversion (5.1.1). Capture
2764 * conversions never require a special action at run time and
2765 * therefore never throw an exception at run time.
2766 *
2767 * Capture conversion is not applied recursively.
2768 */
2769 /**
2770 * Capture conversion as specified by JLS 3rd Ed.
2771 */
2772 public Type capture(Type t) {
2773 if (t.tag != CLASS)
2774 return t;
2775 ClassType cls = (ClassType)t;
2776 if (cls.isRaw() || !cls.isParameterized())
2777 return cls;
2779 ClassType G = (ClassType)cls.asElement().asType();
2780 List<Type> A = G.getTypeArguments();
2781 List<Type> T = cls.getTypeArguments();
2782 List<Type> S = freshTypeVariables(T);
2784 List<Type> currentA = A;
2785 List<Type> currentT = T;
2786 List<Type> currentS = S;
2787 boolean captured = false;
2788 while (!currentA.isEmpty() &&
2789 !currentT.isEmpty() &&
2790 !currentS.isEmpty()) {
2791 if (currentS.head != currentT.head) {
2792 captured = true;
2793 WildcardType Ti = (WildcardType)currentT.head;
2794 Type Ui = currentA.head.getUpperBound();
2795 CapturedType Si = (CapturedType)currentS.head;
2796 if (Ui == null)
2797 Ui = syms.objectType;
2798 switch (Ti.kind) {
2799 case UNBOUND:
2800 Si.bound = subst(Ui, A, S);
2801 Si.lower = syms.botType;
2802 break;
2803 case EXTENDS:
2804 Si.bound = glb(Ti.getExtendsBound(), subst(Ui, A, S));
2805 Si.lower = syms.botType;
2806 break;
2807 case SUPER:
2808 Si.bound = subst(Ui, A, S);
2809 Si.lower = Ti.getSuperBound();
2810 break;
2811 }
2812 if (Si.bound == Si.lower)
2813 currentS.head = Si.bound;
2814 }
2815 currentA = currentA.tail;
2816 currentT = currentT.tail;
2817 currentS = currentS.tail;
2818 }
2819 if (!currentA.isEmpty() || !currentT.isEmpty() || !currentS.isEmpty())
2820 return erasure(t); // some "rare" type involved
2822 if (captured)
2823 return new ClassType(cls.getEnclosingType(), S, cls.tsym);
2824 else
2825 return t;
2826 }
2827 // where
2828 private List<Type> freshTypeVariables(List<Type> types) {
2829 ListBuffer<Type> result = lb();
2830 for (Type t : types) {
2831 if (t.tag == WILDCARD) {
2832 Type bound = ((WildcardType)t).getExtendsBound();
2833 if (bound == null)
2834 bound = syms.objectType;
2835 result.append(new CapturedType(capturedName,
2836 syms.noSymbol,
2837 bound,
2838 syms.botType,
2839 (WildcardType)t));
2840 } else {
2841 result.append(t);
2842 }
2843 }
2844 return result.toList();
2845 }
2846 // </editor-fold>
2848 // <editor-fold defaultstate="collapsed" desc="Internal utility methods">
2849 private List<Type> upperBounds(List<Type> ss) {
2850 if (ss.isEmpty()) return ss;
2851 Type head = upperBound(ss.head);
2852 List<Type> tail = upperBounds(ss.tail);
2853 if (head != ss.head || tail != ss.tail)
2854 return tail.prepend(head);
2855 else
2856 return ss;
2857 }
2859 private boolean sideCast(Type from, Type to, Warner warn) {
2860 // We are casting from type $from$ to type $to$, which are
2861 // non-final unrelated types. This method
2862 // tries to reject a cast by transferring type parameters
2863 // from $to$ to $from$ by common superinterfaces.
2864 boolean reverse = false;
2865 Type target = to;
2866 if ((to.tsym.flags() & INTERFACE) == 0) {
2867 assert (from.tsym.flags() & INTERFACE) != 0;
2868 reverse = true;
2869 to = from;
2870 from = target;
2871 }
2872 List<Type> commonSupers = superClosure(to, erasure(from));
2873 boolean giveWarning = commonSupers.isEmpty();
2874 // The arguments to the supers could be unified here to
2875 // get a more accurate analysis
2876 while (commonSupers.nonEmpty()) {
2877 Type t1 = asSuper(from, commonSupers.head.tsym);
2878 Type t2 = commonSupers.head; // same as asSuper(to, commonSupers.head.tsym);
2879 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
2880 return false;
2881 giveWarning = giveWarning || (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2));
2882 commonSupers = commonSupers.tail;
2883 }
2884 if (giveWarning && !isReifiable(to))
2885 warn.warnUnchecked();
2886 if (!source.allowCovariantReturns())
2887 // reject if there is a common method signature with
2888 // incompatible return types.
2889 chk.checkCompatibleAbstracts(warn.pos(), from, to);
2890 return true;
2891 }
2893 private boolean sideCastFinal(Type from, Type to, Warner warn) {
2894 // We are casting from type $from$ to type $to$, which are
2895 // unrelated types one of which is final and the other of
2896 // which is an interface. This method
2897 // tries to reject a cast by transferring type parameters
2898 // from the final class to the interface.
2899 boolean reverse = false;
2900 Type target = to;
2901 if ((to.tsym.flags() & INTERFACE) == 0) {
2902 assert (from.tsym.flags() & INTERFACE) != 0;
2903 reverse = true;
2904 to = from;
2905 from = target;
2906 }
2907 assert (from.tsym.flags() & FINAL) != 0;
2908 Type t1 = asSuper(from, to.tsym);
2909 if (t1 == null) return false;
2910 Type t2 = to;
2911 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
2912 return false;
2913 if (!source.allowCovariantReturns())
2914 // reject if there is a common method signature with
2915 // incompatible return types.
2916 chk.checkCompatibleAbstracts(warn.pos(), from, to);
2917 if (!isReifiable(target) &&
2918 (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2)))
2919 warn.warnUnchecked();
2920 return true;
2921 }
2923 private boolean giveWarning(Type from, Type to) {
2924 // To and from are (possibly different) parameterizations
2925 // of the same class or interface
2926 return to.isParameterized() && !containsType(to.getTypeArguments(), from.getTypeArguments());
2927 }
2929 private List<Type> superClosure(Type t, Type s) {
2930 List<Type> cl = List.nil();
2931 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
2932 if (isSubtype(s, erasure(l.head))) {
2933 cl = insert(cl, l.head);
2934 } else {
2935 cl = union(cl, superClosure(l.head, s));
2936 }
2937 }
2938 return cl;
2939 }
2941 private boolean containsTypeEquivalent(Type t, Type s) {
2942 return
2943 isSameType(t, s) || // shortcut
2944 containsType(t, s) && containsType(s, t);
2945 }
2947 /**
2948 * Adapt a type by computing a substitution which maps a source
2949 * type to a target type.
2950 *
2951 * @param source the source type
2952 * @param target the target type
2953 * @param from the type variables of the computed substitution
2954 * @param to the types of the computed substitution.
2955 */
2956 public void adapt(Type source,
2957 Type target,
2958 ListBuffer<Type> from,
2959 ListBuffer<Type> to) throws AdaptFailure {
2960 Map<Symbol,Type> mapping = new HashMap<Symbol,Type>();
2961 adaptRecursive(source, target, from, to, mapping);
2962 List<Type> fromList = from.toList();
2963 List<Type> toList = to.toList();
2964 while (!fromList.isEmpty()) {
2965 Type val = mapping.get(fromList.head.tsym);
2966 if (toList.head != val)
2967 toList.head = val;
2968 fromList = fromList.tail;
2969 toList = toList.tail;
2970 }
2971 }
2972 // where
2973 private void adaptRecursive(Type source,
2974 Type target,
2975 ListBuffer<Type> from,
2976 ListBuffer<Type> to,
2977 Map<Symbol,Type> mapping) throws AdaptFailure {
2978 if (source.tag == TYPEVAR) {
2979 // Check to see if there is
2980 // already a mapping for $source$, in which case
2981 // the old mapping will be merged with the new
2982 Type val = mapping.get(source.tsym);
2983 if (val != null) {
2984 if (val.isSuperBound() && target.isSuperBound()) {
2985 val = isSubtype(lowerBound(val), lowerBound(target))
2986 ? target : val;
2987 } else if (val.isExtendsBound() && target.isExtendsBound()) {
2988 val = isSubtype(upperBound(val), upperBound(target))
2989 ? val : target;
2990 } else if (!isSameType(val, target)) {
2991 throw new AdaptFailure();
2992 }
2993 } else {
2994 val = target;
2995 from.append(source);
2996 to.append(target);
2997 }
2998 mapping.put(source.tsym, val);
2999 } else if (source.tag == target.tag) {
3000 switch (source.tag) {
3001 case CLASS:
3002 adapt(source.allparams(), target.allparams(),
3003 from, to, mapping);
3004 break;
3005 case ARRAY:
3006 adaptRecursive(elemtype(source), elemtype(target),
3007 from, to, mapping);
3008 break;
3009 case WILDCARD:
3010 if (source.isExtendsBound()) {
3011 adaptRecursive(upperBound(source), upperBound(target),
3012 from, to, mapping);
3013 } else if (source.isSuperBound()) {
3014 adaptRecursive(lowerBound(source), lowerBound(target),
3015 from, to, mapping);
3016 }
3017 break;
3018 }
3019 }
3020 }
3021 public static class AdaptFailure extends Exception {
3022 static final long serialVersionUID = -7490231548272701566L;
3023 }
3025 /**
3026 * Adapt a type by computing a substitution which maps a list of
3027 * source types to a list of target types.
3028 *
3029 * @param source the source type
3030 * @param target the target type
3031 * @param from the type variables of the computed substitution
3032 * @param to the types of the computed substitution.
3033 */
3034 private void adapt(List<Type> source,
3035 List<Type> target,
3036 ListBuffer<Type> from,
3037 ListBuffer<Type> to,
3038 Map<Symbol,Type> mapping) throws AdaptFailure {
3039 if (source.length() == target.length()) {
3040 while (source.nonEmpty()) {
3041 adaptRecursive(source.head, target.head, from, to, mapping);
3042 source = source.tail;
3043 target = target.tail;
3044 }
3045 }
3046 }
3048 private void adaptSelf(Type t,
3049 ListBuffer<Type> from,
3050 ListBuffer<Type> to) {
3051 try {
3052 //if (t.tsym.type != t)
3053 adapt(t.tsym.type, t, from, to);
3054 } catch (AdaptFailure ex) {
3055 // Adapt should never fail calculating a mapping from
3056 // t.tsym.type to t as there can be no merge problem.
3057 throw new AssertionError(ex);
3058 }
3059 }
3061 /**
3062 * Rewrite all type variables (universal quantifiers) in the given
3063 * type to wildcards (existential quantifiers). This is used to
3064 * determine if a cast is allowed. For example, if high is true
3065 * and {@code T <: Number}, then {@code List<T>} is rewritten to
3066 * {@code List<? extends Number>}. Since {@code List<Integer> <:
3067 * List<? extends Number>} a {@code List<T>} can be cast to {@code
3068 * List<Integer>} with a warning.
3069 * @param t a type
3070 * @param high if true return an upper bound; otherwise a lower
3071 * bound
3072 * @param rewriteTypeVars only rewrite captured wildcards if false;
3073 * otherwise rewrite all type variables
3074 * @return the type rewritten with wildcards (existential
3075 * quantifiers) only
3076 */
3077 private Type rewriteQuantifiers(Type t, boolean high, boolean rewriteTypeVars) {
3078 ListBuffer<Type> from = new ListBuffer<Type>();
3079 ListBuffer<Type> to = new ListBuffer<Type>();
3080 adaptSelf(t, from, to);
3081 ListBuffer<Type> rewritten = new ListBuffer<Type>();
3082 List<Type> formals = from.toList();
3083 boolean changed = false;
3084 for (Type arg : to.toList()) {
3085 Type bound;
3086 if (rewriteTypeVars && arg.tag == TYPEVAR) {
3087 TypeVar tv = (TypeVar)arg;
3088 bound = high ? tv.bound : syms.botType;
3089 } else {
3090 bound = high ? upperBound(arg) : lowerBound(arg);
3091 }
3092 Type newarg = bound;
3093 if (arg != bound) {
3094 changed = true;
3095 newarg = high ? makeExtendsWildcard(bound, (TypeVar)formals.head)
3096 : makeSuperWildcard(bound, (TypeVar)formals.head);
3097 }
3098 rewritten.append(newarg);
3099 formals = formals.tail;
3100 }
3101 if (changed)
3102 return subst(t.tsym.type, from.toList(), rewritten.toList());
3103 else
3104 return t;
3105 }
3107 /**
3108 * Create a wildcard with the given upper (extends) bound; create
3109 * an unbounded wildcard if bound is Object.
3110 *
3111 * @param bound the upper bound
3112 * @param formal the formal type parameter that will be
3113 * substituted by the wildcard
3114 */
3115 private WildcardType makeExtendsWildcard(Type bound, TypeVar formal) {
3116 if (bound == syms.objectType) {
3117 return new WildcardType(syms.objectType,
3118 BoundKind.UNBOUND,
3119 syms.boundClass,
3120 formal);
3121 } else {
3122 return new WildcardType(bound,
3123 BoundKind.EXTENDS,
3124 syms.boundClass,
3125 formal);
3126 }
3127 }
3129 /**
3130 * Create a wildcard with the given lower (super) bound; create an
3131 * unbounded wildcard if bound is bottom (type of {@code null}).
3132 *
3133 * @param bound the lower bound
3134 * @param formal the formal type parameter that will be
3135 * substituted by the wildcard
3136 */
3137 private WildcardType makeSuperWildcard(Type bound, TypeVar formal) {
3138 if (bound.tag == BOT) {
3139 return new WildcardType(syms.objectType,
3140 BoundKind.UNBOUND,
3141 syms.boundClass,
3142 formal);
3143 } else {
3144 return new WildcardType(bound,
3145 BoundKind.SUPER,
3146 syms.boundClass,
3147 formal);
3148 }
3149 }
3151 /**
3152 * A wrapper for a type that allows use in sets.
3153 */
3154 class SingletonType {
3155 final Type t;
3156 SingletonType(Type t) {
3157 this.t = t;
3158 }
3159 public int hashCode() {
3160 return Types.this.hashCode(t);
3161 }
3162 public boolean equals(Object obj) {
3163 return (obj instanceof SingletonType) &&
3164 isSameType(t, ((SingletonType)obj).t);
3165 }
3166 public String toString() {
3167 return t.toString();
3168 }
3169 }
3170 // </editor-fold>
3172 // <editor-fold defaultstate="collapsed" desc="Visitors">
3173 /**
3174 * A default visitor for types. All visitor methods except
3175 * visitType are implemented by delegating to visitType. Concrete
3176 * subclasses must provide an implementation of visitType and can
3177 * override other methods as needed.
3178 *
3179 * @param <R> the return type of the operation implemented by this
3180 * visitor; use Void if no return type is needed.
3181 * @param <S> the type of the second argument (the first being the
3182 * type itself) of the operation implemented by this visitor; use
3183 * Void if a second argument is not needed.
3184 */
3185 public static abstract class DefaultTypeVisitor<R,S> implements Type.Visitor<R,S> {
3186 final public R visit(Type t, S s) { return t.accept(this, s); }
3187 public R visitClassType(ClassType t, S s) { return visitType(t, s); }
3188 public R visitWildcardType(WildcardType t, S s) { return visitType(t, s); }
3189 public R visitArrayType(ArrayType t, S s) { return visitType(t, s); }
3190 public R visitMethodType(MethodType t, S s) { return visitType(t, s); }
3191 public R visitPackageType(PackageType t, S s) { return visitType(t, s); }
3192 public R visitTypeVar(TypeVar t, S s) { return visitType(t, s); }
3193 public R visitCapturedType(CapturedType t, S s) { return visitType(t, s); }
3194 public R visitForAll(ForAll t, S s) { return visitType(t, s); }
3195 public R visitUndetVar(UndetVar t, S s) { return visitType(t, s); }
3196 public R visitErrorType(ErrorType t, S s) { return visitType(t, s); }
3197 }
3199 /**
3200 * A <em>simple</em> visitor for types. This visitor is simple as
3201 * captured wildcards, for-all types (generic methods), and
3202 * undetermined type variables (part of inference) are hidden.
3203 * Captured wildcards are hidden by treating them as type
3204 * variables and the rest are hidden by visiting their qtypes.
3205 *
3206 * @param <R> the return type of the operation implemented by this
3207 * visitor; use Void if no return type is needed.
3208 * @param <S> the type of the second argument (the first being the
3209 * type itself) of the operation implemented by this visitor; use
3210 * Void if a second argument is not needed.
3211 */
3212 public static abstract class SimpleVisitor<R,S> extends DefaultTypeVisitor<R,S> {
3213 @Override
3214 public R visitCapturedType(CapturedType t, S s) {
3215 return visitTypeVar(t, s);
3216 }
3217 @Override
3218 public R visitForAll(ForAll t, S s) {
3219 return visit(t.qtype, s);
3220 }
3221 @Override
3222 public R visitUndetVar(UndetVar t, S s) {
3223 return visit(t.qtype, s);
3224 }
3225 }
3227 /**
3228 * A plain relation on types. That is a 2-ary function on the
3229 * form Type × Type → Boolean.
3230 * <!-- In plain text: Type x Type -> Boolean -->
3231 */
3232 public static abstract class TypeRelation extends SimpleVisitor<Boolean,Type> {}
3234 /**
3235 * A convenience visitor for implementing operations that only
3236 * require one argument (the type itself), that is, unary
3237 * operations.
3238 *
3239 * @param <R> the return type of the operation implemented by this
3240 * visitor; use Void if no return type is needed.
3241 */
3242 public static abstract class UnaryVisitor<R> extends SimpleVisitor<R,Void> {
3243 final public R visit(Type t) { return t.accept(this, null); }
3244 }
3246 /**
3247 * A visitor for implementing a mapping from types to types. The
3248 * default behavior of this class is to implement the identity
3249 * mapping (mapping a type to itself). This can be overridden in
3250 * subclasses.
3251 *
3252 * @param <S> the type of the second argument (the first being the
3253 * type itself) of this mapping; use Void if a second argument is
3254 * not needed.
3255 */
3256 public static class MapVisitor<S> extends DefaultTypeVisitor<Type,S> {
3257 final public Type visit(Type t) { return t.accept(this, null); }
3258 public Type visitType(Type t, S s) { return t; }
3259 }
3260 // </editor-fold>
3261 }
