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src/share/classes/com/sun/tools/javac/code/Types.java@eaf608c64fec
src/share/classes/com/sun/tools/javac/code/Types.java
Wed, 02 Jul 2008 12:56:02 -0700
- author
- xdono
- date
- Wed, 02 Jul 2008 12:56:02 -0700
- changeset 54
- eaf608c64fec
- parent 41
- 6e9a43815df7
- child 79
- 36df13bde238
- permissions
- -rw-r--r--
6719955: Update copyright year
Summary: Update copyright year for files that have been modified in 2008
Reviewed-by: ohair, tbell
1 /*
2 * Copyright 2003-2008 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 }
305 else if (t.tag == TYPEVAR) {
306 return isSubtypeUnchecked(t.getUpperBound(), s, warn);
307 }
308 else if (!s.isRaw()) {
309 Type t2 = asSuper(t, s.tsym);
310 if (t2 != null && t2.isRaw()) {
311 if (isReifiable(s))
312 warn.silentUnchecked();
313 else
314 warn.warnUnchecked();
315 return true;
316 }
317 }
318 return false;
319 }
321 /**
322 * Is t a subtype of s?<br>
323 * (not defined for Method and ForAll types)
324 */
325 final public boolean isSubtype(Type t, Type s) {
326 return isSubtype(t, s, true);
327 }
328 final public boolean isSubtypeNoCapture(Type t, Type s) {
329 return isSubtype(t, s, false);
330 }
331 public boolean isSubtype(Type t, Type s, boolean capture) {
332 if (t == s)
333 return true;
335 if (s.tag >= firstPartialTag)
336 return isSuperType(s, t);
338 Type lower = lowerBound(s);
339 if (s != lower)
340 return isSubtype(capture ? capture(t) : t, lower, false);
342 return isSubtype.visit(capture ? capture(t) : t, s);
343 }
344 // where
345 private TypeRelation isSubtype = new TypeRelation()
346 {
347 public Boolean visitType(Type t, Type s) {
348 switch (t.tag) {
349 case BYTE: case CHAR:
350 return (t.tag == s.tag ||
351 t.tag + 2 <= s.tag && s.tag <= DOUBLE);
352 case SHORT: case INT: case LONG: case FLOAT: case DOUBLE:
353 return t.tag <= s.tag && s.tag <= DOUBLE;
354 case BOOLEAN: case VOID:
355 return t.tag == s.tag;
356 case TYPEVAR:
357 return isSubtypeNoCapture(t.getUpperBound(), s);
358 case BOT:
359 return
360 s.tag == BOT || s.tag == CLASS ||
361 s.tag == ARRAY || s.tag == TYPEVAR;
362 case NONE:
363 return false;
364 default:
365 throw new AssertionError("isSubtype " + t.tag);
366 }
367 }
369 private Set<TypePair> cache = new HashSet<TypePair>();
371 private boolean containsTypeRecursive(Type t, Type s) {
372 TypePair pair = new TypePair(t, s);
373 if (cache.add(pair)) {
374 try {
375 return containsType(t.getTypeArguments(),
376 s.getTypeArguments());
377 } finally {
378 cache.remove(pair);
379 }
380 } else {
381 return containsType(t.getTypeArguments(),
382 rewriteSupers(s).getTypeArguments());
383 }
384 }
386 private Type rewriteSupers(Type t) {
387 if (!t.isParameterized())
388 return t;
389 ListBuffer<Type> from = lb();
390 ListBuffer<Type> to = lb();
391 adaptSelf(t, from, to);
392 if (from.isEmpty())
393 return t;
394 ListBuffer<Type> rewrite = lb();
395 boolean changed = false;
396 for (Type orig : to.toList()) {
397 Type s = rewriteSupers(orig);
398 if (s.isSuperBound() && !s.isExtendsBound()) {
399 s = new WildcardType(syms.objectType,
400 BoundKind.UNBOUND,
401 syms.boundClass);
402 changed = true;
403 } else if (s != orig) {
404 s = new WildcardType(upperBound(s),
405 BoundKind.EXTENDS,
406 syms.boundClass);
407 changed = true;
408 }
409 rewrite.append(s);
410 }
411 if (changed)
412 return subst(t.tsym.type, from.toList(), rewrite.toList());
413 else
414 return t;
415 }
417 @Override
418 public Boolean visitClassType(ClassType t, Type s) {
419 Type sup = asSuper(t, s.tsym);
420 return sup != null
421 && sup.tsym == s.tsym
422 // You're not allowed to write
423 // Vector<Object> vec = new Vector<String>();
424 // But with wildcards you can write
425 // Vector<? extends Object> vec = new Vector<String>();
426 // which means that subtype checking must be done
427 // here instead of same-type checking (via containsType).
428 && (!s.isParameterized() || containsTypeRecursive(s, sup))
429 && isSubtypeNoCapture(sup.getEnclosingType(),
430 s.getEnclosingType());
431 }
433 @Override
434 public Boolean visitArrayType(ArrayType t, Type s) {
435 if (s.tag == ARRAY) {
436 if (t.elemtype.tag <= lastBaseTag)
437 return isSameType(t.elemtype, elemtype(s));
438 else
439 return isSubtypeNoCapture(t.elemtype, elemtype(s));
440 }
442 if (s.tag == CLASS) {
443 Name sname = s.tsym.getQualifiedName();
444 return sname == names.java_lang_Object
445 || sname == names.java_lang_Cloneable
446 || sname == names.java_io_Serializable;
447 }
449 return false;
450 }
452 @Override
453 public Boolean visitUndetVar(UndetVar t, Type s) {
454 //todo: test against origin needed? or replace with substitution?
455 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
456 return true;
458 if (t.inst != null)
459 return isSubtypeNoCapture(t.inst, s); // TODO: ", warn"?
461 t.hibounds = t.hibounds.prepend(s);
462 return true;
463 }
465 @Override
466 public Boolean visitErrorType(ErrorType t, Type s) {
467 return true;
468 }
469 };
471 /**
472 * Is t a subtype of every type in given list `ts'?<br>
473 * (not defined for Method and ForAll types)<br>
474 * Allows unchecked conversions.
475 */
476 public boolean isSubtypeUnchecked(Type t, List<Type> ts, Warner warn) {
477 for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
478 if (!isSubtypeUnchecked(t, l.head, warn))
479 return false;
480 return true;
481 }
483 /**
484 * Are corresponding elements of ts subtypes of ss? If lists are
485 * of different length, return false.
486 */
487 public boolean isSubtypes(List<Type> ts, List<Type> ss) {
488 while (ts.tail != null && ss.tail != null
489 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
490 isSubtype(ts.head, ss.head)) {
491 ts = ts.tail;
492 ss = ss.tail;
493 }
494 return ts.tail == null && ss.tail == null;
495 /*inlined: ts.isEmpty() && ss.isEmpty();*/
496 }
498 /**
499 * Are corresponding elements of ts subtypes of ss, allowing
500 * unchecked conversions? If lists are of different length,
501 * return false.
502 **/
503 public boolean isSubtypesUnchecked(List<Type> ts, List<Type> ss, Warner warn) {
504 while (ts.tail != null && ss.tail != null
505 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
506 isSubtypeUnchecked(ts.head, ss.head, warn)) {
507 ts = ts.tail;
508 ss = ss.tail;
509 }
510 return ts.tail == null && ss.tail == null;
511 /*inlined: ts.isEmpty() && ss.isEmpty();*/
512 }
513 // </editor-fold>
515 // <editor-fold defaultstate="collapsed" desc="isSuperType">
516 /**
517 * Is t a supertype of s?
518 */
519 public boolean isSuperType(Type t, Type s) {
520 switch (t.tag) {
521 case ERROR:
522 return true;
523 case UNDETVAR: {
524 UndetVar undet = (UndetVar)t;
525 if (t == s ||
526 undet.qtype == s ||
527 s.tag == ERROR ||
528 s.tag == BOT) return true;
529 if (undet.inst != null)
530 return isSubtype(s, undet.inst);
531 undet.lobounds = undet.lobounds.prepend(s);
532 return true;
533 }
534 default:
535 return isSubtype(s, t);
536 }
537 }
538 // </editor-fold>
540 // <editor-fold defaultstate="collapsed" desc="isSameType">
541 /**
542 * Are corresponding elements of the lists the same type? If
543 * lists are of different length, return false.
544 */
545 public boolean isSameTypes(List<Type> ts, List<Type> ss) {
546 while (ts.tail != null && ss.tail != null
547 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
548 isSameType(ts.head, ss.head)) {
549 ts = ts.tail;
550 ss = ss.tail;
551 }
552 return ts.tail == null && ss.tail == null;
553 /*inlined: ts.isEmpty() && ss.isEmpty();*/
554 }
556 /**
557 * Is t the same type as s?
558 */
559 public boolean isSameType(Type t, Type s) {
560 return isSameType.visit(t, s);
561 }
562 // where
563 private TypeRelation isSameType = new TypeRelation() {
565 public Boolean visitType(Type t, Type s) {
566 if (t == s)
567 return true;
569 if (s.tag >= firstPartialTag)
570 return visit(s, t);
572 switch (t.tag) {
573 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
574 case DOUBLE: case BOOLEAN: case VOID: case BOT: case NONE:
575 return t.tag == s.tag;
576 case TYPEVAR:
577 return s.isSuperBound()
578 && !s.isExtendsBound()
579 && visit(t, upperBound(s));
580 default:
581 throw new AssertionError("isSameType " + t.tag);
582 }
583 }
585 @Override
586 public Boolean visitWildcardType(WildcardType t, Type s) {
587 if (s.tag >= firstPartialTag)
588 return visit(s, t);
589 else
590 return false;
591 }
593 @Override
594 public Boolean visitClassType(ClassType t, Type s) {
595 if (t == s)
596 return true;
598 if (s.tag >= firstPartialTag)
599 return visit(s, t);
601 if (s.isSuperBound() && !s.isExtendsBound())
602 return visit(t, upperBound(s)) && visit(t, lowerBound(s));
604 if (t.isCompound() && s.isCompound()) {
605 if (!visit(supertype(t), supertype(s)))
606 return false;
608 HashSet<SingletonType> set = new HashSet<SingletonType>();
609 for (Type x : interfaces(t))
610 set.add(new SingletonType(x));
611 for (Type x : interfaces(s)) {
612 if (!set.remove(new SingletonType(x)))
613 return false;
614 }
615 return (set.size() == 0);
616 }
617 return t.tsym == s.tsym
618 && visit(t.getEnclosingType(), s.getEnclosingType())
619 && containsTypeEquivalent(t.getTypeArguments(), s.getTypeArguments());
620 }
622 @Override
623 public Boolean visitArrayType(ArrayType t, Type s) {
624 if (t == s)
625 return true;
627 if (s.tag >= firstPartialTag)
628 return visit(s, t);
630 return s.tag == ARRAY
631 && containsTypeEquivalent(t.elemtype, elemtype(s));
632 }
634 @Override
635 public Boolean visitMethodType(MethodType t, Type s) {
636 // isSameType for methods does not take thrown
637 // exceptions into account!
638 return hasSameArgs(t, s) && visit(t.getReturnType(), s.getReturnType());
639 }
641 @Override
642 public Boolean visitPackageType(PackageType t, Type s) {
643 return t == s;
644 }
646 @Override
647 public Boolean visitForAll(ForAll t, Type s) {
648 if (s.tag != FORALL)
649 return false;
651 ForAll forAll = (ForAll)s;
652 return hasSameBounds(t, forAll)
653 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
654 }
656 @Override
657 public Boolean visitUndetVar(UndetVar t, Type s) {
658 if (s.tag == WILDCARD)
659 // FIXME, this might be leftovers from before capture conversion
660 return false;
662 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
663 return true;
665 if (t.inst != null)
666 return visit(t.inst, s);
668 t.inst = fromUnknownFun.apply(s);
669 for (List<Type> l = t.lobounds; l.nonEmpty(); l = l.tail) {
670 if (!isSubtype(l.head, t.inst))
671 return false;
672 }
673 for (List<Type> l = t.hibounds; l.nonEmpty(); l = l.tail) {
674 if (!isSubtype(t.inst, l.head))
675 return false;
676 }
677 return true;
678 }
680 @Override
681 public Boolean visitErrorType(ErrorType t, Type s) {
682 return true;
683 }
684 };
685 // </editor-fold>
687 // <editor-fold defaultstate="collapsed" desc="fromUnknownFun">
688 /**
689 * A mapping that turns all unknown types in this type to fresh
690 * unknown variables.
691 */
692 public Mapping fromUnknownFun = new Mapping("fromUnknownFun") {
693 public Type apply(Type t) {
694 if (t.tag == UNKNOWN) return new UndetVar(t);
695 else return t.map(this);
696 }
697 };
698 // </editor-fold>
700 // <editor-fold defaultstate="collapsed" desc="Contains Type">
701 public boolean containedBy(Type t, Type s) {
702 switch (t.tag) {
703 case UNDETVAR:
704 if (s.tag == WILDCARD) {
705 UndetVar undetvar = (UndetVar)t;
707 // Because of wildcard capture, s must be on the left
708 // hand side of an assignment. Furthermore, t is an
709 // underconstrained type variable, for example, one
710 // that is only used in the return type of a method.
711 // If the type variable is truly underconstrained, it
712 // cannot have any low bounds:
713 assert undetvar.lobounds.isEmpty() : undetvar;
715 undetvar.inst = glb(upperBound(s), undetvar.inst);
716 return true;
717 } else {
718 return isSameType(t, s);
719 }
720 case ERROR:
721 return true;
722 default:
723 return containsType(s, t);
724 }
725 }
727 boolean containsType(List<Type> ts, List<Type> ss) {
728 while (ts.nonEmpty() && ss.nonEmpty()
729 && containsType(ts.head, ss.head)) {
730 ts = ts.tail;
731 ss = ss.tail;
732 }
733 return ts.isEmpty() && ss.isEmpty();
734 }
736 /**
737 * Check if t contains s.
738 *
739 * <p>T contains S if:
740 *
741 * <p>{@code L(T) <: L(S) && U(S) <: U(T)}
742 *
743 * <p>This relation is only used by ClassType.isSubtype(), that
744 * is,
745 *
746 * <p>{@code C<S> <: C<T> if T contains S.}
747 *
748 * <p>Because of F-bounds, this relation can lead to infinite
749 * recursion. Thus we must somehow break that recursion. Notice
750 * that containsType() is only called from ClassType.isSubtype().
751 * Since the arguments have already been checked against their
752 * bounds, we know:
753 *
754 * <p>{@code U(S) <: U(T) if T is "super" bound (U(T) *is* the bound)}
755 *
756 * <p>{@code L(T) <: L(S) if T is "extends" bound (L(T) is bottom)}
757 *
758 * @param t a type
759 * @param s a type
760 */
761 public boolean containsType(Type t, Type s) {
762 return containsType.visit(t, s);
763 }
764 // where
765 private TypeRelation containsType = new TypeRelation() {
767 private Type U(Type t) {
768 while (t.tag == WILDCARD) {
769 WildcardType w = (WildcardType)t;
770 if (w.isSuperBound())
771 return w.bound == null ? syms.objectType : w.bound.bound;
772 else
773 t = w.type;
774 }
775 return t;
776 }
778 private Type L(Type t) {
779 while (t.tag == WILDCARD) {
780 WildcardType w = (WildcardType)t;
781 if (w.isExtendsBound())
782 return syms.botType;
783 else
784 t = w.type;
785 }
786 return t;
787 }
789 public Boolean visitType(Type t, Type s) {
790 if (s.tag >= firstPartialTag)
791 return containedBy(s, t);
792 else
793 return isSameType(t, s);
794 }
796 void debugContainsType(WildcardType t, Type s) {
797 System.err.println();
798 System.err.format(" does %s contain %s?%n", t, s);
799 System.err.format(" %s U(%s) <: U(%s) %s = %s%n",
800 upperBound(s), s, t, U(t),
801 t.isSuperBound()
802 || isSubtypeNoCapture(upperBound(s), U(t)));
803 System.err.format(" %s L(%s) <: L(%s) %s = %s%n",
804 L(t), t, s, lowerBound(s),
805 t.isExtendsBound()
806 || isSubtypeNoCapture(L(t), lowerBound(s)));
807 System.err.println();
808 }
810 @Override
811 public Boolean visitWildcardType(WildcardType t, Type s) {
812 if (s.tag >= firstPartialTag)
813 return containedBy(s, t);
814 else {
815 // debugContainsType(t, s);
816 return isSameWildcard(t, s)
817 || isCaptureOf(s, t)
818 || ((t.isExtendsBound() || isSubtypeNoCapture(L(t), lowerBound(s))) &&
819 (t.isSuperBound() || isSubtypeNoCapture(upperBound(s), U(t))));
820 }
821 }
823 @Override
824 public Boolean visitUndetVar(UndetVar t, Type s) {
825 if (s.tag != WILDCARD)
826 return isSameType(t, s);
827 else
828 return false;
829 }
831 @Override
832 public Boolean visitErrorType(ErrorType t, Type s) {
833 return true;
834 }
835 };
837 public boolean isCaptureOf(Type s, WildcardType t) {
838 if (s.tag != TYPEVAR || !(s instanceof CapturedType))
839 return false;
840 return isSameWildcard(t, ((CapturedType)s).wildcard);
841 }
843 public boolean isSameWildcard(WildcardType t, Type s) {
844 if (s.tag != WILDCARD)
845 return false;
846 WildcardType w = (WildcardType)s;
847 return w.kind == t.kind && w.type == t.type;
848 }
850 public boolean containsTypeEquivalent(List<Type> ts, List<Type> ss) {
851 while (ts.nonEmpty() && ss.nonEmpty()
852 && containsTypeEquivalent(ts.head, ss.head)) {
853 ts = ts.tail;
854 ss = ss.tail;
855 }
856 return ts.isEmpty() && ss.isEmpty();
857 }
858 // </editor-fold>
860 // <editor-fold defaultstate="collapsed" desc="isCastable">
861 public boolean isCastable(Type t, Type s) {
862 return isCastable(t, s, Warner.noWarnings);
863 }
865 /**
866 * Is t is castable to s?<br>
867 * s is assumed to be an erased type.<br>
868 * (not defined for Method and ForAll types).
869 */
870 public boolean isCastable(Type t, Type s, Warner warn) {
871 if (t == s)
872 return true;
874 if (t.isPrimitive() != s.isPrimitive())
875 return allowBoxing && isConvertible(t, s, warn);
877 if (warn != warnStack.head) {
878 try {
879 warnStack = warnStack.prepend(warn);
880 return isCastable.visit(t, s);
881 } finally {
882 warnStack = warnStack.tail;
883 }
884 } else {
885 return isCastable.visit(t, s);
886 }
887 }
888 // where
889 private TypeRelation isCastable = new TypeRelation() {
891 public Boolean visitType(Type t, Type s) {
892 if (s.tag == ERROR)
893 return true;
895 switch (t.tag) {
896 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
897 case DOUBLE:
898 return s.tag <= DOUBLE;
899 case BOOLEAN:
900 return s.tag == BOOLEAN;
901 case VOID:
902 return false;
903 case BOT:
904 return isSubtype(t, s);
905 default:
906 throw new AssertionError();
907 }
908 }
910 @Override
911 public Boolean visitWildcardType(WildcardType t, Type s) {
912 return isCastable(upperBound(t), s, warnStack.head);
913 }
915 @Override
916 public Boolean visitClassType(ClassType t, Type s) {
917 if (s.tag == ERROR || s.tag == BOT)
918 return true;
920 if (s.tag == TYPEVAR) {
921 if (isCastable(s.getUpperBound(), t, Warner.noWarnings)) {
922 warnStack.head.warnUnchecked();
923 return true;
924 } else {
925 return false;
926 }
927 }
929 if (t.isCompound()) {
930 if (!visit(supertype(t), s))
931 return false;
932 for (Type intf : interfaces(t)) {
933 if (!visit(intf, s))
934 return false;
935 }
936 return true;
937 }
939 if (s.isCompound()) {
940 // call recursively to reuse the above code
941 return visitClassType((ClassType)s, t);
942 }
944 if (s.tag == CLASS || s.tag == ARRAY) {
945 boolean upcast;
946 if ((upcast = isSubtype(erasure(t), erasure(s)))
947 || isSubtype(erasure(s), erasure(t))) {
948 if (!upcast && s.tag == ARRAY) {
949 if (!isReifiable(s))
950 warnStack.head.warnUnchecked();
951 return true;
952 } else if (s.isRaw()) {
953 return true;
954 } else if (t.isRaw()) {
955 if (!isUnbounded(s))
956 warnStack.head.warnUnchecked();
957 return true;
958 }
959 // Assume |a| <: |b|
960 final Type a = upcast ? t : s;
961 final Type b = upcast ? s : t;
962 final boolean HIGH = true;
963 final boolean LOW = false;
964 final boolean DONT_REWRITE_TYPEVARS = false;
965 Type aHigh = rewriteQuantifiers(a, HIGH, DONT_REWRITE_TYPEVARS);
966 Type aLow = rewriteQuantifiers(a, LOW, DONT_REWRITE_TYPEVARS);
967 Type bHigh = rewriteQuantifiers(b, HIGH, DONT_REWRITE_TYPEVARS);
968 Type bLow = rewriteQuantifiers(b, LOW, DONT_REWRITE_TYPEVARS);
969 Type lowSub = asSub(bLow, aLow.tsym);
970 Type highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
971 if (highSub == null) {
972 final boolean REWRITE_TYPEVARS = true;
973 aHigh = rewriteQuantifiers(a, HIGH, REWRITE_TYPEVARS);
974 aLow = rewriteQuantifiers(a, LOW, REWRITE_TYPEVARS);
975 bHigh = rewriteQuantifiers(b, HIGH, REWRITE_TYPEVARS);
976 bLow = rewriteQuantifiers(b, LOW, REWRITE_TYPEVARS);
977 lowSub = asSub(bLow, aLow.tsym);
978 highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
979 }
980 if (highSub != null) {
981 assert a.tsym == highSub.tsym && a.tsym == lowSub.tsym
982 : a.tsym + " != " + highSub.tsym + " != " + lowSub.tsym;
983 if (!disjointTypes(aHigh.getTypeArguments(), highSub.getTypeArguments())
984 && !disjointTypes(aHigh.getTypeArguments(), lowSub.getTypeArguments())
985 && !disjointTypes(aLow.getTypeArguments(), highSub.getTypeArguments())
986 && !disjointTypes(aLow.getTypeArguments(), lowSub.getTypeArguments())) {
987 if (upcast ? giveWarning(a, highSub) || giveWarning(a, lowSub)
988 : giveWarning(highSub, a) || giveWarning(lowSub, a))
989 warnStack.head.warnUnchecked();
990 return true;
991 }
992 }
993 if (isReifiable(s))
994 return isSubtypeUnchecked(a, b);
995 else
996 return isSubtypeUnchecked(a, b, warnStack.head);
997 }
999 // Sidecast
1000 if (s.tag == CLASS) {
1001 if ((s.tsym.flags() & INTERFACE) != 0) {
1002 return ((t.tsym.flags() & FINAL) == 0)
1003 ? sideCast(t, s, warnStack.head)
1004 : sideCastFinal(t, s, warnStack.head);
1005 } else if ((t.tsym.flags() & INTERFACE) != 0) {
1006 return ((s.tsym.flags() & FINAL) == 0)
1007 ? sideCast(t, s, warnStack.head)
1008 : sideCastFinal(t, s, warnStack.head);
1009 } else {
1010 // unrelated class types
1011 return false;
1012 }
1013 }
1014 }
1015 return false;
1016 }
1018 @Override
1019 public Boolean visitArrayType(ArrayType t, Type s) {
1020 switch (s.tag) {
1021 case ERROR:
1022 case BOT:
1023 return true;
1024 case TYPEVAR:
1025 if (isCastable(s, t, Warner.noWarnings)) {
1026 warnStack.head.warnUnchecked();
1027 return true;
1028 } else {
1029 return false;
1030 }
1031 case CLASS:
1032 return isSubtype(t, s);
1033 case ARRAY:
1034 if (elemtype(t).tag <= lastBaseTag) {
1035 return elemtype(t).tag == elemtype(s).tag;
1036 } else {
1037 return visit(elemtype(t), elemtype(s));
1038 }
1039 default:
1040 return false;
1041 }
1042 }
1044 @Override
1045 public Boolean visitTypeVar(TypeVar t, Type s) {
1046 switch (s.tag) {
1047 case ERROR:
1048 case BOT:
1049 return true;
1050 case TYPEVAR:
1051 if (isSubtype(t, s)) {
1052 return true;
1053 } else if (isCastable(t.bound, s, Warner.noWarnings)) {
1054 warnStack.head.warnUnchecked();
1055 return true;
1056 } else {
1057 return false;
1058 }
1059 default:
1060 return isCastable(t.bound, s, warnStack.head);
1061 }
1062 }
1064 @Override
1065 public Boolean visitErrorType(ErrorType t, Type s) {
1066 return true;
1067 }
1068 };
1069 // </editor-fold>
1071 // <editor-fold defaultstate="collapsed" desc="disjointTypes">
1072 public boolean disjointTypes(List<Type> ts, List<Type> ss) {
1073 while (ts.tail != null && ss.tail != null) {
1074 if (disjointType(ts.head, ss.head)) return true;
1075 ts = ts.tail;
1076 ss = ss.tail;
1077 }
1078 return false;
1079 }
1081 /**
1082 * Two types or wildcards are considered disjoint if it can be
1083 * proven that no type can be contained in both. It is
1084 * conservative in that it is allowed to say that two types are
1085 * not disjoint, even though they actually are.
1086 *
1087 * The type C<X> is castable to C<Y> exactly if X and Y are not
1088 * disjoint.
1089 */
1090 public boolean disjointType(Type t, Type s) {
1091 return disjointType.visit(t, s);
1092 }
1093 // where
1094 private TypeRelation disjointType = new TypeRelation() {
1096 private Set<TypePair> cache = new HashSet<TypePair>();
1098 public Boolean visitType(Type t, Type s) {
1099 if (s.tag == WILDCARD)
1100 return visit(s, t);
1101 else
1102 return notSoftSubtypeRecursive(t, s) || notSoftSubtypeRecursive(s, t);
1103 }
1105 private boolean isCastableRecursive(Type t, Type s) {
1106 TypePair pair = new TypePair(t, s);
1107 if (cache.add(pair)) {
1108 try {
1109 return Types.this.isCastable(t, s);
1110 } finally {
1111 cache.remove(pair);
1112 }
1113 } else {
1114 return true;
1115 }
1116 }
1118 private boolean notSoftSubtypeRecursive(Type t, Type s) {
1119 TypePair pair = new TypePair(t, s);
1120 if (cache.add(pair)) {
1121 try {
1122 return Types.this.notSoftSubtype(t, s);
1123 } finally {
1124 cache.remove(pair);
1125 }
1126 } else {
1127 return false;
1128 }
1129 }
1131 @Override
1132 public Boolean visitWildcardType(WildcardType t, Type s) {
1133 if (t.isUnbound())
1134 return false;
1136 if (s.tag != WILDCARD) {
1137 if (t.isExtendsBound())
1138 return notSoftSubtypeRecursive(s, t.type);
1139 else // isSuperBound()
1140 return notSoftSubtypeRecursive(t.type, s);
1141 }
1143 if (s.isUnbound())
1144 return false;
1146 if (t.isExtendsBound()) {
1147 if (s.isExtendsBound())
1148 return !isCastableRecursive(t.type, upperBound(s));
1149 else if (s.isSuperBound())
1150 return notSoftSubtypeRecursive(lowerBound(s), t.type);
1151 } else if (t.isSuperBound()) {
1152 if (s.isExtendsBound())
1153 return notSoftSubtypeRecursive(t.type, upperBound(s));
1154 }
1155 return false;
1156 }
1157 };
1158 // </editor-fold>
1160 // <editor-fold defaultstate="collapsed" desc="lowerBoundArgtypes">
1161 /**
1162 * Returns the lower bounds of the formals of a method.
1163 */
1164 public List<Type> lowerBoundArgtypes(Type t) {
1165 return map(t.getParameterTypes(), lowerBoundMapping);
1166 }
1167 private final Mapping lowerBoundMapping = new Mapping("lowerBound") {
1168 public Type apply(Type t) {
1169 return lowerBound(t);
1170 }
1171 };
1172 // </editor-fold>
1174 // <editor-fold defaultstate="collapsed" desc="notSoftSubtype">
1175 /**
1176 * This relation answers the question: is impossible that
1177 * something of type `t' can be a subtype of `s'? This is
1178 * different from the question "is `t' not a subtype of `s'?"
1179 * when type variables are involved: Integer is not a subtype of T
1180 * where <T extends Number> but it is not true that Integer cannot
1181 * possibly be a subtype of T.
1182 */
1183 public boolean notSoftSubtype(Type t, Type s) {
1184 if (t == s) return false;
1185 if (t.tag == TYPEVAR) {
1186 TypeVar tv = (TypeVar) t;
1187 if (s.tag == TYPEVAR)
1188 s = s.getUpperBound();
1189 return !isCastable(tv.bound,
1190 s,
1191 Warner.noWarnings);
1192 }
1193 if (s.tag != WILDCARD)
1194 s = upperBound(s);
1195 if (s.tag == TYPEVAR)
1196 s = s.getUpperBound();
1197 return !isSubtype(t, s);
1198 }
1199 // </editor-fold>
1201 // <editor-fold defaultstate="collapsed" desc="isReifiable">
1202 public boolean isReifiable(Type t) {
1203 return isReifiable.visit(t);
1204 }
1205 // where
1206 private UnaryVisitor<Boolean> isReifiable = new UnaryVisitor<Boolean>() {
1208 public Boolean visitType(Type t, Void ignored) {
1209 return true;
1210 }
1212 @Override
1213 public Boolean visitClassType(ClassType t, Void ignored) {
1214 if (!t.isParameterized())
1215 return true;
1217 for (Type param : t.allparams()) {
1218 if (!param.isUnbound())
1219 return false;
1220 }
1221 return true;
1222 }
1224 @Override
1225 public Boolean visitArrayType(ArrayType t, Void ignored) {
1226 return visit(t.elemtype);
1227 }
1229 @Override
1230 public Boolean visitTypeVar(TypeVar t, Void ignored) {
1231 return false;
1232 }
1233 };
1234 // </editor-fold>
1236 // <editor-fold defaultstate="collapsed" desc="Array Utils">
1237 public boolean isArray(Type t) {
1238 while (t.tag == WILDCARD)
1239 t = upperBound(t);
1240 return t.tag == ARRAY;
1241 }
1243 /**
1244 * The element type of an array.
1245 */
1246 public Type elemtype(Type t) {
1247 switch (t.tag) {
1248 case WILDCARD:
1249 return elemtype(upperBound(t));
1250 case ARRAY:
1251 return ((ArrayType)t).elemtype;
1252 case FORALL:
1253 return elemtype(((ForAll)t).qtype);
1254 case ERROR:
1255 return t;
1256 default:
1257 return null;
1258 }
1259 }
1261 /**
1262 * Mapping to take element type of an arraytype
1263 */
1264 private Mapping elemTypeFun = new Mapping ("elemTypeFun") {
1265 public Type apply(Type t) { return elemtype(t); }
1266 };
1268 /**
1269 * The number of dimensions of an array type.
1270 */
1271 public int dimensions(Type t) {
1272 int result = 0;
1273 while (t.tag == ARRAY) {
1274 result++;
1275 t = elemtype(t);
1276 }
1277 return result;
1278 }
1279 // </editor-fold>
1281 // <editor-fold defaultstate="collapsed" desc="asSuper">
1282 /**
1283 * Return the (most specific) base type of t that starts with the
1284 * given symbol. If none exists, return null.
1285 *
1286 * @param t a type
1287 * @param sym a symbol
1288 */
1289 public Type asSuper(Type t, Symbol sym) {
1290 return asSuper.visit(t, sym);
1291 }
1292 // where
1293 private SimpleVisitor<Type,Symbol> asSuper = new SimpleVisitor<Type,Symbol>() {
1295 public Type visitType(Type t, Symbol sym) {
1296 return null;
1297 }
1299 @Override
1300 public Type visitClassType(ClassType t, Symbol sym) {
1301 if (t.tsym == sym)
1302 return t;
1304 Type st = supertype(t);
1305 if (st.tag == CLASS || st.tag == TYPEVAR || st.tag == ERROR) {
1306 Type x = asSuper(st, sym);
1307 if (x != null)
1308 return x;
1309 }
1310 if ((sym.flags() & INTERFACE) != 0) {
1311 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
1312 Type x = asSuper(l.head, sym);
1313 if (x != null)
1314 return x;
1315 }
1316 }
1317 return null;
1318 }
1320 @Override
1321 public Type visitArrayType(ArrayType t, Symbol sym) {
1322 return isSubtype(t, sym.type) ? sym.type : null;
1323 }
1325 @Override
1326 public Type visitTypeVar(TypeVar t, Symbol sym) {
1327 if (t.tsym == sym)
1328 return t;
1329 else
1330 return asSuper(t.bound, sym);
1331 }
1333 @Override
1334 public Type visitErrorType(ErrorType t, Symbol sym) {
1335 return t;
1336 }
1337 };
1339 /**
1340 * Return the base type of t or any of its outer types that starts
1341 * with the given symbol. If none exists, return null.
1342 *
1343 * @param t a type
1344 * @param sym a symbol
1345 */
1346 public Type asOuterSuper(Type t, Symbol sym) {
1347 switch (t.tag) {
1348 case CLASS:
1349 do {
1350 Type s = asSuper(t, sym);
1351 if (s != null) return s;
1352 t = t.getEnclosingType();
1353 } while (t.tag == CLASS);
1354 return null;
1355 case ARRAY:
1356 return isSubtype(t, sym.type) ? sym.type : null;
1357 case TYPEVAR:
1358 return asSuper(t, sym);
1359 case ERROR:
1360 return t;
1361 default:
1362 return null;
1363 }
1364 }
1366 /**
1367 * Return the base type of t or any of its enclosing types that
1368 * starts with the given symbol. If none exists, return null.
1369 *
1370 * @param t a type
1371 * @param sym a symbol
1372 */
1373 public Type asEnclosingSuper(Type t, Symbol sym) {
1374 switch (t.tag) {
1375 case CLASS:
1376 do {
1377 Type s = asSuper(t, sym);
1378 if (s != null) return s;
1379 Type outer = t.getEnclosingType();
1380 t = (outer.tag == CLASS) ? outer :
1381 (t.tsym.owner.enclClass() != null) ? t.tsym.owner.enclClass().type :
1382 Type.noType;
1383 } while (t.tag == CLASS);
1384 return null;
1385 case ARRAY:
1386 return isSubtype(t, sym.type) ? sym.type : null;
1387 case TYPEVAR:
1388 return asSuper(t, sym);
1389 case ERROR:
1390 return t;
1391 default:
1392 return null;
1393 }
1394 }
1395 // </editor-fold>
1397 // <editor-fold defaultstate="collapsed" desc="memberType">
1398 /**
1399 * The type of given symbol, seen as a member of t.
1400 *
1401 * @param t a type
1402 * @param sym a symbol
1403 */
1404 public Type memberType(Type t, Symbol sym) {
1405 return (sym.flags() & STATIC) != 0
1406 ? sym.type
1407 : memberType.visit(t, sym);
1408 }
1409 // where
1410 private SimpleVisitor<Type,Symbol> memberType = new SimpleVisitor<Type,Symbol>() {
1412 public Type visitType(Type t, Symbol sym) {
1413 return sym.type;
1414 }
1416 @Override
1417 public Type visitWildcardType(WildcardType t, Symbol sym) {
1418 return memberType(upperBound(t), sym);
1419 }
1421 @Override
1422 public Type visitClassType(ClassType t, Symbol sym) {
1423 Symbol owner = sym.owner;
1424 long flags = sym.flags();
1425 if (((flags & STATIC) == 0) && owner.type.isParameterized()) {
1426 Type base = asOuterSuper(t, owner);
1427 if (base != null) {
1428 List<Type> ownerParams = owner.type.allparams();
1429 List<Type> baseParams = base.allparams();
1430 if (ownerParams.nonEmpty()) {
1431 if (baseParams.isEmpty()) {
1432 // then base is a raw type
1433 return erasure(sym.type);
1434 } else {
1435 return subst(sym.type, ownerParams, baseParams);
1436 }
1437 }
1438 }
1439 }
1440 return sym.type;
1441 }
1443 @Override
1444 public Type visitTypeVar(TypeVar t, Symbol sym) {
1445 return memberType(t.bound, sym);
1446 }
1448 @Override
1449 public Type visitErrorType(ErrorType t, Symbol sym) {
1450 return t;
1451 }
1452 };
1453 // </editor-fold>
1455 // <editor-fold defaultstate="collapsed" desc="isAssignable">
1456 public boolean isAssignable(Type t, Type s) {
1457 return isAssignable(t, s, Warner.noWarnings);
1458 }
1460 /**
1461 * Is t assignable to s?<br>
1462 * Equivalent to subtype except for constant values and raw
1463 * types.<br>
1464 * (not defined for Method and ForAll types)
1465 */
1466 public boolean isAssignable(Type t, Type s, Warner warn) {
1467 if (t.tag == ERROR)
1468 return true;
1469 if (t.tag <= INT && t.constValue() != null) {
1470 int value = ((Number)t.constValue()).intValue();
1471 switch (s.tag) {
1472 case BYTE:
1473 if (Byte.MIN_VALUE <= value && value <= Byte.MAX_VALUE)
1474 return true;
1475 break;
1476 case CHAR:
1477 if (Character.MIN_VALUE <= value && value <= Character.MAX_VALUE)
1478 return true;
1479 break;
1480 case SHORT:
1481 if (Short.MIN_VALUE <= value && value <= Short.MAX_VALUE)
1482 return true;
1483 break;
1484 case INT:
1485 return true;
1486 case CLASS:
1487 switch (unboxedType(s).tag) {
1488 case BYTE:
1489 case CHAR:
1490 case SHORT:
1491 return isAssignable(t, unboxedType(s), warn);
1492 }
1493 break;
1494 }
1495 }
1496 return isConvertible(t, s, warn);
1497 }
1498 // </editor-fold>
1500 // <editor-fold defaultstate="collapsed" desc="erasure">
1501 /**
1502 * The erasure of t {@code |t|} -- the type that results when all
1503 * type parameters in t are deleted.
1504 */
1505 public Type erasure(Type t) {
1506 return erasure(t, false);
1507 }
1508 //where
1509 private Type erasure(Type t, boolean recurse) {
1510 if (t.tag <= lastBaseTag)
1511 return t; /* fast special case */
1512 else
1513 return erasure.visit(t, recurse);
1514 }
1515 // where
1516 private SimpleVisitor<Type, Boolean> erasure = new SimpleVisitor<Type, Boolean>() {
1517 public Type visitType(Type t, Boolean recurse) {
1518 if (t.tag <= lastBaseTag)
1519 return t; /*fast special case*/
1520 else
1521 return t.map(recurse ? erasureRecFun : erasureFun);
1522 }
1524 @Override
1525 public Type visitWildcardType(WildcardType t, Boolean recurse) {
1526 return erasure(upperBound(t), recurse);
1527 }
1529 @Override
1530 public Type visitClassType(ClassType t, Boolean recurse) {
1531 Type erased = t.tsym.erasure(Types.this);
1532 if (recurse) {
1533 erased = new ErasedClassType(erased.getEnclosingType(),erased.tsym);
1534 }
1535 return erased;
1536 }
1538 @Override
1539 public Type visitTypeVar(TypeVar t, Boolean recurse) {
1540 return erasure(t.bound, recurse);
1541 }
1543 @Override
1544 public Type visitErrorType(ErrorType t, Boolean recurse) {
1545 return t;
1546 }
1547 };
1549 private Mapping erasureFun = new Mapping ("erasure") {
1550 public Type apply(Type t) { return erasure(t); }
1551 };
1553 private Mapping erasureRecFun = new Mapping ("erasureRecursive") {
1554 public Type apply(Type t) { return erasureRecursive(t); }
1555 };
1557 public List<Type> erasure(List<Type> ts) {
1558 return Type.map(ts, erasureFun);
1559 }
1561 public Type erasureRecursive(Type t) {
1562 return erasure(t, true);
1563 }
1565 public List<Type> erasureRecursive(List<Type> ts) {
1566 return Type.map(ts, erasureRecFun);
1567 }
1568 // </editor-fold>
1570 // <editor-fold defaultstate="collapsed" desc="makeCompoundType">
1571 /**
1572 * Make a compound type from non-empty list of types
1573 *
1574 * @param bounds the types from which the compound type is formed
1575 * @param supertype is objectType if all bounds are interfaces,
1576 * null otherwise.
1577 */
1578 public Type makeCompoundType(List<Type> bounds,
1579 Type supertype) {
1580 ClassSymbol bc =
1581 new ClassSymbol(ABSTRACT|PUBLIC|SYNTHETIC|COMPOUND|ACYCLIC,
1582 Type.moreInfo
1583 ? names.fromString(bounds.toString())
1584 : names.empty,
1585 syms.noSymbol);
1586 if (bounds.head.tag == TYPEVAR)
1587 // error condition, recover
1588 bc.erasure_field = syms.objectType;
1589 else
1590 bc.erasure_field = erasure(bounds.head);
1591 bc.members_field = new Scope(bc);
1592 ClassType bt = (ClassType)bc.type;
1593 bt.allparams_field = List.nil();
1594 if (supertype != null) {
1595 bt.supertype_field = supertype;
1596 bt.interfaces_field = bounds;
1597 } else {
1598 bt.supertype_field = bounds.head;
1599 bt.interfaces_field = bounds.tail;
1600 }
1601 assert bt.supertype_field.tsym.completer != null
1602 || !bt.supertype_field.isInterface()
1603 : bt.supertype_field;
1604 return bt;
1605 }
1607 /**
1608 * Same as {@link #makeCompoundType(List,Type)}, except that the
1609 * second parameter is computed directly. Note that this might
1610 * cause a symbol completion. Hence, this version of
1611 * makeCompoundType may not be called during a classfile read.
1612 */
1613 public Type makeCompoundType(List<Type> bounds) {
1614 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1615 supertype(bounds.head) : null;
1616 return makeCompoundType(bounds, supertype);
1617 }
1619 /**
1620 * A convenience wrapper for {@link #makeCompoundType(List)}; the
1621 * arguments are converted to a list and passed to the other
1622 * method. Note that this might cause a symbol completion.
1623 * Hence, this version of makeCompoundType may not be called
1624 * during a classfile read.
1625 */
1626 public Type makeCompoundType(Type bound1, Type bound2) {
1627 return makeCompoundType(List.of(bound1, bound2));
1628 }
1629 // </editor-fold>
1631 // <editor-fold defaultstate="collapsed" desc="supertype">
1632 public Type supertype(Type t) {
1633 return supertype.visit(t);
1634 }
1635 // where
1636 private UnaryVisitor<Type> supertype = new UnaryVisitor<Type>() {
1638 public Type visitType(Type t, Void ignored) {
1639 // A note on wildcards: there is no good way to
1640 // determine a supertype for a super bounded wildcard.
1641 return null;
1642 }
1644 @Override
1645 public Type visitClassType(ClassType t, Void ignored) {
1646 if (t.supertype_field == null) {
1647 Type supertype = ((ClassSymbol)t.tsym).getSuperclass();
1648 // An interface has no superclass; its supertype is Object.
1649 if (t.isInterface())
1650 supertype = ((ClassType)t.tsym.type).supertype_field;
1651 if (t.supertype_field == null) {
1652 List<Type> actuals = classBound(t).allparams();
1653 List<Type> formals = t.tsym.type.allparams();
1654 if (t.hasErasedSupertypes()) {
1655 t.supertype_field = erasureRecursive(supertype);
1656 } else if (formals.nonEmpty()) {
1657 t.supertype_field = subst(supertype, formals, actuals);
1658 }
1659 else {
1660 t.supertype_field = supertype;
1661 }
1662 }
1663 }
1664 return t.supertype_field;
1665 }
1667 /**
1668 * The supertype is always a class type. If the type
1669 * variable's bounds start with a class type, this is also
1670 * the supertype. Otherwise, the supertype is
1671 * java.lang.Object.
1672 */
1673 @Override
1674 public Type visitTypeVar(TypeVar t, Void ignored) {
1675 if (t.bound.tag == TYPEVAR ||
1676 (!t.bound.isCompound() && !t.bound.isInterface())) {
1677 return t.bound;
1678 } else {
1679 return supertype(t.bound);
1680 }
1681 }
1683 @Override
1684 public Type visitArrayType(ArrayType t, Void ignored) {
1685 if (t.elemtype.isPrimitive() || isSameType(t.elemtype, syms.objectType))
1686 return arraySuperType();
1687 else
1688 return new ArrayType(supertype(t.elemtype), t.tsym);
1689 }
1691 @Override
1692 public Type visitErrorType(ErrorType t, Void ignored) {
1693 return t;
1694 }
1695 };
1696 // </editor-fold>
1698 // <editor-fold defaultstate="collapsed" desc="interfaces">
1699 /**
1700 * Return the interfaces implemented by this class.
1701 */
1702 public List<Type> interfaces(Type t) {
1703 return interfaces.visit(t);
1704 }
1705 // where
1706 private UnaryVisitor<List<Type>> interfaces = new UnaryVisitor<List<Type>>() {
1708 public List<Type> visitType(Type t, Void ignored) {
1709 return List.nil();
1710 }
1712 @Override
1713 public List<Type> visitClassType(ClassType t, Void ignored) {
1714 if (t.interfaces_field == null) {
1715 List<Type> interfaces = ((ClassSymbol)t.tsym).getInterfaces();
1716 if (t.interfaces_field == null) {
1717 // If t.interfaces_field is null, then t must
1718 // be a parameterized type (not to be confused
1719 // with a generic type declaration).
1720 // Terminology:
1721 // Parameterized type: List<String>
1722 // Generic type declaration: class List<E> { ... }
1723 // So t corresponds to List<String> and
1724 // t.tsym.type corresponds to List<E>.
1725 // The reason t must be parameterized type is
1726 // that completion will happen as a side
1727 // effect of calling
1728 // ClassSymbol.getInterfaces. Since
1729 // t.interfaces_field is null after
1730 // completion, we can assume that t is not the
1731 // type of a class/interface declaration.
1732 assert t != t.tsym.type : t.toString();
1733 List<Type> actuals = t.allparams();
1734 List<Type> formals = t.tsym.type.allparams();
1735 if (t.hasErasedSupertypes()) {
1736 t.interfaces_field = erasureRecursive(interfaces);
1737 } else if (formals.nonEmpty()) {
1738 t.interfaces_field =
1739 upperBounds(subst(interfaces, formals, actuals));
1740 }
1741 else {
1742 t.interfaces_field = interfaces;
1743 }
1744 }
1745 }
1746 return t.interfaces_field;
1747 }
1749 @Override
1750 public List<Type> visitTypeVar(TypeVar t, Void ignored) {
1751 if (t.bound.isCompound())
1752 return interfaces(t.bound);
1754 if (t.bound.isInterface())
1755 return List.of(t.bound);
1757 return List.nil();
1758 }
1759 };
1760 // </editor-fold>
1762 // <editor-fold defaultstate="collapsed" desc="isDerivedRaw">
1763 Map<Type,Boolean> isDerivedRawCache = new HashMap<Type,Boolean>();
1765 public boolean isDerivedRaw(Type t) {
1766 Boolean result = isDerivedRawCache.get(t);
1767 if (result == null) {
1768 result = isDerivedRawInternal(t);
1769 isDerivedRawCache.put(t, result);
1770 }
1771 return result;
1772 }
1774 public boolean isDerivedRawInternal(Type t) {
1775 if (t.isErroneous())
1776 return false;
1777 return
1778 t.isRaw() ||
1779 supertype(t) != null && isDerivedRaw(supertype(t)) ||
1780 isDerivedRaw(interfaces(t));
1781 }
1783 public boolean isDerivedRaw(List<Type> ts) {
1784 List<Type> l = ts;
1785 while (l.nonEmpty() && !isDerivedRaw(l.head)) l = l.tail;
1786 return l.nonEmpty();
1787 }
1788 // </editor-fold>
1790 // <editor-fold defaultstate="collapsed" desc="setBounds">
1791 /**
1792 * Set the bounds field of the given type variable to reflect a
1793 * (possibly multiple) list of bounds.
1794 * @param t a type variable
1795 * @param bounds the bounds, must be nonempty
1796 * @param supertype is objectType if all bounds are interfaces,
1797 * null otherwise.
1798 */
1799 public void setBounds(TypeVar t, List<Type> bounds, Type supertype) {
1800 if (bounds.tail.isEmpty())
1801 t.bound = bounds.head;
1802 else
1803 t.bound = makeCompoundType(bounds, supertype);
1804 t.rank_field = -1;
1805 }
1807 /**
1808 * Same as {@link #setBounds(Type.TypeVar,List,Type)}, except that
1809 * third parameter is computed directly. Note that this test
1810 * might cause a symbol completion. Hence, this version of
1811 * setBounds may not be called during a classfile read.
1812 */
1813 public void setBounds(TypeVar t, List<Type> bounds) {
1814 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1815 supertype(bounds.head) : null;
1816 setBounds(t, bounds, supertype);
1817 t.rank_field = -1;
1818 }
1819 // </editor-fold>
1821 // <editor-fold defaultstate="collapsed" desc="getBounds">
1822 /**
1823 * Return list of bounds of the given type variable.
1824 */
1825 public List<Type> getBounds(TypeVar t) {
1826 if (t.bound.isErroneous() || !t.bound.isCompound())
1827 return List.of(t.bound);
1828 else if ((erasure(t).tsym.flags() & INTERFACE) == 0)
1829 return interfaces(t).prepend(supertype(t));
1830 else
1831 // No superclass was given in bounds.
1832 // In this case, supertype is Object, erasure is first interface.
1833 return interfaces(t);
1834 }
1835 // </editor-fold>
1837 // <editor-fold defaultstate="collapsed" desc="classBound">
1838 /**
1839 * If the given type is a (possibly selected) type variable,
1840 * return the bounding class of this type, otherwise return the
1841 * type itself.
1842 */
1843 public Type classBound(Type t) {
1844 return classBound.visit(t);
1845 }
1846 // where
1847 private UnaryVisitor<Type> classBound = new UnaryVisitor<Type>() {
1849 public Type visitType(Type t, Void ignored) {
1850 return t;
1851 }
1853 @Override
1854 public Type visitClassType(ClassType t, Void ignored) {
1855 Type outer1 = classBound(t.getEnclosingType());
1856 if (outer1 != t.getEnclosingType())
1857 return new ClassType(outer1, t.getTypeArguments(), t.tsym);
1858 else
1859 return t;
1860 }
1862 @Override
1863 public Type visitTypeVar(TypeVar t, Void ignored) {
1864 return classBound(supertype(t));
1865 }
1867 @Override
1868 public Type visitErrorType(ErrorType t, Void ignored) {
1869 return t;
1870 }
1871 };
1872 // </editor-fold>
1874 // <editor-fold defaultstate="collapsed" desc="sub signature / override equivalence">
1875 /**
1876 * Returns true iff the first signature is a <em>sub
1877 * signature</em> of the other. This is <b>not</b> an equivalence
1878 * relation.
1879 *
1880 * @see "The Java Language Specification, Third Ed. (8.4.2)."
1881 * @see #overrideEquivalent(Type t, Type s)
1882 * @param t first signature (possibly raw).
1883 * @param s second signature (could be subjected to erasure).
1884 * @return true if t is a sub signature of s.
1885 */
1886 public boolean isSubSignature(Type t, Type s) {
1887 return hasSameArgs(t, s) || hasSameArgs(t, erasure(s));
1888 }
1890 /**
1891 * Returns true iff these signatures are related by <em>override
1892 * equivalence</em>. This is the natural extension of
1893 * isSubSignature to an equivalence relation.
1894 *
1895 * @see "The Java Language Specification, Third Ed. (8.4.2)."
1896 * @see #isSubSignature(Type t, Type s)
1897 * @param t a signature (possible raw, could be subjected to
1898 * erasure).
1899 * @param s a signature (possible raw, could be subjected to
1900 * erasure).
1901 * @return true if either argument is a sub signature of the other.
1902 */
1903 public boolean overrideEquivalent(Type t, Type s) {
1904 return hasSameArgs(t, s) ||
1905 hasSameArgs(t, erasure(s)) || hasSameArgs(erasure(t), s);
1906 }
1908 /**
1909 * Does t have the same arguments as s? It is assumed that both
1910 * types are (possibly polymorphic) method types. Monomorphic
1911 * method types "have the same arguments", if their argument lists
1912 * are equal. Polymorphic method types "have the same arguments",
1913 * if they have the same arguments after renaming all type
1914 * variables of one to corresponding type variables in the other,
1915 * where correspondence is by position in the type parameter list.
1916 */
1917 public boolean hasSameArgs(Type t, Type s) {
1918 return hasSameArgs.visit(t, s);
1919 }
1920 // where
1921 private TypeRelation hasSameArgs = new TypeRelation() {
1923 public Boolean visitType(Type t, Type s) {
1924 throw new AssertionError();
1925 }
1927 @Override
1928 public Boolean visitMethodType(MethodType t, Type s) {
1929 return s.tag == METHOD
1930 && containsTypeEquivalent(t.argtypes, s.getParameterTypes());
1931 }
1933 @Override
1934 public Boolean visitForAll(ForAll t, Type s) {
1935 if (s.tag != FORALL)
1936 return false;
1938 ForAll forAll = (ForAll)s;
1939 return hasSameBounds(t, forAll)
1940 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
1941 }
1943 @Override
1944 public Boolean visitErrorType(ErrorType t, Type s) {
1945 return false;
1946 }
1947 };
1948 // </editor-fold>
1950 // <editor-fold defaultstate="collapsed" desc="subst">
1951 public List<Type> subst(List<Type> ts,
1952 List<Type> from,
1953 List<Type> to) {
1954 return new Subst(from, to).subst(ts);
1955 }
1957 /**
1958 * Substitute all occurrences of a type in `from' with the
1959 * corresponding type in `to' in 't'. Match lists `from' and `to'
1960 * from the right: If lists have different length, discard leading
1961 * elements of the longer list.
1962 */
1963 public Type subst(Type t, List<Type> from, List<Type> to) {
1964 return new Subst(from, to).subst(t);
1965 }
1967 private class Subst extends UnaryVisitor<Type> {
1968 List<Type> from;
1969 List<Type> to;
1971 public Subst(List<Type> from, List<Type> to) {
1972 int fromLength = from.length();
1973 int toLength = to.length();
1974 while (fromLength > toLength) {
1975 fromLength--;
1976 from = from.tail;
1977 }
1978 while (fromLength < toLength) {
1979 toLength--;
1980 to = to.tail;
1981 }
1982 this.from = from;
1983 this.to = to;
1984 }
1986 Type subst(Type t) {
1987 if (from.tail == null)
1988 return t;
1989 else
1990 return visit(t);
1991 }
1993 List<Type> subst(List<Type> ts) {
1994 if (from.tail == null)
1995 return ts;
1996 boolean wild = false;
1997 if (ts.nonEmpty() && from.nonEmpty()) {
1998 Type head1 = subst(ts.head);
1999 List<Type> tail1 = subst(ts.tail);
2000 if (head1 != ts.head || tail1 != ts.tail)
2001 return tail1.prepend(head1);
2002 }
2003 return ts;
2004 }
2006 public Type visitType(Type t, Void ignored) {
2007 return t;
2008 }
2010 @Override
2011 public Type visitMethodType(MethodType t, Void ignored) {
2012 List<Type> argtypes = subst(t.argtypes);
2013 Type restype = subst(t.restype);
2014 List<Type> thrown = subst(t.thrown);
2015 if (argtypes == t.argtypes &&
2016 restype == t.restype &&
2017 thrown == t.thrown)
2018 return t;
2019 else
2020 return new MethodType(argtypes, restype, thrown, t.tsym);
2021 }
2023 @Override
2024 public Type visitTypeVar(TypeVar t, Void ignored) {
2025 for (List<Type> from = this.from, to = this.to;
2026 from.nonEmpty();
2027 from = from.tail, to = to.tail) {
2028 if (t == from.head) {
2029 return to.head.withTypeVar(t);
2030 }
2031 }
2032 return t;
2033 }
2035 @Override
2036 public Type visitClassType(ClassType t, Void ignored) {
2037 if (!t.isCompound()) {
2038 List<Type> typarams = t.getTypeArguments();
2039 List<Type> typarams1 = subst(typarams);
2040 Type outer = t.getEnclosingType();
2041 Type outer1 = subst(outer);
2042 if (typarams1 == typarams && outer1 == outer)
2043 return t;
2044 else
2045 return new ClassType(outer1, typarams1, t.tsym);
2046 } else {
2047 Type st = subst(supertype(t));
2048 List<Type> is = upperBounds(subst(interfaces(t)));
2049 if (st == supertype(t) && is == interfaces(t))
2050 return t;
2051 else
2052 return makeCompoundType(is.prepend(st));
2053 }
2054 }
2056 @Override
2057 public Type visitWildcardType(WildcardType t, Void ignored) {
2058 Type bound = t.type;
2059 if (t.kind != BoundKind.UNBOUND)
2060 bound = subst(bound);
2061 if (bound == t.type) {
2062 return t;
2063 } else {
2064 if (t.isExtendsBound() && bound.isExtendsBound())
2065 bound = upperBound(bound);
2066 return new WildcardType(bound, t.kind, syms.boundClass, t.bound);
2067 }
2068 }
2070 @Override
2071 public Type visitArrayType(ArrayType t, Void ignored) {
2072 Type elemtype = subst(t.elemtype);
2073 if (elemtype == t.elemtype)
2074 return t;
2075 else
2076 return new ArrayType(upperBound(elemtype), t.tsym);
2077 }
2079 @Override
2080 public Type visitForAll(ForAll t, Void ignored) {
2081 List<Type> tvars1 = substBounds(t.tvars, from, to);
2082 Type qtype1 = subst(t.qtype);
2083 if (tvars1 == t.tvars && qtype1 == t.qtype) {
2084 return t;
2085 } else if (tvars1 == t.tvars) {
2086 return new ForAll(tvars1, qtype1);
2087 } else {
2088 return new ForAll(tvars1, Types.this.subst(qtype1, t.tvars, tvars1));
2089 }
2090 }
2092 @Override
2093 public Type visitErrorType(ErrorType t, Void ignored) {
2094 return t;
2095 }
2096 }
2098 public List<Type> substBounds(List<Type> tvars,
2099 List<Type> from,
2100 List<Type> to) {
2101 if (tvars.isEmpty())
2102 return tvars;
2103 if (tvars.tail.isEmpty())
2104 // fast common case
2105 return List.<Type>of(substBound((TypeVar)tvars.head, from, to));
2106 ListBuffer<Type> newBoundsBuf = lb();
2107 boolean changed = false;
2108 // calculate new bounds
2109 for (Type t : tvars) {
2110 TypeVar tv = (TypeVar) t;
2111 Type bound = subst(tv.bound, from, to);
2112 if (bound != tv.bound)
2113 changed = true;
2114 newBoundsBuf.append(bound);
2115 }
2116 if (!changed)
2117 return tvars;
2118 ListBuffer<Type> newTvars = lb();
2119 // create new type variables without bounds
2120 for (Type t : tvars) {
2121 newTvars.append(new TypeVar(t.tsym, null, syms.botType));
2122 }
2123 // the new bounds should use the new type variables in place
2124 // of the old
2125 List<Type> newBounds = newBoundsBuf.toList();
2126 from = tvars;
2127 to = newTvars.toList();
2128 for (; !newBounds.isEmpty(); newBounds = newBounds.tail) {
2129 newBounds.head = subst(newBounds.head, from, to);
2130 }
2131 newBounds = newBoundsBuf.toList();
2132 // set the bounds of new type variables to the new bounds
2133 for (Type t : newTvars.toList()) {
2134 TypeVar tv = (TypeVar) t;
2135 tv.bound = newBounds.head;
2136 newBounds = newBounds.tail;
2137 }
2138 return newTvars.toList();
2139 }
2141 public TypeVar substBound(TypeVar t, List<Type> from, List<Type> to) {
2142 Type bound1 = subst(t.bound, from, to);
2143 if (bound1 == t.bound)
2144 return t;
2145 else
2146 return new TypeVar(t.tsym, bound1, syms.botType);
2147 }
2148 // </editor-fold>
2150 // <editor-fold defaultstate="collapsed" desc="hasSameBounds">
2151 /**
2152 * Does t have the same bounds for quantified variables as s?
2153 */
2154 boolean hasSameBounds(ForAll t, ForAll s) {
2155 List<Type> l1 = t.tvars;
2156 List<Type> l2 = s.tvars;
2157 while (l1.nonEmpty() && l2.nonEmpty() &&
2158 isSameType(l1.head.getUpperBound(),
2159 subst(l2.head.getUpperBound(),
2160 s.tvars,
2161 t.tvars))) {
2162 l1 = l1.tail;
2163 l2 = l2.tail;
2164 }
2165 return l1.isEmpty() && l2.isEmpty();
2166 }
2167 // </editor-fold>
2169 // <editor-fold defaultstate="collapsed" desc="newInstances">
2170 /** Create new vector of type variables from list of variables
2171 * changing all recursive bounds from old to new list.
2172 */
2173 public List<Type> newInstances(List<Type> tvars) {
2174 List<Type> tvars1 = Type.map(tvars, newInstanceFun);
2175 for (List<Type> l = tvars1; l.nonEmpty(); l = l.tail) {
2176 TypeVar tv = (TypeVar) l.head;
2177 tv.bound = subst(tv.bound, tvars, tvars1);
2178 }
2179 return tvars1;
2180 }
2181 static private Mapping newInstanceFun = new Mapping("newInstanceFun") {
2182 public Type apply(Type t) { return new TypeVar(t.tsym, t.getUpperBound(), t.getLowerBound()); }
2183 };
2184 // </editor-fold>
2186 // <editor-fold defaultstate="collapsed" desc="rank">
2187 /**
2188 * The rank of a class is the length of the longest path between
2189 * the class and java.lang.Object in the class inheritance
2190 * graph. Undefined for all but reference types.
2191 */
2192 public int rank(Type t) {
2193 switch(t.tag) {
2194 case CLASS: {
2195 ClassType cls = (ClassType)t;
2196 if (cls.rank_field < 0) {
2197 Name fullname = cls.tsym.getQualifiedName();
2198 if (fullname == fullname.table.java_lang_Object)
2199 cls.rank_field = 0;
2200 else {
2201 int r = rank(supertype(cls));
2202 for (List<Type> l = interfaces(cls);
2203 l.nonEmpty();
2204 l = l.tail) {
2205 if (rank(l.head) > r)
2206 r = rank(l.head);
2207 }
2208 cls.rank_field = r + 1;
2209 }
2210 }
2211 return cls.rank_field;
2212 }
2213 case TYPEVAR: {
2214 TypeVar tvar = (TypeVar)t;
2215 if (tvar.rank_field < 0) {
2216 int r = rank(supertype(tvar));
2217 for (List<Type> l = interfaces(tvar);
2218 l.nonEmpty();
2219 l = l.tail) {
2220 if (rank(l.head) > r) r = rank(l.head);
2221 }
2222 tvar.rank_field = r + 1;
2223 }
2224 return tvar.rank_field;
2225 }
2226 case ERROR:
2227 return 0;
2228 default:
2229 throw new AssertionError();
2230 }
2231 }
2232 // </editor-fold>
2234 // <editor-fold defaultstate="collapsed" desc="toString">
2235 /**
2236 * This toString is slightly more descriptive than the one on Type.
2237 */
2238 public String toString(Type t) {
2239 if (t.tag == FORALL) {
2240 ForAll forAll = (ForAll)t;
2241 return typaramsString(forAll.tvars) + forAll.qtype;
2242 }
2243 return "" + t;
2244 }
2245 // where
2246 private String typaramsString(List<Type> tvars) {
2247 StringBuffer s = new StringBuffer();
2248 s.append('<');
2249 boolean first = true;
2250 for (Type t : tvars) {
2251 if (!first) s.append(", ");
2252 first = false;
2253 appendTyparamString(((TypeVar)t), s);
2254 }
2255 s.append('>');
2256 return s.toString();
2257 }
2258 private void appendTyparamString(TypeVar t, StringBuffer buf) {
2259 buf.append(t);
2260 if (t.bound == null ||
2261 t.bound.tsym.getQualifiedName() == names.java_lang_Object)
2262 return;
2263 buf.append(" extends "); // Java syntax; no need for i18n
2264 Type bound = t.bound;
2265 if (!bound.isCompound()) {
2266 buf.append(bound);
2267 } else if ((erasure(t).tsym.flags() & INTERFACE) == 0) {
2268 buf.append(supertype(t));
2269 for (Type intf : interfaces(t)) {
2270 buf.append('&');
2271 buf.append(intf);
2272 }
2273 } else {
2274 // No superclass was given in bounds.
2275 // In this case, supertype is Object, erasure is first interface.
2276 boolean first = true;
2277 for (Type intf : interfaces(t)) {
2278 if (!first) buf.append('&');
2279 first = false;
2280 buf.append(intf);
2281 }
2282 }
2283 }
2284 // </editor-fold>
2286 // <editor-fold defaultstate="collapsed" desc="Determining least upper bounds of types">
2287 /**
2288 * A cache for closures.
2289 *
2290 * <p>A closure is a list of all the supertypes and interfaces of
2291 * a class or interface type, ordered by ClassSymbol.precedes
2292 * (that is, subclasses come first, arbitrary but fixed
2293 * otherwise).
2294 */
2295 private Map<Type,List<Type>> closureCache = new HashMap<Type,List<Type>>();
2297 /**
2298 * Returns the closure of a class or interface type.
2299 */
2300 public List<Type> closure(Type t) {
2301 List<Type> cl = closureCache.get(t);
2302 if (cl == null) {
2303 Type st = supertype(t);
2304 if (!t.isCompound()) {
2305 if (st.tag == CLASS) {
2306 cl = insert(closure(st), t);
2307 } else if (st.tag == TYPEVAR) {
2308 cl = closure(st).prepend(t);
2309 } else {
2310 cl = List.of(t);
2311 }
2312 } else {
2313 cl = closure(supertype(t));
2314 }
2315 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail)
2316 cl = union(cl, closure(l.head));
2317 closureCache.put(t, cl);
2318 }
2319 return cl;
2320 }
2322 /**
2323 * Insert a type in a closure
2324 */
2325 public List<Type> insert(List<Type> cl, Type t) {
2326 if (cl.isEmpty() || t.tsym.precedes(cl.head.tsym, this)) {
2327 return cl.prepend(t);
2328 } else if (cl.head.tsym.precedes(t.tsym, this)) {
2329 return insert(cl.tail, t).prepend(cl.head);
2330 } else {
2331 return cl;
2332 }
2333 }
2335 /**
2336 * Form the union of two closures
2337 */
2338 public List<Type> union(List<Type> cl1, List<Type> cl2) {
2339 if (cl1.isEmpty()) {
2340 return cl2;
2341 } else if (cl2.isEmpty()) {
2342 return cl1;
2343 } else if (cl1.head.tsym.precedes(cl2.head.tsym, this)) {
2344 return union(cl1.tail, cl2).prepend(cl1.head);
2345 } else if (cl2.head.tsym.precedes(cl1.head.tsym, this)) {
2346 return union(cl1, cl2.tail).prepend(cl2.head);
2347 } else {
2348 return union(cl1.tail, cl2.tail).prepend(cl1.head);
2349 }
2350 }
2352 /**
2353 * Intersect two closures
2354 */
2355 public List<Type> intersect(List<Type> cl1, List<Type> cl2) {
2356 if (cl1 == cl2)
2357 return cl1;
2358 if (cl1.isEmpty() || cl2.isEmpty())
2359 return List.nil();
2360 if (cl1.head.tsym.precedes(cl2.head.tsym, this))
2361 return intersect(cl1.tail, cl2);
2362 if (cl2.head.tsym.precedes(cl1.head.tsym, this))
2363 return intersect(cl1, cl2.tail);
2364 if (isSameType(cl1.head, cl2.head))
2365 return intersect(cl1.tail, cl2.tail).prepend(cl1.head);
2366 if (cl1.head.tsym == cl2.head.tsym &&
2367 cl1.head.tag == CLASS && cl2.head.tag == CLASS) {
2368 if (cl1.head.isParameterized() && cl2.head.isParameterized()) {
2369 Type merge = merge(cl1.head,cl2.head);
2370 return intersect(cl1.tail, cl2.tail).prepend(merge);
2371 }
2372 if (cl1.head.isRaw() || cl2.head.isRaw())
2373 return intersect(cl1.tail, cl2.tail).prepend(erasure(cl1.head));
2374 }
2375 return intersect(cl1.tail, cl2.tail);
2376 }
2377 // where
2378 class TypePair {
2379 final Type t1;
2380 final Type t2;
2381 TypePair(Type t1, Type t2) {
2382 this.t1 = t1;
2383 this.t2 = t2;
2384 }
2385 @Override
2386 public int hashCode() {
2387 return 127 * Types.this.hashCode(t1) + Types.this.hashCode(t2);
2388 }
2389 @Override
2390 public boolean equals(Object obj) {
2391 if (!(obj instanceof TypePair))
2392 return false;
2393 TypePair typePair = (TypePair)obj;
2394 return isSameType(t1, typePair.t1)
2395 && isSameType(t2, typePair.t2);
2396 }
2397 }
2398 Set<TypePair> mergeCache = new HashSet<TypePair>();
2399 private Type merge(Type c1, Type c2) {
2400 ClassType class1 = (ClassType) c1;
2401 List<Type> act1 = class1.getTypeArguments();
2402 ClassType class2 = (ClassType) c2;
2403 List<Type> act2 = class2.getTypeArguments();
2404 ListBuffer<Type> merged = new ListBuffer<Type>();
2405 List<Type> typarams = class1.tsym.type.getTypeArguments();
2407 while (act1.nonEmpty() && act2.nonEmpty() && typarams.nonEmpty()) {
2408 if (containsType(act1.head, act2.head)) {
2409 merged.append(act1.head);
2410 } else if (containsType(act2.head, act1.head)) {
2411 merged.append(act2.head);
2412 } else {
2413 TypePair pair = new TypePair(c1, c2);
2414 Type m;
2415 if (mergeCache.add(pair)) {
2416 m = new WildcardType(lub(upperBound(act1.head),
2417 upperBound(act2.head)),
2418 BoundKind.EXTENDS,
2419 syms.boundClass);
2420 mergeCache.remove(pair);
2421 } else {
2422 m = new WildcardType(syms.objectType,
2423 BoundKind.UNBOUND,
2424 syms.boundClass);
2425 }
2426 merged.append(m.withTypeVar(typarams.head));
2427 }
2428 act1 = act1.tail;
2429 act2 = act2.tail;
2430 typarams = typarams.tail;
2431 }
2432 assert(act1.isEmpty() && act2.isEmpty() && typarams.isEmpty());
2433 return new ClassType(class1.getEnclosingType(), merged.toList(), class1.tsym);
2434 }
2436 /**
2437 * Return the minimum type of a closure, a compound type if no
2438 * unique minimum exists.
2439 */
2440 private Type compoundMin(List<Type> cl) {
2441 if (cl.isEmpty()) return syms.objectType;
2442 List<Type> compound = closureMin(cl);
2443 if (compound.isEmpty())
2444 return null;
2445 else if (compound.tail.isEmpty())
2446 return compound.head;
2447 else
2448 return makeCompoundType(compound);
2449 }
2451 /**
2452 * Return the minimum types of a closure, suitable for computing
2453 * compoundMin or glb.
2454 */
2455 private List<Type> closureMin(List<Type> cl) {
2456 ListBuffer<Type> classes = lb();
2457 ListBuffer<Type> interfaces = lb();
2458 while (!cl.isEmpty()) {
2459 Type current = cl.head;
2460 if (current.isInterface())
2461 interfaces.append(current);
2462 else
2463 classes.append(current);
2464 ListBuffer<Type> candidates = lb();
2465 for (Type t : cl.tail) {
2466 if (!isSubtypeNoCapture(current, t))
2467 candidates.append(t);
2468 }
2469 cl = candidates.toList();
2470 }
2471 return classes.appendList(interfaces).toList();
2472 }
2474 /**
2475 * Return the least upper bound of pair of types. if the lub does
2476 * not exist return null.
2477 */
2478 public Type lub(Type t1, Type t2) {
2479 return lub(List.of(t1, t2));
2480 }
2482 /**
2483 * Return the least upper bound (lub) of set of types. If the lub
2484 * does not exist return the type of null (bottom).
2485 */
2486 public Type lub(List<Type> ts) {
2487 final int ARRAY_BOUND = 1;
2488 final int CLASS_BOUND = 2;
2489 int boundkind = 0;
2490 for (Type t : ts) {
2491 switch (t.tag) {
2492 case CLASS:
2493 boundkind |= CLASS_BOUND;
2494 break;
2495 case ARRAY:
2496 boundkind |= ARRAY_BOUND;
2497 break;
2498 case TYPEVAR:
2499 do {
2500 t = t.getUpperBound();
2501 } while (t.tag == TYPEVAR);
2502 if (t.tag == ARRAY) {
2503 boundkind |= ARRAY_BOUND;
2504 } else {
2505 boundkind |= CLASS_BOUND;
2506 }
2507 break;
2508 default:
2509 if (t.isPrimitive())
2510 return syms.errType;
2511 }
2512 }
2513 switch (boundkind) {
2514 case 0:
2515 return syms.botType;
2517 case ARRAY_BOUND:
2518 // calculate lub(A[], B[])
2519 List<Type> elements = Type.map(ts, elemTypeFun);
2520 for (Type t : elements) {
2521 if (t.isPrimitive()) {
2522 // if a primitive type is found, then return
2523 // arraySuperType unless all the types are the
2524 // same
2525 Type first = ts.head;
2526 for (Type s : ts.tail) {
2527 if (!isSameType(first, s)) {
2528 // lub(int[], B[]) is Cloneable & Serializable
2529 return arraySuperType();
2530 }
2531 }
2532 // all the array types are the same, return one
2533 // lub(int[], int[]) is int[]
2534 return first;
2535 }
2536 }
2537 // lub(A[], B[]) is lub(A, B)[]
2538 return new ArrayType(lub(elements), syms.arrayClass);
2540 case CLASS_BOUND:
2541 // calculate lub(A, B)
2542 while (ts.head.tag != CLASS && ts.head.tag != TYPEVAR)
2543 ts = ts.tail;
2544 assert !ts.isEmpty();
2545 List<Type> cl = closure(ts.head);
2546 for (Type t : ts.tail) {
2547 if (t.tag == CLASS || t.tag == TYPEVAR)
2548 cl = intersect(cl, closure(t));
2549 }
2550 return compoundMin(cl);
2552 default:
2553 // calculate lub(A, B[])
2554 List<Type> classes = List.of(arraySuperType());
2555 for (Type t : ts) {
2556 if (t.tag != ARRAY) // Filter out any arrays
2557 classes = classes.prepend(t);
2558 }
2559 // lub(A, B[]) is lub(A, arraySuperType)
2560 return lub(classes);
2561 }
2562 }
2563 // where
2564 private Type arraySuperType = null;
2565 private Type arraySuperType() {
2566 // initialized lazily to avoid problems during compiler startup
2567 if (arraySuperType == null) {
2568 synchronized (this) {
2569 if (arraySuperType == null) {
2570 // JLS 10.8: all arrays implement Cloneable and Serializable.
2571 arraySuperType = makeCompoundType(List.of(syms.serializableType,
2572 syms.cloneableType),
2573 syms.objectType);
2574 }
2575 }
2576 }
2577 return arraySuperType;
2578 }
2579 // </editor-fold>
2581 // <editor-fold defaultstate="collapsed" desc="Greatest lower bound">
2582 public Type glb(Type t, Type s) {
2583 if (s == null)
2584 return t;
2585 else if (isSubtypeNoCapture(t, s))
2586 return t;
2587 else if (isSubtypeNoCapture(s, t))
2588 return s;
2590 List<Type> closure = union(closure(t), closure(s));
2591 List<Type> bounds = closureMin(closure);
2593 if (bounds.isEmpty()) { // length == 0
2594 return syms.objectType;
2595 } else if (bounds.tail.isEmpty()) { // length == 1
2596 return bounds.head;
2597 } else { // length > 1
2598 int classCount = 0;
2599 for (Type bound : bounds)
2600 if (!bound.isInterface())
2601 classCount++;
2602 if (classCount > 1)
2603 return syms.errType;
2604 }
2605 return makeCompoundType(bounds);
2606 }
2607 // </editor-fold>
2609 // <editor-fold defaultstate="collapsed" desc="hashCode">
2610 /**
2611 * Compute a hash code on a type.
2612 */
2613 public static int hashCode(Type t) {
2614 return hashCode.visit(t);
2615 }
2616 // where
2617 private static final UnaryVisitor<Integer> hashCode = new UnaryVisitor<Integer>() {
2619 public Integer visitType(Type t, Void ignored) {
2620 return t.tag;
2621 }
2623 @Override
2624 public Integer visitClassType(ClassType t, Void ignored) {
2625 int result = visit(t.getEnclosingType());
2626 result *= 127;
2627 result += t.tsym.flatName().hashCode();
2628 for (Type s : t.getTypeArguments()) {
2629 result *= 127;
2630 result += visit(s);
2631 }
2632 return result;
2633 }
2635 @Override
2636 public Integer visitWildcardType(WildcardType t, Void ignored) {
2637 int result = t.kind.hashCode();
2638 if (t.type != null) {
2639 result *= 127;
2640 result += visit(t.type);
2641 }
2642 return result;
2643 }
2645 @Override
2646 public Integer visitArrayType(ArrayType t, Void ignored) {
2647 return visit(t.elemtype) + 12;
2648 }
2650 @Override
2651 public Integer visitTypeVar(TypeVar t, Void ignored) {
2652 return System.identityHashCode(t.tsym);
2653 }
2655 @Override
2656 public Integer visitUndetVar(UndetVar t, Void ignored) {
2657 return System.identityHashCode(t);
2658 }
2660 @Override
2661 public Integer visitErrorType(ErrorType t, Void ignored) {
2662 return 0;
2663 }
2664 };
2665 // </editor-fold>
2667 // <editor-fold defaultstate="collapsed" desc="Return-Type-Substitutable">
2668 /**
2669 * Does t have a result that is a subtype of the result type of s,
2670 * suitable for covariant returns? It is assumed that both types
2671 * are (possibly polymorphic) method types. Monomorphic method
2672 * types are handled in the obvious way. Polymorphic method types
2673 * require renaming all type variables of one to corresponding
2674 * type variables in the other, where correspondence is by
2675 * position in the type parameter list. */
2676 public boolean resultSubtype(Type t, Type s, Warner warner) {
2677 List<Type> tvars = t.getTypeArguments();
2678 List<Type> svars = s.getTypeArguments();
2679 Type tres = t.getReturnType();
2680 Type sres = subst(s.getReturnType(), svars, tvars);
2681 return covariantReturnType(tres, sres, warner);
2682 }
2684 /**
2685 * Return-Type-Substitutable.
2686 * @see <a href="http://java.sun.com/docs/books/jls/">The Java
2687 * Language Specification, Third Ed. (8.4.5)</a>
2688 */
2689 public boolean returnTypeSubstitutable(Type r1, Type r2) {
2690 if (hasSameArgs(r1, r2))
2691 return resultSubtype(r1, r2, Warner.noWarnings);
2692 else
2693 return covariantReturnType(r1.getReturnType(),
2694 erasure(r2.getReturnType()),
2695 Warner.noWarnings);
2696 }
2698 public boolean returnTypeSubstitutable(Type r1,
2699 Type r2, Type r2res,
2700 Warner warner) {
2701 if (isSameType(r1.getReturnType(), r2res))
2702 return true;
2703 if (r1.getReturnType().isPrimitive() || r2res.isPrimitive())
2704 return false;
2706 if (hasSameArgs(r1, r2))
2707 return covariantReturnType(r1.getReturnType(), r2res, warner);
2708 if (!source.allowCovariantReturns())
2709 return false;
2710 if (isSubtypeUnchecked(r1.getReturnType(), r2res, warner))
2711 return true;
2712 if (!isSubtype(r1.getReturnType(), erasure(r2res)))
2713 return false;
2714 warner.warnUnchecked();
2715 return true;
2716 }
2718 /**
2719 * Is t an appropriate return type in an overrider for a
2720 * method that returns s?
2721 */
2722 public boolean covariantReturnType(Type t, Type s, Warner warner) {
2723 return
2724 isSameType(t, s) ||
2725 source.allowCovariantReturns() &&
2726 !t.isPrimitive() &&
2727 !s.isPrimitive() &&
2728 isAssignable(t, s, warner);
2729 }
2730 // </editor-fold>
2732 // <editor-fold defaultstate="collapsed" desc="Box/unbox support">
2733 /**
2734 * Return the class that boxes the given primitive.
2735 */
2736 public ClassSymbol boxedClass(Type t) {
2737 return reader.enterClass(syms.boxedName[t.tag]);
2738 }
2740 /**
2741 * Return the primitive type corresponding to a boxed type.
2742 */
2743 public Type unboxedType(Type t) {
2744 if (allowBoxing) {
2745 for (int i=0; i<syms.boxedName.length; i++) {
2746 Name box = syms.boxedName[i];
2747 if (box != null &&
2748 asSuper(t, reader.enterClass(box)) != null)
2749 return syms.typeOfTag[i];
2750 }
2751 }
2752 return Type.noType;
2753 }
2754 // </editor-fold>
2756 // <editor-fold defaultstate="collapsed" desc="Capture conversion">
2757 /*
2758 * JLS 3rd Ed. 5.1.10 Capture Conversion:
2759 *
2760 * Let G name a generic type declaration with n formal type
2761 * parameters A1 ... An with corresponding bounds U1 ... Un. There
2762 * exists a capture conversion from G<T1 ... Tn> to G<S1 ... Sn>,
2763 * where, for 1 <= i <= n:
2764 *
2765 * + If Ti is a wildcard type argument (4.5.1) of the form ? then
2766 * Si is a fresh type variable whose upper bound is
2767 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is the null
2768 * type.
2769 *
2770 * + If Ti is a wildcard type argument of the form ? extends Bi,
2771 * then Si is a fresh type variable whose upper bound is
2772 * glb(Bi, Ui[A1 := S1, ..., An := Sn]) and whose lower bound is
2773 * the null type, where glb(V1,... ,Vm) is V1 & ... & Vm. It is
2774 * a compile-time error if for any two classes (not interfaces)
2775 * Vi and Vj,Vi is not a subclass of Vj or vice versa.
2776 *
2777 * + If Ti is a wildcard type argument of the form ? super Bi,
2778 * then Si is a fresh type variable whose upper bound is
2779 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is Bi.
2780 *
2781 * + Otherwise, Si = Ti.
2782 *
2783 * Capture conversion on any type other than a parameterized type
2784 * (4.5) acts as an identity conversion (5.1.1). Capture
2785 * conversions never require a special action at run time and
2786 * therefore never throw an exception at run time.
2787 *
2788 * Capture conversion is not applied recursively.
2789 */
2790 /**
2791 * Capture conversion as specified by JLS 3rd Ed.
2792 */
2793 public Type capture(Type t) {
2794 if (t.tag != CLASS)
2795 return t;
2796 ClassType cls = (ClassType)t;
2797 if (cls.isRaw() || !cls.isParameterized())
2798 return cls;
2800 ClassType G = (ClassType)cls.asElement().asType();
2801 List<Type> A = G.getTypeArguments();
2802 List<Type> T = cls.getTypeArguments();
2803 List<Type> S = freshTypeVariables(T);
2805 List<Type> currentA = A;
2806 List<Type> currentT = T;
2807 List<Type> currentS = S;
2808 boolean captured = false;
2809 while (!currentA.isEmpty() &&
2810 !currentT.isEmpty() &&
2811 !currentS.isEmpty()) {
2812 if (currentS.head != currentT.head) {
2813 captured = true;
2814 WildcardType Ti = (WildcardType)currentT.head;
2815 Type Ui = currentA.head.getUpperBound();
2816 CapturedType Si = (CapturedType)currentS.head;
2817 if (Ui == null)
2818 Ui = syms.objectType;
2819 switch (Ti.kind) {
2820 case UNBOUND:
2821 Si.bound = subst(Ui, A, S);
2822 Si.lower = syms.botType;
2823 break;
2824 case EXTENDS:
2825 Si.bound = glb(Ti.getExtendsBound(), subst(Ui, A, S));
2826 Si.lower = syms.botType;
2827 break;
2828 case SUPER:
2829 Si.bound = subst(Ui, A, S);
2830 Si.lower = Ti.getSuperBound();
2831 break;
2832 }
2833 if (Si.bound == Si.lower)
2834 currentS.head = Si.bound;
2835 }
2836 currentA = currentA.tail;
2837 currentT = currentT.tail;
2838 currentS = currentS.tail;
2839 }
2840 if (!currentA.isEmpty() || !currentT.isEmpty() || !currentS.isEmpty())
2841 return erasure(t); // some "rare" type involved
2843 if (captured)
2844 return new ClassType(cls.getEnclosingType(), S, cls.tsym);
2845 else
2846 return t;
2847 }
2848 // where
2849 private List<Type> freshTypeVariables(List<Type> types) {
2850 ListBuffer<Type> result = lb();
2851 for (Type t : types) {
2852 if (t.tag == WILDCARD) {
2853 Type bound = ((WildcardType)t).getExtendsBound();
2854 if (bound == null)
2855 bound = syms.objectType;
2856 result.append(new CapturedType(capturedName,
2857 syms.noSymbol,
2858 bound,
2859 syms.botType,
2860 (WildcardType)t));
2861 } else {
2862 result.append(t);
2863 }
2864 }
2865 return result.toList();
2866 }
2867 // </editor-fold>
2869 // <editor-fold defaultstate="collapsed" desc="Internal utility methods">
2870 private List<Type> upperBounds(List<Type> ss) {
2871 if (ss.isEmpty()) return ss;
2872 Type head = upperBound(ss.head);
2873 List<Type> tail = upperBounds(ss.tail);
2874 if (head != ss.head || tail != ss.tail)
2875 return tail.prepend(head);
2876 else
2877 return ss;
2878 }
2880 private boolean sideCast(Type from, Type to, Warner warn) {
2881 // We are casting from type $from$ to type $to$, which are
2882 // non-final unrelated types. This method
2883 // tries to reject a cast by transferring type parameters
2884 // from $to$ to $from$ by common superinterfaces.
2885 boolean reverse = false;
2886 Type target = to;
2887 if ((to.tsym.flags() & INTERFACE) == 0) {
2888 assert (from.tsym.flags() & INTERFACE) != 0;
2889 reverse = true;
2890 to = from;
2891 from = target;
2892 }
2893 List<Type> commonSupers = superClosure(to, erasure(from));
2894 boolean giveWarning = commonSupers.isEmpty();
2895 // The arguments to the supers could be unified here to
2896 // get a more accurate analysis
2897 while (commonSupers.nonEmpty()) {
2898 Type t1 = asSuper(from, commonSupers.head.tsym);
2899 Type t2 = commonSupers.head; // same as asSuper(to, commonSupers.head.tsym);
2900 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
2901 return false;
2902 giveWarning = giveWarning || (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2));
2903 commonSupers = commonSupers.tail;
2904 }
2905 if (giveWarning && !isReifiable(to))
2906 warn.warnUnchecked();
2907 if (!source.allowCovariantReturns())
2908 // reject if there is a common method signature with
2909 // incompatible return types.
2910 chk.checkCompatibleAbstracts(warn.pos(), from, to);
2911 return true;
2912 }
2914 private boolean sideCastFinal(Type from, Type to, Warner warn) {
2915 // We are casting from type $from$ to type $to$, which are
2916 // unrelated types one of which is final and the other of
2917 // which is an interface. This method
2918 // tries to reject a cast by transferring type parameters
2919 // from the final class to the interface.
2920 boolean reverse = false;
2921 Type target = to;
2922 if ((to.tsym.flags() & INTERFACE) == 0) {
2923 assert (from.tsym.flags() & INTERFACE) != 0;
2924 reverse = true;
2925 to = from;
2926 from = target;
2927 }
2928 assert (from.tsym.flags() & FINAL) != 0;
2929 Type t1 = asSuper(from, to.tsym);
2930 if (t1 == null) return false;
2931 Type t2 = to;
2932 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
2933 return false;
2934 if (!source.allowCovariantReturns())
2935 // reject if there is a common method signature with
2936 // incompatible return types.
2937 chk.checkCompatibleAbstracts(warn.pos(), from, to);
2938 if (!isReifiable(target) &&
2939 (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2)))
2940 warn.warnUnchecked();
2941 return true;
2942 }
2944 private boolean giveWarning(Type from, Type to) {
2945 // To and from are (possibly different) parameterizations
2946 // of the same class or interface
2947 return to.isParameterized() && !containsType(to.getTypeArguments(), from.getTypeArguments());
2948 }
2950 private List<Type> superClosure(Type t, Type s) {
2951 List<Type> cl = List.nil();
2952 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
2953 if (isSubtype(s, erasure(l.head))) {
2954 cl = insert(cl, l.head);
2955 } else {
2956 cl = union(cl, superClosure(l.head, s));
2957 }
2958 }
2959 return cl;
2960 }
2962 private boolean containsTypeEquivalent(Type t, Type s) {
2963 return
2964 isSameType(t, s) || // shortcut
2965 containsType(t, s) && containsType(s, t);
2966 }
2968 /**
2969 * Adapt a type by computing a substitution which maps a source
2970 * type to a target type.
2971 *
2972 * @param source the source type
2973 * @param target the target type
2974 * @param from the type variables of the computed substitution
2975 * @param to the types of the computed substitution.
2976 */
2977 public void adapt(Type source,
2978 Type target,
2979 ListBuffer<Type> from,
2980 ListBuffer<Type> to) throws AdaptFailure {
2981 Map<Symbol,Type> mapping = new HashMap<Symbol,Type>();
2982 adaptRecursive(source, target, from, to, mapping);
2983 List<Type> fromList = from.toList();
2984 List<Type> toList = to.toList();
2985 while (!fromList.isEmpty()) {
2986 Type val = mapping.get(fromList.head.tsym);
2987 if (toList.head != val)
2988 toList.head = val;
2989 fromList = fromList.tail;
2990 toList = toList.tail;
2991 }
2992 }
2993 // where
2994 private void adaptRecursive(Type source,
2995 Type target,
2996 ListBuffer<Type> from,
2997 ListBuffer<Type> to,
2998 Map<Symbol,Type> mapping) throws AdaptFailure {
2999 if (source.tag == TYPEVAR) {
3000 // Check to see if there is
3001 // already a mapping for $source$, in which case
3002 // the old mapping will be merged with the new
3003 Type val = mapping.get(source.tsym);
3004 if (val != null) {
3005 if (val.isSuperBound() && target.isSuperBound()) {
3006 val = isSubtype(lowerBound(val), lowerBound(target))
3007 ? target : val;
3008 } else if (val.isExtendsBound() && target.isExtendsBound()) {
3009 val = isSubtype(upperBound(val), upperBound(target))
3010 ? val : target;
3011 } else if (!isSameType(val, target)) {
3012 throw new AdaptFailure();
3013 }
3014 } else {
3015 val = target;
3016 from.append(source);
3017 to.append(target);
3018 }
3019 mapping.put(source.tsym, val);
3020 } else if (source.tag == target.tag) {
3021 switch (source.tag) {
3022 case CLASS:
3023 adapt(source.allparams(), target.allparams(),
3024 from, to, mapping);
3025 break;
3026 case ARRAY:
3027 adaptRecursive(elemtype(source), elemtype(target),
3028 from, to, mapping);
3029 break;
3030 case WILDCARD:
3031 if (source.isExtendsBound()) {
3032 adaptRecursive(upperBound(source), upperBound(target),
3033 from, to, mapping);
3034 } else if (source.isSuperBound()) {
3035 adaptRecursive(lowerBound(source), lowerBound(target),
3036 from, to, mapping);
3037 }
3038 break;
3039 }
3040 }
3041 }
3042 public static class AdaptFailure extends Exception {
3043 static final long serialVersionUID = -7490231548272701566L;
3044 }
3046 /**
3047 * Adapt a type by computing a substitution which maps a list of
3048 * source types to a list of target types.
3049 *
3050 * @param source the source type
3051 * @param target the target type
3052 * @param from the type variables of the computed substitution
3053 * @param to the types of the computed substitution.
3054 */
3055 private void adapt(List<Type> source,
3056 List<Type> target,
3057 ListBuffer<Type> from,
3058 ListBuffer<Type> to,
3059 Map<Symbol,Type> mapping) throws AdaptFailure {
3060 if (source.length() == target.length()) {
3061 while (source.nonEmpty()) {
3062 adaptRecursive(source.head, target.head, from, to, mapping);
3063 source = source.tail;
3064 target = target.tail;
3065 }
3066 }
3067 }
3069 private void adaptSelf(Type t,
3070 ListBuffer<Type> from,
3071 ListBuffer<Type> to) {
3072 try {
3073 //if (t.tsym.type != t)
3074 adapt(t.tsym.type, t, from, to);
3075 } catch (AdaptFailure ex) {
3076 // Adapt should never fail calculating a mapping from
3077 // t.tsym.type to t as there can be no merge problem.
3078 throw new AssertionError(ex);
3079 }
3080 }
3082 /**
3083 * Rewrite all type variables (universal quantifiers) in the given
3084 * type to wildcards (existential quantifiers). This is used to
3085 * determine if a cast is allowed. For example, if high is true
3086 * and {@code T <: Number}, then {@code List<T>} is rewritten to
3087 * {@code List<? extends Number>}. Since {@code List<Integer> <:
3088 * List<? extends Number>} a {@code List<T>} can be cast to {@code
3089 * List<Integer>} with a warning.
3090 * @param t a type
3091 * @param high if true return an upper bound; otherwise a lower
3092 * bound
3093 * @param rewriteTypeVars only rewrite captured wildcards if false;
3094 * otherwise rewrite all type variables
3095 * @return the type rewritten with wildcards (existential
3096 * quantifiers) only
3097 */
3098 private Type rewriteQuantifiers(Type t, boolean high, boolean rewriteTypeVars) {
3099 ListBuffer<Type> from = new ListBuffer<Type>();
3100 ListBuffer<Type> to = new ListBuffer<Type>();
3101 adaptSelf(t, from, to);
3102 ListBuffer<Type> rewritten = new ListBuffer<Type>();
3103 List<Type> formals = from.toList();
3104 boolean changed = false;
3105 for (Type arg : to.toList()) {
3106 Type bound;
3107 if (rewriteTypeVars && arg.tag == TYPEVAR) {
3108 TypeVar tv = (TypeVar)arg;
3109 bound = high ? tv.bound : syms.botType;
3110 } else {
3111 bound = high ? upperBound(arg) : lowerBound(arg);
3112 }
3113 Type newarg = bound;
3114 if (arg != bound) {
3115 changed = true;
3116 newarg = high ? makeExtendsWildcard(bound, (TypeVar)formals.head)
3117 : makeSuperWildcard(bound, (TypeVar)formals.head);
3118 }
3119 rewritten.append(newarg);
3120 formals = formals.tail;
3121 }
3122 if (changed)
3123 return subst(t.tsym.type, from.toList(), rewritten.toList());
3124 else
3125 return t;
3126 }
3128 /**
3129 * Create a wildcard with the given upper (extends) bound; create
3130 * an unbounded wildcard if bound is Object.
3131 *
3132 * @param bound the upper bound
3133 * @param formal the formal type parameter that will be
3134 * substituted by the wildcard
3135 */
3136 private WildcardType makeExtendsWildcard(Type bound, TypeVar formal) {
3137 if (bound == syms.objectType) {
3138 return new WildcardType(syms.objectType,
3139 BoundKind.UNBOUND,
3140 syms.boundClass,
3141 formal);
3142 } else {
3143 return new WildcardType(bound,
3144 BoundKind.EXTENDS,
3145 syms.boundClass,
3146 formal);
3147 }
3148 }
3150 /**
3151 * Create a wildcard with the given lower (super) bound; create an
3152 * unbounded wildcard if bound is bottom (type of {@code null}).
3153 *
3154 * @param bound the lower bound
3155 * @param formal the formal type parameter that will be
3156 * substituted by the wildcard
3157 */
3158 private WildcardType makeSuperWildcard(Type bound, TypeVar formal) {
3159 if (bound.tag == BOT) {
3160 return new WildcardType(syms.objectType,
3161 BoundKind.UNBOUND,
3162 syms.boundClass,
3163 formal);
3164 } else {
3165 return new WildcardType(bound,
3166 BoundKind.SUPER,
3167 syms.boundClass,
3168 formal);
3169 }
3170 }
3172 /**
3173 * A wrapper for a type that allows use in sets.
3174 */
3175 class SingletonType {
3176 final Type t;
3177 SingletonType(Type t) {
3178 this.t = t;
3179 }
3180 public int hashCode() {
3181 return Types.this.hashCode(t);
3182 }
3183 public boolean equals(Object obj) {
3184 return (obj instanceof SingletonType) &&
3185 isSameType(t, ((SingletonType)obj).t);
3186 }
3187 public String toString() {
3188 return t.toString();
3189 }
3190 }
3191 // </editor-fold>
3193 // <editor-fold defaultstate="collapsed" desc="Visitors">
3194 /**
3195 * A default visitor for types. All visitor methods except
3196 * visitType are implemented by delegating to visitType. Concrete
3197 * subclasses must provide an implementation of visitType and can
3198 * override other methods as needed.
3199 *
3200 * @param <R> the return type of the operation implemented by this
3201 * visitor; use Void if no return type is needed.
3202 * @param <S> the type of the second argument (the first being the
3203 * type itself) of the operation implemented by this visitor; use
3204 * Void if a second argument is not needed.
3205 */
3206 public static abstract class DefaultTypeVisitor<R,S> implements Type.Visitor<R,S> {
3207 final public R visit(Type t, S s) { return t.accept(this, s); }
3208 public R visitClassType(ClassType t, S s) { return visitType(t, s); }
3209 public R visitWildcardType(WildcardType t, S s) { return visitType(t, s); }
3210 public R visitArrayType(ArrayType t, S s) { return visitType(t, s); }
3211 public R visitMethodType(MethodType t, S s) { return visitType(t, s); }
3212 public R visitPackageType(PackageType t, S s) { return visitType(t, s); }
3213 public R visitTypeVar(TypeVar t, S s) { return visitType(t, s); }
3214 public R visitCapturedType(CapturedType t, S s) { return visitType(t, s); }
3215 public R visitForAll(ForAll t, S s) { return visitType(t, s); }
3216 public R visitUndetVar(UndetVar t, S s) { return visitType(t, s); }
3217 public R visitErrorType(ErrorType t, S s) { return visitType(t, s); }
3218 }
3220 /**
3221 * A <em>simple</em> visitor for types. This visitor is simple as
3222 * captured wildcards, for-all types (generic methods), and
3223 * undetermined type variables (part of inference) are hidden.
3224 * Captured wildcards are hidden by treating them as type
3225 * variables and the rest are hidden by visiting their qtypes.
3226 *
3227 * @param <R> the return type of the operation implemented by this
3228 * visitor; use Void if no return type is needed.
3229 * @param <S> the type of the second argument (the first being the
3230 * type itself) of the operation implemented by this visitor; use
3231 * Void if a second argument is not needed.
3232 */
3233 public static abstract class SimpleVisitor<R,S> extends DefaultTypeVisitor<R,S> {
3234 @Override
3235 public R visitCapturedType(CapturedType t, S s) {
3236 return visitTypeVar(t, s);
3237 }
3238 @Override
3239 public R visitForAll(ForAll t, S s) {
3240 return visit(t.qtype, s);
3241 }
3242 @Override
3243 public R visitUndetVar(UndetVar t, S s) {
3244 return visit(t.qtype, s);
3245 }
3246 }
3248 /**
3249 * A plain relation on types. That is a 2-ary function on the
3250 * form Type × Type → Boolean.
3251 * <!-- In plain text: Type x Type -> Boolean -->
3252 */
3253 public static abstract class TypeRelation extends SimpleVisitor<Boolean,Type> {}
3255 /**
3256 * A convenience visitor for implementing operations that only
3257 * require one argument (the type itself), that is, unary
3258 * operations.
3259 *
3260 * @param <R> the return type of the operation implemented by this
3261 * visitor; use Void if no return type is needed.
3262 */
3263 public static abstract class UnaryVisitor<R> extends SimpleVisitor<R,Void> {
3264 final public R visit(Type t) { return t.accept(this, null); }
3265 }
3267 /**
3268 * A visitor for implementing a mapping from types to types. The
3269 * default behavior of this class is to implement the identity
3270 * mapping (mapping a type to itself). This can be overridden in
3271 * subclasses.
3272 *
3273 * @param <S> the type of the second argument (the first being the
3274 * type itself) of this mapping; use Void if a second argument is
3275 * not needed.
3276 */
3277 public static class MapVisitor<S> extends DefaultTypeVisitor<Type,S> {
3278 final public Type visit(Type t) { return t.accept(this, null); }
3279 public Type visitType(Type t, S s) { return t; }
3280 }
3281 // </editor-fold>
3282 }
