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src/share/classes/com/sun/tools/javac/code/Types.java@9a66ca7c79fa
src/share/classes/com/sun/tools/javac/code/Types.java
Sat, 01 Dec 2007 00:00:00 +0000
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- duke
- date
- Sat, 01 Dec 2007 00:00:00 +0000
- changeset 1
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1 /*
2 * Copyright 2003-2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
26 package com.sun.tools.javac.code;
28 import java.util.*;
30 import com.sun.tools.javac.util.*;
31 import com.sun.tools.javac.util.List;
33 import com.sun.tools.javac.jvm.ClassReader;
34 import com.sun.tools.javac.comp.Infer;
35 import com.sun.tools.javac.comp.Check;
37 import static com.sun.tools.javac.code.Type.*;
38 import static com.sun.tools.javac.code.TypeTags.*;
39 import static com.sun.tools.javac.code.Symbol.*;
40 import static com.sun.tools.javac.code.Flags.*;
41 import static com.sun.tools.javac.code.BoundKind.*;
42 import static com.sun.tools.javac.util.ListBuffer.lb;
44 /**
45 * Utility class containing various operations on types.
46 *
47 * <p>Unless other names are more illustrative, the following naming
48 * conventions should be observed in this file:
49 *
50 * <dl>
51 * <dt>t</dt>
52 * <dd>If the first argument to an operation is a type, it should be named t.</dd>
53 * <dt>s</dt>
54 * <dd>Similarly, if the second argument to an operation is a type, it should be named s.</dd>
55 * <dt>ts</dt>
56 * <dd>If an operations takes a list of types, the first should be named ts.</dd>
57 * <dt>ss</dt>
58 * <dd>A second list of types should be named ss.</dd>
59 * </dl>
60 *
61 * <p><b>This is NOT part of any API supported by Sun Microsystems.
62 * If you write code that depends on this, you do so at your own risk.
63 * This code and its internal interfaces are subject to change or
64 * deletion without notice.</b>
65 */
66 public class Types {
67 protected static final Context.Key<Types> typesKey =
68 new Context.Key<Types>();
70 final Symtab syms;
71 final Name.Table names;
72 final boolean allowBoxing;
73 final ClassReader reader;
74 final Source source;
75 final Check chk;
76 List<Warner> warnStack = List.nil();
77 final Name capturedName;
79 // <editor-fold defaultstate="collapsed" desc="Instantiating">
80 public static Types instance(Context context) {
81 Types instance = context.get(typesKey);
82 if (instance == null)
83 instance = new Types(context);
84 return instance;
85 }
87 protected Types(Context context) {
88 context.put(typesKey, this);
89 syms = Symtab.instance(context);
90 names = Name.Table.instance(context);
91 allowBoxing = Source.instance(context).allowBoxing();
92 reader = ClassReader.instance(context);
93 source = Source.instance(context);
94 chk = Check.instance(context);
95 capturedName = names.fromString("<captured wildcard>");
96 }
97 // </editor-fold>
99 // <editor-fold defaultstate="collapsed" desc="upperBound">
100 /**
101 * The "rvalue conversion".<br>
102 * The upper bound of most types is the type
103 * itself. Wildcards, on the other hand have upper
104 * and lower bounds.
105 * @param t a type
106 * @return the upper bound of the given type
107 */
108 public Type upperBound(Type t) {
109 return upperBound.visit(t);
110 }
111 // where
112 private final MapVisitor<Void> upperBound = new MapVisitor<Void>() {
114 @Override
115 public Type visitWildcardType(WildcardType t, Void ignored) {
116 if (t.isSuperBound())
117 return t.bound == null ? syms.objectType : t.bound.bound;
118 else
119 return visit(t.type);
120 }
122 @Override
123 public Type visitCapturedType(CapturedType t, Void ignored) {
124 return visit(t.bound);
125 }
126 };
127 // </editor-fold>
129 // <editor-fold defaultstate="collapsed" desc="lowerBound">
130 /**
131 * The "lvalue conversion".<br>
132 * The lower bound of most types is the type
133 * itself. Wildcards, on the other hand have upper
134 * and lower bounds.
135 * @param t a type
136 * @return the lower bound of the given type
137 */
138 public Type lowerBound(Type t) {
139 return lowerBound.visit(t);
140 }
141 // where
142 private final MapVisitor<Void> lowerBound = new MapVisitor<Void>() {
144 @Override
145 public Type visitWildcardType(WildcardType t, Void ignored) {
146 return t.isExtendsBound() ? syms.botType : visit(t.type);
147 }
149 @Override
150 public Type visitCapturedType(CapturedType t, Void ignored) {
151 return visit(t.getLowerBound());
152 }
153 };
154 // </editor-fold>
156 // <editor-fold defaultstate="collapsed" desc="isUnbounded">
157 /**
158 * Checks that all the arguments to a class are unbounded
159 * wildcards or something else that doesn't make any restrictions
160 * on the arguments. If a class isUnbounded, a raw super- or
161 * subclass can be cast to it without a warning.
162 * @param t a type
163 * @return true iff the given type is unbounded or raw
164 */
165 public boolean isUnbounded(Type t) {
166 return isUnbounded.visit(t);
167 }
168 // where
169 private final UnaryVisitor<Boolean> isUnbounded = new UnaryVisitor<Boolean>() {
171 public Boolean visitType(Type t, Void ignored) {
172 return true;
173 }
175 @Override
176 public Boolean visitClassType(ClassType t, Void ignored) {
177 List<Type> parms = t.tsym.type.allparams();
178 List<Type> args = t.allparams();
179 while (parms.nonEmpty()) {
180 WildcardType unb = new WildcardType(syms.objectType,
181 BoundKind.UNBOUND,
182 syms.boundClass,
183 (TypeVar)parms.head);
184 if (!containsType(args.head, unb))
185 return false;
186 parms = parms.tail;
187 args = args.tail;
188 }
189 return true;
190 }
191 };
192 // </editor-fold>
194 // <editor-fold defaultstate="collapsed" desc="asSub">
195 /**
196 * Return the least specific subtype of t that starts with symbol
197 * sym. If none exists, return null. The least specific subtype
198 * is determined as follows:
199 *
200 * <p>If there is exactly one parameterized instance of sym that is a
201 * subtype of t, that parameterized instance is returned.<br>
202 * Otherwise, if the plain type or raw type `sym' is a subtype of
203 * type t, the type `sym' itself is returned. Otherwise, null is
204 * returned.
205 */
206 public Type asSub(Type t, Symbol sym) {
207 return asSub.visit(t, sym);
208 }
209 // where
210 private final SimpleVisitor<Type,Symbol> asSub = new SimpleVisitor<Type,Symbol>() {
212 public Type visitType(Type t, Symbol sym) {
213 return null;
214 }
216 @Override
217 public Type visitClassType(ClassType t, Symbol sym) {
218 if (t.tsym == sym)
219 return t;
220 Type base = asSuper(sym.type, t.tsym);
221 if (base == null)
222 return null;
223 ListBuffer<Type> from = new ListBuffer<Type>();
224 ListBuffer<Type> to = new ListBuffer<Type>();
225 try {
226 adapt(base, t, from, to);
227 } catch (AdaptFailure ex) {
228 return null;
229 }
230 Type res = subst(sym.type, from.toList(), to.toList());
231 if (!isSubtype(res, t))
232 return null;
233 ListBuffer<Type> openVars = new ListBuffer<Type>();
234 for (List<Type> l = sym.type.allparams();
235 l.nonEmpty(); l = l.tail)
236 if (res.contains(l.head) && !t.contains(l.head))
237 openVars.append(l.head);
238 if (openVars.nonEmpty()) {
239 if (t.isRaw()) {
240 // The subtype of a raw type is raw
241 res = erasure(res);
242 } else {
243 // Unbound type arguments default to ?
244 List<Type> opens = openVars.toList();
245 ListBuffer<Type> qs = new ListBuffer<Type>();
246 for (List<Type> iter = opens; iter.nonEmpty(); iter = iter.tail) {
247 qs.append(new WildcardType(syms.objectType, BoundKind.UNBOUND, syms.boundClass, (TypeVar) iter.head));
248 }
249 res = subst(res, opens, qs.toList());
250 }
251 }
252 return res;
253 }
255 @Override
256 public Type visitErrorType(ErrorType t, Symbol sym) {
257 return t;
258 }
259 };
260 // </editor-fold>
262 // <editor-fold defaultstate="collapsed" desc="isConvertible">
263 /**
264 * Is t a subtype of or convertiable via boxing/unboxing
265 * convertions to s?
266 */
267 public boolean isConvertible(Type t, Type s, Warner warn) {
268 boolean tPrimitive = t.isPrimitive();
269 boolean sPrimitive = s.isPrimitive();
270 if (tPrimitive == sPrimitive)
271 return isSubtypeUnchecked(t, s, warn);
272 if (!allowBoxing) return false;
273 return tPrimitive
274 ? isSubtype(boxedClass(t).type, s)
275 : isSubtype(unboxedType(t), s);
276 }
278 /**
279 * Is t a subtype of or convertiable via boxing/unboxing
280 * convertions to s?
281 */
282 public boolean isConvertible(Type t, Type s) {
283 return isConvertible(t, s, Warner.noWarnings);
284 }
285 // </editor-fold>
287 // <editor-fold defaultstate="collapsed" desc="isSubtype">
288 /**
289 * Is t an unchecked subtype of s?
290 */
291 public boolean isSubtypeUnchecked(Type t, Type s) {
292 return isSubtypeUnchecked(t, s, Warner.noWarnings);
293 }
294 /**
295 * Is t an unchecked subtype of s?
296 */
297 public boolean isSubtypeUnchecked(Type t, Type s, Warner warn) {
298 if (t.tag == ARRAY && s.tag == ARRAY) {
299 return (((ArrayType)t).elemtype.tag <= lastBaseTag)
300 ? isSameType(elemtype(t), elemtype(s))
301 : isSubtypeUnchecked(elemtype(t), elemtype(s), warn);
302 } else if (isSubtype(t, s)) {
303 return true;
304 } else if (!s.isRaw()) {
305 Type t2 = asSuper(t, s.tsym);
306 if (t2 != null && t2.isRaw()) {
307 if (isReifiable(s))
308 warn.silentUnchecked();
309 else
310 warn.warnUnchecked();
311 return true;
312 }
313 }
314 return false;
315 }
317 /**
318 * Is t a subtype of s?<br>
319 * (not defined for Method and ForAll types)
320 */
321 final public boolean isSubtype(Type t, Type s) {
322 return isSubtype(t, s, true);
323 }
324 final public boolean isSubtypeNoCapture(Type t, Type s) {
325 return isSubtype(t, s, false);
326 }
327 public boolean isSubtype(Type t, Type s, boolean capture) {
328 if (t == s)
329 return true;
331 if (s.tag >= firstPartialTag)
332 return isSuperType(s, t);
334 Type lower = lowerBound(s);
335 if (s != lower)
336 return isSubtype(capture ? capture(t) : t, lower, false);
338 return isSubtype.visit(capture ? capture(t) : t, s);
339 }
340 // where
341 private TypeRelation isSubtype = new TypeRelation()
342 {
343 public Boolean visitType(Type t, Type s) {
344 switch (t.tag) {
345 case BYTE: case CHAR:
346 return (t.tag == s.tag ||
347 t.tag + 2 <= s.tag && s.tag <= DOUBLE);
348 case SHORT: case INT: case LONG: case FLOAT: case DOUBLE:
349 return t.tag <= s.tag && s.tag <= DOUBLE;
350 case BOOLEAN: case VOID:
351 return t.tag == s.tag;
352 case TYPEVAR:
353 return isSubtypeNoCapture(t.getUpperBound(), s);
354 case BOT:
355 return
356 s.tag == BOT || s.tag == CLASS ||
357 s.tag == ARRAY || s.tag == TYPEVAR;
358 case NONE:
359 return false;
360 default:
361 throw new AssertionError("isSubtype " + t.tag);
362 }
363 }
365 private Set<TypePair> cache = new HashSet<TypePair>();
367 private boolean containsTypeRecursive(Type t, Type s) {
368 TypePair pair = new TypePair(t, s);
369 if (cache.add(pair)) {
370 try {
371 return containsType(t.getTypeArguments(),
372 s.getTypeArguments());
373 } finally {
374 cache.remove(pair);
375 }
376 } else {
377 return containsType(t.getTypeArguments(),
378 rewriteSupers(s).getTypeArguments());
379 }
380 }
382 private Type rewriteSupers(Type t) {
383 if (!t.isParameterized())
384 return t;
385 ListBuffer<Type> from = lb();
386 ListBuffer<Type> to = lb();
387 adaptSelf(t, from, to);
388 if (from.isEmpty())
389 return t;
390 ListBuffer<Type> rewrite = lb();
391 boolean changed = false;
392 for (Type orig : to.toList()) {
393 Type s = rewriteSupers(orig);
394 if (s.isSuperBound() && !s.isExtendsBound()) {
395 s = new WildcardType(syms.objectType,
396 BoundKind.UNBOUND,
397 syms.boundClass);
398 changed = true;
399 } else if (s != orig) {
400 s = new WildcardType(upperBound(s),
401 BoundKind.EXTENDS,
402 syms.boundClass);
403 changed = true;
404 }
405 rewrite.append(s);
406 }
407 if (changed)
408 return subst(t.tsym.type, from.toList(), rewrite.toList());
409 else
410 return t;
411 }
413 @Override
414 public Boolean visitClassType(ClassType t, Type s) {
415 Type sup = asSuper(t, s.tsym);
416 return sup != null
417 && sup.tsym == s.tsym
418 // You're not allowed to write
419 // Vector<Object> vec = new Vector<String>();
420 // But with wildcards you can write
421 // Vector<? extends Object> vec = new Vector<String>();
422 // which means that subtype checking must be done
423 // here instead of same-type checking (via containsType).
424 && (!s.isParameterized() || containsTypeRecursive(s, sup))
425 && isSubtypeNoCapture(sup.getEnclosingType(),
426 s.getEnclosingType());
427 }
429 @Override
430 public Boolean visitArrayType(ArrayType t, Type s) {
431 if (s.tag == ARRAY) {
432 if (t.elemtype.tag <= lastBaseTag)
433 return isSameType(t.elemtype, elemtype(s));
434 else
435 return isSubtypeNoCapture(t.elemtype, elemtype(s));
436 }
438 if (s.tag == CLASS) {
439 Name sname = s.tsym.getQualifiedName();
440 return sname == names.java_lang_Object
441 || sname == names.java_lang_Cloneable
442 || sname == names.java_io_Serializable;
443 }
445 return false;
446 }
448 @Override
449 public Boolean visitUndetVar(UndetVar t, Type s) {
450 //todo: test against origin needed? or replace with substitution?
451 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
452 return true;
454 if (t.inst != null)
455 return isSubtypeNoCapture(t.inst, s); // TODO: ", warn"?
457 t.hibounds = t.hibounds.prepend(s);
458 return true;
459 }
461 @Override
462 public Boolean visitErrorType(ErrorType t, Type s) {
463 return true;
464 }
465 };
467 /**
468 * Is t a subtype of every type in given list `ts'?<br>
469 * (not defined for Method and ForAll types)<br>
470 * Allows unchecked conversions.
471 */
472 public boolean isSubtypeUnchecked(Type t, List<Type> ts, Warner warn) {
473 for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
474 if (!isSubtypeUnchecked(t, l.head, warn))
475 return false;
476 return true;
477 }
479 /**
480 * Are corresponding elements of ts subtypes of ss? If lists are
481 * of different length, return false.
482 */
483 public boolean isSubtypes(List<Type> ts, List<Type> ss) {
484 while (ts.tail != null && ss.tail != null
485 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
486 isSubtype(ts.head, ss.head)) {
487 ts = ts.tail;
488 ss = ss.tail;
489 }
490 return ts.tail == null && ss.tail == null;
491 /*inlined: ts.isEmpty() && ss.isEmpty();*/
492 }
494 /**
495 * Are corresponding elements of ts subtypes of ss, allowing
496 * unchecked conversions? If lists are of different length,
497 * return false.
498 **/
499 public boolean isSubtypesUnchecked(List<Type> ts, List<Type> ss, Warner warn) {
500 while (ts.tail != null && ss.tail != null
501 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
502 isSubtypeUnchecked(ts.head, ss.head, warn)) {
503 ts = ts.tail;
504 ss = ss.tail;
505 }
506 return ts.tail == null && ss.tail == null;
507 /*inlined: ts.isEmpty() && ss.isEmpty();*/
508 }
509 // </editor-fold>
511 // <editor-fold defaultstate="collapsed" desc="isSuperType">
512 /**
513 * Is t a supertype of s?
514 */
515 public boolean isSuperType(Type t, Type s) {
516 switch (t.tag) {
517 case ERROR:
518 return true;
519 case UNDETVAR: {
520 UndetVar undet = (UndetVar)t;
521 if (t == s ||
522 undet.qtype == s ||
523 s.tag == ERROR ||
524 s.tag == BOT) return true;
525 if (undet.inst != null)
526 return isSubtype(s, undet.inst);
527 undet.lobounds = undet.lobounds.prepend(s);
528 return true;
529 }
530 default:
531 return isSubtype(s, t);
532 }
533 }
534 // </editor-fold>
536 // <editor-fold defaultstate="collapsed" desc="isSameType">
537 /**
538 * Are corresponding elements of the lists the same type? If
539 * lists are of different length, return false.
540 */
541 public boolean isSameTypes(List<Type> ts, List<Type> ss) {
542 while (ts.tail != null && ss.tail != null
543 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
544 isSameType(ts.head, ss.head)) {
545 ts = ts.tail;
546 ss = ss.tail;
547 }
548 return ts.tail == null && ss.tail == null;
549 /*inlined: ts.isEmpty() && ss.isEmpty();*/
550 }
552 /**
553 * Is t the same type as s?
554 */
555 public boolean isSameType(Type t, Type s) {
556 return isSameType.visit(t, s);
557 }
558 // where
559 private TypeRelation isSameType = new TypeRelation() {
561 public Boolean visitType(Type t, Type s) {
562 if (t == s)
563 return true;
565 if (s.tag >= firstPartialTag)
566 return visit(s, t);
568 switch (t.tag) {
569 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
570 case DOUBLE: case BOOLEAN: case VOID: case BOT: case NONE:
571 return t.tag == s.tag;
572 case TYPEVAR:
573 return s.isSuperBound()
574 && !s.isExtendsBound()
575 && visit(t, upperBound(s));
576 default:
577 throw new AssertionError("isSameType " + t.tag);
578 }
579 }
581 @Override
582 public Boolean visitWildcardType(WildcardType t, Type s) {
583 if (s.tag >= firstPartialTag)
584 return visit(s, t);
585 else
586 return false;
587 }
589 @Override
590 public Boolean visitClassType(ClassType t, Type s) {
591 if (t == s)
592 return true;
594 if (s.tag >= firstPartialTag)
595 return visit(s, t);
597 if (s.isSuperBound() && !s.isExtendsBound())
598 return visit(t, upperBound(s)) && visit(t, lowerBound(s));
600 if (t.isCompound() && s.isCompound()) {
601 if (!visit(supertype(t), supertype(s)))
602 return false;
604 HashSet<SingletonType> set = new HashSet<SingletonType>();
605 for (Type x : interfaces(t))
606 set.add(new SingletonType(x));
607 for (Type x : interfaces(s)) {
608 if (!set.remove(new SingletonType(x)))
609 return false;
610 }
611 return (set.size() == 0);
612 }
613 return t.tsym == s.tsym
614 && visit(t.getEnclosingType(), s.getEnclosingType())
615 && containsTypeEquivalent(t.getTypeArguments(), s.getTypeArguments());
616 }
618 @Override
619 public Boolean visitArrayType(ArrayType t, Type s) {
620 if (t == s)
621 return true;
623 if (s.tag >= firstPartialTag)
624 return visit(s, t);
626 return s.tag == ARRAY
627 && containsTypeEquivalent(t.elemtype, elemtype(s));
628 }
630 @Override
631 public Boolean visitMethodType(MethodType t, Type s) {
632 // isSameType for methods does not take thrown
633 // exceptions into account!
634 return hasSameArgs(t, s) && visit(t.getReturnType(), s.getReturnType());
635 }
637 @Override
638 public Boolean visitPackageType(PackageType t, Type s) {
639 return t == s;
640 }
642 @Override
643 public Boolean visitForAll(ForAll t, Type s) {
644 if (s.tag != FORALL)
645 return false;
647 ForAll forAll = (ForAll)s;
648 return hasSameBounds(t, forAll)
649 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
650 }
652 @Override
653 public Boolean visitUndetVar(UndetVar t, Type s) {
654 if (s.tag == WILDCARD)
655 // FIXME, this might be leftovers from before capture conversion
656 return false;
658 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
659 return true;
661 if (t.inst != null)
662 return visit(t.inst, s);
664 t.inst = fromUnknownFun.apply(s);
665 for (List<Type> l = t.lobounds; l.nonEmpty(); l = l.tail) {
666 if (!isSubtype(l.head, t.inst))
667 return false;
668 }
669 for (List<Type> l = t.hibounds; l.nonEmpty(); l = l.tail) {
670 if (!isSubtype(t.inst, l.head))
671 return false;
672 }
673 return true;
674 }
676 @Override
677 public Boolean visitErrorType(ErrorType t, Type s) {
678 return true;
679 }
680 };
681 // </editor-fold>
683 // <editor-fold defaultstate="collapsed" desc="fromUnknownFun">
684 /**
685 * A mapping that turns all unknown types in this type to fresh
686 * unknown variables.
687 */
688 public Mapping fromUnknownFun = new Mapping("fromUnknownFun") {
689 public Type apply(Type t) {
690 if (t.tag == UNKNOWN) return new UndetVar(t);
691 else return t.map(this);
692 }
693 };
694 // </editor-fold>
696 // <editor-fold defaultstate="collapsed" desc="Contains Type">
697 public boolean containedBy(Type t, Type s) {
698 switch (t.tag) {
699 case UNDETVAR:
700 if (s.tag == WILDCARD) {
701 UndetVar undetvar = (UndetVar)t;
703 // Because of wildcard capture, s must be on the left
704 // hand side of an assignment. Furthermore, t is an
705 // underconstrained type variable, for example, one
706 // that is only used in the return type of a method.
707 // If the type variable is truly underconstrained, it
708 // cannot have any low bounds:
709 assert undetvar.lobounds.isEmpty() : undetvar;
711 undetvar.inst = glb(upperBound(s), undetvar.inst);
712 return true;
713 } else {
714 return isSameType(t, s);
715 }
716 case ERROR:
717 return true;
718 default:
719 return containsType(s, t);
720 }
721 }
723 boolean containsType(List<Type> ts, List<Type> ss) {
724 while (ts.nonEmpty() && ss.nonEmpty()
725 && containsType(ts.head, ss.head)) {
726 ts = ts.tail;
727 ss = ss.tail;
728 }
729 return ts.isEmpty() && ss.isEmpty();
730 }
732 /**
733 * Check if t contains s.
734 *
735 * <p>T contains S if:
736 *
737 * <p>{@code L(T) <: L(S) && U(S) <: U(T)}
738 *
739 * <p>This relation is only used by ClassType.isSubtype(), that
740 * is,
741 *
742 * <p>{@code C<S> <: C<T> if T contains S.}
743 *
744 * <p>Because of F-bounds, this relation can lead to infinite
745 * recursion. Thus we must somehow break that recursion. Notice
746 * that containsType() is only called from ClassType.isSubtype().
747 * Since the arguments have already been checked against their
748 * bounds, we know:
749 *
750 * <p>{@code U(S) <: U(T) if T is "super" bound (U(T) *is* the bound)}
751 *
752 * <p>{@code L(T) <: L(S) if T is "extends" bound (L(T) is bottom)}
753 *
754 * @param t a type
755 * @param s a type
756 */
757 public boolean containsType(Type t, Type s) {
758 return containsType.visit(t, s);
759 }
760 // where
761 private TypeRelation containsType = new TypeRelation() {
763 private Type U(Type t) {
764 while (t.tag == WILDCARD) {
765 WildcardType w = (WildcardType)t;
766 if (w.isSuperBound())
767 return w.bound == null ? syms.objectType : w.bound.bound;
768 else
769 t = w.type;
770 }
771 return t;
772 }
774 private Type L(Type t) {
775 while (t.tag == WILDCARD) {
776 WildcardType w = (WildcardType)t;
777 if (w.isExtendsBound())
778 return syms.botType;
779 else
780 t = w.type;
781 }
782 return t;
783 }
785 public Boolean visitType(Type t, Type s) {
786 if (s.tag >= firstPartialTag)
787 return containedBy(s, t);
788 else
789 return isSameType(t, s);
790 }
792 void debugContainsType(WildcardType t, Type s) {
793 System.err.println();
794 System.err.format(" does %s contain %s?%n", t, s);
795 System.err.format(" %s U(%s) <: U(%s) %s = %s%n",
796 upperBound(s), s, t, U(t),
797 t.isSuperBound()
798 || isSubtypeNoCapture(upperBound(s), U(t)));
799 System.err.format(" %s L(%s) <: L(%s) %s = %s%n",
800 L(t), t, s, lowerBound(s),
801 t.isExtendsBound()
802 || isSubtypeNoCapture(L(t), lowerBound(s)));
803 System.err.println();
804 }
806 @Override
807 public Boolean visitWildcardType(WildcardType t, Type s) {
808 if (s.tag >= firstPartialTag)
809 return containedBy(s, t);
810 else {
811 // debugContainsType(t, s);
812 return isSameWildcard(t, s)
813 || isCaptureOf(s, t)
814 || ((t.isExtendsBound() || isSubtypeNoCapture(L(t), lowerBound(s))) &&
815 (t.isSuperBound() || isSubtypeNoCapture(upperBound(s), U(t))));
816 }
817 }
819 @Override
820 public Boolean visitUndetVar(UndetVar t, Type s) {
821 if (s.tag != WILDCARD)
822 return isSameType(t, s);
823 else
824 return false;
825 }
827 @Override
828 public Boolean visitErrorType(ErrorType t, Type s) {
829 return true;
830 }
831 };
833 public boolean isCaptureOf(Type s, WildcardType t) {
834 if (s.tag != TYPEVAR || !(s instanceof CapturedType))
835 return false;
836 return isSameWildcard(t, ((CapturedType)s).wildcard);
837 }
839 public boolean isSameWildcard(WildcardType t, Type s) {
840 if (s.tag != WILDCARD)
841 return false;
842 WildcardType w = (WildcardType)s;
843 return w.kind == t.kind && w.type == t.type;
844 }
846 public boolean containsTypeEquivalent(List<Type> ts, List<Type> ss) {
847 while (ts.nonEmpty() && ss.nonEmpty()
848 && containsTypeEquivalent(ts.head, ss.head)) {
849 ts = ts.tail;
850 ss = ss.tail;
851 }
852 return ts.isEmpty() && ss.isEmpty();
853 }
854 // </editor-fold>
856 // <editor-fold defaultstate="collapsed" desc="isCastable">
857 public boolean isCastable(Type t, Type s) {
858 return isCastable(t, s, Warner.noWarnings);
859 }
861 /**
862 * Is t is castable to s?<br>
863 * s is assumed to be an erased type.<br>
864 * (not defined for Method and ForAll types).
865 */
866 public boolean isCastable(Type t, Type s, Warner warn) {
867 if (t == s)
868 return true;
870 if (t.isPrimitive() != s.isPrimitive())
871 return allowBoxing && isConvertible(t, s, warn);
873 if (warn != warnStack.head) {
874 try {
875 warnStack = warnStack.prepend(warn);
876 return isCastable.visit(t, s);
877 } finally {
878 warnStack = warnStack.tail;
879 }
880 } else {
881 return isCastable.visit(t, s);
882 }
883 }
884 // where
885 private TypeRelation isCastable = new TypeRelation() {
887 public Boolean visitType(Type t, Type s) {
888 if (s.tag == ERROR)
889 return true;
891 switch (t.tag) {
892 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
893 case DOUBLE:
894 return s.tag <= DOUBLE;
895 case BOOLEAN:
896 return s.tag == BOOLEAN;
897 case VOID:
898 return false;
899 case BOT:
900 return isSubtype(t, s);
901 default:
902 throw new AssertionError();
903 }
904 }
906 @Override
907 public Boolean visitWildcardType(WildcardType t, Type s) {
908 return isCastable(upperBound(t), s, warnStack.head);
909 }
911 @Override
912 public Boolean visitClassType(ClassType t, Type s) {
913 if (s.tag == ERROR || s.tag == BOT)
914 return true;
916 if (s.tag == TYPEVAR) {
917 if (isCastable(s.getUpperBound(), t, Warner.noWarnings)) {
918 warnStack.head.warnUnchecked();
919 return true;
920 } else {
921 return false;
922 }
923 }
925 if (t.isCompound()) {
926 if (!visit(supertype(t), s))
927 return false;
928 for (Type intf : interfaces(t)) {
929 if (!visit(intf, s))
930 return false;
931 }
932 return true;
933 }
935 if (s.isCompound()) {
936 // call recursively to reuse the above code
937 return visitClassType((ClassType)s, t);
938 }
940 if (s.tag == CLASS || s.tag == ARRAY) {
941 boolean upcast;
942 if ((upcast = isSubtype(erasure(t), erasure(s)))
943 || isSubtype(erasure(s), erasure(t))) {
944 if (!upcast && s.tag == ARRAY) {
945 if (!isReifiable(s))
946 warnStack.head.warnUnchecked();
947 return true;
948 } else if (s.isRaw()) {
949 return true;
950 } else if (t.isRaw()) {
951 if (!isUnbounded(s))
952 warnStack.head.warnUnchecked();
953 return true;
954 }
955 // Assume |a| <: |b|
956 final Type a = upcast ? t : s;
957 final Type b = upcast ? s : t;
958 final boolean HIGH = true;
959 final boolean LOW = false;
960 final boolean DONT_REWRITE_TYPEVARS = false;
961 Type aHigh = rewriteQuantifiers(a, HIGH, DONT_REWRITE_TYPEVARS);
962 Type aLow = rewriteQuantifiers(a, LOW, DONT_REWRITE_TYPEVARS);
963 Type bHigh = rewriteQuantifiers(b, HIGH, DONT_REWRITE_TYPEVARS);
964 Type bLow = rewriteQuantifiers(b, LOW, DONT_REWRITE_TYPEVARS);
965 Type lowSub = asSub(bLow, aLow.tsym);
966 Type highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
967 if (highSub == null) {
968 final boolean REWRITE_TYPEVARS = true;
969 aHigh = rewriteQuantifiers(a, HIGH, REWRITE_TYPEVARS);
970 aLow = rewriteQuantifiers(a, LOW, REWRITE_TYPEVARS);
971 bHigh = rewriteQuantifiers(b, HIGH, REWRITE_TYPEVARS);
972 bLow = rewriteQuantifiers(b, LOW, REWRITE_TYPEVARS);
973 lowSub = asSub(bLow, aLow.tsym);
974 highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
975 }
976 if (highSub != null) {
977 assert a.tsym == highSub.tsym && a.tsym == lowSub.tsym
978 : a.tsym + " != " + highSub.tsym + " != " + lowSub.tsym;
979 if (!disjointTypes(aHigh.getTypeArguments(), highSub.getTypeArguments())
980 && !disjointTypes(aHigh.getTypeArguments(), lowSub.getTypeArguments())
981 && !disjointTypes(aLow.getTypeArguments(), highSub.getTypeArguments())
982 && !disjointTypes(aLow.getTypeArguments(), lowSub.getTypeArguments())) {
983 if (upcast ? giveWarning(a, highSub) || giveWarning(a, lowSub)
984 : giveWarning(highSub, a) || giveWarning(lowSub, a))
985 warnStack.head.warnUnchecked();
986 return true;
987 }
988 }
989 if (isReifiable(s))
990 return isSubtypeUnchecked(a, b);
991 else
992 return isSubtypeUnchecked(a, b, warnStack.head);
993 }
995 // Sidecast
996 if (s.tag == CLASS) {
997 if ((s.tsym.flags() & INTERFACE) != 0) {
998 return ((t.tsym.flags() & FINAL) == 0)
999 ? sideCast(t, s, warnStack.head)
1000 : sideCastFinal(t, s, warnStack.head);
1001 } else if ((t.tsym.flags() & INTERFACE) != 0) {
1002 return ((s.tsym.flags() & FINAL) == 0)
1003 ? sideCast(t, s, warnStack.head)
1004 : sideCastFinal(t, s, warnStack.head);
1005 } else {
1006 // unrelated class types
1007 return false;
1008 }
1009 }
1010 }
1011 return false;
1012 }
1014 @Override
1015 public Boolean visitArrayType(ArrayType t, Type s) {
1016 switch (s.tag) {
1017 case ERROR:
1018 case BOT:
1019 return true;
1020 case TYPEVAR:
1021 if (isCastable(s, t, Warner.noWarnings)) {
1022 warnStack.head.warnUnchecked();
1023 return true;
1024 } else {
1025 return false;
1026 }
1027 case CLASS:
1028 return isSubtype(t, s);
1029 case ARRAY:
1030 if (elemtype(t).tag <= lastBaseTag) {
1031 return elemtype(t).tag == elemtype(s).tag;
1032 } else {
1033 return visit(elemtype(t), elemtype(s));
1034 }
1035 default:
1036 return false;
1037 }
1038 }
1040 @Override
1041 public Boolean visitTypeVar(TypeVar t, Type s) {
1042 switch (s.tag) {
1043 case ERROR:
1044 case BOT:
1045 return true;
1046 case TYPEVAR:
1047 if (isSubtype(t, s)) {
1048 return true;
1049 } else if (isCastable(t.bound, s, Warner.noWarnings)) {
1050 warnStack.head.warnUnchecked();
1051 return true;
1052 } else {
1053 return false;
1054 }
1055 default:
1056 return isCastable(t.bound, s, warnStack.head);
1057 }
1058 }
1060 @Override
1061 public Boolean visitErrorType(ErrorType t, Type s) {
1062 return true;
1063 }
1064 };
1065 // </editor-fold>
1067 // <editor-fold defaultstate="collapsed" desc="disjointTypes">
1068 public boolean disjointTypes(List<Type> ts, List<Type> ss) {
1069 while (ts.tail != null && ss.tail != null) {
1070 if (disjointType(ts.head, ss.head)) return true;
1071 ts = ts.tail;
1072 ss = ss.tail;
1073 }
1074 return false;
1075 }
1077 /**
1078 * Two types or wildcards are considered disjoint if it can be
1079 * proven that no type can be contained in both. It is
1080 * conservative in that it is allowed to say that two types are
1081 * not disjoint, even though they actually are.
1082 *
1083 * The type C<X> is castable to C<Y> exactly if X and Y are not
1084 * disjoint.
1085 */
1086 public boolean disjointType(Type t, Type s) {
1087 return disjointType.visit(t, s);
1088 }
1089 // where
1090 private TypeRelation disjointType = new TypeRelation() {
1092 private Set<TypePair> cache = new HashSet<TypePair>();
1094 public Boolean visitType(Type t, Type s) {
1095 if (s.tag == WILDCARD)
1096 return visit(s, t);
1097 else
1098 return notSoftSubtypeRecursive(t, s) || notSoftSubtypeRecursive(s, t);
1099 }
1101 private boolean isCastableRecursive(Type t, Type s) {
1102 TypePair pair = new TypePair(t, s);
1103 if (cache.add(pair)) {
1104 try {
1105 return Types.this.isCastable(t, s);
1106 } finally {
1107 cache.remove(pair);
1108 }
1109 } else {
1110 return true;
1111 }
1112 }
1114 private boolean notSoftSubtypeRecursive(Type t, Type s) {
1115 TypePair pair = new TypePair(t, s);
1116 if (cache.add(pair)) {
1117 try {
1118 return Types.this.notSoftSubtype(t, s);
1119 } finally {
1120 cache.remove(pair);
1121 }
1122 } else {
1123 return false;
1124 }
1125 }
1127 @Override
1128 public Boolean visitWildcardType(WildcardType t, Type s) {
1129 if (t.isUnbound())
1130 return false;
1132 if (s.tag != WILDCARD) {
1133 if (t.isExtendsBound())
1134 return notSoftSubtypeRecursive(s, t.type);
1135 else // isSuperBound()
1136 return notSoftSubtypeRecursive(t.type, s);
1137 }
1139 if (s.isUnbound())
1140 return false;
1142 if (t.isExtendsBound()) {
1143 if (s.isExtendsBound())
1144 return !isCastableRecursive(t.type, upperBound(s));
1145 else if (s.isSuperBound())
1146 return notSoftSubtypeRecursive(lowerBound(s), t.type);
1147 } else if (t.isSuperBound()) {
1148 if (s.isExtendsBound())
1149 return notSoftSubtypeRecursive(t.type, upperBound(s));
1150 }
1151 return false;
1152 }
1153 };
1154 // </editor-fold>
1156 // <editor-fold defaultstate="collapsed" desc="lowerBoundArgtypes">
1157 /**
1158 * Returns the lower bounds of the formals of a method.
1159 */
1160 public List<Type> lowerBoundArgtypes(Type t) {
1161 return map(t.getParameterTypes(), lowerBoundMapping);
1162 }
1163 private final Mapping lowerBoundMapping = new Mapping("lowerBound") {
1164 public Type apply(Type t) {
1165 return lowerBound(t);
1166 }
1167 };
1168 // </editor-fold>
1170 // <editor-fold defaultstate="collapsed" desc="notSoftSubtype">
1171 /**
1172 * This relation answers the question: is impossible that
1173 * something of type `t' can be a subtype of `s'? This is
1174 * different from the question "is `t' not a subtype of `s'?"
1175 * when type variables are involved: Integer is not a subtype of T
1176 * where <T extends Number> but it is not true that Integer cannot
1177 * possibly be a subtype of T.
1178 */
1179 public boolean notSoftSubtype(Type t, Type s) {
1180 if (t == s) return false;
1181 if (t.tag == TYPEVAR) {
1182 TypeVar tv = (TypeVar) t;
1183 if (s.tag == TYPEVAR)
1184 s = s.getUpperBound();
1185 return !isCastable(tv.bound,
1186 s,
1187 Warner.noWarnings);
1188 }
1189 if (s.tag != WILDCARD)
1190 s = upperBound(s);
1191 if (s.tag == TYPEVAR)
1192 s = s.getUpperBound();
1193 return !isSubtype(t, s);
1194 }
1195 // </editor-fold>
1197 // <editor-fold defaultstate="collapsed" desc="isReifiable">
1198 public boolean isReifiable(Type t) {
1199 return isReifiable.visit(t);
1200 }
1201 // where
1202 private UnaryVisitor<Boolean> isReifiable = new UnaryVisitor<Boolean>() {
1204 public Boolean visitType(Type t, Void ignored) {
1205 return true;
1206 }
1208 @Override
1209 public Boolean visitClassType(ClassType t, Void ignored) {
1210 if (!t.isParameterized())
1211 return true;
1213 for (Type param : t.allparams()) {
1214 if (!param.isUnbound())
1215 return false;
1216 }
1217 return true;
1218 }
1220 @Override
1221 public Boolean visitArrayType(ArrayType t, Void ignored) {
1222 return visit(t.elemtype);
1223 }
1225 @Override
1226 public Boolean visitTypeVar(TypeVar t, Void ignored) {
1227 return false;
1228 }
1229 };
1230 // </editor-fold>
1232 // <editor-fold defaultstate="collapsed" desc="Array Utils">
1233 public boolean isArray(Type t) {
1234 while (t.tag == WILDCARD)
1235 t = upperBound(t);
1236 return t.tag == ARRAY;
1237 }
1239 /**
1240 * The element type of an array.
1241 */
1242 public Type elemtype(Type t) {
1243 switch (t.tag) {
1244 case WILDCARD:
1245 return elemtype(upperBound(t));
1246 case ARRAY:
1247 return ((ArrayType)t).elemtype;
1248 case FORALL:
1249 return elemtype(((ForAll)t).qtype);
1250 case ERROR:
1251 return t;
1252 default:
1253 return null;
1254 }
1255 }
1257 /**
1258 * Mapping to take element type of an arraytype
1259 */
1260 private Mapping elemTypeFun = new Mapping ("elemTypeFun") {
1261 public Type apply(Type t) { return elemtype(t); }
1262 };
1264 /**
1265 * The number of dimensions of an array type.
1266 */
1267 public int dimensions(Type t) {
1268 int result = 0;
1269 while (t.tag == ARRAY) {
1270 result++;
1271 t = elemtype(t);
1272 }
1273 return result;
1274 }
1275 // </editor-fold>
1277 // <editor-fold defaultstate="collapsed" desc="asSuper">
1278 /**
1279 * Return the (most specific) base type of t that starts with the
1280 * given symbol. If none exists, return null.
1281 *
1282 * @param t a type
1283 * @param sym a symbol
1284 */
1285 public Type asSuper(Type t, Symbol sym) {
1286 return asSuper.visit(t, sym);
1287 }
1288 // where
1289 private SimpleVisitor<Type,Symbol> asSuper = new SimpleVisitor<Type,Symbol>() {
1291 public Type visitType(Type t, Symbol sym) {
1292 return null;
1293 }
1295 @Override
1296 public Type visitClassType(ClassType t, Symbol sym) {
1297 if (t.tsym == sym)
1298 return t;
1300 Type st = supertype(t);
1301 if (st.tag == CLASS || st.tag == ERROR) {
1302 Type x = asSuper(st, sym);
1303 if (x != null)
1304 return x;
1305 }
1306 if ((sym.flags() & INTERFACE) != 0) {
1307 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
1308 Type x = asSuper(l.head, sym);
1309 if (x != null)
1310 return x;
1311 }
1312 }
1313 return null;
1314 }
1316 @Override
1317 public Type visitArrayType(ArrayType t, Symbol sym) {
1318 return isSubtype(t, sym.type) ? sym.type : null;
1319 }
1321 @Override
1322 public Type visitTypeVar(TypeVar t, Symbol sym) {
1323 return asSuper(t.bound, sym);
1324 }
1326 @Override
1327 public Type visitErrorType(ErrorType t, Symbol sym) {
1328 return t;
1329 }
1330 };
1332 /**
1333 * Return the base type of t or any of its outer types that starts
1334 * with the given symbol. If none exists, return null.
1335 *
1336 * @param t a type
1337 * @param sym a symbol
1338 */
1339 public Type asOuterSuper(Type t, Symbol sym) {
1340 switch (t.tag) {
1341 case CLASS:
1342 do {
1343 Type s = asSuper(t, sym);
1344 if (s != null) return s;
1345 t = t.getEnclosingType();
1346 } while (t.tag == CLASS);
1347 return null;
1348 case ARRAY:
1349 return isSubtype(t, sym.type) ? sym.type : null;
1350 case TYPEVAR:
1351 return asSuper(t, sym);
1352 case ERROR:
1353 return t;
1354 default:
1355 return null;
1356 }
1357 }
1359 /**
1360 * Return the base type of t or any of its enclosing types that
1361 * starts with the given symbol. If none exists, return null.
1362 *
1363 * @param t a type
1364 * @param sym a symbol
1365 */
1366 public Type asEnclosingSuper(Type t, Symbol sym) {
1367 switch (t.tag) {
1368 case CLASS:
1369 do {
1370 Type s = asSuper(t, sym);
1371 if (s != null) return s;
1372 Type outer = t.getEnclosingType();
1373 t = (outer.tag == CLASS) ? outer :
1374 (t.tsym.owner.enclClass() != null) ? t.tsym.owner.enclClass().type :
1375 Type.noType;
1376 } while (t.tag == CLASS);
1377 return null;
1378 case ARRAY:
1379 return isSubtype(t, sym.type) ? sym.type : null;
1380 case TYPEVAR:
1381 return asSuper(t, sym);
1382 case ERROR:
1383 return t;
1384 default:
1385 return null;
1386 }
1387 }
1388 // </editor-fold>
1390 // <editor-fold defaultstate="collapsed" desc="memberType">
1391 /**
1392 * The type of given symbol, seen as a member of t.
1393 *
1394 * @param t a type
1395 * @param sym a symbol
1396 */
1397 public Type memberType(Type t, Symbol sym) {
1398 return (sym.flags() & STATIC) != 0
1399 ? sym.type
1400 : memberType.visit(t, sym);
1401 }
1402 // where
1403 private SimpleVisitor<Type,Symbol> memberType = new SimpleVisitor<Type,Symbol>() {
1405 public Type visitType(Type t, Symbol sym) {
1406 return sym.type;
1407 }
1409 @Override
1410 public Type visitWildcardType(WildcardType t, Symbol sym) {
1411 return memberType(upperBound(t), sym);
1412 }
1414 @Override
1415 public Type visitClassType(ClassType t, Symbol sym) {
1416 Symbol owner = sym.owner;
1417 long flags = sym.flags();
1418 if (((flags & STATIC) == 0) && owner.type.isParameterized()) {
1419 Type base = asOuterSuper(t, owner);
1420 if (base != null) {
1421 List<Type> ownerParams = owner.type.allparams();
1422 List<Type> baseParams = base.allparams();
1423 if (ownerParams.nonEmpty()) {
1424 if (baseParams.isEmpty()) {
1425 // then base is a raw type
1426 return erasure(sym.type);
1427 } else {
1428 return subst(sym.type, ownerParams, baseParams);
1429 }
1430 }
1431 }
1432 }
1433 return sym.type;
1434 }
1436 @Override
1437 public Type visitTypeVar(TypeVar t, Symbol sym) {
1438 return memberType(t.bound, sym);
1439 }
1441 @Override
1442 public Type visitErrorType(ErrorType t, Symbol sym) {
1443 return t;
1444 }
1445 };
1446 // </editor-fold>
1448 // <editor-fold defaultstate="collapsed" desc="isAssignable">
1449 public boolean isAssignable(Type t, Type s) {
1450 return isAssignable(t, s, Warner.noWarnings);
1451 }
1453 /**
1454 * Is t assignable to s?<br>
1455 * Equivalent to subtype except for constant values and raw
1456 * types.<br>
1457 * (not defined for Method and ForAll types)
1458 */
1459 public boolean isAssignable(Type t, Type s, Warner warn) {
1460 if (t.tag == ERROR)
1461 return true;
1462 if (t.tag <= INT && t.constValue() != null) {
1463 int value = ((Number)t.constValue()).intValue();
1464 switch (s.tag) {
1465 case BYTE:
1466 if (Byte.MIN_VALUE <= value && value <= Byte.MAX_VALUE)
1467 return true;
1468 break;
1469 case CHAR:
1470 if (Character.MIN_VALUE <= value && value <= Character.MAX_VALUE)
1471 return true;
1472 break;
1473 case SHORT:
1474 if (Short.MIN_VALUE <= value && value <= Short.MAX_VALUE)
1475 return true;
1476 break;
1477 case INT:
1478 return true;
1479 case CLASS:
1480 switch (unboxedType(s).tag) {
1481 case BYTE:
1482 case CHAR:
1483 case SHORT:
1484 return isAssignable(t, unboxedType(s), warn);
1485 }
1486 break;
1487 }
1488 }
1489 return isConvertible(t, s, warn);
1490 }
1491 // </editor-fold>
1493 // <editor-fold defaultstate="collapsed" desc="erasure">
1494 /**
1495 * The erasure of t {@code |t|} -- the type that results when all
1496 * type parameters in t are deleted.
1497 */
1498 public Type erasure(Type t) {
1499 if (t.tag <= lastBaseTag)
1500 return t; /* fast special case */
1501 else
1502 return erasure.visit(t);
1503 }
1504 // where
1505 private UnaryVisitor<Type> erasure = new UnaryVisitor<Type>() {
1506 public Type visitType(Type t, Void ignored) {
1507 if (t.tag <= lastBaseTag)
1508 return t; /*fast special case*/
1509 else
1510 return t.map(erasureFun);
1511 }
1513 @Override
1514 public Type visitWildcardType(WildcardType t, Void ignored) {
1515 return erasure(upperBound(t));
1516 }
1518 @Override
1519 public Type visitClassType(ClassType t, Void ignored) {
1520 return t.tsym.erasure(Types.this);
1521 }
1523 @Override
1524 public Type visitTypeVar(TypeVar t, Void ignored) {
1525 return erasure(t.bound);
1526 }
1528 @Override
1529 public Type visitErrorType(ErrorType t, Void ignored) {
1530 return t;
1531 }
1532 };
1533 private Mapping erasureFun = new Mapping ("erasure") {
1534 public Type apply(Type t) { return erasure(t); }
1535 };
1537 public List<Type> erasure(List<Type> ts) {
1538 return Type.map(ts, erasureFun);
1539 }
1540 // </editor-fold>
1542 // <editor-fold defaultstate="collapsed" desc="makeCompoundType">
1543 /**
1544 * Make a compound type from non-empty list of types
1545 *
1546 * @param bounds the types from which the compound type is formed
1547 * @param supertype is objectType if all bounds are interfaces,
1548 * null otherwise.
1549 */
1550 public Type makeCompoundType(List<Type> bounds,
1551 Type supertype) {
1552 ClassSymbol bc =
1553 new ClassSymbol(ABSTRACT|PUBLIC|SYNTHETIC|COMPOUND|ACYCLIC,
1554 Type.moreInfo
1555 ? names.fromString(bounds.toString())
1556 : names.empty,
1557 syms.noSymbol);
1558 if (bounds.head.tag == TYPEVAR)
1559 // error condition, recover
1560 bc.erasure_field = syms.objectType;
1561 else
1562 bc.erasure_field = erasure(bounds.head);
1563 bc.members_field = new Scope(bc);
1564 ClassType bt = (ClassType)bc.type;
1565 bt.allparams_field = List.nil();
1566 if (supertype != null) {
1567 bt.supertype_field = supertype;
1568 bt.interfaces_field = bounds;
1569 } else {
1570 bt.supertype_field = bounds.head;
1571 bt.interfaces_field = bounds.tail;
1572 }
1573 assert bt.supertype_field.tsym.completer != null
1574 || !bt.supertype_field.isInterface()
1575 : bt.supertype_field;
1576 return bt;
1577 }
1579 /**
1580 * Same as {@link #makeCompoundType(List,Type)}, except that the
1581 * second parameter is computed directly. Note that this might
1582 * cause a symbol completion. Hence, this version of
1583 * makeCompoundType may not be called during a classfile read.
1584 */
1585 public Type makeCompoundType(List<Type> bounds) {
1586 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1587 supertype(bounds.head) : null;
1588 return makeCompoundType(bounds, supertype);
1589 }
1591 /**
1592 * A convenience wrapper for {@link #makeCompoundType(List)}; the
1593 * arguments are converted to a list and passed to the other
1594 * method. Note that this might cause a symbol completion.
1595 * Hence, this version of makeCompoundType may not be called
1596 * during a classfile read.
1597 */
1598 public Type makeCompoundType(Type bound1, Type bound2) {
1599 return makeCompoundType(List.of(bound1, bound2));
1600 }
1601 // </editor-fold>
1603 // <editor-fold defaultstate="collapsed" desc="supertype">
1604 public Type supertype(Type t) {
1605 return supertype.visit(t);
1606 }
1607 // where
1608 private UnaryVisitor<Type> supertype = new UnaryVisitor<Type>() {
1610 public Type visitType(Type t, Void ignored) {
1611 // A note on wildcards: there is no good way to
1612 // determine a supertype for a super bounded wildcard.
1613 return null;
1614 }
1616 @Override
1617 public Type visitClassType(ClassType t, Void ignored) {
1618 if (t.supertype_field == null) {
1619 Type supertype = ((ClassSymbol)t.tsym).getSuperclass();
1620 // An interface has no superclass; its supertype is Object.
1621 if (t.isInterface())
1622 supertype = ((ClassType)t.tsym.type).supertype_field;
1623 if (t.supertype_field == null) {
1624 List<Type> actuals = classBound(t).allparams();
1625 List<Type> formals = t.tsym.type.allparams();
1626 if (actuals.isEmpty()) {
1627 if (formals.isEmpty())
1628 // Should not happen. See comments below in interfaces
1629 t.supertype_field = supertype;
1630 else
1631 t.supertype_field = erasure(supertype);
1632 } else {
1633 t.supertype_field = subst(supertype, formals, actuals);
1634 }
1635 }
1636 }
1637 return t.supertype_field;
1638 }
1640 /**
1641 * The supertype is always a class type. If the type
1642 * variable's bounds start with a class type, this is also
1643 * the supertype. Otherwise, the supertype is
1644 * java.lang.Object.
1645 */
1646 @Override
1647 public Type visitTypeVar(TypeVar t, Void ignored) {
1648 if (t.bound.tag == TYPEVAR ||
1649 (!t.bound.isCompound() && !t.bound.isInterface())) {
1650 return t.bound;
1651 } else {
1652 return supertype(t.bound);
1653 }
1654 }
1656 @Override
1657 public Type visitArrayType(ArrayType t, Void ignored) {
1658 if (t.elemtype.isPrimitive() || isSameType(t.elemtype, syms.objectType))
1659 return arraySuperType();
1660 else
1661 return new ArrayType(supertype(t.elemtype), t.tsym);
1662 }
1664 @Override
1665 public Type visitErrorType(ErrorType t, Void ignored) {
1666 return t;
1667 }
1668 };
1669 // </editor-fold>
1671 // <editor-fold defaultstate="collapsed" desc="interfaces">
1672 /**
1673 * Return the interfaces implemented by this class.
1674 */
1675 public List<Type> interfaces(Type t) {
1676 return interfaces.visit(t);
1677 }
1678 // where
1679 private UnaryVisitor<List<Type>> interfaces = new UnaryVisitor<List<Type>>() {
1681 public List<Type> visitType(Type t, Void ignored) {
1682 return List.nil();
1683 }
1685 @Override
1686 public List<Type> visitClassType(ClassType t, Void ignored) {
1687 if (t.interfaces_field == null) {
1688 List<Type> interfaces = ((ClassSymbol)t.tsym).getInterfaces();
1689 if (t.interfaces_field == null) {
1690 // If t.interfaces_field is null, then t must
1691 // be a parameterized type (not to be confused
1692 // with a generic type declaration).
1693 // Terminology:
1694 // Parameterized type: List<String>
1695 // Generic type declaration: class List<E> { ... }
1696 // So t corresponds to List<String> and
1697 // t.tsym.type corresponds to List<E>.
1698 // The reason t must be parameterized type is
1699 // that completion will happen as a side
1700 // effect of calling
1701 // ClassSymbol.getInterfaces. Since
1702 // t.interfaces_field is null after
1703 // completion, we can assume that t is not the
1704 // type of a class/interface declaration.
1705 assert t != t.tsym.type : t.toString();
1706 List<Type> actuals = t.allparams();
1707 List<Type> formals = t.tsym.type.allparams();
1708 if (actuals.isEmpty()) {
1709 if (formals.isEmpty()) {
1710 // In this case t is not generic (nor raw).
1711 // So this should not happen.
1712 t.interfaces_field = interfaces;
1713 } else {
1714 t.interfaces_field = erasure(interfaces);
1715 }
1716 } else {
1717 t.interfaces_field =
1718 upperBounds(subst(interfaces, formals, actuals));
1719 }
1720 }
1721 }
1722 return t.interfaces_field;
1723 }
1725 @Override
1726 public List<Type> visitTypeVar(TypeVar t, Void ignored) {
1727 if (t.bound.isCompound())
1728 return interfaces(t.bound);
1730 if (t.bound.isInterface())
1731 return List.of(t.bound);
1733 return List.nil();
1734 }
1735 };
1736 // </editor-fold>
1738 // <editor-fold defaultstate="collapsed" desc="isDerivedRaw">
1739 Map<Type,Boolean> isDerivedRawCache = new HashMap<Type,Boolean>();
1741 public boolean isDerivedRaw(Type t) {
1742 Boolean result = isDerivedRawCache.get(t);
1743 if (result == null) {
1744 result = isDerivedRawInternal(t);
1745 isDerivedRawCache.put(t, result);
1746 }
1747 return result;
1748 }
1750 public boolean isDerivedRawInternal(Type t) {
1751 if (t.isErroneous())
1752 return false;
1753 return
1754 t.isRaw() ||
1755 supertype(t) != null && isDerivedRaw(supertype(t)) ||
1756 isDerivedRaw(interfaces(t));
1757 }
1759 public boolean isDerivedRaw(List<Type> ts) {
1760 List<Type> l = ts;
1761 while (l.nonEmpty() && !isDerivedRaw(l.head)) l = l.tail;
1762 return l.nonEmpty();
1763 }
1764 // </editor-fold>
1766 // <editor-fold defaultstate="collapsed" desc="setBounds">
1767 /**
1768 * Set the bounds field of the given type variable to reflect a
1769 * (possibly multiple) list of bounds.
1770 * @param t a type variable
1771 * @param bounds the bounds, must be nonempty
1772 * @param supertype is objectType if all bounds are interfaces,
1773 * null otherwise.
1774 */
1775 public void setBounds(TypeVar t, List<Type> bounds, Type supertype) {
1776 if (bounds.tail.isEmpty())
1777 t.bound = bounds.head;
1778 else
1779 t.bound = makeCompoundType(bounds, supertype);
1780 t.rank_field = -1;
1781 }
1783 /**
1784 * Same as {@link #setBounds(Type.TypeVar,List,Type)}, except that
1785 * third parameter is computed directly. Note that this test
1786 * might cause a symbol completion. Hence, this version of
1787 * setBounds may not be called during a classfile read.
1788 */
1789 public void setBounds(TypeVar t, List<Type> bounds) {
1790 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1791 supertype(bounds.head) : null;
1792 setBounds(t, bounds, supertype);
1793 t.rank_field = -1;
1794 }
1795 // </editor-fold>
1797 // <editor-fold defaultstate="collapsed" desc="getBounds">
1798 /**
1799 * Return list of bounds of the given type variable.
1800 */
1801 public List<Type> getBounds(TypeVar t) {
1802 if (t.bound.isErroneous() || !t.bound.isCompound())
1803 return List.of(t.bound);
1804 else if ((erasure(t).tsym.flags() & INTERFACE) == 0)
1805 return interfaces(t).prepend(supertype(t));
1806 else
1807 // No superclass was given in bounds.
1808 // In this case, supertype is Object, erasure is first interface.
1809 return interfaces(t);
1810 }
1811 // </editor-fold>
1813 // <editor-fold defaultstate="collapsed" desc="classBound">
1814 /**
1815 * If the given type is a (possibly selected) type variable,
1816 * return the bounding class of this type, otherwise return the
1817 * type itself.
1818 */
1819 public Type classBound(Type t) {
1820 return classBound.visit(t);
1821 }
1822 // where
1823 private UnaryVisitor<Type> classBound = new UnaryVisitor<Type>() {
1825 public Type visitType(Type t, Void ignored) {
1826 return t;
1827 }
1829 @Override
1830 public Type visitClassType(ClassType t, Void ignored) {
1831 Type outer1 = classBound(t.getEnclosingType());
1832 if (outer1 != t.getEnclosingType())
1833 return new ClassType(outer1, t.getTypeArguments(), t.tsym);
1834 else
1835 return t;
1836 }
1838 @Override
1839 public Type visitTypeVar(TypeVar t, Void ignored) {
1840 return classBound(supertype(t));
1841 }
1843 @Override
1844 public Type visitErrorType(ErrorType t, Void ignored) {
1845 return t;
1846 }
1847 };
1848 // </editor-fold>
1850 // <editor-fold defaultstate="collapsed" desc="sub signature / override equivalence">
1851 /**
1852 * Returns true iff the first signature is a <em>sub
1853 * signature</em> of the other. This is <b>not</b> an equivalence
1854 * relation.
1855 *
1856 * @see "The Java Language Specification, Third Ed. (8.4.2)."
1857 * @see #overrideEquivalent(Type t, Type s)
1858 * @param t first signature (possibly raw).
1859 * @param s second signature (could be subjected to erasure).
1860 * @return true if t is a sub signature of s.
1861 */
1862 public boolean isSubSignature(Type t, Type s) {
1863 return hasSameArgs(t, s) || hasSameArgs(t, erasure(s));
1864 }
1866 /**
1867 * Returns true iff these signatures are related by <em>override
1868 * equivalence</em>. This is the natural extension of
1869 * isSubSignature to an equivalence relation.
1870 *
1871 * @see "The Java Language Specification, Third Ed. (8.4.2)."
1872 * @see #isSubSignature(Type t, Type s)
1873 * @param t a signature (possible raw, could be subjected to
1874 * erasure).
1875 * @param s a signature (possible raw, could be subjected to
1876 * erasure).
1877 * @return true if either argument is a sub signature of the other.
1878 */
1879 public boolean overrideEquivalent(Type t, Type s) {
1880 return hasSameArgs(t, s) ||
1881 hasSameArgs(t, erasure(s)) || hasSameArgs(erasure(t), s);
1882 }
1884 /**
1885 * Does t have the same arguments as s? It is assumed that both
1886 * types are (possibly polymorphic) method types. Monomorphic
1887 * method types "have the same arguments", if their argument lists
1888 * are equal. Polymorphic method types "have the same arguments",
1889 * if they have the same arguments after renaming all type
1890 * variables of one to corresponding type variables in the other,
1891 * where correspondence is by position in the type parameter list.
1892 */
1893 public boolean hasSameArgs(Type t, Type s) {
1894 return hasSameArgs.visit(t, s);
1895 }
1896 // where
1897 private TypeRelation hasSameArgs = new TypeRelation() {
1899 public Boolean visitType(Type t, Type s) {
1900 throw new AssertionError();
1901 }
1903 @Override
1904 public Boolean visitMethodType(MethodType t, Type s) {
1905 return s.tag == METHOD
1906 && containsTypeEquivalent(t.argtypes, s.getParameterTypes());
1907 }
1909 @Override
1910 public Boolean visitForAll(ForAll t, Type s) {
1911 if (s.tag != FORALL)
1912 return false;
1914 ForAll forAll = (ForAll)s;
1915 return hasSameBounds(t, forAll)
1916 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
1917 }
1919 @Override
1920 public Boolean visitErrorType(ErrorType t, Type s) {
1921 return false;
1922 }
1923 };
1924 // </editor-fold>
1926 // <editor-fold defaultstate="collapsed" desc="subst">
1927 public List<Type> subst(List<Type> ts,
1928 List<Type> from,
1929 List<Type> to) {
1930 return new Subst(from, to).subst(ts);
1931 }
1933 /**
1934 * Substitute all occurrences of a type in `from' with the
1935 * corresponding type in `to' in 't'. Match lists `from' and `to'
1936 * from the right: If lists have different length, discard leading
1937 * elements of the longer list.
1938 */
1939 public Type subst(Type t, List<Type> from, List<Type> to) {
1940 return new Subst(from, to).subst(t);
1941 }
1943 private class Subst extends UnaryVisitor<Type> {
1944 List<Type> from;
1945 List<Type> to;
1947 public Subst(List<Type> from, List<Type> to) {
1948 int fromLength = from.length();
1949 int toLength = to.length();
1950 while (fromLength > toLength) {
1951 fromLength--;
1952 from = from.tail;
1953 }
1954 while (fromLength < toLength) {
1955 toLength--;
1956 to = to.tail;
1957 }
1958 this.from = from;
1959 this.to = to;
1960 }
1962 Type subst(Type t) {
1963 if (from.tail == null)
1964 return t;
1965 else
1966 return visit(t);
1967 }
1969 List<Type> subst(List<Type> ts) {
1970 if (from.tail == null)
1971 return ts;
1972 boolean wild = false;
1973 if (ts.nonEmpty() && from.nonEmpty()) {
1974 Type head1 = subst(ts.head);
1975 List<Type> tail1 = subst(ts.tail);
1976 if (head1 != ts.head || tail1 != ts.tail)
1977 return tail1.prepend(head1);
1978 }
1979 return ts;
1980 }
1982 public Type visitType(Type t, Void ignored) {
1983 return t;
1984 }
1986 @Override
1987 public Type visitMethodType(MethodType t, Void ignored) {
1988 List<Type> argtypes = subst(t.argtypes);
1989 Type restype = subst(t.restype);
1990 List<Type> thrown = subst(t.thrown);
1991 if (argtypes == t.argtypes &&
1992 restype == t.restype &&
1993 thrown == t.thrown)
1994 return t;
1995 else
1996 return new MethodType(argtypes, restype, thrown, t.tsym);
1997 }
1999 @Override
2000 public Type visitTypeVar(TypeVar t, Void ignored) {
2001 for (List<Type> from = this.from, to = this.to;
2002 from.nonEmpty();
2003 from = from.tail, to = to.tail) {
2004 if (t == from.head) {
2005 return to.head.withTypeVar(t);
2006 }
2007 }
2008 return t;
2009 }
2011 @Override
2012 public Type visitClassType(ClassType t, Void ignored) {
2013 if (!t.isCompound()) {
2014 List<Type> typarams = t.getTypeArguments();
2015 List<Type> typarams1 = subst(typarams);
2016 Type outer = t.getEnclosingType();
2017 Type outer1 = subst(outer);
2018 if (typarams1 == typarams && outer1 == outer)
2019 return t;
2020 else
2021 return new ClassType(outer1, typarams1, t.tsym);
2022 } else {
2023 Type st = subst(supertype(t));
2024 List<Type> is = upperBounds(subst(interfaces(t)));
2025 if (st == supertype(t) && is == interfaces(t))
2026 return t;
2027 else
2028 return makeCompoundType(is.prepend(st));
2029 }
2030 }
2032 @Override
2033 public Type visitWildcardType(WildcardType t, Void ignored) {
2034 Type bound = t.type;
2035 if (t.kind != BoundKind.UNBOUND)
2036 bound = subst(bound);
2037 if (bound == t.type) {
2038 return t;
2039 } else {
2040 if (t.isExtendsBound() && bound.isExtendsBound())
2041 bound = upperBound(bound);
2042 return new WildcardType(bound, t.kind, syms.boundClass, t.bound);
2043 }
2044 }
2046 @Override
2047 public Type visitArrayType(ArrayType t, Void ignored) {
2048 Type elemtype = subst(t.elemtype);
2049 if (elemtype == t.elemtype)
2050 return t;
2051 else
2052 return new ArrayType(upperBound(elemtype), t.tsym);
2053 }
2055 @Override
2056 public Type visitForAll(ForAll t, Void ignored) {
2057 List<Type> tvars1 = substBounds(t.tvars, from, to);
2058 Type qtype1 = subst(t.qtype);
2059 if (tvars1 == t.tvars && qtype1 == t.qtype) {
2060 return t;
2061 } else if (tvars1 == t.tvars) {
2062 return new ForAll(tvars1, qtype1);
2063 } else {
2064 return new ForAll(tvars1, Types.this.subst(qtype1, t.tvars, tvars1));
2065 }
2066 }
2068 @Override
2069 public Type visitErrorType(ErrorType t, Void ignored) {
2070 return t;
2071 }
2072 }
2074 public List<Type> substBounds(List<Type> tvars,
2075 List<Type> from,
2076 List<Type> to) {
2077 if (tvars.isEmpty())
2078 return tvars;
2079 if (tvars.tail.isEmpty())
2080 // fast common case
2081 return List.<Type>of(substBound((TypeVar)tvars.head, from, to));
2082 ListBuffer<Type> newBoundsBuf = lb();
2083 boolean changed = false;
2084 // calculate new bounds
2085 for (Type t : tvars) {
2086 TypeVar tv = (TypeVar) t;
2087 Type bound = subst(tv.bound, from, to);
2088 if (bound != tv.bound)
2089 changed = true;
2090 newBoundsBuf.append(bound);
2091 }
2092 if (!changed)
2093 return tvars;
2094 ListBuffer<Type> newTvars = lb();
2095 // create new type variables without bounds
2096 for (Type t : tvars) {
2097 newTvars.append(new TypeVar(t.tsym, null, syms.botType));
2098 }
2099 // the new bounds should use the new type variables in place
2100 // of the old
2101 List<Type> newBounds = newBoundsBuf.toList();
2102 from = tvars;
2103 to = newTvars.toList();
2104 for (; !newBounds.isEmpty(); newBounds = newBounds.tail) {
2105 newBounds.head = subst(newBounds.head, from, to);
2106 }
2107 newBounds = newBoundsBuf.toList();
2108 // set the bounds of new type variables to the new bounds
2109 for (Type t : newTvars.toList()) {
2110 TypeVar tv = (TypeVar) t;
2111 tv.bound = newBounds.head;
2112 newBounds = newBounds.tail;
2113 }
2114 return newTvars.toList();
2115 }
2117 public TypeVar substBound(TypeVar t, List<Type> from, List<Type> to) {
2118 Type bound1 = subst(t.bound, from, to);
2119 if (bound1 == t.bound)
2120 return t;
2121 else
2122 return new TypeVar(t.tsym, bound1, syms.botType);
2123 }
2124 // </editor-fold>
2126 // <editor-fold defaultstate="collapsed" desc="hasSameBounds">
2127 /**
2128 * Does t have the same bounds for quantified variables as s?
2129 */
2130 boolean hasSameBounds(ForAll t, ForAll s) {
2131 List<Type> l1 = t.tvars;
2132 List<Type> l2 = s.tvars;
2133 while (l1.nonEmpty() && l2.nonEmpty() &&
2134 isSameType(l1.head.getUpperBound(),
2135 subst(l2.head.getUpperBound(),
2136 s.tvars,
2137 t.tvars))) {
2138 l1 = l1.tail;
2139 l2 = l2.tail;
2140 }
2141 return l1.isEmpty() && l2.isEmpty();
2142 }
2143 // </editor-fold>
2145 // <editor-fold defaultstate="collapsed" desc="newInstances">
2146 /** Create new vector of type variables from list of variables
2147 * changing all recursive bounds from old to new list.
2148 */
2149 public List<Type> newInstances(List<Type> tvars) {
2150 List<Type> tvars1 = Type.map(tvars, newInstanceFun);
2151 for (List<Type> l = tvars1; l.nonEmpty(); l = l.tail) {
2152 TypeVar tv = (TypeVar) l.head;
2153 tv.bound = subst(tv.bound, tvars, tvars1);
2154 }
2155 return tvars1;
2156 }
2157 static private Mapping newInstanceFun = new Mapping("newInstanceFun") {
2158 public Type apply(Type t) { return new TypeVar(t.tsym, t.getUpperBound(), t.getLowerBound()); }
2159 };
2160 // </editor-fold>
2162 // <editor-fold defaultstate="collapsed" desc="rank">
2163 /**
2164 * The rank of a class is the length of the longest path between
2165 * the class and java.lang.Object in the class inheritance
2166 * graph. Undefined for all but reference types.
2167 */
2168 public int rank(Type t) {
2169 switch(t.tag) {
2170 case CLASS: {
2171 ClassType cls = (ClassType)t;
2172 if (cls.rank_field < 0) {
2173 Name fullname = cls.tsym.getQualifiedName();
2174 if (fullname == fullname.table.java_lang_Object)
2175 cls.rank_field = 0;
2176 else {
2177 int r = rank(supertype(cls));
2178 for (List<Type> l = interfaces(cls);
2179 l.nonEmpty();
2180 l = l.tail) {
2181 if (rank(l.head) > r)
2182 r = rank(l.head);
2183 }
2184 cls.rank_field = r + 1;
2185 }
2186 }
2187 return cls.rank_field;
2188 }
2189 case TYPEVAR: {
2190 TypeVar tvar = (TypeVar)t;
2191 if (tvar.rank_field < 0) {
2192 int r = rank(supertype(tvar));
2193 for (List<Type> l = interfaces(tvar);
2194 l.nonEmpty();
2195 l = l.tail) {
2196 if (rank(l.head) > r) r = rank(l.head);
2197 }
2198 tvar.rank_field = r + 1;
2199 }
2200 return tvar.rank_field;
2201 }
2202 case ERROR:
2203 return 0;
2204 default:
2205 throw new AssertionError();
2206 }
2207 }
2208 // </editor-fold>
2210 // <editor-fold defaultstate="collapsed" desc="toString">
2211 /**
2212 * This toString is slightly more descriptive than the one on Type.
2213 */
2214 public String toString(Type t) {
2215 if (t.tag == FORALL) {
2216 ForAll forAll = (ForAll)t;
2217 return typaramsString(forAll.tvars) + forAll.qtype;
2218 }
2219 return "" + t;
2220 }
2221 // where
2222 private String typaramsString(List<Type> tvars) {
2223 StringBuffer s = new StringBuffer();
2224 s.append('<');
2225 boolean first = true;
2226 for (Type t : tvars) {
2227 if (!first) s.append(", ");
2228 first = false;
2229 appendTyparamString(((TypeVar)t), s);
2230 }
2231 s.append('>');
2232 return s.toString();
2233 }
2234 private void appendTyparamString(TypeVar t, StringBuffer buf) {
2235 buf.append(t);
2236 if (t.bound == null ||
2237 t.bound.tsym.getQualifiedName() == names.java_lang_Object)
2238 return;
2239 buf.append(" extends "); // Java syntax; no need for i18n
2240 Type bound = t.bound;
2241 if (!bound.isCompound()) {
2242 buf.append(bound);
2243 } else if ((erasure(t).tsym.flags() & INTERFACE) == 0) {
2244 buf.append(supertype(t));
2245 for (Type intf : interfaces(t)) {
2246 buf.append('&');
2247 buf.append(intf);
2248 }
2249 } else {
2250 // No superclass was given in bounds.
2251 // In this case, supertype is Object, erasure is first interface.
2252 boolean first = true;
2253 for (Type intf : interfaces(t)) {
2254 if (!first) buf.append('&');
2255 first = false;
2256 buf.append(intf);
2257 }
2258 }
2259 }
2260 // </editor-fold>
2262 // <editor-fold defaultstate="collapsed" desc="Determining least upper bounds of types">
2263 /**
2264 * A cache for closures.
2265 *
2266 * <p>A closure is a list of all the supertypes and interfaces of
2267 * a class or interface type, ordered by ClassSymbol.precedes
2268 * (that is, subclasses come first, arbitrary but fixed
2269 * otherwise).
2270 */
2271 private Map<Type,List<Type>> closureCache = new HashMap<Type,List<Type>>();
2273 /**
2274 * Returns the closure of a class or interface type.
2275 */
2276 public List<Type> closure(Type t) {
2277 List<Type> cl = closureCache.get(t);
2278 if (cl == null) {
2279 Type st = supertype(t);
2280 if (!t.isCompound()) {
2281 if (st.tag == CLASS) {
2282 cl = insert(closure(st), t);
2283 } else if (st.tag == TYPEVAR) {
2284 cl = closure(st).prepend(t);
2285 } else {
2286 cl = List.of(t);
2287 }
2288 } else {
2289 cl = closure(supertype(t));
2290 }
2291 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail)
2292 cl = union(cl, closure(l.head));
2293 closureCache.put(t, cl);
2294 }
2295 return cl;
2296 }
2298 /**
2299 * Insert a type in a closure
2300 */
2301 public List<Type> insert(List<Type> cl, Type t) {
2302 if (cl.isEmpty() || t.tsym.precedes(cl.head.tsym, this)) {
2303 return cl.prepend(t);
2304 } else if (cl.head.tsym.precedes(t.tsym, this)) {
2305 return insert(cl.tail, t).prepend(cl.head);
2306 } else {
2307 return cl;
2308 }
2309 }
2311 /**
2312 * Form the union of two closures
2313 */
2314 public List<Type> union(List<Type> cl1, List<Type> cl2) {
2315 if (cl1.isEmpty()) {
2316 return cl2;
2317 } else if (cl2.isEmpty()) {
2318 return cl1;
2319 } else if (cl1.head.tsym.precedes(cl2.head.tsym, this)) {
2320 return union(cl1.tail, cl2).prepend(cl1.head);
2321 } else if (cl2.head.tsym.precedes(cl1.head.tsym, this)) {
2322 return union(cl1, cl2.tail).prepend(cl2.head);
2323 } else {
2324 return union(cl1.tail, cl2.tail).prepend(cl1.head);
2325 }
2326 }
2328 /**
2329 * Intersect two closures
2330 */
2331 public List<Type> intersect(List<Type> cl1, List<Type> cl2) {
2332 if (cl1 == cl2)
2333 return cl1;
2334 if (cl1.isEmpty() || cl2.isEmpty())
2335 return List.nil();
2336 if (cl1.head.tsym.precedes(cl2.head.tsym, this))
2337 return intersect(cl1.tail, cl2);
2338 if (cl2.head.tsym.precedes(cl1.head.tsym, this))
2339 return intersect(cl1, cl2.tail);
2340 if (isSameType(cl1.head, cl2.head))
2341 return intersect(cl1.tail, cl2.tail).prepend(cl1.head);
2342 if (cl1.head.tsym == cl2.head.tsym &&
2343 cl1.head.tag == CLASS && cl2.head.tag == CLASS) {
2344 if (cl1.head.isParameterized() && cl2.head.isParameterized()) {
2345 Type merge = merge(cl1.head,cl2.head);
2346 return intersect(cl1.tail, cl2.tail).prepend(merge);
2347 }
2348 if (cl1.head.isRaw() || cl2.head.isRaw())
2349 return intersect(cl1.tail, cl2.tail).prepend(erasure(cl1.head));
2350 }
2351 return intersect(cl1.tail, cl2.tail);
2352 }
2353 // where
2354 class TypePair {
2355 final Type t1;
2356 final Type t2;
2357 TypePair(Type t1, Type t2) {
2358 this.t1 = t1;
2359 this.t2 = t2;
2360 }
2361 @Override
2362 public int hashCode() {
2363 return 127 * Types.this.hashCode(t1) + Types.this.hashCode(t2);
2364 }
2365 @Override
2366 public boolean equals(Object obj) {
2367 if (!(obj instanceof TypePair))
2368 return false;
2369 TypePair typePair = (TypePair)obj;
2370 return isSameType(t1, typePair.t1)
2371 && isSameType(t2, typePair.t2);
2372 }
2373 }
2374 Set<TypePair> mergeCache = new HashSet<TypePair>();
2375 private Type merge(Type c1, Type c2) {
2376 ClassType class1 = (ClassType) c1;
2377 List<Type> act1 = class1.getTypeArguments();
2378 ClassType class2 = (ClassType) c2;
2379 List<Type> act2 = class2.getTypeArguments();
2380 ListBuffer<Type> merged = new ListBuffer<Type>();
2381 List<Type> typarams = class1.tsym.type.getTypeArguments();
2383 while (act1.nonEmpty() && act2.nonEmpty() && typarams.nonEmpty()) {
2384 if (containsType(act1.head, act2.head)) {
2385 merged.append(act1.head);
2386 } else if (containsType(act2.head, act1.head)) {
2387 merged.append(act2.head);
2388 } else {
2389 TypePair pair = new TypePair(c1, c2);
2390 Type m;
2391 if (mergeCache.add(pair)) {
2392 m = new WildcardType(lub(upperBound(act1.head),
2393 upperBound(act2.head)),
2394 BoundKind.EXTENDS,
2395 syms.boundClass);
2396 mergeCache.remove(pair);
2397 } else {
2398 m = new WildcardType(syms.objectType,
2399 BoundKind.UNBOUND,
2400 syms.boundClass);
2401 }
2402 merged.append(m.withTypeVar(typarams.head));
2403 }
2404 act1 = act1.tail;
2405 act2 = act2.tail;
2406 typarams = typarams.tail;
2407 }
2408 assert(act1.isEmpty() && act2.isEmpty() && typarams.isEmpty());
2409 return new ClassType(class1.getEnclosingType(), merged.toList(), class1.tsym);
2410 }
2412 /**
2413 * Return the minimum type of a closure, a compound type if no
2414 * unique minimum exists.
2415 */
2416 private Type compoundMin(List<Type> cl) {
2417 if (cl.isEmpty()) return syms.objectType;
2418 List<Type> compound = closureMin(cl);
2419 if (compound.isEmpty())
2420 return null;
2421 else if (compound.tail.isEmpty())
2422 return compound.head;
2423 else
2424 return makeCompoundType(compound);
2425 }
2427 /**
2428 * Return the minimum types of a closure, suitable for computing
2429 * compoundMin or glb.
2430 */
2431 private List<Type> closureMin(List<Type> cl) {
2432 ListBuffer<Type> classes = lb();
2433 ListBuffer<Type> interfaces = lb();
2434 while (!cl.isEmpty()) {
2435 Type current = cl.head;
2436 if (current.isInterface())
2437 interfaces.append(current);
2438 else
2439 classes.append(current);
2440 ListBuffer<Type> candidates = lb();
2441 for (Type t : cl.tail) {
2442 if (!isSubtypeNoCapture(current, t))
2443 candidates.append(t);
2444 }
2445 cl = candidates.toList();
2446 }
2447 return classes.appendList(interfaces).toList();
2448 }
2450 /**
2451 * Return the least upper bound of pair of types. if the lub does
2452 * not exist return null.
2453 */
2454 public Type lub(Type t1, Type t2) {
2455 return lub(List.of(t1, t2));
2456 }
2458 /**
2459 * Return the least upper bound (lub) of set of types. If the lub
2460 * does not exist return the type of null (bottom).
2461 */
2462 public Type lub(List<Type> ts) {
2463 final int ARRAY_BOUND = 1;
2464 final int CLASS_BOUND = 2;
2465 int boundkind = 0;
2466 for (Type t : ts) {
2467 switch (t.tag) {
2468 case CLASS:
2469 boundkind |= CLASS_BOUND;
2470 break;
2471 case ARRAY:
2472 boundkind |= ARRAY_BOUND;
2473 break;
2474 case TYPEVAR:
2475 do {
2476 t = t.getUpperBound();
2477 } while (t.tag == TYPEVAR);
2478 if (t.tag == ARRAY) {
2479 boundkind |= ARRAY_BOUND;
2480 } else {
2481 boundkind |= CLASS_BOUND;
2482 }
2483 break;
2484 default:
2485 if (t.isPrimitive())
2486 return syms.botType;
2487 }
2488 }
2489 switch (boundkind) {
2490 case 0:
2491 return syms.botType;
2493 case ARRAY_BOUND:
2494 // calculate lub(A[], B[])
2495 List<Type> elements = Type.map(ts, elemTypeFun);
2496 for (Type t : elements) {
2497 if (t.isPrimitive()) {
2498 // if a primitive type is found, then return
2499 // arraySuperType unless all the types are the
2500 // same
2501 Type first = ts.head;
2502 for (Type s : ts.tail) {
2503 if (!isSameType(first, s)) {
2504 // lub(int[], B[]) is Cloneable & Serializable
2505 return arraySuperType();
2506 }
2507 }
2508 // all the array types are the same, return one
2509 // lub(int[], int[]) is int[]
2510 return first;
2511 }
2512 }
2513 // lub(A[], B[]) is lub(A, B)[]
2514 return new ArrayType(lub(elements), syms.arrayClass);
2516 case CLASS_BOUND:
2517 // calculate lub(A, B)
2518 while (ts.head.tag != CLASS && ts.head.tag != TYPEVAR)
2519 ts = ts.tail;
2520 assert !ts.isEmpty();
2521 List<Type> cl = closure(ts.head);
2522 for (Type t : ts.tail) {
2523 if (t.tag == CLASS || t.tag == TYPEVAR)
2524 cl = intersect(cl, closure(t));
2525 }
2526 return compoundMin(cl);
2528 default:
2529 // calculate lub(A, B[])
2530 List<Type> classes = List.of(arraySuperType());
2531 for (Type t : ts) {
2532 if (t.tag != ARRAY) // Filter out any arrays
2533 classes = classes.prepend(t);
2534 }
2535 // lub(A, B[]) is lub(A, arraySuperType)
2536 return lub(classes);
2537 }
2538 }
2539 // where
2540 private Type arraySuperType = null;
2541 private Type arraySuperType() {
2542 // initialized lazily to avoid problems during compiler startup
2543 if (arraySuperType == null) {
2544 synchronized (this) {
2545 if (arraySuperType == null) {
2546 // JLS 10.8: all arrays implement Cloneable and Serializable.
2547 arraySuperType = makeCompoundType(List.of(syms.serializableType,
2548 syms.cloneableType),
2549 syms.objectType);
2550 }
2551 }
2552 }
2553 return arraySuperType;
2554 }
2555 // </editor-fold>
2557 // <editor-fold defaultstate="collapsed" desc="Greatest lower bound">
2558 public Type glb(Type t, Type s) {
2559 if (s == null)
2560 return t;
2561 else if (isSubtypeNoCapture(t, s))
2562 return t;
2563 else if (isSubtypeNoCapture(s, t))
2564 return s;
2566 List<Type> closure = union(closure(t), closure(s));
2567 List<Type> bounds = closureMin(closure);
2569 if (bounds.isEmpty()) { // length == 0
2570 return syms.objectType;
2571 } else if (bounds.tail.isEmpty()) { // length == 1
2572 return bounds.head;
2573 } else { // length > 1
2574 int classCount = 0;
2575 for (Type bound : bounds)
2576 if (!bound.isInterface())
2577 classCount++;
2578 if (classCount > 1)
2579 return syms.errType;
2580 }
2581 return makeCompoundType(bounds);
2582 }
2583 // </editor-fold>
2585 // <editor-fold defaultstate="collapsed" desc="hashCode">
2586 /**
2587 * Compute a hash code on a type.
2588 */
2589 public static int hashCode(Type t) {
2590 return hashCode.visit(t);
2591 }
2592 // where
2593 private static final UnaryVisitor<Integer> hashCode = new UnaryVisitor<Integer>() {
2595 public Integer visitType(Type t, Void ignored) {
2596 return t.tag;
2597 }
2599 @Override
2600 public Integer visitClassType(ClassType t, Void ignored) {
2601 int result = visit(t.getEnclosingType());
2602 result *= 127;
2603 result += t.tsym.flatName().hashCode();
2604 for (Type s : t.getTypeArguments()) {
2605 result *= 127;
2606 result += visit(s);
2607 }
2608 return result;
2609 }
2611 @Override
2612 public Integer visitWildcardType(WildcardType t, Void ignored) {
2613 int result = t.kind.hashCode();
2614 if (t.type != null) {
2615 result *= 127;
2616 result += visit(t.type);
2617 }
2618 return result;
2619 }
2621 @Override
2622 public Integer visitArrayType(ArrayType t, Void ignored) {
2623 return visit(t.elemtype) + 12;
2624 }
2626 @Override
2627 public Integer visitTypeVar(TypeVar t, Void ignored) {
2628 return System.identityHashCode(t.tsym);
2629 }
2631 @Override
2632 public Integer visitUndetVar(UndetVar t, Void ignored) {
2633 return System.identityHashCode(t);
2634 }
2636 @Override
2637 public Integer visitErrorType(ErrorType t, Void ignored) {
2638 return 0;
2639 }
2640 };
2641 // </editor-fold>
2643 // <editor-fold defaultstate="collapsed" desc="Return-Type-Substitutable">
2644 /**
2645 * Does t have a result that is a subtype of the result type of s,
2646 * suitable for covariant returns? It is assumed that both types
2647 * are (possibly polymorphic) method types. Monomorphic method
2648 * types are handled in the obvious way. Polymorphic method types
2649 * require renaming all type variables of one to corresponding
2650 * type variables in the other, where correspondence is by
2651 * position in the type parameter list. */
2652 public boolean resultSubtype(Type t, Type s, Warner warner) {
2653 List<Type> tvars = t.getTypeArguments();
2654 List<Type> svars = s.getTypeArguments();
2655 Type tres = t.getReturnType();
2656 Type sres = subst(s.getReturnType(), svars, tvars);
2657 return covariantReturnType(tres, sres, warner);
2658 }
2660 /**
2661 * Return-Type-Substitutable.
2662 * @see <a href="http://java.sun.com/docs/books/jls/">The Java
2663 * Language Specification, Third Ed. (8.4.5)</a>
2664 */
2665 public boolean returnTypeSubstitutable(Type r1, Type r2) {
2666 if (hasSameArgs(r1, r2))
2667 return resultSubtype(r1, r2, Warner.noWarnings);
2668 else
2669 return covariantReturnType(r1.getReturnType(),
2670 erasure(r2.getReturnType()),
2671 Warner.noWarnings);
2672 }
2674 public boolean returnTypeSubstitutable(Type r1,
2675 Type r2, Type r2res,
2676 Warner warner) {
2677 if (isSameType(r1.getReturnType(), r2res))
2678 return true;
2679 if (r1.getReturnType().isPrimitive() || r2res.isPrimitive())
2680 return false;
2682 if (hasSameArgs(r1, r2))
2683 return covariantReturnType(r1.getReturnType(), r2res, warner);
2684 if (!source.allowCovariantReturns())
2685 return false;
2686 if (isSubtypeUnchecked(r1.getReturnType(), r2res, warner))
2687 return true;
2688 if (!isSubtype(r1.getReturnType(), erasure(r2res)))
2689 return false;
2690 warner.warnUnchecked();
2691 return true;
2692 }
2694 /**
2695 * Is t an appropriate return type in an overrider for a
2696 * method that returns s?
2697 */
2698 public boolean covariantReturnType(Type t, Type s, Warner warner) {
2699 return
2700 isSameType(t, s) ||
2701 source.allowCovariantReturns() &&
2702 !t.isPrimitive() &&
2703 !s.isPrimitive() &&
2704 isAssignable(t, s, warner);
2705 }
2706 // </editor-fold>
2708 // <editor-fold defaultstate="collapsed" desc="Box/unbox support">
2709 /**
2710 * Return the class that boxes the given primitive.
2711 */
2712 public ClassSymbol boxedClass(Type t) {
2713 return reader.enterClass(syms.boxedName[t.tag]);
2714 }
2716 /**
2717 * Return the primitive type corresponding to a boxed type.
2718 */
2719 public Type unboxedType(Type t) {
2720 if (allowBoxing) {
2721 for (int i=0; i<syms.boxedName.length; i++) {
2722 Name box = syms.boxedName[i];
2723 if (box != null &&
2724 asSuper(t, reader.enterClass(box)) != null)
2725 return syms.typeOfTag[i];
2726 }
2727 }
2728 return Type.noType;
2729 }
2730 // </editor-fold>
2732 // <editor-fold defaultstate="collapsed" desc="Capture conversion">
2733 /*
2734 * JLS 3rd Ed. 5.1.10 Capture Conversion:
2735 *
2736 * Let G name a generic type declaration with n formal type
2737 * parameters A1 ... An with corresponding bounds U1 ... Un. There
2738 * exists a capture conversion from G<T1 ... Tn> to G<S1 ... Sn>,
2739 * where, for 1 <= i <= n:
2740 *
2741 * + If Ti is a wildcard type argument (4.5.1) of the form ? then
2742 * Si is a fresh type variable whose upper bound is
2743 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is the null
2744 * type.
2745 *
2746 * + If Ti is a wildcard type argument of the form ? extends Bi,
2747 * then Si is a fresh type variable whose upper bound is
2748 * glb(Bi, Ui[A1 := S1, ..., An := Sn]) and whose lower bound is
2749 * the null type, where glb(V1,... ,Vm) is V1 & ... & Vm. It is
2750 * a compile-time error if for any two classes (not interfaces)
2751 * Vi and Vj,Vi is not a subclass of Vj or vice versa.
2752 *
2753 * + If Ti is a wildcard type argument of the form ? super Bi,
2754 * then Si is a fresh type variable whose upper bound is
2755 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is Bi.
2756 *
2757 * + Otherwise, Si = Ti.
2758 *
2759 * Capture conversion on any type other than a parameterized type
2760 * (4.5) acts as an identity conversion (5.1.1). Capture
2761 * conversions never require a special action at run time and
2762 * therefore never throw an exception at run time.
2763 *
2764 * Capture conversion is not applied recursively.
2765 */
2766 /**
2767 * Capture conversion as specified by JLS 3rd Ed.
2768 */
2769 public Type capture(Type t) {
2770 if (t.tag != CLASS)
2771 return t;
2772 ClassType cls = (ClassType)t;
2773 if (cls.isRaw() || !cls.isParameterized())
2774 return cls;
2776 ClassType G = (ClassType)cls.asElement().asType();
2777 List<Type> A = G.getTypeArguments();
2778 List<Type> T = cls.getTypeArguments();
2779 List<Type> S = freshTypeVariables(T);
2781 List<Type> currentA = A;
2782 List<Type> currentT = T;
2783 List<Type> currentS = S;
2784 boolean captured = false;
2785 while (!currentA.isEmpty() &&
2786 !currentT.isEmpty() &&
2787 !currentS.isEmpty()) {
2788 if (currentS.head != currentT.head) {
2789 captured = true;
2790 WildcardType Ti = (WildcardType)currentT.head;
2791 Type Ui = currentA.head.getUpperBound();
2792 CapturedType Si = (CapturedType)currentS.head;
2793 if (Ui == null)
2794 Ui = syms.objectType;
2795 switch (Ti.kind) {
2796 case UNBOUND:
2797 Si.bound = subst(Ui, A, S);
2798 Si.lower = syms.botType;
2799 break;
2800 case EXTENDS:
2801 Si.bound = glb(Ti.getExtendsBound(), subst(Ui, A, S));
2802 Si.lower = syms.botType;
2803 break;
2804 case SUPER:
2805 Si.bound = subst(Ui, A, S);
2806 Si.lower = Ti.getSuperBound();
2807 break;
2808 }
2809 if (Si.bound == Si.lower)
2810 currentS.head = Si.bound;
2811 }
2812 currentA = currentA.tail;
2813 currentT = currentT.tail;
2814 currentS = currentS.tail;
2815 }
2816 if (!currentA.isEmpty() || !currentT.isEmpty() || !currentS.isEmpty())
2817 return erasure(t); // some "rare" type involved
2819 if (captured)
2820 return new ClassType(cls.getEnclosingType(), S, cls.tsym);
2821 else
2822 return t;
2823 }
2824 // where
2825 private List<Type> freshTypeVariables(List<Type> types) {
2826 ListBuffer<Type> result = lb();
2827 for (Type t : types) {
2828 if (t.tag == WILDCARD) {
2829 Type bound = ((WildcardType)t).getExtendsBound();
2830 if (bound == null)
2831 bound = syms.objectType;
2832 result.append(new CapturedType(capturedName,
2833 syms.noSymbol,
2834 bound,
2835 syms.botType,
2836 (WildcardType)t));
2837 } else {
2838 result.append(t);
2839 }
2840 }
2841 return result.toList();
2842 }
2843 // </editor-fold>
2845 // <editor-fold defaultstate="collapsed" desc="Internal utility methods">
2846 private List<Type> upperBounds(List<Type> ss) {
2847 if (ss.isEmpty()) return ss;
2848 Type head = upperBound(ss.head);
2849 List<Type> tail = upperBounds(ss.tail);
2850 if (head != ss.head || tail != ss.tail)
2851 return tail.prepend(head);
2852 else
2853 return ss;
2854 }
2856 private boolean sideCast(Type from, Type to, Warner warn) {
2857 // We are casting from type $from$ to type $to$, which are
2858 // non-final unrelated types. This method
2859 // tries to reject a cast by transferring type parameters
2860 // from $to$ to $from$ by common superinterfaces.
2861 boolean reverse = false;
2862 Type target = to;
2863 if ((to.tsym.flags() & INTERFACE) == 0) {
2864 assert (from.tsym.flags() & INTERFACE) != 0;
2865 reverse = true;
2866 to = from;
2867 from = target;
2868 }
2869 List<Type> commonSupers = superClosure(to, erasure(from));
2870 boolean giveWarning = commonSupers.isEmpty();
2871 // The arguments to the supers could be unified here to
2872 // get a more accurate analysis
2873 while (commonSupers.nonEmpty()) {
2874 Type t1 = asSuper(from, commonSupers.head.tsym);
2875 Type t2 = commonSupers.head; // same as asSuper(to, commonSupers.head.tsym);
2876 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
2877 return false;
2878 giveWarning = giveWarning || (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2));
2879 commonSupers = commonSupers.tail;
2880 }
2881 if (giveWarning && !isReifiable(to))
2882 warn.warnUnchecked();
2883 if (!source.allowCovariantReturns())
2884 // reject if there is a common method signature with
2885 // incompatible return types.
2886 chk.checkCompatibleAbstracts(warn.pos(), from, to);
2887 return true;
2888 }
2890 private boolean sideCastFinal(Type from, Type to, Warner warn) {
2891 // We are casting from type $from$ to type $to$, which are
2892 // unrelated types one of which is final and the other of
2893 // which is an interface. This method
2894 // tries to reject a cast by transferring type parameters
2895 // from the final class to the interface.
2896 boolean reverse = false;
2897 Type target = to;
2898 if ((to.tsym.flags() & INTERFACE) == 0) {
2899 assert (from.tsym.flags() & INTERFACE) != 0;
2900 reverse = true;
2901 to = from;
2902 from = target;
2903 }
2904 assert (from.tsym.flags() & FINAL) != 0;
2905 Type t1 = asSuper(from, to.tsym);
2906 if (t1 == null) return false;
2907 Type t2 = to;
2908 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
2909 return false;
2910 if (!source.allowCovariantReturns())
2911 // reject if there is a common method signature with
2912 // incompatible return types.
2913 chk.checkCompatibleAbstracts(warn.pos(), from, to);
2914 if (!isReifiable(target) &&
2915 (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2)))
2916 warn.warnUnchecked();
2917 return true;
2918 }
2920 private boolean giveWarning(Type from, Type to) {
2921 // To and from are (possibly different) parameterizations
2922 // of the same class or interface
2923 return to.isParameterized() && !containsType(to.getTypeArguments(), from.getTypeArguments());
2924 }
2926 private List<Type> superClosure(Type t, Type s) {
2927 List<Type> cl = List.nil();
2928 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
2929 if (isSubtype(s, erasure(l.head))) {
2930 cl = insert(cl, l.head);
2931 } else {
2932 cl = union(cl, superClosure(l.head, s));
2933 }
2934 }
2935 return cl;
2936 }
2938 private boolean containsTypeEquivalent(Type t, Type s) {
2939 return
2940 isSameType(t, s) || // shortcut
2941 containsType(t, s) && containsType(s, t);
2942 }
2944 /**
2945 * Adapt a type by computing a substitution which maps a source
2946 * type to a target type.
2947 *
2948 * @param source the source type
2949 * @param target the target type
2950 * @param from the type variables of the computed substitution
2951 * @param to the types of the computed substitution.
2952 */
2953 public void adapt(Type source,
2954 Type target,
2955 ListBuffer<Type> from,
2956 ListBuffer<Type> to) throws AdaptFailure {
2957 Map<Symbol,Type> mapping = new HashMap<Symbol,Type>();
2958 adaptRecursive(source, target, from, to, mapping);
2959 List<Type> fromList = from.toList();
2960 List<Type> toList = to.toList();
2961 while (!fromList.isEmpty()) {
2962 Type val = mapping.get(fromList.head.tsym);
2963 if (toList.head != val)
2964 toList.head = val;
2965 fromList = fromList.tail;
2966 toList = toList.tail;
2967 }
2968 }
2969 // where
2970 private void adaptRecursive(Type source,
2971 Type target,
2972 ListBuffer<Type> from,
2973 ListBuffer<Type> to,
2974 Map<Symbol,Type> mapping) throws AdaptFailure {
2975 if (source.tag == TYPEVAR) {
2976 // Check to see if there is
2977 // already a mapping for $source$, in which case
2978 // the old mapping will be merged with the new
2979 Type val = mapping.get(source.tsym);
2980 if (val != null) {
2981 if (val.isSuperBound() && target.isSuperBound()) {
2982 val = isSubtype(lowerBound(val), lowerBound(target))
2983 ? target : val;
2984 } else if (val.isExtendsBound() && target.isExtendsBound()) {
2985 val = isSubtype(upperBound(val), upperBound(target))
2986 ? val : target;
2987 } else if (!isSameType(val, target)) {
2988 throw new AdaptFailure();
2989 }
2990 } else {
2991 val = target;
2992 from.append(source);
2993 to.append(target);
2994 }
2995 mapping.put(source.tsym, val);
2996 } else if (source.tag == target.tag) {
2997 switch (source.tag) {
2998 case CLASS:
2999 adapt(source.allparams(), target.allparams(),
3000 from, to, mapping);
3001 break;
3002 case ARRAY:
3003 adaptRecursive(elemtype(source), elemtype(target),
3004 from, to, mapping);
3005 break;
3006 case WILDCARD:
3007 if (source.isExtendsBound()) {
3008 adaptRecursive(upperBound(source), upperBound(target),
3009 from, to, mapping);
3010 } else if (source.isSuperBound()) {
3011 adaptRecursive(lowerBound(source), lowerBound(target),
3012 from, to, mapping);
3013 }
3014 break;
3015 }
3016 }
3017 }
3018 public static class AdaptFailure extends Exception {
3019 static final long serialVersionUID = -7490231548272701566L;
3020 }
3022 /**
3023 * Adapt a type by computing a substitution which maps a list of
3024 * source types to a list of target types.
3025 *
3026 * @param source the source type
3027 * @param target the target type
3028 * @param from the type variables of the computed substitution
3029 * @param to the types of the computed substitution.
3030 */
3031 private void adapt(List<Type> source,
3032 List<Type> target,
3033 ListBuffer<Type> from,
3034 ListBuffer<Type> to,
3035 Map<Symbol,Type> mapping) throws AdaptFailure {
3036 if (source.length() == target.length()) {
3037 while (source.nonEmpty()) {
3038 adaptRecursive(source.head, target.head, from, to, mapping);
3039 source = source.tail;
3040 target = target.tail;
3041 }
3042 }
3043 }
3045 private void adaptSelf(Type t,
3046 ListBuffer<Type> from,
3047 ListBuffer<Type> to) {
3048 try {
3049 //if (t.tsym.type != t)
3050 adapt(t.tsym.type, t, from, to);
3051 } catch (AdaptFailure ex) {
3052 // Adapt should never fail calculating a mapping from
3053 // t.tsym.type to t as there can be no merge problem.
3054 throw new AssertionError(ex);
3055 }
3056 }
3058 /**
3059 * Rewrite all type variables (universal quantifiers) in the given
3060 * type to wildcards (existential quantifiers). This is used to
3061 * determine if a cast is allowed. For example, if high is true
3062 * and {@code T <: Number}, then {@code List<T>} is rewritten to
3063 * {@code List<? extends Number>}. Since {@code List<Integer> <:
3064 * List<? extends Number>} a {@code List<T>} can be cast to {@code
3065 * List<Integer>} with a warning.
3066 * @param t a type
3067 * @param high if true return an upper bound; otherwise a lower
3068 * bound
3069 * @param rewriteTypeVars only rewrite captured wildcards if false;
3070 * otherwise rewrite all type variables
3071 * @return the type rewritten with wildcards (existential
3072 * quantifiers) only
3073 */
3074 private Type rewriteQuantifiers(Type t, boolean high, boolean rewriteTypeVars) {
3075 ListBuffer<Type> from = new ListBuffer<Type>();
3076 ListBuffer<Type> to = new ListBuffer<Type>();
3077 adaptSelf(t, from, to);
3078 ListBuffer<Type> rewritten = new ListBuffer<Type>();
3079 List<Type> formals = from.toList();
3080 boolean changed = false;
3081 for (Type arg : to.toList()) {
3082 Type bound;
3083 if (rewriteTypeVars && arg.tag == TYPEVAR) {
3084 TypeVar tv = (TypeVar)arg;
3085 bound = high ? tv.bound : syms.botType;
3086 } else {
3087 bound = high ? upperBound(arg) : lowerBound(arg);
3088 }
3089 Type newarg = bound;
3090 if (arg != bound) {
3091 changed = true;
3092 newarg = high ? makeExtendsWildcard(bound, (TypeVar)formals.head)
3093 : makeSuperWildcard(bound, (TypeVar)formals.head);
3094 }
3095 rewritten.append(newarg);
3096 formals = formals.tail;
3097 }
3098 if (changed)
3099 return subst(t.tsym.type, from.toList(), rewritten.toList());
3100 else
3101 return t;
3102 }
3104 /**
3105 * Create a wildcard with the given upper (extends) bound; create
3106 * an unbounded wildcard if bound is Object.
3107 *
3108 * @param bound the upper bound
3109 * @param formal the formal type parameter that will be
3110 * substituted by the wildcard
3111 */
3112 private WildcardType makeExtendsWildcard(Type bound, TypeVar formal) {
3113 if (bound == syms.objectType) {
3114 return new WildcardType(syms.objectType,
3115 BoundKind.UNBOUND,
3116 syms.boundClass,
3117 formal);
3118 } else {
3119 return new WildcardType(bound,
3120 BoundKind.EXTENDS,
3121 syms.boundClass,
3122 formal);
3123 }
3124 }
3126 /**
3127 * Create a wildcard with the given lower (super) bound; create an
3128 * unbounded wildcard if bound is bottom (type of {@code null}).
3129 *
3130 * @param bound the lower bound
3131 * @param formal the formal type parameter that will be
3132 * substituted by the wildcard
3133 */
3134 private WildcardType makeSuperWildcard(Type bound, TypeVar formal) {
3135 if (bound.tag == BOT) {
3136 return new WildcardType(syms.objectType,
3137 BoundKind.UNBOUND,
3138 syms.boundClass,
3139 formal);
3140 } else {
3141 return new WildcardType(bound,
3142 BoundKind.SUPER,
3143 syms.boundClass,
3144 formal);
3145 }
3146 }
3148 /**
3149 * A wrapper for a type that allows use in sets.
3150 */
3151 class SingletonType {
3152 final Type t;
3153 SingletonType(Type t) {
3154 this.t = t;
3155 }
3156 public int hashCode() {
3157 return Types.this.hashCode(t);
3158 }
3159 public boolean equals(Object obj) {
3160 return (obj instanceof SingletonType) &&
3161 isSameType(t, ((SingletonType)obj).t);
3162 }
3163 public String toString() {
3164 return t.toString();
3165 }
3166 }
3167 // </editor-fold>
3169 // <editor-fold defaultstate="collapsed" desc="Visitors">
3170 /**
3171 * A default visitor for types. All visitor methods except
3172 * visitType are implemented by delegating to visitType. Concrete
3173 * subclasses must provide an implementation of visitType and can
3174 * override other methods as needed.
3175 *
3176 * @param <R> the return type of the operation implemented by this
3177 * visitor; use Void if no return type is needed.
3178 * @param <S> the type of the second argument (the first being the
3179 * type itself) of the operation implemented by this visitor; use
3180 * Void if a second argument is not needed.
3181 */
3182 public static abstract class DefaultTypeVisitor<R,S> implements Type.Visitor<R,S> {
3183 final public R visit(Type t, S s) { return t.accept(this, s); }
3184 public R visitClassType(ClassType t, S s) { return visitType(t, s); }
3185 public R visitWildcardType(WildcardType t, S s) { return visitType(t, s); }
3186 public R visitArrayType(ArrayType t, S s) { return visitType(t, s); }
3187 public R visitMethodType(MethodType t, S s) { return visitType(t, s); }
3188 public R visitPackageType(PackageType t, S s) { return visitType(t, s); }
3189 public R visitTypeVar(TypeVar t, S s) { return visitType(t, s); }
3190 public R visitCapturedType(CapturedType t, S s) { return visitType(t, s); }
3191 public R visitForAll(ForAll t, S s) { return visitType(t, s); }
3192 public R visitUndetVar(UndetVar t, S s) { return visitType(t, s); }
3193 public R visitErrorType(ErrorType t, S s) { return visitType(t, s); }
3194 }
3196 /**
3197 * A <em>simple</em> visitor for types. This visitor is simple as
3198 * captured wildcards, for-all types (generic methods), and
3199 * undetermined type variables (part of inference) are hidden.
3200 * Captured wildcards are hidden by treating them as type
3201 * variables and the rest are hidden by visiting their qtypes.
3202 *
3203 * @param <R> the return type of the operation implemented by this
3204 * visitor; use Void if no return type is needed.
3205 * @param <S> the type of the second argument (the first being the
3206 * type itself) of the operation implemented by this visitor; use
3207 * Void if a second argument is not needed.
3208 */
3209 public static abstract class SimpleVisitor<R,S> extends DefaultTypeVisitor<R,S> {
3210 @Override
3211 public R visitCapturedType(CapturedType t, S s) {
3212 return visitTypeVar(t, s);
3213 }
3214 @Override
3215 public R visitForAll(ForAll t, S s) {
3216 return visit(t.qtype, s);
3217 }
3218 @Override
3219 public R visitUndetVar(UndetVar t, S s) {
3220 return visit(t.qtype, s);
3221 }
3222 }
3224 /**
3225 * A plain relation on types. That is a 2-ary function on the
3226 * form Type × Type → Boolean.
3227 * <!-- In plain text: Type x Type -> Boolean -->
3228 */
3229 public static abstract class TypeRelation extends SimpleVisitor<Boolean,Type> {}
3231 /**
3232 * A convenience visitor for implementing operations that only
3233 * require one argument (the type itself), that is, unary
3234 * operations.
3235 *
3236 * @param <R> the return type of the operation implemented by this
3237 * visitor; use Void if no return type is needed.
3238 */
3239 public static abstract class UnaryVisitor<R> extends SimpleVisitor<R,Void> {
3240 final public R visit(Type t) { return t.accept(this, null); }
3241 }
3243 /**
3244 * A visitor for implementing a mapping from types to types. The
3245 * default behavior of this class is to implement the identity
3246 * mapping (mapping a type to itself). This can be overridden in
3247 * subclasses.
3248 *
3249 * @param <S> the type of the second argument (the first being the
3250 * type itself) of this mapping; use Void if a second argument is
3251 * not needed.
3252 */
3253 public static class MapVisitor<S> extends DefaultTypeVisitor<Type,S> {
3254 final public Type visit(Type t) { return t.accept(this, null); }
3255 public Type visitType(Type t, S s) { return t; }
3256 }
3257 // </editor-fold>
3258 }
