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src/share/classes/com/sun/tools/javac/code/Types.java@03944ee4fac4
src/share/classes/com/sun/tools/javac/code/Types.java
Fri, 26 Jun 2009 18:51:39 -0700
- author
- jjg
- date
- Fri, 26 Jun 2009 18:51:39 -0700
- changeset 308
- 03944ee4fac4
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- 22872b24d38c
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6843077: JSR 308: Annotations on types
Reviewed-by: jjg, mcimadamore, darcy
Contributed-by: mernst@cs.washington.edu, mali@csail.mit.edu, mpapi@csail.mit.edu
1 /*
2 * Copyright 2003-2009 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.api.Messages;
32 import com.sun.tools.javac.util.*;
33 import com.sun.tools.javac.util.List;
35 import com.sun.tools.javac.jvm.ClassReader;
36 import com.sun.tools.javac.comp.Check;
38 import static com.sun.tools.javac.code.Type.*;
39 import static com.sun.tools.javac.code.TypeTags.*;
40 import static com.sun.tools.javac.code.Symbol.*;
41 import static com.sun.tools.javac.code.Flags.*;
42 import static com.sun.tools.javac.code.BoundKind.*;
43 import static com.sun.tools.javac.util.ListBuffer.lb;
45 /**
46 * Utility class containing various operations on types.
47 *
48 * <p>Unless other names are more illustrative, the following naming
49 * conventions should be observed in this file:
50 *
51 * <dl>
52 * <dt>t</dt>
53 * <dd>If the first argument to an operation is a type, it should be named t.</dd>
54 * <dt>s</dt>
55 * <dd>Similarly, if the second argument to an operation is a type, it should be named s.</dd>
56 * <dt>ts</dt>
57 * <dd>If an operations takes a list of types, the first should be named ts.</dd>
58 * <dt>ss</dt>
59 * <dd>A second list of types should be named ss.</dd>
60 * </dl>
61 *
62 * <p><b>This is NOT part of any API supported by Sun Microsystems.
63 * If you write code that depends on this, you do so at your own risk.
64 * This code and its internal interfaces are subject to change or
65 * deletion without notice.</b>
66 */
67 public class Types {
68 protected static final Context.Key<Types> typesKey =
69 new Context.Key<Types>();
71 final Symtab syms;
72 final JavacMessages messages;
73 final Names names;
74 final boolean allowBoxing;
75 final ClassReader reader;
76 final Source source;
77 final Check chk;
78 List<Warner> warnStack = List.nil();
79 final Name capturedName;
81 // <editor-fold defaultstate="collapsed" desc="Instantiating">
82 public static Types instance(Context context) {
83 Types instance = context.get(typesKey);
84 if (instance == null)
85 instance = new Types(context);
86 return instance;
87 }
89 protected Types(Context context) {
90 context.put(typesKey, this);
91 syms = Symtab.instance(context);
92 names = Names.instance(context);
93 allowBoxing = Source.instance(context).allowBoxing();
94 reader = ClassReader.instance(context);
95 source = Source.instance(context);
96 chk = Check.instance(context);
97 capturedName = names.fromString("<captured wildcard>");
98 messages = JavacMessages.instance(context);
99 }
100 // </editor-fold>
102 // <editor-fold defaultstate="collapsed" desc="upperBound">
103 /**
104 * The "rvalue conversion".<br>
105 * The upper bound of most types is the type
106 * itself. Wildcards, on the other hand have upper
107 * and lower bounds.
108 * @param t a type
109 * @return the upper bound of the given type
110 */
111 public Type upperBound(Type t) {
112 return upperBound.visit(t);
113 }
114 // where
115 private final MapVisitor<Void> upperBound = new MapVisitor<Void>() {
117 @Override
118 public Type visitWildcardType(WildcardType t, Void ignored) {
119 if (t.isSuperBound())
120 return t.bound == null ? syms.objectType : t.bound.bound;
121 else
122 return visit(t.type);
123 }
125 @Override
126 public Type visitCapturedType(CapturedType t, Void ignored) {
127 return visit(t.bound);
128 }
129 };
130 // </editor-fold>
132 // <editor-fold defaultstate="collapsed" desc="lowerBound">
133 /**
134 * The "lvalue conversion".<br>
135 * The lower bound of most types is the type
136 * itself. Wildcards, on the other hand have upper
137 * and lower bounds.
138 * @param t a type
139 * @return the lower bound of the given type
140 */
141 public Type lowerBound(Type t) {
142 return lowerBound.visit(t);
143 }
144 // where
145 private final MapVisitor<Void> lowerBound = new MapVisitor<Void>() {
147 @Override
148 public Type visitWildcardType(WildcardType t, Void ignored) {
149 return t.isExtendsBound() ? syms.botType : visit(t.type);
150 }
152 @Override
153 public Type visitCapturedType(CapturedType t, Void ignored) {
154 return visit(t.getLowerBound());
155 }
156 };
157 // </editor-fold>
159 // <editor-fold defaultstate="collapsed" desc="isUnbounded">
160 /**
161 * Checks that all the arguments to a class are unbounded
162 * wildcards or something else that doesn't make any restrictions
163 * on the arguments. If a class isUnbounded, a raw super- or
164 * subclass can be cast to it without a warning.
165 * @param t a type
166 * @return true iff the given type is unbounded or raw
167 */
168 public boolean isUnbounded(Type t) {
169 return isUnbounded.visit(t);
170 }
171 // where
172 private final UnaryVisitor<Boolean> isUnbounded = new UnaryVisitor<Boolean>() {
174 public Boolean visitType(Type t, Void ignored) {
175 return true;
176 }
178 @Override
179 public Boolean visitClassType(ClassType t, Void ignored) {
180 List<Type> parms = t.tsym.type.allparams();
181 List<Type> args = t.allparams();
182 while (parms.nonEmpty()) {
183 WildcardType unb = new WildcardType(syms.objectType,
184 BoundKind.UNBOUND,
185 syms.boundClass,
186 (TypeVar)parms.head);
187 if (!containsType(args.head, unb))
188 return false;
189 parms = parms.tail;
190 args = args.tail;
191 }
192 return true;
193 }
194 };
195 // </editor-fold>
197 // <editor-fold defaultstate="collapsed" desc="asSub">
198 /**
199 * Return the least specific subtype of t that starts with symbol
200 * sym. If none exists, return null. The least specific subtype
201 * is determined as follows:
202 *
203 * <p>If there is exactly one parameterized instance of sym that is a
204 * subtype of t, that parameterized instance is returned.<br>
205 * Otherwise, if the plain type or raw type `sym' is a subtype of
206 * type t, the type `sym' itself is returned. Otherwise, null is
207 * returned.
208 */
209 public Type asSub(Type t, Symbol sym) {
210 return asSub.visit(t, sym);
211 }
212 // where
213 private final SimpleVisitor<Type,Symbol> asSub = new SimpleVisitor<Type,Symbol>() {
215 public Type visitType(Type t, Symbol sym) {
216 return null;
217 }
219 @Override
220 public Type visitClassType(ClassType t, Symbol sym) {
221 if (t.tsym == sym)
222 return t;
223 Type base = asSuper(sym.type, t.tsym);
224 if (base == null)
225 return null;
226 ListBuffer<Type> from = new ListBuffer<Type>();
227 ListBuffer<Type> to = new ListBuffer<Type>();
228 try {
229 adapt(base, t, from, to);
230 } catch (AdaptFailure ex) {
231 return null;
232 }
233 Type res = subst(sym.type, from.toList(), to.toList());
234 if (!isSubtype(res, t))
235 return null;
236 ListBuffer<Type> openVars = new ListBuffer<Type>();
237 for (List<Type> l = sym.type.allparams();
238 l.nonEmpty(); l = l.tail)
239 if (res.contains(l.head) && !t.contains(l.head))
240 openVars.append(l.head);
241 if (openVars.nonEmpty()) {
242 if (t.isRaw()) {
243 // The subtype of a raw type is raw
244 res = erasure(res);
245 } else {
246 // Unbound type arguments default to ?
247 List<Type> opens = openVars.toList();
248 ListBuffer<Type> qs = new ListBuffer<Type>();
249 for (List<Type> iter = opens; iter.nonEmpty(); iter = iter.tail) {
250 qs.append(new WildcardType(syms.objectType, BoundKind.UNBOUND, syms.boundClass, (TypeVar) iter.head));
251 }
252 res = subst(res, opens, qs.toList());
253 }
254 }
255 return res;
256 }
258 @Override
259 public Type visitErrorType(ErrorType t, Symbol sym) {
260 return t;
261 }
262 };
263 // </editor-fold>
265 // <editor-fold defaultstate="collapsed" desc="isConvertible">
266 /**
267 * Is t a subtype of or convertiable via boxing/unboxing
268 * convertions to s?
269 */
270 public boolean isConvertible(Type t, Type s, Warner warn) {
271 boolean tPrimitive = t.isPrimitive();
272 boolean sPrimitive = s.isPrimitive();
273 if (tPrimitive == sPrimitive)
274 return isSubtypeUnchecked(t, s, warn);
275 if (!allowBoxing) return false;
276 return tPrimitive
277 ? isSubtype(boxedClass(t).type, s)
278 : isSubtype(unboxedType(t), s);
279 }
281 /**
282 * Is t a subtype of or convertiable via boxing/unboxing
283 * convertions to s?
284 */
285 public boolean isConvertible(Type t, Type s) {
286 return isConvertible(t, s, Warner.noWarnings);
287 }
288 // </editor-fold>
290 // <editor-fold defaultstate="collapsed" desc="isSubtype">
291 /**
292 * Is t an unchecked subtype of s?
293 */
294 public boolean isSubtypeUnchecked(Type t, Type s) {
295 return isSubtypeUnchecked(t, s, Warner.noWarnings);
296 }
297 /**
298 * Is t an unchecked subtype of s?
299 */
300 public boolean isSubtypeUnchecked(Type t, Type s, Warner warn) {
301 if (t.tag == ARRAY && s.tag == ARRAY) {
302 return (((ArrayType)t).elemtype.tag <= lastBaseTag)
303 ? isSameType(elemtype(t), elemtype(s))
304 : isSubtypeUnchecked(elemtype(t), elemtype(s), warn);
305 } else if (isSubtype(t, s)) {
306 return true;
307 }
308 else if (t.tag == TYPEVAR) {
309 return isSubtypeUnchecked(t.getUpperBound(), s, warn);
310 }
311 else if (s.tag == UNDETVAR) {
312 UndetVar uv = (UndetVar)s;
313 if (uv.inst != null)
314 return isSubtypeUnchecked(t, uv.inst, warn);
315 }
316 else if (!s.isRaw()) {
317 Type t2 = asSuper(t, s.tsym);
318 if (t2 != null && t2.isRaw()) {
319 if (isReifiable(s))
320 warn.silentUnchecked();
321 else
322 warn.warnUnchecked();
323 return true;
324 }
325 }
326 return false;
327 }
329 /**
330 * Is t a subtype of s?<br>
331 * (not defined for Method and ForAll types)
332 */
333 final public boolean isSubtype(Type t, Type s) {
334 return isSubtype(t, s, true);
335 }
336 final public boolean isSubtypeNoCapture(Type t, Type s) {
337 return isSubtype(t, s, false);
338 }
339 public boolean isSubtype(Type t, Type s, boolean capture) {
340 if (t == s)
341 return true;
343 if (s.tag >= firstPartialTag)
344 return isSuperType(s, t);
346 if (s.isCompound()) {
347 for (Type s2 : interfaces(s).prepend(supertype(s))) {
348 if (!isSubtype(t, s2, capture))
349 return false;
350 }
351 return true;
352 }
354 Type lower = lowerBound(s);
355 if (s != lower)
356 return isSubtype(capture ? capture(t) : t, lower, false);
358 return isSubtype.visit(capture ? capture(t) : t, s);
359 }
360 // where
361 private TypeRelation isSubtype = new TypeRelation()
362 {
363 public Boolean visitType(Type t, Type s) {
364 switch (t.tag) {
365 case BYTE: case CHAR:
366 return (t.tag == s.tag ||
367 t.tag + 2 <= s.tag && s.tag <= DOUBLE);
368 case SHORT: case INT: case LONG: case FLOAT: case DOUBLE:
369 return t.tag <= s.tag && s.tag <= DOUBLE;
370 case BOOLEAN: case VOID:
371 return t.tag == s.tag;
372 case TYPEVAR:
373 return isSubtypeNoCapture(t.getUpperBound(), s);
374 case BOT:
375 return
376 s.tag == BOT || s.tag == CLASS ||
377 s.tag == ARRAY || s.tag == TYPEVAR;
378 case NONE:
379 return false;
380 default:
381 throw new AssertionError("isSubtype " + t.tag);
382 }
383 }
385 private Set<TypePair> cache = new HashSet<TypePair>();
387 private boolean containsTypeRecursive(Type t, Type s) {
388 TypePair pair = new TypePair(t, s);
389 if (cache.add(pair)) {
390 try {
391 return containsType(t.getTypeArguments(),
392 s.getTypeArguments());
393 } finally {
394 cache.remove(pair);
395 }
396 } else {
397 return containsType(t.getTypeArguments(),
398 rewriteSupers(s).getTypeArguments());
399 }
400 }
402 private Type rewriteSupers(Type t) {
403 if (!t.isParameterized())
404 return t;
405 ListBuffer<Type> from = lb();
406 ListBuffer<Type> to = lb();
407 adaptSelf(t, from, to);
408 if (from.isEmpty())
409 return t;
410 ListBuffer<Type> rewrite = lb();
411 boolean changed = false;
412 for (Type orig : to.toList()) {
413 Type s = rewriteSupers(orig);
414 if (s.isSuperBound() && !s.isExtendsBound()) {
415 s = new WildcardType(syms.objectType,
416 BoundKind.UNBOUND,
417 syms.boundClass);
418 changed = true;
419 } else if (s != orig) {
420 s = new WildcardType(upperBound(s),
421 BoundKind.EXTENDS,
422 syms.boundClass);
423 changed = true;
424 }
425 rewrite.append(s);
426 }
427 if (changed)
428 return subst(t.tsym.type, from.toList(), rewrite.toList());
429 else
430 return t;
431 }
433 @Override
434 public Boolean visitClassType(ClassType t, Type s) {
435 Type sup = asSuper(t, s.tsym);
436 return sup != null
437 && sup.tsym == s.tsym
438 // You're not allowed to write
439 // Vector<Object> vec = new Vector<String>();
440 // But with wildcards you can write
441 // Vector<? extends Object> vec = new Vector<String>();
442 // which means that subtype checking must be done
443 // here instead of same-type checking (via containsType).
444 && (!s.isParameterized() || containsTypeRecursive(s, sup))
445 && isSubtypeNoCapture(sup.getEnclosingType(),
446 s.getEnclosingType());
447 }
449 @Override
450 public Boolean visitArrayType(ArrayType t, Type s) {
451 if (s.tag == ARRAY) {
452 if (t.elemtype.tag <= lastBaseTag)
453 return isSameType(t.elemtype, elemtype(s));
454 else
455 return isSubtypeNoCapture(t.elemtype, elemtype(s));
456 }
458 if (s.tag == CLASS) {
459 Name sname = s.tsym.getQualifiedName();
460 return sname == names.java_lang_Object
461 || sname == names.java_lang_Cloneable
462 || sname == names.java_io_Serializable;
463 }
465 return false;
466 }
468 @Override
469 public Boolean visitUndetVar(UndetVar t, Type s) {
470 //todo: test against origin needed? or replace with substitution?
471 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
472 return true;
474 if (t.inst != null)
475 return isSubtypeNoCapture(t.inst, s); // TODO: ", warn"?
477 t.hibounds = t.hibounds.prepend(s);
478 return true;
479 }
481 @Override
482 public Boolean visitErrorType(ErrorType t, Type s) {
483 return true;
484 }
485 };
487 /**
488 * Is t a subtype of every type in given list `ts'?<br>
489 * (not defined for Method and ForAll types)<br>
490 * Allows unchecked conversions.
491 */
492 public boolean isSubtypeUnchecked(Type t, List<Type> ts, Warner warn) {
493 for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
494 if (!isSubtypeUnchecked(t, l.head, warn))
495 return false;
496 return true;
497 }
499 /**
500 * Are corresponding elements of ts subtypes of ss? If lists are
501 * of different length, return false.
502 */
503 public boolean isSubtypes(List<Type> ts, List<Type> ss) {
504 while (ts.tail != null && ss.tail != null
505 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
506 isSubtype(ts.head, ss.head)) {
507 ts = ts.tail;
508 ss = ss.tail;
509 }
510 return ts.tail == null && ss.tail == null;
511 /*inlined: ts.isEmpty() && ss.isEmpty();*/
512 }
514 /**
515 * Are corresponding elements of ts subtypes of ss, allowing
516 * unchecked conversions? If lists are of different length,
517 * return false.
518 **/
519 public boolean isSubtypesUnchecked(List<Type> ts, List<Type> ss, Warner warn) {
520 while (ts.tail != null && ss.tail != null
521 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
522 isSubtypeUnchecked(ts.head, ss.head, warn)) {
523 ts = ts.tail;
524 ss = ss.tail;
525 }
526 return ts.tail == null && ss.tail == null;
527 /*inlined: ts.isEmpty() && ss.isEmpty();*/
528 }
529 // </editor-fold>
531 // <editor-fold defaultstate="collapsed" desc="isSuperType">
532 /**
533 * Is t a supertype of s?
534 */
535 public boolean isSuperType(Type t, Type s) {
536 switch (t.tag) {
537 case ERROR:
538 return true;
539 case UNDETVAR: {
540 UndetVar undet = (UndetVar)t;
541 if (t == s ||
542 undet.qtype == s ||
543 s.tag == ERROR ||
544 s.tag == BOT) return true;
545 if (undet.inst != null)
546 return isSubtype(s, undet.inst);
547 undet.lobounds = undet.lobounds.prepend(s);
548 return true;
549 }
550 default:
551 return isSubtype(s, t);
552 }
553 }
554 // </editor-fold>
556 // <editor-fold defaultstate="collapsed" desc="isSameType">
557 /**
558 * Are corresponding elements of the lists the same type? If
559 * lists are of different length, return false.
560 */
561 public boolean isSameTypes(List<Type> ts, List<Type> ss) {
562 while (ts.tail != null && ss.tail != null
563 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
564 isSameType(ts.head, ss.head)) {
565 ts = ts.tail;
566 ss = ss.tail;
567 }
568 return ts.tail == null && ss.tail == null;
569 /*inlined: ts.isEmpty() && ss.isEmpty();*/
570 }
572 /**
573 * Is t the same type as s?
574 */
575 public boolean isSameType(Type t, Type s) {
576 return isSameType.visit(t, s);
577 }
578 // where
579 private TypeRelation isSameType = new TypeRelation() {
581 public Boolean visitType(Type t, Type s) {
582 if (t == s)
583 return true;
585 if (s.tag >= firstPartialTag)
586 return visit(s, t);
588 switch (t.tag) {
589 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
590 case DOUBLE: case BOOLEAN: case VOID: case BOT: case NONE:
591 return t.tag == s.tag;
592 case TYPEVAR:
593 return s.isSuperBound()
594 && !s.isExtendsBound()
595 && visit(t, upperBound(s));
596 default:
597 throw new AssertionError("isSameType " + t.tag);
598 }
599 }
601 @Override
602 public Boolean visitWildcardType(WildcardType t, Type s) {
603 if (s.tag >= firstPartialTag)
604 return visit(s, t);
605 else
606 return false;
607 }
609 @Override
610 public Boolean visitClassType(ClassType t, Type s) {
611 if (t == s)
612 return true;
614 if (s.tag >= firstPartialTag)
615 return visit(s, t);
617 if (s.isSuperBound() && !s.isExtendsBound())
618 return visit(t, upperBound(s)) && visit(t, lowerBound(s));
620 if (t.isCompound() && s.isCompound()) {
621 if (!visit(supertype(t), supertype(s)))
622 return false;
624 HashSet<SingletonType> set = new HashSet<SingletonType>();
625 for (Type x : interfaces(t))
626 set.add(new SingletonType(x));
627 for (Type x : interfaces(s)) {
628 if (!set.remove(new SingletonType(x)))
629 return false;
630 }
631 return (set.size() == 0);
632 }
633 return t.tsym == s.tsym
634 && visit(t.getEnclosingType(), s.getEnclosingType())
635 && containsTypeEquivalent(t.getTypeArguments(), s.getTypeArguments());
636 }
638 @Override
639 public Boolean visitArrayType(ArrayType t, Type s) {
640 if (t == s)
641 return true;
643 if (s.tag >= firstPartialTag)
644 return visit(s, t);
646 return s.tag == ARRAY
647 && containsTypeEquivalent(t.elemtype, elemtype(s));
648 }
650 @Override
651 public Boolean visitMethodType(MethodType t, Type s) {
652 // isSameType for methods does not take thrown
653 // exceptions into account!
654 return hasSameArgs(t, s) && visit(t.getReturnType(), s.getReturnType());
655 }
657 @Override
658 public Boolean visitPackageType(PackageType t, Type s) {
659 return t == s;
660 }
662 @Override
663 public Boolean visitForAll(ForAll t, Type s) {
664 if (s.tag != FORALL)
665 return false;
667 ForAll forAll = (ForAll)s;
668 return hasSameBounds(t, forAll)
669 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
670 }
672 @Override
673 public Boolean visitUndetVar(UndetVar t, Type s) {
674 if (s.tag == WILDCARD)
675 // FIXME, this might be leftovers from before capture conversion
676 return false;
678 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
679 return true;
681 if (t.inst != null)
682 return visit(t.inst, s);
684 t.inst = fromUnknownFun.apply(s);
685 for (List<Type> l = t.lobounds; l.nonEmpty(); l = l.tail) {
686 if (!isSubtype(l.head, t.inst))
687 return false;
688 }
689 for (List<Type> l = t.hibounds; l.nonEmpty(); l = l.tail) {
690 if (!isSubtype(t.inst, l.head))
691 return false;
692 }
693 return true;
694 }
696 @Override
697 public Boolean visitErrorType(ErrorType t, Type s) {
698 return true;
699 }
700 };
701 // </editor-fold>
703 // <editor-fold defaultstate="collapsed" desc="fromUnknownFun">
704 /**
705 * A mapping that turns all unknown types in this type to fresh
706 * unknown variables.
707 */
708 public Mapping fromUnknownFun = new Mapping("fromUnknownFun") {
709 public Type apply(Type t) {
710 if (t.tag == UNKNOWN) return new UndetVar(t);
711 else return t.map(this);
712 }
713 };
714 // </editor-fold>
716 // <editor-fold defaultstate="collapsed" desc="Contains Type">
717 public boolean containedBy(Type t, Type s) {
718 switch (t.tag) {
719 case UNDETVAR:
720 if (s.tag == WILDCARD) {
721 UndetVar undetvar = (UndetVar)t;
722 WildcardType wt = (WildcardType)s;
723 switch(wt.kind) {
724 case UNBOUND: //similar to ? extends Object
725 case EXTENDS: {
726 Type bound = upperBound(s);
727 // We should check the new upper bound against any of the
728 // undetvar's lower bounds.
729 for (Type t2 : undetvar.lobounds) {
730 if (!isSubtype(t2, bound))
731 return false;
732 }
733 undetvar.hibounds = undetvar.hibounds.prepend(bound);
734 break;
735 }
736 case SUPER: {
737 Type bound = lowerBound(s);
738 // We should check the new lower bound against any of the
739 // undetvar's lower bounds.
740 for (Type t2 : undetvar.hibounds) {
741 if (!isSubtype(bound, t2))
742 return false;
743 }
744 undetvar.lobounds = undetvar.lobounds.prepend(bound);
745 break;
746 }
747 }
748 return true;
749 } else {
750 return isSameType(t, s);
751 }
752 case ERROR:
753 return true;
754 default:
755 return containsType(s, t);
756 }
757 }
759 boolean containsType(List<Type> ts, List<Type> ss) {
760 while (ts.nonEmpty() && ss.nonEmpty()
761 && containsType(ts.head, ss.head)) {
762 ts = ts.tail;
763 ss = ss.tail;
764 }
765 return ts.isEmpty() && ss.isEmpty();
766 }
768 /**
769 * Check if t contains s.
770 *
771 * <p>T contains S if:
772 *
773 * <p>{@code L(T) <: L(S) && U(S) <: U(T)}
774 *
775 * <p>This relation is only used by ClassType.isSubtype(), that
776 * is,
777 *
778 * <p>{@code C<S> <: C<T> if T contains S.}
779 *
780 * <p>Because of F-bounds, this relation can lead to infinite
781 * recursion. Thus we must somehow break that recursion. Notice
782 * that containsType() is only called from ClassType.isSubtype().
783 * Since the arguments have already been checked against their
784 * bounds, we know:
785 *
786 * <p>{@code U(S) <: U(T) if T is "super" bound (U(T) *is* the bound)}
787 *
788 * <p>{@code L(T) <: L(S) if T is "extends" bound (L(T) is bottom)}
789 *
790 * @param t a type
791 * @param s a type
792 */
793 public boolean containsType(Type t, Type s) {
794 return containsType.visit(t, s);
795 }
796 // where
797 private TypeRelation containsType = new TypeRelation() {
799 private Type U(Type t) {
800 while (t.tag == WILDCARD) {
801 WildcardType w = (WildcardType)t;
802 if (w.isSuperBound())
803 return w.bound == null ? syms.objectType : w.bound.bound;
804 else
805 t = w.type;
806 }
807 return t;
808 }
810 private Type L(Type t) {
811 while (t.tag == WILDCARD) {
812 WildcardType w = (WildcardType)t;
813 if (w.isExtendsBound())
814 return syms.botType;
815 else
816 t = w.type;
817 }
818 return t;
819 }
821 public Boolean visitType(Type t, Type s) {
822 if (s.tag >= firstPartialTag)
823 return containedBy(s, t);
824 else
825 return isSameType(t, s);
826 }
828 void debugContainsType(WildcardType t, Type s) {
829 System.err.println();
830 System.err.format(" does %s contain %s?%n", t, s);
831 System.err.format(" %s U(%s) <: U(%s) %s = %s%n",
832 upperBound(s), s, t, U(t),
833 t.isSuperBound()
834 || isSubtypeNoCapture(upperBound(s), U(t)));
835 System.err.format(" %s L(%s) <: L(%s) %s = %s%n",
836 L(t), t, s, lowerBound(s),
837 t.isExtendsBound()
838 || isSubtypeNoCapture(L(t), lowerBound(s)));
839 System.err.println();
840 }
842 @Override
843 public Boolean visitWildcardType(WildcardType t, Type s) {
844 if (s.tag >= firstPartialTag)
845 return containedBy(s, t);
846 else {
847 // debugContainsType(t, s);
848 return isSameWildcard(t, s)
849 || isCaptureOf(s, t)
850 || ((t.isExtendsBound() || isSubtypeNoCapture(L(t), lowerBound(s))) &&
851 (t.isSuperBound() || isSubtypeNoCapture(upperBound(s), U(t))));
852 }
853 }
855 @Override
856 public Boolean visitUndetVar(UndetVar t, Type s) {
857 if (s.tag != WILDCARD)
858 return isSameType(t, s);
859 else
860 return false;
861 }
863 @Override
864 public Boolean visitErrorType(ErrorType t, Type s) {
865 return true;
866 }
867 };
869 public boolean isCaptureOf(Type s, WildcardType t) {
870 if (s.tag != TYPEVAR || !((TypeVar)s).isCaptured())
871 return false;
872 return isSameWildcard(t, ((CapturedType)s).wildcard);
873 }
875 public boolean isSameWildcard(WildcardType t, Type s) {
876 if (s.tag != WILDCARD)
877 return false;
878 WildcardType w = (WildcardType)s;
879 return w.kind == t.kind && w.type == t.type;
880 }
882 public boolean containsTypeEquivalent(List<Type> ts, List<Type> ss) {
883 while (ts.nonEmpty() && ss.nonEmpty()
884 && containsTypeEquivalent(ts.head, ss.head)) {
885 ts = ts.tail;
886 ss = ss.tail;
887 }
888 return ts.isEmpty() && ss.isEmpty();
889 }
890 // </editor-fold>
892 // <editor-fold defaultstate="collapsed" desc="isCastable">
893 public boolean isCastable(Type t, Type s) {
894 return isCastable(t, s, Warner.noWarnings);
895 }
897 /**
898 * Is t is castable to s?<br>
899 * s is assumed to be an erased type.<br>
900 * (not defined for Method and ForAll types).
901 */
902 public boolean isCastable(Type t, Type s, Warner warn) {
903 if (t == s)
904 return true;
906 if (t.isPrimitive() != s.isPrimitive())
907 return allowBoxing && isConvertible(t, s, warn);
909 if (warn != warnStack.head) {
910 try {
911 warnStack = warnStack.prepend(warn);
912 return isCastable.visit(t,s);
913 } finally {
914 warnStack = warnStack.tail;
915 }
916 } else {
917 return isCastable.visit(t,s);
918 }
919 }
920 // where
921 private TypeRelation isCastable = new TypeRelation() {
923 public Boolean visitType(Type t, Type s) {
924 if (s.tag == ERROR)
925 return true;
927 switch (t.tag) {
928 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
929 case DOUBLE:
930 return s.tag <= DOUBLE;
931 case BOOLEAN:
932 return s.tag == BOOLEAN;
933 case VOID:
934 return false;
935 case BOT:
936 return isSubtype(t, s);
937 default:
938 throw new AssertionError();
939 }
940 }
942 @Override
943 public Boolean visitWildcardType(WildcardType t, Type s) {
944 return isCastable(upperBound(t), s, warnStack.head);
945 }
947 @Override
948 public Boolean visitClassType(ClassType t, Type s) {
949 if (s.tag == ERROR || s.tag == BOT)
950 return true;
952 if (s.tag == TYPEVAR) {
953 if (isCastable(s.getUpperBound(), t, Warner.noWarnings)) {
954 warnStack.head.warnUnchecked();
955 return true;
956 } else {
957 return false;
958 }
959 }
961 if (t.isCompound()) {
962 Warner oldWarner = warnStack.head;
963 warnStack.head = Warner.noWarnings;
964 if (!visit(supertype(t), s))
965 return false;
966 for (Type intf : interfaces(t)) {
967 if (!visit(intf, s))
968 return false;
969 }
970 if (warnStack.head.unchecked == true)
971 oldWarner.warnUnchecked();
972 return true;
973 }
975 if (s.isCompound()) {
976 // call recursively to reuse the above code
977 return visitClassType((ClassType)s, t);
978 }
980 if (s.tag == CLASS || s.tag == ARRAY) {
981 boolean upcast;
982 if ((upcast = isSubtype(erasure(t), erasure(s)))
983 || isSubtype(erasure(s), erasure(t))) {
984 if (!upcast && s.tag == ARRAY) {
985 if (!isReifiable(s))
986 warnStack.head.warnUnchecked();
987 return true;
988 } else if (s.isRaw()) {
989 return true;
990 } else if (t.isRaw()) {
991 if (!isUnbounded(s))
992 warnStack.head.warnUnchecked();
993 return true;
994 }
995 // Assume |a| <: |b|
996 final Type a = upcast ? t : s;
997 final Type b = upcast ? s : t;
998 final boolean HIGH = true;
999 final boolean LOW = false;
1000 final boolean DONT_REWRITE_TYPEVARS = false;
1001 Type aHigh = rewriteQuantifiers(a, HIGH, DONT_REWRITE_TYPEVARS);
1002 Type aLow = rewriteQuantifiers(a, LOW, DONT_REWRITE_TYPEVARS);
1003 Type bHigh = rewriteQuantifiers(b, HIGH, DONT_REWRITE_TYPEVARS);
1004 Type bLow = rewriteQuantifiers(b, LOW, DONT_REWRITE_TYPEVARS);
1005 Type lowSub = asSub(bLow, aLow.tsym);
1006 Type highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
1007 if (highSub == null) {
1008 final boolean REWRITE_TYPEVARS = true;
1009 aHigh = rewriteQuantifiers(a, HIGH, REWRITE_TYPEVARS);
1010 aLow = rewriteQuantifiers(a, LOW, REWRITE_TYPEVARS);
1011 bHigh = rewriteQuantifiers(b, HIGH, REWRITE_TYPEVARS);
1012 bLow = rewriteQuantifiers(b, LOW, REWRITE_TYPEVARS);
1013 lowSub = asSub(bLow, aLow.tsym);
1014 highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
1015 }
1016 if (highSub != null) {
1017 assert a.tsym == highSub.tsym && a.tsym == lowSub.tsym
1018 : a.tsym + " != " + highSub.tsym + " != " + lowSub.tsym;
1019 if (!disjointTypes(aHigh.allparams(), highSub.allparams())
1020 && !disjointTypes(aHigh.allparams(), lowSub.allparams())
1021 && !disjointTypes(aLow.allparams(), highSub.allparams())
1022 && !disjointTypes(aLow.allparams(), lowSub.allparams())) {
1023 if (upcast ? giveWarning(a, b) :
1024 giveWarning(b, a))
1025 warnStack.head.warnUnchecked();
1026 return true;
1027 }
1028 }
1029 if (isReifiable(s))
1030 return isSubtypeUnchecked(a, b);
1031 else
1032 return isSubtypeUnchecked(a, b, warnStack.head);
1033 }
1035 // Sidecast
1036 if (s.tag == CLASS) {
1037 if ((s.tsym.flags() & INTERFACE) != 0) {
1038 return ((t.tsym.flags() & FINAL) == 0)
1039 ? sideCast(t, s, warnStack.head)
1040 : sideCastFinal(t, s, warnStack.head);
1041 } else if ((t.tsym.flags() & INTERFACE) != 0) {
1042 return ((s.tsym.flags() & FINAL) == 0)
1043 ? sideCast(t, s, warnStack.head)
1044 : sideCastFinal(t, s, warnStack.head);
1045 } else {
1046 // unrelated class types
1047 return false;
1048 }
1049 }
1050 }
1051 return false;
1052 }
1054 @Override
1055 public Boolean visitArrayType(ArrayType t, Type s) {
1056 switch (s.tag) {
1057 case ERROR:
1058 case BOT:
1059 return true;
1060 case TYPEVAR:
1061 if (isCastable(s, t, Warner.noWarnings)) {
1062 warnStack.head.warnUnchecked();
1063 return true;
1064 } else {
1065 return false;
1066 }
1067 case CLASS:
1068 return isSubtype(t, s);
1069 case ARRAY:
1070 if (elemtype(t).tag <= lastBaseTag) {
1071 return elemtype(t).tag == elemtype(s).tag;
1072 } else {
1073 return visit(elemtype(t), elemtype(s));
1074 }
1075 default:
1076 return false;
1077 }
1078 }
1080 @Override
1081 public Boolean visitTypeVar(TypeVar t, Type s) {
1082 switch (s.tag) {
1083 case ERROR:
1084 case BOT:
1085 return true;
1086 case TYPEVAR:
1087 if (isSubtype(t, s)) {
1088 return true;
1089 } else if (isCastable(t.bound, s, Warner.noWarnings)) {
1090 warnStack.head.warnUnchecked();
1091 return true;
1092 } else {
1093 return false;
1094 }
1095 default:
1096 return isCastable(t.bound, s, warnStack.head);
1097 }
1098 }
1100 @Override
1101 public Boolean visitErrorType(ErrorType t, Type s) {
1102 return true;
1103 }
1104 };
1105 // </editor-fold>
1107 // <editor-fold defaultstate="collapsed" desc="disjointTypes">
1108 public boolean disjointTypes(List<Type> ts, List<Type> ss) {
1109 while (ts.tail != null && ss.tail != null) {
1110 if (disjointType(ts.head, ss.head)) return true;
1111 ts = ts.tail;
1112 ss = ss.tail;
1113 }
1114 return false;
1115 }
1117 /**
1118 * Two types or wildcards are considered disjoint if it can be
1119 * proven that no type can be contained in both. It is
1120 * conservative in that it is allowed to say that two types are
1121 * not disjoint, even though they actually are.
1122 *
1123 * The type C<X> is castable to C<Y> exactly if X and Y are not
1124 * disjoint.
1125 */
1126 public boolean disjointType(Type t, Type s) {
1127 return disjointType.visit(t, s);
1128 }
1129 // where
1130 private TypeRelation disjointType = new TypeRelation() {
1132 private Set<TypePair> cache = new HashSet<TypePair>();
1134 public Boolean visitType(Type t, Type s) {
1135 if (s.tag == WILDCARD)
1136 return visit(s, t);
1137 else
1138 return notSoftSubtypeRecursive(t, s) || notSoftSubtypeRecursive(s, t);
1139 }
1141 private boolean isCastableRecursive(Type t, Type s) {
1142 TypePair pair = new TypePair(t, s);
1143 if (cache.add(pair)) {
1144 try {
1145 return Types.this.isCastable(t, s);
1146 } finally {
1147 cache.remove(pair);
1148 }
1149 } else {
1150 return true;
1151 }
1152 }
1154 private boolean notSoftSubtypeRecursive(Type t, Type s) {
1155 TypePair pair = new TypePair(t, s);
1156 if (cache.add(pair)) {
1157 try {
1158 return Types.this.notSoftSubtype(t, s);
1159 } finally {
1160 cache.remove(pair);
1161 }
1162 } else {
1163 return false;
1164 }
1165 }
1167 @Override
1168 public Boolean visitWildcardType(WildcardType t, Type s) {
1169 if (t.isUnbound())
1170 return false;
1172 if (s.tag != WILDCARD) {
1173 if (t.isExtendsBound())
1174 return notSoftSubtypeRecursive(s, t.type);
1175 else // isSuperBound()
1176 return notSoftSubtypeRecursive(t.type, s);
1177 }
1179 if (s.isUnbound())
1180 return false;
1182 if (t.isExtendsBound()) {
1183 if (s.isExtendsBound())
1184 return !isCastableRecursive(t.type, upperBound(s));
1185 else if (s.isSuperBound())
1186 return notSoftSubtypeRecursive(lowerBound(s), t.type);
1187 } else if (t.isSuperBound()) {
1188 if (s.isExtendsBound())
1189 return notSoftSubtypeRecursive(t.type, upperBound(s));
1190 }
1191 return false;
1192 }
1193 };
1194 // </editor-fold>
1196 // <editor-fold defaultstate="collapsed" desc="lowerBoundArgtypes">
1197 /**
1198 * Returns the lower bounds of the formals of a method.
1199 */
1200 public List<Type> lowerBoundArgtypes(Type t) {
1201 return map(t.getParameterTypes(), lowerBoundMapping);
1202 }
1203 private final Mapping lowerBoundMapping = new Mapping("lowerBound") {
1204 public Type apply(Type t) {
1205 return lowerBound(t);
1206 }
1207 };
1208 // </editor-fold>
1210 // <editor-fold defaultstate="collapsed" desc="notSoftSubtype">
1211 /**
1212 * This relation answers the question: is impossible that
1213 * something of type `t' can be a subtype of `s'? This is
1214 * different from the question "is `t' not a subtype of `s'?"
1215 * when type variables are involved: Integer is not a subtype of T
1216 * where <T extends Number> but it is not true that Integer cannot
1217 * possibly be a subtype of T.
1218 */
1219 public boolean notSoftSubtype(Type t, Type s) {
1220 if (t == s) return false;
1221 if (t.tag == TYPEVAR) {
1222 TypeVar tv = (TypeVar) t;
1223 if (s.tag == TYPEVAR)
1224 s = s.getUpperBound();
1225 return !isCastable(tv.bound,
1226 s,
1227 Warner.noWarnings);
1228 }
1229 if (s.tag != WILDCARD)
1230 s = upperBound(s);
1231 if (s.tag == TYPEVAR)
1232 s = s.getUpperBound();
1234 return !isSubtype(t, s);
1235 }
1236 // </editor-fold>
1238 // <editor-fold defaultstate="collapsed" desc="isReifiable">
1239 public boolean isReifiable(Type t) {
1240 return isReifiable.visit(t);
1241 }
1242 // where
1243 private UnaryVisitor<Boolean> isReifiable = new UnaryVisitor<Boolean>() {
1245 public Boolean visitType(Type t, Void ignored) {
1246 return true;
1247 }
1249 @Override
1250 public Boolean visitClassType(ClassType t, Void ignored) {
1251 if (!t.isParameterized())
1252 return true;
1254 for (Type param : t.allparams()) {
1255 if (!param.isUnbound())
1256 return false;
1257 }
1258 return true;
1259 }
1261 @Override
1262 public Boolean visitArrayType(ArrayType t, Void ignored) {
1263 return visit(t.elemtype);
1264 }
1266 @Override
1267 public Boolean visitTypeVar(TypeVar t, Void ignored) {
1268 return false;
1269 }
1270 };
1271 // </editor-fold>
1273 // <editor-fold defaultstate="collapsed" desc="Array Utils">
1274 public boolean isArray(Type t) {
1275 while (t.tag == WILDCARD)
1276 t = upperBound(t);
1277 return t.tag == ARRAY;
1278 }
1280 /**
1281 * The element type of an array.
1282 */
1283 public Type elemtype(Type t) {
1284 switch (t.tag) {
1285 case WILDCARD:
1286 return elemtype(upperBound(t));
1287 case ARRAY:
1288 return ((ArrayType)t).elemtype;
1289 case FORALL:
1290 return elemtype(((ForAll)t).qtype);
1291 case ERROR:
1292 return t;
1293 default:
1294 return null;
1295 }
1296 }
1298 /**
1299 * Mapping to take element type of an arraytype
1300 */
1301 private Mapping elemTypeFun = new Mapping ("elemTypeFun") {
1302 public Type apply(Type t) { return elemtype(t); }
1303 };
1305 /**
1306 * The number of dimensions of an array type.
1307 */
1308 public int dimensions(Type t) {
1309 int result = 0;
1310 while (t.tag == ARRAY) {
1311 result++;
1312 t = elemtype(t);
1313 }
1314 return result;
1315 }
1316 // </editor-fold>
1318 // <editor-fold defaultstate="collapsed" desc="asSuper">
1319 /**
1320 * Return the (most specific) base type of t that starts with the
1321 * given symbol. If none exists, return null.
1322 *
1323 * @param t a type
1324 * @param sym a symbol
1325 */
1326 public Type asSuper(Type t, Symbol sym) {
1327 return asSuper.visit(t, sym);
1328 }
1329 // where
1330 private SimpleVisitor<Type,Symbol> asSuper = new SimpleVisitor<Type,Symbol>() {
1332 public Type visitType(Type t, Symbol sym) {
1333 return null;
1334 }
1336 @Override
1337 public Type visitClassType(ClassType t, Symbol sym) {
1338 if (t.tsym == sym)
1339 return t;
1341 Type st = supertype(t);
1342 if (st.tag == CLASS || st.tag == TYPEVAR || st.tag == ERROR) {
1343 Type x = asSuper(st, sym);
1344 if (x != null)
1345 return x;
1346 }
1347 if ((sym.flags() & INTERFACE) != 0) {
1348 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
1349 Type x = asSuper(l.head, sym);
1350 if (x != null)
1351 return x;
1352 }
1353 }
1354 return null;
1355 }
1357 @Override
1358 public Type visitArrayType(ArrayType t, Symbol sym) {
1359 return isSubtype(t, sym.type) ? sym.type : null;
1360 }
1362 @Override
1363 public Type visitTypeVar(TypeVar t, Symbol sym) {
1364 if (t.tsym == sym)
1365 return t;
1366 else
1367 return asSuper(t.bound, sym);
1368 }
1370 @Override
1371 public Type visitErrorType(ErrorType t, Symbol sym) {
1372 return t;
1373 }
1374 };
1376 /**
1377 * Return the base type of t or any of its outer types that starts
1378 * with the given symbol. If none exists, return null.
1379 *
1380 * @param t a type
1381 * @param sym a symbol
1382 */
1383 public Type asOuterSuper(Type t, Symbol sym) {
1384 switch (t.tag) {
1385 case CLASS:
1386 do {
1387 Type s = asSuper(t, sym);
1388 if (s != null) return s;
1389 t = t.getEnclosingType();
1390 } while (t.tag == CLASS);
1391 return null;
1392 case ARRAY:
1393 return isSubtype(t, sym.type) ? sym.type : null;
1394 case TYPEVAR:
1395 return asSuper(t, sym);
1396 case ERROR:
1397 return t;
1398 default:
1399 return null;
1400 }
1401 }
1403 /**
1404 * Return the base type of t or any of its enclosing types that
1405 * starts with the given symbol. If none exists, return null.
1406 *
1407 * @param t a type
1408 * @param sym a symbol
1409 */
1410 public Type asEnclosingSuper(Type t, Symbol sym) {
1411 switch (t.tag) {
1412 case CLASS:
1413 do {
1414 Type s = asSuper(t, sym);
1415 if (s != null) return s;
1416 Type outer = t.getEnclosingType();
1417 t = (outer.tag == CLASS) ? outer :
1418 (t.tsym.owner.enclClass() != null) ? t.tsym.owner.enclClass().type :
1419 Type.noType;
1420 } while (t.tag == CLASS);
1421 return null;
1422 case ARRAY:
1423 return isSubtype(t, sym.type) ? sym.type : null;
1424 case TYPEVAR:
1425 return asSuper(t, sym);
1426 case ERROR:
1427 return t;
1428 default:
1429 return null;
1430 }
1431 }
1432 // </editor-fold>
1434 // <editor-fold defaultstate="collapsed" desc="memberType">
1435 /**
1436 * The type of given symbol, seen as a member of t.
1437 *
1438 * @param t a type
1439 * @param sym a symbol
1440 */
1441 public Type memberType(Type t, Symbol sym) {
1442 return (sym.flags() & STATIC) != 0
1443 ? sym.type
1444 : memberType.visit(t, sym);
1445 }
1446 // where
1447 private SimpleVisitor<Type,Symbol> memberType = new SimpleVisitor<Type,Symbol>() {
1449 public Type visitType(Type t, Symbol sym) {
1450 return sym.type;
1451 }
1453 @Override
1454 public Type visitWildcardType(WildcardType t, Symbol sym) {
1455 return memberType(upperBound(t), sym);
1456 }
1458 @Override
1459 public Type visitClassType(ClassType t, Symbol sym) {
1460 Symbol owner = sym.owner;
1461 long flags = sym.flags();
1462 if (((flags & STATIC) == 0) && owner.type.isParameterized()) {
1463 Type base = asOuterSuper(t, owner);
1464 //if t is an intersection type T = CT & I1 & I2 ... & In
1465 //its supertypes CT, I1, ... In might contain wildcards
1466 //so we need to go through capture conversion
1467 base = t.isCompound() ? capture(base) : base;
1468 if (base != null) {
1469 List<Type> ownerParams = owner.type.allparams();
1470 List<Type> baseParams = base.allparams();
1471 if (ownerParams.nonEmpty()) {
1472 if (baseParams.isEmpty()) {
1473 // then base is a raw type
1474 return erasure(sym.type);
1475 } else {
1476 return subst(sym.type, ownerParams, baseParams);
1477 }
1478 }
1479 }
1480 }
1481 return sym.type;
1482 }
1484 @Override
1485 public Type visitTypeVar(TypeVar t, Symbol sym) {
1486 return memberType(t.bound, sym);
1487 }
1489 @Override
1490 public Type visitErrorType(ErrorType t, Symbol sym) {
1491 return t;
1492 }
1493 };
1494 // </editor-fold>
1496 // <editor-fold defaultstate="collapsed" desc="isAssignable">
1497 public boolean isAssignable(Type t, Type s) {
1498 return isAssignable(t, s, Warner.noWarnings);
1499 }
1501 /**
1502 * Is t assignable to s?<br>
1503 * Equivalent to subtype except for constant values and raw
1504 * types.<br>
1505 * (not defined for Method and ForAll types)
1506 */
1507 public boolean isAssignable(Type t, Type s, Warner warn) {
1508 if (t.tag == ERROR)
1509 return true;
1510 if (t.tag <= INT && t.constValue() != null) {
1511 int value = ((Number)t.constValue()).intValue();
1512 switch (s.tag) {
1513 case BYTE:
1514 if (Byte.MIN_VALUE <= value && value <= Byte.MAX_VALUE)
1515 return true;
1516 break;
1517 case CHAR:
1518 if (Character.MIN_VALUE <= value && value <= Character.MAX_VALUE)
1519 return true;
1520 break;
1521 case SHORT:
1522 if (Short.MIN_VALUE <= value && value <= Short.MAX_VALUE)
1523 return true;
1524 break;
1525 case INT:
1526 return true;
1527 case CLASS:
1528 switch (unboxedType(s).tag) {
1529 case BYTE:
1530 case CHAR:
1531 case SHORT:
1532 return isAssignable(t, unboxedType(s), warn);
1533 }
1534 break;
1535 }
1536 }
1537 return isConvertible(t, s, warn);
1538 }
1539 // </editor-fold>
1541 // <editor-fold defaultstate="collapsed" desc="erasure">
1542 /**
1543 * The erasure of t {@code |t|} -- the type that results when all
1544 * type parameters in t are deleted.
1545 */
1546 public Type erasure(Type t) {
1547 return erasure(t, false);
1548 }
1549 //where
1550 private Type erasure(Type t, boolean recurse) {
1551 if (t.tag <= lastBaseTag)
1552 return t; /* fast special case */
1553 else
1554 return erasure.visit(t, recurse);
1555 }
1556 // where
1557 private SimpleVisitor<Type, Boolean> erasure = new SimpleVisitor<Type, Boolean>() {
1558 public Type visitType(Type t, Boolean recurse) {
1559 if (t.tag <= lastBaseTag)
1560 return t; /*fast special case*/
1561 else
1562 return t.map(recurse ? erasureRecFun : erasureFun);
1563 }
1565 @Override
1566 public Type visitWildcardType(WildcardType t, Boolean recurse) {
1567 return erasure(upperBound(t), recurse);
1568 }
1570 @Override
1571 public Type visitClassType(ClassType t, Boolean recurse) {
1572 Type erased = t.tsym.erasure(Types.this);
1573 if (recurse) {
1574 erased = new ErasedClassType(erased.getEnclosingType(),erased.tsym);
1575 }
1576 return erased;
1577 }
1579 @Override
1580 public Type visitTypeVar(TypeVar t, Boolean recurse) {
1581 return erasure(t.bound, recurse);
1582 }
1584 @Override
1585 public Type visitErrorType(ErrorType t, Boolean recurse) {
1586 return t;
1587 }
1588 };
1590 private Mapping erasureFun = new Mapping ("erasure") {
1591 public Type apply(Type t) { return erasure(t); }
1592 };
1594 private Mapping erasureRecFun = new Mapping ("erasureRecursive") {
1595 public Type apply(Type t) { return erasureRecursive(t); }
1596 };
1598 public List<Type> erasure(List<Type> ts) {
1599 return Type.map(ts, erasureFun);
1600 }
1602 public Type erasureRecursive(Type t) {
1603 return erasure(t, true);
1604 }
1606 public List<Type> erasureRecursive(List<Type> ts) {
1607 return Type.map(ts, erasureRecFun);
1608 }
1609 // </editor-fold>
1611 // <editor-fold defaultstate="collapsed" desc="makeCompoundType">
1612 /**
1613 * Make a compound type from non-empty list of types
1614 *
1615 * @param bounds the types from which the compound type is formed
1616 * @param supertype is objectType if all bounds are interfaces,
1617 * null otherwise.
1618 */
1619 public Type makeCompoundType(List<Type> bounds,
1620 Type supertype) {
1621 ClassSymbol bc =
1622 new ClassSymbol(ABSTRACT|PUBLIC|SYNTHETIC|COMPOUND|ACYCLIC,
1623 Type.moreInfo
1624 ? names.fromString(bounds.toString())
1625 : names.empty,
1626 syms.noSymbol);
1627 if (bounds.head.tag == TYPEVAR)
1628 // error condition, recover
1629 bc.erasure_field = syms.objectType;
1630 else
1631 bc.erasure_field = erasure(bounds.head);
1632 bc.members_field = new Scope(bc);
1633 ClassType bt = (ClassType)bc.type;
1634 bt.allparams_field = List.nil();
1635 if (supertype != null) {
1636 bt.supertype_field = supertype;
1637 bt.interfaces_field = bounds;
1638 } else {
1639 bt.supertype_field = bounds.head;
1640 bt.interfaces_field = bounds.tail;
1641 }
1642 assert bt.supertype_field.tsym.completer != null
1643 || !bt.supertype_field.isInterface()
1644 : bt.supertype_field;
1645 return bt;
1646 }
1648 /**
1649 * Same as {@link #makeCompoundType(List,Type)}, except that the
1650 * second parameter is computed directly. Note that this might
1651 * cause a symbol completion. Hence, this version of
1652 * makeCompoundType may not be called during a classfile read.
1653 */
1654 public Type makeCompoundType(List<Type> bounds) {
1655 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1656 supertype(bounds.head) : null;
1657 return makeCompoundType(bounds, supertype);
1658 }
1660 /**
1661 * A convenience wrapper for {@link #makeCompoundType(List)}; the
1662 * arguments are converted to a list and passed to the other
1663 * method. Note that this might cause a symbol completion.
1664 * Hence, this version of makeCompoundType may not be called
1665 * during a classfile read.
1666 */
1667 public Type makeCompoundType(Type bound1, Type bound2) {
1668 return makeCompoundType(List.of(bound1, bound2));
1669 }
1670 // </editor-fold>
1672 // <editor-fold defaultstate="collapsed" desc="supertype">
1673 public Type supertype(Type t) {
1674 return supertype.visit(t);
1675 }
1676 // where
1677 private UnaryVisitor<Type> supertype = new UnaryVisitor<Type>() {
1679 public Type visitType(Type t, Void ignored) {
1680 // A note on wildcards: there is no good way to
1681 // determine a supertype for a super bounded wildcard.
1682 return null;
1683 }
1685 @Override
1686 public Type visitClassType(ClassType t, Void ignored) {
1687 if (t.supertype_field == null) {
1688 Type supertype = ((ClassSymbol)t.tsym).getSuperclass();
1689 // An interface has no superclass; its supertype is Object.
1690 if (t.isInterface())
1691 supertype = ((ClassType)t.tsym.type).supertype_field;
1692 if (t.supertype_field == null) {
1693 List<Type> actuals = classBound(t).allparams();
1694 List<Type> formals = t.tsym.type.allparams();
1695 if (t.hasErasedSupertypes()) {
1696 t.supertype_field = erasureRecursive(supertype);
1697 } else if (formals.nonEmpty()) {
1698 t.supertype_field = subst(supertype, formals, actuals);
1699 }
1700 else {
1701 t.supertype_field = supertype;
1702 }
1703 }
1704 }
1705 return t.supertype_field;
1706 }
1708 /**
1709 * The supertype is always a class type. If the type
1710 * variable's bounds start with a class type, this is also
1711 * the supertype. Otherwise, the supertype is
1712 * java.lang.Object.
1713 */
1714 @Override
1715 public Type visitTypeVar(TypeVar t, Void ignored) {
1716 if (t.bound.tag == TYPEVAR ||
1717 (!t.bound.isCompound() && !t.bound.isInterface())) {
1718 return t.bound;
1719 } else {
1720 return supertype(t.bound);
1721 }
1722 }
1724 @Override
1725 public Type visitArrayType(ArrayType t, Void ignored) {
1726 if (t.elemtype.isPrimitive() || isSameType(t.elemtype, syms.objectType))
1727 return arraySuperType();
1728 else
1729 return new ArrayType(supertype(t.elemtype), t.tsym);
1730 }
1732 @Override
1733 public Type visitErrorType(ErrorType t, Void ignored) {
1734 return t;
1735 }
1736 };
1737 // </editor-fold>
1739 // <editor-fold defaultstate="collapsed" desc="interfaces">
1740 /**
1741 * Return the interfaces implemented by this class.
1742 */
1743 public List<Type> interfaces(Type t) {
1744 return interfaces.visit(t);
1745 }
1746 // where
1747 private UnaryVisitor<List<Type>> interfaces = new UnaryVisitor<List<Type>>() {
1749 public List<Type> visitType(Type t, Void ignored) {
1750 return List.nil();
1751 }
1753 @Override
1754 public List<Type> visitClassType(ClassType t, Void ignored) {
1755 if (t.interfaces_field == null) {
1756 List<Type> interfaces = ((ClassSymbol)t.tsym).getInterfaces();
1757 if (t.interfaces_field == null) {
1758 // If t.interfaces_field is null, then t must
1759 // be a parameterized type (not to be confused
1760 // with a generic type declaration).
1761 // Terminology:
1762 // Parameterized type: List<String>
1763 // Generic type declaration: class List<E> { ... }
1764 // So t corresponds to List<String> and
1765 // t.tsym.type corresponds to List<E>.
1766 // The reason t must be parameterized type is
1767 // that completion will happen as a side
1768 // effect of calling
1769 // ClassSymbol.getInterfaces. Since
1770 // t.interfaces_field is null after
1771 // completion, we can assume that t is not the
1772 // type of a class/interface declaration.
1773 assert t != t.tsym.type : t.toString();
1774 List<Type> actuals = t.allparams();
1775 List<Type> formals = t.tsym.type.allparams();
1776 if (t.hasErasedSupertypes()) {
1777 t.interfaces_field = erasureRecursive(interfaces);
1778 } else if (formals.nonEmpty()) {
1779 t.interfaces_field =
1780 upperBounds(subst(interfaces, formals, actuals));
1781 }
1782 else {
1783 t.interfaces_field = interfaces;
1784 }
1785 }
1786 }
1787 return t.interfaces_field;
1788 }
1790 @Override
1791 public List<Type> visitTypeVar(TypeVar t, Void ignored) {
1792 if (t.bound.isCompound())
1793 return interfaces(t.bound);
1795 if (t.bound.isInterface())
1796 return List.of(t.bound);
1798 return List.nil();
1799 }
1800 };
1801 // </editor-fold>
1803 // <editor-fold defaultstate="collapsed" desc="isDerivedRaw">
1804 Map<Type,Boolean> isDerivedRawCache = new HashMap<Type,Boolean>();
1806 public boolean isDerivedRaw(Type t) {
1807 Boolean result = isDerivedRawCache.get(t);
1808 if (result == null) {
1809 result = isDerivedRawInternal(t);
1810 isDerivedRawCache.put(t, result);
1811 }
1812 return result;
1813 }
1815 public boolean isDerivedRawInternal(Type t) {
1816 if (t.isErroneous())
1817 return false;
1818 return
1819 t.isRaw() ||
1820 supertype(t) != null && isDerivedRaw(supertype(t)) ||
1821 isDerivedRaw(interfaces(t));
1822 }
1824 public boolean isDerivedRaw(List<Type> ts) {
1825 List<Type> l = ts;
1826 while (l.nonEmpty() && !isDerivedRaw(l.head)) l = l.tail;
1827 return l.nonEmpty();
1828 }
1829 // </editor-fold>
1831 // <editor-fold defaultstate="collapsed" desc="setBounds">
1832 /**
1833 * Set the bounds field of the given type variable to reflect a
1834 * (possibly multiple) list of bounds.
1835 * @param t a type variable
1836 * @param bounds the bounds, must be nonempty
1837 * @param supertype is objectType if all bounds are interfaces,
1838 * null otherwise.
1839 */
1840 public void setBounds(TypeVar t, List<Type> bounds, Type supertype) {
1841 if (bounds.tail.isEmpty())
1842 t.bound = bounds.head;
1843 else
1844 t.bound = makeCompoundType(bounds, supertype);
1845 t.rank_field = -1;
1846 }
1848 /**
1849 * Same as {@link #setBounds(Type.TypeVar,List,Type)}, except that
1850 * third parameter is computed directly. Note that this test
1851 * might cause a symbol completion. Hence, this version of
1852 * setBounds may not be called during a classfile read.
1853 */
1854 public void setBounds(TypeVar t, List<Type> bounds) {
1855 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1856 supertype(bounds.head) : null;
1857 setBounds(t, bounds, supertype);
1858 t.rank_field = -1;
1859 }
1860 // </editor-fold>
1862 // <editor-fold defaultstate="collapsed" desc="getBounds">
1863 /**
1864 * Return list of bounds of the given type variable.
1865 */
1866 public List<Type> getBounds(TypeVar t) {
1867 if (t.bound.isErroneous() || !t.bound.isCompound())
1868 return List.of(t.bound);
1869 else if ((erasure(t).tsym.flags() & INTERFACE) == 0)
1870 return interfaces(t).prepend(supertype(t));
1871 else
1872 // No superclass was given in bounds.
1873 // In this case, supertype is Object, erasure is first interface.
1874 return interfaces(t);
1875 }
1876 // </editor-fold>
1878 // <editor-fold defaultstate="collapsed" desc="classBound">
1879 /**
1880 * If the given type is a (possibly selected) type variable,
1881 * return the bounding class of this type, otherwise return the
1882 * type itself.
1883 */
1884 public Type classBound(Type t) {
1885 return classBound.visit(t);
1886 }
1887 // where
1888 private UnaryVisitor<Type> classBound = new UnaryVisitor<Type>() {
1890 public Type visitType(Type t, Void ignored) {
1891 return t;
1892 }
1894 @Override
1895 public Type visitClassType(ClassType t, Void ignored) {
1896 Type outer1 = classBound(t.getEnclosingType());
1897 if (outer1 != t.getEnclosingType())
1898 return new ClassType(outer1, t.getTypeArguments(), t.tsym);
1899 else
1900 return t;
1901 }
1903 @Override
1904 public Type visitTypeVar(TypeVar t, Void ignored) {
1905 return classBound(supertype(t));
1906 }
1908 @Override
1909 public Type visitErrorType(ErrorType t, Void ignored) {
1910 return t;
1911 }
1912 };
1913 // </editor-fold>
1915 // <editor-fold defaultstate="collapsed" desc="sub signature / override equivalence">
1916 /**
1917 * Returns true iff the first signature is a <em>sub
1918 * signature</em> of the other. This is <b>not</b> an equivalence
1919 * relation.
1920 *
1921 * @see "The Java Language Specification, Third Ed. (8.4.2)."
1922 * @see #overrideEquivalent(Type t, Type s)
1923 * @param t first signature (possibly raw).
1924 * @param s second signature (could be subjected to erasure).
1925 * @return true if t is a sub signature of s.
1926 */
1927 public boolean isSubSignature(Type t, Type s) {
1928 return hasSameArgs(t, s) || hasSameArgs(t, erasure(s));
1929 }
1931 /**
1932 * Returns true iff these signatures are related by <em>override
1933 * equivalence</em>. This is the natural extension of
1934 * isSubSignature to an equivalence relation.
1935 *
1936 * @see "The Java Language Specification, Third Ed. (8.4.2)."
1937 * @see #isSubSignature(Type t, Type s)
1938 * @param t a signature (possible raw, could be subjected to
1939 * erasure).
1940 * @param s a signature (possible raw, could be subjected to
1941 * erasure).
1942 * @return true if either argument is a sub signature of the other.
1943 */
1944 public boolean overrideEquivalent(Type t, Type s) {
1945 return hasSameArgs(t, s) ||
1946 hasSameArgs(t, erasure(s)) || hasSameArgs(erasure(t), s);
1947 }
1949 /**
1950 * Does t have the same arguments as s? It is assumed that both
1951 * types are (possibly polymorphic) method types. Monomorphic
1952 * method types "have the same arguments", if their argument lists
1953 * are equal. Polymorphic method types "have the same arguments",
1954 * if they have the same arguments after renaming all type
1955 * variables of one to corresponding type variables in the other,
1956 * where correspondence is by position in the type parameter list.
1957 */
1958 public boolean hasSameArgs(Type t, Type s) {
1959 return hasSameArgs.visit(t, s);
1960 }
1961 // where
1962 private TypeRelation hasSameArgs = new TypeRelation() {
1964 public Boolean visitType(Type t, Type s) {
1965 throw new AssertionError();
1966 }
1968 @Override
1969 public Boolean visitMethodType(MethodType t, Type s) {
1970 return s.tag == METHOD
1971 && containsTypeEquivalent(t.argtypes, s.getParameterTypes());
1972 }
1974 @Override
1975 public Boolean visitForAll(ForAll t, Type s) {
1976 if (s.tag != FORALL)
1977 return false;
1979 ForAll forAll = (ForAll)s;
1980 return hasSameBounds(t, forAll)
1981 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
1982 }
1984 @Override
1985 public Boolean visitErrorType(ErrorType t, Type s) {
1986 return false;
1987 }
1988 };
1989 // </editor-fold>
1991 // <editor-fold defaultstate="collapsed" desc="subst">
1992 public List<Type> subst(List<Type> ts,
1993 List<Type> from,
1994 List<Type> to) {
1995 return new Subst(from, to).subst(ts);
1996 }
1998 /**
1999 * Substitute all occurrences of a type in `from' with the
2000 * corresponding type in `to' in 't'. Match lists `from' and `to'
2001 * from the right: If lists have different length, discard leading
2002 * elements of the longer list.
2003 */
2004 public Type subst(Type t, List<Type> from, List<Type> to) {
2005 return new Subst(from, to).subst(t);
2006 }
2008 private class Subst extends UnaryVisitor<Type> {
2009 List<Type> from;
2010 List<Type> to;
2012 public Subst(List<Type> from, List<Type> to) {
2013 int fromLength = from.length();
2014 int toLength = to.length();
2015 while (fromLength > toLength) {
2016 fromLength--;
2017 from = from.tail;
2018 }
2019 while (fromLength < toLength) {
2020 toLength--;
2021 to = to.tail;
2022 }
2023 this.from = from;
2024 this.to = to;
2025 }
2027 Type subst(Type t) {
2028 if (from.tail == null)
2029 return t;
2030 else
2031 return visit(t);
2032 }
2034 List<Type> subst(List<Type> ts) {
2035 if (from.tail == null)
2036 return ts;
2037 boolean wild = false;
2038 if (ts.nonEmpty() && from.nonEmpty()) {
2039 Type head1 = subst(ts.head);
2040 List<Type> tail1 = subst(ts.tail);
2041 if (head1 != ts.head || tail1 != ts.tail)
2042 return tail1.prepend(head1);
2043 }
2044 return ts;
2045 }
2047 public Type visitType(Type t, Void ignored) {
2048 return t;
2049 }
2051 @Override
2052 public Type visitMethodType(MethodType t, Void ignored) {
2053 List<Type> argtypes = subst(t.argtypes);
2054 Type restype = subst(t.restype);
2055 List<Type> thrown = subst(t.thrown);
2056 if (argtypes == t.argtypes &&
2057 restype == t.restype &&
2058 thrown == t.thrown)
2059 return t;
2060 else
2061 return new MethodType(argtypes, restype, thrown, t.tsym);
2062 }
2064 @Override
2065 public Type visitTypeVar(TypeVar t, Void ignored) {
2066 for (List<Type> from = this.from, to = this.to;
2067 from.nonEmpty();
2068 from = from.tail, to = to.tail) {
2069 if (t == from.head) {
2070 return to.head.withTypeVar(t);
2071 }
2072 }
2073 return t;
2074 }
2076 @Override
2077 public Type visitClassType(ClassType t, Void ignored) {
2078 if (!t.isCompound()) {
2079 List<Type> typarams = t.getTypeArguments();
2080 List<Type> typarams1 = subst(typarams);
2081 Type outer = t.getEnclosingType();
2082 Type outer1 = subst(outer);
2083 if (typarams1 == typarams && outer1 == outer)
2084 return t;
2085 else
2086 return new ClassType(outer1, typarams1, t.tsym);
2087 } else {
2088 Type st = subst(supertype(t));
2089 List<Type> is = upperBounds(subst(interfaces(t)));
2090 if (st == supertype(t) && is == interfaces(t))
2091 return t;
2092 else
2093 return makeCompoundType(is.prepend(st));
2094 }
2095 }
2097 @Override
2098 public Type visitWildcardType(WildcardType t, Void ignored) {
2099 Type bound = t.type;
2100 if (t.kind != BoundKind.UNBOUND)
2101 bound = subst(bound);
2102 if (bound == t.type) {
2103 return t;
2104 } else {
2105 if (t.isExtendsBound() && bound.isExtendsBound())
2106 bound = upperBound(bound);
2107 return new WildcardType(bound, t.kind, syms.boundClass, t.bound);
2108 }
2109 }
2111 @Override
2112 public Type visitArrayType(ArrayType t, Void ignored) {
2113 Type elemtype = subst(t.elemtype);
2114 if (elemtype == t.elemtype)
2115 return t;
2116 else
2117 return new ArrayType(upperBound(elemtype), t.tsym);
2118 }
2120 @Override
2121 public Type visitForAll(ForAll t, Void ignored) {
2122 List<Type> tvars1 = substBounds(t.tvars, from, to);
2123 Type qtype1 = subst(t.qtype);
2124 if (tvars1 == t.tvars && qtype1 == t.qtype) {
2125 return t;
2126 } else if (tvars1 == t.tvars) {
2127 return new ForAll(tvars1, qtype1);
2128 } else {
2129 return new ForAll(tvars1, Types.this.subst(qtype1, t.tvars, tvars1));
2130 }
2131 }
2133 @Override
2134 public Type visitErrorType(ErrorType t, Void ignored) {
2135 return t;
2136 }
2137 }
2139 public List<Type> substBounds(List<Type> tvars,
2140 List<Type> from,
2141 List<Type> to) {
2142 if (tvars.isEmpty())
2143 return tvars;
2144 ListBuffer<Type> newBoundsBuf = lb();
2145 boolean changed = false;
2146 // calculate new bounds
2147 for (Type t : tvars) {
2148 TypeVar tv = (TypeVar) t;
2149 Type bound = subst(tv.bound, from, to);
2150 if (bound != tv.bound)
2151 changed = true;
2152 newBoundsBuf.append(bound);
2153 }
2154 if (!changed)
2155 return tvars;
2156 ListBuffer<Type> newTvars = lb();
2157 // create new type variables without bounds
2158 for (Type t : tvars) {
2159 newTvars.append(new TypeVar(t.tsym, null, syms.botType));
2160 }
2161 // the new bounds should use the new type variables in place
2162 // of the old
2163 List<Type> newBounds = newBoundsBuf.toList();
2164 from = tvars;
2165 to = newTvars.toList();
2166 for (; !newBounds.isEmpty(); newBounds = newBounds.tail) {
2167 newBounds.head = subst(newBounds.head, from, to);
2168 }
2169 newBounds = newBoundsBuf.toList();
2170 // set the bounds of new type variables to the new bounds
2171 for (Type t : newTvars.toList()) {
2172 TypeVar tv = (TypeVar) t;
2173 tv.bound = newBounds.head;
2174 newBounds = newBounds.tail;
2175 }
2176 return newTvars.toList();
2177 }
2179 public TypeVar substBound(TypeVar t, List<Type> from, List<Type> to) {
2180 Type bound1 = subst(t.bound, from, to);
2181 if (bound1 == t.bound)
2182 return t;
2183 else {
2184 // create new type variable without bounds
2185 TypeVar tv = new TypeVar(t.tsym, null, syms.botType);
2186 // the new bound should use the new type variable in place
2187 // of the old
2188 tv.bound = subst(bound1, List.<Type>of(t), List.<Type>of(tv));
2189 return tv;
2190 }
2191 }
2192 // </editor-fold>
2194 // <editor-fold defaultstate="collapsed" desc="hasSameBounds">
2195 /**
2196 * Does t have the same bounds for quantified variables as s?
2197 */
2198 boolean hasSameBounds(ForAll t, ForAll s) {
2199 List<Type> l1 = t.tvars;
2200 List<Type> l2 = s.tvars;
2201 while (l1.nonEmpty() && l2.nonEmpty() &&
2202 isSameType(l1.head.getUpperBound(),
2203 subst(l2.head.getUpperBound(),
2204 s.tvars,
2205 t.tvars))) {
2206 l1 = l1.tail;
2207 l2 = l2.tail;
2208 }
2209 return l1.isEmpty() && l2.isEmpty();
2210 }
2211 // </editor-fold>
2213 // <editor-fold defaultstate="collapsed" desc="newInstances">
2214 /** Create new vector of type variables from list of variables
2215 * changing all recursive bounds from old to new list.
2216 */
2217 public List<Type> newInstances(List<Type> tvars) {
2218 List<Type> tvars1 = Type.map(tvars, newInstanceFun);
2219 for (List<Type> l = tvars1; l.nonEmpty(); l = l.tail) {
2220 TypeVar tv = (TypeVar) l.head;
2221 tv.bound = subst(tv.bound, tvars, tvars1);
2222 }
2223 return tvars1;
2224 }
2225 static private Mapping newInstanceFun = new Mapping("newInstanceFun") {
2226 public Type apply(Type t) { return new TypeVar(t.tsym, t.getUpperBound(), t.getLowerBound()); }
2227 };
2228 // </editor-fold>
2230 // <editor-fold defaultstate="collapsed" desc="createErrorType">
2231 public Type createErrorType(Type originalType) {
2232 return new ErrorType(originalType, syms.errSymbol);
2233 }
2235 public Type createErrorType(ClassSymbol c, Type originalType) {
2236 return new ErrorType(c, originalType);
2237 }
2239 public Type createErrorType(Name name, TypeSymbol container, Type originalType) {
2240 return new ErrorType(name, container, originalType);
2241 }
2242 // </editor-fold>
2244 // <editor-fold defaultstate="collapsed" desc="rank">
2245 /**
2246 * The rank of a class is the length of the longest path between
2247 * the class and java.lang.Object in the class inheritance
2248 * graph. Undefined for all but reference types.
2249 */
2250 public int rank(Type t) {
2251 switch(t.tag) {
2252 case CLASS: {
2253 ClassType cls = (ClassType)t;
2254 if (cls.rank_field < 0) {
2255 Name fullname = cls.tsym.getQualifiedName();
2256 if (fullname == names.java_lang_Object)
2257 cls.rank_field = 0;
2258 else {
2259 int r = rank(supertype(cls));
2260 for (List<Type> l = interfaces(cls);
2261 l.nonEmpty();
2262 l = l.tail) {
2263 if (rank(l.head) > r)
2264 r = rank(l.head);
2265 }
2266 cls.rank_field = r + 1;
2267 }
2268 }
2269 return cls.rank_field;
2270 }
2271 case TYPEVAR: {
2272 TypeVar tvar = (TypeVar)t;
2273 if (tvar.rank_field < 0) {
2274 int r = rank(supertype(tvar));
2275 for (List<Type> l = interfaces(tvar);
2276 l.nonEmpty();
2277 l = l.tail) {
2278 if (rank(l.head) > r) r = rank(l.head);
2279 }
2280 tvar.rank_field = r + 1;
2281 }
2282 return tvar.rank_field;
2283 }
2284 case ERROR:
2285 return 0;
2286 default:
2287 throw new AssertionError();
2288 }
2289 }
2290 // </editor-fold>
2292 /**
2293 * Helper method for generating a string representation of a given type
2294 * accordingly to a given locale
2295 */
2296 public String toString(Type t, Locale locale) {
2297 return Printer.createStandardPrinter(messages).visit(t, locale);
2298 }
2300 /**
2301 * Helper method for generating a string representation of a given type
2302 * accordingly to a given locale
2303 */
2304 public String toString(Symbol t, Locale locale) {
2305 return Printer.createStandardPrinter(messages).visit(t, locale);
2306 }
2308 // <editor-fold defaultstate="collapsed" desc="toString">
2309 /**
2310 * This toString is slightly more descriptive than the one on Type.
2311 *
2312 * @deprecated Types.toString(Type t, Locale l) provides better support
2313 * for localization
2314 */
2315 @Deprecated
2316 public String toString(Type t) {
2317 if (t.tag == FORALL) {
2318 ForAll forAll = (ForAll)t;
2319 return typaramsString(forAll.tvars) + forAll.qtype;
2320 }
2321 return "" + t;
2322 }
2323 // where
2324 private String typaramsString(List<Type> tvars) {
2325 StringBuffer s = new StringBuffer();
2326 s.append('<');
2327 boolean first = true;
2328 for (Type t : tvars) {
2329 if (!first) s.append(", ");
2330 first = false;
2331 appendTyparamString(((TypeVar)t), s);
2332 }
2333 s.append('>');
2334 return s.toString();
2335 }
2336 private void appendTyparamString(TypeVar t, StringBuffer buf) {
2337 buf.append(t);
2338 if (t.bound == null ||
2339 t.bound.tsym.getQualifiedName() == names.java_lang_Object)
2340 return;
2341 buf.append(" extends "); // Java syntax; no need for i18n
2342 Type bound = t.bound;
2343 if (!bound.isCompound()) {
2344 buf.append(bound);
2345 } else if ((erasure(t).tsym.flags() & INTERFACE) == 0) {
2346 buf.append(supertype(t));
2347 for (Type intf : interfaces(t)) {
2348 buf.append('&');
2349 buf.append(intf);
2350 }
2351 } else {
2352 // No superclass was given in bounds.
2353 // In this case, supertype is Object, erasure is first interface.
2354 boolean first = true;
2355 for (Type intf : interfaces(t)) {
2356 if (!first) buf.append('&');
2357 first = false;
2358 buf.append(intf);
2359 }
2360 }
2361 }
2362 // </editor-fold>
2364 // <editor-fold defaultstate="collapsed" desc="Determining least upper bounds of types">
2365 /**
2366 * A cache for closures.
2367 *
2368 * <p>A closure is a list of all the supertypes and interfaces of
2369 * a class or interface type, ordered by ClassSymbol.precedes
2370 * (that is, subclasses come first, arbitrary but fixed
2371 * otherwise).
2372 */
2373 private Map<Type,List<Type>> closureCache = new HashMap<Type,List<Type>>();
2375 /**
2376 * Returns the closure of a class or interface type.
2377 */
2378 public List<Type> closure(Type t) {
2379 List<Type> cl = closureCache.get(t);
2380 if (cl == null) {
2381 Type st = supertype(t);
2382 if (!t.isCompound()) {
2383 if (st.tag == CLASS) {
2384 cl = insert(closure(st), t);
2385 } else if (st.tag == TYPEVAR) {
2386 cl = closure(st).prepend(t);
2387 } else {
2388 cl = List.of(t);
2389 }
2390 } else {
2391 cl = closure(supertype(t));
2392 }
2393 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail)
2394 cl = union(cl, closure(l.head));
2395 closureCache.put(t, cl);
2396 }
2397 return cl;
2398 }
2400 /**
2401 * Insert a type in a closure
2402 */
2403 public List<Type> insert(List<Type> cl, Type t) {
2404 if (cl.isEmpty() || t.tsym.precedes(cl.head.tsym, this)) {
2405 return cl.prepend(t);
2406 } else if (cl.head.tsym.precedes(t.tsym, this)) {
2407 return insert(cl.tail, t).prepend(cl.head);
2408 } else {
2409 return cl;
2410 }
2411 }
2413 /**
2414 * Form the union of two closures
2415 */
2416 public List<Type> union(List<Type> cl1, List<Type> cl2) {
2417 if (cl1.isEmpty()) {
2418 return cl2;
2419 } else if (cl2.isEmpty()) {
2420 return cl1;
2421 } else if (cl1.head.tsym.precedes(cl2.head.tsym, this)) {
2422 return union(cl1.tail, cl2).prepend(cl1.head);
2423 } else if (cl2.head.tsym.precedes(cl1.head.tsym, this)) {
2424 return union(cl1, cl2.tail).prepend(cl2.head);
2425 } else {
2426 return union(cl1.tail, cl2.tail).prepend(cl1.head);
2427 }
2428 }
2430 /**
2431 * Intersect two closures
2432 */
2433 public List<Type> intersect(List<Type> cl1, List<Type> cl2) {
2434 if (cl1 == cl2)
2435 return cl1;
2436 if (cl1.isEmpty() || cl2.isEmpty())
2437 return List.nil();
2438 if (cl1.head.tsym.precedes(cl2.head.tsym, this))
2439 return intersect(cl1.tail, cl2);
2440 if (cl2.head.tsym.precedes(cl1.head.tsym, this))
2441 return intersect(cl1, cl2.tail);
2442 if (isSameType(cl1.head, cl2.head))
2443 return intersect(cl1.tail, cl2.tail).prepend(cl1.head);
2444 if (cl1.head.tsym == cl2.head.tsym &&
2445 cl1.head.tag == CLASS && cl2.head.tag == CLASS) {
2446 if (cl1.head.isParameterized() && cl2.head.isParameterized()) {
2447 Type merge = merge(cl1.head,cl2.head);
2448 return intersect(cl1.tail, cl2.tail).prepend(merge);
2449 }
2450 if (cl1.head.isRaw() || cl2.head.isRaw())
2451 return intersect(cl1.tail, cl2.tail).prepend(erasure(cl1.head));
2452 }
2453 return intersect(cl1.tail, cl2.tail);
2454 }
2455 // where
2456 class TypePair {
2457 final Type t1;
2458 final Type t2;
2459 TypePair(Type t1, Type t2) {
2460 this.t1 = t1;
2461 this.t2 = t2;
2462 }
2463 @Override
2464 public int hashCode() {
2465 return 127 * Types.this.hashCode(t1) + Types.this.hashCode(t2);
2466 }
2467 @Override
2468 public boolean equals(Object obj) {
2469 if (!(obj instanceof TypePair))
2470 return false;
2471 TypePair typePair = (TypePair)obj;
2472 return isSameType(t1, typePair.t1)
2473 && isSameType(t2, typePair.t2);
2474 }
2475 }
2476 Set<TypePair> mergeCache = new HashSet<TypePair>();
2477 private Type merge(Type c1, Type c2) {
2478 ClassType class1 = (ClassType) c1;
2479 List<Type> act1 = class1.getTypeArguments();
2480 ClassType class2 = (ClassType) c2;
2481 List<Type> act2 = class2.getTypeArguments();
2482 ListBuffer<Type> merged = new ListBuffer<Type>();
2483 List<Type> typarams = class1.tsym.type.getTypeArguments();
2485 while (act1.nonEmpty() && act2.nonEmpty() && typarams.nonEmpty()) {
2486 if (containsType(act1.head, act2.head)) {
2487 merged.append(act1.head);
2488 } else if (containsType(act2.head, act1.head)) {
2489 merged.append(act2.head);
2490 } else {
2491 TypePair pair = new TypePair(c1, c2);
2492 Type m;
2493 if (mergeCache.add(pair)) {
2494 m = new WildcardType(lub(upperBound(act1.head),
2495 upperBound(act2.head)),
2496 BoundKind.EXTENDS,
2497 syms.boundClass);
2498 mergeCache.remove(pair);
2499 } else {
2500 m = new WildcardType(syms.objectType,
2501 BoundKind.UNBOUND,
2502 syms.boundClass);
2503 }
2504 merged.append(m.withTypeVar(typarams.head));
2505 }
2506 act1 = act1.tail;
2507 act2 = act2.tail;
2508 typarams = typarams.tail;
2509 }
2510 assert(act1.isEmpty() && act2.isEmpty() && typarams.isEmpty());
2511 return new ClassType(class1.getEnclosingType(), merged.toList(), class1.tsym);
2512 }
2514 /**
2515 * Return the minimum type of a closure, a compound type if no
2516 * unique minimum exists.
2517 */
2518 private Type compoundMin(List<Type> cl) {
2519 if (cl.isEmpty()) return syms.objectType;
2520 List<Type> compound = closureMin(cl);
2521 if (compound.isEmpty())
2522 return null;
2523 else if (compound.tail.isEmpty())
2524 return compound.head;
2525 else
2526 return makeCompoundType(compound);
2527 }
2529 /**
2530 * Return the minimum types of a closure, suitable for computing
2531 * compoundMin or glb.
2532 */
2533 private List<Type> closureMin(List<Type> cl) {
2534 ListBuffer<Type> classes = lb();
2535 ListBuffer<Type> interfaces = lb();
2536 while (!cl.isEmpty()) {
2537 Type current = cl.head;
2538 if (current.isInterface())
2539 interfaces.append(current);
2540 else
2541 classes.append(current);
2542 ListBuffer<Type> candidates = lb();
2543 for (Type t : cl.tail) {
2544 if (!isSubtypeNoCapture(current, t))
2545 candidates.append(t);
2546 }
2547 cl = candidates.toList();
2548 }
2549 return classes.appendList(interfaces).toList();
2550 }
2552 /**
2553 * Return the least upper bound of pair of types. if the lub does
2554 * not exist return null.
2555 */
2556 public Type lub(Type t1, Type t2) {
2557 return lub(List.of(t1, t2));
2558 }
2560 /**
2561 * Return the least upper bound (lub) of set of types. If the lub
2562 * does not exist return the type of null (bottom).
2563 */
2564 public Type lub(List<Type> ts) {
2565 final int ARRAY_BOUND = 1;
2566 final int CLASS_BOUND = 2;
2567 int boundkind = 0;
2568 for (Type t : ts) {
2569 switch (t.tag) {
2570 case CLASS:
2571 boundkind |= CLASS_BOUND;
2572 break;
2573 case ARRAY:
2574 boundkind |= ARRAY_BOUND;
2575 break;
2576 case TYPEVAR:
2577 do {
2578 t = t.getUpperBound();
2579 } while (t.tag == TYPEVAR);
2580 if (t.tag == ARRAY) {
2581 boundkind |= ARRAY_BOUND;
2582 } else {
2583 boundkind |= CLASS_BOUND;
2584 }
2585 break;
2586 default:
2587 if (t.isPrimitive())
2588 return syms.errType;
2589 }
2590 }
2591 switch (boundkind) {
2592 case 0:
2593 return syms.botType;
2595 case ARRAY_BOUND:
2596 // calculate lub(A[], B[])
2597 List<Type> elements = Type.map(ts, elemTypeFun);
2598 for (Type t : elements) {
2599 if (t.isPrimitive()) {
2600 // if a primitive type is found, then return
2601 // arraySuperType unless all the types are the
2602 // same
2603 Type first = ts.head;
2604 for (Type s : ts.tail) {
2605 if (!isSameType(first, s)) {
2606 // lub(int[], B[]) is Cloneable & Serializable
2607 return arraySuperType();
2608 }
2609 }
2610 // all the array types are the same, return one
2611 // lub(int[], int[]) is int[]
2612 return first;
2613 }
2614 }
2615 // lub(A[], B[]) is lub(A, B)[]
2616 return new ArrayType(lub(elements), syms.arrayClass);
2618 case CLASS_BOUND:
2619 // calculate lub(A, B)
2620 while (ts.head.tag != CLASS && ts.head.tag != TYPEVAR)
2621 ts = ts.tail;
2622 assert !ts.isEmpty();
2623 List<Type> cl = closure(ts.head);
2624 for (Type t : ts.tail) {
2625 if (t.tag == CLASS || t.tag == TYPEVAR)
2626 cl = intersect(cl, closure(t));
2627 }
2628 return compoundMin(cl);
2630 default:
2631 // calculate lub(A, B[])
2632 List<Type> classes = List.of(arraySuperType());
2633 for (Type t : ts) {
2634 if (t.tag != ARRAY) // Filter out any arrays
2635 classes = classes.prepend(t);
2636 }
2637 // lub(A, B[]) is lub(A, arraySuperType)
2638 return lub(classes);
2639 }
2640 }
2641 // where
2642 private Type arraySuperType = null;
2643 private Type arraySuperType() {
2644 // initialized lazily to avoid problems during compiler startup
2645 if (arraySuperType == null) {
2646 synchronized (this) {
2647 if (arraySuperType == null) {
2648 // JLS 10.8: all arrays implement Cloneable and Serializable.
2649 arraySuperType = makeCompoundType(List.of(syms.serializableType,
2650 syms.cloneableType),
2651 syms.objectType);
2652 }
2653 }
2654 }
2655 return arraySuperType;
2656 }
2657 // </editor-fold>
2659 // <editor-fold defaultstate="collapsed" desc="Greatest lower bound">
2660 public Type glb(List<Type> ts) {
2661 Type t1 = ts.head;
2662 for (Type t2 : ts.tail) {
2663 if (t1.isErroneous())
2664 return t1;
2665 t1 = glb(t1, t2);
2666 }
2667 return t1;
2668 }
2669 //where
2670 public Type glb(Type t, Type s) {
2671 if (s == null)
2672 return t;
2673 else if (isSubtypeNoCapture(t, s))
2674 return t;
2675 else if (isSubtypeNoCapture(s, t))
2676 return s;
2678 List<Type> closure = union(closure(t), closure(s));
2679 List<Type> bounds = closureMin(closure);
2681 if (bounds.isEmpty()) { // length == 0
2682 return syms.objectType;
2683 } else if (bounds.tail.isEmpty()) { // length == 1
2684 return bounds.head;
2685 } else { // length > 1
2686 int classCount = 0;
2687 for (Type bound : bounds)
2688 if (!bound.isInterface())
2689 classCount++;
2690 if (classCount > 1)
2691 return createErrorType(t);
2692 }
2693 return makeCompoundType(bounds);
2694 }
2695 // </editor-fold>
2697 // <editor-fold defaultstate="collapsed" desc="hashCode">
2698 /**
2699 * Compute a hash code on a type.
2700 */
2701 public static int hashCode(Type t) {
2702 return hashCode.visit(t);
2703 }
2704 // where
2705 private static final UnaryVisitor<Integer> hashCode = new UnaryVisitor<Integer>() {
2707 public Integer visitType(Type t, Void ignored) {
2708 return t.tag;
2709 }
2711 @Override
2712 public Integer visitClassType(ClassType t, Void ignored) {
2713 int result = visit(t.getEnclosingType());
2714 result *= 127;
2715 result += t.tsym.flatName().hashCode();
2716 for (Type s : t.getTypeArguments()) {
2717 result *= 127;
2718 result += visit(s);
2719 }
2720 return result;
2721 }
2723 @Override
2724 public Integer visitWildcardType(WildcardType t, Void ignored) {
2725 int result = t.kind.hashCode();
2726 if (t.type != null) {
2727 result *= 127;
2728 result += visit(t.type);
2729 }
2730 return result;
2731 }
2733 @Override
2734 public Integer visitArrayType(ArrayType t, Void ignored) {
2735 return visit(t.elemtype) + 12;
2736 }
2738 @Override
2739 public Integer visitTypeVar(TypeVar t, Void ignored) {
2740 return System.identityHashCode(t.tsym);
2741 }
2743 @Override
2744 public Integer visitUndetVar(UndetVar t, Void ignored) {
2745 return System.identityHashCode(t);
2746 }
2748 @Override
2749 public Integer visitErrorType(ErrorType t, Void ignored) {
2750 return 0;
2751 }
2752 };
2753 // </editor-fold>
2755 // <editor-fold defaultstate="collapsed" desc="Return-Type-Substitutable">
2756 /**
2757 * Does t have a result that is a subtype of the result type of s,
2758 * suitable for covariant returns? It is assumed that both types
2759 * are (possibly polymorphic) method types. Monomorphic method
2760 * types are handled in the obvious way. Polymorphic method types
2761 * require renaming all type variables of one to corresponding
2762 * type variables in the other, where correspondence is by
2763 * position in the type parameter list. */
2764 public boolean resultSubtype(Type t, Type s, Warner warner) {
2765 List<Type> tvars = t.getTypeArguments();
2766 List<Type> svars = s.getTypeArguments();
2767 Type tres = t.getReturnType();
2768 Type sres = subst(s.getReturnType(), svars, tvars);
2769 return covariantReturnType(tres, sres, warner);
2770 }
2772 /**
2773 * Return-Type-Substitutable.
2774 * @see <a href="http://java.sun.com/docs/books/jls/">The Java
2775 * Language Specification, Third Ed. (8.4.5)</a>
2776 */
2777 public boolean returnTypeSubstitutable(Type r1, Type r2) {
2778 if (hasSameArgs(r1, r2))
2779 return resultSubtype(r1, r2, Warner.noWarnings);
2780 else
2781 return covariantReturnType(r1.getReturnType(),
2782 erasure(r2.getReturnType()),
2783 Warner.noWarnings);
2784 }
2786 public boolean returnTypeSubstitutable(Type r1,
2787 Type r2, Type r2res,
2788 Warner warner) {
2789 if (isSameType(r1.getReturnType(), r2res))
2790 return true;
2791 if (r1.getReturnType().isPrimitive() || r2res.isPrimitive())
2792 return false;
2794 if (hasSameArgs(r1, r2))
2795 return covariantReturnType(r1.getReturnType(), r2res, warner);
2796 if (!source.allowCovariantReturns())
2797 return false;
2798 if (isSubtypeUnchecked(r1.getReturnType(), r2res, warner))
2799 return true;
2800 if (!isSubtype(r1.getReturnType(), erasure(r2res)))
2801 return false;
2802 warner.warnUnchecked();
2803 return true;
2804 }
2806 /**
2807 * Is t an appropriate return type in an overrider for a
2808 * method that returns s?
2809 */
2810 public boolean covariantReturnType(Type t, Type s, Warner warner) {
2811 return
2812 isSameType(t, s) ||
2813 source.allowCovariantReturns() &&
2814 !t.isPrimitive() &&
2815 !s.isPrimitive() &&
2816 isAssignable(t, s, warner);
2817 }
2818 // </editor-fold>
2820 // <editor-fold defaultstate="collapsed" desc="Box/unbox support">
2821 /**
2822 * Return the class that boxes the given primitive.
2823 */
2824 public ClassSymbol boxedClass(Type t) {
2825 return reader.enterClass(syms.boxedName[t.tag]);
2826 }
2828 /**
2829 * Return the primitive type corresponding to a boxed type.
2830 */
2831 public Type unboxedType(Type t) {
2832 if (allowBoxing) {
2833 for (int i=0; i<syms.boxedName.length; i++) {
2834 Name box = syms.boxedName[i];
2835 if (box != null &&
2836 asSuper(t, reader.enterClass(box)) != null)
2837 return syms.typeOfTag[i];
2838 }
2839 }
2840 return Type.noType;
2841 }
2842 // </editor-fold>
2844 // <editor-fold defaultstate="collapsed" desc="Capture conversion">
2845 /*
2846 * JLS 3rd Ed. 5.1.10 Capture Conversion:
2847 *
2848 * Let G name a generic type declaration with n formal type
2849 * parameters A1 ... An with corresponding bounds U1 ... Un. There
2850 * exists a capture conversion from G<T1 ... Tn> to G<S1 ... Sn>,
2851 * where, for 1 <= i <= n:
2852 *
2853 * + If Ti is a wildcard type argument (4.5.1) of the form ? then
2854 * Si is a fresh type variable whose upper bound is
2855 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is the null
2856 * type.
2857 *
2858 * + If Ti is a wildcard type argument of the form ? extends Bi,
2859 * then Si is a fresh type variable whose upper bound is
2860 * glb(Bi, Ui[A1 := S1, ..., An := Sn]) and whose lower bound is
2861 * the null type, where glb(V1,... ,Vm) is V1 & ... & Vm. It is
2862 * a compile-time error if for any two classes (not interfaces)
2863 * Vi and Vj,Vi is not a subclass of Vj or vice versa.
2864 *
2865 * + If Ti is a wildcard type argument of the form ? super Bi,
2866 * then Si is a fresh type variable whose upper bound is
2867 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is Bi.
2868 *
2869 * + Otherwise, Si = Ti.
2870 *
2871 * Capture conversion on any type other than a parameterized type
2872 * (4.5) acts as an identity conversion (5.1.1). Capture
2873 * conversions never require a special action at run time and
2874 * therefore never throw an exception at run time.
2875 *
2876 * Capture conversion is not applied recursively.
2877 */
2878 /**
2879 * Capture conversion as specified by JLS 3rd Ed.
2880 */
2882 public List<Type> capture(List<Type> ts) {
2883 List<Type> buf = List.nil();
2884 for (Type t : ts) {
2885 buf = buf.prepend(capture(t));
2886 }
2887 return buf.reverse();
2888 }
2889 public Type capture(Type t) {
2890 if (t.tag != CLASS)
2891 return t;
2892 ClassType cls = (ClassType)t;
2893 if (cls.isRaw() || !cls.isParameterized())
2894 return cls;
2896 ClassType G = (ClassType)cls.asElement().asType();
2897 List<Type> A = G.getTypeArguments();
2898 List<Type> T = cls.getTypeArguments();
2899 List<Type> S = freshTypeVariables(T);
2901 List<Type> currentA = A;
2902 List<Type> currentT = T;
2903 List<Type> currentS = S;
2904 boolean captured = false;
2905 while (!currentA.isEmpty() &&
2906 !currentT.isEmpty() &&
2907 !currentS.isEmpty()) {
2908 if (currentS.head != currentT.head) {
2909 captured = true;
2910 WildcardType Ti = (WildcardType)currentT.head;
2911 Type Ui = currentA.head.getUpperBound();
2912 CapturedType Si = (CapturedType)currentS.head;
2913 if (Ui == null)
2914 Ui = syms.objectType;
2915 switch (Ti.kind) {
2916 case UNBOUND:
2917 Si.bound = subst(Ui, A, S);
2918 Si.lower = syms.botType;
2919 break;
2920 case EXTENDS:
2921 Si.bound = glb(Ti.getExtendsBound(), subst(Ui, A, S));
2922 Si.lower = syms.botType;
2923 break;
2924 case SUPER:
2925 Si.bound = subst(Ui, A, S);
2926 Si.lower = Ti.getSuperBound();
2927 break;
2928 }
2929 if (Si.bound == Si.lower)
2930 currentS.head = Si.bound;
2931 }
2932 currentA = currentA.tail;
2933 currentT = currentT.tail;
2934 currentS = currentS.tail;
2935 }
2936 if (!currentA.isEmpty() || !currentT.isEmpty() || !currentS.isEmpty())
2937 return erasure(t); // some "rare" type involved
2939 if (captured)
2940 return new ClassType(cls.getEnclosingType(), S, cls.tsym);
2941 else
2942 return t;
2943 }
2944 // where
2945 public List<Type> freshTypeVariables(List<Type> types) {
2946 ListBuffer<Type> result = lb();
2947 for (Type t : types) {
2948 if (t.tag == WILDCARD) {
2949 Type bound = ((WildcardType)t).getExtendsBound();
2950 if (bound == null)
2951 bound = syms.objectType;
2952 result.append(new CapturedType(capturedName,
2953 syms.noSymbol,
2954 bound,
2955 syms.botType,
2956 (WildcardType)t));
2957 } else {
2958 result.append(t);
2959 }
2960 }
2961 return result.toList();
2962 }
2963 // </editor-fold>
2965 // <editor-fold defaultstate="collapsed" desc="Internal utility methods">
2966 private List<Type> upperBounds(List<Type> ss) {
2967 if (ss.isEmpty()) return ss;
2968 Type head = upperBound(ss.head);
2969 List<Type> tail = upperBounds(ss.tail);
2970 if (head != ss.head || tail != ss.tail)
2971 return tail.prepend(head);
2972 else
2973 return ss;
2974 }
2976 private boolean sideCast(Type from, Type to, Warner warn) {
2977 // We are casting from type $from$ to type $to$, which are
2978 // non-final unrelated types. This method
2979 // tries to reject a cast by transferring type parameters
2980 // from $to$ to $from$ by common superinterfaces.
2981 boolean reverse = false;
2982 Type target = to;
2983 if ((to.tsym.flags() & INTERFACE) == 0) {
2984 assert (from.tsym.flags() & INTERFACE) != 0;
2985 reverse = true;
2986 to = from;
2987 from = target;
2988 }
2989 List<Type> commonSupers = superClosure(to, erasure(from));
2990 boolean giveWarning = commonSupers.isEmpty();
2991 // The arguments to the supers could be unified here to
2992 // get a more accurate analysis
2993 while (commonSupers.nonEmpty()) {
2994 Type t1 = asSuper(from, commonSupers.head.tsym);
2995 Type t2 = commonSupers.head; // same as asSuper(to, commonSupers.head.tsym);
2996 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
2997 return false;
2998 giveWarning = giveWarning || (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2));
2999 commonSupers = commonSupers.tail;
3000 }
3001 if (giveWarning && !isReifiable(reverse ? from : to))
3002 warn.warnUnchecked();
3003 if (!source.allowCovariantReturns())
3004 // reject if there is a common method signature with
3005 // incompatible return types.
3006 chk.checkCompatibleAbstracts(warn.pos(), from, to);
3007 return true;
3008 }
3010 private boolean sideCastFinal(Type from, Type to, Warner warn) {
3011 // We are casting from type $from$ to type $to$, which are
3012 // unrelated types one of which is final and the other of
3013 // which is an interface. This method
3014 // tries to reject a cast by transferring type parameters
3015 // from the final class to the interface.
3016 boolean reverse = false;
3017 Type target = to;
3018 if ((to.tsym.flags() & INTERFACE) == 0) {
3019 assert (from.tsym.flags() & INTERFACE) != 0;
3020 reverse = true;
3021 to = from;
3022 from = target;
3023 }
3024 assert (from.tsym.flags() & FINAL) != 0;
3025 Type t1 = asSuper(from, to.tsym);
3026 if (t1 == null) return false;
3027 Type t2 = to;
3028 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
3029 return false;
3030 if (!source.allowCovariantReturns())
3031 // reject if there is a common method signature with
3032 // incompatible return types.
3033 chk.checkCompatibleAbstracts(warn.pos(), from, to);
3034 if (!isReifiable(target) &&
3035 (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2)))
3036 warn.warnUnchecked();
3037 return true;
3038 }
3040 private boolean giveWarning(Type from, Type to) {
3041 Type subFrom = asSub(from, to.tsym);
3042 return to.isParameterized() &&
3043 (!(isUnbounded(to) ||
3044 isSubtype(from, to) ||
3045 ((subFrom != null) && isSameType(subFrom, to))));
3046 }
3048 private List<Type> superClosure(Type t, Type s) {
3049 List<Type> cl = List.nil();
3050 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
3051 if (isSubtype(s, erasure(l.head))) {
3052 cl = insert(cl, l.head);
3053 } else {
3054 cl = union(cl, superClosure(l.head, s));
3055 }
3056 }
3057 return cl;
3058 }
3060 private boolean containsTypeEquivalent(Type t, Type s) {
3061 return
3062 isSameType(t, s) || // shortcut
3063 containsType(t, s) && containsType(s, t);
3064 }
3066 // <editor-fold defaultstate="collapsed" desc="adapt">
3067 /**
3068 * Adapt a type by computing a substitution which maps a source
3069 * type to a target type.
3070 *
3071 * @param source the source type
3072 * @param target the target type
3073 * @param from the type variables of the computed substitution
3074 * @param to the types of the computed substitution.
3075 */
3076 public void adapt(Type source,
3077 Type target,
3078 ListBuffer<Type> from,
3079 ListBuffer<Type> to) throws AdaptFailure {
3080 new Adapter(from, to).adapt(source, target);
3081 }
3083 class Adapter extends SimpleVisitor<Void, Type> {
3085 ListBuffer<Type> from;
3086 ListBuffer<Type> to;
3087 Map<Symbol,Type> mapping;
3089 Adapter(ListBuffer<Type> from, ListBuffer<Type> to) {
3090 this.from = from;
3091 this.to = to;
3092 mapping = new HashMap<Symbol,Type>();
3093 }
3095 public void adapt(Type source, Type target) throws AdaptFailure {
3096 visit(source, target);
3097 List<Type> fromList = from.toList();
3098 List<Type> toList = to.toList();
3099 while (!fromList.isEmpty()) {
3100 Type val = mapping.get(fromList.head.tsym);
3101 if (toList.head != val)
3102 toList.head = val;
3103 fromList = fromList.tail;
3104 toList = toList.tail;
3105 }
3106 }
3108 @Override
3109 public Void visitClassType(ClassType source, Type target) throws AdaptFailure {
3110 if (target.tag == CLASS)
3111 adaptRecursive(source.allparams(), target.allparams());
3112 return null;
3113 }
3115 @Override
3116 public Void visitArrayType(ArrayType source, Type target) throws AdaptFailure {
3117 if (target.tag == ARRAY)
3118 adaptRecursive(elemtype(source), elemtype(target));
3119 return null;
3120 }
3122 @Override
3123 public Void visitWildcardType(WildcardType source, Type target) throws AdaptFailure {
3124 if (source.isExtendsBound())
3125 adaptRecursive(upperBound(source), upperBound(target));
3126 else if (source.isSuperBound())
3127 adaptRecursive(lowerBound(source), lowerBound(target));
3128 return null;
3129 }
3131 @Override
3132 public Void visitTypeVar(TypeVar source, Type target) throws AdaptFailure {
3133 // Check to see if there is
3134 // already a mapping for $source$, in which case
3135 // the old mapping will be merged with the new
3136 Type val = mapping.get(source.tsym);
3137 if (val != null) {
3138 if (val.isSuperBound() && target.isSuperBound()) {
3139 val = isSubtype(lowerBound(val), lowerBound(target))
3140 ? target : val;
3141 } else if (val.isExtendsBound() && target.isExtendsBound()) {
3142 val = isSubtype(upperBound(val), upperBound(target))
3143 ? val : target;
3144 } else if (!isSameType(val, target)) {
3145 throw new AdaptFailure();
3146 }
3147 } else {
3148 val = target;
3149 from.append(source);
3150 to.append(target);
3151 }
3152 mapping.put(source.tsym, val);
3153 return null;
3154 }
3156 @Override
3157 public Void visitType(Type source, Type target) {
3158 return null;
3159 }
3161 private Set<TypePair> cache = new HashSet<TypePair>();
3163 private void adaptRecursive(Type source, Type target) {
3164 TypePair pair = new TypePair(source, target);
3165 if (cache.add(pair)) {
3166 try {
3167 visit(source, target);
3168 } finally {
3169 cache.remove(pair);
3170 }
3171 }
3172 }
3174 private void adaptRecursive(List<Type> source, List<Type> target) {
3175 if (source.length() == target.length()) {
3176 while (source.nonEmpty()) {
3177 adaptRecursive(source.head, target.head);
3178 source = source.tail;
3179 target = target.tail;
3180 }
3181 }
3182 }
3183 }
3185 public static class AdaptFailure extends RuntimeException {
3186 static final long serialVersionUID = -7490231548272701566L;
3187 }
3189 private void adaptSelf(Type t,
3190 ListBuffer<Type> from,
3191 ListBuffer<Type> to) {
3192 try {
3193 //if (t.tsym.type != t)
3194 adapt(t.tsym.type, t, from, to);
3195 } catch (AdaptFailure ex) {
3196 // Adapt should never fail calculating a mapping from
3197 // t.tsym.type to t as there can be no merge problem.
3198 throw new AssertionError(ex);
3199 }
3200 }
3201 // </editor-fold>
3203 /**
3204 * Rewrite all type variables (universal quantifiers) in the given
3205 * type to wildcards (existential quantifiers). This is used to
3206 * determine if a cast is allowed. For example, if high is true
3207 * and {@code T <: Number}, then {@code List<T>} is rewritten to
3208 * {@code List<? extends Number>}. Since {@code List<Integer> <:
3209 * List<? extends Number>} a {@code List<T>} can be cast to {@code
3210 * List<Integer>} with a warning.
3211 * @param t a type
3212 * @param high if true return an upper bound; otherwise a lower
3213 * bound
3214 * @param rewriteTypeVars only rewrite captured wildcards if false;
3215 * otherwise rewrite all type variables
3216 * @return the type rewritten with wildcards (existential
3217 * quantifiers) only
3218 */
3219 private Type rewriteQuantifiers(Type t, boolean high, boolean rewriteTypeVars) {
3220 return new Rewriter(high, rewriteTypeVars).rewrite(t);
3221 }
3223 class Rewriter extends UnaryVisitor<Type> {
3225 boolean high;
3226 boolean rewriteTypeVars;
3228 Rewriter(boolean high, boolean rewriteTypeVars) {
3229 this.high = high;
3230 this.rewriteTypeVars = rewriteTypeVars;
3231 }
3233 Type rewrite(Type t) {
3234 ListBuffer<Type> from = new ListBuffer<Type>();
3235 ListBuffer<Type> to = new ListBuffer<Type>();
3236 adaptSelf(t, from, to);
3237 ListBuffer<Type> rewritten = new ListBuffer<Type>();
3238 List<Type> formals = from.toList();
3239 boolean changed = false;
3240 for (Type arg : to.toList()) {
3241 Type bound = visit(arg);
3242 if (arg != bound) {
3243 changed = true;
3244 bound = high ? makeExtendsWildcard(bound, (TypeVar)formals.head)
3245 : makeSuperWildcard(bound, (TypeVar)formals.head);
3246 }
3247 rewritten.append(bound);
3248 formals = formals.tail;
3249 }
3250 if (changed)
3251 return subst(t.tsym.type, from.toList(), rewritten.toList());
3252 else
3253 return t;
3254 }
3256 public Type visitType(Type t, Void s) {
3257 return high ? upperBound(t) : lowerBound(t);
3258 }
3260 @Override
3261 public Type visitCapturedType(CapturedType t, Void s) {
3262 return visitWildcardType(t.wildcard, null);
3263 }
3265 @Override
3266 public Type visitTypeVar(TypeVar t, Void s) {
3267 if (rewriteTypeVars)
3268 return high ? t.bound : syms.botType;
3269 else
3270 return t;
3271 }
3273 @Override
3274 public Type visitWildcardType(WildcardType t, Void s) {
3275 Type bound = high ? t.getExtendsBound() :
3276 t.getSuperBound();
3277 if (bound == null)
3278 bound = high ? syms.objectType : syms.botType;
3279 return bound;
3280 }
3281 }
3283 /**
3284 * Create a wildcard with the given upper (extends) bound; create
3285 * an unbounded wildcard if bound is Object.
3286 *
3287 * @param bound the upper bound
3288 * @param formal the formal type parameter that will be
3289 * substituted by the wildcard
3290 */
3291 private WildcardType makeExtendsWildcard(Type bound, TypeVar formal) {
3292 if (bound == syms.objectType) {
3293 return new WildcardType(syms.objectType,
3294 BoundKind.UNBOUND,
3295 syms.boundClass,
3296 formal);
3297 } else {
3298 return new WildcardType(bound,
3299 BoundKind.EXTENDS,
3300 syms.boundClass,
3301 formal);
3302 }
3303 }
3305 /**
3306 * Create a wildcard with the given lower (super) bound; create an
3307 * unbounded wildcard if bound is bottom (type of {@code null}).
3308 *
3309 * @param bound the lower bound
3310 * @param formal the formal type parameter that will be
3311 * substituted by the wildcard
3312 */
3313 private WildcardType makeSuperWildcard(Type bound, TypeVar formal) {
3314 if (bound.tag == BOT) {
3315 return new WildcardType(syms.objectType,
3316 BoundKind.UNBOUND,
3317 syms.boundClass,
3318 formal);
3319 } else {
3320 return new WildcardType(bound,
3321 BoundKind.SUPER,
3322 syms.boundClass,
3323 formal);
3324 }
3325 }
3327 /**
3328 * A wrapper for a type that allows use in sets.
3329 */
3330 class SingletonType {
3331 final Type t;
3332 SingletonType(Type t) {
3333 this.t = t;
3334 }
3335 public int hashCode() {
3336 return Types.this.hashCode(t);
3337 }
3338 public boolean equals(Object obj) {
3339 return (obj instanceof SingletonType) &&
3340 isSameType(t, ((SingletonType)obj).t);
3341 }
3342 public String toString() {
3343 return t.toString();
3344 }
3345 }
3346 // </editor-fold>
3348 // <editor-fold defaultstate="collapsed" desc="Visitors">
3349 /**
3350 * A default visitor for types. All visitor methods except
3351 * visitType are implemented by delegating to visitType. Concrete
3352 * subclasses must provide an implementation of visitType and can
3353 * override other methods as needed.
3354 *
3355 * @param <R> the return type of the operation implemented by this
3356 * visitor; use Void if no return type is needed.
3357 * @param <S> the type of the second argument (the first being the
3358 * type itself) of the operation implemented by this visitor; use
3359 * Void if a second argument is not needed.
3360 */
3361 public static abstract class DefaultTypeVisitor<R,S> implements Type.Visitor<R,S> {
3362 final public R visit(Type t, S s) { return t.accept(this, s); }
3363 public R visitClassType(ClassType t, S s) { return visitType(t, s); }
3364 public R visitWildcardType(WildcardType t, S s) { return visitType(t, s); }
3365 public R visitArrayType(ArrayType t, S s) { return visitType(t, s); }
3366 public R visitMethodType(MethodType t, S s) { return visitType(t, s); }
3367 public R visitPackageType(PackageType t, S s) { return visitType(t, s); }
3368 public R visitTypeVar(TypeVar t, S s) { return visitType(t, s); }
3369 public R visitCapturedType(CapturedType t, S s) { return visitType(t, s); }
3370 public R visitForAll(ForAll t, S s) { return visitType(t, s); }
3371 public R visitUndetVar(UndetVar t, S s) { return visitType(t, s); }
3372 public R visitErrorType(ErrorType t, S s) { return visitType(t, s); }
3373 }
3375 /**
3376 * A default visitor for symbols. All visitor methods except
3377 * visitSymbol are implemented by delegating to visitSymbol. Concrete
3378 * subclasses must provide an implementation of visitSymbol and can
3379 * override other methods as needed.
3380 *
3381 * @param <R> the return type of the operation implemented by this
3382 * visitor; use Void if no return type is needed.
3383 * @param <S> the type of the second argument (the first being the
3384 * symbol itself) of the operation implemented by this visitor; use
3385 * Void if a second argument is not needed.
3386 */
3387 public static abstract class DefaultSymbolVisitor<R,S> implements Symbol.Visitor<R,S> {
3388 final public R visit(Symbol s, S arg) { return s.accept(this, arg); }
3389 public R visitClassSymbol(ClassSymbol s, S arg) { return visitSymbol(s, arg); }
3390 public R visitMethodSymbol(MethodSymbol s, S arg) { return visitSymbol(s, arg); }
3391 public R visitOperatorSymbol(OperatorSymbol s, S arg) { return visitSymbol(s, arg); }
3392 public R visitPackageSymbol(PackageSymbol s, S arg) { return visitSymbol(s, arg); }
3393 public R visitTypeSymbol(TypeSymbol s, S arg) { return visitSymbol(s, arg); }
3394 public R visitVarSymbol(VarSymbol s, S arg) { return visitSymbol(s, arg); }
3395 }
3397 /**
3398 * A <em>simple</em> visitor for types. This visitor is simple as
3399 * captured wildcards, for-all types (generic methods), and
3400 * undetermined type variables (part of inference) are hidden.
3401 * Captured wildcards are hidden by treating them as type
3402 * variables and the rest are hidden by visiting their qtypes.
3403 *
3404 * @param <R> the return type of the operation implemented by this
3405 * visitor; use Void if no return type is needed.
3406 * @param <S> the type of the second argument (the first being the
3407 * type itself) of the operation implemented by this visitor; use
3408 * Void if a second argument is not needed.
3409 */
3410 public static abstract class SimpleVisitor<R,S> extends DefaultTypeVisitor<R,S> {
3411 @Override
3412 public R visitCapturedType(CapturedType t, S s) {
3413 return visitTypeVar(t, s);
3414 }
3415 @Override
3416 public R visitForAll(ForAll t, S s) {
3417 return visit(t.qtype, s);
3418 }
3419 @Override
3420 public R visitUndetVar(UndetVar t, S s) {
3421 return visit(t.qtype, s);
3422 }
3423 }
3425 /**
3426 * A plain relation on types. That is a 2-ary function on the
3427 * form Type × Type → Boolean.
3428 * <!-- In plain text: Type x Type -> Boolean -->
3429 */
3430 public static abstract class TypeRelation extends SimpleVisitor<Boolean,Type> {}
3432 /**
3433 * A convenience visitor for implementing operations that only
3434 * require one argument (the type itself), that is, unary
3435 * operations.
3436 *
3437 * @param <R> the return type of the operation implemented by this
3438 * visitor; use Void if no return type is needed.
3439 */
3440 public static abstract class UnaryVisitor<R> extends SimpleVisitor<R,Void> {
3441 final public R visit(Type t) { return t.accept(this, null); }
3442 }
3444 /**
3445 * A visitor for implementing a mapping from types to types. The
3446 * default behavior of this class is to implement the identity
3447 * mapping (mapping a type to itself). This can be overridden in
3448 * subclasses.
3449 *
3450 * @param <S> the type of the second argument (the first being the
3451 * type itself) of this mapping; use Void if a second argument is
3452 * not needed.
3453 */
3454 public static class MapVisitor<S> extends DefaultTypeVisitor<Type,S> {
3455 final public Type visit(Type t) { return t.accept(this, null); }
3456 public Type visitType(Type t, S s) { return t; }
3457 }
3458 // </editor-fold>
3459 }
