Mercurial > jdk8-mips64-public > langtools / file revision
src/share/classes/com/sun/tools/javac/code/Types.java@b4b1f7732289
src/share/classes/com/sun/tools/javac/code/Types.java
Tue, 20 Jan 2009 18:23:13 -0800
- author
- jjg
- date
- Tue, 20 Jan 2009 18:23:13 -0800
- changeset 198
- b4b1f7732289
- parent 196
- 1ca2dc8584e1
- child 202
- 3b2c55b7bd01
- permissions
- -rw-r--r--
6795903: fix latent build warnings in langtools repository
Reviewed-by: darcy
1 /*
2 * Copyright 2003-2008 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
26 package com.sun.tools.javac.code;
28 import java.util.*;
30 import com.sun.tools.javac.util.*;
31 import com.sun.tools.javac.util.List;
33 import com.sun.tools.javac.jvm.ClassReader;
34 import com.sun.tools.javac.comp.Check;
36 import static com.sun.tools.javac.code.Type.*;
37 import static com.sun.tools.javac.code.TypeTags.*;
38 import static com.sun.tools.javac.code.Symbol.*;
39 import static com.sun.tools.javac.code.Flags.*;
40 import static com.sun.tools.javac.code.BoundKind.*;
41 import static com.sun.tools.javac.util.ListBuffer.lb;
43 /**
44 * Utility class containing various operations on types.
45 *
46 * <p>Unless other names are more illustrative, the following naming
47 * conventions should be observed in this file:
48 *
49 * <dl>
50 * <dt>t</dt>
51 * <dd>If the first argument to an operation is a type, it should be named t.</dd>
52 * <dt>s</dt>
53 * <dd>Similarly, if the second argument to an operation is a type, it should be named s.</dd>
54 * <dt>ts</dt>
55 * <dd>If an operations takes a list of types, the first should be named ts.</dd>
56 * <dt>ss</dt>
57 * <dd>A second list of types should be named ss.</dd>
58 * </dl>
59 *
60 * <p><b>This is NOT part of any API supported by Sun Microsystems.
61 * If you write code that depends on this, you do so at your own risk.
62 * This code and its internal interfaces are subject to change or
63 * deletion without notice.</b>
64 */
65 public class Types {
66 protected static final Context.Key<Types> typesKey =
67 new Context.Key<Types>();
69 final Symtab syms;
70 final JavacMessages messages;
71 final Names names;
72 final boolean allowBoxing;
73 final ClassReader reader;
74 final Source source;
75 final Check chk;
76 List<Warner> warnStack = List.nil();
77 final Name capturedName;
79 // <editor-fold defaultstate="collapsed" desc="Instantiating">
80 public static Types instance(Context context) {
81 Types instance = context.get(typesKey);
82 if (instance == null)
83 instance = new Types(context);
84 return instance;
85 }
87 protected Types(Context context) {
88 context.put(typesKey, this);
89 syms = Symtab.instance(context);
90 names = Names.instance(context);
91 allowBoxing = Source.instance(context).allowBoxing();
92 reader = ClassReader.instance(context);
93 source = Source.instance(context);
94 chk = Check.instance(context);
95 capturedName = names.fromString("<captured wildcard>");
96 messages = JavacMessages.instance(context);
97 }
98 // </editor-fold>
100 // <editor-fold defaultstate="collapsed" desc="upperBound">
101 /**
102 * The "rvalue conversion".<br>
103 * The upper bound of most types is the type
104 * itself. Wildcards, on the other hand have upper
105 * and lower bounds.
106 * @param t a type
107 * @return the upper bound of the given type
108 */
109 public Type upperBound(Type t) {
110 return upperBound.visit(t);
111 }
112 // where
113 private final MapVisitor<Void> upperBound = new MapVisitor<Void>() {
115 @Override
116 public Type visitWildcardType(WildcardType t, Void ignored) {
117 if (t.isSuperBound())
118 return t.bound == null ? syms.objectType : t.bound.bound;
119 else
120 return visit(t.type);
121 }
123 @Override
124 public Type visitCapturedType(CapturedType t, Void ignored) {
125 return visit(t.bound);
126 }
127 };
128 // </editor-fold>
130 // <editor-fold defaultstate="collapsed" desc="lowerBound">
131 /**
132 * The "lvalue conversion".<br>
133 * The lower bound of most types is the type
134 * itself. Wildcards, on the other hand have upper
135 * and lower bounds.
136 * @param t a type
137 * @return the lower bound of the given type
138 */
139 public Type lowerBound(Type t) {
140 return lowerBound.visit(t);
141 }
142 // where
143 private final MapVisitor<Void> lowerBound = new MapVisitor<Void>() {
145 @Override
146 public Type visitWildcardType(WildcardType t, Void ignored) {
147 return t.isExtendsBound() ? syms.botType : visit(t.type);
148 }
150 @Override
151 public Type visitCapturedType(CapturedType t, Void ignored) {
152 return visit(t.getLowerBound());
153 }
154 };
155 // </editor-fold>
157 // <editor-fold defaultstate="collapsed" desc="isUnbounded">
158 /**
159 * Checks that all the arguments to a class are unbounded
160 * wildcards or something else that doesn't make any restrictions
161 * on the arguments. If a class isUnbounded, a raw super- or
162 * subclass can be cast to it without a warning.
163 * @param t a type
164 * @return true iff the given type is unbounded or raw
165 */
166 public boolean isUnbounded(Type t) {
167 return isUnbounded.visit(t);
168 }
169 // where
170 private final UnaryVisitor<Boolean> isUnbounded = new UnaryVisitor<Boolean>() {
172 public Boolean visitType(Type t, Void ignored) {
173 return true;
174 }
176 @Override
177 public Boolean visitClassType(ClassType t, Void ignored) {
178 List<Type> parms = t.tsym.type.allparams();
179 List<Type> args = t.allparams();
180 while (parms.nonEmpty()) {
181 WildcardType unb = new WildcardType(syms.objectType,
182 BoundKind.UNBOUND,
183 syms.boundClass,
184 (TypeVar)parms.head);
185 if (!containsType(args.head, unb))
186 return false;
187 parms = parms.tail;
188 args = args.tail;
189 }
190 return true;
191 }
192 };
193 // </editor-fold>
195 // <editor-fold defaultstate="collapsed" desc="asSub">
196 /**
197 * Return the least specific subtype of t that starts with symbol
198 * sym. If none exists, return null. The least specific subtype
199 * is determined as follows:
200 *
201 * <p>If there is exactly one parameterized instance of sym that is a
202 * subtype of t, that parameterized instance is returned.<br>
203 * Otherwise, if the plain type or raw type `sym' is a subtype of
204 * type t, the type `sym' itself is returned. Otherwise, null is
205 * returned.
206 */
207 public Type asSub(Type t, Symbol sym) {
208 return asSub.visit(t, sym);
209 }
210 // where
211 private final SimpleVisitor<Type,Symbol> asSub = new SimpleVisitor<Type,Symbol>() {
213 public Type visitType(Type t, Symbol sym) {
214 return null;
215 }
217 @Override
218 public Type visitClassType(ClassType t, Symbol sym) {
219 if (t.tsym == sym)
220 return t;
221 Type base = asSuper(sym.type, t.tsym);
222 if (base == null)
223 return null;
224 ListBuffer<Type> from = new ListBuffer<Type>();
225 ListBuffer<Type> to = new ListBuffer<Type>();
226 try {
227 adapt(base, t, from, to);
228 } catch (AdaptFailure ex) {
229 return null;
230 }
231 Type res = subst(sym.type, from.toList(), to.toList());
232 if (!isSubtype(res, t))
233 return null;
234 ListBuffer<Type> openVars = new ListBuffer<Type>();
235 for (List<Type> l = sym.type.allparams();
236 l.nonEmpty(); l = l.tail)
237 if (res.contains(l.head) && !t.contains(l.head))
238 openVars.append(l.head);
239 if (openVars.nonEmpty()) {
240 if (t.isRaw()) {
241 // The subtype of a raw type is raw
242 res = erasure(res);
243 } else {
244 // Unbound type arguments default to ?
245 List<Type> opens = openVars.toList();
246 ListBuffer<Type> qs = new ListBuffer<Type>();
247 for (List<Type> iter = opens; iter.nonEmpty(); iter = iter.tail) {
248 qs.append(new WildcardType(syms.objectType, BoundKind.UNBOUND, syms.boundClass, (TypeVar) iter.head));
249 }
250 res = subst(res, opens, qs.toList());
251 }
252 }
253 return res;
254 }
256 @Override
257 public Type visitErrorType(ErrorType t, Symbol sym) {
258 return t;
259 }
260 };
261 // </editor-fold>
263 // <editor-fold defaultstate="collapsed" desc="isConvertible">
264 /**
265 * Is t a subtype of or convertiable via boxing/unboxing
266 * convertions to s?
267 */
268 public boolean isConvertible(Type t, Type s, Warner warn) {
269 boolean tPrimitive = t.isPrimitive();
270 boolean sPrimitive = s.isPrimitive();
271 if (tPrimitive == sPrimitive)
272 return isSubtypeUnchecked(t, s, warn);
273 if (!allowBoxing) return false;
274 return tPrimitive
275 ? isSubtype(boxedClass(t).type, s)
276 : isSubtype(unboxedType(t), s);
277 }
279 /**
280 * Is t a subtype of or convertiable via boxing/unboxing
281 * convertions to s?
282 */
283 public boolean isConvertible(Type t, Type s) {
284 return isConvertible(t, s, Warner.noWarnings);
285 }
286 // </editor-fold>
288 // <editor-fold defaultstate="collapsed" desc="isSubtype">
289 /**
290 * Is t an unchecked subtype of s?
291 */
292 public boolean isSubtypeUnchecked(Type t, Type s) {
293 return isSubtypeUnchecked(t, s, Warner.noWarnings);
294 }
295 /**
296 * Is t an unchecked subtype of s?
297 */
298 public boolean isSubtypeUnchecked(Type t, Type s, Warner warn) {
299 if (t.tag == ARRAY && s.tag == ARRAY) {
300 return (((ArrayType)t).elemtype.tag <= lastBaseTag)
301 ? isSameType(elemtype(t), elemtype(s))
302 : isSubtypeUnchecked(elemtype(t), elemtype(s), warn);
303 } else if (isSubtype(t, s)) {
304 return true;
305 }
306 else if (t.tag == TYPEVAR) {
307 return isSubtypeUnchecked(t.getUpperBound(), s, warn);
308 }
309 else if (s.tag == UNDETVAR) {
310 UndetVar uv = (UndetVar)s;
311 if (uv.inst != null)
312 return isSubtypeUnchecked(t, uv.inst, warn);
313 }
314 else if (!s.isRaw()) {
315 Type t2 = asSuper(t, s.tsym);
316 if (t2 != null && t2.isRaw()) {
317 if (isReifiable(s))
318 warn.silentUnchecked();
319 else
320 warn.warnUnchecked();
321 return true;
322 }
323 }
324 return false;
325 }
327 /**
328 * Is t a subtype of s?<br>
329 * (not defined for Method and ForAll types)
330 */
331 final public boolean isSubtype(Type t, Type s) {
332 return isSubtype(t, s, true);
333 }
334 final public boolean isSubtypeNoCapture(Type t, Type s) {
335 return isSubtype(t, s, false);
336 }
337 public boolean isSubtype(Type t, Type s, boolean capture) {
338 if (t == s)
339 return true;
341 if (s.tag >= firstPartialTag)
342 return isSuperType(s, t);
344 Type lower = lowerBound(s);
345 if (s != lower)
346 return isSubtype(capture ? capture(t) : t, lower, false);
348 return isSubtype.visit(capture ? capture(t) : t, s);
349 }
350 // where
351 private TypeRelation isSubtype = new TypeRelation()
352 {
353 public Boolean visitType(Type t, Type s) {
354 switch (t.tag) {
355 case BYTE: case CHAR:
356 return (t.tag == s.tag ||
357 t.tag + 2 <= s.tag && s.tag <= DOUBLE);
358 case SHORT: case INT: case LONG: case FLOAT: case DOUBLE:
359 return t.tag <= s.tag && s.tag <= DOUBLE;
360 case BOOLEAN: case VOID:
361 return t.tag == s.tag;
362 case TYPEVAR:
363 return isSubtypeNoCapture(t.getUpperBound(), s);
364 case BOT:
365 return
366 s.tag == BOT || s.tag == CLASS ||
367 s.tag == ARRAY || s.tag == TYPEVAR;
368 case NONE:
369 return false;
370 default:
371 throw new AssertionError("isSubtype " + t.tag);
372 }
373 }
375 private Set<TypePair> cache = new HashSet<TypePair>();
377 private boolean containsTypeRecursive(Type t, Type s) {
378 TypePair pair = new TypePair(t, s);
379 if (cache.add(pair)) {
380 try {
381 return containsType(t.getTypeArguments(),
382 s.getTypeArguments());
383 } finally {
384 cache.remove(pair);
385 }
386 } else {
387 return containsType(t.getTypeArguments(),
388 rewriteSupers(s).getTypeArguments());
389 }
390 }
392 private Type rewriteSupers(Type t) {
393 if (!t.isParameterized())
394 return t;
395 ListBuffer<Type> from = lb();
396 ListBuffer<Type> to = lb();
397 adaptSelf(t, from, to);
398 if (from.isEmpty())
399 return t;
400 ListBuffer<Type> rewrite = lb();
401 boolean changed = false;
402 for (Type orig : to.toList()) {
403 Type s = rewriteSupers(orig);
404 if (s.isSuperBound() && !s.isExtendsBound()) {
405 s = new WildcardType(syms.objectType,
406 BoundKind.UNBOUND,
407 syms.boundClass);
408 changed = true;
409 } else if (s != orig) {
410 s = new WildcardType(upperBound(s),
411 BoundKind.EXTENDS,
412 syms.boundClass);
413 changed = true;
414 }
415 rewrite.append(s);
416 }
417 if (changed)
418 return subst(t.tsym.type, from.toList(), rewrite.toList());
419 else
420 return t;
421 }
423 @Override
424 public Boolean visitClassType(ClassType t, Type s) {
425 Type sup = asSuper(t, s.tsym);
426 return sup != null
427 && sup.tsym == s.tsym
428 // You're not allowed to write
429 // Vector<Object> vec = new Vector<String>();
430 // But with wildcards you can write
431 // Vector<? extends Object> vec = new Vector<String>();
432 // which means that subtype checking must be done
433 // here instead of same-type checking (via containsType).
434 && (!s.isParameterized() || containsTypeRecursive(s, sup))
435 && isSubtypeNoCapture(sup.getEnclosingType(),
436 s.getEnclosingType());
437 }
439 @Override
440 public Boolean visitArrayType(ArrayType t, Type s) {
441 if (s.tag == ARRAY) {
442 if (t.elemtype.tag <= lastBaseTag)
443 return isSameType(t.elemtype, elemtype(s));
444 else
445 return isSubtypeNoCapture(t.elemtype, elemtype(s));
446 }
448 if (s.tag == CLASS) {
449 Name sname = s.tsym.getQualifiedName();
450 return sname == names.java_lang_Object
451 || sname == names.java_lang_Cloneable
452 || sname == names.java_io_Serializable;
453 }
455 return false;
456 }
458 @Override
459 public Boolean visitUndetVar(UndetVar t, Type s) {
460 //todo: test against origin needed? or replace with substitution?
461 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
462 return true;
464 if (t.inst != null)
465 return isSubtypeNoCapture(t.inst, s); // TODO: ", warn"?
467 t.hibounds = t.hibounds.prepend(s);
468 return true;
469 }
471 @Override
472 public Boolean visitErrorType(ErrorType t, Type s) {
473 return true;
474 }
475 };
477 /**
478 * Is t a subtype of every type in given list `ts'?<br>
479 * (not defined for Method and ForAll types)<br>
480 * Allows unchecked conversions.
481 */
482 public boolean isSubtypeUnchecked(Type t, List<Type> ts, Warner warn) {
483 for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
484 if (!isSubtypeUnchecked(t, l.head, warn))
485 return false;
486 return true;
487 }
489 /**
490 * Are corresponding elements of ts subtypes of ss? If lists are
491 * of different length, return false.
492 */
493 public boolean isSubtypes(List<Type> ts, List<Type> ss) {
494 while (ts.tail != null && ss.tail != null
495 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
496 isSubtype(ts.head, ss.head)) {
497 ts = ts.tail;
498 ss = ss.tail;
499 }
500 return ts.tail == null && ss.tail == null;
501 /*inlined: ts.isEmpty() && ss.isEmpty();*/
502 }
504 /**
505 * Are corresponding elements of ts subtypes of ss, allowing
506 * unchecked conversions? If lists are of different length,
507 * return false.
508 **/
509 public boolean isSubtypesUnchecked(List<Type> ts, List<Type> ss, Warner warn) {
510 while (ts.tail != null && ss.tail != null
511 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
512 isSubtypeUnchecked(ts.head, ss.head, warn)) {
513 ts = ts.tail;
514 ss = ss.tail;
515 }
516 return ts.tail == null && ss.tail == null;
517 /*inlined: ts.isEmpty() && ss.isEmpty();*/
518 }
519 // </editor-fold>
521 // <editor-fold defaultstate="collapsed" desc="isSuperType">
522 /**
523 * Is t a supertype of s?
524 */
525 public boolean isSuperType(Type t, Type s) {
526 switch (t.tag) {
527 case ERROR:
528 return true;
529 case UNDETVAR: {
530 UndetVar undet = (UndetVar)t;
531 if (t == s ||
532 undet.qtype == s ||
533 s.tag == ERROR ||
534 s.tag == BOT) return true;
535 if (undet.inst != null)
536 return isSubtype(s, undet.inst);
537 undet.lobounds = undet.lobounds.prepend(s);
538 return true;
539 }
540 default:
541 return isSubtype(s, t);
542 }
543 }
544 // </editor-fold>
546 // <editor-fold defaultstate="collapsed" desc="isSameType">
547 /**
548 * Are corresponding elements of the lists the same type? If
549 * lists are of different length, return false.
550 */
551 public boolean isSameTypes(List<Type> ts, List<Type> ss) {
552 while (ts.tail != null && ss.tail != null
553 /*inlined: ts.nonEmpty() && ss.nonEmpty()*/ &&
554 isSameType(ts.head, ss.head)) {
555 ts = ts.tail;
556 ss = ss.tail;
557 }
558 return ts.tail == null && ss.tail == null;
559 /*inlined: ts.isEmpty() && ss.isEmpty();*/
560 }
562 /**
563 * Is t the same type as s?
564 */
565 public boolean isSameType(Type t, Type s) {
566 return isSameType.visit(t, s);
567 }
568 // where
569 private TypeRelation isSameType = new TypeRelation() {
571 public Boolean visitType(Type t, Type s) {
572 if (t == s)
573 return true;
575 if (s.tag >= firstPartialTag)
576 return visit(s, t);
578 switch (t.tag) {
579 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
580 case DOUBLE: case BOOLEAN: case VOID: case BOT: case NONE:
581 return t.tag == s.tag;
582 case TYPEVAR:
583 return s.isSuperBound()
584 && !s.isExtendsBound()
585 && visit(t, upperBound(s));
586 default:
587 throw new AssertionError("isSameType " + t.tag);
588 }
589 }
591 @Override
592 public Boolean visitWildcardType(WildcardType t, Type s) {
593 if (s.tag >= firstPartialTag)
594 return visit(s, t);
595 else
596 return false;
597 }
599 @Override
600 public Boolean visitClassType(ClassType t, Type s) {
601 if (t == s)
602 return true;
604 if (s.tag >= firstPartialTag)
605 return visit(s, t);
607 if (s.isSuperBound() && !s.isExtendsBound())
608 return visit(t, upperBound(s)) && visit(t, lowerBound(s));
610 if (t.isCompound() && s.isCompound()) {
611 if (!visit(supertype(t), supertype(s)))
612 return false;
614 HashSet<SingletonType> set = new HashSet<SingletonType>();
615 for (Type x : interfaces(t))
616 set.add(new SingletonType(x));
617 for (Type x : interfaces(s)) {
618 if (!set.remove(new SingletonType(x)))
619 return false;
620 }
621 return (set.size() == 0);
622 }
623 return t.tsym == s.tsym
624 && visit(t.getEnclosingType(), s.getEnclosingType())
625 && containsTypeEquivalent(t.getTypeArguments(), s.getTypeArguments());
626 }
628 @Override
629 public Boolean visitArrayType(ArrayType t, Type s) {
630 if (t == s)
631 return true;
633 if (s.tag >= firstPartialTag)
634 return visit(s, t);
636 return s.tag == ARRAY
637 && containsTypeEquivalent(t.elemtype, elemtype(s));
638 }
640 @Override
641 public Boolean visitMethodType(MethodType t, Type s) {
642 // isSameType for methods does not take thrown
643 // exceptions into account!
644 return hasSameArgs(t, s) && visit(t.getReturnType(), s.getReturnType());
645 }
647 @Override
648 public Boolean visitPackageType(PackageType t, Type s) {
649 return t == s;
650 }
652 @Override
653 public Boolean visitForAll(ForAll t, Type s) {
654 if (s.tag != FORALL)
655 return false;
657 ForAll forAll = (ForAll)s;
658 return hasSameBounds(t, forAll)
659 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
660 }
662 @Override
663 public Boolean visitUndetVar(UndetVar t, Type s) {
664 if (s.tag == WILDCARD)
665 // FIXME, this might be leftovers from before capture conversion
666 return false;
668 if (t == s || t.qtype == s || s.tag == ERROR || s.tag == UNKNOWN)
669 return true;
671 if (t.inst != null)
672 return visit(t.inst, s);
674 t.inst = fromUnknownFun.apply(s);
675 for (List<Type> l = t.lobounds; l.nonEmpty(); l = l.tail) {
676 if (!isSubtype(l.head, t.inst))
677 return false;
678 }
679 for (List<Type> l = t.hibounds; l.nonEmpty(); l = l.tail) {
680 if (!isSubtype(t.inst, l.head))
681 return false;
682 }
683 return true;
684 }
686 @Override
687 public Boolean visitErrorType(ErrorType t, Type s) {
688 return true;
689 }
690 };
691 // </editor-fold>
693 // <editor-fold defaultstate="collapsed" desc="fromUnknownFun">
694 /**
695 * A mapping that turns all unknown types in this type to fresh
696 * unknown variables.
697 */
698 public Mapping fromUnknownFun = new Mapping("fromUnknownFun") {
699 public Type apply(Type t) {
700 if (t.tag == UNKNOWN) return new UndetVar(t);
701 else return t.map(this);
702 }
703 };
704 // </editor-fold>
706 // <editor-fold defaultstate="collapsed" desc="Contains Type">
707 public boolean containedBy(Type t, Type s) {
708 switch (t.tag) {
709 case UNDETVAR:
710 if (s.tag == WILDCARD) {
711 UndetVar undetvar = (UndetVar)t;
712 undetvar.inst = glb(upperBound(s), undetvar.inst);
713 // We should check instantiated type against any of the
714 // undetvar's lower bounds.
715 for (Type t2 : undetvar.lobounds) {
716 if (!isSubtype(t2, undetvar.inst))
717 return false;
718 }
719 return true;
720 } else {
721 return isSameType(t, s);
722 }
723 case ERROR:
724 return true;
725 default:
726 return containsType(s, t);
727 }
728 }
730 boolean containsType(List<Type> ts, List<Type> ss) {
731 while (ts.nonEmpty() && ss.nonEmpty()
732 && containsType(ts.head, ss.head)) {
733 ts = ts.tail;
734 ss = ss.tail;
735 }
736 return ts.isEmpty() && ss.isEmpty();
737 }
739 /**
740 * Check if t contains s.
741 *
742 * <p>T contains S if:
743 *
744 * <p>{@code L(T) <: L(S) && U(S) <: U(T)}
745 *
746 * <p>This relation is only used by ClassType.isSubtype(), that
747 * is,
748 *
749 * <p>{@code C<S> <: C<T> if T contains S.}
750 *
751 * <p>Because of F-bounds, this relation can lead to infinite
752 * recursion. Thus we must somehow break that recursion. Notice
753 * that containsType() is only called from ClassType.isSubtype().
754 * Since the arguments have already been checked against their
755 * bounds, we know:
756 *
757 * <p>{@code U(S) <: U(T) if T is "super" bound (U(T) *is* the bound)}
758 *
759 * <p>{@code L(T) <: L(S) if T is "extends" bound (L(T) is bottom)}
760 *
761 * @param t a type
762 * @param s a type
763 */
764 public boolean containsType(Type t, Type s) {
765 return containsType.visit(t, s);
766 }
767 // where
768 private TypeRelation containsType = new TypeRelation() {
770 private Type U(Type t) {
771 while (t.tag == WILDCARD) {
772 WildcardType w = (WildcardType)t;
773 if (w.isSuperBound())
774 return w.bound == null ? syms.objectType : w.bound.bound;
775 else
776 t = w.type;
777 }
778 return t;
779 }
781 private Type L(Type t) {
782 while (t.tag == WILDCARD) {
783 WildcardType w = (WildcardType)t;
784 if (w.isExtendsBound())
785 return syms.botType;
786 else
787 t = w.type;
788 }
789 return t;
790 }
792 public Boolean visitType(Type t, Type s) {
793 if (s.tag >= firstPartialTag)
794 return containedBy(s, t);
795 else
796 return isSameType(t, s);
797 }
799 void debugContainsType(WildcardType t, Type s) {
800 System.err.println();
801 System.err.format(" does %s contain %s?%n", t, s);
802 System.err.format(" %s U(%s) <: U(%s) %s = %s%n",
803 upperBound(s), s, t, U(t),
804 t.isSuperBound()
805 || isSubtypeNoCapture(upperBound(s), U(t)));
806 System.err.format(" %s L(%s) <: L(%s) %s = %s%n",
807 L(t), t, s, lowerBound(s),
808 t.isExtendsBound()
809 || isSubtypeNoCapture(L(t), lowerBound(s)));
810 System.err.println();
811 }
813 @Override
814 public Boolean visitWildcardType(WildcardType t, Type s) {
815 if (s.tag >= firstPartialTag)
816 return containedBy(s, t);
817 else {
818 // debugContainsType(t, s);
819 return isSameWildcard(t, s)
820 || isCaptureOf(s, t)
821 || ((t.isExtendsBound() || isSubtypeNoCapture(L(t), lowerBound(s))) &&
822 (t.isSuperBound() || isSubtypeNoCapture(upperBound(s), U(t))));
823 }
824 }
826 @Override
827 public Boolean visitUndetVar(UndetVar t, Type s) {
828 if (s.tag != WILDCARD)
829 return isSameType(t, s);
830 else
831 return false;
832 }
834 @Override
835 public Boolean visitErrorType(ErrorType t, Type s) {
836 return true;
837 }
838 };
840 public boolean isCaptureOf(Type s, WildcardType t) {
841 if (s.tag != TYPEVAR || !((TypeVar)s).isCaptured())
842 return false;
843 return isSameWildcard(t, ((CapturedType)s).wildcard);
844 }
846 public boolean isSameWildcard(WildcardType t, Type s) {
847 if (s.tag != WILDCARD)
848 return false;
849 WildcardType w = (WildcardType)s;
850 return w.kind == t.kind && w.type == t.type;
851 }
853 public boolean containsTypeEquivalent(List<Type> ts, List<Type> ss) {
854 while (ts.nonEmpty() && ss.nonEmpty()
855 && containsTypeEquivalent(ts.head, ss.head)) {
856 ts = ts.tail;
857 ss = ss.tail;
858 }
859 return ts.isEmpty() && ss.isEmpty();
860 }
861 // </editor-fold>
863 // <editor-fold defaultstate="collapsed" desc="isCastable">
864 public boolean isCastable(Type t, Type s) {
865 return isCastable(t, s, Warner.noWarnings);
866 }
868 /**
869 * Is t is castable to s?<br>
870 * s is assumed to be an erased type.<br>
871 * (not defined for Method and ForAll types).
872 */
873 public boolean isCastable(Type t, Type s, Warner warn) {
874 if (t == s)
875 return true;
877 if (t.isPrimitive() != s.isPrimitive())
878 return allowBoxing && isConvertible(t, s, warn);
880 if (warn != warnStack.head) {
881 try {
882 warnStack = warnStack.prepend(warn);
883 return isCastable.visit(t,s);
884 } finally {
885 warnStack = warnStack.tail;
886 }
887 } else {
888 return isCastable.visit(t,s);
889 }
890 }
891 // where
892 private TypeRelation isCastable = new TypeRelation() {
894 public Boolean visitType(Type t, Type s) {
895 if (s.tag == ERROR)
896 return true;
898 switch (t.tag) {
899 case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
900 case DOUBLE:
901 return s.tag <= DOUBLE;
902 case BOOLEAN:
903 return s.tag == BOOLEAN;
904 case VOID:
905 return false;
906 case BOT:
907 return isSubtype(t, s);
908 default:
909 throw new AssertionError();
910 }
911 }
913 @Override
914 public Boolean visitWildcardType(WildcardType t, Type s) {
915 return isCastable(upperBound(t), s, warnStack.head);
916 }
918 @Override
919 public Boolean visitClassType(ClassType t, Type s) {
920 if (s.tag == ERROR || s.tag == BOT)
921 return true;
923 if (s.tag == TYPEVAR) {
924 if (isCastable(s.getUpperBound(), t, Warner.noWarnings)) {
925 warnStack.head.warnUnchecked();
926 return true;
927 } else {
928 return false;
929 }
930 }
932 if (t.isCompound()) {
933 if (!visit(supertype(t), s))
934 return false;
935 for (Type intf : interfaces(t)) {
936 if (!visit(intf, s))
937 return false;
938 }
939 return true;
940 }
942 if (s.isCompound()) {
943 // call recursively to reuse the above code
944 return visitClassType((ClassType)s, t);
945 }
947 if (s.tag == CLASS || s.tag == ARRAY) {
948 boolean upcast;
949 if ((upcast = isSubtype(erasure(t), erasure(s)))
950 || isSubtype(erasure(s), erasure(t))) {
951 if (!upcast && s.tag == ARRAY) {
952 if (!isReifiable(s))
953 warnStack.head.warnUnchecked();
954 return true;
955 } else if (s.isRaw()) {
956 return true;
957 } else if (t.isRaw()) {
958 if (!isUnbounded(s))
959 warnStack.head.warnUnchecked();
960 return true;
961 }
962 // Assume |a| <: |b|
963 final Type a = upcast ? t : s;
964 final Type b = upcast ? s : t;
965 final boolean HIGH = true;
966 final boolean LOW = false;
967 final boolean DONT_REWRITE_TYPEVARS = false;
968 Type aHigh = rewriteQuantifiers(a, HIGH, DONT_REWRITE_TYPEVARS);
969 Type aLow = rewriteQuantifiers(a, LOW, DONT_REWRITE_TYPEVARS);
970 Type bHigh = rewriteQuantifiers(b, HIGH, DONT_REWRITE_TYPEVARS);
971 Type bLow = rewriteQuantifiers(b, LOW, DONT_REWRITE_TYPEVARS);
972 Type lowSub = asSub(bLow, aLow.tsym);
973 Type highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
974 if (highSub == null) {
975 final boolean REWRITE_TYPEVARS = true;
976 aHigh = rewriteQuantifiers(a, HIGH, REWRITE_TYPEVARS);
977 aLow = rewriteQuantifiers(a, LOW, REWRITE_TYPEVARS);
978 bHigh = rewriteQuantifiers(b, HIGH, REWRITE_TYPEVARS);
979 bLow = rewriteQuantifiers(b, LOW, REWRITE_TYPEVARS);
980 lowSub = asSub(bLow, aLow.tsym);
981 highSub = (lowSub == null) ? null : asSub(bHigh, aHigh.tsym);
982 }
983 if (highSub != null) {
984 assert a.tsym == highSub.tsym && a.tsym == lowSub.tsym
985 : a.tsym + " != " + highSub.tsym + " != " + lowSub.tsym;
986 if (!disjointTypes(aHigh.allparams(), highSub.allparams())
987 && !disjointTypes(aHigh.allparams(), lowSub.allparams())
988 && !disjointTypes(aLow.allparams(), highSub.allparams())
989 && !disjointTypes(aLow.allparams(), lowSub.allparams())) {
990 if (upcast ? giveWarning(a, highSub) || giveWarning(a, lowSub)
991 : giveWarning(highSub, a) || giveWarning(lowSub, a))
992 warnStack.head.warnUnchecked();
993 return true;
994 }
995 }
996 if (isReifiable(s))
997 return isSubtypeUnchecked(a, b);
998 else
999 return isSubtypeUnchecked(a, b, warnStack.head);
1000 }
1002 // Sidecast
1003 if (s.tag == CLASS) {
1004 if ((s.tsym.flags() & INTERFACE) != 0) {
1005 return ((t.tsym.flags() & FINAL) == 0)
1006 ? sideCast(t, s, warnStack.head)
1007 : sideCastFinal(t, s, warnStack.head);
1008 } else if ((t.tsym.flags() & INTERFACE) != 0) {
1009 return ((s.tsym.flags() & FINAL) == 0)
1010 ? sideCast(t, s, warnStack.head)
1011 : sideCastFinal(t, s, warnStack.head);
1012 } else {
1013 // unrelated class types
1014 return false;
1015 }
1016 }
1017 }
1018 return false;
1019 }
1021 @Override
1022 public Boolean visitArrayType(ArrayType t, Type s) {
1023 switch (s.tag) {
1024 case ERROR:
1025 case BOT:
1026 return true;
1027 case TYPEVAR:
1028 if (isCastable(s, t, Warner.noWarnings)) {
1029 warnStack.head.warnUnchecked();
1030 return true;
1031 } else {
1032 return false;
1033 }
1034 case CLASS:
1035 return isSubtype(t, s);
1036 case ARRAY:
1037 if (elemtype(t).tag <= lastBaseTag) {
1038 return elemtype(t).tag == elemtype(s).tag;
1039 } else {
1040 return visit(elemtype(t), elemtype(s));
1041 }
1042 default:
1043 return false;
1044 }
1045 }
1047 @Override
1048 public Boolean visitTypeVar(TypeVar t, Type s) {
1049 switch (s.tag) {
1050 case ERROR:
1051 case BOT:
1052 return true;
1053 case TYPEVAR:
1054 if (isSubtype(t, s)) {
1055 return true;
1056 } else if (isCastable(t.bound, s, Warner.noWarnings)) {
1057 warnStack.head.warnUnchecked();
1058 return true;
1059 } else {
1060 return false;
1061 }
1062 default:
1063 return isCastable(t.bound, s, warnStack.head);
1064 }
1065 }
1067 @Override
1068 public Boolean visitErrorType(ErrorType t, Type s) {
1069 return true;
1070 }
1071 };
1072 // </editor-fold>
1074 // <editor-fold defaultstate="collapsed" desc="disjointTypes">
1075 public boolean disjointTypes(List<Type> ts, List<Type> ss) {
1076 while (ts.tail != null && ss.tail != null) {
1077 if (disjointType(ts.head, ss.head)) return true;
1078 ts = ts.tail;
1079 ss = ss.tail;
1080 }
1081 return false;
1082 }
1084 /**
1085 * Two types or wildcards are considered disjoint if it can be
1086 * proven that no type can be contained in both. It is
1087 * conservative in that it is allowed to say that two types are
1088 * not disjoint, even though they actually are.
1089 *
1090 * The type C<X> is castable to C<Y> exactly if X and Y are not
1091 * disjoint.
1092 */
1093 public boolean disjointType(Type t, Type s) {
1094 return disjointType.visit(t, s);
1095 }
1096 // where
1097 private TypeRelation disjointType = new TypeRelation() {
1099 private Set<TypePair> cache = new HashSet<TypePair>();
1101 public Boolean visitType(Type t, Type s) {
1102 if (s.tag == WILDCARD)
1103 return visit(s, t);
1104 else
1105 return notSoftSubtypeRecursive(t, s) || notSoftSubtypeRecursive(s, t);
1106 }
1108 private boolean isCastableRecursive(Type t, Type s) {
1109 TypePair pair = new TypePair(t, s);
1110 if (cache.add(pair)) {
1111 try {
1112 return Types.this.isCastable(t, s);
1113 } finally {
1114 cache.remove(pair);
1115 }
1116 } else {
1117 return true;
1118 }
1119 }
1121 private boolean notSoftSubtypeRecursive(Type t, Type s) {
1122 TypePair pair = new TypePair(t, s);
1123 if (cache.add(pair)) {
1124 try {
1125 return Types.this.notSoftSubtype(t, s);
1126 } finally {
1127 cache.remove(pair);
1128 }
1129 } else {
1130 return false;
1131 }
1132 }
1134 @Override
1135 public Boolean visitWildcardType(WildcardType t, Type s) {
1136 if (t.isUnbound())
1137 return false;
1139 if (s.tag != WILDCARD) {
1140 if (t.isExtendsBound())
1141 return notSoftSubtypeRecursive(s, t.type);
1142 else // isSuperBound()
1143 return notSoftSubtypeRecursive(t.type, s);
1144 }
1146 if (s.isUnbound())
1147 return false;
1149 if (t.isExtendsBound()) {
1150 if (s.isExtendsBound())
1151 return !isCastableRecursive(t.type, upperBound(s));
1152 else if (s.isSuperBound())
1153 return notSoftSubtypeRecursive(lowerBound(s), t.type);
1154 } else if (t.isSuperBound()) {
1155 if (s.isExtendsBound())
1156 return notSoftSubtypeRecursive(t.type, upperBound(s));
1157 }
1158 return false;
1159 }
1160 };
1161 // </editor-fold>
1163 // <editor-fold defaultstate="collapsed" desc="lowerBoundArgtypes">
1164 /**
1165 * Returns the lower bounds of the formals of a method.
1166 */
1167 public List<Type> lowerBoundArgtypes(Type t) {
1168 return map(t.getParameterTypes(), lowerBoundMapping);
1169 }
1170 private final Mapping lowerBoundMapping = new Mapping("lowerBound") {
1171 public Type apply(Type t) {
1172 return lowerBound(t);
1173 }
1174 };
1175 // </editor-fold>
1177 // <editor-fold defaultstate="collapsed" desc="notSoftSubtype">
1178 /**
1179 * This relation answers the question: is impossible that
1180 * something of type `t' can be a subtype of `s'? This is
1181 * different from the question "is `t' not a subtype of `s'?"
1182 * when type variables are involved: Integer is not a subtype of T
1183 * where <T extends Number> but it is not true that Integer cannot
1184 * possibly be a subtype of T.
1185 */
1186 public boolean notSoftSubtype(Type t, Type s) {
1187 if (t == s) return false;
1188 if (t.tag == TYPEVAR) {
1189 TypeVar tv = (TypeVar) t;
1190 if (s.tag == TYPEVAR)
1191 s = s.getUpperBound();
1192 return !isCastable(tv.bound,
1193 s,
1194 Warner.noWarnings);
1195 }
1196 if (s.tag != WILDCARD)
1197 s = upperBound(s);
1198 if (s.tag == TYPEVAR)
1199 s = s.getUpperBound();
1201 return !isSubtype(t, s);
1202 }
1203 // </editor-fold>
1205 // <editor-fold defaultstate="collapsed" desc="isReifiable">
1206 public boolean isReifiable(Type t) {
1207 return isReifiable.visit(t);
1208 }
1209 // where
1210 private UnaryVisitor<Boolean> isReifiable = new UnaryVisitor<Boolean>() {
1212 public Boolean visitType(Type t, Void ignored) {
1213 return true;
1214 }
1216 @Override
1217 public Boolean visitClassType(ClassType t, Void ignored) {
1218 if (!t.isParameterized())
1219 return true;
1221 for (Type param : t.allparams()) {
1222 if (!param.isUnbound())
1223 return false;
1224 }
1225 return true;
1226 }
1228 @Override
1229 public Boolean visitArrayType(ArrayType t, Void ignored) {
1230 return visit(t.elemtype);
1231 }
1233 @Override
1234 public Boolean visitTypeVar(TypeVar t, Void ignored) {
1235 return false;
1236 }
1237 };
1238 // </editor-fold>
1240 // <editor-fold defaultstate="collapsed" desc="Array Utils">
1241 public boolean isArray(Type t) {
1242 while (t.tag == WILDCARD)
1243 t = upperBound(t);
1244 return t.tag == ARRAY;
1245 }
1247 /**
1248 * The element type of an array.
1249 */
1250 public Type elemtype(Type t) {
1251 switch (t.tag) {
1252 case WILDCARD:
1253 return elemtype(upperBound(t));
1254 case ARRAY:
1255 return ((ArrayType)t).elemtype;
1256 case FORALL:
1257 return elemtype(((ForAll)t).qtype);
1258 case ERROR:
1259 return t;
1260 default:
1261 return null;
1262 }
1263 }
1265 /**
1266 * Mapping to take element type of an arraytype
1267 */
1268 private Mapping elemTypeFun = new Mapping ("elemTypeFun") {
1269 public Type apply(Type t) { return elemtype(t); }
1270 };
1272 /**
1273 * The number of dimensions of an array type.
1274 */
1275 public int dimensions(Type t) {
1276 int result = 0;
1277 while (t.tag == ARRAY) {
1278 result++;
1279 t = elemtype(t);
1280 }
1281 return result;
1282 }
1283 // </editor-fold>
1285 // <editor-fold defaultstate="collapsed" desc="asSuper">
1286 /**
1287 * Return the (most specific) base type of t that starts with the
1288 * given symbol. If none exists, return null.
1289 *
1290 * @param t a type
1291 * @param sym a symbol
1292 */
1293 public Type asSuper(Type t, Symbol sym) {
1294 return asSuper.visit(t, sym);
1295 }
1296 // where
1297 private SimpleVisitor<Type,Symbol> asSuper = new SimpleVisitor<Type,Symbol>() {
1299 public Type visitType(Type t, Symbol sym) {
1300 return null;
1301 }
1303 @Override
1304 public Type visitClassType(ClassType t, Symbol sym) {
1305 if (t.tsym == sym)
1306 return t;
1308 Type st = supertype(t);
1309 if (st.tag == CLASS || st.tag == TYPEVAR || st.tag == ERROR) {
1310 Type x = asSuper(st, sym);
1311 if (x != null)
1312 return x;
1313 }
1314 if ((sym.flags() & INTERFACE) != 0) {
1315 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
1316 Type x = asSuper(l.head, sym);
1317 if (x != null)
1318 return x;
1319 }
1320 }
1321 return null;
1322 }
1324 @Override
1325 public Type visitArrayType(ArrayType t, Symbol sym) {
1326 return isSubtype(t, sym.type) ? sym.type : null;
1327 }
1329 @Override
1330 public Type visitTypeVar(TypeVar t, Symbol sym) {
1331 if (t.tsym == sym)
1332 return t;
1333 else
1334 return asSuper(t.bound, sym);
1335 }
1337 @Override
1338 public Type visitErrorType(ErrorType t, Symbol sym) {
1339 return t;
1340 }
1341 };
1343 /**
1344 * Return the base type of t or any of its outer types that starts
1345 * with the given symbol. If none exists, return null.
1346 *
1347 * @param t a type
1348 * @param sym a symbol
1349 */
1350 public Type asOuterSuper(Type t, Symbol sym) {
1351 switch (t.tag) {
1352 case CLASS:
1353 do {
1354 Type s = asSuper(t, sym);
1355 if (s != null) return s;
1356 t = t.getEnclosingType();
1357 } while (t.tag == CLASS);
1358 return null;
1359 case ARRAY:
1360 return isSubtype(t, sym.type) ? sym.type : null;
1361 case TYPEVAR:
1362 return asSuper(t, sym);
1363 case ERROR:
1364 return t;
1365 default:
1366 return null;
1367 }
1368 }
1370 /**
1371 * Return the base type of t or any of its enclosing types that
1372 * starts with the given symbol. If none exists, return null.
1373 *
1374 * @param t a type
1375 * @param sym a symbol
1376 */
1377 public Type asEnclosingSuper(Type t, Symbol sym) {
1378 switch (t.tag) {
1379 case CLASS:
1380 do {
1381 Type s = asSuper(t, sym);
1382 if (s != null) return s;
1383 Type outer = t.getEnclosingType();
1384 t = (outer.tag == CLASS) ? outer :
1385 (t.tsym.owner.enclClass() != null) ? t.tsym.owner.enclClass().type :
1386 Type.noType;
1387 } while (t.tag == CLASS);
1388 return null;
1389 case ARRAY:
1390 return isSubtype(t, sym.type) ? sym.type : null;
1391 case TYPEVAR:
1392 return asSuper(t, sym);
1393 case ERROR:
1394 return t;
1395 default:
1396 return null;
1397 }
1398 }
1399 // </editor-fold>
1401 // <editor-fold defaultstate="collapsed" desc="memberType">
1402 /**
1403 * The type of given symbol, seen as a member of t.
1404 *
1405 * @param t a type
1406 * @param sym a symbol
1407 */
1408 public Type memberType(Type t, Symbol sym) {
1409 return (sym.flags() & STATIC) != 0
1410 ? sym.type
1411 : memberType.visit(t, sym);
1412 }
1413 // where
1414 private SimpleVisitor<Type,Symbol> memberType = new SimpleVisitor<Type,Symbol>() {
1416 public Type visitType(Type t, Symbol sym) {
1417 return sym.type;
1418 }
1420 @Override
1421 public Type visitWildcardType(WildcardType t, Symbol sym) {
1422 return memberType(upperBound(t), sym);
1423 }
1425 @Override
1426 public Type visitClassType(ClassType t, Symbol sym) {
1427 Symbol owner = sym.owner;
1428 long flags = sym.flags();
1429 if (((flags & STATIC) == 0) && owner.type.isParameterized()) {
1430 Type base = asOuterSuper(t, owner);
1431 //if t is an intersection type T = CT & I1 & I2 ... & In
1432 //its supertypes CT, I1, ... In might contain wildcards
1433 //so we need to go through capture conversion
1434 base = t.isCompound() ? capture(base) : base;
1435 if (base != null) {
1436 List<Type> ownerParams = owner.type.allparams();
1437 List<Type> baseParams = base.allparams();
1438 if (ownerParams.nonEmpty()) {
1439 if (baseParams.isEmpty()) {
1440 // then base is a raw type
1441 return erasure(sym.type);
1442 } else {
1443 return subst(sym.type, ownerParams, baseParams);
1444 }
1445 }
1446 }
1447 }
1448 return sym.type;
1449 }
1451 @Override
1452 public Type visitTypeVar(TypeVar t, Symbol sym) {
1453 return memberType(t.bound, sym);
1454 }
1456 @Override
1457 public Type visitErrorType(ErrorType t, Symbol sym) {
1458 return t;
1459 }
1460 };
1461 // </editor-fold>
1463 // <editor-fold defaultstate="collapsed" desc="isAssignable">
1464 public boolean isAssignable(Type t, Type s) {
1465 return isAssignable(t, s, Warner.noWarnings);
1466 }
1468 /**
1469 * Is t assignable to s?<br>
1470 * Equivalent to subtype except for constant values and raw
1471 * types.<br>
1472 * (not defined for Method and ForAll types)
1473 */
1474 public boolean isAssignable(Type t, Type s, Warner warn) {
1475 if (t.tag == ERROR)
1476 return true;
1477 if (t.tag <= INT && t.constValue() != null) {
1478 int value = ((Number)t.constValue()).intValue();
1479 switch (s.tag) {
1480 case BYTE:
1481 if (Byte.MIN_VALUE <= value && value <= Byte.MAX_VALUE)
1482 return true;
1483 break;
1484 case CHAR:
1485 if (Character.MIN_VALUE <= value && value <= Character.MAX_VALUE)
1486 return true;
1487 break;
1488 case SHORT:
1489 if (Short.MIN_VALUE <= value && value <= Short.MAX_VALUE)
1490 return true;
1491 break;
1492 case INT:
1493 return true;
1494 case CLASS:
1495 switch (unboxedType(s).tag) {
1496 case BYTE:
1497 case CHAR:
1498 case SHORT:
1499 return isAssignable(t, unboxedType(s), warn);
1500 }
1501 break;
1502 }
1503 }
1504 return isConvertible(t, s, warn);
1505 }
1506 // </editor-fold>
1508 // <editor-fold defaultstate="collapsed" desc="erasure">
1509 /**
1510 * The erasure of t {@code |t|} -- the type that results when all
1511 * type parameters in t are deleted.
1512 */
1513 public Type erasure(Type t) {
1514 return erasure(t, false);
1515 }
1516 //where
1517 private Type erasure(Type t, boolean recurse) {
1518 if (t.tag <= lastBaseTag)
1519 return t; /* fast special case */
1520 else
1521 return erasure.visit(t, recurse);
1522 }
1523 // where
1524 private SimpleVisitor<Type, Boolean> erasure = new SimpleVisitor<Type, Boolean>() {
1525 public Type visitType(Type t, Boolean recurse) {
1526 if (t.tag <= lastBaseTag)
1527 return t; /*fast special case*/
1528 else
1529 return t.map(recurse ? erasureRecFun : erasureFun);
1530 }
1532 @Override
1533 public Type visitWildcardType(WildcardType t, Boolean recurse) {
1534 return erasure(upperBound(t), recurse);
1535 }
1537 @Override
1538 public Type visitClassType(ClassType t, Boolean recurse) {
1539 Type erased = t.tsym.erasure(Types.this);
1540 if (recurse) {
1541 erased = new ErasedClassType(erased.getEnclosingType(),erased.tsym);
1542 }
1543 return erased;
1544 }
1546 @Override
1547 public Type visitTypeVar(TypeVar t, Boolean recurse) {
1548 return erasure(t.bound, recurse);
1549 }
1551 @Override
1552 public Type visitErrorType(ErrorType t, Boolean recurse) {
1553 return t;
1554 }
1555 };
1557 private Mapping erasureFun = new Mapping ("erasure") {
1558 public Type apply(Type t) { return erasure(t); }
1559 };
1561 private Mapping erasureRecFun = new Mapping ("erasureRecursive") {
1562 public Type apply(Type t) { return erasureRecursive(t); }
1563 };
1565 public List<Type> erasure(List<Type> ts) {
1566 return Type.map(ts, erasureFun);
1567 }
1569 public Type erasureRecursive(Type t) {
1570 return erasure(t, true);
1571 }
1573 public List<Type> erasureRecursive(List<Type> ts) {
1574 return Type.map(ts, erasureRecFun);
1575 }
1576 // </editor-fold>
1578 // <editor-fold defaultstate="collapsed" desc="makeCompoundType">
1579 /**
1580 * Make a compound type from non-empty list of types
1581 *
1582 * @param bounds the types from which the compound type is formed
1583 * @param supertype is objectType if all bounds are interfaces,
1584 * null otherwise.
1585 */
1586 public Type makeCompoundType(List<Type> bounds,
1587 Type supertype) {
1588 ClassSymbol bc =
1589 new ClassSymbol(ABSTRACT|PUBLIC|SYNTHETIC|COMPOUND|ACYCLIC,
1590 Type.moreInfo
1591 ? names.fromString(bounds.toString())
1592 : names.empty,
1593 syms.noSymbol);
1594 if (bounds.head.tag == TYPEVAR)
1595 // error condition, recover
1596 bc.erasure_field = syms.objectType;
1597 else
1598 bc.erasure_field = erasure(bounds.head);
1599 bc.members_field = new Scope(bc);
1600 ClassType bt = (ClassType)bc.type;
1601 bt.allparams_field = List.nil();
1602 if (supertype != null) {
1603 bt.supertype_field = supertype;
1604 bt.interfaces_field = bounds;
1605 } else {
1606 bt.supertype_field = bounds.head;
1607 bt.interfaces_field = bounds.tail;
1608 }
1609 assert bt.supertype_field.tsym.completer != null
1610 || !bt.supertype_field.isInterface()
1611 : bt.supertype_field;
1612 return bt;
1613 }
1615 /**
1616 * Same as {@link #makeCompoundType(List,Type)}, except that the
1617 * second parameter is computed directly. Note that this might
1618 * cause a symbol completion. Hence, this version of
1619 * makeCompoundType may not be called during a classfile read.
1620 */
1621 public Type makeCompoundType(List<Type> bounds) {
1622 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1623 supertype(bounds.head) : null;
1624 return makeCompoundType(bounds, supertype);
1625 }
1627 /**
1628 * A convenience wrapper for {@link #makeCompoundType(List)}; the
1629 * arguments are converted to a list and passed to the other
1630 * method. Note that this might cause a symbol completion.
1631 * Hence, this version of makeCompoundType may not be called
1632 * during a classfile read.
1633 */
1634 public Type makeCompoundType(Type bound1, Type bound2) {
1635 return makeCompoundType(List.of(bound1, bound2));
1636 }
1637 // </editor-fold>
1639 // <editor-fold defaultstate="collapsed" desc="supertype">
1640 public Type supertype(Type t) {
1641 return supertype.visit(t);
1642 }
1643 // where
1644 private UnaryVisitor<Type> supertype = new UnaryVisitor<Type>() {
1646 public Type visitType(Type t, Void ignored) {
1647 // A note on wildcards: there is no good way to
1648 // determine a supertype for a super bounded wildcard.
1649 return null;
1650 }
1652 @Override
1653 public Type visitClassType(ClassType t, Void ignored) {
1654 if (t.supertype_field == null) {
1655 Type supertype = ((ClassSymbol)t.tsym).getSuperclass();
1656 // An interface has no superclass; its supertype is Object.
1657 if (t.isInterface())
1658 supertype = ((ClassType)t.tsym.type).supertype_field;
1659 if (t.supertype_field == null) {
1660 List<Type> actuals = classBound(t).allparams();
1661 List<Type> formals = t.tsym.type.allparams();
1662 if (t.hasErasedSupertypes()) {
1663 t.supertype_field = erasureRecursive(supertype);
1664 } else if (formals.nonEmpty()) {
1665 t.supertype_field = subst(supertype, formals, actuals);
1666 }
1667 else {
1668 t.supertype_field = supertype;
1669 }
1670 }
1671 }
1672 return t.supertype_field;
1673 }
1675 /**
1676 * The supertype is always a class type. If the type
1677 * variable's bounds start with a class type, this is also
1678 * the supertype. Otherwise, the supertype is
1679 * java.lang.Object.
1680 */
1681 @Override
1682 public Type visitTypeVar(TypeVar t, Void ignored) {
1683 if (t.bound.tag == TYPEVAR ||
1684 (!t.bound.isCompound() && !t.bound.isInterface())) {
1685 return t.bound;
1686 } else {
1687 return supertype(t.bound);
1688 }
1689 }
1691 @Override
1692 public Type visitArrayType(ArrayType t, Void ignored) {
1693 if (t.elemtype.isPrimitive() || isSameType(t.elemtype, syms.objectType))
1694 return arraySuperType();
1695 else
1696 return new ArrayType(supertype(t.elemtype), t.tsym);
1697 }
1699 @Override
1700 public Type visitErrorType(ErrorType t, Void ignored) {
1701 return t;
1702 }
1703 };
1704 // </editor-fold>
1706 // <editor-fold defaultstate="collapsed" desc="interfaces">
1707 /**
1708 * Return the interfaces implemented by this class.
1709 */
1710 public List<Type> interfaces(Type t) {
1711 return interfaces.visit(t);
1712 }
1713 // where
1714 private UnaryVisitor<List<Type>> interfaces = new UnaryVisitor<List<Type>>() {
1716 public List<Type> visitType(Type t, Void ignored) {
1717 return List.nil();
1718 }
1720 @Override
1721 public List<Type> visitClassType(ClassType t, Void ignored) {
1722 if (t.interfaces_field == null) {
1723 List<Type> interfaces = ((ClassSymbol)t.tsym).getInterfaces();
1724 if (t.interfaces_field == null) {
1725 // If t.interfaces_field is null, then t must
1726 // be a parameterized type (not to be confused
1727 // with a generic type declaration).
1728 // Terminology:
1729 // Parameterized type: List<String>
1730 // Generic type declaration: class List<E> { ... }
1731 // So t corresponds to List<String> and
1732 // t.tsym.type corresponds to List<E>.
1733 // The reason t must be parameterized type is
1734 // that completion will happen as a side
1735 // effect of calling
1736 // ClassSymbol.getInterfaces. Since
1737 // t.interfaces_field is null after
1738 // completion, we can assume that t is not the
1739 // type of a class/interface declaration.
1740 assert t != t.tsym.type : t.toString();
1741 List<Type> actuals = t.allparams();
1742 List<Type> formals = t.tsym.type.allparams();
1743 if (t.hasErasedSupertypes()) {
1744 t.interfaces_field = erasureRecursive(interfaces);
1745 } else if (formals.nonEmpty()) {
1746 t.interfaces_field =
1747 upperBounds(subst(interfaces, formals, actuals));
1748 }
1749 else {
1750 t.interfaces_field = interfaces;
1751 }
1752 }
1753 }
1754 return t.interfaces_field;
1755 }
1757 @Override
1758 public List<Type> visitTypeVar(TypeVar t, Void ignored) {
1759 if (t.bound.isCompound())
1760 return interfaces(t.bound);
1762 if (t.bound.isInterface())
1763 return List.of(t.bound);
1765 return List.nil();
1766 }
1767 };
1768 // </editor-fold>
1770 // <editor-fold defaultstate="collapsed" desc="isDerivedRaw">
1771 Map<Type,Boolean> isDerivedRawCache = new HashMap<Type,Boolean>();
1773 public boolean isDerivedRaw(Type t) {
1774 Boolean result = isDerivedRawCache.get(t);
1775 if (result == null) {
1776 result = isDerivedRawInternal(t);
1777 isDerivedRawCache.put(t, result);
1778 }
1779 return result;
1780 }
1782 public boolean isDerivedRawInternal(Type t) {
1783 if (t.isErroneous())
1784 return false;
1785 return
1786 t.isRaw() ||
1787 supertype(t) != null && isDerivedRaw(supertype(t)) ||
1788 isDerivedRaw(interfaces(t));
1789 }
1791 public boolean isDerivedRaw(List<Type> ts) {
1792 List<Type> l = ts;
1793 while (l.nonEmpty() && !isDerivedRaw(l.head)) l = l.tail;
1794 return l.nonEmpty();
1795 }
1796 // </editor-fold>
1798 // <editor-fold defaultstate="collapsed" desc="setBounds">
1799 /**
1800 * Set the bounds field of the given type variable to reflect a
1801 * (possibly multiple) list of bounds.
1802 * @param t a type variable
1803 * @param bounds the bounds, must be nonempty
1804 * @param supertype is objectType if all bounds are interfaces,
1805 * null otherwise.
1806 */
1807 public void setBounds(TypeVar t, List<Type> bounds, Type supertype) {
1808 if (bounds.tail.isEmpty())
1809 t.bound = bounds.head;
1810 else
1811 t.bound = makeCompoundType(bounds, supertype);
1812 t.rank_field = -1;
1813 }
1815 /**
1816 * Same as {@link #setBounds(Type.TypeVar,List,Type)}, except that
1817 * third parameter is computed directly. Note that this test
1818 * might cause a symbol completion. Hence, this version of
1819 * setBounds may not be called during a classfile read.
1820 */
1821 public void setBounds(TypeVar t, List<Type> bounds) {
1822 Type supertype = (bounds.head.tsym.flags() & INTERFACE) != 0 ?
1823 supertype(bounds.head) : null;
1824 setBounds(t, bounds, supertype);
1825 t.rank_field = -1;
1826 }
1827 // </editor-fold>
1829 // <editor-fold defaultstate="collapsed" desc="getBounds">
1830 /**
1831 * Return list of bounds of the given type variable.
1832 */
1833 public List<Type> getBounds(TypeVar t) {
1834 if (t.bound.isErroneous() || !t.bound.isCompound())
1835 return List.of(t.bound);
1836 else if ((erasure(t).tsym.flags() & INTERFACE) == 0)
1837 return interfaces(t).prepend(supertype(t));
1838 else
1839 // No superclass was given in bounds.
1840 // In this case, supertype is Object, erasure is first interface.
1841 return interfaces(t);
1842 }
1843 // </editor-fold>
1845 // <editor-fold defaultstate="collapsed" desc="classBound">
1846 /**
1847 * If the given type is a (possibly selected) type variable,
1848 * return the bounding class of this type, otherwise return the
1849 * type itself.
1850 */
1851 public Type classBound(Type t) {
1852 return classBound.visit(t);
1853 }
1854 // where
1855 private UnaryVisitor<Type> classBound = new UnaryVisitor<Type>() {
1857 public Type visitType(Type t, Void ignored) {
1858 return t;
1859 }
1861 @Override
1862 public Type visitClassType(ClassType t, Void ignored) {
1863 Type outer1 = classBound(t.getEnclosingType());
1864 if (outer1 != t.getEnclosingType())
1865 return new ClassType(outer1, t.getTypeArguments(), t.tsym);
1866 else
1867 return t;
1868 }
1870 @Override
1871 public Type visitTypeVar(TypeVar t, Void ignored) {
1872 return classBound(supertype(t));
1873 }
1875 @Override
1876 public Type visitErrorType(ErrorType t, Void ignored) {
1877 return t;
1878 }
1879 };
1880 // </editor-fold>
1882 // <editor-fold defaultstate="collapsed" desc="sub signature / override equivalence">
1883 /**
1884 * Returns true iff the first signature is a <em>sub
1885 * signature</em> of the other. This is <b>not</b> an equivalence
1886 * relation.
1887 *
1888 * @see "The Java Language Specification, Third Ed. (8.4.2)."
1889 * @see #overrideEquivalent(Type t, Type s)
1890 * @param t first signature (possibly raw).
1891 * @param s second signature (could be subjected to erasure).
1892 * @return true if t is a sub signature of s.
1893 */
1894 public boolean isSubSignature(Type t, Type s) {
1895 return hasSameArgs(t, s) || hasSameArgs(t, erasure(s));
1896 }
1898 /**
1899 * Returns true iff these signatures are related by <em>override
1900 * equivalence</em>. This is the natural extension of
1901 * isSubSignature to an equivalence relation.
1902 *
1903 * @see "The Java Language Specification, Third Ed. (8.4.2)."
1904 * @see #isSubSignature(Type t, Type s)
1905 * @param t a signature (possible raw, could be subjected to
1906 * erasure).
1907 * @param s a signature (possible raw, could be subjected to
1908 * erasure).
1909 * @return true if either argument is a sub signature of the other.
1910 */
1911 public boolean overrideEquivalent(Type t, Type s) {
1912 return hasSameArgs(t, s) ||
1913 hasSameArgs(t, erasure(s)) || hasSameArgs(erasure(t), s);
1914 }
1916 /**
1917 * Does t have the same arguments as s? It is assumed that both
1918 * types are (possibly polymorphic) method types. Monomorphic
1919 * method types "have the same arguments", if their argument lists
1920 * are equal. Polymorphic method types "have the same arguments",
1921 * if they have the same arguments after renaming all type
1922 * variables of one to corresponding type variables in the other,
1923 * where correspondence is by position in the type parameter list.
1924 */
1925 public boolean hasSameArgs(Type t, Type s) {
1926 return hasSameArgs.visit(t, s);
1927 }
1928 // where
1929 private TypeRelation hasSameArgs = new TypeRelation() {
1931 public Boolean visitType(Type t, Type s) {
1932 throw new AssertionError();
1933 }
1935 @Override
1936 public Boolean visitMethodType(MethodType t, Type s) {
1937 return s.tag == METHOD
1938 && containsTypeEquivalent(t.argtypes, s.getParameterTypes());
1939 }
1941 @Override
1942 public Boolean visitForAll(ForAll t, Type s) {
1943 if (s.tag != FORALL)
1944 return false;
1946 ForAll forAll = (ForAll)s;
1947 return hasSameBounds(t, forAll)
1948 && visit(t.qtype, subst(forAll.qtype, forAll.tvars, t.tvars));
1949 }
1951 @Override
1952 public Boolean visitErrorType(ErrorType t, Type s) {
1953 return false;
1954 }
1955 };
1956 // </editor-fold>
1958 // <editor-fold defaultstate="collapsed" desc="subst">
1959 public List<Type> subst(List<Type> ts,
1960 List<Type> from,
1961 List<Type> to) {
1962 return new Subst(from, to).subst(ts);
1963 }
1965 /**
1966 * Substitute all occurrences of a type in `from' with the
1967 * corresponding type in `to' in 't'. Match lists `from' and `to'
1968 * from the right: If lists have different length, discard leading
1969 * elements of the longer list.
1970 */
1971 public Type subst(Type t, List<Type> from, List<Type> to) {
1972 return new Subst(from, to).subst(t);
1973 }
1975 private class Subst extends UnaryVisitor<Type> {
1976 List<Type> from;
1977 List<Type> to;
1979 public Subst(List<Type> from, List<Type> to) {
1980 int fromLength = from.length();
1981 int toLength = to.length();
1982 while (fromLength > toLength) {
1983 fromLength--;
1984 from = from.tail;
1985 }
1986 while (fromLength < toLength) {
1987 toLength--;
1988 to = to.tail;
1989 }
1990 this.from = from;
1991 this.to = to;
1992 }
1994 Type subst(Type t) {
1995 if (from.tail == null)
1996 return t;
1997 else
1998 return visit(t);
1999 }
2001 List<Type> subst(List<Type> ts) {
2002 if (from.tail == null)
2003 return ts;
2004 boolean wild = false;
2005 if (ts.nonEmpty() && from.nonEmpty()) {
2006 Type head1 = subst(ts.head);
2007 List<Type> tail1 = subst(ts.tail);
2008 if (head1 != ts.head || tail1 != ts.tail)
2009 return tail1.prepend(head1);
2010 }
2011 return ts;
2012 }
2014 public Type visitType(Type t, Void ignored) {
2015 return t;
2016 }
2018 @Override
2019 public Type visitMethodType(MethodType t, Void ignored) {
2020 List<Type> argtypes = subst(t.argtypes);
2021 Type restype = subst(t.restype);
2022 List<Type> thrown = subst(t.thrown);
2023 if (argtypes == t.argtypes &&
2024 restype == t.restype &&
2025 thrown == t.thrown)
2026 return t;
2027 else
2028 return new MethodType(argtypes, restype, thrown, t.tsym);
2029 }
2031 @Override
2032 public Type visitTypeVar(TypeVar t, Void ignored) {
2033 for (List<Type> from = this.from, to = this.to;
2034 from.nonEmpty();
2035 from = from.tail, to = to.tail) {
2036 if (t == from.head) {
2037 return to.head.withTypeVar(t);
2038 }
2039 }
2040 return t;
2041 }
2043 @Override
2044 public Type visitClassType(ClassType t, Void ignored) {
2045 if (!t.isCompound()) {
2046 List<Type> typarams = t.getTypeArguments();
2047 List<Type> typarams1 = subst(typarams);
2048 Type outer = t.getEnclosingType();
2049 Type outer1 = subst(outer);
2050 if (typarams1 == typarams && outer1 == outer)
2051 return t;
2052 else
2053 return new ClassType(outer1, typarams1, t.tsym);
2054 } else {
2055 Type st = subst(supertype(t));
2056 List<Type> is = upperBounds(subst(interfaces(t)));
2057 if (st == supertype(t) && is == interfaces(t))
2058 return t;
2059 else
2060 return makeCompoundType(is.prepend(st));
2061 }
2062 }
2064 @Override
2065 public Type visitWildcardType(WildcardType t, Void ignored) {
2066 Type bound = t.type;
2067 if (t.kind != BoundKind.UNBOUND)
2068 bound = subst(bound);
2069 if (bound == t.type) {
2070 return t;
2071 } else {
2072 if (t.isExtendsBound() && bound.isExtendsBound())
2073 bound = upperBound(bound);
2074 return new WildcardType(bound, t.kind, syms.boundClass, t.bound);
2075 }
2076 }
2078 @Override
2079 public Type visitArrayType(ArrayType t, Void ignored) {
2080 Type elemtype = subst(t.elemtype);
2081 if (elemtype == t.elemtype)
2082 return t;
2083 else
2084 return new ArrayType(upperBound(elemtype), t.tsym);
2085 }
2087 @Override
2088 public Type visitForAll(ForAll t, Void ignored) {
2089 List<Type> tvars1 = substBounds(t.tvars, from, to);
2090 Type qtype1 = subst(t.qtype);
2091 if (tvars1 == t.tvars && qtype1 == t.qtype) {
2092 return t;
2093 } else if (tvars1 == t.tvars) {
2094 return new ForAll(tvars1, qtype1);
2095 } else {
2096 return new ForAll(tvars1, Types.this.subst(qtype1, t.tvars, tvars1));
2097 }
2098 }
2100 @Override
2101 public Type visitErrorType(ErrorType t, Void ignored) {
2102 return t;
2103 }
2104 }
2106 public List<Type> substBounds(List<Type> tvars,
2107 List<Type> from,
2108 List<Type> to) {
2109 if (tvars.isEmpty())
2110 return tvars;
2111 if (tvars.tail.isEmpty())
2112 // fast common case
2113 return List.<Type>of(substBound((TypeVar)tvars.head, from, to));
2114 ListBuffer<Type> newBoundsBuf = lb();
2115 boolean changed = false;
2116 // calculate new bounds
2117 for (Type t : tvars) {
2118 TypeVar tv = (TypeVar) t;
2119 Type bound = subst(tv.bound, from, to);
2120 if (bound != tv.bound)
2121 changed = true;
2122 newBoundsBuf.append(bound);
2123 }
2124 if (!changed)
2125 return tvars;
2126 ListBuffer<Type> newTvars = lb();
2127 // create new type variables without bounds
2128 for (Type t : tvars) {
2129 newTvars.append(new TypeVar(t.tsym, null, syms.botType));
2130 }
2131 // the new bounds should use the new type variables in place
2132 // of the old
2133 List<Type> newBounds = newBoundsBuf.toList();
2134 from = tvars;
2135 to = newTvars.toList();
2136 for (; !newBounds.isEmpty(); newBounds = newBounds.tail) {
2137 newBounds.head = subst(newBounds.head, from, to);
2138 }
2139 newBounds = newBoundsBuf.toList();
2140 // set the bounds of new type variables to the new bounds
2141 for (Type t : newTvars.toList()) {
2142 TypeVar tv = (TypeVar) t;
2143 tv.bound = newBounds.head;
2144 newBounds = newBounds.tail;
2145 }
2146 return newTvars.toList();
2147 }
2149 public TypeVar substBound(TypeVar t, List<Type> from, List<Type> to) {
2150 Type bound1 = subst(t.bound, from, to);
2151 if (bound1 == t.bound)
2152 return t;
2153 else
2154 return new TypeVar(t.tsym, bound1, syms.botType);
2155 }
2156 // </editor-fold>
2158 // <editor-fold defaultstate="collapsed" desc="hasSameBounds">
2159 /**
2160 * Does t have the same bounds for quantified variables as s?
2161 */
2162 boolean hasSameBounds(ForAll t, ForAll s) {
2163 List<Type> l1 = t.tvars;
2164 List<Type> l2 = s.tvars;
2165 while (l1.nonEmpty() && l2.nonEmpty() &&
2166 isSameType(l1.head.getUpperBound(),
2167 subst(l2.head.getUpperBound(),
2168 s.tvars,
2169 t.tvars))) {
2170 l1 = l1.tail;
2171 l2 = l2.tail;
2172 }
2173 return l1.isEmpty() && l2.isEmpty();
2174 }
2175 // </editor-fold>
2177 // <editor-fold defaultstate="collapsed" desc="newInstances">
2178 /** Create new vector of type variables from list of variables
2179 * changing all recursive bounds from old to new list.
2180 */
2181 public List<Type> newInstances(List<Type> tvars) {
2182 List<Type> tvars1 = Type.map(tvars, newInstanceFun);
2183 for (List<Type> l = tvars1; l.nonEmpty(); l = l.tail) {
2184 TypeVar tv = (TypeVar) l.head;
2185 tv.bound = subst(tv.bound, tvars, tvars1);
2186 }
2187 return tvars1;
2188 }
2189 static private Mapping newInstanceFun = new Mapping("newInstanceFun") {
2190 public Type apply(Type t) { return new TypeVar(t.tsym, t.getUpperBound(), t.getLowerBound()); }
2191 };
2192 // </editor-fold>
2194 // <editor-fold defaultstate="collapsed" desc="createErrorType">
2195 public Type createErrorType(Type originalType) {
2196 return new ErrorType(originalType, syms.errSymbol);
2197 }
2199 public Type createErrorType(ClassSymbol c, Type originalType) {
2200 return new ErrorType(c, originalType);
2201 }
2203 public Type createErrorType(Name name, TypeSymbol container, Type originalType) {
2204 return new ErrorType(name, container, originalType);
2205 }
2206 // </editor-fold>
2208 // <editor-fold defaultstate="collapsed" desc="rank">
2209 /**
2210 * The rank of a class is the length of the longest path between
2211 * the class and java.lang.Object in the class inheritance
2212 * graph. Undefined for all but reference types.
2213 */
2214 public int rank(Type t) {
2215 switch(t.tag) {
2216 case CLASS: {
2217 ClassType cls = (ClassType)t;
2218 if (cls.rank_field < 0) {
2219 Name fullname = cls.tsym.getQualifiedName();
2220 if (fullname == names.java_lang_Object)
2221 cls.rank_field = 0;
2222 else {
2223 int r = rank(supertype(cls));
2224 for (List<Type> l = interfaces(cls);
2225 l.nonEmpty();
2226 l = l.tail) {
2227 if (rank(l.head) > r)
2228 r = rank(l.head);
2229 }
2230 cls.rank_field = r + 1;
2231 }
2232 }
2233 return cls.rank_field;
2234 }
2235 case TYPEVAR: {
2236 TypeVar tvar = (TypeVar)t;
2237 if (tvar.rank_field < 0) {
2238 int r = rank(supertype(tvar));
2239 for (List<Type> l = interfaces(tvar);
2240 l.nonEmpty();
2241 l = l.tail) {
2242 if (rank(l.head) > r) r = rank(l.head);
2243 }
2244 tvar.rank_field = r + 1;
2245 }
2246 return tvar.rank_field;
2247 }
2248 case ERROR:
2249 return 0;
2250 default:
2251 throw new AssertionError();
2252 }
2253 }
2254 // </editor-fold>
2256 // <editor-fold defaultstate="collapsed" desc="printType">
2257 /**
2258 * Visitor for generating a string representation of a given type
2259 * accordingly to a given locale
2260 */
2261 public String toString(Type t, Locale locale) {
2262 return typePrinter.visit(t, locale);
2263 }
2264 // where
2265 private TypePrinter typePrinter = new TypePrinter();
2267 public class TypePrinter extends DefaultTypeVisitor<String, Locale> {
2269 public String visit(List<Type> ts, Locale locale) {
2270 ListBuffer<String> sbuf = lb();
2271 for (Type t : ts) {
2272 sbuf.append(visit(t, locale));
2273 }
2274 return sbuf.toList().toString();
2275 }
2277 @Override
2278 public String visitCapturedType(CapturedType t, Locale locale) {
2279 return messages.getLocalizedString("compiler.misc.type.captureof",
2280 (t.hashCode() & 0xFFFFFFFFL) % Type.CapturedType.PRIME,
2281 visit(t.wildcard, locale));
2282 }
2284 @Override
2285 public String visitForAll(ForAll t, Locale locale) {
2286 return "<" + visit(t.tvars, locale) + ">" + visit(t.qtype, locale);
2287 }
2289 @Override
2290 public String visitUndetVar(UndetVar t, Locale locale) {
2291 if (t.inst != null) {
2292 return visit(t.inst, locale);
2293 } else {
2294 return visit(t.qtype, locale) + "?";
2295 }
2296 }
2298 @Override
2299 public String visitArrayType(ArrayType t, Locale locale) {
2300 return visit(t.elemtype, locale) + "[]";
2301 }
2303 @Override
2304 public String visitClassType(ClassType t, Locale locale) {
2305 StringBuffer buf = new StringBuffer();
2306 if (t.getEnclosingType().tag == CLASS && t.tsym.owner.kind == Kinds.TYP) {
2307 buf.append(visit(t.getEnclosingType(), locale));
2308 buf.append(".");
2309 buf.append(className(t, false, locale));
2310 } else {
2311 buf.append(className(t, true, locale));
2312 }
2313 if (t.getTypeArguments().nonEmpty()) {
2314 buf.append('<');
2315 buf.append(visit(t.getTypeArguments(), locale));
2316 buf.append(">");
2317 }
2318 return buf.toString();
2319 }
2321 @Override
2322 public String visitMethodType(MethodType t, Locale locale) {
2323 return "(" + printMethodArgs(t.argtypes, false, locale) + ")" + visit(t.restype, locale);
2324 }
2326 @Override
2327 public String visitPackageType(PackageType t, Locale locale) {
2328 return t.tsym.getQualifiedName().toString();
2329 }
2331 @Override
2332 public String visitWildcardType(WildcardType t, Locale locale) {
2333 StringBuffer s = new StringBuffer();
2334 s.append(t.kind);
2335 if (t.kind != UNBOUND) {
2336 s.append(visit(t.type, locale));
2337 }
2338 return s.toString();
2339 }
2342 public String visitType(Type t, Locale locale) {
2343 String s = (t.tsym == null || t.tsym.name == null)
2344 ? messages.getLocalizedString("compiler.misc.type.none")
2345 : t.tsym.name.toString();
2346 return s;
2347 }
2349 protected String className(ClassType t, boolean longform, Locale locale) {
2350 Symbol sym = t.tsym;
2351 if (sym.name.length() == 0 && (sym.flags() & COMPOUND) != 0) {
2352 StringBuffer s = new StringBuffer(visit(supertype(t), locale));
2353 for (List<Type> is = interfaces(t); is.nonEmpty(); is = is.tail) {
2354 s.append("&");
2355 s.append(visit(is.head, locale));
2356 }
2357 return s.toString();
2358 } else if (sym.name.length() == 0) {
2359 String s;
2360 ClassType norm = (ClassType) t.tsym.type;
2361 if (norm == null) {
2362 s = getLocalizedString(locale, "compiler.misc.anonymous.class", (Object) null);
2363 } else if (interfaces(norm).nonEmpty()) {
2364 s = getLocalizedString(locale, "compiler.misc.anonymous.class",
2365 visit(interfaces(norm).head, locale));
2366 } else {
2367 s = getLocalizedString(locale, "compiler.misc.anonymous.class",
2368 visit(supertype(norm), locale));
2369 }
2370 return s;
2371 } else if (longform) {
2372 return sym.getQualifiedName().toString();
2373 } else {
2374 return sym.name.toString();
2375 }
2376 }
2378 protected String printMethodArgs(List<Type> args, boolean varArgs, Locale locale) {
2379 if (!varArgs) {
2380 return visit(args, locale);
2381 } else {
2382 StringBuffer buf = new StringBuffer();
2383 while (args.tail.nonEmpty()) {
2384 buf.append(visit(args.head, locale));
2385 args = args.tail;
2386 buf.append(',');
2387 }
2388 if (args.head.tag == ARRAY) {
2389 buf.append(visit(((ArrayType) args.head).elemtype, locale));
2390 buf.append("...");
2391 } else {
2392 buf.append(visit(args.head, locale));
2393 }
2394 return buf.toString();
2395 }
2396 }
2398 protected String getLocalizedString(Locale locale, String key, Object... args) {
2399 return messages.getLocalizedString(key, args);
2400 }
2401 };
2402 // </editor-fold>
2404 // <editor-fold defaultstate="collapsed" desc="printSymbol">
2405 /**
2406 * Visitor for generating a string representation of a given symbol
2407 * accordingly to a given locale
2408 */
2409 public String toString(Symbol t, Locale locale) {
2410 return symbolPrinter.visit(t, locale);
2411 }
2412 // where
2413 private SymbolPrinter symbolPrinter = new SymbolPrinter();
2415 public class SymbolPrinter extends DefaultSymbolVisitor<String, Locale> {
2417 @Override
2418 public String visitClassSymbol(ClassSymbol sym, Locale locale) {
2419 return sym.name.isEmpty()
2420 ? getLocalizedString(locale, "compiler.misc.anonymous.class", sym.flatname)
2421 : sym.fullname.toString();
2422 }
2424 @Override
2425 public String visitMethodSymbol(MethodSymbol s, Locale locale) {
2426 if ((s.flags() & BLOCK) != 0) {
2427 return s.owner.name.toString();
2428 } else {
2429 String ms = (s.name == names.init)
2430 ? s.owner.name.toString()
2431 : s.name.toString();
2432 if (s.type != null) {
2433 if (s.type.tag == FORALL) {
2434 ms = "<" + typePrinter.visit(s.type.getTypeArguments(), locale) + ">" + ms;
2435 }
2436 ms += "(" + typePrinter.printMethodArgs(
2437 s.type.getParameterTypes(),
2438 (s.flags() & VARARGS) != 0,
2439 locale) + ")";
2440 }
2441 return ms;
2442 }
2443 }
2445 @Override
2446 public String visitOperatorSymbol(OperatorSymbol s, Locale locale) {
2447 return visitMethodSymbol(s, locale);
2448 }
2450 @Override
2451 public String visitPackageSymbol(PackageSymbol s, Locale locale) {
2452 return s.name.isEmpty()
2453 ? getLocalizedString(locale, "compiler.misc.unnamed.package")
2454 : s.fullname.toString();
2455 }
2457 @Override
2458 public String visitSymbol(Symbol s, Locale locale) {
2459 return s.name.toString();
2460 }
2462 public String visit(List<Symbol> ts, Locale locale) {
2463 ListBuffer<String> sbuf = lb();
2464 for (Symbol t : ts) {
2465 sbuf.append(visit(t, locale));
2466 }
2467 return sbuf.toList().toString();
2468 }
2470 protected String getLocalizedString(Locale locale, String key, Object... args) {
2471 return messages.getLocalizedString(key, args);
2472 }
2473 };
2474 // </editor-fold>
2476 // <editor-fold defaultstate="collapsed" desc="toString">
2477 /**
2478 * This toString is slightly more descriptive than the one on Type.
2479 *
2480 * @deprecated Types.toString(Type t, Locale l) provides better support
2481 * for localization
2482 */
2483 @Deprecated
2484 public String toString(Type t) {
2485 if (t.tag == FORALL) {
2486 ForAll forAll = (ForAll)t;
2487 return typaramsString(forAll.tvars) + forAll.qtype;
2488 }
2489 return "" + t;
2490 }
2491 // where
2492 private String typaramsString(List<Type> tvars) {
2493 StringBuffer s = new StringBuffer();
2494 s.append('<');
2495 boolean first = true;
2496 for (Type t : tvars) {
2497 if (!first) s.append(", ");
2498 first = false;
2499 appendTyparamString(((TypeVar)t), s);
2500 }
2501 s.append('>');
2502 return s.toString();
2503 }
2504 private void appendTyparamString(TypeVar t, StringBuffer buf) {
2505 buf.append(t);
2506 if (t.bound == null ||
2507 t.bound.tsym.getQualifiedName() == names.java_lang_Object)
2508 return;
2509 buf.append(" extends "); // Java syntax; no need for i18n
2510 Type bound = t.bound;
2511 if (!bound.isCompound()) {
2512 buf.append(bound);
2513 } else if ((erasure(t).tsym.flags() & INTERFACE) == 0) {
2514 buf.append(supertype(t));
2515 for (Type intf : interfaces(t)) {
2516 buf.append('&');
2517 buf.append(intf);
2518 }
2519 } else {
2520 // No superclass was given in bounds.
2521 // In this case, supertype is Object, erasure is first interface.
2522 boolean first = true;
2523 for (Type intf : interfaces(t)) {
2524 if (!first) buf.append('&');
2525 first = false;
2526 buf.append(intf);
2527 }
2528 }
2529 }
2530 // </editor-fold>
2532 // <editor-fold defaultstate="collapsed" desc="Determining least upper bounds of types">
2533 /**
2534 * A cache for closures.
2535 *
2536 * <p>A closure is a list of all the supertypes and interfaces of
2537 * a class or interface type, ordered by ClassSymbol.precedes
2538 * (that is, subclasses come first, arbitrary but fixed
2539 * otherwise).
2540 */
2541 private Map<Type,List<Type>> closureCache = new HashMap<Type,List<Type>>();
2543 /**
2544 * Returns the closure of a class or interface type.
2545 */
2546 public List<Type> closure(Type t) {
2547 List<Type> cl = closureCache.get(t);
2548 if (cl == null) {
2549 Type st = supertype(t);
2550 if (!t.isCompound()) {
2551 if (st.tag == CLASS) {
2552 cl = insert(closure(st), t);
2553 } else if (st.tag == TYPEVAR) {
2554 cl = closure(st).prepend(t);
2555 } else {
2556 cl = List.of(t);
2557 }
2558 } else {
2559 cl = closure(supertype(t));
2560 }
2561 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail)
2562 cl = union(cl, closure(l.head));
2563 closureCache.put(t, cl);
2564 }
2565 return cl;
2566 }
2568 /**
2569 * Insert a type in a closure
2570 */
2571 public List<Type> insert(List<Type> cl, Type t) {
2572 if (cl.isEmpty() || t.tsym.precedes(cl.head.tsym, this)) {
2573 return cl.prepend(t);
2574 } else if (cl.head.tsym.precedes(t.tsym, this)) {
2575 return insert(cl.tail, t).prepend(cl.head);
2576 } else {
2577 return cl;
2578 }
2579 }
2581 /**
2582 * Form the union of two closures
2583 */
2584 public List<Type> union(List<Type> cl1, List<Type> cl2) {
2585 if (cl1.isEmpty()) {
2586 return cl2;
2587 } else if (cl2.isEmpty()) {
2588 return cl1;
2589 } else if (cl1.head.tsym.precedes(cl2.head.tsym, this)) {
2590 return union(cl1.tail, cl2).prepend(cl1.head);
2591 } else if (cl2.head.tsym.precedes(cl1.head.tsym, this)) {
2592 return union(cl1, cl2.tail).prepend(cl2.head);
2593 } else {
2594 return union(cl1.tail, cl2.tail).prepend(cl1.head);
2595 }
2596 }
2598 /**
2599 * Intersect two closures
2600 */
2601 public List<Type> intersect(List<Type> cl1, List<Type> cl2) {
2602 if (cl1 == cl2)
2603 return cl1;
2604 if (cl1.isEmpty() || cl2.isEmpty())
2605 return List.nil();
2606 if (cl1.head.tsym.precedes(cl2.head.tsym, this))
2607 return intersect(cl1.tail, cl2);
2608 if (cl2.head.tsym.precedes(cl1.head.tsym, this))
2609 return intersect(cl1, cl2.tail);
2610 if (isSameType(cl1.head, cl2.head))
2611 return intersect(cl1.tail, cl2.tail).prepend(cl1.head);
2612 if (cl1.head.tsym == cl2.head.tsym &&
2613 cl1.head.tag == CLASS && cl2.head.tag == CLASS) {
2614 if (cl1.head.isParameterized() && cl2.head.isParameterized()) {
2615 Type merge = merge(cl1.head,cl2.head);
2616 return intersect(cl1.tail, cl2.tail).prepend(merge);
2617 }
2618 if (cl1.head.isRaw() || cl2.head.isRaw())
2619 return intersect(cl1.tail, cl2.tail).prepend(erasure(cl1.head));
2620 }
2621 return intersect(cl1.tail, cl2.tail);
2622 }
2623 // where
2624 class TypePair {
2625 final Type t1;
2626 final Type t2;
2627 TypePair(Type t1, Type t2) {
2628 this.t1 = t1;
2629 this.t2 = t2;
2630 }
2631 @Override
2632 public int hashCode() {
2633 return 127 * Types.this.hashCode(t1) + Types.this.hashCode(t2);
2634 }
2635 @Override
2636 public boolean equals(Object obj) {
2637 if (!(obj instanceof TypePair))
2638 return false;
2639 TypePair typePair = (TypePair)obj;
2640 return isSameType(t1, typePair.t1)
2641 && isSameType(t2, typePair.t2);
2642 }
2643 }
2644 Set<TypePair> mergeCache = new HashSet<TypePair>();
2645 private Type merge(Type c1, Type c2) {
2646 ClassType class1 = (ClassType) c1;
2647 List<Type> act1 = class1.getTypeArguments();
2648 ClassType class2 = (ClassType) c2;
2649 List<Type> act2 = class2.getTypeArguments();
2650 ListBuffer<Type> merged = new ListBuffer<Type>();
2651 List<Type> typarams = class1.tsym.type.getTypeArguments();
2653 while (act1.nonEmpty() && act2.nonEmpty() && typarams.nonEmpty()) {
2654 if (containsType(act1.head, act2.head)) {
2655 merged.append(act1.head);
2656 } else if (containsType(act2.head, act1.head)) {
2657 merged.append(act2.head);
2658 } else {
2659 TypePair pair = new TypePair(c1, c2);
2660 Type m;
2661 if (mergeCache.add(pair)) {
2662 m = new WildcardType(lub(upperBound(act1.head),
2663 upperBound(act2.head)),
2664 BoundKind.EXTENDS,
2665 syms.boundClass);
2666 mergeCache.remove(pair);
2667 } else {
2668 m = new WildcardType(syms.objectType,
2669 BoundKind.UNBOUND,
2670 syms.boundClass);
2671 }
2672 merged.append(m.withTypeVar(typarams.head));
2673 }
2674 act1 = act1.tail;
2675 act2 = act2.tail;
2676 typarams = typarams.tail;
2677 }
2678 assert(act1.isEmpty() && act2.isEmpty() && typarams.isEmpty());
2679 return new ClassType(class1.getEnclosingType(), merged.toList(), class1.tsym);
2680 }
2682 /**
2683 * Return the minimum type of a closure, a compound type if no
2684 * unique minimum exists.
2685 */
2686 private Type compoundMin(List<Type> cl) {
2687 if (cl.isEmpty()) return syms.objectType;
2688 List<Type> compound = closureMin(cl);
2689 if (compound.isEmpty())
2690 return null;
2691 else if (compound.tail.isEmpty())
2692 return compound.head;
2693 else
2694 return makeCompoundType(compound);
2695 }
2697 /**
2698 * Return the minimum types of a closure, suitable for computing
2699 * compoundMin or glb.
2700 */
2701 private List<Type> closureMin(List<Type> cl) {
2702 ListBuffer<Type> classes = lb();
2703 ListBuffer<Type> interfaces = lb();
2704 while (!cl.isEmpty()) {
2705 Type current = cl.head;
2706 if (current.isInterface())
2707 interfaces.append(current);
2708 else
2709 classes.append(current);
2710 ListBuffer<Type> candidates = lb();
2711 for (Type t : cl.tail) {
2712 if (!isSubtypeNoCapture(current, t))
2713 candidates.append(t);
2714 }
2715 cl = candidates.toList();
2716 }
2717 return classes.appendList(interfaces).toList();
2718 }
2720 /**
2721 * Return the least upper bound of pair of types. if the lub does
2722 * not exist return null.
2723 */
2724 public Type lub(Type t1, Type t2) {
2725 return lub(List.of(t1, t2));
2726 }
2728 /**
2729 * Return the least upper bound (lub) of set of types. If the lub
2730 * does not exist return the type of null (bottom).
2731 */
2732 public Type lub(List<Type> ts) {
2733 final int ARRAY_BOUND = 1;
2734 final int CLASS_BOUND = 2;
2735 int boundkind = 0;
2736 for (Type t : ts) {
2737 switch (t.tag) {
2738 case CLASS:
2739 boundkind |= CLASS_BOUND;
2740 break;
2741 case ARRAY:
2742 boundkind |= ARRAY_BOUND;
2743 break;
2744 case TYPEVAR:
2745 do {
2746 t = t.getUpperBound();
2747 } while (t.tag == TYPEVAR);
2748 if (t.tag == ARRAY) {
2749 boundkind |= ARRAY_BOUND;
2750 } else {
2751 boundkind |= CLASS_BOUND;
2752 }
2753 break;
2754 default:
2755 if (t.isPrimitive())
2756 return syms.errType;
2757 }
2758 }
2759 switch (boundkind) {
2760 case 0:
2761 return syms.botType;
2763 case ARRAY_BOUND:
2764 // calculate lub(A[], B[])
2765 List<Type> elements = Type.map(ts, elemTypeFun);
2766 for (Type t : elements) {
2767 if (t.isPrimitive()) {
2768 // if a primitive type is found, then return
2769 // arraySuperType unless all the types are the
2770 // same
2771 Type first = ts.head;
2772 for (Type s : ts.tail) {
2773 if (!isSameType(first, s)) {
2774 // lub(int[], B[]) is Cloneable & Serializable
2775 return arraySuperType();
2776 }
2777 }
2778 // all the array types are the same, return one
2779 // lub(int[], int[]) is int[]
2780 return first;
2781 }
2782 }
2783 // lub(A[], B[]) is lub(A, B)[]
2784 return new ArrayType(lub(elements), syms.arrayClass);
2786 case CLASS_BOUND:
2787 // calculate lub(A, B)
2788 while (ts.head.tag != CLASS && ts.head.tag != TYPEVAR)
2789 ts = ts.tail;
2790 assert !ts.isEmpty();
2791 List<Type> cl = closure(ts.head);
2792 for (Type t : ts.tail) {
2793 if (t.tag == CLASS || t.tag == TYPEVAR)
2794 cl = intersect(cl, closure(t));
2795 }
2796 return compoundMin(cl);
2798 default:
2799 // calculate lub(A, B[])
2800 List<Type> classes = List.of(arraySuperType());
2801 for (Type t : ts) {
2802 if (t.tag != ARRAY) // Filter out any arrays
2803 classes = classes.prepend(t);
2804 }
2805 // lub(A, B[]) is lub(A, arraySuperType)
2806 return lub(classes);
2807 }
2808 }
2809 // where
2810 private Type arraySuperType = null;
2811 private Type arraySuperType() {
2812 // initialized lazily to avoid problems during compiler startup
2813 if (arraySuperType == null) {
2814 synchronized (this) {
2815 if (arraySuperType == null) {
2816 // JLS 10.8: all arrays implement Cloneable and Serializable.
2817 arraySuperType = makeCompoundType(List.of(syms.serializableType,
2818 syms.cloneableType),
2819 syms.objectType);
2820 }
2821 }
2822 }
2823 return arraySuperType;
2824 }
2825 // </editor-fold>
2827 // <editor-fold defaultstate="collapsed" desc="Greatest lower bound">
2828 public Type glb(Type t, Type s) {
2829 if (s == null)
2830 return t;
2831 else if (isSubtypeNoCapture(t, s))
2832 return t;
2833 else if (isSubtypeNoCapture(s, t))
2834 return s;
2836 List<Type> closure = union(closure(t), closure(s));
2837 List<Type> bounds = closureMin(closure);
2839 if (bounds.isEmpty()) { // length == 0
2840 return syms.objectType;
2841 } else if (bounds.tail.isEmpty()) { // length == 1
2842 return bounds.head;
2843 } else { // length > 1
2844 int classCount = 0;
2845 for (Type bound : bounds)
2846 if (!bound.isInterface())
2847 classCount++;
2848 if (classCount > 1)
2849 return createErrorType(t);
2850 }
2851 return makeCompoundType(bounds);
2852 }
2853 // </editor-fold>
2855 // <editor-fold defaultstate="collapsed" desc="hashCode">
2856 /**
2857 * Compute a hash code on a type.
2858 */
2859 public static int hashCode(Type t) {
2860 return hashCode.visit(t);
2861 }
2862 // where
2863 private static final UnaryVisitor<Integer> hashCode = new UnaryVisitor<Integer>() {
2865 public Integer visitType(Type t, Void ignored) {
2866 return t.tag;
2867 }
2869 @Override
2870 public Integer visitClassType(ClassType t, Void ignored) {
2871 int result = visit(t.getEnclosingType());
2872 result *= 127;
2873 result += t.tsym.flatName().hashCode();
2874 for (Type s : t.getTypeArguments()) {
2875 result *= 127;
2876 result += visit(s);
2877 }
2878 return result;
2879 }
2881 @Override
2882 public Integer visitWildcardType(WildcardType t, Void ignored) {
2883 int result = t.kind.hashCode();
2884 if (t.type != null) {
2885 result *= 127;
2886 result += visit(t.type);
2887 }
2888 return result;
2889 }
2891 @Override
2892 public Integer visitArrayType(ArrayType t, Void ignored) {
2893 return visit(t.elemtype) + 12;
2894 }
2896 @Override
2897 public Integer visitTypeVar(TypeVar t, Void ignored) {
2898 return System.identityHashCode(t.tsym);
2899 }
2901 @Override
2902 public Integer visitUndetVar(UndetVar t, Void ignored) {
2903 return System.identityHashCode(t);
2904 }
2906 @Override
2907 public Integer visitErrorType(ErrorType t, Void ignored) {
2908 return 0;
2909 }
2910 };
2911 // </editor-fold>
2913 // <editor-fold defaultstate="collapsed" desc="Return-Type-Substitutable">
2914 /**
2915 * Does t have a result that is a subtype of the result type of s,
2916 * suitable for covariant returns? It is assumed that both types
2917 * are (possibly polymorphic) method types. Monomorphic method
2918 * types are handled in the obvious way. Polymorphic method types
2919 * require renaming all type variables of one to corresponding
2920 * type variables in the other, where correspondence is by
2921 * position in the type parameter list. */
2922 public boolean resultSubtype(Type t, Type s, Warner warner) {
2923 List<Type> tvars = t.getTypeArguments();
2924 List<Type> svars = s.getTypeArguments();
2925 Type tres = t.getReturnType();
2926 Type sres = subst(s.getReturnType(), svars, tvars);
2927 return covariantReturnType(tres, sres, warner);
2928 }
2930 /**
2931 * Return-Type-Substitutable.
2932 * @see <a href="http://java.sun.com/docs/books/jls/">The Java
2933 * Language Specification, Third Ed. (8.4.5)</a>
2934 */
2935 public boolean returnTypeSubstitutable(Type r1, Type r2) {
2936 return returnTypeSubstitutable(r1, r2, Warner.noWarnings);
2937 }
2938 //where
2939 public boolean returnTypeSubstitutable(Type r1, Type r2, Warner warner) {
2940 if (hasSameArgs(r1, r2))
2941 return resultSubtype(r1, r2, warner);
2942 else
2943 return covariantReturnType(r1.getReturnType(),
2944 r2.getReturnType(),
2945 warner);
2946 }
2948 /**
2949 * Is t an appropriate return type in an overrider for a
2950 * method that returns s?
2951 */
2952 public boolean covariantReturnType(Type t, Type s, Warner warner) {
2953 //are return types identical?
2954 if (isSameType(t, s))
2955 return true;
2956 //if t and s are both reference types...
2957 else if(source.allowCovariantReturns() &&
2958 !t.isPrimitive() &&
2959 !s.isPrimitive()) {
2960 //check that t is some unchecked subtype of s
2961 if (isSubtypeUnchecked(t, s, warner))
2962 return true;
2963 //otherwise check that t = |s|
2964 else if (isSameType(t, erasure(s))) {
2965 warner.warnUnchecked();
2966 return true;
2967 }
2968 }
2969 //otherwise t is not return type substitutable for s
2970 return false;
2971 }
2972 // </editor-fold>
2974 // <editor-fold defaultstate="collapsed" desc="Box/unbox support">
2975 /**
2976 * Return the class that boxes the given primitive.
2977 */
2978 public ClassSymbol boxedClass(Type t) {
2979 return reader.enterClass(syms.boxedName[t.tag]);
2980 }
2982 /**
2983 * Return the primitive type corresponding to a boxed type.
2984 */
2985 public Type unboxedType(Type t) {
2986 if (allowBoxing) {
2987 for (int i=0; i<syms.boxedName.length; i++) {
2988 Name box = syms.boxedName[i];
2989 if (box != null &&
2990 asSuper(t, reader.enterClass(box)) != null)
2991 return syms.typeOfTag[i];
2992 }
2993 }
2994 return Type.noType;
2995 }
2996 // </editor-fold>
2998 // <editor-fold defaultstate="collapsed" desc="Capture conversion">
2999 /*
3000 * JLS 3rd Ed. 5.1.10 Capture Conversion:
3001 *
3002 * Let G name a generic type declaration with n formal type
3003 * parameters A1 ... An with corresponding bounds U1 ... Un. There
3004 * exists a capture conversion from G<T1 ... Tn> to G<S1 ... Sn>,
3005 * where, for 1 <= i <= n:
3006 *
3007 * + If Ti is a wildcard type argument (4.5.1) of the form ? then
3008 * Si is a fresh type variable whose upper bound is
3009 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is the null
3010 * type.
3011 *
3012 * + If Ti is a wildcard type argument of the form ? extends Bi,
3013 * then Si is a fresh type variable whose upper bound is
3014 * glb(Bi, Ui[A1 := S1, ..., An := Sn]) and whose lower bound is
3015 * the null type, where glb(V1,... ,Vm) is V1 & ... & Vm. It is
3016 * a compile-time error if for any two classes (not interfaces)
3017 * Vi and Vj,Vi is not a subclass of Vj or vice versa.
3018 *
3019 * + If Ti is a wildcard type argument of the form ? super Bi,
3020 * then Si is a fresh type variable whose upper bound is
3021 * Ui[A1 := S1, ..., An := Sn] and whose lower bound is Bi.
3022 *
3023 * + Otherwise, Si = Ti.
3024 *
3025 * Capture conversion on any type other than a parameterized type
3026 * (4.5) acts as an identity conversion (5.1.1). Capture
3027 * conversions never require a special action at run time and
3028 * therefore never throw an exception at run time.
3029 *
3030 * Capture conversion is not applied recursively.
3031 */
3032 /**
3033 * Capture conversion as specified by JLS 3rd Ed.
3034 */
3035 public Type capture(Type t) {
3036 if (t.tag != CLASS)
3037 return t;
3038 ClassType cls = (ClassType)t;
3039 if (cls.isRaw() || !cls.isParameterized())
3040 return cls;
3042 ClassType G = (ClassType)cls.asElement().asType();
3043 List<Type> A = G.getTypeArguments();
3044 List<Type> T = cls.getTypeArguments();
3045 List<Type> S = freshTypeVariables(T);
3047 List<Type> currentA = A;
3048 List<Type> currentT = T;
3049 List<Type> currentS = S;
3050 boolean captured = false;
3051 while (!currentA.isEmpty() &&
3052 !currentT.isEmpty() &&
3053 !currentS.isEmpty()) {
3054 if (currentS.head != currentT.head) {
3055 captured = true;
3056 WildcardType Ti = (WildcardType)currentT.head;
3057 Type Ui = currentA.head.getUpperBound();
3058 CapturedType Si = (CapturedType)currentS.head;
3059 if (Ui == null)
3060 Ui = syms.objectType;
3061 switch (Ti.kind) {
3062 case UNBOUND:
3063 Si.bound = subst(Ui, A, S);
3064 Si.lower = syms.botType;
3065 break;
3066 case EXTENDS:
3067 Si.bound = glb(Ti.getExtendsBound(), subst(Ui, A, S));
3068 Si.lower = syms.botType;
3069 break;
3070 case SUPER:
3071 Si.bound = subst(Ui, A, S);
3072 Si.lower = Ti.getSuperBound();
3073 break;
3074 }
3075 if (Si.bound == Si.lower)
3076 currentS.head = Si.bound;
3077 }
3078 currentA = currentA.tail;
3079 currentT = currentT.tail;
3080 currentS = currentS.tail;
3081 }
3082 if (!currentA.isEmpty() || !currentT.isEmpty() || !currentS.isEmpty())
3083 return erasure(t); // some "rare" type involved
3085 if (captured)
3086 return new ClassType(cls.getEnclosingType(), S, cls.tsym);
3087 else
3088 return t;
3089 }
3090 // where
3091 private List<Type> freshTypeVariables(List<Type> types) {
3092 ListBuffer<Type> result = lb();
3093 for (Type t : types) {
3094 if (t.tag == WILDCARD) {
3095 Type bound = ((WildcardType)t).getExtendsBound();
3096 if (bound == null)
3097 bound = syms.objectType;
3098 result.append(new CapturedType(capturedName,
3099 syms.noSymbol,
3100 bound,
3101 syms.botType,
3102 (WildcardType)t));
3103 } else {
3104 result.append(t);
3105 }
3106 }
3107 return result.toList();
3108 }
3109 // </editor-fold>
3111 // <editor-fold defaultstate="collapsed" desc="Internal utility methods">
3112 private List<Type> upperBounds(List<Type> ss) {
3113 if (ss.isEmpty()) return ss;
3114 Type head = upperBound(ss.head);
3115 List<Type> tail = upperBounds(ss.tail);
3116 if (head != ss.head || tail != ss.tail)
3117 return tail.prepend(head);
3118 else
3119 return ss;
3120 }
3122 private boolean sideCast(Type from, Type to, Warner warn) {
3123 // We are casting from type $from$ to type $to$, which are
3124 // non-final unrelated types. This method
3125 // tries to reject a cast by transferring type parameters
3126 // from $to$ to $from$ by common superinterfaces.
3127 boolean reverse = false;
3128 Type target = to;
3129 if ((to.tsym.flags() & INTERFACE) == 0) {
3130 assert (from.tsym.flags() & INTERFACE) != 0;
3131 reverse = true;
3132 to = from;
3133 from = target;
3134 }
3135 List<Type> commonSupers = superClosure(to, erasure(from));
3136 boolean giveWarning = commonSupers.isEmpty();
3137 // The arguments to the supers could be unified here to
3138 // get a more accurate analysis
3139 while (commonSupers.nonEmpty()) {
3140 Type t1 = asSuper(from, commonSupers.head.tsym);
3141 Type t2 = commonSupers.head; // same as asSuper(to, commonSupers.head.tsym);
3142 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
3143 return false;
3144 giveWarning = giveWarning || (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2));
3145 commonSupers = commonSupers.tail;
3146 }
3147 if (giveWarning && !isReifiable(reverse ? from : to))
3148 warn.warnUnchecked();
3149 if (!source.allowCovariantReturns())
3150 // reject if there is a common method signature with
3151 // incompatible return types.
3152 chk.checkCompatibleAbstracts(warn.pos(), from, to);
3153 return true;
3154 }
3156 private boolean sideCastFinal(Type from, Type to, Warner warn) {
3157 // We are casting from type $from$ to type $to$, which are
3158 // unrelated types one of which is final and the other of
3159 // which is an interface. This method
3160 // tries to reject a cast by transferring type parameters
3161 // from the final class to the interface.
3162 boolean reverse = false;
3163 Type target = to;
3164 if ((to.tsym.flags() & INTERFACE) == 0) {
3165 assert (from.tsym.flags() & INTERFACE) != 0;
3166 reverse = true;
3167 to = from;
3168 from = target;
3169 }
3170 assert (from.tsym.flags() & FINAL) != 0;
3171 Type t1 = asSuper(from, to.tsym);
3172 if (t1 == null) return false;
3173 Type t2 = to;
3174 if (disjointTypes(t1.getTypeArguments(), t2.getTypeArguments()))
3175 return false;
3176 if (!source.allowCovariantReturns())
3177 // reject if there is a common method signature with
3178 // incompatible return types.
3179 chk.checkCompatibleAbstracts(warn.pos(), from, to);
3180 if (!isReifiable(target) &&
3181 (reverse ? giveWarning(t2, t1) : giveWarning(t1, t2)))
3182 warn.warnUnchecked();
3183 return true;
3184 }
3186 private boolean giveWarning(Type from, Type to) {
3187 // To and from are (possibly different) parameterizations
3188 // of the same class or interface
3189 return to.isParameterized() && !containsType(to.allparams(), from.allparams());
3190 }
3192 private List<Type> superClosure(Type t, Type s) {
3193 List<Type> cl = List.nil();
3194 for (List<Type> l = interfaces(t); l.nonEmpty(); l = l.tail) {
3195 if (isSubtype(s, erasure(l.head))) {
3196 cl = insert(cl, l.head);
3197 } else {
3198 cl = union(cl, superClosure(l.head, s));
3199 }
3200 }
3201 return cl;
3202 }
3204 private boolean containsTypeEquivalent(Type t, Type s) {
3205 return
3206 isSameType(t, s) || // shortcut
3207 containsType(t, s) && containsType(s, t);
3208 }
3210 // <editor-fold defaultstate="collapsed" desc="adapt">
3211 /**
3212 * Adapt a type by computing a substitution which maps a source
3213 * type to a target type.
3214 *
3215 * @param source the source type
3216 * @param target the target type
3217 * @param from the type variables of the computed substitution
3218 * @param to the types of the computed substitution.
3219 */
3220 public void adapt(Type source,
3221 Type target,
3222 ListBuffer<Type> from,
3223 ListBuffer<Type> to) throws AdaptFailure {
3224 new Adapter(from, to).adapt(source, target);
3225 }
3227 class Adapter extends SimpleVisitor<Void, Type> {
3229 ListBuffer<Type> from;
3230 ListBuffer<Type> to;
3231 Map<Symbol,Type> mapping;
3233 Adapter(ListBuffer<Type> from, ListBuffer<Type> to) {
3234 this.from = from;
3235 this.to = to;
3236 mapping = new HashMap<Symbol,Type>();
3237 }
3239 public void adapt(Type source, Type target) throws AdaptFailure {
3240 visit(source, target);
3241 List<Type> fromList = from.toList();
3242 List<Type> toList = to.toList();
3243 while (!fromList.isEmpty()) {
3244 Type val = mapping.get(fromList.head.tsym);
3245 if (toList.head != val)
3246 toList.head = val;
3247 fromList = fromList.tail;
3248 toList = toList.tail;
3249 }
3250 }
3252 @Override
3253 public Void visitClassType(ClassType source, Type target) throws AdaptFailure {
3254 if (target.tag == CLASS)
3255 adaptRecursive(source.allparams(), target.allparams());
3256 return null;
3257 }
3259 @Override
3260 public Void visitArrayType(ArrayType source, Type target) throws AdaptFailure {
3261 if (target.tag == ARRAY)
3262 adaptRecursive(elemtype(source), elemtype(target));
3263 return null;
3264 }
3266 @Override
3267 public Void visitWildcardType(WildcardType source, Type target) throws AdaptFailure {
3268 if (source.isExtendsBound())
3269 adaptRecursive(upperBound(source), upperBound(target));
3270 else if (source.isSuperBound())
3271 adaptRecursive(lowerBound(source), lowerBound(target));
3272 return null;
3273 }
3275 @Override
3276 public Void visitTypeVar(TypeVar source, Type target) throws AdaptFailure {
3277 // Check to see if there is
3278 // already a mapping for $source$, in which case
3279 // the old mapping will be merged with the new
3280 Type val = mapping.get(source.tsym);
3281 if (val != null) {
3282 if (val.isSuperBound() && target.isSuperBound()) {
3283 val = isSubtype(lowerBound(val), lowerBound(target))
3284 ? target : val;
3285 } else if (val.isExtendsBound() && target.isExtendsBound()) {
3286 val = isSubtype(upperBound(val), upperBound(target))
3287 ? val : target;
3288 } else if (!isSameType(val, target)) {
3289 throw new AdaptFailure();
3290 }
3291 } else {
3292 val = target;
3293 from.append(source);
3294 to.append(target);
3295 }
3296 mapping.put(source.tsym, val);
3297 return null;
3298 }
3300 @Override
3301 public Void visitType(Type source, Type target) {
3302 return null;
3303 }
3305 private Set<TypePair> cache = new HashSet<TypePair>();
3307 private void adaptRecursive(Type source, Type target) {
3308 TypePair pair = new TypePair(source, target);
3309 if (cache.add(pair)) {
3310 try {
3311 visit(source, target);
3312 } finally {
3313 cache.remove(pair);
3314 }
3315 }
3316 }
3318 private void adaptRecursive(List<Type> source, List<Type> target) {
3319 if (source.length() == target.length()) {
3320 while (source.nonEmpty()) {
3321 adaptRecursive(source.head, target.head);
3322 source = source.tail;
3323 target = target.tail;
3324 }
3325 }
3326 }
3327 }
3329 public static class AdaptFailure extends RuntimeException {
3330 static final long serialVersionUID = -7490231548272701566L;
3331 }
3333 private void adaptSelf(Type t,
3334 ListBuffer<Type> from,
3335 ListBuffer<Type> to) {
3336 try {
3337 //if (t.tsym.type != t)
3338 adapt(t.tsym.type, t, from, to);
3339 } catch (AdaptFailure ex) {
3340 // Adapt should never fail calculating a mapping from
3341 // t.tsym.type to t as there can be no merge problem.
3342 throw new AssertionError(ex);
3343 }
3344 }
3345 // </editor-fold>
3347 /**
3348 * Rewrite all type variables (universal quantifiers) in the given
3349 * type to wildcards (existential quantifiers). This is used to
3350 * determine if a cast is allowed. For example, if high is true
3351 * and {@code T <: Number}, then {@code List<T>} is rewritten to
3352 * {@code List<? extends Number>}. Since {@code List<Integer> <:
3353 * List<? extends Number>} a {@code List<T>} can be cast to {@code
3354 * List<Integer>} with a warning.
3355 * @param t a type
3356 * @param high if true return an upper bound; otherwise a lower
3357 * bound
3358 * @param rewriteTypeVars only rewrite captured wildcards if false;
3359 * otherwise rewrite all type variables
3360 * @return the type rewritten with wildcards (existential
3361 * quantifiers) only
3362 */
3363 private Type rewriteQuantifiers(Type t, boolean high, boolean rewriteTypeVars) {
3364 return new Rewriter(high, rewriteTypeVars).rewrite(t);
3365 }
3367 class Rewriter extends UnaryVisitor<Type> {
3369 boolean high;
3370 boolean rewriteTypeVars;
3372 Rewriter(boolean high, boolean rewriteTypeVars) {
3373 this.high = high;
3374 this.rewriteTypeVars = rewriteTypeVars;
3375 }
3377 Type rewrite(Type t) {
3378 ListBuffer<Type> from = new ListBuffer<Type>();
3379 ListBuffer<Type> to = new ListBuffer<Type>();
3380 adaptSelf(t, from, to);
3381 ListBuffer<Type> rewritten = new ListBuffer<Type>();
3382 List<Type> formals = from.toList();
3383 boolean changed = false;
3384 for (Type arg : to.toList()) {
3385 Type bound = visit(arg);
3386 if (arg != bound) {
3387 changed = true;
3388 bound = high ? makeExtendsWildcard(bound, (TypeVar)formals.head)
3389 : makeSuperWildcard(bound, (TypeVar)formals.head);
3390 }
3391 rewritten.append(bound);
3392 formals = formals.tail;
3393 }
3394 if (changed)
3395 return subst(t.tsym.type, from.toList(), rewritten.toList());
3396 else
3397 return t;
3398 }
3400 public Type visitType(Type t, Void s) {
3401 return high ? upperBound(t) : lowerBound(t);
3402 }
3404 @Override
3405 public Type visitCapturedType(CapturedType t, Void s) {
3406 return visitWildcardType(t.wildcard, null);
3407 }
3409 @Override
3410 public Type visitTypeVar(TypeVar t, Void s) {
3411 if (rewriteTypeVars)
3412 return high ? t.bound : syms.botType;
3413 else
3414 return t;
3415 }
3417 @Override
3418 public Type visitWildcardType(WildcardType t, Void s) {
3419 Type bound = high ? t.getExtendsBound() :
3420 t.getSuperBound();
3421 if (bound == null)
3422 bound = high ? syms.objectType : syms.botType;
3423 return bound;
3424 }
3425 }
3427 /**
3428 * Create a wildcard with the given upper (extends) bound; create
3429 * an unbounded wildcard if bound is Object.
3430 *
3431 * @param bound the upper bound
3432 * @param formal the formal type parameter that will be
3433 * substituted by the wildcard
3434 */
3435 private WildcardType makeExtendsWildcard(Type bound, TypeVar formal) {
3436 if (bound == syms.objectType) {
3437 return new WildcardType(syms.objectType,
3438 BoundKind.UNBOUND,
3439 syms.boundClass,
3440 formal);
3441 } else {
3442 return new WildcardType(bound,
3443 BoundKind.EXTENDS,
3444 syms.boundClass,
3445 formal);
3446 }
3447 }
3449 /**
3450 * Create a wildcard with the given lower (super) bound; create an
3451 * unbounded wildcard if bound is bottom (type of {@code null}).
3452 *
3453 * @param bound the lower bound
3454 * @param formal the formal type parameter that will be
3455 * substituted by the wildcard
3456 */
3457 private WildcardType makeSuperWildcard(Type bound, TypeVar formal) {
3458 if (bound.tag == BOT) {
3459 return new WildcardType(syms.objectType,
3460 BoundKind.UNBOUND,
3461 syms.boundClass,
3462 formal);
3463 } else {
3464 return new WildcardType(bound,
3465 BoundKind.SUPER,
3466 syms.boundClass,
3467 formal);
3468 }
3469 }
3471 /**
3472 * A wrapper for a type that allows use in sets.
3473 */
3474 class SingletonType {
3475 final Type t;
3476 SingletonType(Type t) {
3477 this.t = t;
3478 }
3479 public int hashCode() {
3480 return Types.this.hashCode(t);
3481 }
3482 public boolean equals(Object obj) {
3483 return (obj instanceof SingletonType) &&
3484 isSameType(t, ((SingletonType)obj).t);
3485 }
3486 public String toString() {
3487 return t.toString();
3488 }
3489 }
3490 // </editor-fold>
3492 // <editor-fold defaultstate="collapsed" desc="Visitors">
3493 /**
3494 * A default visitor for types. All visitor methods except
3495 * visitType are implemented by delegating to visitType. Concrete
3496 * subclasses must provide an implementation of visitType and can
3497 * override other methods as needed.
3498 *
3499 * @param <R> the return type of the operation implemented by this
3500 * visitor; use Void if no return type is needed.
3501 * @param <S> the type of the second argument (the first being the
3502 * type itself) of the operation implemented by this visitor; use
3503 * Void if a second argument is not needed.
3504 */
3505 public static abstract class DefaultTypeVisitor<R,S> implements Type.Visitor<R,S> {
3506 final public R visit(Type t, S s) { return t.accept(this, s); }
3507 public R visitClassType(ClassType t, S s) { return visitType(t, s); }
3508 public R visitWildcardType(WildcardType t, S s) { return visitType(t, s); }
3509 public R visitArrayType(ArrayType t, S s) { return visitType(t, s); }
3510 public R visitMethodType(MethodType t, S s) { return visitType(t, s); }
3511 public R visitPackageType(PackageType t, S s) { return visitType(t, s); }
3512 public R visitTypeVar(TypeVar t, S s) { return visitType(t, s); }
3513 public R visitCapturedType(CapturedType t, S s) { return visitType(t, s); }
3514 public R visitForAll(ForAll t, S s) { return visitType(t, s); }
3515 public R visitUndetVar(UndetVar t, S s) { return visitType(t, s); }
3516 public R visitErrorType(ErrorType t, S s) { return visitType(t, s); }
3517 }
3519 /**
3520 * A default visitor for symbols. All visitor methods except
3521 * visitSymbol are implemented by delegating to visitSymbol. Concrete
3522 * subclasses must provide an implementation of visitSymbol and can
3523 * override other methods as needed.
3524 *
3525 * @param <R> the return type of the operation implemented by this
3526 * visitor; use Void if no return type is needed.
3527 * @param <S> the type of the second argument (the first being the
3528 * symbol itself) of the operation implemented by this visitor; use
3529 * Void if a second argument is not needed.
3530 */
3531 public static abstract class DefaultSymbolVisitor<R,S> implements Symbol.Visitor<R,S> {
3532 final public R visit(Symbol s, S arg) { return s.accept(this, arg); }
3533 public R visitClassSymbol(ClassSymbol s, S arg) { return visitSymbol(s, arg); }
3534 public R visitMethodSymbol(MethodSymbol s, S arg) { return visitSymbol(s, arg); }
3535 public R visitOperatorSymbol(OperatorSymbol s, S arg) { return visitSymbol(s, arg); }
3536 public R visitPackageSymbol(PackageSymbol s, S arg) { return visitSymbol(s, arg); }
3537 public R visitTypeSymbol(TypeSymbol s, S arg) { return visitSymbol(s, arg); }
3538 public R visitVarSymbol(VarSymbol s, S arg) { return visitSymbol(s, arg); }
3539 }
3541 /**
3542 * A <em>simple</em> visitor for types. This visitor is simple as
3543 * captured wildcards, for-all types (generic methods), and
3544 * undetermined type variables (part of inference) are hidden.
3545 * Captured wildcards are hidden by treating them as type
3546 * variables and the rest are hidden by visiting their qtypes.
3547 *
3548 * @param <R> the return type of the operation implemented by this
3549 * visitor; use Void if no return type is needed.
3550 * @param <S> the type of the second argument (the first being the
3551 * type itself) of the operation implemented by this visitor; use
3552 * Void if a second argument is not needed.
3553 */
3554 public static abstract class SimpleVisitor<R,S> extends DefaultTypeVisitor<R,S> {
3555 @Override
3556 public R visitCapturedType(CapturedType t, S s) {
3557 return visitTypeVar(t, s);
3558 }
3559 @Override
3560 public R visitForAll(ForAll t, S s) {
3561 return visit(t.qtype, s);
3562 }
3563 @Override
3564 public R visitUndetVar(UndetVar t, S s) {
3565 return visit(t.qtype, s);
3566 }
3567 }
3569 /**
3570 * A plain relation on types. That is a 2-ary function on the
3571 * form Type × Type → Boolean.
3572 * <!-- In plain text: Type x Type -> Boolean -->
3573 */
3574 public static abstract class TypeRelation extends SimpleVisitor<Boolean,Type> {}
3576 /**
3577 * A convenience visitor for implementing operations that only
3578 * require one argument (the type itself), that is, unary
3579 * operations.
3580 *
3581 * @param <R> the return type of the operation implemented by this
3582 * visitor; use Void if no return type is needed.
3583 */
3584 public static abstract class UnaryVisitor<R> extends SimpleVisitor<R,Void> {
3585 final public R visit(Type t) { return t.accept(this, null); }
3586 }
3588 /**
3589 * A visitor for implementing a mapping from types to types. The
3590 * default behavior of this class is to implement the identity
3591 * mapping (mapping a type to itself). This can be overridden in
3592 * subclasses.
3593 *
3594 * @param <S> the type of the second argument (the first being the
3595 * type itself) of this mapping; use Void if a second argument is
3596 * not needed.
3597 */
3598 public static class MapVisitor<S> extends DefaultTypeVisitor<Type,S> {
3599 final public Type visit(Type t) { return t.accept(this, null); }
3600 public Type visitType(Type t, S s) { return t; }
3601 }
3602 // </editor-fold>
3603 }
