Mon, 04 Feb 2013 18:08:53 -0500
Merge
1 /*
2 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
26 package com.sun.tools.javac.code;
28 import java.util.Set;
29 import java.util.concurrent.Callable;
31 import javax.lang.model.element.*;
32 import javax.tools.JavaFileObject;
34 import com.sun.tools.javac.code.Type.*;
35 import com.sun.tools.javac.comp.Attr;
36 import com.sun.tools.javac.comp.AttrContext;
37 import com.sun.tools.javac.comp.Env;
38 import com.sun.tools.javac.jvm.*;
39 import com.sun.tools.javac.model.*;
40 import com.sun.tools.javac.tree.JCTree;
41 import com.sun.tools.javac.util.*;
42 import com.sun.tools.javac.util.Name;
43 import static com.sun.tools.javac.code.Flags.*;
44 import static com.sun.tools.javac.code.Kinds.*;
45 import static com.sun.tools.javac.code.TypeTag.CLASS;
46 import static com.sun.tools.javac.code.TypeTag.FORALL;
47 import static com.sun.tools.javac.code.TypeTag.TYPEVAR;
49 /** Root class for Java symbols. It contains subclasses
50 * for specific sorts of symbols, such as variables, methods and operators,
51 * types, packages. Each subclass is represented as a static inner class
52 * inside Symbol.
53 *
54 * <p><b>This is NOT part of any supported API.
55 * If you write code that depends on this, you do so at your own risk.
56 * This code and its internal interfaces are subject to change or
57 * deletion without notice.</b>
58 */
59 public abstract class Symbol implements Element {
60 // public Throwable debug = new Throwable();
62 /** The kind of this symbol.
63 * @see Kinds
64 */
65 public int kind;
67 /** The flags of this symbol.
68 */
69 public long flags_field;
71 /** An accessor method for the flags of this symbol.
72 * Flags of class symbols should be accessed through the accessor
73 * method to make sure that the class symbol is loaded.
74 */
75 public long flags() { return flags_field; }
77 /** The attributes of this symbol are contained in this
78 * Annotations. The Annotations instance is NOT immutable.
79 */
80 public final Annotations annotations = new Annotations(this);
82 /** An accessor method for the attributes of this symbol.
83 * Attributes of class symbols should be accessed through the accessor
84 * method to make sure that the class symbol is loaded.
85 */
86 public List<Attribute.Compound> getRawAttributes() {
87 return annotations.getDeclarationAttributes();
88 }
90 /** An accessor method for the type attributes of this symbol.
91 * Attributes of class symbols should be accessed through the accessor
92 * method to make sure that the class symbol is loaded.
93 */
94 public List<Attribute.TypeCompound> getRawTypeAttributes() {
95 return annotations.getTypeAttributes();
96 }
98 /** Fetch a particular annotation from a symbol. */
99 public Attribute.Compound attribute(Symbol anno) {
100 for (Attribute.Compound a : getRawAttributes()) {
101 if (a.type.tsym == anno) return a;
102 }
103 return null;
104 }
106 /** The name of this symbol in Utf8 representation.
107 */
108 public Name name;
110 /** The type of this symbol.
111 */
112 public Type type;
114 /** The owner of this symbol.
115 */
116 public Symbol owner;
118 /** The completer of this symbol.
119 */
120 public Completer completer;
122 /** A cache for the type erasure of this symbol.
123 */
124 public Type erasure_field;
126 /** Construct a symbol with given kind, flags, name, type and owner.
127 */
128 public Symbol(int kind, long flags, Name name, Type type, Symbol owner) {
129 this.kind = kind;
130 this.flags_field = flags;
131 this.type = type;
132 this.owner = owner;
133 this.completer = null;
134 this.erasure_field = null;
135 this.name = name;
136 }
138 /** Clone this symbol with new owner.
139 * Legal only for fields and methods.
140 */
141 public Symbol clone(Symbol newOwner) {
142 throw new AssertionError();
143 }
145 public <R, P> R accept(Symbol.Visitor<R, P> v, P p) {
146 return v.visitSymbol(this, p);
147 }
149 /** The Java source which this symbol represents.
150 * A description of this symbol; overrides Object.
151 */
152 public String toString() {
153 return name.toString();
154 }
156 /** A Java source description of the location of this symbol; used for
157 * error reporting.
158 *
159 * @return null if the symbol is a package or a toplevel class defined in
160 * the default package; otherwise, the owner symbol is returned
161 */
162 public Symbol location() {
163 if (owner.name == null || (owner.name.isEmpty() &&
164 (owner.flags() & BLOCK) == 0 && owner.kind != PCK && owner.kind != TYP)) {
165 return null;
166 }
167 return owner;
168 }
170 public Symbol location(Type site, Types types) {
171 if (owner.name == null || owner.name.isEmpty()) {
172 return location();
173 }
174 if (owner.type.hasTag(CLASS)) {
175 Type ownertype = types.asOuterSuper(site, owner);
176 if (ownertype != null) return ownertype.tsym;
177 }
178 return owner;
179 }
181 public Symbol baseSymbol() {
182 return this;
183 }
185 /** The symbol's erased type.
186 */
187 public Type erasure(Types types) {
188 if (erasure_field == null)
189 erasure_field = types.erasure(type);
190 return erasure_field;
191 }
193 /** The external type of a symbol. This is the symbol's erased type
194 * except for constructors of inner classes which get the enclosing
195 * instance class added as first argument.
196 */
197 public Type externalType(Types types) {
198 Type t = erasure(types);
199 if (name == name.table.names.init && owner.hasOuterInstance()) {
200 Type outerThisType = types.erasure(owner.type.getEnclosingType());
201 return new MethodType(t.getParameterTypes().prepend(outerThisType),
202 t.getReturnType(),
203 t.getThrownTypes(),
204 t.tsym);
205 } else {
206 return t;
207 }
208 }
210 public boolean isStatic() {
211 return
212 (flags() & STATIC) != 0 ||
213 (owner.flags() & INTERFACE) != 0 && kind != MTH;
214 }
216 public boolean isInterface() {
217 return (flags() & INTERFACE) != 0;
218 }
220 /** Is this symbol declared (directly or indirectly) local
221 * to a method or variable initializer?
222 * Also includes fields of inner classes which are in
223 * turn local to a method or variable initializer.
224 */
225 public boolean isLocal() {
226 return
227 (owner.kind & (VAR | MTH)) != 0 ||
228 (owner.kind == TYP && owner.isLocal());
229 }
231 /** Has this symbol an empty name? This includes anonymous
232 * inner classses.
233 */
234 public boolean isAnonymous() {
235 return name.isEmpty();
236 }
238 /** Is this symbol a constructor?
239 */
240 public boolean isConstructor() {
241 return name == name.table.names.init;
242 }
244 /** The fully qualified name of this symbol.
245 * This is the same as the symbol's name except for class symbols,
246 * which are handled separately.
247 */
248 public Name getQualifiedName() {
249 return name;
250 }
252 /** The fully qualified name of this symbol after converting to flat
253 * representation. This is the same as the symbol's name except for
254 * class symbols, which are handled separately.
255 */
256 public Name flatName() {
257 return getQualifiedName();
258 }
260 /** If this is a class or package, its members, otherwise null.
261 */
262 public Scope members() {
263 return null;
264 }
266 /** A class is an inner class if it it has an enclosing instance class.
267 */
268 public boolean isInner() {
269 return type.getEnclosingType().hasTag(CLASS);
270 }
272 /** An inner class has an outer instance if it is not an interface
273 * it has an enclosing instance class which might be referenced from the class.
274 * Nested classes can see instance members of their enclosing class.
275 * Their constructors carry an additional this$n parameter, inserted
276 * implicitly by the compiler.
277 *
278 * @see #isInner
279 */
280 public boolean hasOuterInstance() {
281 return
282 type.getEnclosingType().hasTag(CLASS) && (flags() & (INTERFACE | NOOUTERTHIS)) == 0;
283 }
285 /** The closest enclosing class of this symbol's declaration.
286 */
287 public ClassSymbol enclClass() {
288 Symbol c = this;
289 while (c != null &&
290 ((c.kind & TYP) == 0 || !c.type.hasTag(CLASS))) {
291 c = c.owner;
292 }
293 return (ClassSymbol)c;
294 }
296 /** The outermost class which indirectly owns this symbol.
297 */
298 public ClassSymbol outermostClass() {
299 Symbol sym = this;
300 Symbol prev = null;
301 while (sym.kind != PCK) {
302 prev = sym;
303 sym = sym.owner;
304 }
305 return (ClassSymbol) prev;
306 }
308 /** The package which indirectly owns this symbol.
309 */
310 public PackageSymbol packge() {
311 Symbol sym = this;
312 while (sym.kind != PCK) {
313 sym = sym.owner;
314 }
315 return (PackageSymbol) sym;
316 }
318 /** Is this symbol a subclass of `base'? Only defined for ClassSymbols.
319 */
320 public boolean isSubClass(Symbol base, Types types) {
321 throw new AssertionError("isSubClass " + this);
322 }
324 /** Fully check membership: hierarchy, protection, and hiding.
325 * Does not exclude methods not inherited due to overriding.
326 */
327 public boolean isMemberOf(TypeSymbol clazz, Types types) {
328 return
329 owner == clazz ||
330 clazz.isSubClass(owner, types) &&
331 isInheritedIn(clazz, types) &&
332 !hiddenIn((ClassSymbol)clazz, types);
333 }
335 /** Is this symbol the same as or enclosed by the given class? */
336 public boolean isEnclosedBy(ClassSymbol clazz) {
337 for (Symbol sym = this; sym.kind != PCK; sym = sym.owner)
338 if (sym == clazz) return true;
339 return false;
340 }
342 /** Check for hiding. Note that this doesn't handle multiple
343 * (interface) inheritance. */
344 private boolean hiddenIn(ClassSymbol clazz, Types types) {
345 if (kind == MTH && (flags() & STATIC) == 0) return false;
346 while (true) {
347 if (owner == clazz) return false;
348 Scope.Entry e = clazz.members().lookup(name);
349 while (e.scope != null) {
350 if (e.sym == this) return false;
351 if (e.sym.kind == kind &&
352 (kind != MTH ||
353 (e.sym.flags() & STATIC) != 0 &&
354 types.isSubSignature(e.sym.type, type)))
355 return true;
356 e = e.next();
357 }
358 Type superType = types.supertype(clazz.type);
359 if (!superType.hasTag(CLASS)) return false;
360 clazz = (ClassSymbol)superType.tsym;
361 }
362 }
364 /** Is this symbol inherited into a given class?
365 * PRE: If symbol's owner is a interface,
366 * it is already assumed that the interface is a superinterface
367 * of given class.
368 * @param clazz The class for which we want to establish membership.
369 * This must be a subclass of the member's owner.
370 */
371 public boolean isInheritedIn(Symbol clazz, Types types) {
372 switch ((int)(flags_field & Flags.AccessFlags)) {
373 default: // error recovery
374 case PUBLIC:
375 return true;
376 case PRIVATE:
377 return this.owner == clazz;
378 case PROTECTED:
379 // we model interfaces as extending Object
380 return (clazz.flags() & INTERFACE) == 0;
381 case 0:
382 PackageSymbol thisPackage = this.packge();
383 for (Symbol sup = clazz;
384 sup != null && sup != this.owner;
385 sup = types.supertype(sup.type).tsym) {
386 while (sup.type.hasTag(TYPEVAR))
387 sup = sup.type.getUpperBound().tsym;
388 if (sup.type.isErroneous())
389 return true; // error recovery
390 if ((sup.flags() & COMPOUND) != 0)
391 continue;
392 if (sup.packge() != thisPackage)
393 return false;
394 }
395 return (clazz.flags() & INTERFACE) == 0;
396 }
397 }
399 /** The (variable or method) symbol seen as a member of given
400 * class type`site' (this might change the symbol's type).
401 * This is used exclusively for producing diagnostics.
402 */
403 public Symbol asMemberOf(Type site, Types types) {
404 throw new AssertionError();
405 }
407 /** Does this method symbol override `other' symbol, when both are seen as
408 * members of class `origin'? It is assumed that _other is a member
409 * of origin.
410 *
411 * It is assumed that both symbols have the same name. The static
412 * modifier is ignored for this test.
413 *
414 * See JLS 8.4.6.1 (without transitivity) and 8.4.6.4
415 */
416 public boolean overrides(Symbol _other, TypeSymbol origin, Types types, boolean checkResult) {
417 return false;
418 }
420 /** Complete the elaboration of this symbol's definition.
421 */
422 public void complete() throws CompletionFailure {
423 if (completer != null) {
424 Completer c = completer;
425 completer = null;
426 c.complete(this);
427 }
428 }
430 /** True if the symbol represents an entity that exists.
431 */
432 public boolean exists() {
433 return true;
434 }
436 public Type asType() {
437 return type;
438 }
440 public Symbol getEnclosingElement() {
441 return owner;
442 }
444 public ElementKind getKind() {
445 return ElementKind.OTHER; // most unkind
446 }
448 public Set<Modifier> getModifiers() {
449 long flags = flags();
450 return Flags.asModifierSet((flags & DEFAULT) != 0 ? flags & ~ABSTRACT : flags);
451 }
453 public Name getSimpleName() {
454 return name;
455 }
457 /**
458 * This is the implementation for {@code
459 * javax.lang.model.element.Element.getAnnotationMirrors()}.
460 */
461 public final List<? extends AnnotationMirror> getAnnotationMirrors() {
462 return getRawAttributes();
463 }
465 /**
466 * TODO: Should there be a {@code
467 * javax.lang.model.element.Element.getTypeAnnotationMirrors()}.
468 */
469 public final List<Attribute.TypeCompound> getTypeAnnotationMirrors() {
470 return getRawTypeAttributes();
471 }
473 /**
474 * @deprecated this method should never be used by javac internally.
475 */
476 @Deprecated
477 public <A extends java.lang.annotation.Annotation> A getAnnotation(Class<A> annoType) {
478 return JavacElements.getAnnotation(this, annoType);
479 }
481 // This method is part of the javax.lang.model API, do not use this in javac code.
482 public <A extends java.lang.annotation.Annotation> A[] getAnnotations(Class<A> annoType) {
483 return JavacElements.getAnnotations(this, annoType);
484 }
486 // TODO: getEnclosedElements should return a javac List, fix in FilteredMemberList
487 public java.util.List<Symbol> getEnclosedElements() {
488 return List.nil();
489 }
491 public List<TypeSymbol> getTypeParameters() {
492 ListBuffer<TypeSymbol> l = ListBuffer.lb();
493 for (Type t : type.getTypeArguments()) {
494 l.append(t.tsym);
495 }
496 return l.toList();
497 }
499 public static class DelegatedSymbol extends Symbol {
500 protected Symbol other;
501 public DelegatedSymbol(Symbol other) {
502 super(other.kind, other.flags_field, other.name, other.type, other.owner);
503 this.other = other;
504 }
505 public String toString() { return other.toString(); }
506 public Symbol location() { return other.location(); }
507 public Symbol location(Type site, Types types) { return other.location(site, types); }
508 public Symbol baseSymbol() { return other; }
509 public Type erasure(Types types) { return other.erasure(types); }
510 public Type externalType(Types types) { return other.externalType(types); }
511 public boolean isLocal() { return other.isLocal(); }
512 public boolean isConstructor() { return other.isConstructor(); }
513 public Name getQualifiedName() { return other.getQualifiedName(); }
514 public Name flatName() { return other.flatName(); }
515 public Scope members() { return other.members(); }
516 public boolean isInner() { return other.isInner(); }
517 public boolean hasOuterInstance() { return other.hasOuterInstance(); }
518 public ClassSymbol enclClass() { return other.enclClass(); }
519 public ClassSymbol outermostClass() { return other.outermostClass(); }
520 public PackageSymbol packge() { return other.packge(); }
521 public boolean isSubClass(Symbol base, Types types) { return other.isSubClass(base, types); }
522 public boolean isMemberOf(TypeSymbol clazz, Types types) { return other.isMemberOf(clazz, types); }
523 public boolean isEnclosedBy(ClassSymbol clazz) { return other.isEnclosedBy(clazz); }
524 public boolean isInheritedIn(Symbol clazz, Types types) { return other.isInheritedIn(clazz, types); }
525 public Symbol asMemberOf(Type site, Types types) { return other.asMemberOf(site, types); }
526 public void complete() throws CompletionFailure { other.complete(); }
528 public <R, P> R accept(ElementVisitor<R, P> v, P p) {
529 return other.accept(v, p);
530 }
532 public <R, P> R accept(Symbol.Visitor<R, P> v, P p) {
533 return v.visitSymbol(other, p);
534 }
535 }
537 /** A class for type symbols. Type variables are represented by instances
538 * of this class, classes and packages by instances of subclasses.
539 */
540 public static class TypeSymbol
541 extends Symbol implements TypeParameterElement {
542 // Implements TypeParameterElement because type parameters don't
543 // have their own TypeSymbol subclass.
544 // TODO: type parameters should have their own TypeSymbol subclass
546 public TypeSymbol(long flags, Name name, Type type, Symbol owner) {
547 super(TYP, flags, name, type, owner);
548 }
550 /** form a fully qualified name from a name and an owner
551 */
552 static public Name formFullName(Name name, Symbol owner) {
553 if (owner == null) return name;
554 if (((owner.kind != ERR)) &&
555 ((owner.kind & (VAR | MTH)) != 0
556 || (owner.kind == TYP && owner.type.hasTag(TYPEVAR))
557 )) return name;
558 Name prefix = owner.getQualifiedName();
559 if (prefix == null || prefix == prefix.table.names.empty)
560 return name;
561 else return prefix.append('.', name);
562 }
564 /** form a fully qualified name from a name and an owner, after
565 * converting to flat representation
566 */
567 static public Name formFlatName(Name name, Symbol owner) {
568 if (owner == null ||
569 (owner.kind & (VAR | MTH)) != 0
570 || (owner.kind == TYP && owner.type.hasTag(TYPEVAR))
571 ) return name;
572 char sep = owner.kind == TYP ? '$' : '.';
573 Name prefix = owner.flatName();
574 if (prefix == null || prefix == prefix.table.names.empty)
575 return name;
576 else return prefix.append(sep, name);
577 }
579 /**
580 * A total ordering between type symbols that refines the
581 * class inheritance graph.
582 *
583 * Typevariables always precede other kinds of symbols.
584 */
585 public final boolean precedes(TypeSymbol that, Types types) {
586 if (this == that)
587 return false;
588 if (this.type.tag == that.type.tag) {
589 if (this.type.hasTag(CLASS)) {
590 return
591 types.rank(that.type) < types.rank(this.type) ||
592 types.rank(that.type) == types.rank(this.type) &&
593 that.getQualifiedName().compareTo(this.getQualifiedName()) < 0;
594 } else if (this.type.hasTag(TYPEVAR)) {
595 return types.isSubtype(this.type, that.type);
596 }
597 }
598 return this.type.hasTag(TYPEVAR);
599 }
601 // For type params; overridden in subclasses.
602 public ElementKind getKind() {
603 return ElementKind.TYPE_PARAMETER;
604 }
606 public java.util.List<Symbol> getEnclosedElements() {
607 List<Symbol> list = List.nil();
608 if (kind == TYP && type.hasTag(TYPEVAR)) {
609 return list;
610 }
611 for (Scope.Entry e = members().elems; e != null; e = e.sibling) {
612 if (e.sym != null && (e.sym.flags() & SYNTHETIC) == 0 && e.sym.owner == this)
613 list = list.prepend(e.sym);
614 }
615 return list;
616 }
618 // For type params.
619 // Perhaps not needed if getEnclosingElement can be spec'ed
620 // to do the same thing.
621 // TODO: getGenericElement() might not be needed
622 public Symbol getGenericElement() {
623 return owner;
624 }
626 public <R, P> R accept(ElementVisitor<R, P> v, P p) {
627 Assert.check(type.hasTag(TYPEVAR)); // else override will be invoked
628 return v.visitTypeParameter(this, p);
629 }
631 public <R, P> R accept(Symbol.Visitor<R, P> v, P p) {
632 return v.visitTypeSymbol(this, p);
633 }
635 public List<Type> getBounds() {
636 TypeVar t = (TypeVar)type;
637 Type bound = t.getUpperBound();
638 if (!bound.isCompound())
639 return List.of(bound);
640 ClassType ct = (ClassType)bound;
641 if (!ct.tsym.erasure_field.isInterface()) {
642 return ct.interfaces_field.prepend(ct.supertype_field);
643 } else {
644 // No superclass was given in bounds.
645 // In this case, supertype is Object, erasure is first interface.
646 return ct.interfaces_field;
647 }
648 }
649 }
651 /** A class for package symbols
652 */
653 public static class PackageSymbol extends TypeSymbol
654 implements PackageElement {
656 public Scope members_field;
657 public Name fullname;
658 public ClassSymbol package_info; // see bug 6443073
660 public PackageSymbol(Name name, Type type, Symbol owner) {
661 super(0, name, type, owner);
662 this.kind = PCK;
663 this.members_field = null;
664 this.fullname = formFullName(name, owner);
665 }
667 public PackageSymbol(Name name, Symbol owner) {
668 this(name, null, owner);
669 this.type = new PackageType(this);
670 }
672 public String toString() {
673 return fullname.toString();
674 }
676 public Name getQualifiedName() {
677 return fullname;
678 }
680 public boolean isUnnamed() {
681 return name.isEmpty() && owner != null;
682 }
684 public Scope members() {
685 if (completer != null) complete();
686 return members_field;
687 }
689 public long flags() {
690 if (completer != null) complete();
691 return flags_field;
692 }
694 @Override
695 public List<Attribute.Compound> getRawAttributes() {
696 if (completer != null) complete();
697 if (package_info != null && package_info.completer != null) {
698 package_info.complete();
699 mergeAttributes();
700 }
701 return super.getRawAttributes();
702 }
704 private void mergeAttributes() {
705 if (annotations.isEmpty() &&
706 !package_info.annotations.isEmpty()) {
707 annotations.setAttributes(package_info.annotations);
708 }
709 }
711 /** A package "exists" if a type or package that exists has
712 * been seen within it.
713 */
714 public boolean exists() {
715 return (flags_field & EXISTS) != 0;
716 }
718 public ElementKind getKind() {
719 return ElementKind.PACKAGE;
720 }
722 public Symbol getEnclosingElement() {
723 return null;
724 }
726 public <R, P> R accept(ElementVisitor<R, P> v, P p) {
727 return v.visitPackage(this, p);
728 }
730 public <R, P> R accept(Symbol.Visitor<R, P> v, P p) {
731 return v.visitPackageSymbol(this, p);
732 }
733 }
735 /** A class for class symbols
736 */
737 public static class ClassSymbol extends TypeSymbol implements TypeElement {
739 /** a scope for all class members; variables, methods and inner classes
740 * type parameters are not part of this scope
741 */
742 public Scope members_field;
744 /** the fully qualified name of the class, i.e. pck.outer.inner.
745 * null for anonymous classes
746 */
747 public Name fullname;
749 /** the fully qualified name of the class after converting to flat
750 * representation, i.e. pck.outer$inner,
751 * set externally for local and anonymous classes
752 */
753 public Name flatname;
755 /** the sourcefile where the class came from
756 */
757 public JavaFileObject sourcefile;
759 /** the classfile from where to load this class
760 * this will have extension .class or .java
761 */
762 public JavaFileObject classfile;
764 /** the list of translated local classes (used for generating
765 * InnerClasses attribute)
766 */
767 public List<ClassSymbol> trans_local;
769 /** the constant pool of the class
770 */
771 public Pool pool;
773 public ClassSymbol(long flags, Name name, Type type, Symbol owner) {
774 super(flags, name, type, owner);
775 this.members_field = null;
776 this.fullname = formFullName(name, owner);
777 this.flatname = formFlatName(name, owner);
778 this.sourcefile = null;
779 this.classfile = null;
780 this.pool = null;
781 }
783 public ClassSymbol(long flags, Name name, Symbol owner) {
784 this(
785 flags,
786 name,
787 new ClassType(Type.noType, null, null),
788 owner);
789 this.type.tsym = this;
790 }
792 /** The Java source which this symbol represents.
793 */
794 public String toString() {
795 return className();
796 }
798 public long flags() {
799 if (completer != null) complete();
800 return flags_field;
801 }
803 public Scope members() {
804 if (completer != null) complete();
805 return members_field;
806 }
808 @Override
809 public List<Attribute.Compound> getRawAttributes() {
810 if (completer != null) complete();
811 return super.getRawAttributes();
812 }
814 @Override
815 public List<Attribute.TypeCompound> getRawTypeAttributes() {
816 if (completer != null) complete();
817 return super.getRawTypeAttributes();
818 }
820 public Type erasure(Types types) {
821 if (erasure_field == null)
822 erasure_field = new ClassType(types.erasure(type.getEnclosingType()),
823 List.<Type>nil(), this);
824 return erasure_field;
825 }
827 public String className() {
828 if (name.isEmpty())
829 return
830 Log.getLocalizedString("anonymous.class", flatname);
831 else
832 return fullname.toString();
833 }
835 public Name getQualifiedName() {
836 return fullname;
837 }
839 public Name flatName() {
840 return flatname;
841 }
843 public boolean isSubClass(Symbol base, Types types) {
844 if (this == base) {
845 return true;
846 } else if ((base.flags() & INTERFACE) != 0) {
847 for (Type t = type; t.hasTag(CLASS); t = types.supertype(t))
848 for (List<Type> is = types.interfaces(t);
849 is.nonEmpty();
850 is = is.tail)
851 if (is.head.tsym.isSubClass(base, types)) return true;
852 } else {
853 for (Type t = type; t.hasTag(CLASS); t = types.supertype(t))
854 if (t.tsym == base) return true;
855 }
856 return false;
857 }
859 /** Complete the elaboration of this symbol's definition.
860 */
861 public void complete() throws CompletionFailure {
862 try {
863 super.complete();
864 } catch (CompletionFailure ex) {
865 // quiet error recovery
866 flags_field |= (PUBLIC|STATIC);
867 this.type = new ErrorType(this, Type.noType);
868 throw ex;
869 }
870 }
872 public List<Type> getInterfaces() {
873 complete();
874 if (type instanceof ClassType) {
875 ClassType t = (ClassType)type;
876 if (t.interfaces_field == null) // FIXME: shouldn't be null
877 t.interfaces_field = List.nil();
878 if (t.all_interfaces_field != null)
879 return Type.getModelTypes(t.all_interfaces_field);
880 return t.interfaces_field;
881 } else {
882 return List.nil();
883 }
884 }
886 public Type getSuperclass() {
887 complete();
888 if (type instanceof ClassType) {
889 ClassType t = (ClassType)type;
890 if (t.supertype_field == null) // FIXME: shouldn't be null
891 t.supertype_field = Type.noType;
892 // An interface has no superclass; its supertype is Object.
893 return t.isInterface()
894 ? Type.noType
895 : t.supertype_field.getModelType();
896 } else {
897 return Type.noType;
898 }
899 }
901 public ElementKind getKind() {
902 long flags = flags();
903 if ((flags & ANNOTATION) != 0)
904 return ElementKind.ANNOTATION_TYPE;
905 else if ((flags & INTERFACE) != 0)
906 return ElementKind.INTERFACE;
907 else if ((flags & ENUM) != 0)
908 return ElementKind.ENUM;
909 else
910 return ElementKind.CLASS;
911 }
913 public NestingKind getNestingKind() {
914 complete();
915 if (owner.kind == PCK)
916 return NestingKind.TOP_LEVEL;
917 else if (name.isEmpty())
918 return NestingKind.ANONYMOUS;
919 else if (owner.kind == MTH)
920 return NestingKind.LOCAL;
921 else
922 return NestingKind.MEMBER;
923 }
925 /**
926 * @deprecated this method should never be used by javac internally.
927 */
928 @Override @Deprecated
929 public <A extends java.lang.annotation.Annotation> A getAnnotation(Class<A> annoType) {
930 return JavacElements.getAnnotation(this, annoType);
931 }
933 public <R, P> R accept(ElementVisitor<R, P> v, P p) {
934 return v.visitType(this, p);
935 }
937 public <R, P> R accept(Symbol.Visitor<R, P> v, P p) {
938 return v.visitClassSymbol(this, p);
939 }
940 }
943 /** A class for variable symbols
944 */
945 public static class VarSymbol extends Symbol implements VariableElement {
947 /** The variable's declaration position.
948 */
949 public int pos = Position.NOPOS;
951 /** The variable's address. Used for different purposes during
952 * flow analysis, translation and code generation.
953 * Flow analysis:
954 * If this is a blank final or local variable, its sequence number.
955 * Translation:
956 * If this is a private field, its access number.
957 * Code generation:
958 * If this is a local variable, its logical slot number.
959 */
960 public int adr = -1;
962 /** Construct a variable symbol, given its flags, name, type and owner.
963 */
964 public VarSymbol(long flags, Name name, Type type, Symbol owner) {
965 super(VAR, flags, name, type, owner);
966 }
968 /** Clone this symbol with new owner.
969 */
970 public VarSymbol clone(Symbol newOwner) {
971 VarSymbol v = new VarSymbol(flags_field, name, type, newOwner) {
972 @Override
973 public Symbol baseSymbol() {
974 return VarSymbol.this;
975 }
976 };
977 v.pos = pos;
978 v.adr = adr;
979 v.data = data;
980 // System.out.println("clone " + v + " in " + newOwner);//DEBUG
981 return v;
982 }
984 public String toString() {
985 return name.toString();
986 }
988 public Symbol asMemberOf(Type site, Types types) {
989 return new VarSymbol(flags_field, name, types.memberType(site, this), owner);
990 }
992 public ElementKind getKind() {
993 long flags = flags();
994 if ((flags & PARAMETER) != 0) {
995 if (isExceptionParameter())
996 return ElementKind.EXCEPTION_PARAMETER;
997 else
998 return ElementKind.PARAMETER;
999 } else if ((flags & ENUM) != 0) {
1000 return ElementKind.ENUM_CONSTANT;
1001 } else if (owner.kind == TYP || owner.kind == ERR) {
1002 return ElementKind.FIELD;
1003 } else if (isResourceVariable()) {
1004 return ElementKind.RESOURCE_VARIABLE;
1005 } else {
1006 return ElementKind.LOCAL_VARIABLE;
1007 }
1008 }
1010 public <R, P> R accept(ElementVisitor<R, P> v, P p) {
1011 return v.visitVariable(this, p);
1012 }
1014 public Object getConstantValue() { // Mirror API
1015 return Constants.decode(getConstValue(), type);
1016 }
1018 public void setLazyConstValue(final Env<AttrContext> env,
1019 final Attr attr,
1020 final JCTree.JCExpression initializer)
1021 {
1022 setData(new Callable<Object>() {
1023 public Object call() {
1024 return attr.attribLazyConstantValue(env, initializer, type);
1025 }
1026 });
1027 }
1029 /**
1030 * The variable's constant value, if this is a constant.
1031 * Before the constant value is evaluated, it points to an
1032 * initalizer environment. If this is not a constant, it can
1033 * be used for other stuff.
1034 */
1035 private Object data;
1037 public boolean isExceptionParameter() {
1038 return data == ElementKind.EXCEPTION_PARAMETER;
1039 }
1041 public boolean isResourceVariable() {
1042 return data == ElementKind.RESOURCE_VARIABLE;
1043 }
1045 public Object getConstValue() {
1046 // TODO: Consider if getConstValue and getConstantValue can be collapsed
1047 if (data == ElementKind.EXCEPTION_PARAMETER ||
1048 data == ElementKind.RESOURCE_VARIABLE) {
1049 return null;
1050 } else if (data instanceof Callable<?>) {
1051 // In this case, this is a final variable, with an as
1052 // yet unevaluated initializer.
1053 Callable<?> eval = (Callable<?>)data;
1054 data = null; // to make sure we don't evaluate this twice.
1055 try {
1056 data = eval.call();
1057 } catch (Exception ex) {
1058 throw new AssertionError(ex);
1059 }
1060 }
1061 return data;
1062 }
1064 public void setData(Object data) {
1065 Assert.check(!(data instanceof Env<?>), this);
1066 this.data = data;
1067 }
1069 public <R, P> R accept(Symbol.Visitor<R, P> v, P p) {
1070 return v.visitVarSymbol(this, p);
1071 }
1072 }
1074 /** A class for method symbols.
1075 */
1076 public static class MethodSymbol extends Symbol implements ExecutableElement {
1078 /** The code of the method. */
1079 public Code code = null;
1081 /** The parameters of the method. */
1082 public List<VarSymbol> params = null;
1084 /** The names of the parameters */
1085 public List<Name> savedParameterNames;
1087 /** For an attribute field accessor, its default value if any.
1088 * The value is null if none appeared in the method
1089 * declaration.
1090 */
1091 public Attribute defaultValue = null;
1093 /** Construct a method symbol, given its flags, name, type and owner.
1094 */
1095 public MethodSymbol(long flags, Name name, Type type, Symbol owner) {
1096 super(MTH, flags, name, type, owner);
1097 if (owner.type.hasTag(TYPEVAR)) Assert.error(owner + "." + name);
1098 }
1100 /** Clone this symbol with new owner.
1101 */
1102 public MethodSymbol clone(Symbol newOwner) {
1103 MethodSymbol m = new MethodSymbol(flags_field, name, type, newOwner) {
1104 @Override
1105 public Symbol baseSymbol() {
1106 return MethodSymbol.this;
1107 }
1108 };
1109 m.code = code;
1110 return m;
1111 }
1113 /** The Java source which this symbol represents.
1114 */
1115 public String toString() {
1116 if ((flags() & BLOCK) != 0) {
1117 return owner.name.toString();
1118 } else {
1119 String s = (name == name.table.names.init)
1120 ? owner.name.toString()
1121 : name.toString();
1122 if (type != null) {
1123 if (type.hasTag(FORALL))
1124 s = "<" + ((ForAll)type).getTypeArguments() + ">" + s;
1125 s += "(" + type.argtypes((flags() & VARARGS) != 0) + ")";
1126 }
1127 return s;
1128 }
1129 }
1131 public boolean isDynamic() {
1132 return false;
1133 }
1135 /** find a symbol that this (proxy method) symbol implements.
1136 * @param c The class whose members are searched for
1137 * implementations
1138 */
1139 public Symbol implemented(TypeSymbol c, Types types) {
1140 Symbol impl = null;
1141 for (List<Type> is = types.interfaces(c.type);
1142 impl == null && is.nonEmpty();
1143 is = is.tail) {
1144 TypeSymbol i = is.head.tsym;
1145 impl = implementedIn(i, types);
1146 if (impl == null)
1147 impl = implemented(i, types);
1148 }
1149 return impl;
1150 }
1152 public Symbol implementedIn(TypeSymbol c, Types types) {
1153 Symbol impl = null;
1154 for (Scope.Entry e = c.members().lookup(name);
1155 impl == null && e.scope != null;
1156 e = e.next()) {
1157 if (this.overrides(e.sym, (TypeSymbol)owner, types, true) &&
1158 // FIXME: I suspect the following requires a
1159 // subst() for a parametric return type.
1160 types.isSameType(type.getReturnType(),
1161 types.memberType(owner.type, e.sym).getReturnType())) {
1162 impl = e.sym;
1163 }
1164 }
1165 return impl;
1166 }
1168 /** Will the erasure of this method be considered by the VM to
1169 * override the erasure of the other when seen from class `origin'?
1170 */
1171 public boolean binaryOverrides(Symbol _other, TypeSymbol origin, Types types) {
1172 if (isConstructor() || _other.kind != MTH) return false;
1174 if (this == _other) return true;
1175 MethodSymbol other = (MethodSymbol)_other;
1177 // check for a direct implementation
1178 if (other.isOverridableIn((TypeSymbol)owner) &&
1179 types.asSuper(owner.type, other.owner) != null &&
1180 types.isSameType(erasure(types), other.erasure(types)))
1181 return true;
1183 // check for an inherited implementation
1184 return
1185 (flags() & ABSTRACT) == 0 &&
1186 other.isOverridableIn(origin) &&
1187 this.isMemberOf(origin, types) &&
1188 types.isSameType(erasure(types), other.erasure(types));
1189 }
1191 /** The implementation of this (abstract) symbol in class origin,
1192 * from the VM's point of view, null if method does not have an
1193 * implementation in class.
1194 * @param origin The class of which the implementation is a member.
1195 */
1196 public MethodSymbol binaryImplementation(ClassSymbol origin, Types types) {
1197 for (TypeSymbol c = origin; c != null; c = types.supertype(c.type).tsym) {
1198 for (Scope.Entry e = c.members().lookup(name);
1199 e.scope != null;
1200 e = e.next()) {
1201 if (e.sym.kind == MTH &&
1202 ((MethodSymbol)e.sym).binaryOverrides(this, origin, types))
1203 return (MethodSymbol)e.sym;
1204 }
1205 }
1206 return null;
1207 }
1209 /** Does this symbol override `other' symbol, when both are seen as
1210 * members of class `origin'? It is assumed that _other is a member
1211 * of origin.
1212 *
1213 * It is assumed that both symbols have the same name. The static
1214 * modifier is ignored for this test.
1215 *
1216 * See JLS 8.4.6.1 (without transitivity) and 8.4.6.4
1217 */
1218 public boolean overrides(Symbol _other, TypeSymbol origin, Types types, boolean checkResult) {
1219 if (isConstructor() || _other.kind != MTH) return false;
1221 if (this == _other) return true;
1222 MethodSymbol other = (MethodSymbol)_other;
1224 // check for a direct implementation
1225 if (other.isOverridableIn((TypeSymbol)owner) &&
1226 types.asSuper(owner.type, other.owner) != null) {
1227 Type mt = types.memberType(owner.type, this);
1228 Type ot = types.memberType(owner.type, other);
1229 if (types.isSubSignature(mt, ot)) {
1230 if (!checkResult)
1231 return true;
1232 if (types.returnTypeSubstitutable(mt, ot))
1233 return true;
1234 }
1235 }
1237 // check for an inherited implementation
1238 if ((flags() & ABSTRACT) != 0 ||
1239 ((other.flags() & ABSTRACT) == 0 && (other.flags() & DEFAULT) == 0) ||
1240 !other.isOverridableIn(origin) ||
1241 !this.isMemberOf(origin, types))
1242 return false;
1244 // assert types.asSuper(origin.type, other.owner) != null;
1245 Type mt = types.memberType(origin.type, this);
1246 Type ot = types.memberType(origin.type, other);
1247 return
1248 types.isSubSignature(mt, ot) &&
1249 (!checkResult || types.resultSubtype(mt, ot, types.noWarnings));
1250 }
1252 private boolean isOverridableIn(TypeSymbol origin) {
1253 // JLS 8.4.6.1
1254 switch ((int)(flags_field & Flags.AccessFlags)) {
1255 case Flags.PRIVATE:
1256 return false;
1257 case Flags.PUBLIC:
1258 return !this.owner.isInterface() ||
1259 (flags_field & STATIC) == 0;
1260 case Flags.PROTECTED:
1261 return (origin.flags() & INTERFACE) == 0;
1262 case 0:
1263 // for package private: can only override in the same
1264 // package
1265 return
1266 this.packge() == origin.packge() &&
1267 (origin.flags() & INTERFACE) == 0;
1268 default:
1269 return false;
1270 }
1271 }
1273 @Override
1274 public boolean isInheritedIn(Symbol clazz, Types types) {
1275 switch ((int)(flags_field & Flags.AccessFlags)) {
1276 case PUBLIC:
1277 return !this.owner.isInterface() ||
1278 clazz == owner ||
1279 (flags_field & STATIC) == 0;
1280 default:
1281 return super.isInheritedIn(clazz, types);
1282 }
1283 }
1285 /** The implementation of this (abstract) symbol in class origin;
1286 * null if none exists. Synthetic methods are not considered
1287 * as possible implementations.
1288 */
1289 public MethodSymbol implementation(TypeSymbol origin, Types types, boolean checkResult) {
1290 return implementation(origin, types, checkResult, implementation_filter);
1291 }
1292 // where
1293 private static final Filter<Symbol> implementation_filter = new Filter<Symbol>() {
1294 public boolean accepts(Symbol s) {
1295 return s.kind == Kinds.MTH &&
1296 (s.flags() & SYNTHETIC) == 0;
1297 }
1298 };
1300 public MethodSymbol implementation(TypeSymbol origin, Types types, boolean checkResult, Filter<Symbol> implFilter) {
1301 MethodSymbol res = types.implementation(this, origin, checkResult, implFilter);
1302 if (res != null)
1303 return res;
1304 // if origin is derived from a raw type, we might have missed
1305 // an implementation because we do not know enough about instantiations.
1306 // in this case continue with the supertype as origin.
1307 if (types.isDerivedRaw(origin.type) && !origin.isInterface())
1308 return implementation(types.supertype(origin.type).tsym, types, checkResult);
1309 else
1310 return null;
1311 }
1313 public List<VarSymbol> params() {
1314 owner.complete();
1315 if (params == null) {
1316 // If ClassReader.saveParameterNames has been set true, then
1317 // savedParameterNames will be set to a list of names that
1318 // matches the types in type.getParameterTypes(). If any names
1319 // were not found in the class file, those names in the list will
1320 // be set to the empty name.
1321 // If ClassReader.saveParameterNames has been set false, then
1322 // savedParameterNames will be null.
1323 List<Name> paramNames = savedParameterNames;
1324 savedParameterNames = null;
1325 // discard the provided names if the list of names is the wrong size.
1326 if (paramNames == null || paramNames.size() != type.getParameterTypes().size()) {
1327 paramNames = List.nil();
1328 }
1329 ListBuffer<VarSymbol> buf = new ListBuffer<VarSymbol>();
1330 List<Name> remaining = paramNames;
1331 // assert: remaining and paramNames are both empty or both
1332 // have same cardinality as type.getParameterTypes()
1333 int i = 0;
1334 for (Type t : type.getParameterTypes()) {
1335 Name paramName;
1336 if (remaining.isEmpty()) {
1337 // no names for any parameters available
1338 paramName = createArgName(i, paramNames);
1339 } else {
1340 paramName = remaining.head;
1341 remaining = remaining.tail;
1342 if (paramName.isEmpty()) {
1343 // no name for this specific parameter
1344 paramName = createArgName(i, paramNames);
1345 }
1346 }
1347 buf.append(new VarSymbol(PARAMETER, paramName, t, this));
1348 i++;
1349 }
1350 params = buf.toList();
1351 }
1352 return params;
1353 }
1355 // Create a name for the argument at position 'index' that is not in
1356 // the exclude list. In normal use, either no names will have been
1357 // provided, in which case the exclude list is empty, or all the names
1358 // will have been provided, in which case this method will not be called.
1359 private Name createArgName(int index, List<Name> exclude) {
1360 String prefix = "arg";
1361 while (true) {
1362 Name argName = name.table.fromString(prefix + index);
1363 if (!exclude.contains(argName))
1364 return argName;
1365 prefix += "$";
1366 }
1367 }
1369 public Symbol asMemberOf(Type site, Types types) {
1370 return new MethodSymbol(flags_field, name, types.memberType(site, this), owner);
1371 }
1373 public ElementKind getKind() {
1374 if (name == name.table.names.init)
1375 return ElementKind.CONSTRUCTOR;
1376 else if (name == name.table.names.clinit)
1377 return ElementKind.STATIC_INIT;
1378 else if ((flags() & BLOCK) != 0)
1379 return isStatic() ? ElementKind.STATIC_INIT : ElementKind.INSTANCE_INIT;
1380 else
1381 return ElementKind.METHOD;
1382 }
1384 public boolean isStaticOrInstanceInit() {
1385 return getKind() == ElementKind.STATIC_INIT ||
1386 getKind() == ElementKind.INSTANCE_INIT;
1387 }
1389 /**
1390 * A polymorphic signature method (JLS SE 7, 8.4.1) is a method that
1391 * (i) is declared in the java.lang.invoke.MethodHandle class, (ii) takes
1392 * a single variable arity parameter (iii) whose declared type is Object[],
1393 * (iv) has a return type of Object and (v) is native.
1394 */
1395 public boolean isSignaturePolymorphic(Types types) {
1396 List<Type> argtypes = type.getParameterTypes();
1397 Type firstElemType = argtypes.nonEmpty() ?
1398 types.elemtype(argtypes.head) :
1399 null;
1400 return owner == types.syms.methodHandleType.tsym &&
1401 argtypes.length() == 1 &&
1402 firstElemType != null &&
1403 types.isSameType(firstElemType, types.syms.objectType) &&
1404 types.isSameType(type.getReturnType(), types.syms.objectType) &&
1405 (flags() & NATIVE) != 0;
1406 }
1408 public Attribute getDefaultValue() {
1409 return defaultValue;
1410 }
1412 public List<VarSymbol> getParameters() {
1413 return params();
1414 }
1416 public boolean isVarArgs() {
1417 return (flags() & VARARGS) != 0;
1418 }
1420 public boolean isDefault() {
1421 return (flags() & DEFAULT) != 0;
1422 }
1424 public <R, P> R accept(ElementVisitor<R, P> v, P p) {
1425 return v.visitExecutable(this, p);
1426 }
1428 public <R, P> R accept(Symbol.Visitor<R, P> v, P p) {
1429 return v.visitMethodSymbol(this, p);
1430 }
1432 public Type getReturnType() {
1433 return asType().getReturnType();
1434 }
1436 public List<Type> getThrownTypes() {
1437 return asType().getThrownTypes();
1438 }
1439 }
1441 /** A class for invokedynamic method calls.
1442 */
1443 public static class DynamicMethodSymbol extends MethodSymbol {
1445 public Object[] staticArgs;
1446 public Symbol bsm;
1447 public int bsmKind;
1449 public DynamicMethodSymbol(Name name, Symbol owner, int bsmKind, MethodSymbol bsm, Type type, Object[] staticArgs) {
1450 super(0, name, type, owner);
1451 this.bsm = bsm;
1452 this.bsmKind = bsmKind;
1453 this.staticArgs = staticArgs;
1454 }
1456 @Override
1457 public boolean isDynamic() {
1458 return true;
1459 }
1460 }
1462 /** A class for predefined operators.
1463 */
1464 public static class OperatorSymbol extends MethodSymbol {
1466 public int opcode;
1468 public OperatorSymbol(Name name, Type type, int opcode, Symbol owner) {
1469 super(PUBLIC | STATIC, name, type, owner);
1470 this.opcode = opcode;
1471 }
1473 public <R, P> R accept(Symbol.Visitor<R, P> v, P p) {
1474 return v.visitOperatorSymbol(this, p);
1475 }
1476 }
1478 /** Symbol completer interface.
1479 */
1480 public static interface Completer {
1481 void complete(Symbol sym) throws CompletionFailure;
1482 }
1484 public static class CompletionFailure extends RuntimeException {
1485 private static final long serialVersionUID = 0;
1486 public Symbol sym;
1488 /** A diagnostic object describing the failure
1489 */
1490 public JCDiagnostic diag;
1492 /** A localized string describing the failure.
1493 * @deprecated Use {@code getDetail()} or {@code getMessage()}
1494 */
1495 @Deprecated
1496 public String errmsg;
1498 public CompletionFailure(Symbol sym, String errmsg) {
1499 this.sym = sym;
1500 this.errmsg = errmsg;
1501 // this.printStackTrace();//DEBUG
1502 }
1504 public CompletionFailure(Symbol sym, JCDiagnostic diag) {
1505 this.sym = sym;
1506 this.diag = diag;
1507 // this.printStackTrace();//DEBUG
1508 }
1510 public JCDiagnostic getDiagnostic() {
1511 return diag;
1512 }
1514 @Override
1515 public String getMessage() {
1516 if (diag != null)
1517 return diag.getMessage(null);
1518 else
1519 return errmsg;
1520 }
1522 public Object getDetailValue() {
1523 return (diag != null ? diag : errmsg);
1524 }
1526 @Override
1527 public CompletionFailure initCause(Throwable cause) {
1528 super.initCause(cause);
1529 return this;
1530 }
1532 }
1534 /**
1535 * A visitor for symbols. A visitor is used to implement operations
1536 * (or relations) on symbols. Most common operations on types are
1537 * binary relations and this interface is designed for binary
1538 * relations, that is, operations on the form
1539 * Symbol × P → R.
1540 * <!-- In plain text: Type x P -> R -->
1541 *
1542 * @param <R> the return type of the operation implemented by this
1543 * visitor; use Void if no return type is needed.
1544 * @param <P> the type of the second argument (the first being the
1545 * symbol itself) of the operation implemented by this visitor; use
1546 * Void if a second argument is not needed.
1547 */
1548 public interface Visitor<R,P> {
1549 R visitClassSymbol(ClassSymbol s, P arg);
1550 R visitMethodSymbol(MethodSymbol s, P arg);
1551 R visitPackageSymbol(PackageSymbol s, P arg);
1552 R visitOperatorSymbol(OperatorSymbol s, P arg);
1553 R visitVarSymbol(VarSymbol s, P arg);
1554 R visitTypeSymbol(TypeSymbol s, P arg);
1555 R visitSymbol(Symbol s, P arg);
1556 }
1557 }