Symtab.java revision 3323:680712ce0386
1138573Ssam/*
2138573Ssam * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
3138573Ssam * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4138573Ssam *
5138573Ssam * This code is free software; you can redistribute it and/or modify it
6138573Ssam * under the terms of the GNU General Public License version 2 only, as
7178354Ssam * published by the Free Software Foundation.  Oracle designates this
8138573Ssam * particular file as subject to the "Classpath" exception as provided
9178354Ssam * by Oracle in the LICENSE file that accompanied this code.
10178354Ssam *
11182668Simp * This code is distributed in the hope that it will be useful, but WITHOUT
12178354Ssam * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13178354Ssam * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14138573Ssam * 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 */
25
26package com.sun.tools.javac.code;
27
28import java.util.HashMap;
29import java.util.Map;
30
31import javax.lang.model.element.ElementVisitor;
32import javax.tools.JavaFileObject;
33
34
35import com.sun.tools.javac.code.Scope.WriteableScope;
36import com.sun.tools.javac.code.Symbol.ClassSymbol;
37import com.sun.tools.javac.code.Symbol.Completer;
38import com.sun.tools.javac.code.Symbol.CompletionFailure;
39import com.sun.tools.javac.code.Symbol.MethodSymbol;
40import com.sun.tools.javac.code.Symbol.PackageSymbol;
41import com.sun.tools.javac.code.Symbol.TypeSymbol;
42import com.sun.tools.javac.code.Symbol.VarSymbol;
43import com.sun.tools.javac.code.Type.BottomType;
44import com.sun.tools.javac.code.Type.ClassType;
45import com.sun.tools.javac.code.Type.ErrorType;
46import com.sun.tools.javac.code.Type.JCPrimitiveType;
47import com.sun.tools.javac.code.Type.JCVoidType;
48import com.sun.tools.javac.code.Type.MethodType;
49import com.sun.tools.javac.code.Type.UnknownType;
50import com.sun.tools.javac.jvm.Target;
51import com.sun.tools.javac.util.Assert;
52import com.sun.tools.javac.util.Context;
53import com.sun.tools.javac.util.Convert;
54import com.sun.tools.javac.util.DefinedBy;
55import com.sun.tools.javac.util.DefinedBy.Api;
56import com.sun.tools.javac.util.JavacMessages;
57import com.sun.tools.javac.util.List;
58import com.sun.tools.javac.util.Log;
59import com.sun.tools.javac.util.Name;
60import com.sun.tools.javac.util.Names;
61
62import static com.sun.tools.javac.code.Flags.*;
63import static com.sun.tools.javac.code.Kinds.Kind.*;
64import static com.sun.tools.javac.code.TypeTag.*;
65
66/** A class that defines all predefined constants and operators
67 *  as well as special classes such as java.lang.Object, which need
68 *  to be known to the compiler. All symbols are held in instance
69 *  fields. This makes it possible to work in multiple concurrent
70 *  projects, which might use different class files for library classes.
71 *
72 *  <p><b>This is NOT part of any supported API.
73 *  If you write code that depends on this, you do so at your own risk.
74 *  This code and its internal interfaces are subject to change or
75 *  deletion without notice.</b>
76 */
77public class Symtab {
78    /** The context key for the symbol table. */
79    protected static final Context.Key<Symtab> symtabKey = new Context.Key<>();
80
81    /** Get the symbol table instance. */
82    public static Symtab instance(Context context) {
83        Symtab instance = context.get(symtabKey);
84        if (instance == null)
85            instance = new Symtab(context);
86        return instance;
87    }
88
89    /** Builtin types.
90     */
91    public final JCPrimitiveType byteType = new JCPrimitiveType(BYTE, null);
92    public final JCPrimitiveType charType = new JCPrimitiveType(CHAR, null);
93    public final JCPrimitiveType shortType = new JCPrimitiveType(SHORT, null);
94    public final JCPrimitiveType intType = new JCPrimitiveType(INT, null);
95    public final JCPrimitiveType longType = new JCPrimitiveType(LONG, null);
96    public final JCPrimitiveType floatType = new JCPrimitiveType(FLOAT, null);
97    public final JCPrimitiveType doubleType = new JCPrimitiveType(DOUBLE, null);
98    public final JCPrimitiveType booleanType = new JCPrimitiveType(BOOLEAN, null);
99    public final Type botType = new BottomType();
100    public final JCVoidType voidType = new JCVoidType();
101
102    private final Names names;
103    private final Completer initialCompleter;
104    private final Target target;
105
106    /** A symbol for the root package.
107     */
108    public final PackageSymbol rootPackage;
109
110    /** A symbol for the unnamed package.
111     */
112    public final PackageSymbol unnamedPackage;
113
114    /** A symbol that stands for a missing symbol.
115     */
116    public final TypeSymbol noSymbol;
117
118    /** The error symbol.
119     */
120    public final ClassSymbol errSymbol;
121
122    /** The unknown symbol.
123     */
124    public final ClassSymbol unknownSymbol;
125
126    /** A value for the errType, with a originalType of noType */
127    public final Type errType;
128
129    /** A value for the unknown type. */
130    public final Type unknownType;
131
132    /** The builtin type of all arrays. */
133    public final ClassSymbol arrayClass;
134    public final MethodSymbol arrayCloneMethod;
135
136    /** VGJ: The (singleton) type of all bound types. */
137    public final ClassSymbol boundClass;
138
139    /** The builtin type of all methods. */
140    public final ClassSymbol methodClass;
141
142    /** Predefined types.
143     */
144    public final Type objectType;
145    public final Type objectsType;
146    public final Type classType;
147    public final Type classLoaderType;
148    public final Type stringType;
149    public final Type stringBufferType;
150    public final Type stringBuilderType;
151    public final Type cloneableType;
152    public final Type serializableType;
153    public final Type serializedLambdaType;
154    public final Type varHandleType;
155    public final Type methodHandleType;
156    public final Type methodHandleLookupType;
157    public final Type methodTypeType;
158    public final Type nativeHeaderType;
159    public final Type throwableType;
160    public final Type errorType;
161    public final Type interruptedExceptionType;
162    public final Type illegalArgumentExceptionType;
163    public final Type exceptionType;
164    public final Type runtimeExceptionType;
165    public final Type classNotFoundExceptionType;
166    public final Type noClassDefFoundErrorType;
167    public final Type noSuchFieldErrorType;
168    public final Type assertionErrorType;
169    public final Type cloneNotSupportedExceptionType;
170    public final Type annotationType;
171    public final TypeSymbol enumSym;
172    public final Type listType;
173    public final Type collectionsType;
174    public final Type comparableType;
175    public final Type comparatorType;
176    public final Type arraysType;
177    public final Type iterableType;
178    public final Type iteratorType;
179    public final Type annotationTargetType;
180    public final Type overrideType;
181    public final Type retentionType;
182    public final Type deprecatedType;
183    public final Type suppressWarningsType;
184    public final Type supplierType;
185    public final Type inheritedType;
186    public final Type profileType;
187    public final Type proprietaryType;
188    public final Type systemType;
189    public final Type autoCloseableType;
190    public final Type trustMeType;
191    public final Type lambdaMetafactory;
192    public final Type stringConcatFactory;
193    public final Type repeatableType;
194    public final Type documentedType;
195    public final Type elementTypeType;
196    public final Type functionalInterfaceType;
197
198    /** The symbol representing the length field of an array.
199     */
200    public final VarSymbol lengthVar;
201
202    /** The symbol representing the final finalize method on enums */
203    public final MethodSymbol enumFinalFinalize;
204
205    /** The symbol representing the close method on TWR AutoCloseable type */
206    public final MethodSymbol autoCloseableClose;
207
208    /** The predefined type that belongs to a tag.
209     */
210    public final Type[] typeOfTag = new Type[TypeTag.getTypeTagCount()];
211
212    /** The name of the class that belongs to a basix type tag.
213     */
214    public final Name[] boxedName = new Name[TypeTag.getTypeTagCount()];
215
216    /** A hashtable containing the encountered top-level and member classes,
217     *  indexed by flat names. The table does not contain local classes.
218     *  It should be updated from the outside to reflect classes defined
219     *  by compiled source files.
220     */
221    public final Map<Name, ClassSymbol> classes = new HashMap<>();
222
223    /** A hashtable containing the encountered packages.
224     *  the table should be updated from outside to reflect packages defined
225     *  by compiled source files.
226     */
227    public final Map<Name, PackageSymbol> packages = new HashMap<>();
228
229    public void initType(Type type, ClassSymbol c) {
230        type.tsym = c;
231        typeOfTag[type.getTag().ordinal()] = type;
232    }
233
234    public void initType(Type type, String name) {
235        initType(
236            type,
237            new ClassSymbol(
238                PUBLIC, names.fromString(name), type, rootPackage));
239    }
240
241    public void initType(Type type, String name, String bname) {
242        initType(type, name);
243            boxedName[type.getTag().ordinal()] = names.fromString("java.lang." + bname);
244    }
245
246    /** The class symbol that owns all predefined symbols.
247     */
248    public final ClassSymbol predefClass;
249
250    /** Enter a class into symbol table.
251     *  @param s The name of the class.
252     */
253    private Type enterClass(String s) {
254        return enterClass(names.fromString(s)).type;
255    }
256
257    public void synthesizeEmptyInterfaceIfMissing(final Type type) {
258        final Completer completer = type.tsym.completer;
259        type.tsym.completer = new Completer() {
260            public void complete(Symbol sym) throws CompletionFailure {
261                try {
262                    completer.complete(sym);
263                } catch (CompletionFailure e) {
264                    sym.flags_field |= (PUBLIC | INTERFACE);
265                    ((ClassType) sym.type).supertype_field = objectType;
266                }
267            }
268
269            @Override
270            public boolean isTerminal() {
271                return completer.isTerminal();
272            }
273        };
274    }
275
276    public void synthesizeBoxTypeIfMissing(final Type type) {
277        ClassSymbol sym = enterClass(boxedName[type.getTag().ordinal()]);
278        final Completer completer = sym.completer;
279        sym.completer = new Completer() {
280            public void complete(Symbol sym) throws CompletionFailure {
281                try {
282                    completer.complete(sym);
283                } catch (CompletionFailure e) {
284                    sym.flags_field |= PUBLIC;
285                    ((ClassType) sym.type).supertype_field = objectType;
286                    MethodSymbol boxMethod =
287                        new MethodSymbol(PUBLIC | STATIC, names.valueOf,
288                                         new MethodType(List.of(type), sym.type,
289                                List.<Type>nil(), methodClass),
290                            sym);
291                    sym.members().enter(boxMethod);
292                    MethodSymbol unboxMethod =
293                        new MethodSymbol(PUBLIC,
294                            type.tsym.name.append(names.Value), // x.intValue()
295                            new MethodType(List.<Type>nil(), type,
296                                List.<Type>nil(), methodClass),
297                            sym);
298                    sym.members().enter(unboxMethod);
299                }
300            }
301
302            @Override
303            public boolean isTerminal() {
304                return completer.isTerminal();
305            }
306        };
307    }
308
309    // Enter a synthetic class that is used to mark classes in ct.sym.
310    // This class does not have a class file.
311    private Type enterSyntheticAnnotation(String name) {
312        ClassType type = (ClassType)enterClass(name);
313        ClassSymbol sym = (ClassSymbol)type.tsym;
314        sym.completer = Completer.NULL_COMPLETER;
315        sym.flags_field = PUBLIC|ACYCLIC|ANNOTATION|INTERFACE;
316        sym.erasure_field = type;
317        sym.members_field = WriteableScope.create(sym);
318        type.typarams_field = List.nil();
319        type.allparams_field = List.nil();
320        type.supertype_field = annotationType;
321        type.interfaces_field = List.nil();
322        return type;
323    }
324
325    /** Constructor; enters all predefined identifiers and operators
326     *  into symbol table.
327     */
328    protected Symtab(Context context) throws CompletionFailure {
329        context.put(symtabKey, this);
330
331        names = Names.instance(context);
332        target = Target.instance(context);
333
334        // Create the unknown type
335        unknownType = new UnknownType();
336
337        // create the basic builtin symbols
338        rootPackage = new PackageSymbol(names.empty, null);
339        packages.put(names.empty, rootPackage);
340        final JavacMessages messages = JavacMessages.instance(context);
341        unnamedPackage = new PackageSymbol(names.empty, rootPackage) {
342                public String toString() {
343                    return messages.getLocalizedString("compiler.misc.unnamed.package");
344                }
345            };
346        noSymbol = new TypeSymbol(NIL, 0, names.empty, Type.noType, rootPackage) {
347            @DefinedBy(Api.LANGUAGE_MODEL)
348            public <R, P> R accept(ElementVisitor<R, P> v, P p) {
349                return v.visitUnknown(this, p);
350            }
351        };
352
353        // create the error symbols
354        errSymbol = new ClassSymbol(PUBLIC|STATIC|ACYCLIC, names.any, null, rootPackage);
355        errType = new ErrorType(errSymbol, Type.noType);
356
357        unknownSymbol = new ClassSymbol(PUBLIC|STATIC|ACYCLIC, names.fromString("<any?>"), null, rootPackage);
358        unknownSymbol.members_field = new Scope.ErrorScope(unknownSymbol);
359        unknownSymbol.type = unknownType;
360
361        // initialize builtin types
362        initType(byteType, "byte", "Byte");
363        initType(shortType, "short", "Short");
364        initType(charType, "char", "Character");
365        initType(intType, "int", "Integer");
366        initType(longType, "long", "Long");
367        initType(floatType, "float", "Float");
368        initType(doubleType, "double", "Double");
369        initType(booleanType, "boolean", "Boolean");
370        initType(voidType, "void", "Void");
371        initType(botType, "<nulltype>");
372        initType(errType, errSymbol);
373        initType(unknownType, unknownSymbol);
374
375        // the builtin class of all arrays
376        arrayClass = new ClassSymbol(PUBLIC|ACYCLIC, names.Array, noSymbol);
377
378        // VGJ
379        boundClass = new ClassSymbol(PUBLIC|ACYCLIC, names.Bound, noSymbol);
380        boundClass.members_field = new Scope.ErrorScope(boundClass);
381
382        // the builtin class of all methods
383        methodClass = new ClassSymbol(PUBLIC|ACYCLIC, names.Method, noSymbol);
384        methodClass.members_field = new Scope.ErrorScope(boundClass);
385
386        // Create class to hold all predefined constants and operations.
387        predefClass = new ClassSymbol(PUBLIC|ACYCLIC, names.empty, rootPackage);
388        WriteableScope scope = WriteableScope.create(predefClass);
389        predefClass.members_field = scope;
390
391        // Get the initial completer for Symbols from the ClassFinder
392        initialCompleter = ClassFinder.instance(context).getCompleter();
393        rootPackage.completer = initialCompleter;
394        unnamedPackage.completer = initialCompleter;
395
396        // Enter symbols for basic types.
397        scope.enter(byteType.tsym);
398        scope.enter(shortType.tsym);
399        scope.enter(charType.tsym);
400        scope.enter(intType.tsym);
401        scope.enter(longType.tsym);
402        scope.enter(floatType.tsym);
403        scope.enter(doubleType.tsym);
404        scope.enter(booleanType.tsym);
405        scope.enter(errType.tsym);
406
407        // Enter symbol for the errSymbol
408        scope.enter(errSymbol);
409
410        classes.put(predefClass.fullname, predefClass);
411
412        // Enter predefined classes.
413        objectType = enterClass("java.lang.Object");
414        objectsType = enterClass("java.util.Objects");
415        classType = enterClass("java.lang.Class");
416        stringType = enterClass("java.lang.String");
417        stringBufferType = enterClass("java.lang.StringBuffer");
418        stringBuilderType = enterClass("java.lang.StringBuilder");
419        cloneableType = enterClass("java.lang.Cloneable");
420        throwableType = enterClass("java.lang.Throwable");
421        serializableType = enterClass("java.io.Serializable");
422        serializedLambdaType = enterClass("java.lang.invoke.SerializedLambda");
423        varHandleType = enterClass("java.lang.invoke.VarHandle");
424        methodHandleType = enterClass("java.lang.invoke.MethodHandle");
425        methodHandleLookupType = enterClass("java.lang.invoke.MethodHandles$Lookup");
426        methodTypeType = enterClass("java.lang.invoke.MethodType");
427        errorType = enterClass("java.lang.Error");
428        illegalArgumentExceptionType = enterClass("java.lang.IllegalArgumentException");
429        interruptedExceptionType = enterClass("java.lang.InterruptedException");
430        exceptionType = enterClass("java.lang.Exception");
431        runtimeExceptionType = enterClass("java.lang.RuntimeException");
432        classNotFoundExceptionType = enterClass("java.lang.ClassNotFoundException");
433        noClassDefFoundErrorType = enterClass("java.lang.NoClassDefFoundError");
434        noSuchFieldErrorType = enterClass("java.lang.NoSuchFieldError");
435        assertionErrorType = enterClass("java.lang.AssertionError");
436        cloneNotSupportedExceptionType = enterClass("java.lang.CloneNotSupportedException");
437        annotationType = enterClass("java.lang.annotation.Annotation");
438        classLoaderType = enterClass("java.lang.ClassLoader");
439        enumSym = enterClass(names.java_lang_Enum);
440        enumFinalFinalize =
441            new MethodSymbol(PROTECTED|FINAL|HYPOTHETICAL,
442                             names.finalize,
443                             new MethodType(List.<Type>nil(), voidType,
444                                            List.<Type>nil(), methodClass),
445                             enumSym);
446        listType = enterClass("java.util.List");
447        collectionsType = enterClass("java.util.Collections");
448        comparableType = enterClass("java.lang.Comparable");
449        comparatorType = enterClass("java.util.Comparator");
450        arraysType = enterClass("java.util.Arrays");
451        iterableType = enterClass("java.lang.Iterable");
452        iteratorType = enterClass("java.util.Iterator");
453        annotationTargetType = enterClass("java.lang.annotation.Target");
454        overrideType = enterClass("java.lang.Override");
455        retentionType = enterClass("java.lang.annotation.Retention");
456        deprecatedType = enterClass("java.lang.Deprecated");
457        suppressWarningsType = enterClass("java.lang.SuppressWarnings");
458        supplierType = enterClass("java.util.function.Supplier");
459        inheritedType = enterClass("java.lang.annotation.Inherited");
460        repeatableType = enterClass("java.lang.annotation.Repeatable");
461        documentedType = enterClass("java.lang.annotation.Documented");
462        elementTypeType = enterClass("java.lang.annotation.ElementType");
463        systemType = enterClass("java.lang.System");
464        autoCloseableType = enterClass("java.lang.AutoCloseable");
465        autoCloseableClose = new MethodSymbol(PUBLIC,
466                             names.close,
467                             new MethodType(List.<Type>nil(), voidType,
468                                            List.of(exceptionType), methodClass),
469                             autoCloseableType.tsym);
470        trustMeType = enterClass("java.lang.SafeVarargs");
471        nativeHeaderType = enterClass("java.lang.annotation.Native");
472        lambdaMetafactory = enterClass("java.lang.invoke.LambdaMetafactory");
473        stringConcatFactory = enterClass("java.lang.invoke.StringConcatFactory");
474        functionalInterfaceType = enterClass("java.lang.FunctionalInterface");
475
476        synthesizeEmptyInterfaceIfMissing(autoCloseableType);
477        synthesizeEmptyInterfaceIfMissing(cloneableType);
478        synthesizeEmptyInterfaceIfMissing(serializableType);
479        synthesizeEmptyInterfaceIfMissing(lambdaMetafactory);
480        synthesizeEmptyInterfaceIfMissing(serializedLambdaType);
481        synthesizeEmptyInterfaceIfMissing(stringConcatFactory);
482        synthesizeBoxTypeIfMissing(doubleType);
483        synthesizeBoxTypeIfMissing(floatType);
484        synthesizeBoxTypeIfMissing(voidType);
485
486        // Enter a synthetic class that is used to mark internal
487        // proprietary classes in ct.sym.  This class does not have a
488        // class file.
489        proprietaryType = enterSyntheticAnnotation("sun.Proprietary+Annotation");
490
491        // Enter a synthetic class that is used to provide profile info for
492        // classes in ct.sym.  This class does not have a class file.
493        profileType = enterSyntheticAnnotation("jdk.Profile+Annotation");
494        MethodSymbol m = new MethodSymbol(PUBLIC | ABSTRACT, names.value, intType, profileType.tsym);
495        profileType.tsym.members().enter(m);
496
497        // Enter a class for arrays.
498        // The class implements java.lang.Cloneable and java.io.Serializable.
499        // It has a final length field and a clone method.
500        ClassType arrayClassType = (ClassType)arrayClass.type;
501        arrayClassType.supertype_field = objectType;
502        arrayClassType.interfaces_field = List.of(cloneableType, serializableType);
503        arrayClass.members_field = WriteableScope.create(arrayClass);
504        lengthVar = new VarSymbol(
505            PUBLIC | FINAL,
506            names.length,
507            intType,
508            arrayClass);
509        arrayClass.members().enter(lengthVar);
510        arrayCloneMethod = new MethodSymbol(
511            PUBLIC,
512            names.clone,
513            new MethodType(List.<Type>nil(), objectType,
514                           List.<Type>nil(), methodClass),
515            arrayClass);
516        arrayClass.members().enter(arrayCloneMethod);
517    }
518
519    /** Define a new class given its name and owner.
520     */
521    public ClassSymbol defineClass(Name name, Symbol owner) {
522        ClassSymbol c = new ClassSymbol(0, name, owner);
523        if (owner.kind == PCK)
524            Assert.checkNull(classes.get(c.flatname), c);
525        c.completer = initialCompleter;
526        return c;
527    }
528
529    /** Create a new toplevel or member class symbol with given name
530     *  and owner and enter in `classes' unless already there.
531     */
532    public ClassSymbol enterClass(Name name, TypeSymbol owner) {
533        Name flatname = TypeSymbol.formFlatName(name, owner);
534        ClassSymbol c = classes.get(flatname);
535        if (c == null) {
536            c = defineClass(name, owner);
537            classes.put(flatname, c);
538        } else if ((c.name != name || c.owner != owner) && owner.kind == TYP && c.owner.kind == PCK) {
539            // reassign fields of classes that might have been loaded with
540            // their flat names.
541            c.owner.members().remove(c);
542            c.name = name;
543            c.owner = owner;
544            c.fullname = ClassSymbol.formFullName(name, owner);
545        }
546        return c;
547    }
548
549    /**
550     * Creates a new toplevel class symbol with given flat name and
551     * given class (or source) file.
552     *
553     * @param flatName a fully qualified binary class name
554     * @param classFile the class file or compilation unit defining
555     * the class (may be {@code null})
556     * @return a newly created class symbol
557     * @throws AssertionError if the class symbol already exists
558     */
559    public ClassSymbol enterClass(Name flatName, JavaFileObject classFile) {
560        ClassSymbol cs = classes.get(flatName);
561        if (cs != null) {
562            String msg = Log.format("%s: completer = %s; class file = %s; source file = %s",
563                                    cs.fullname,
564                                    cs.completer,
565                                    cs.classfile,
566                                    cs.sourcefile);
567            throw new AssertionError(msg);
568        }
569        Name packageName = Convert.packagePart(flatName);
570        PackageSymbol owner = packageName.isEmpty()
571                                ? unnamedPackage
572                                : enterPackage(packageName);
573        cs = defineClass(Convert.shortName(flatName), owner);
574        cs.classfile = classFile;
575        classes.put(flatName, cs);
576        return cs;
577    }
578
579    /** Create a new member or toplevel class symbol with given flat name
580     *  and enter in `classes' unless already there.
581     */
582    public ClassSymbol enterClass(Name flatname) {
583        ClassSymbol c = classes.get(flatname);
584        if (c == null)
585            return enterClass(flatname, (JavaFileObject)null);
586        else
587            return c;
588    }
589
590    /** Check to see if a package exists, given its fully qualified name.
591     */
592    public boolean packageExists(Name fullname) {
593        return enterPackage(fullname).exists();
594    }
595
596    /** Make a package, given its fully qualified name.
597     */
598    public PackageSymbol enterPackage(Name fullname) {
599        PackageSymbol p = packages.get(fullname);
600        if (p == null) {
601            Assert.check(!fullname.isEmpty(), "rootPackage missing!");
602            p = new PackageSymbol(
603                Convert.shortName(fullname),
604                enterPackage(Convert.packagePart(fullname)));
605            p.completer = initialCompleter;
606            packages.put(fullname, p);
607        }
608        return p;
609    }
610
611    /** Make a package, given its unqualified name and enclosing package.
612     */
613    public PackageSymbol enterPackage(Name name, PackageSymbol owner) {
614        return enterPackage(TypeSymbol.formFullName(name, owner));
615    }
616}
617