JavacElements.java revision 3824:376ee1fd40c3
1/*
2 * Copyright (c) 2005, 2016, 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 */
25
26package com.sun.tools.javac.model;
27
28import java.util.LinkedHashSet;
29import java.util.Map;
30import java.util.Set;
31
32import javax.lang.model.SourceVersion;
33import javax.lang.model.element.*;
34import javax.lang.model.type.DeclaredType;
35import javax.lang.model.util.Elements;
36import javax.tools.JavaFileObject;
37import static javax.lang.model.util.ElementFilter.methodsIn;
38
39import com.sun.source.util.JavacTask;
40import com.sun.tools.javac.api.JavacTaskImpl;
41import com.sun.tools.javac.code.*;
42import com.sun.tools.javac.code.Scope.WriteableScope;
43import com.sun.tools.javac.code.Symbol.*;
44import com.sun.tools.javac.comp.AttrContext;
45import com.sun.tools.javac.comp.Enter;
46import com.sun.tools.javac.comp.Env;
47import com.sun.tools.javac.main.JavaCompiler;
48import com.sun.tools.javac.processing.PrintingProcessor;
49import com.sun.tools.javac.tree.JCTree;
50import com.sun.tools.javac.tree.JCTree.*;
51import com.sun.tools.javac.tree.TreeInfo;
52import com.sun.tools.javac.tree.TreeScanner;
53import com.sun.tools.javac.util.*;
54import com.sun.tools.javac.util.DefinedBy.Api;
55import com.sun.tools.javac.util.Name;
56import static com.sun.tools.javac.code.Kinds.Kind.*;
57import static com.sun.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;
58import static com.sun.tools.javac.code.TypeTag.CLASS;
59import com.sun.tools.javac.comp.Modules;
60import com.sun.tools.javac.comp.Resolve;
61import com.sun.tools.javac.comp.Resolve.RecoveryLoadClass;
62import static com.sun.tools.javac.tree.JCTree.Tag.*;
63
64/**
65 * Utility methods for operating on program elements.
66 *
67 * <p><b>This is NOT part of any supported API.
68 * If you write code that depends on this, you do so at your own
69 * risk.  This code and its internal interfaces are subject to change
70 * or deletion without notice.</b></p>
71 */
72public class JavacElements implements Elements {
73
74    private final JavaCompiler javaCompiler;
75    private final Symtab syms;
76    private final Modules modules;
77    private final Names names;
78    private final Types types;
79    private final Enter enter;
80    private final Resolve resolve;
81    private final JavacTaskImpl javacTaskImpl;
82
83    public static JavacElements instance(Context context) {
84        JavacElements instance = context.get(JavacElements.class);
85        if (instance == null)
86            instance = new JavacElements(context);
87        return instance;
88    }
89
90    protected JavacElements(Context context) {
91        context.put(JavacElements.class, this);
92        javaCompiler = JavaCompiler.instance(context);
93        syms = Symtab.instance(context);
94        modules = Modules.instance(context);
95        names = Names.instance(context);
96        types = Types.instance(context);
97        enter = Enter.instance(context);
98        resolve = Resolve.instance(context);
99        JavacTask t = context.get(JavacTask.class);
100        javacTaskImpl = t instanceof JavacTaskImpl ? (JavacTaskImpl) t : null;
101    }
102
103    @Override @DefinedBy(Api.LANGUAGE_MODEL)
104    public ModuleSymbol getModuleElement(CharSequence name) {
105        ensureEntered("getModuleElement");
106        if (modules.getDefaultModule() == syms.noModule)
107            return null;
108        String strName = name.toString();
109        if (strName.equals(""))
110            return syms.unnamedModule;
111        return modules.getObservableModule(names.fromString(strName));
112    }
113
114    @Override @DefinedBy(Api.LANGUAGE_MODEL)
115    public PackageSymbol getPackageElement(CharSequence name) {
116        return doGetPackageElement(null, name);
117    }
118
119    @Override @DefinedBy(Api.LANGUAGE_MODEL)
120    public PackageSymbol getPackageElement(ModuleElement module, CharSequence name) {
121        module.getClass();
122        return doGetPackageElement(module, name);
123    }
124
125    private PackageSymbol doGetPackageElement(ModuleElement module, CharSequence name) {
126        ensureEntered("getPackageElement");
127        if (name.length() == 0)
128            return syms.unnamedModule.unnamedPackage;
129        return doGetElement(module, name, PackageSymbol.class);
130    }
131
132    @Override @DefinedBy(Api.LANGUAGE_MODEL)
133    public ClassSymbol getTypeElement(CharSequence name) {
134        return doGetTypeElement(null, name);
135    }
136
137    @Override @DefinedBy(Api.LANGUAGE_MODEL)
138    public ClassSymbol getTypeElement(ModuleElement module, CharSequence name) {
139        module.getClass();
140
141        return doGetTypeElement(module, name);
142    }
143
144    private ClassSymbol doGetTypeElement(ModuleElement module, CharSequence name) {
145        ensureEntered("getTypeElement");
146        return doGetElement(module, name, ClassSymbol.class);
147    }
148
149    private <S extends Symbol> S doGetElement(ModuleElement module, CharSequence name, Class<S> clazz) {
150        String strName = name.toString();
151        if (!SourceVersion.isName(strName)) {
152            return null;
153        }
154        if (module == null) {
155            return unboundNameToSymbol(strName, clazz);
156        } else {
157            return nameToSymbol((ModuleSymbol) module, strName, clazz);
158        }
159    }
160
161    private <S extends Symbol> S unboundNameToSymbol(String nameStr, Class<S> clazz) {
162        if (modules.getDefaultModule() == syms.noModule) { //not a modular mode:
163            return nameToSymbol(syms.noModule, nameStr, clazz);
164        }
165
166        RecoveryLoadClass prevRecoveryLoadClass = resolve.setRecoveryLoadClass((env, name) -> null);
167        try {
168            Set<S> found = new LinkedHashSet<>();
169
170            for (ModuleSymbol msym : modules.allModules()) {
171                S sym = nameToSymbol(msym, nameStr, clazz);
172
173                if (sym != null) {
174                    found.add(sym);
175                }
176            }
177
178            if (found.size() == 1) {
179                return found.iterator().next();
180            } else {
181                //not found, or more than one element found:
182                return null;
183            }
184        } finally {
185            resolve.setRecoveryLoadClass(prevRecoveryLoadClass);
186        }
187    }
188
189    /**
190     * Returns a symbol given the type's or package's canonical name,
191     * or null if the name isn't found.
192     */
193    private <S extends Symbol> S nameToSymbol(ModuleSymbol module, String nameStr, Class<S> clazz) {
194        Name name = names.fromString(nameStr);
195        // First check cache.
196        Symbol sym = (clazz == ClassSymbol.class)
197                    ? syms.getClass(module, name)
198                    : syms.lookupPackage(module, name);
199
200        try {
201            if (sym == null)
202                sym = javaCompiler.resolveIdent(module, nameStr);
203
204            sym.complete();
205
206            return (sym.kind != ERR &&
207                    sym.exists() &&
208                    clazz.isInstance(sym) &&
209                    name.equals(sym.getQualifiedName()))
210                ? clazz.cast(sym)
211                : null;
212        } catch (CompletionFailure e) {
213            return null;
214        }
215    }
216
217    public JavacSourcePosition getSourcePosition(Element e) {
218        Pair<JCTree, JCCompilationUnit> treeTop = getTreeAndTopLevel(e);
219        if (treeTop == null)
220            return null;
221        JCTree tree = treeTop.fst;
222        JCCompilationUnit toplevel = treeTop.snd;
223        JavaFileObject sourcefile = toplevel.sourcefile;
224        if (sourcefile == null)
225            return null;
226        return new JavacSourcePosition(sourcefile, tree.pos, toplevel.lineMap);
227    }
228
229    public JavacSourcePosition getSourcePosition(Element e, AnnotationMirror a) {
230        Pair<JCTree, JCCompilationUnit> treeTop = getTreeAndTopLevel(e);
231        if (treeTop == null)
232            return null;
233        JCTree tree = treeTop.fst;
234        JCCompilationUnit toplevel = treeTop.snd;
235        JavaFileObject sourcefile = toplevel.sourcefile;
236        if (sourcefile == null)
237            return null;
238
239        JCTree annoTree = matchAnnoToTree(a, e, tree);
240        if (annoTree == null)
241            return null;
242        return new JavacSourcePosition(sourcefile, annoTree.pos,
243                                       toplevel.lineMap);
244    }
245
246    public JavacSourcePosition getSourcePosition(Element e, AnnotationMirror a,
247                                            AnnotationValue v) {
248        // TODO: better accuracy in getSourcePosition(... AnnotationValue)
249        return getSourcePosition(e, a);
250    }
251
252    /**
253     * Returns the tree for an annotation given the annotated element
254     * and the element's own tree.  Returns null if the tree cannot be found.
255     */
256    private JCTree matchAnnoToTree(AnnotationMirror findme,
257                                   Element e, JCTree tree) {
258        Symbol sym = cast(Symbol.class, e);
259        class Vis extends JCTree.Visitor {
260            List<JCAnnotation> result = null;
261            public void visitPackageDef(JCPackageDecl tree) {
262                result = tree.annotations;
263            }
264            public void visitClassDef(JCClassDecl tree) {
265                result = tree.mods.annotations;
266            }
267            public void visitMethodDef(JCMethodDecl tree) {
268                result = tree.mods.annotations;
269            }
270            public void visitVarDef(JCVariableDecl tree) {
271                result = tree.mods.annotations;
272            }
273            @Override
274            public void visitTypeParameter(JCTypeParameter tree) {
275                result = tree.annotations;
276            }
277        }
278        Vis vis = new Vis();
279        tree.accept(vis);
280        if (vis.result == null)
281            return null;
282
283        List<Attribute.Compound> annos = sym.getAnnotationMirrors();
284        return matchAnnoToTree(cast(Attribute.Compound.class, findme),
285                               annos,
286                               vis.result);
287    }
288
289    /**
290     * Returns the tree for an annotation given a list of annotations
291     * in which to search (recursively) and their corresponding trees.
292     * Returns null if the tree cannot be found.
293     */
294    private JCTree matchAnnoToTree(Attribute.Compound findme,
295                                   List<Attribute.Compound> annos,
296                                   List<JCAnnotation> trees) {
297        for (Attribute.Compound anno : annos) {
298            for (JCAnnotation tree : trees) {
299                JCTree match = matchAnnoToTree(findme, anno, tree);
300                if (match != null)
301                    return match;
302            }
303        }
304        return null;
305    }
306
307    /**
308     * Returns the tree for an annotation given an Attribute to
309     * search (recursively) and its corresponding tree.
310     * Returns null if the tree cannot be found.
311     */
312    private JCTree matchAnnoToTree(final Attribute.Compound findme,
313                                   final Attribute attr,
314                                   final JCTree tree) {
315        if (attr == findme)
316            return (tree.type.tsym == findme.type.tsym) ? tree : null;
317
318        class Vis implements Attribute.Visitor {
319            JCTree result = null;
320            public void visitConstant(Attribute.Constant value) {
321            }
322            public void visitClass(Attribute.Class clazz) {
323            }
324            public void visitCompound(Attribute.Compound anno) {
325                for (Pair<MethodSymbol, Attribute> pair : anno.values) {
326                    JCExpression expr = scanForAssign(pair.fst, tree);
327                    if (expr != null) {
328                        JCTree match = matchAnnoToTree(findme, pair.snd, expr);
329                        if (match != null) {
330                            result = match;
331                            return;
332                        }
333                    }
334                }
335            }
336            public void visitArray(Attribute.Array array) {
337                if (tree.hasTag(NEWARRAY) &&
338                        types.elemtype(array.type).tsym == findme.type.tsym) {
339                    List<JCExpression> elems = ((JCNewArray) tree).elems;
340                    for (Attribute value : array.values) {
341                        if (value == findme) {
342                            result = elems.head;
343                            return;
344                        }
345                        elems = elems.tail;
346                    }
347                }
348            }
349            public void visitEnum(Attribute.Enum e) {
350            }
351            public void visitError(Attribute.Error e) {
352            }
353        }
354        Vis vis = new Vis();
355        attr.accept(vis);
356        return vis.result;
357    }
358
359    /**
360     * Scans for a JCAssign node with a LHS matching a given
361     * symbol, and returns its RHS.  Does not scan nested JCAnnotations.
362     */
363    private JCExpression scanForAssign(final MethodSymbol sym,
364                                       final JCTree tree) {
365        class TS extends TreeScanner {
366            JCExpression result = null;
367            public void scan(JCTree t) {
368                if (t != null && result == null)
369                    t.accept(this);
370            }
371            public void visitAnnotation(JCAnnotation t) {
372                if (t == tree)
373                    scan(t.args);
374            }
375            public void visitAssign(JCAssign t) {
376                if (t.lhs.hasTag(IDENT)) {
377                    JCIdent ident = (JCIdent) t.lhs;
378                    if (ident.sym == sym)
379                        result = t.rhs;
380                }
381            }
382        }
383        TS scanner = new TS();
384        tree.accept(scanner);
385        return scanner.result;
386    }
387
388    /**
389     * Returns the tree node corresponding to this element, or null
390     * if none can be found.
391     */
392    public JCTree getTree(Element e) {
393        Pair<JCTree, ?> treeTop = getTreeAndTopLevel(e);
394        return (treeTop != null) ? treeTop.fst : null;
395    }
396
397    @DefinedBy(Api.LANGUAGE_MODEL)
398    public String getDocComment(Element e) {
399        // Our doc comment is contained in a map in our toplevel,
400        // indexed by our tree.  Find our enter environment, which gives
401        // us our toplevel.  It also gives us a tree that contains our
402        // tree:  walk it to find our tree.  This is painful.
403        Pair<JCTree, JCCompilationUnit> treeTop = getTreeAndTopLevel(e);
404        if (treeTop == null)
405            return null;
406        JCTree tree = treeTop.fst;
407        JCCompilationUnit toplevel = treeTop.snd;
408        if (toplevel.docComments == null)
409            return null;
410        return toplevel.docComments.getCommentText(tree);
411    }
412
413    @DefinedBy(Api.LANGUAGE_MODEL)
414    public PackageElement getPackageOf(Element e) {
415        return cast(Symbol.class, e).packge();
416    }
417
418    @DefinedBy(Api.LANGUAGE_MODEL)
419    public ModuleElement getModuleOf(Element e) {
420        Symbol sym = cast(Symbol.class, e);
421        if (modules.getDefaultModule() == syms.noModule)
422            return null;
423        return (sym.kind == MDL) ? ((ModuleElement) e) : sym.packge().modle;
424    }
425
426    @DefinedBy(Api.LANGUAGE_MODEL)
427    public boolean isDeprecated(Element e) {
428        Symbol sym = cast(Symbol.class, e);
429        sym.complete();
430        return sym.isDeprecated();
431    }
432
433    @DefinedBy(Api.LANGUAGE_MODEL)
434    public Name getBinaryName(TypeElement type) {
435        return cast(TypeSymbol.class, type).flatName();
436    }
437
438    @DefinedBy(Api.LANGUAGE_MODEL)
439    public Map<MethodSymbol, Attribute> getElementValuesWithDefaults(
440                                                        AnnotationMirror a) {
441        Attribute.Compound anno = cast(Attribute.Compound.class, a);
442        DeclaredType annotype = a.getAnnotationType();
443        Map<MethodSymbol, Attribute> valmap = anno.getElementValues();
444
445        for (ExecutableElement ex :
446                 methodsIn(annotype.asElement().getEnclosedElements())) {
447            MethodSymbol meth = (MethodSymbol) ex;
448            Attribute defaultValue = meth.getDefaultValue();
449            if (defaultValue != null && !valmap.containsKey(meth)) {
450                valmap.put(meth, defaultValue);
451            }
452        }
453        return valmap;
454    }
455
456    /**
457     * {@inheritDoc}
458     */
459    @DefinedBy(Api.LANGUAGE_MODEL)
460    public FilteredMemberList getAllMembers(TypeElement element) {
461        Symbol sym = cast(Symbol.class, element);
462        WriteableScope scope = sym.members().dupUnshared();
463        List<Type> closure = types.closure(sym.asType());
464        for (Type t : closure)
465            addMembers(scope, t);
466        return new FilteredMemberList(scope);
467    }
468    // where
469        private void addMembers(WriteableScope scope, Type type) {
470            members:
471            for (Symbol e : type.asElement().members().getSymbols(NON_RECURSIVE)) {
472                for (Symbol overrider : scope.getSymbolsByName(e.getSimpleName())) {
473                    if (overrider.kind == e.kind && (overrider.flags() & Flags.SYNTHETIC) == 0) {
474                        if (overrider.getKind() == ElementKind.METHOD &&
475                                overrides((ExecutableElement)overrider, (ExecutableElement)e, (TypeElement)type.asElement())) {
476                            continue members;
477                        }
478                    }
479                }
480                boolean derived = e.getEnclosingElement() != scope.owner;
481                ElementKind kind = e.getKind();
482                boolean initializer = kind == ElementKind.CONSTRUCTOR
483                    || kind == ElementKind.INSTANCE_INIT
484                    || kind == ElementKind.STATIC_INIT;
485                if (!derived || (!initializer && e.isInheritedIn(scope.owner, types)))
486                    scope.enter(e);
487            }
488        }
489
490    /**
491     * Returns all annotations of an element, whether
492     * inherited or directly present.
493     *
494     * @param e  the element being examined
495     * @return all annotations of the element
496     */
497    @Override @DefinedBy(Api.LANGUAGE_MODEL)
498    public List<Attribute.Compound> getAllAnnotationMirrors(Element e) {
499        Symbol sym = cast(Symbol.class, e);
500        List<Attribute.Compound> annos = sym.getAnnotationMirrors();
501        while (sym.getKind() == ElementKind.CLASS) {
502            Type sup = ((ClassSymbol) sym).getSuperclass();
503            if (!sup.hasTag(CLASS) || sup.isErroneous() ||
504                    sup.tsym == syms.objectType.tsym) {
505                break;
506            }
507            sym = sup.tsym;
508            List<Attribute.Compound> oldAnnos = annos;
509            List<Attribute.Compound> newAnnos = sym.getAnnotationMirrors();
510            for (Attribute.Compound anno : newAnnos) {
511                if (isInherited(anno.type) &&
512                        !containsAnnoOfType(oldAnnos, anno.type)) {
513                    annos = annos.prepend(anno);
514                }
515            }
516        }
517        return annos;
518    }
519
520    /**
521     * Tests whether an annotation type is @Inherited.
522     */
523    private boolean isInherited(Type annotype) {
524        return annotype.tsym.attribute(syms.inheritedType.tsym) != null;
525    }
526
527    /**
528     * Tests whether a list of annotations contains an annotation
529     * of a given type.
530     */
531    private static boolean containsAnnoOfType(List<Attribute.Compound> annos,
532                                              Type type) {
533        for (Attribute.Compound anno : annos) {
534            if (anno.type.tsym == type.tsym)
535                return true;
536        }
537        return false;
538    }
539
540    @DefinedBy(Api.LANGUAGE_MODEL)
541    public boolean hides(Element hiderEl, Element hideeEl) {
542        Symbol hider = cast(Symbol.class, hiderEl);
543        Symbol hidee = cast(Symbol.class, hideeEl);
544
545        // Fields only hide fields; methods only methods; types only types.
546        // Names must match.  Nothing hides itself (just try it).
547        if (hider == hidee ||
548                hider.kind != hidee.kind ||
549                hider.name != hidee.name) {
550            return false;
551        }
552
553        // Only static methods can hide other methods.
554        // Methods only hide methods with matching signatures.
555        if (hider.kind == MTH) {
556            if (!hider.isStatic() ||
557                        !types.isSubSignature(hider.type, hidee.type)) {
558                return false;
559            }
560        }
561
562        // Hider must be in a subclass of hidee's class.
563        // Note that if M1 hides M2, and M2 hides M3, and M3 is accessible
564        // in M1's class, then M1 and M2 both hide M3.
565        ClassSymbol hiderClass = hider.owner.enclClass();
566        ClassSymbol hideeClass = hidee.owner.enclClass();
567        if (hiderClass == null || hideeClass == null ||
568                !hiderClass.isSubClass(hideeClass, types)) {
569            return false;
570        }
571
572        // Hidee must be accessible in hider's class.
573        // The method isInheritedIn is poorly named:  it checks only access.
574        return hidee.isInheritedIn(hiderClass, types);
575    }
576
577    @DefinedBy(Api.LANGUAGE_MODEL)
578    public boolean overrides(ExecutableElement riderEl,
579                             ExecutableElement rideeEl, TypeElement typeEl) {
580        MethodSymbol rider = cast(MethodSymbol.class, riderEl);
581        MethodSymbol ridee = cast(MethodSymbol.class, rideeEl);
582        ClassSymbol origin = cast(ClassSymbol.class, typeEl);
583
584        return rider.name == ridee.name &&
585
586               // not reflexive as per JLS
587               rider != ridee &&
588
589               // we don't care if ridee is static, though that wouldn't
590               // compile
591               !rider.isStatic() &&
592
593               // Symbol.overrides assumes the following
594               ridee.isMemberOf(origin, types) &&
595
596               // check access and signatures; don't check return types
597               rider.overrides(ridee, origin, types, false);
598    }
599
600    @DefinedBy(Api.LANGUAGE_MODEL)
601    public String getConstantExpression(Object value) {
602        return Constants.format(value);
603    }
604
605    /**
606     * Print a representation of the elements to the given writer in
607     * the specified order.  The main purpose of this method is for
608     * diagnostics.  The exact format of the output is <em>not</em>
609     * specified and is subject to change.
610     *
611     * @param w the writer to print the output to
612     * @param elements the elements to print
613     */
614    @DefinedBy(Api.LANGUAGE_MODEL)
615    public void printElements(java.io.Writer w, Element... elements) {
616        for (Element element : elements)
617            (new PrintingProcessor.PrintingElementVisitor(w, this)).visit(element).flush();
618    }
619
620    @DefinedBy(Api.LANGUAGE_MODEL)
621    public Name getName(CharSequence cs) {
622        return names.fromString(cs.toString());
623    }
624
625    @Override @DefinedBy(Api.LANGUAGE_MODEL)
626    public boolean isFunctionalInterface(TypeElement element) {
627        if (element.getKind() != ElementKind.INTERFACE)
628            return false;
629        else {
630            TypeSymbol tsym = cast(TypeSymbol.class, element);
631            return types.isFunctionalInterface(tsym);
632        }
633    }
634
635    /**
636     * Returns the tree node and compilation unit corresponding to this
637     * element, or null if they can't be found.
638     */
639    private Pair<JCTree, JCCompilationUnit> getTreeAndTopLevel(Element e) {
640        Symbol sym = cast(Symbol.class, e);
641        Env<AttrContext> enterEnv = getEnterEnv(sym);
642        if (enterEnv == null)
643            return null;
644        JCTree tree = TreeInfo.declarationFor(sym, enterEnv.tree);
645        if (tree == null || enterEnv.toplevel == null)
646            return null;
647        return new Pair<>(tree, enterEnv.toplevel);
648    }
649
650    /**
651     * Returns the best approximation for the tree node and compilation unit
652     * corresponding to the given element, annotation and value.
653     * If the element is null, null is returned.
654     * If the annotation is null or cannot be found, the tree node and
655     * compilation unit for the element is returned.
656     * If the annotation value is null or cannot be found, the tree node and
657     * compilation unit for the annotation is returned.
658     */
659    public Pair<JCTree, JCCompilationUnit> getTreeAndTopLevel(
660                      Element e, AnnotationMirror a, AnnotationValue v) {
661        if (e == null)
662            return null;
663
664        Pair<JCTree, JCCompilationUnit> elemTreeTop = getTreeAndTopLevel(e);
665        if (elemTreeTop == null)
666            return null;
667
668        if (a == null)
669            return elemTreeTop;
670
671        JCTree annoTree = matchAnnoToTree(a, e, elemTreeTop.fst);
672        if (annoTree == null)
673            return elemTreeTop;
674
675        // 6388543: if v != null, we should search within annoTree to find
676        // the tree matching v. For now, we ignore v and return the tree of
677        // the annotation.
678        return new Pair<>(annoTree, elemTreeTop.snd);
679    }
680
681    /**
682     * Returns a symbol's enter environment, or null if it has none.
683     */
684    private Env<AttrContext> getEnterEnv(Symbol sym) {
685        // Get enclosing class of sym, or sym itself if it is a class
686        // package, or module.
687        TypeSymbol ts = null;
688        switch (sym.kind) {
689            case PCK:
690                ts = (PackageSymbol)sym;
691                break;
692            case MDL:
693                ts = (ModuleSymbol)sym;
694                break;
695            default:
696                ts = sym.enclClass();
697        }
698        return (ts != null)
699                ? enter.getEnv(ts)
700                : null;
701    }
702
703    private void ensureEntered(String methodName) {
704        if (javacTaskImpl != null) {
705            javacTaskImpl.ensureEntered();
706        }
707        if (!javaCompiler.isEnterDone()) {
708            throw new IllegalStateException("Cannot use Elements." + methodName + " before the TaskEvent.Kind.ENTER finished event.");
709        }
710    }
711
712    /**
713     * Returns an object cast to the specified type.
714     * @throws NullPointerException if the object is {@code null}
715     * @throws IllegalArgumentException if the object is of the wrong type
716     */
717    private static <T> T cast(Class<T> clazz, Object o) {
718        if (! clazz.isInstance(o))
719            throw new IllegalArgumentException(o.toString());
720        return clazz.cast(o);
721    }
722}
723