Checker.java revision 2837:1e3266d870d6 
1/*
2 * Copyright (c) 2012, 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 */
25
26package com.sun.tools.doclint;
27
28import java.io.IOException;
29import java.io.StringWriter;
30import java.net.URI;
31import java.net.URISyntaxException;
32import java.util.Deque;
33import java.util.EnumSet;
34import java.util.HashMap;
35import java.util.HashSet;
36import java.util.LinkedList;
37import java.util.List;
38import java.util.Map;
39import java.util.Set;
40import java.util.regex.Matcher;
41import java.util.regex.Pattern;
42
43import javax.lang.model.element.Element;
44import javax.lang.model.element.ElementKind;
45import javax.lang.model.element.ExecutableElement;
46import javax.lang.model.element.Name;
47import javax.lang.model.element.VariableElement;
48import javax.lang.model.type.TypeKind;
49import javax.lang.model.type.TypeMirror;
50import javax.tools.Diagnostic.Kind;
51import javax.tools.JavaFileObject;
52
53import com.sun.source.doctree.AttributeTree;
54import com.sun.source.doctree.AuthorTree;
55import com.sun.source.doctree.DocCommentTree;
56import com.sun.source.doctree.DocRootTree;
57import com.sun.source.doctree.DocTree;
58import com.sun.source.doctree.EndElementTree;
59import com.sun.source.doctree.EntityTree;
60import com.sun.source.doctree.ErroneousTree;
61import com.sun.source.doctree.IdentifierTree;
62import com.sun.source.doctree.InheritDocTree;
63import com.sun.source.doctree.LinkTree;
64import com.sun.source.doctree.LiteralTree;
65import com.sun.source.doctree.ParamTree;
66import com.sun.source.doctree.ReferenceTree;
67import com.sun.source.doctree.ReturnTree;
68import com.sun.source.doctree.SerialDataTree;
69import com.sun.source.doctree.SerialFieldTree;
70import com.sun.source.doctree.SinceTree;
71import com.sun.source.doctree.StartElementTree;
72import com.sun.source.doctree.TextTree;
73import com.sun.source.doctree.ThrowsTree;
74import com.sun.source.doctree.UnknownBlockTagTree;
75import com.sun.source.doctree.UnknownInlineTagTree;
76import com.sun.source.doctree.ValueTree;
77import com.sun.source.doctree.VersionTree;
78import com.sun.source.tree.Tree;
79import com.sun.source.util.DocTreePath;
80import com.sun.source.util.DocTreePathScanner;
81import com.sun.source.util.TreePath;
82import com.sun.tools.doclint.HtmlTag.AttrKind;
83import com.sun.tools.javac.tree.DocPretty;
84import com.sun.tools.javac.util.Assert;
85import com.sun.tools.javac.util.DefinedBy;
86import com.sun.tools.javac.util.DefinedBy.Api;
87import com.sun.tools.javac.util.StringUtils;
88import static com.sun.tools.doclint.Messages.Group.*;
89
90
91/**
92 * Validate a doc comment.
93 *
94 * <p><b>This is NOT part of any supported API.
95 * If you write code that depends on this, you do so at your own
96 * risk.  This code and its internal interfaces are subject to change
97 * or deletion without notice.</b></p>
98 */
99public class Checker extends DocTreePathScanner<Void, Void> {
100    final Env env;
101
102    Set<Element> foundParams = new HashSet<>();
103    Set<TypeMirror> foundThrows = new HashSet<>();
104    Map<Element, Set<String>> foundAnchors = new HashMap<>();
105    boolean foundInheritDoc = false;
106    boolean foundReturn = false;
107
108    public enum Flag {
109        TABLE_HAS_CAPTION,
110        HAS_ELEMENT,
111        HAS_INLINE_TAG,
112        HAS_TEXT,
113        REPORTED_BAD_INLINE
114    }
115
116    static class TagStackItem {
117        final DocTree tree; // typically, but not always, StartElementTree
118        final HtmlTag tag;
119        final Set<HtmlTag.Attr> attrs;
120        final Set<Flag> flags;
121        TagStackItem(DocTree tree, HtmlTag tag) {
122            this.tree = tree;
123            this.tag = tag;
124            attrs = EnumSet.noneOf(HtmlTag.Attr.class);
125            flags = EnumSet.noneOf(Flag.class);
126        }
127        @Override
128        public String toString() {
129            return String.valueOf(tag);
130        }
131    }
132
133    private Deque<TagStackItem> tagStack; // TODO: maybe want to record starting tree as well
134    private HtmlTag currHeaderTag;
135
136    private final int implicitHeaderLevel;
137
138    // <editor-fold defaultstate="collapsed" desc="Top level">
139
140    Checker(Env env) {
141        this.env = Assert.checkNonNull(env);
142        tagStack = new LinkedList<>();
143        implicitHeaderLevel = env.implicitHeaderLevel;
144    }
145
146    public Void scan(DocCommentTree tree, TreePath p) {
147        env.setCurrent(p, tree);
148
149        boolean isOverridingMethod = !env.currOverriddenMethods.isEmpty();
150
151        if (p.getLeaf().getKind() == Tree.Kind.PACKAGE) {
152            // If p points to a package, the implied declaration is the
153            // package declaration (if any) for the compilation unit.
154            // Handle this case specially, because doc comments are only
155            // expected in package-info files.
156            JavaFileObject fo = p.getCompilationUnit().getSourceFile();
157            boolean isPkgInfo = fo.isNameCompatible("package-info", JavaFileObject.Kind.SOURCE);
158            if (tree == null) {
159                if (isPkgInfo)
160                    reportMissing("dc.missing.comment");
161                return null;
162            } else {
163                if (!isPkgInfo)
164                    reportReference("dc.unexpected.comment");
165            }
166        } else {
167            if (tree == null) {
168                if (!isSynthetic() && !isOverridingMethod)
169                    reportMissing("dc.missing.comment");
170                return null;
171            }
172        }
173
174        tagStack.clear();
175        currHeaderTag = null;
176
177        foundParams.clear();
178        foundThrows.clear();
179        foundInheritDoc = false;
180        foundReturn = false;
181
182        scan(new DocTreePath(p, tree), null);
183
184        if (!isOverridingMethod) {
185            switch (env.currElement.getKind()) {
186                case METHOD:
187                case CONSTRUCTOR: {
188                    ExecutableElement ee = (ExecutableElement) env.currElement;
189                    checkParamsDocumented(ee.getTypeParameters());
190                    checkParamsDocumented(ee.getParameters());
191                    switch (ee.getReturnType().getKind()) {
192                        case VOID:
193                        case NONE:
194                            break;
195                        default:
196                            if (!foundReturn
197                                    && !foundInheritDoc
198                                    && !env.types.isSameType(ee.getReturnType(), env.java_lang_Void)) {
199                                reportMissing("dc.missing.return");
200                            }
201                    }
202                    checkThrowsDocumented(ee.getThrownTypes());
203                }
204            }
205        }
206
207        return null;
208    }
209
210    private void reportMissing(String code, Object... args) {
211        env.messages.report(MISSING, Kind.WARNING, env.currPath.getLeaf(), code, args);
212    }
213
214    private void reportReference(String code, Object... args) {
215        env.messages.report(REFERENCE, Kind.WARNING, env.currPath.getLeaf(), code, args);
216    }
217
218    @Override @DefinedBy(Api.COMPILER_TREE)
219    public Void visitDocComment(DocCommentTree tree, Void ignore) {
220        super.visitDocComment(tree, ignore);
221        for (TagStackItem tsi: tagStack) {
222            warnIfEmpty(tsi, null);
223            if (tsi.tree.getKind() == DocTree.Kind.START_ELEMENT
224                    && tsi.tag.endKind == HtmlTag.EndKind.REQUIRED) {
225                StartElementTree t = (StartElementTree) tsi.tree;
226                env.messages.error(HTML, t, "dc.tag.not.closed", t.getName());
227            }
228        }
229        return null;
230    }
231    // </editor-fold>
232
233    // <editor-fold defaultstate="collapsed" desc="Text and entities.">
234
235    @Override @DefinedBy(Api.COMPILER_TREE)
236    public Void visitText(TextTree tree, Void ignore) {
237        if (hasNonWhitespace(tree)) {
238            checkAllowsText(tree);
239            markEnclosingTag(Flag.HAS_TEXT);
240        }
241        return null;
242    }
243
244    @Override @DefinedBy(Api.COMPILER_TREE)
245    public Void visitEntity(EntityTree tree, Void ignore) {
246        checkAllowsText(tree);
247        markEnclosingTag(Flag.HAS_TEXT);
248        String name = tree.getName().toString();
249        if (name.startsWith("#")) {
250            int v = StringUtils.toLowerCase(name).startsWith("#x")
251                    ? Integer.parseInt(name.substring(2), 16)
252                    : Integer.parseInt(name.substring(1), 10);
253            if (!Entity.isValid(v)) {
254                env.messages.error(HTML, tree, "dc.entity.invalid", name);
255            }
256        } else if (!Entity.isValid(name)) {
257            env.messages.error(HTML, tree, "dc.entity.invalid", name);
258        }
259        return null;
260    }
261
262    void checkAllowsText(DocTree tree) {
263        TagStackItem top = tagStack.peek();
264        if (top != null
265                && top.tree.getKind() == DocTree.Kind.START_ELEMENT
266                && !top.tag.acceptsText()) {
267            if (top.flags.add(Flag.REPORTED_BAD_INLINE)) {
268                env.messages.error(HTML, tree, "dc.text.not.allowed",
269                        ((StartElementTree) top.tree).getName());
270            }
271        }
272    }
273
274    // </editor-fold>
275
276    // <editor-fold defaultstate="collapsed" desc="HTML elements">
277
278    @Override @DefinedBy(Api.COMPILER_TREE)
279    public Void visitStartElement(StartElementTree tree, Void ignore) {
280        final Name treeName = tree.getName();
281        final HtmlTag t = HtmlTag.get(treeName);
282        if (t == null) {
283            env.messages.error(HTML, tree, "dc.tag.unknown", treeName);
284        } else {
285            boolean done = false;
286            for (TagStackItem tsi: tagStack) {
287                if (tsi.tag.accepts(t)) {
288                    while (tagStack.peek() != tsi) {
289                        warnIfEmpty(tagStack.peek(), null);
290                        tagStack.pop();
291                    }
292                    done = true;
293                    break;
294                } else if (tsi.tag.endKind != HtmlTag.EndKind.OPTIONAL) {
295                    done = true;
296                    break;
297                }
298            }
299            if (!done && HtmlTag.BODY.accepts(t)) {
300                while (!tagStack.isEmpty()) {
301                    warnIfEmpty(tagStack.peek(), null);
302                    tagStack.pop();
303                }
304            }
305
306            markEnclosingTag(Flag.HAS_ELEMENT);
307            checkStructure(tree, t);
308
309            // tag specific checks
310            switch (t) {
311                // check for out of sequence headers, such as <h1>...</h1>  <h3>...</h3>
312                case H1: case H2: case H3: case H4: case H5: case H6:
313                    checkHeader(tree, t);
314                    break;
315            }
316
317            if (t.flags.contains(HtmlTag.Flag.NO_NEST)) {
318                for (TagStackItem i: tagStack) {
319                    if (t == i.tag) {
320                        env.messages.warning(HTML, tree, "dc.tag.nested.not.allowed", treeName);
321                        break;
322                    }
323                }
324            }
325        }
326
327        // check for self closing tags, such as <a id="name"/>
328        if (tree.isSelfClosing()) {
329            env.messages.error(HTML, tree, "dc.tag.self.closing", treeName);
330        }
331
332        try {
333            TagStackItem parent = tagStack.peek();
334            TagStackItem top = new TagStackItem(tree, t);
335            tagStack.push(top);
336
337            super.visitStartElement(tree, ignore);
338
339            // handle attributes that may or may not have been found in start element
340            if (t != null) {
341                switch (t) {
342                    case CAPTION:
343                        if (parent != null && parent.tag == HtmlTag.TABLE)
344                            parent.flags.add(Flag.TABLE_HAS_CAPTION);
345                        break;
346
347                    case IMG:
348                        if (!top.attrs.contains(HtmlTag.Attr.ALT))
349                            env.messages.error(ACCESSIBILITY, tree, "dc.no.alt.attr.for.image");
350                        break;
351                }
352            }
353
354            return null;
355        } finally {
356
357            if (t == null || t.endKind == HtmlTag.EndKind.NONE)
358                tagStack.pop();
359        }
360    }
361
362    private void checkStructure(StartElementTree tree, HtmlTag t) {
363        Name treeName = tree.getName();
364        TagStackItem top = tagStack.peek();
365        switch (t.blockType) {
366            case BLOCK:
367                if (top == null || top.tag.accepts(t))
368                    return;
369
370                switch (top.tree.getKind()) {
371                    case START_ELEMENT: {
372                        if (top.tag.blockType == HtmlTag.BlockType.INLINE) {
373                            Name name = ((StartElementTree) top.tree).getName();
374                            env.messages.error(HTML, tree, "dc.tag.not.allowed.inline.element",
375                                    treeName, name);
376                            return;
377                        }
378                    }
379                    break;
380
381                    case LINK:
382                    case LINK_PLAIN: {
383                        String name = top.tree.getKind().tagName;
384                        env.messages.error(HTML, tree, "dc.tag.not.allowed.inline.tag",
385                                treeName, name);
386                        return;
387                    }
388                }
389                break;
390
391            case INLINE:
392                if (top == null || top.tag.accepts(t))
393                    return;
394                break;
395
396            case LIST_ITEM:
397            case TABLE_ITEM:
398                if (top != null) {
399                    // reset this flag so subsequent bad inline content gets reported
400                    top.flags.remove(Flag.REPORTED_BAD_INLINE);
401                    if (top.tag.accepts(t))
402                        return;
403                }
404                break;
405
406            case OTHER:
407                env.messages.error(HTML, tree, "dc.tag.not.allowed", treeName);
408                return;
409        }
410
411        env.messages.error(HTML, tree, "dc.tag.not.allowed.here", treeName);
412    }
413
414    private void checkHeader(StartElementTree tree, HtmlTag tag) {
415        // verify the new tag
416        if (getHeaderLevel(tag) > getHeaderLevel(currHeaderTag) + 1) {
417            if (currHeaderTag == null) {
418                env.messages.error(ACCESSIBILITY, tree, "dc.tag.header.sequence.1", tag);
419            } else {
420                env.messages.error(ACCESSIBILITY, tree, "dc.tag.header.sequence.2",
421                    tag, currHeaderTag);
422            }
423        }
424
425        currHeaderTag = tag;
426    }
427
428    private int getHeaderLevel(HtmlTag tag) {
429        if (tag == null)
430            return implicitHeaderLevel;
431        switch (tag) {
432            case H1: return 1;
433            case H2: return 2;
434            case H3: return 3;
435            case H4: return 4;
436            case H5: return 5;
437            case H6: return 6;
438            default: throw new IllegalArgumentException();
439        }
440    }
441
442    @Override @DefinedBy(Api.COMPILER_TREE)
443    public Void visitEndElement(EndElementTree tree, Void ignore) {
444        final Name treeName = tree.getName();
445        final HtmlTag t = HtmlTag.get(treeName);
446        if (t == null) {
447            env.messages.error(HTML, tree, "dc.tag.unknown", treeName);
448        } else if (t.endKind == HtmlTag.EndKind.NONE) {
449            env.messages.error(HTML, tree, "dc.tag.end.not.permitted", treeName);
450        } else {
451            boolean done = false;
452            while (!tagStack.isEmpty()) {
453                TagStackItem top = tagStack.peek();
454                if (t == top.tag) {
455                    switch (t) {
456                        case TABLE:
457                            if (!top.attrs.contains(HtmlTag.Attr.SUMMARY)
458                                    && !top.flags.contains(Flag.TABLE_HAS_CAPTION)) {
459                                env.messages.error(ACCESSIBILITY, tree,
460                                        "dc.no.summary.or.caption.for.table");
461                            }
462                    }
463                    warnIfEmpty(top, tree);
464                    tagStack.pop();
465                    done = true;
466                    break;
467                } else if (top.tag == null || top.tag.endKind != HtmlTag.EndKind.REQUIRED) {
468                    tagStack.pop();
469                } else {
470                    boolean found = false;
471                    for (TagStackItem si: tagStack) {
472                        if (si.tag == t) {
473                            found = true;
474                            break;
475                        }
476                    }
477                    if (found && top.tree.getKind() == DocTree.Kind.START_ELEMENT) {
478                        env.messages.error(HTML, top.tree, "dc.tag.start.unmatched",
479                                ((StartElementTree) top.tree).getName());
480                        tagStack.pop();
481                    } else {
482                        env.messages.error(HTML, tree, "dc.tag.end.unexpected", treeName);
483                        done = true;
484                        break;
485                    }
486                }
487            }
488
489            if (!done && tagStack.isEmpty()) {
490                env.messages.error(HTML, tree, "dc.tag.end.unexpected", treeName);
491            }
492        }
493
494        return super.visitEndElement(tree, ignore);
495    }
496
497    void warnIfEmpty(TagStackItem tsi, DocTree endTree) {
498        if (tsi.tag != null && tsi.tree instanceof StartElementTree) {
499            if (tsi.tag.flags.contains(HtmlTag.Flag.EXPECT_CONTENT)
500                    && !tsi.flags.contains(Flag.HAS_TEXT)
501                    && !tsi.flags.contains(Flag.HAS_ELEMENT)
502                    && !tsi.flags.contains(Flag.HAS_INLINE_TAG)) {
503                DocTree tree = (endTree != null) ? endTree : tsi.tree;
504                Name treeName = ((StartElementTree) tsi.tree).getName();
505                env.messages.warning(HTML, tree, "dc.tag.empty", treeName);
506            }
507        }
508    }
509
510    // </editor-fold>
511
512    // <editor-fold defaultstate="collapsed" desc="HTML attributes">
513
514    @Override @DefinedBy(Api.COMPILER_TREE) @SuppressWarnings("fallthrough")
515    public Void visitAttribute(AttributeTree tree, Void ignore) {
516        HtmlTag currTag = tagStack.peek().tag;
517        if (currTag != null) {
518            Name name = tree.getName();
519            HtmlTag.Attr attr = currTag.getAttr(name);
520            if (attr != null) {
521                boolean first = tagStack.peek().attrs.add(attr);
522                if (!first)
523                    env.messages.error(HTML, tree, "dc.attr.repeated", name);
524            }
525            AttrKind k = currTag.getAttrKind(name);
526            switch (k) {
527                case OK:
528                    break;
529
530                case INVALID:
531                    env.messages.error(HTML, tree, "dc.attr.unknown", name);
532                    break;
533
534                case OBSOLETE:
535                    env.messages.warning(ACCESSIBILITY, tree, "dc.attr.obsolete", name);
536                    break;
537
538                case USE_CSS:
539                    env.messages.warning(ACCESSIBILITY, tree, "dc.attr.obsolete.use.css", name);
540                    break;
541            }
542
543            if (attr != null) {
544                switch (attr) {
545                    case NAME:
546                        if (currTag != HtmlTag.A) {
547                            break;
548                        }
549                        // fallthrough
550                    case ID:
551                        String value = getAttrValue(tree);
552                        if (value == null) {
553                            env.messages.error(HTML, tree, "dc.anchor.value.missing");
554                        } else {
555                            if (!validName.matcher(value).matches()) {
556                                env.messages.error(HTML, tree, "dc.invalid.anchor", value);
557                            }
558                            if (!checkAnchor(value)) {
559                                env.messages.error(HTML, tree, "dc.anchor.already.defined", value);
560                            }
561                        }
562                        break;
563
564                    case HREF:
565                        if (currTag == HtmlTag.A) {
566                            String v = getAttrValue(tree);
567                            if (v == null || v.isEmpty()) {
568                                env.messages.error(HTML, tree, "dc.attr.lacks.value");
569                            } else {
570                                Matcher m = docRoot.matcher(v);
571                                if (m.matches()) {
572                                    String rest = m.group(2);
573                                    if (!rest.isEmpty())
574                                        checkURI(tree, rest);
575                                } else {
576                                    checkURI(tree, v);
577                                }
578                            }
579                        }
580                        break;
581
582                    case VALUE:
583                        if (currTag == HtmlTag.LI) {
584                            String v = getAttrValue(tree);
585                            if (v == null || v.isEmpty()) {
586                                env.messages.error(HTML, tree, "dc.attr.lacks.value");
587                            } else if (!validNumber.matcher(v).matches()) {
588                                env.messages.error(HTML, tree, "dc.attr.not.number");
589                            }
590                        }
591                        break;
592                }
593            }
594        }
595
596        // TODO: basic check on value
597
598        return super.visitAttribute(tree, ignore);
599    }
600
601    private boolean checkAnchor(String name) {
602        Element e = getEnclosingPackageOrClass(env.currElement);
603        if (e == null)
604            return true;
605        Set<String> set = foundAnchors.get(e);
606        if (set == null)
607            foundAnchors.put(e, set = new HashSet<>());
608        return set.add(name);
609    }
610
611    private Element getEnclosingPackageOrClass(Element e) {
612        while (e != null) {
613            switch (e.getKind()) {
614                case CLASS:
615                case ENUM:
616                case INTERFACE:
617                case PACKAGE:
618                    return e;
619                default:
620                    e = e.getEnclosingElement();
621            }
622        }
623        return e;
624    }
625
626    // http://www.w3.org/TR/html401/types.html#type-name
627    private static final Pattern validName = Pattern.compile("[A-Za-z][A-Za-z0-9-_:.]*");
628
629    private static final Pattern validNumber = Pattern.compile("-?[0-9]+");
630
631    // pattern to remove leading {@docRoot}/?
632    private static final Pattern docRoot = Pattern.compile("(?i)(\\{@docRoot *\\}/?)?(.*)");
633
634    private String getAttrValue(AttributeTree tree) {
635        if (tree.getValue() == null)
636            return null;
637
638        StringWriter sw = new StringWriter();
639        try {
640            new DocPretty(sw).print(tree.getValue());
641        } catch (IOException e) {
642            // cannot happen
643        }
644        // ignore potential use of entities for now
645        return sw.toString();
646    }
647
648    private void checkURI(AttributeTree tree, String uri) {
649        try {
650            URI u = new URI(uri);
651        } catch (URISyntaxException e) {
652            env.messages.error(HTML, tree, "dc.invalid.uri", uri);
653        }
654    }
655    // </editor-fold>
656
657    // <editor-fold defaultstate="collapsed" desc="javadoc tags">
658
659    @Override @DefinedBy(Api.COMPILER_TREE)
660    public Void visitAuthor(AuthorTree tree, Void ignore) {
661        warnIfEmpty(tree, tree.getName());
662        return super.visitAuthor(tree, ignore);
663    }
664
665    @Override @DefinedBy(Api.COMPILER_TREE)
666    public Void visitDocRoot(DocRootTree tree, Void ignore) {
667        markEnclosingTag(Flag.HAS_INLINE_TAG);
668        return super.visitDocRoot(tree, ignore);
669    }
670
671    @Override @DefinedBy(Api.COMPILER_TREE)
672    public Void visitInheritDoc(InheritDocTree tree, Void ignore) {
673        markEnclosingTag(Flag.HAS_INLINE_TAG);
674        // TODO: verify on overridden method
675        foundInheritDoc = true;
676        return super.visitInheritDoc(tree, ignore);
677    }
678
679    @Override @DefinedBy(Api.COMPILER_TREE)
680    public Void visitLink(LinkTree tree, Void ignore) {
681        markEnclosingTag(Flag.HAS_INLINE_TAG);
682        // simulate inline context on tag stack
683        HtmlTag t = (tree.getKind() == DocTree.Kind.LINK)
684                ? HtmlTag.CODE : HtmlTag.SPAN;
685        tagStack.push(new TagStackItem(tree, t));
686        try {
687            return super.visitLink(tree, ignore);
688        } finally {
689            tagStack.pop();
690        }
691    }
692
693    @Override @DefinedBy(Api.COMPILER_TREE)
694    public Void visitLiteral(LiteralTree tree, Void ignore) {
695        markEnclosingTag(Flag.HAS_INLINE_TAG);
696        if (tree.getKind() == DocTree.Kind.CODE) {
697            for (TagStackItem tsi: tagStack) {
698                if (tsi.tag == HtmlTag.CODE) {
699                    env.messages.warning(HTML, tree, "dc.tag.code.within.code");
700                    break;
701                }
702            }
703        }
704        return super.visitLiteral(tree, ignore);
705    }
706
707    @Override @DefinedBy(Api.COMPILER_TREE)
708    @SuppressWarnings("fallthrough")
709    public Void visitParam(ParamTree tree, Void ignore) {
710        boolean typaram = tree.isTypeParameter();
711        IdentifierTree nameTree = tree.getName();
712        Element paramElement = nameTree != null ? env.trees.getElement(new DocTreePath(getCurrentPath(), nameTree)) : null;
713
714        if (paramElement == null) {
715            switch (env.currElement.getKind()) {
716                case CLASS: case INTERFACE: {
717                    if (!typaram) {
718                        env.messages.error(REFERENCE, tree, "dc.invalid.param");
719                        break;
720                    }
721                }
722                case METHOD: case CONSTRUCTOR: {
723                    env.messages.error(REFERENCE, nameTree, "dc.param.name.not.found");
724                    break;
725                }
726
727                default:
728                    env.messages.error(REFERENCE, tree, "dc.invalid.param");
729                    break;
730            }
731        } else {
732            foundParams.add(paramElement);
733        }
734
735        warnIfEmpty(tree, tree.getDescription());
736        return super.visitParam(tree, ignore);
737    }
738
739    private void checkParamsDocumented(List<? extends Element> list) {
740        if (foundInheritDoc)
741            return;
742
743        for (Element e: list) {
744            if (!foundParams.contains(e)) {
745                CharSequence paramName = (e.getKind() == ElementKind.TYPE_PARAMETER)
746                        ? "<" + e.getSimpleName() + ">"
747                        : e.getSimpleName();
748                reportMissing("dc.missing.param", paramName);
749            }
750        }
751    }
752
753    @Override @DefinedBy(Api.COMPILER_TREE)
754    public Void visitReference(ReferenceTree tree, Void ignore) {
755        String sig = tree.getSignature();
756        if (sig.contains("<") || sig.contains(">"))
757            env.messages.error(REFERENCE, tree, "dc.type.arg.not.allowed");
758
759        Element e = env.trees.getElement(getCurrentPath());
760        if (e == null)
761            env.messages.error(REFERENCE, tree, "dc.ref.not.found");
762        return super.visitReference(tree, ignore);
763    }
764
765    @Override @DefinedBy(Api.COMPILER_TREE)
766    public Void visitReturn(ReturnTree tree, Void ignore) {
767        Element e = env.trees.getElement(env.currPath);
768        if (e.getKind() != ElementKind.METHOD
769                || ((ExecutableElement) e).getReturnType().getKind() == TypeKind.VOID)
770            env.messages.error(REFERENCE, tree, "dc.invalid.return");
771        foundReturn = true;
772        warnIfEmpty(tree, tree.getDescription());
773        return super.visitReturn(tree, ignore);
774    }
775
776    @Override @DefinedBy(Api.COMPILER_TREE)
777    public Void visitSerialData(SerialDataTree tree, Void ignore) {
778        warnIfEmpty(tree, tree.getDescription());
779        return super.visitSerialData(tree, ignore);
780    }
781
782    @Override @DefinedBy(Api.COMPILER_TREE)
783    public Void visitSerialField(SerialFieldTree tree, Void ignore) {
784        warnIfEmpty(tree, tree.getDescription());
785        return super.visitSerialField(tree, ignore);
786    }
787
788    @Override @DefinedBy(Api.COMPILER_TREE)
789    public Void visitSince(SinceTree tree, Void ignore) {
790        warnIfEmpty(tree, tree.getBody());
791        return super.visitSince(tree, ignore);
792    }
793
794    @Override @DefinedBy(Api.COMPILER_TREE)
795    public Void visitThrows(ThrowsTree tree, Void ignore) {
796        ReferenceTree exName = tree.getExceptionName();
797        Element ex = env.trees.getElement(new DocTreePath(getCurrentPath(), exName));
798        if (ex == null) {
799            env.messages.error(REFERENCE, tree, "dc.ref.not.found");
800        } else if (isThrowable(ex.asType())) {
801            switch (env.currElement.getKind()) {
802                case CONSTRUCTOR:
803                case METHOD:
804                    if (isCheckedException(ex.asType())) {
805                        ExecutableElement ee = (ExecutableElement) env.currElement;
806                        checkThrowsDeclared(exName, ex.asType(), ee.getThrownTypes());
807                    }
808                    break;
809                default:
810                    env.messages.error(REFERENCE, tree, "dc.invalid.throws");
811            }
812        } else {
813            env.messages.error(REFERENCE, tree, "dc.invalid.throws");
814        }
815        warnIfEmpty(tree, tree.getDescription());
816        return scan(tree.getDescription(), ignore);
817    }
818
819    private boolean isThrowable(TypeMirror tm) {
820        switch (tm.getKind()) {
821            case DECLARED:
822            case TYPEVAR:
823                return env.types.isAssignable(tm, env.java_lang_Throwable);
824        }
825        return false;
826    }
827
828    private void checkThrowsDeclared(ReferenceTree tree, TypeMirror t, List<? extends TypeMirror> list) {
829        boolean found = false;
830        for (TypeMirror tl : list) {
831            if (env.types.isAssignable(t, tl)) {
832                foundThrows.add(tl);
833                found = true;
834            }
835        }
836        if (!found)
837            env.messages.error(REFERENCE, tree, "dc.exception.not.thrown", t);
838    }
839
840    private void checkThrowsDocumented(List<? extends TypeMirror> list) {
841        if (foundInheritDoc)
842            return;
843
844        for (TypeMirror tl: list) {
845            if (isCheckedException(tl) && !foundThrows.contains(tl))
846                reportMissing("dc.missing.throws", tl);
847        }
848    }
849
850    @Override @DefinedBy(Api.COMPILER_TREE)
851    public Void visitUnknownBlockTag(UnknownBlockTagTree tree, Void ignore) {
852        checkUnknownTag(tree, tree.getTagName());
853        return super.visitUnknownBlockTag(tree, ignore);
854    }
855
856    @Override @DefinedBy(Api.COMPILER_TREE)
857    public Void visitUnknownInlineTag(UnknownInlineTagTree tree, Void ignore) {
858        checkUnknownTag(tree, tree.getTagName());
859        return super.visitUnknownInlineTag(tree, ignore);
860    }
861
862    private void checkUnknownTag(DocTree tree, String tagName) {
863        if (env.customTags != null && !env.customTags.contains(tagName))
864            env.messages.error(SYNTAX, tree, "dc.tag.unknown", tagName);
865    }
866
867    @Override @DefinedBy(Api.COMPILER_TREE)
868    public Void visitValue(ValueTree tree, Void ignore) {
869        ReferenceTree ref = tree.getReference();
870        if (ref == null || ref.getSignature().isEmpty()) {
871            if (!isConstant(env.currElement))
872                env.messages.error(REFERENCE, tree, "dc.value.not.allowed.here");
873        } else {
874            Element e = env.trees.getElement(new DocTreePath(getCurrentPath(), ref));
875            if (!isConstant(e))
876                env.messages.error(REFERENCE, tree, "dc.value.not.a.constant");
877        }
878
879        markEnclosingTag(Flag.HAS_INLINE_TAG);
880        return super.visitValue(tree, ignore);
881    }
882
883    private boolean isConstant(Element e) {
884        if (e == null)
885            return false;
886
887        switch (e.getKind()) {
888            case FIELD:
889                Object value = ((VariableElement) e).getConstantValue();
890                return (value != null); // can't distinguish "not a constant" from "constant is null"
891            default:
892                return false;
893        }
894    }
895
896    @Override @DefinedBy(Api.COMPILER_TREE)
897    public Void visitVersion(VersionTree tree, Void ignore) {
898        warnIfEmpty(tree, tree.getBody());
899        return super.visitVersion(tree, ignore);
900    }
901
902    @Override @DefinedBy(Api.COMPILER_TREE)
903    public Void visitErroneous(ErroneousTree tree, Void ignore) {
904        env.messages.error(SYNTAX, tree, null, tree.getDiagnostic().getMessage(null));
905        return null;
906    }
907    // </editor-fold>
908
909    // <editor-fold defaultstate="collapsed" desc="Utility methods">
910
911    private boolean isCheckedException(TypeMirror t) {
912        return !(env.types.isAssignable(t, env.java_lang_Error)
913                || env.types.isAssignable(t, env.java_lang_RuntimeException));
914    }
915
916    private boolean isSynthetic() {
917        switch (env.currElement.getKind()) {
918            case CONSTRUCTOR:
919                // A synthetic default constructor has the same pos as the
920                // enclosing class
921                TreePath p = env.currPath;
922                return env.getPos(p) == env.getPos(p.getParentPath());
923        }
924        return false;
925    }
926
927    void markEnclosingTag(Flag flag) {
928        TagStackItem top = tagStack.peek();
929        if (top != null)
930            top.flags.add(flag);
931    }
932
933    String toString(TreePath p) {
934        StringBuilder sb = new StringBuilder("TreePath[");
935        toString(p, sb);
936        sb.append("]");
937        return sb.toString();
938    }
939
940    void toString(TreePath p, StringBuilder sb) {
941        TreePath parent = p.getParentPath();
942        if (parent != null) {
943            toString(parent, sb);
944            sb.append(",");
945        }
946       sb.append(p.getLeaf().getKind()).append(":").append(env.getPos(p)).append(":S").append(env.getStartPos(p));
947    }
948
949    void warnIfEmpty(DocTree tree, List<? extends DocTree> list) {
950        for (DocTree d: list) {
951            switch (d.getKind()) {
952                case TEXT:
953                    if (hasNonWhitespace((TextTree) d))
954                        return;
955                    break;
956                default:
957                    return;
958            }
959        }
960        env.messages.warning(SYNTAX, tree, "dc.empty", tree.getKind().tagName);
961    }
962
963    boolean hasNonWhitespace(TextTree tree) {
964        String s = tree.getBody();
965        for (int i = 0; i < s.length(); i++) {
966            if (!Character.isWhitespace(s.charAt(i)))
967                return true;
968        }
969        return false;
970    }
971
972    // </editor-fold>
973
974}
975