Checker.java revision 2846:072008f47620 
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.initTypes();
148        env.setCurrent(p, tree);
149
150        boolean isOverridingMethod = !env.currOverriddenMethods.isEmpty();
151
152        if (p.getLeaf().getKind() == Tree.Kind.PACKAGE) {
153            // If p points to a package, the implied declaration is the
154            // package declaration (if any) for the compilation unit.
155            // Handle this case specially, because doc comments are only
156            // expected in package-info files.
157            JavaFileObject fo = p.getCompilationUnit().getSourceFile();
158            boolean isPkgInfo = fo.isNameCompatible("package-info", JavaFileObject.Kind.SOURCE);
159            if (tree == null) {
160                if (isPkgInfo)
161                    reportMissing("dc.missing.comment");
162                return null;
163            } else {
164                if (!isPkgInfo)
165                    reportReference("dc.unexpected.comment");
166            }
167        } else {
168            if (tree == null) {
169                if (!isSynthetic() && !isOverridingMethod)
170                    reportMissing("dc.missing.comment");
171                return null;
172            }
173        }
174
175        tagStack.clear();
176        currHeaderTag = null;
177
178        foundParams.clear();
179        foundThrows.clear();
180        foundInheritDoc = false;
181        foundReturn = false;
182
183        scan(new DocTreePath(p, tree), null);
184
185        if (!isOverridingMethod) {
186            switch (env.currElement.getKind()) {
187                case METHOD:
188                case CONSTRUCTOR: {
189                    ExecutableElement ee = (ExecutableElement) env.currElement;
190                    checkParamsDocumented(ee.getTypeParameters());
191                    checkParamsDocumented(ee.getParameters());
192                    switch (ee.getReturnType().getKind()) {
193                        case VOID:
194                        case NONE:
195                            break;
196                        default:
197                            if (!foundReturn
198                                    && !foundInheritDoc
199                                    && !env.types.isSameType(ee.getReturnType(), env.java_lang_Void)) {
200                                reportMissing("dc.missing.return");
201                            }
202                    }
203                    checkThrowsDocumented(ee.getThrownTypes());
204                }
205            }
206        }
207
208        return null;
209    }
210
211    private void reportMissing(String code, Object... args) {
212        env.messages.report(MISSING, Kind.WARNING, env.currPath.getLeaf(), code, args);
213    }
214
215    private void reportReference(String code, Object... args) {
216        env.messages.report(REFERENCE, Kind.WARNING, env.currPath.getLeaf(), code, args);
217    }
218
219    @Override @DefinedBy(Api.COMPILER_TREE)
220    public Void visitDocComment(DocCommentTree tree, Void ignore) {
221        super.visitDocComment(tree, ignore);
222        for (TagStackItem tsi: tagStack) {
223            warnIfEmpty(tsi, null);
224            if (tsi.tree.getKind() == DocTree.Kind.START_ELEMENT
225                    && tsi.tag.endKind == HtmlTag.EndKind.REQUIRED) {
226                StartElementTree t = (StartElementTree) tsi.tree;
227                env.messages.error(HTML, t, "dc.tag.not.closed", t.getName());
228            }
229        }
230        return null;
231    }
232    // </editor-fold>
233
234    // <editor-fold defaultstate="collapsed" desc="Text and entities.">
235
236    @Override @DefinedBy(Api.COMPILER_TREE)
237    public Void visitText(TextTree tree, Void ignore) {
238        if (hasNonWhitespace(tree)) {
239            checkAllowsText(tree);
240            markEnclosingTag(Flag.HAS_TEXT);
241        }
242        return null;
243    }
244
245    @Override @DefinedBy(Api.COMPILER_TREE)
246    public Void visitEntity(EntityTree tree, Void ignore) {
247        checkAllowsText(tree);
248        markEnclosingTag(Flag.HAS_TEXT);
249        String name = tree.getName().toString();
250        if (name.startsWith("#")) {
251            int v = StringUtils.toLowerCase(name).startsWith("#x")
252                    ? Integer.parseInt(name.substring(2), 16)
253                    : Integer.parseInt(name.substring(1), 10);
254            if (!Entity.isValid(v)) {
255                env.messages.error(HTML, tree, "dc.entity.invalid", name);
256            }
257        } else if (!Entity.isValid(name)) {
258            env.messages.error(HTML, tree, "dc.entity.invalid", name);
259        }
260        return null;
261    }
262
263    void checkAllowsText(DocTree tree) {
264        TagStackItem top = tagStack.peek();
265        if (top != null
266                && top.tree.getKind() == DocTree.Kind.START_ELEMENT
267                && !top.tag.acceptsText()) {
268            if (top.flags.add(Flag.REPORTED_BAD_INLINE)) {
269                env.messages.error(HTML, tree, "dc.text.not.allowed",
270                        ((StartElementTree) top.tree).getName());
271            }
272        }
273    }
274
275    // </editor-fold>
276
277    // <editor-fold defaultstate="collapsed" desc="HTML elements">
278
279    @Override @DefinedBy(Api.COMPILER_TREE)
280    public Void visitStartElement(StartElementTree tree, Void ignore) {
281        final Name treeName = tree.getName();
282        final HtmlTag t = HtmlTag.get(treeName);
283        if (t == null) {
284            env.messages.error(HTML, tree, "dc.tag.unknown", treeName);
285        } else {
286            boolean done = false;
287            for (TagStackItem tsi: tagStack) {
288                if (tsi.tag.accepts(t)) {
289                    while (tagStack.peek() != tsi) {
290                        warnIfEmpty(tagStack.peek(), null);
291                        tagStack.pop();
292                    }
293                    done = true;
294                    break;
295                } else if (tsi.tag.endKind != HtmlTag.EndKind.OPTIONAL) {
296                    done = true;
297                    break;
298                }
299            }
300            if (!done && HtmlTag.BODY.accepts(t)) {
301                while (!tagStack.isEmpty()) {
302                    warnIfEmpty(tagStack.peek(), null);
303                    tagStack.pop();
304                }
305            }
306
307            markEnclosingTag(Flag.HAS_ELEMENT);
308            checkStructure(tree, t);
309
310            // tag specific checks
311            switch (t) {
312                // check for out of sequence headers, such as <h1>...</h1>  <h3>...</h3>
313                case H1: case H2: case H3: case H4: case H5: case H6:
314                    checkHeader(tree, t);
315                    break;
316            }
317
318            if (t.flags.contains(HtmlTag.Flag.NO_NEST)) {
319                for (TagStackItem i: tagStack) {
320                    if (t == i.tag) {
321                        env.messages.warning(HTML, tree, "dc.tag.nested.not.allowed", treeName);
322                        break;
323                    }
324                }
325            }
326        }
327
328        // check for self closing tags, such as <a id="name"/>
329        if (tree.isSelfClosing()) {
330            env.messages.error(HTML, tree, "dc.tag.self.closing", treeName);
331        }
332
333        try {
334            TagStackItem parent = tagStack.peek();
335            TagStackItem top = new TagStackItem(tree, t);
336            tagStack.push(top);
337
338            super.visitStartElement(tree, ignore);
339
340            // handle attributes that may or may not have been found in start element
341            if (t != null) {
342                switch (t) {
343                    case CAPTION:
344                        if (parent != null && parent.tag == HtmlTag.TABLE)
345                            parent.flags.add(Flag.TABLE_HAS_CAPTION);
346                        break;
347
348                    case IMG:
349                        if (!top.attrs.contains(HtmlTag.Attr.ALT))
350                            env.messages.error(ACCESSIBILITY, tree, "dc.no.alt.attr.for.image");
351                        break;
352                }
353            }
354
355            return null;
356        } finally {
357
358            if (t == null || t.endKind == HtmlTag.EndKind.NONE)
359                tagStack.pop();
360        }
361    }
362
363    private void checkStructure(StartElementTree tree, HtmlTag t) {
364        Name treeName = tree.getName();
365        TagStackItem top = tagStack.peek();
366        switch (t.blockType) {
367            case BLOCK:
368                if (top == null || top.tag.accepts(t))
369                    return;
370
371                switch (top.tree.getKind()) {
372                    case START_ELEMENT: {
373                        if (top.tag.blockType == HtmlTag.BlockType.INLINE) {
374                            Name name = ((StartElementTree) top.tree).getName();
375                            env.messages.error(HTML, tree, "dc.tag.not.allowed.inline.element",
376                                    treeName, name);
377                            return;
378                        }
379                    }
380                    break;
381
382                    case LINK:
383                    case LINK_PLAIN: {
384                        String name = top.tree.getKind().tagName;
385                        env.messages.error(HTML, tree, "dc.tag.not.allowed.inline.tag",
386                                treeName, name);
387                        return;
388                    }
389                }
390                break;
391
392            case INLINE:
393                if (top == null || top.tag.accepts(t))
394                    return;
395                break;
396
397            case LIST_ITEM:
398            case TABLE_ITEM:
399                if (top != null) {
400                    // reset this flag so subsequent bad inline content gets reported
401                    top.flags.remove(Flag.REPORTED_BAD_INLINE);
402                    if (top.tag.accepts(t))
403                        return;
404                }
405                break;
406
407            case OTHER:
408                env.messages.error(HTML, tree, "dc.tag.not.allowed", treeName);
409                return;
410        }
411
412        env.messages.error(HTML, tree, "dc.tag.not.allowed.here", treeName);
413    }
414
415    private void checkHeader(StartElementTree tree, HtmlTag tag) {
416        // verify the new tag
417        if (getHeaderLevel(tag) > getHeaderLevel(currHeaderTag) + 1) {
418            if (currHeaderTag == null) {
419                env.messages.error(ACCESSIBILITY, tree, "dc.tag.header.sequence.1", tag);
420            } else {
421                env.messages.error(ACCESSIBILITY, tree, "dc.tag.header.sequence.2",
422                    tag, currHeaderTag);
423            }
424        }
425
426        currHeaderTag = tag;
427    }
428
429    private int getHeaderLevel(HtmlTag tag) {
430        if (tag == null)
431            return implicitHeaderLevel;
432        switch (tag) {
433            case H1: return 1;
434            case H2: return 2;
435            case H3: return 3;
436            case H4: return 4;
437            case H5: return 5;
438            case H6: return 6;
439            default: throw new IllegalArgumentException();
440        }
441    }
442
443    @Override @DefinedBy(Api.COMPILER_TREE)
444    public Void visitEndElement(EndElementTree tree, Void ignore) {
445        final Name treeName = tree.getName();
446        final HtmlTag t = HtmlTag.get(treeName);
447        if (t == null) {
448            env.messages.error(HTML, tree, "dc.tag.unknown", treeName);
449        } else if (t.endKind == HtmlTag.EndKind.NONE) {
450            env.messages.error(HTML, tree, "dc.tag.end.not.permitted", treeName);
451        } else {
452            boolean done = false;
453            while (!tagStack.isEmpty()) {
454                TagStackItem top = tagStack.peek();
455                if (t == top.tag) {
456                    switch (t) {
457                        case TABLE:
458                            if (!top.attrs.contains(HtmlTag.Attr.SUMMARY)
459                                    && !top.flags.contains(Flag.TABLE_HAS_CAPTION)) {
460                                env.messages.error(ACCESSIBILITY, tree,
461                                        "dc.no.summary.or.caption.for.table");
462                            }
463                    }
464                    warnIfEmpty(top, tree);
465                    tagStack.pop();
466                    done = true;
467                    break;
468                } else if (top.tag == null || top.tag.endKind != HtmlTag.EndKind.REQUIRED) {
469                    tagStack.pop();
470                } else {
471                    boolean found = false;
472                    for (TagStackItem si: tagStack) {
473                        if (si.tag == t) {
474                            found = true;
475                            break;
476                        }
477                    }
478                    if (found && top.tree.getKind() == DocTree.Kind.START_ELEMENT) {
479                        env.messages.error(HTML, top.tree, "dc.tag.start.unmatched",
480                                ((StartElementTree) top.tree).getName());
481                        tagStack.pop();
482                    } else {
483                        env.messages.error(HTML, tree, "dc.tag.end.unexpected", treeName);
484                        done = true;
485                        break;
486                    }
487                }
488            }
489
490            if (!done && tagStack.isEmpty()) {
491                env.messages.error(HTML, tree, "dc.tag.end.unexpected", treeName);
492            }
493        }
494
495        return super.visitEndElement(tree, ignore);
496    }
497
498    void warnIfEmpty(TagStackItem tsi, DocTree endTree) {
499        if (tsi.tag != null && tsi.tree instanceof StartElementTree) {
500            if (tsi.tag.flags.contains(HtmlTag.Flag.EXPECT_CONTENT)
501                    && !tsi.flags.contains(Flag.HAS_TEXT)
502                    && !tsi.flags.contains(Flag.HAS_ELEMENT)
503                    && !tsi.flags.contains(Flag.HAS_INLINE_TAG)) {
504                DocTree tree = (endTree != null) ? endTree : tsi.tree;
505                Name treeName = ((StartElementTree) tsi.tree).getName();
506                env.messages.warning(HTML, tree, "dc.tag.empty", treeName);
507            }
508        }
509    }
510
511    // </editor-fold>
512
513    // <editor-fold defaultstate="collapsed" desc="HTML attributes">
514
515    @Override @DefinedBy(Api.COMPILER_TREE) @SuppressWarnings("fallthrough")
516    public Void visitAttribute(AttributeTree tree, Void ignore) {
517        HtmlTag currTag = tagStack.peek().tag;
518        if (currTag != null) {
519            Name name = tree.getName();
520            HtmlTag.Attr attr = currTag.getAttr(name);
521            if (attr != null) {
522                boolean first = tagStack.peek().attrs.add(attr);
523                if (!first)
524                    env.messages.error(HTML, tree, "dc.attr.repeated", name);
525            }
526            AttrKind k = currTag.getAttrKind(name);
527            switch (k) {
528                case OK:
529                    break;
530
531                case INVALID:
532                    env.messages.error(HTML, tree, "dc.attr.unknown", name);
533                    break;
534
535                case OBSOLETE:
536                    env.messages.warning(ACCESSIBILITY, tree, "dc.attr.obsolete", name);
537                    break;
538
539                case USE_CSS:
540                    env.messages.warning(ACCESSIBILITY, tree, "dc.attr.obsolete.use.css", name);
541                    break;
542            }
543
544            if (attr != null) {
545                switch (attr) {
546                    case NAME:
547                        if (currTag != HtmlTag.A) {
548                            break;
549                        }
550                        // fallthrough
551                    case ID:
552                        String value = getAttrValue(tree);
553                        if (value == null) {
554                            env.messages.error(HTML, tree, "dc.anchor.value.missing");
555                        } else {
556                            if (!validName.matcher(value).matches()) {
557                                env.messages.error(HTML, tree, "dc.invalid.anchor", value);
558                            }
559                            if (!checkAnchor(value)) {
560                                env.messages.error(HTML, tree, "dc.anchor.already.defined", value);
561                            }
562                        }
563                        break;
564
565                    case HREF:
566                        if (currTag == HtmlTag.A) {
567                            String v = getAttrValue(tree);
568                            if (v == null || v.isEmpty()) {
569                                env.messages.error(HTML, tree, "dc.attr.lacks.value");
570                            } else {
571                                Matcher m = docRoot.matcher(v);
572                                if (m.matches()) {
573                                    String rest = m.group(2);
574                                    if (!rest.isEmpty())
575                                        checkURI(tree, rest);
576                                } else {
577                                    checkURI(tree, v);
578                                }
579                            }
580                        }
581                        break;
582
583                    case VALUE:
584                        if (currTag == HtmlTag.LI) {
585                            String v = getAttrValue(tree);
586                            if (v == null || v.isEmpty()) {
587                                env.messages.error(HTML, tree, "dc.attr.lacks.value");
588                            } else if (!validNumber.matcher(v).matches()) {
589                                env.messages.error(HTML, tree, "dc.attr.not.number");
590                            }
591                        }
592                        break;
593                }
594            }
595        }
596
597        // TODO: basic check on value
598
599        return super.visitAttribute(tree, ignore);
600    }
601
602    private boolean checkAnchor(String name) {
603        Element e = getEnclosingPackageOrClass(env.currElement);
604        if (e == null)
605            return true;
606        Set<String> set = foundAnchors.get(e);
607        if (set == null)
608            foundAnchors.put(e, set = new HashSet<>());
609        return set.add(name);
610    }
611
612    private Element getEnclosingPackageOrClass(Element e) {
613        while (e != null) {
614            switch (e.getKind()) {
615                case CLASS:
616                case ENUM:
617                case INTERFACE:
618                case PACKAGE:
619                    return e;
620                default:
621                    e = e.getEnclosingElement();
622            }
623        }
624        return e;
625    }
626
627    // http://www.w3.org/TR/html401/types.html#type-name
628    private static final Pattern validName = Pattern.compile("[A-Za-z][A-Za-z0-9-_:.]*");
629
630    private static final Pattern validNumber = Pattern.compile("-?[0-9]+");
631
632    // pattern to remove leading {@docRoot}/?
633    private static final Pattern docRoot = Pattern.compile("(?i)(\\{@docRoot *\\}/?)?(.*)");
634
635    private String getAttrValue(AttributeTree tree) {
636        if (tree.getValue() == null)
637            return null;
638
639        StringWriter sw = new StringWriter();
640        try {
641            new DocPretty(sw).print(tree.getValue());
642        } catch (IOException e) {
643            // cannot happen
644        }
645        // ignore potential use of entities for now
646        return sw.toString();
647    }
648
649    private void checkURI(AttributeTree tree, String uri) {
650        try {
651            URI u = new URI(uri);
652        } catch (URISyntaxException e) {
653            env.messages.error(HTML, tree, "dc.invalid.uri", uri);
654        }
655    }
656    // </editor-fold>
657
658    // <editor-fold defaultstate="collapsed" desc="javadoc tags">
659
660    @Override @DefinedBy(Api.COMPILER_TREE)
661    public Void visitAuthor(AuthorTree tree, Void ignore) {
662        warnIfEmpty(tree, tree.getName());
663        return super.visitAuthor(tree, ignore);
664    }
665
666    @Override @DefinedBy(Api.COMPILER_TREE)
667    public Void visitDocRoot(DocRootTree tree, Void ignore) {
668        markEnclosingTag(Flag.HAS_INLINE_TAG);
669        return super.visitDocRoot(tree, ignore);
670    }
671
672    @Override @DefinedBy(Api.COMPILER_TREE)
673    public Void visitInheritDoc(InheritDocTree tree, Void ignore) {
674        markEnclosingTag(Flag.HAS_INLINE_TAG);
675        // TODO: verify on overridden method
676        foundInheritDoc = true;
677        return super.visitInheritDoc(tree, ignore);
678    }
679
680    @Override @DefinedBy(Api.COMPILER_TREE)
681    public Void visitLink(LinkTree tree, Void ignore) {
682        markEnclosingTag(Flag.HAS_INLINE_TAG);
683        // simulate inline context on tag stack
684        HtmlTag t = (tree.getKind() == DocTree.Kind.LINK)
685                ? HtmlTag.CODE : HtmlTag.SPAN;
686        tagStack.push(new TagStackItem(tree, t));
687        try {
688            return super.visitLink(tree, ignore);
689        } finally {
690            tagStack.pop();
691        }
692    }
693
694    @Override @DefinedBy(Api.COMPILER_TREE)
695    public Void visitLiteral(LiteralTree tree, Void ignore) {
696        markEnclosingTag(Flag.HAS_INLINE_TAG);
697        if (tree.getKind() == DocTree.Kind.CODE) {
698            for (TagStackItem tsi: tagStack) {
699                if (tsi.tag == HtmlTag.CODE) {
700                    env.messages.warning(HTML, tree, "dc.tag.code.within.code");
701                    break;
702                }
703            }
704        }
705        return super.visitLiteral(tree, ignore);
706    }
707
708    @Override @DefinedBy(Api.COMPILER_TREE)
709    @SuppressWarnings("fallthrough")
710    public Void visitParam(ParamTree tree, Void ignore) {
711        boolean typaram = tree.isTypeParameter();
712        IdentifierTree nameTree = tree.getName();
713        Element paramElement = nameTree != null ? env.trees.getElement(new DocTreePath(getCurrentPath(), nameTree)) : null;
714
715        if (paramElement == null) {
716            switch (env.currElement.getKind()) {
717                case CLASS: case INTERFACE: {
718                    if (!typaram) {
719                        env.messages.error(REFERENCE, tree, "dc.invalid.param");
720                        break;
721                    }
722                }
723                case METHOD: case CONSTRUCTOR: {
724                    env.messages.error(REFERENCE, nameTree, "dc.param.name.not.found");
725                    break;
726                }
727
728                default:
729                    env.messages.error(REFERENCE, tree, "dc.invalid.param");
730                    break;
731            }
732        } else {
733            foundParams.add(paramElement);
734        }
735
736        warnIfEmpty(tree, tree.getDescription());
737        return super.visitParam(tree, ignore);
738    }
739
740    private void checkParamsDocumented(List<? extends Element> list) {
741        if (foundInheritDoc)
742            return;
743
744        for (Element e: list) {
745            if (!foundParams.contains(e)) {
746                CharSequence paramName = (e.getKind() == ElementKind.TYPE_PARAMETER)
747                        ? "<" + e.getSimpleName() + ">"
748                        : e.getSimpleName();
749                reportMissing("dc.missing.param", paramName);
750            }
751        }
752    }
753
754    @Override @DefinedBy(Api.COMPILER_TREE)
755    public Void visitReference(ReferenceTree tree, Void ignore) {
756        String sig = tree.getSignature();
757        if (sig.contains("<") || sig.contains(">"))
758            env.messages.error(REFERENCE, tree, "dc.type.arg.not.allowed");
759
760        Element e = env.trees.getElement(getCurrentPath());
761        if (e == null)
762            env.messages.error(REFERENCE, tree, "dc.ref.not.found");
763        return super.visitReference(tree, ignore);
764    }
765
766    @Override @DefinedBy(Api.COMPILER_TREE)
767    public Void visitReturn(ReturnTree tree, Void ignore) {
768        Element e = env.trees.getElement(env.currPath);
769        if (e.getKind() != ElementKind.METHOD
770                || ((ExecutableElement) e).getReturnType().getKind() == TypeKind.VOID)
771            env.messages.error(REFERENCE, tree, "dc.invalid.return");
772        foundReturn = true;
773        warnIfEmpty(tree, tree.getDescription());
774        return super.visitReturn(tree, ignore);
775    }
776
777    @Override @DefinedBy(Api.COMPILER_TREE)
778    public Void visitSerialData(SerialDataTree tree, Void ignore) {
779        warnIfEmpty(tree, tree.getDescription());
780        return super.visitSerialData(tree, ignore);
781    }
782
783    @Override @DefinedBy(Api.COMPILER_TREE)
784    public Void visitSerialField(SerialFieldTree tree, Void ignore) {
785        warnIfEmpty(tree, tree.getDescription());
786        return super.visitSerialField(tree, ignore);
787    }
788
789    @Override @DefinedBy(Api.COMPILER_TREE)
790    public Void visitSince(SinceTree tree, Void ignore) {
791        warnIfEmpty(tree, tree.getBody());
792        return super.visitSince(tree, ignore);
793    }
794
795    @Override @DefinedBy(Api.COMPILER_TREE)
796    public Void visitThrows(ThrowsTree tree, Void ignore) {
797        ReferenceTree exName = tree.getExceptionName();
798        Element ex = env.trees.getElement(new DocTreePath(getCurrentPath(), exName));
799        if (ex == null) {
800            env.messages.error(REFERENCE, tree, "dc.ref.not.found");
801        } else if (isThrowable(ex.asType())) {
802            switch (env.currElement.getKind()) {
803                case CONSTRUCTOR:
804                case METHOD:
805                    if (isCheckedException(ex.asType())) {
806                        ExecutableElement ee = (ExecutableElement) env.currElement;
807                        checkThrowsDeclared(exName, ex.asType(), ee.getThrownTypes());
808                    }
809                    break;
810                default:
811                    env.messages.error(REFERENCE, tree, "dc.invalid.throws");
812            }
813        } else {
814            env.messages.error(REFERENCE, tree, "dc.invalid.throws");
815        }
816        warnIfEmpty(tree, tree.getDescription());
817        return scan(tree.getDescription(), ignore);
818    }
819
820    private boolean isThrowable(TypeMirror tm) {
821        switch (tm.getKind()) {
822            case DECLARED:
823            case TYPEVAR:
824                return env.types.isAssignable(tm, env.java_lang_Throwable);
825        }
826        return false;
827    }
828
829    private void checkThrowsDeclared(ReferenceTree tree, TypeMirror t, List<? extends TypeMirror> list) {
830        boolean found = false;
831        for (TypeMirror tl : list) {
832            if (env.types.isAssignable(t, tl)) {
833                foundThrows.add(tl);
834                found = true;
835            }
836        }
837        if (!found)
838            env.messages.error(REFERENCE, tree, "dc.exception.not.thrown", t);
839    }
840
841    private void checkThrowsDocumented(List<? extends TypeMirror> list) {
842        if (foundInheritDoc)
843            return;
844
845        for (TypeMirror tl: list) {
846            if (isCheckedException(tl) && !foundThrows.contains(tl))
847                reportMissing("dc.missing.throws", tl);
848        }
849    }
850
851    @Override @DefinedBy(Api.COMPILER_TREE)
852    public Void visitUnknownBlockTag(UnknownBlockTagTree tree, Void ignore) {
853        checkUnknownTag(tree, tree.getTagName());
854        return super.visitUnknownBlockTag(tree, ignore);
855    }
856
857    @Override @DefinedBy(Api.COMPILER_TREE)
858    public Void visitUnknownInlineTag(UnknownInlineTagTree tree, Void ignore) {
859        checkUnknownTag(tree, tree.getTagName());
860        return super.visitUnknownInlineTag(tree, ignore);
861    }
862
863    private void checkUnknownTag(DocTree tree, String tagName) {
864        if (env.customTags != null && !env.customTags.contains(tagName))
865            env.messages.error(SYNTAX, tree, "dc.tag.unknown", tagName);
866    }
867
868    @Override @DefinedBy(Api.COMPILER_TREE)
869    public Void visitValue(ValueTree tree, Void ignore) {
870        ReferenceTree ref = tree.getReference();
871        if (ref == null || ref.getSignature().isEmpty()) {
872            if (!isConstant(env.currElement))
873                env.messages.error(REFERENCE, tree, "dc.value.not.allowed.here");
874        } else {
875            Element e = env.trees.getElement(new DocTreePath(getCurrentPath(), ref));
876            if (!isConstant(e))
877                env.messages.error(REFERENCE, tree, "dc.value.not.a.constant");
878        }
879
880        markEnclosingTag(Flag.HAS_INLINE_TAG);
881        return super.visitValue(tree, ignore);
882    }
883
884    private boolean isConstant(Element e) {
885        if (e == null)
886            return false;
887
888        switch (e.getKind()) {
889            case FIELD:
890                Object value = ((VariableElement) e).getConstantValue();
891                return (value != null); // can't distinguish "not a constant" from "constant is null"
892            default:
893                return false;
894        }
895    }
896
897    @Override @DefinedBy(Api.COMPILER_TREE)
898    public Void visitVersion(VersionTree tree, Void ignore) {
899        warnIfEmpty(tree, tree.getBody());
900        return super.visitVersion(tree, ignore);
901    }
902
903    @Override @DefinedBy(Api.COMPILER_TREE)
904    public Void visitErroneous(ErroneousTree tree, Void ignore) {
905        env.messages.error(SYNTAX, tree, null, tree.getDiagnostic().getMessage(null));
906        return null;
907    }
908    // </editor-fold>
909
910    // <editor-fold defaultstate="collapsed" desc="Utility methods">
911
912    private boolean isCheckedException(TypeMirror t) {
913        return !(env.types.isAssignable(t, env.java_lang_Error)
914                || env.types.isAssignable(t, env.java_lang_RuntimeException));
915    }
916
917    private boolean isSynthetic() {
918        switch (env.currElement.getKind()) {
919            case CONSTRUCTOR:
920                // A synthetic default constructor has the same pos as the
921                // enclosing class
922                TreePath p = env.currPath;
923                return env.getPos(p) == env.getPos(p.getParentPath());
924        }
925        return false;
926    }
927
928    void markEnclosingTag(Flag flag) {
929        TagStackItem top = tagStack.peek();
930        if (top != null)
931            top.flags.add(flag);
932    }
933
934    String toString(TreePath p) {
935        StringBuilder sb = new StringBuilder("TreePath[");
936        toString(p, sb);
937        sb.append("]");
938        return sb.toString();
939    }
940
941    void toString(TreePath p, StringBuilder sb) {
942        TreePath parent = p.getParentPath();
943        if (parent != null) {
944            toString(parent, sb);
945            sb.append(",");
946        }
947       sb.append(p.getLeaf().getKind()).append(":").append(env.getPos(p)).append(":S").append(env.getStartPos(p));
948    }
949
950    void warnIfEmpty(DocTree tree, List<? extends DocTree> list) {
951        for (DocTree d: list) {
952            switch (d.getKind()) {
953                case TEXT:
954                    if (hasNonWhitespace((TextTree) d))
955                        return;
956                    break;
957                default:
958                    return;
959            }
960        }
961        env.messages.warning(SYNTAX, tree, "dc.empty", tree.getKind().tagName);
962    }
963
964    boolean hasNonWhitespace(TextTree tree) {
965        String s = tree.getBody();
966        for (int i = 0; i < s.length(); i++) {
967            if (!Character.isWhitespace(s.charAt(i)))
968                return true;
969        }
970        return false;
971    }
972
973    // </editor-fold>
974
975}
976