1 //===--- NamespaceCommentCheck.cpp - clang-tidy ---------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "NamespaceCommentCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchers.h"
13 #include "clang/Lex/Lexer.h"
14 #include "llvm/ADT/StringExtras.h"
15 
16 using namespace clang::ast_matchers;
17 
18 namespace clang {
19 namespace tidy {
20 namespace readability {
21 
22 NamespaceCommentCheck::NamespaceCommentCheck(StringRef Name,
23                                              ClangTidyContext *Context)
24     : ClangTidyCheck(Name, Context),
25       NamespaceCommentPattern("^/[/*] *(end (of )?)? *(anonymous|unnamed)? *"
26                               "namespace( +([a-zA-Z0-9_]+))?\\.? *(\\*/)?$",
27                               llvm::Regex::IgnoreCase),
28       ShortNamespaceLines(Options.get("ShortNamespaceLines", 1u)),
29       SpacesBeforeComments(Options.get("SpacesBeforeComments", 1u)) {}
30 
31 void NamespaceCommentCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
32   Options.store(Opts, "ShortNamespaceLines", ShortNamespaceLines);
33   Options.store(Opts, "SpacesBeforeComments", SpacesBeforeComments);
34 }
35 
36 void NamespaceCommentCheck::registerMatchers(MatchFinder *Finder) {
37   // Only register the matchers for C++; the functionality currently does not
38   // provide any benefit to other languages, despite being benign.
39   if (getLangOpts().CPlusPlus)
40     Finder->addMatcher(namespaceDecl().bind("namespace"), this);
41 }
42 
43 static bool locationsInSameFile(const SourceManager &Sources,
44                                 SourceLocation Loc1, SourceLocation Loc2) {
45   return Loc1.isFileID() && Loc2.isFileID() &&
46          Sources.getFileID(Loc1) == Sources.getFileID(Loc2);
47 }
48 
49 static std::string getNamespaceComment(const NamespaceDecl *ND,
50                                        bool InsertLineBreak) {
51   std::string Fix = "// namespace";
52   if (!ND->isAnonymousNamespace())
53     Fix.append(" ").append(ND->getNameAsString());
54   if (InsertLineBreak)
55     Fix.append("\n");
56   return Fix;
57 }
58 
59 void NamespaceCommentCheck::check(const MatchFinder::MatchResult &Result) {
60   const NamespaceDecl *ND = Result.Nodes.getNodeAs<NamespaceDecl>("namespace");
61   const SourceManager &Sources = *Result.SourceManager;
62 
63   if (!locationsInSameFile(Sources, ND->getLocStart(), ND->getRBraceLoc()))
64     return;
65 
66   // Don't require closing comments for namespaces spanning less than certain
67   // number of lines.
68   unsigned StartLine = Sources.getSpellingLineNumber(ND->getLocStart());
69   unsigned EndLine = Sources.getSpellingLineNumber(ND->getRBraceLoc());
70   if (EndLine - StartLine + 1 <= ShortNamespaceLines)
71     return;
72 
73   // Find next token after the namespace closing brace.
74   SourceLocation AfterRBrace = ND->getRBraceLoc().getLocWithOffset(1);
75   SourceLocation Loc = AfterRBrace;
76   Token Tok;
77   // Skip whitespace until we find the next token.
78   while (Lexer::getRawToken(Loc, Tok, Sources, Result.Context->getLangOpts())) {
79     Loc = Loc.getLocWithOffset(1);
80   }
81   if (!locationsInSameFile(Sources, ND->getRBraceLoc(), Loc))
82     return;
83 
84   bool NextTokenIsOnSameLine = Sources.getSpellingLineNumber(Loc) == EndLine;
85   // If we insert a line comment before the token in the same line, we need
86   // to insert a line break.
87   bool NeedLineBreak = NextTokenIsOnSameLine && Tok.isNot(tok::eof);
88 
89   SourceRange OldCommentRange(AfterRBrace, AfterRBrace);
90   std::string Message = "%0 not terminated with a closing comment";
91 
92   // Try to find existing namespace closing comment on the same line.
93   if (Tok.is(tok::comment) && NextTokenIsOnSameLine) {
94     StringRef Comment(Sources.getCharacterData(Loc), Tok.getLength());
95     SmallVector<StringRef, 7> Groups;
96     if (NamespaceCommentPattern.match(Comment, &Groups)) {
97       StringRef NamespaceNameInComment = Groups.size() > 5 ? Groups[5] : "";
98       StringRef Anonymous = Groups.size() > 3 ? Groups[3] : "";
99 
100       // Check if the namespace in the comment is the same.
101       if ((ND->isAnonymousNamespace() && NamespaceNameInComment.empty()) ||
102           (ND->getNameAsString() == NamespaceNameInComment &&
103            Anonymous.empty())) {
104         // FIXME: Maybe we need a strict mode, where we always fix namespace
105         // comments with different format.
106         return;
107       }
108 
109       // Otherwise we need to fix the comment.
110       NeedLineBreak = Comment.startswith("/*");
111       OldCommentRange =
112           SourceRange(AfterRBrace, Loc.getLocWithOffset(Tok.getLength()));
113       Message =
114           (llvm::Twine(
115                "%0 ends with a comment that refers to a wrong namespace '") +
116            NamespaceNameInComment + "'").str();
117     } else if (Comment.startswith("//")) {
118       // Assume that this is an unrecognized form of a namespace closing line
119       // comment. Replace it.
120       NeedLineBreak = false;
121       OldCommentRange =
122           SourceRange(AfterRBrace, Loc.getLocWithOffset(Tok.getLength()));
123       Message = "%0 ends with an unrecognized comment";
124     }
125     // If it's a block comment, just move it to the next line, as it can be
126     // multi-line or there may be other tokens behind it.
127   }
128 
129   std::string NamespaceName =
130       ND->isAnonymousNamespace()
131           ? "anonymous namespace"
132           : ("namespace '" + ND->getNameAsString() + "'");
133 
134   diag(AfterRBrace, Message)
135       << NamespaceName << FixItHint::CreateReplacement(
136                               CharSourceRange::getCharRange(OldCommentRange),
137                               std::string(SpacesBeforeComments, ' ') +
138                                   getNamespaceComment(ND, NeedLineBreak));
139   diag(ND->getLocation(), "%0 starts here", DiagnosticIDs::Note)
140       << NamespaceName;
141 }
142 
143 } // namespace readability
144 } // namespace tidy
145 } // namespace clang
146