1 //===--- GlobalVariableDeclarationCheck.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 "GlobalVariableDeclarationCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "llvm/ADT/StringExtras.h"
14 #include "llvm/ADT/StringRef.h"
15 
16 #include <string>
17 
18 using namespace clang::ast_matchers;
19 
20 namespace clang {
21 namespace tidy {
22 namespace google {
23 namespace objc {
24 
25 namespace {
26 
27 AST_MATCHER(VarDecl, isLocalVariable) {
28   return Node.isLocalVarDecl();
29 }
30 
31 FixItHint generateFixItHint(const VarDecl *Decl, bool IsConst) {
32   char FC = Decl->getName()[0];
33   if (!llvm::isAlpha(FC) || Decl->getName().size() == 1) {
34     // No fix available if first character is not alphabetical character, or it
35     // is a single-character variable, since it is difficult to determine the
36     // proper fix in this case. Users should create a proper variable name by
37     // their own.
38     return FixItHint();
39   }
40   char SC = Decl->getName()[1];
41   if ((FC == 'k' || FC == 'g') && !llvm::isAlpha(SC)) {
42     // No fix available if the prefix is correct but the second character is not
43     // alphabetical, since it is difficult to determine the proper fix in this
44     // case.
45     return FixItHint();
46   }
47   auto NewName = (IsConst ? "k" : "g") +
48                  llvm::StringRef(std::string(1, FC)).upper() +
49                  Decl->getName().substr(1).str();
50   return FixItHint::CreateReplacement(
51       CharSourceRange::getTokenRange(SourceRange(Decl->getLocation())),
52       llvm::StringRef(NewName));
53 }
54 }  // namespace
55 
56 void GlobalVariableDeclarationCheck::registerMatchers(MatchFinder *Finder) {
57   // The relevant Style Guide rule only applies to Objective-C.
58   if (!getLangOpts().ObjC1 && !getLangOpts().ObjC2) {
59     return;
60   }
61   // need to add two matchers since we need to bind different ids to distinguish
62   // constants and variables. Since bind() can only be called on node matchers,
63   // we cannot make it in one matcher.
64   //
65   // Note that hasGlobalStorage() matches static variables declared locally
66   // inside a function or method, so we need to exclude those with
67   // isLocalVariable().
68   Finder->addMatcher(
69       varDecl(hasGlobalStorage(), unless(hasType(isConstQualified())),
70               unless(isLocalVariable()), unless(matchesName("::g[A-Z]")))
71           .bind("global_var"),
72       this);
73   Finder->addMatcher(varDecl(hasGlobalStorage(), hasType(isConstQualified()),
74                              unless(isLocalVariable()),
75                              unless(matchesName("::k[A-Z]")))
76                          .bind("global_const"),
77                      this);
78 }
79 
80 void GlobalVariableDeclarationCheck::check(
81     const MatchFinder::MatchResult &Result) {
82   if (const auto *Decl = Result.Nodes.getNodeAs<VarDecl>("global_var")) {
83     diag(Decl->getLocation(),
84          "non-const global variable '%0' must have a name which starts with "
85          "'g[A-Z]'")
86         << Decl->getName() << generateFixItHint(Decl, false);
87   }
88   if (const auto *Decl = Result.Nodes.getNodeAs<VarDecl>("global_const")) {
89     diag(Decl->getLocation(),
90          "const global variable '%0' must have a name which starts with "
91          "'k[A-Z]'")
92         << Decl->getName() << generateFixItHint(Decl, true);
93   }
94 }
95 
96 }  // namespace objc
97 }  // namespace google
98 }  // namespace tidy
99 }  // namespace clang
100