clang-tools-extra/clang-tidy/objc/NSDateFormatterCheck.cpp

   1 //===--- NSDateFormatterCheck.cpp - clang-tidy ----------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "NSDateFormatterCheck.h"
  10 #include "clang/AST/ASTContext.h"
  11 #include "clang/ASTMatchers/ASTMatchFinder.h"
  12 #include "clang/ASTMatchers/ASTMatchers.h"
  13
  14 using namespace clang::ast_matchers;
  15
  16 namespace clang::tidy::objc {
  17
  18 void NSDateFormatterCheck::registerMatchers(MatchFinder *Finder) {
  19   // Adding matchers.
  20
  21   Finder->addMatcher(
  22       objcMessageExpr(hasSelector("setDateFormat:"),
  23                       hasReceiverType(asString("NSDateFormatter *")),
  24                       hasArgument(0, ignoringImpCasts(
  25                                          objcStringLiteral().bind("str_lit")))),
  26       this);
  27 }
  28
  29 static char ValidDatePatternChars[] = {
  30     'G', 'y', 'Y', 'u', 'U', 'r', 'Q', 'q', 'M', 'L', 'I', 'w', 'W', 'd',
  31     'D', 'F', 'g', 'E', 'e', 'c', 'a', 'b', 'B', 'h', 'H', 'K', 'k', 'j',
  32     'J', 'C', 'm', 's', 'S', 'A', 'z', 'Z', 'O', 'v', 'V', 'X', 'x'};
  33
  34 // Checks if the string pattern used as a date format specifier is valid.
  35 // A string pattern is valid if all the letters(a-z, A-Z) in it belong to the
  36 // set of reserved characters. See:
  37 // https://www.unicode.org/reports/tr35/tr35.html#Invalid_Patterns
  38 bool isValidDatePattern(StringRef Pattern) {
  39   return llvm::all_of(Pattern, [](const auto &PatternChar) {
  40     return !isalpha(PatternChar) ||
  41            llvm::is_contained(ValidDatePatternChars, PatternChar);
  42   });
  43 }
  44
  45 // Checks if the string pattern used as a date format specifier contains
  46 // any incorrect pattern and reports it as a warning.
  47 // See: http://www.unicode.org/reports/tr35/tr35-dates.html#Date_Format_Patterns
  48 void NSDateFormatterCheck::check(const MatchFinder::MatchResult &Result) {
  49   // Callback implementation.
  50   const auto *StrExpr = Result.Nodes.getNodeAs<ObjCStringLiteral>("str_lit");
  51   const StringLiteral *SL = cast<ObjCStringLiteral>(StrExpr)->getString();
  52   StringRef SR = SL->getString();
  53
  54   if (!isValidDatePattern(SR)) {
  55     diag(StrExpr->getExprLoc(), "invalid date format specifier");
  56   }
  57
  58   if (SR.contains('y') && SR.contains('w') && !SR.contains('Y')) {
  59     diag(StrExpr->getExprLoc(),
  60          "use of calendar year (y) with week of the year (w); "
  61          "did you mean to use week-year (Y) instead?");
  62   }
  63   if (SR.contains('F')) {
  64     if (!(SR.contains('e') || SR.contains('E'))) {
  65       diag(StrExpr->getExprLoc(),
  66            "day of week in month (F) used without day of the week (e or E); "
  67            "did you forget e (or E) in the format string?");
  68     }
  69     if (!SR.contains('M')) {
  70       diag(StrExpr->getExprLoc(),
  71            "day of week in month (F) used without the month (M); "
  72            "did you forget M in the format string?");
  73     }
  74   }
  75   if (SR.contains('W') && !SR.contains('M')) {
  76     diag(StrExpr->getExprLoc(), "Week of Month (W) used without the month (M); "
  77                                 "did you forget M in the format string?");
  78   }
  79   if (SR.contains('Y') && SR.contains('Q') && !SR.contains('y')) {
  80     diag(StrExpr->getExprLoc(),
  81          "use of week year (Y) with quarter number (Q); "
  82          "did you mean to use calendar year (y) instead?");
  83   }
  84   if (SR.contains('Y') && SR.contains('M') && !SR.contains('y')) {
  85     diag(StrExpr->getExprLoc(),
  86          "use of week year (Y) with month (M); "
  87          "did you mean to use calendar year (y) instead?");
  88   }
  89   if (SR.contains('Y') && SR.contains('D') && !SR.contains('y')) {
  90     diag(StrExpr->getExprLoc(),
  91          "use of week year (Y) with day of the year (D); "
  92          "did you mean to use calendar year (y) instead?");
  93   }
  94   if (SR.contains('Y') && SR.contains('W') && !SR.contains('y')) {
  95     diag(StrExpr->getExprLoc(),
  96          "use of week year (Y) with week of the month (W); "
  97          "did you mean to use calendar year (y) instead?");
  98   }
  99   if (SR.contains('Y') && SR.contains('F') && !SR.contains('y')) {
 100     diag(StrExpr->getExprLoc(),
 101          "use of week year (Y) with day of the week in month (F); "
 102          "did you mean to use calendar year (y) instead?");
 103   }
 104 }
 105
 106 } // namespace clang::tidy::objc