libcxx/include/__locale_dir/locale_guard.h

   1 //===----------------------------------------------------------------------===//
   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 #ifndef _LIBCPP___LOCALE_DIR_LOCALE_GUARD_H
  10 #define _LIBCPP___LOCALE_DIR_LOCALE_GUARD_H
  11
  12 #include <__config>
  13 #include <__locale> // for locale_t
  14 #include <clocale>
  15
  16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  17 #  pragma GCC system_header
  18 #endif
  19
  20 _LIBCPP_BEGIN_NAMESPACE_STD
  21
  22 #if defined(_LIBCPP_MSVCRT_LIKE)
  23 struct __locale_guard {
  24   __locale_guard(locale_t __l) : __status(_configthreadlocale(_ENABLE_PER_THREAD_LOCALE)) {
  25     // Setting the locale can be expensive even when the locale given is
  26     // already the current locale, so do an explicit check to see if the
  27     // current locale is already the one we want.
  28     const char* __lc = __setlocale(nullptr);
  29     // If every category is the same, the locale string will simply be the
  30     // locale name, otherwise it will be a semicolon-separated string listing
  31     // each category.  In the second case, we know at least one category won't
  32     // be what we want, so we only have to check the first case.
  33     if (std::strcmp(__l.__get_locale(), __lc) != 0) {
  34       __locale_all = _strdup(__lc);
  35       if (__locale_all == nullptr)
  36         __throw_bad_alloc();
  37       __setlocale(__l.__get_locale());
  38     }
  39   }
  40   ~__locale_guard() {
  41     // The CRT documentation doesn't explicitly say, but setlocale() does the
  42     // right thing when given a semicolon-separated list of locale settings
  43     // for the different categories in the same format as returned by
  44     // setlocale(LC_ALL, nullptr).
  45     if (__locale_all != nullptr) {
  46       __setlocale(__locale_all);
  47       free(__locale_all);
  48     }
  49     _configthreadlocale(__status);
  50   }
  51   static const char* __setlocale(const char* __locale) {
  52     const char* __new_locale = setlocale(LC_ALL, __locale);
  53     if (__new_locale == nullptr)
  54       __throw_bad_alloc();
  55     return __new_locale;
  56   }
  57   int __status;
  58   char* __locale_all = nullptr;
  59 };
  60 #else
  61 struct __locale_guard {
  62   _LIBCPP_HIDE_FROM_ABI __locale_guard(locale_t& __loc) : __old_loc_(uselocale(__loc)) {}
  63
  64   _LIBCPP_HIDE_FROM_ABI ~__locale_guard() {
  65     if (__old_loc_)
  66       uselocale(__old_loc_);
  67   }
  68
  69   locale_t __old_loc_;
  70
  71   __locale_guard(__locale_guard const&)            = delete;
  72   __locale_guard& operator=(__locale_guard const&) = delete;
  73 };
  74 #endif
  75
  76 _LIBCPP_END_NAMESPACE_STD
  77
  78 #endif // _LIBCPP___LOCALE_DIR_LOCALE_GUARD_H