libcxx/test/support/string_literal.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 SUPPORT_TEST_STRING_LITERAL_H
  10 #define SUPPORT_TEST_STRING_LITERAL_H
  11
  12 #include "test_macros.h"
  13
  14 #include <algorithm>
  15 #include <concepts>
  16 #include <string_view>
  17
  18 #if TEST_STD_VER > 17
  19
  20 /// Helper class to "transfer" a string literal
  21 ///
  22 /// The MAKE_STRING helper macros turn a string literal into a const char*.
  23 /// This is an issue when testing std::format; its format-string needs a string
  24 /// literal for compile-time validation. This class does the job.
  25 ///
  26 /// \note The class assumes a wchar_t can be initialized from a char.
  27 /// \note All members are public to avoid compilation errors.
  28 template <std::size_t N>
  29 struct string_literal {
  30   consteval /*implicit*/ string_literal(const char (&str)[N + 1]) {
  31     std::copy_n(str, N + 1, data_);
  32 #  ifndef TEST_HAS_NO_WIDE_CHARACTERS
  33     std::copy_n(str, N + 1, wdata_);
  34 #  endif
  35   }
  36
  37   template <class CharT>
  38   consteval std::basic_string_view<CharT> sv() const {
  39     if constexpr (std::same_as<CharT, char>)
  40       return std::basic_string_view{data_};
  41 #  ifndef TEST_HAS_NO_WIDE_CHARACTERS
  42     else
  43       return std::basic_string_view{wdata_};
  44 #  endif
  45   }
  46
  47   char data_[N + 1];
  48 #  ifndef TEST_HAS_NO_WIDE_CHARACTERS
  49   wchar_t wdata_[N + 1];
  50 #  endif
  51 };
  52
  53 template <std::size_t N>
  54 string_literal(const char (&str)[N]) -> string_literal<N - 1>;
  55
  56 #endif // TEST_STD_VER > 17
  57
  58 #endif // SUPPORT_TEST_STRING_LITERAL_H