libcxx/test/std/strings/string.view/string.view.access/front.pass.cpp

   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 // UNSUPPORTED: !stdlib=libc++ && (c++03 || c++11 || c++14)
  10
  11 // <string_view>
  12
  13 // constexpr const _CharT& back();
  14
  15 #include <string_view>
  16 #include <cassert>
  17
  18 #include "test_macros.h"
  19
  20 template <typename CharT>
  21 bool test(const CharT* s, std::size_t len) {
  22   typedef std::basic_string_view<CharT> SV;
  23   SV sv(s, len);
  24   ASSERT_SAME_TYPE(decltype(sv.front()), typename SV::const_reference);
  25   LIBCPP_ASSERT_NOEXCEPT(sv.front());
  26   assert(sv.length() == len);
  27   assert(sv.front() == s[0]);
  28   return &sv.front() == s;
  29 }
  30
  31 int main(int, char**) {
  32   assert(test("ABCDE", 5));
  33   assert(test("a", 1));
  34
  35 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  36   assert(test(L"ABCDE", 5));
  37   assert(test(L"a", 1));
  38 #endif
  39
  40 #if TEST_STD_VER >= 11
  41   assert(test(u"ABCDE", 5));
  42   assert(test(u"a", 1));
  43
  44   assert(test(U"ABCDE", 5));
  45   assert(test(U"a", 1));
  46 #endif
  47
  48 #if TEST_STD_VER >= 11
  49   {
  50     constexpr std::basic_string_view<char> sv("ABC", 2);
  51     static_assert(sv.length() == 2, "");
  52     static_assert(sv.front() == 'A', "");
  53   }
  54 #endif
  55
  56   return 0;
  57 }