libcxx/test/std/strings/basic.string/string.access/index.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 // <string>
  10
  11 // const_reference operator[](size_type pos) const; // constexpr since C++20
  12 //       reference operator[](size_type pos); // constexpr since C++20
  13
  14 #include <string>
  15 #include <cassert>
  16
  17 #include "test_macros.h"
  18 #include "min_allocator.h"
  19
  20 template <class S>
  21 TEST_CONSTEXPR_CXX20 void test_string() {
  22   S s("0123456789");
  23   const S& cs = s;
  24   ASSERT_SAME_TYPE(decltype(s[0]), typename S::reference);
  25   ASSERT_SAME_TYPE(decltype(cs[0]), typename S::const_reference);
  26   LIBCPP_ASSERT_NOEXCEPT(s[0]);
  27   LIBCPP_ASSERT_NOEXCEPT(cs[0]);
  28   for (typename S::size_type i = 0; i < cs.size(); ++i) {
  29     assert(s[i] == static_cast<char>('0' + i));
  30     assert(cs[i] == s[i]);
  31   }
  32   assert(cs[cs.size()] == '\0');
  33   const S s2 = S();
  34   assert(s2[0] == '\0');
  35 }
  36
  37 // Same, but for the string that doesn't fit into SSO.
  38 template <class S>
  39 TEST_CONSTEXPR_CXX20 void test_string_long() {
  40   S s("0123456789012345678901234567890123456789");
  41   const S& cs = s;
  42   ASSERT_SAME_TYPE(decltype(s[0]), typename S::reference);
  43   ASSERT_SAME_TYPE(decltype(cs[0]), typename S::const_reference);
  44   LIBCPP_ASSERT_NOEXCEPT(s[0]);
  45   LIBCPP_ASSERT_NOEXCEPT(cs[0]);
  46   for (typename S::size_type i = 0; i < cs.size(); ++i) {
  47     assert(s[i] == static_cast<char>('0' + (i % 10)));
  48     assert(cs[i] == s[i]);
  49   }
  50   assert(s[33] == static_cast<char>('0' + (33 % 10)));
  51   assert(cs[34] == s[34]);
  52   assert(cs[cs.size()] == '\0');
  53   const S s2 = S();
  54   assert(s2[0] == '\0');
  55 }
  56
  57 TEST_CONSTEXPR_CXX20 bool test() {
  58   test_string<std::string>();
  59 #if TEST_STD_VER >= 11
  60   test_string<std::basic_string<char, std::char_traits<char>, min_allocator<char>>>();
  61   test_string_long<std::basic_string<char, std::char_traits<char>, min_allocator<char>>>();
  62 #endif
  63
  64   return true;
  65 }
  66
  67 int main(int, char**) {
  68   test();
  69 #if TEST_STD_VER > 17
  70   static_assert(test());
  71 #endif
  72
  73   return 0;
  74 }