libcxx/test/std/strings/basic.string/string.iterators/cbegin.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_iterator cbegin() const; // constexpr since C++20
  12
  13 #include <string>
  14 #include <cassert>
  15
  16 #include "test_macros.h"
  17 #include "min_allocator.h"
  18
  19 template <class S>
  20 TEST_CONSTEXPR_CXX20 void test(const S& s) {
  21   typename S::const_iterator cb = s.cbegin();
  22   if (!s.empty()) {
  23     assert(*cb == s[0]);
  24   }
  25   assert(cb == s.begin());
  26 }
  27
  28 template <class S>
  29 TEST_CONSTEXPR_CXX20 void test_string() {
  30   test(S());
  31   test(S("123"));
  32 }
  33
  34 TEST_CONSTEXPR_CXX20 bool test() {
  35   test_string<std::string>();
  36 #if TEST_STD_VER >= 11
  37   test_string<std::basic_string<char, std::char_traits<char>, min_allocator<char> > >();
  38 #endif
  39
  40   return true;
  41 }
  42
  43 int main(int, char**) {
  44   test();
  45 #if TEST_STD_VER > 17
  46   static_assert(test());
  47 #endif
  48
  49   return 0;
  50 }