libcxx/test/std/strings/basic.string/string.iterators/begin.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 //       iterator begin(); // constexpr since C++20
  12 // const_iterator begin() const; // 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(S s) {
  22   const S& cs                   = s;
  23   typename S::iterator b        = s.begin();
  24   typename S::const_iterator cb = cs.begin();
  25   if (!s.empty()) {
  26     assert(*b == s[0]);
  27   }
  28   assert(b == cb);
  29 }
  30
  31 template <class S>
  32 TEST_CONSTEXPR_CXX20 void test_string() {
  33   test(S());
  34   test(S("123"));
  35 }
  36
  37 TEST_CONSTEXPR_CXX20 bool test() {
  38   test_string<std::string>();
  39 #if TEST_STD_VER >= 11
  40   test_string<std::basic_string<char, std::char_traits<char>, min_allocator<char> > >();
  41 #endif
  42
  43   return true;
  44 }
  45
  46 int main(int, char**) {
  47   test();
  48 #if TEST_STD_VER > 17
  49   static_assert(test());
  50 #endif
  51
  52   return 0;
  53 }