libcxx/test/std/strings/basic.string/string.capacity/empty.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 // bool empty() const noexcept; // 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   ASSERT_NOEXCEPT(s.empty());
  22   assert(s.empty() == (s.size() == 0));
  23 }
  24
  25 template <class S>
  26 TEST_CONSTEXPR_CXX20 void test_string() {
  27   test(S());
  28   test(S("123"));
  29   test(S("12345678901234567890123456789012345678901234567890"));
  30 }
  31
  32 TEST_CONSTEXPR_CXX20 bool test() {
  33   test_string<std::string>();
  34 #if TEST_STD_VER >= 11
  35   test_string<std::basic_string<char, std::char_traits<char>, min_allocator<char>>>();
  36 #endif
  37
  38   return true;
  39 }
  40
  41 int main(int, char**) {
  42   test();
  43 #if TEST_STD_VER > 17
  44   static_assert(test());
  45 #endif
  46
  47   return 0;
  48 }