libcxx/test/std/strings/basic.string/string.capacity/shrink_to_fit.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 // void shrink_to_fit(); // 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(S s) {
  21   typename S::size_type old_cap = s.capacity();
  22   S s0                          = s;
  23   s.shrink_to_fit();
  24   LIBCPP_ASSERT(s.__invariants());
  25   assert(s == s0);
  26   assert(s.capacity() <= old_cap);
  27   assert(s.capacity() >= s.size());
  28 }
  29
  30 template <class S>
  31 TEST_CONSTEXPR_CXX20 void test_string() {
  32   S s;
  33   test(s);
  34
  35   s.assign(10, 'a');
  36   s.erase(5);
  37   test(s);
  38
  39   s.assign(100, 'a');
  40   s.erase(50);
  41   test(s);
  42 }
  43
  44 TEST_CONSTEXPR_CXX20 bool test() {
  45   test_string<std::string>();
  46 #if TEST_STD_VER >= 11
  47   test_string<std::basic_string<char, std::char_traits<char>, min_allocator<char>>>();
  48 #endif
  49
  50   return true;
  51 }
  52
  53 int main(int, char**) {
  54   test();
  55 #if TEST_STD_VER > 17
  56   static_assert(test());
  57 #endif
  58
  59   return 0;
  60 }