libcxx/test/std/strings/basic.string/string.capacity/capacity.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 // size_type capacity() const; // constexpr since C++20
  12
  13 #include <string>
  14 #include <cassert>
  15
  16 #include "test_allocator.h"
  17 #include "min_allocator.h"
  18
  19 #include "test_macros.h"
  20
  21 template <class S>
  22 TEST_CONSTEXPR_CXX20 void test_invariant(S s, test_allocator_statistics& alloc_stats) {
  23   alloc_stats.throw_after = 0;
  24 #ifndef TEST_HAS_NO_EXCEPTIONS
  25   try
  26 #endif
  27   {
  28     while (s.size() < s.capacity())
  29       s.push_back(typename S::value_type());
  30     assert(s.size() == s.capacity());
  31   }
  32 #ifndef TEST_HAS_NO_EXCEPTIONS
  33   catch (...) {
  34     assert(false);
  35   }
  36 #endif
  37   alloc_stats.throw_after = INT_MAX;
  38 }
  39
  40 template <class Alloc>
  41 TEST_CONSTEXPR_CXX20 void test_string(const Alloc& a) {
  42   using S = std::basic_string<char, std::char_traits<char>, Alloc>;
  43   {
  44     S const s((Alloc(a)));
  45     assert(s.capacity() >= 0);
  46   }
  47   {
  48     S const s(3, 'x', Alloc(a));
  49     assert(s.capacity() >= 3);
  50   }
  51 #if TEST_STD_VER >= 11
  52   // Check that we perform SSO
  53   {
  54     S const s;
  55     assert(s.capacity() > 0);
  56     ASSERT_NOEXCEPT(s.capacity());
  57   }
  58 #endif
  59 }
  60
  61 TEST_CONSTEXPR_CXX20 bool test() {
  62   test_string(std::allocator<char>());
  63   test_string(test_allocator<char>());
  64   test_string(test_allocator<char>(3));
  65   test_string(min_allocator<char>());
  66
  67   {
  68     test_allocator_statistics alloc_stats;
  69     typedef std::basic_string<char, std::char_traits<char>, test_allocator<char> > S;
  70     S s((test_allocator<char>(&alloc_stats)));
  71     test_invariant(s, alloc_stats);
  72     s.assign(10, 'a');
  73     s.erase(5);
  74     test_invariant(s, alloc_stats);
  75     s.assign(100, 'a');
  76     s.erase(50);
  77     test_invariant(s, alloc_stats);
  78   }
  79
  80   return true;
  81 }
  82
  83 int main(int, char**) {
  84   test();
  85 #if TEST_STD_VER >= 20
  86   static_assert(test());
  87 #endif
  88
  89   return 0;
  90 }