libcxx/test/std/input.output/syncstream/osyncstream/assign.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 // UNSUPPORTED: c++03, c++11, c++14, c++17
  10 // UNSUPPORTED: no-localization
  11 // UNSUPPORTED: libcpp-has-no-experimental-syncstream
  12
  13 // <syncstream>
  14
  15 // template <class charT, class traits, class Allocator>
  16 // class basic_osyncstream;
  17
  18 // basic_osyncstream& operator=(basic_osyncstream&& rhs);
  19
  20 #include <syncstream>
  21 #include <sstream>
  22 #include <cassert>
  23
  24 #include "test_macros.h"
  25 #include "test_allocator.h"
  26
  27 template <class CharT, bool propagate>
  28 static void test() {
  29   using Traits    = std::char_traits<CharT>;
  30   using Allocator = std::conditional_t<propagate, other_allocator<CharT>, test_allocator<CharT>>;
  31   static_assert(std::allocator_traits<Allocator>::propagate_on_container_move_assignment::value == propagate);
  32
  33   using OS = std::basic_osyncstream<CharT, Traits, Allocator>;
  34
  35   std::basic_stringbuf<CharT, Traits, Allocator> base1;
  36   std::basic_stringbuf<CharT, Traits, Allocator> base2;
  37
  38   {
  39     OS out1{&base1, Allocator{42}};
  40     assert(out1.get_wrapped() == &base1);
  41
  42     typename OS::syncbuf_type* sb1 = out1.rdbuf();
  43     assert(sb1->get_wrapped() == &base1);
  44     assert(sb1->get_allocator().get_data() == 42);
  45
  46     out1 << CharT('A');
  47
  48     static_assert(!noexcept(out1.operator=(std::move(out1)))); // LWG-3867
  49     OS out2{&base2, Allocator{99}};
  50
  51     out2 << CharT('Z');
  52
  53     // Validate the data is still in the syncbuf and not in the stringbuf.
  54     assert(base1.str().empty());
  55     assert(base2.str().empty());
  56
  57     out2 = std::move(out1);
  58
  59     // Since sb2 is overwritten by the move its data should be in its stringbuf.
  60     assert(base1.str().empty());
  61     assert(base2.str().size() == 1);
  62     assert(base2.str()[0] == CharT('Z'));
  63
  64     assert(out2.get_wrapped() == &base1);
  65
  66     typename OS::syncbuf_type* sb2 = out2.rdbuf();
  67     assert(sb2->get_wrapped() == &base1);
  68     if constexpr (std::allocator_traits<Allocator>::propagate_on_container_move_assignment::value)
  69       assert(sb2->get_allocator().get_data() == 42);
  70     else
  71       assert(sb2->get_allocator().get_data() == 99);
  72
  73     assert(out1.get_wrapped() == nullptr);
  74     assert(sb1->get_wrapped() == nullptr);
  75
  76     // The data written to 2 will be stored in sb1. The write happens after the destruction.
  77     out2 << CharT('B');
  78     assert(base1.str().empty());
  79   }
  80
  81   assert(base1.str().size() == 2);
  82   assert(base1.str()[0] == CharT('A'));
  83   assert(base1.str()[1] == CharT('B'));
  84   assert(base2.str().size() == 1);
  85   assert(base2.str()[0] == CharT('Z'));
  86 }
  87
  88 template <class CharT>
  89 static void test() {
  90   test<CharT, true>();
  91   test<CharT, false>();
  92 }
  93
  94 int main(int, char**) {
  95   test<char>();
  96 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  97   test<wchar_t>();
  98 #endif
  99
 100   return 0;
 101 }