libcxx/test/std/input.output/iostream.format/input.streams/istream.rvalue/rvalue.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 // <istream>
  10
  11 // template <class Stream, class T>
  12 // Stream&& operator>>(Stream&& is, T&& x);
  13
  14 #include <istream>
  15 #include <sstream>
  16 #include <cassert>
  17
  18 #include "test_macros.h"
  19
  20 template <class CharT>
  21 struct testbuf
  22     : public std::basic_streambuf<CharT>
  23 {
  24     typedef std::basic_string<CharT> string_type;
  25     typedef std::basic_streambuf<CharT> base;
  26 private:
  27     string_type str_;
  28 public:
  29
  30     testbuf() {}
  31     testbuf(const string_type& str)
  32         : str_(str)
  33     {
  34         base::setg(const_cast<CharT*>(str_.data()),
  35                    const_cast<CharT*>(str_.data()),
  36                    const_cast<CharT*>(str_.data()) + str_.size());
  37     }
  38
  39     CharT* eback() const {return base::eback();}
  40     CharT* gptr() const {return base::gptr();}
  41     CharT* egptr() const {return base::egptr();}
  42 };
  43
  44 struct Int {
  45     int value;
  46     template <class CharT>
  47     friend void operator>>(std::basic_istream<CharT>& is, Int& self) {
  48         is >> self.value;
  49     }
  50 };
  51
  52 struct A { };
  53 bool called = false;
  54 void operator>>(std::istream&, A&&) { called = true; }
  55
  56 int main(int, char**)
  57 {
  58     {
  59         testbuf<char> sb("   123");
  60         Int i = {0};
  61         std::istream is(&sb);
  62         std::istream&& result = (std::move(is) >> i);
  63         assert(&result == &is);
  64         assert(i.value == 123);
  65     }
  66 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  67     {
  68         testbuf<wchar_t> sb(L"   123");
  69         Int i = {0};
  70         std::wistream is(&sb);
  71         std::wistream&& result = (std::move(is) >> i);
  72         assert(&result == &is);
  73         assert(i.value == 123);
  74     }
  75 #endif
  76     {
  77         // test perfect forwarding
  78         assert(called == false);
  79         std::istringstream ss;
  80         std::istringstream&& result = (std::move(ss) >> A());
  81         assert(&result == &ss);
  82         assert(called);
  83     }
  84
  85     return 0;
  86 }