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 // UNSUPPORTED: c++98, c++03
  10
  11 // <istream>
  12
  13 // template <class charT, class traits, class T>
  14 //   basic_istream<charT, traits>&
  15 //   operator>>(basic_istream<charT, traits>&& is, T&& x);
  16
  17 #include <istream>
  18 #include <sstream>
  19 #include <cassert>
  20
  21 #include "test_macros.h"
  22
  23 template <class CharT>
  24 struct testbuf
  25     : public std::basic_streambuf<CharT>
  26 {
  27     typedef std::basic_string<CharT> string_type;
  28     typedef std::basic_streambuf<CharT> base;
  29 private:
  30     string_type str_;
  31 public:
  32
  33     testbuf() {}
  34     testbuf(const string_type& str)
  35         : str_(str)
  36     {
  37         base::setg(const_cast<CharT*>(str_.data()),
  38                    const_cast<CharT*>(str_.data()),
  39                    const_cast<CharT*>(str_.data()) + str_.size());
  40     }
  41
  42     CharT* eback() const {return base::eback();}
  43     CharT* gptr() const {return base::gptr();}
  44     CharT* egptr() const {return base::egptr();}
  45 };
  46
  47
  48 struct A{};
  49 bool called = false;
  50 void operator>>(std::istream&, A&&){ called = true; }
  51
  52 int main(int, char**)
  53 {
  54     {
  55         testbuf<char> sb("   123");
  56         int i = 0;
  57         std::istream(&sb) >> i;
  58         assert(i == 123);
  59     }
  60     {
  61         testbuf<wchar_t> sb(L"   123");
  62         int i = 0;
  63         std::wistream(&sb) >> i;
  64         assert(i == 123);
  65     }
  66     { // test perfect forwarding
  67         assert(called == false);
  68         std::istringstream ss;
  69         auto&& out = (std::move(ss) >> A{});
  70         assert(&out == &ss);
  71         assert(called);
  72     }
  73
  74   return 0;
  75 }