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 }
87