1//===----------------------------------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is dual licensed under the MIT and the University of Illinois Open
6// Source Licenses. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10// <istream>
11
12// int_type peek();
13
14#include <istream>
15#include <cassert>
16
17template <class CharT>
18struct testbuf
19    : public std::basic_streambuf<CharT>
20{
21    typedef std::basic_string<CharT> string_type;
22    typedef std::basic_streambuf<CharT> base;
23private:
24    string_type str_;
25public:
26
27    testbuf() {}
28    testbuf(const string_type& str)
29        : str_(str)
30    {
31        base::setg(const_cast<CharT*>(str_.data()),
32                   const_cast<CharT*>(str_.data()),
33                   const_cast<CharT*>(str_.data()) + str_.size());
34    }
35
36    CharT* eback() const {return base::eback();}
37    CharT* gptr() const {return base::gptr();}
38    CharT* egptr() const {return base::egptr();}
39};
40
41int main()
42{
43    {
44        testbuf<char> sb(" 1\n2345\n6");
45        std::istream is(&sb);
46        assert(is.peek() == ' ');
47        assert(!is.eof());
48        assert(!is.fail());
49        assert(is.gcount() == 0);
50        is.get();
51        assert(is.peek() == '1');
52        assert(!is.eof());
53        assert(!is.fail());
54        assert(is.gcount() == 0);
55    }
56    {
57        testbuf<wchar_t> sb(L" 1\n2345\n6");
58        std::wistream is(&sb);
59        assert(is.peek() == L' ');
60        assert(!is.eof());
61        assert(!is.fail());
62        assert(is.gcount() == 0);
63        is.get();
64        assert(is.peek() == L'1');
65        assert(!is.eof());
66        assert(!is.fail());
67        assert(is.gcount() == 0);
68    }
69}
70