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      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 // streamsize readsome(char_type* s, streamsize n);
     13 
     14 #include <istream>
     15 #include <cassert>
     16 
     17 template <class CharT>
     18 struct testbuf
     19     : public std::basic_streambuf<CharT>
     20 {
     21     typedef std::basic_string<CharT> string_type;
     22     typedef std::basic_streambuf<CharT> base;
     23 private:
     24     string_type str_;
     25 public:
     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 
     41 int main()
     42 {
     43     {
     44         testbuf<char> sb(" 1234567890");
     45         std::istream is(&sb);
     46         char s[5];
     47         assert(is.readsome(s, 5) == 5);
     48         assert(!is.eof());
     49         assert(!is.fail());
     50         assert(std::string(s, 5) == " 1234");
     51         assert(is.gcount() == 5);
     52         is.readsome(s, 5);
     53         assert(!is.eof());
     54         assert(!is.fail());
     55         assert(std::string(s, 5) == "56789");
     56         assert(is.gcount() == 5);
     57         is.readsome(s, 5);
     58         assert(!is.eof());
     59         assert(!is.fail());
     60         assert(is.gcount() == 1);
     61         assert(std::string(s, 1) == "0");
     62         assert(is.readsome(s, 5) == 0);
     63     }
     64     {
     65         testbuf<wchar_t> sb(L" 1234567890");
     66         std::wistream is(&sb);
     67         wchar_t s[5];
     68         assert(is.readsome(s, 5) == 5);
     69         assert(!is.eof());
     70         assert(!is.fail());
     71         assert(std::wstring(s, 5) == L" 1234");
     72         assert(is.gcount() == 5);
     73         is.readsome(s, 5);
     74         assert(!is.eof());
     75         assert(!is.fail());
     76         assert(std::wstring(s, 5) == L"56789");
     77         assert(is.gcount() == 5);
     78         is.readsome(s, 5);
     79         assert(!is.eof());
     80         assert(!is.fail());
     81         assert(is.gcount() == 1);
     82         assert(std::wstring(s, 1) == L"0");
     83         assert(is.readsome(s, 5) == 0);
     84     }
     85 }
     86