Home | History | Annotate | Download | only in istream_sentry 
      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 // template <class charT, class traits = char_traits<charT> >
     13 // class basic_istream::sentry;
     14 
     15 // explicit sentry(basic_istream<charT,traits>& is, bool noskipws = false);
     16 
     17 #include <istream>
     18 #include <cassert>
     19 
     20 int sync_called = 0;
     21 
     22 template <class CharT>
     23 struct testbuf
     24     : public std::basic_streambuf<CharT>
     25 {
     26     typedef std::basic_string<CharT> string_type;
     27     typedef std::basic_streambuf<CharT> base;
     28 private:
     29     string_type str_;
     30 public:
     31 
     32     testbuf() {}
     33     testbuf(const string_type& str)
     34         : str_(str)
     35     {
     36         base::setg(const_cast<CharT*>(str_.data()),
     37                    const_cast<CharT*>(str_.data()),
     38                    const_cast<CharT*>(str_.data()) + str_.size());
     39     }
     40 
     41     CharT* eback() const {return base::eback();}
     42     CharT* gptr() const {return base::gptr();}
     43     CharT* egptr() const {return base::egptr();}
     44 protected:
     45 
     46     int virtual sync()
     47     {
     48         ++sync_called;
     49         return 1;
     50     }
     51 };
     52 
     53 int main()
     54 {
     55     {
     56         std::istream is((testbuf<char>*)0);
     57         std::istream::sentry sen(is, true);
     58         assert(!(bool)sen);
     59         assert(!is.good());
     60         assert(is.gcount() == 0);
     61         assert(sync_called == 0);
     62     }
     63     {
     64         std::wistream is((testbuf<wchar_t>*)0);
     65         std::wistream::sentry sen(is, true);
     66         assert(!(bool)sen);
     67         assert(!is.good());
     68         assert(is.gcount() == 0);
     69         assert(sync_called == 0);
     70     }
     71     {
     72         testbuf<char> sb("   123");
     73         std::istream is(&sb);
     74         std::istream::sentry sen(is, true);
     75         assert((bool)sen);
     76         assert(is.good());
     77         assert(is.gcount() == 0);
     78         assert(sync_called == 0);
     79         assert(sb.gptr() == sb.eback());
     80     }
     81     {
     82         testbuf<wchar_t> sb(L"   123");
     83         std::wistream is(&sb);
     84         std::wistream::sentry sen(is, true);
     85         assert((bool)sen);
     86         assert(is.good());
     87         assert(is.gcount() == 0);
     88         assert(sync_called == 0);
     89         assert(sb.gptr() == sb.eback());
     90     }
     91     {
     92         testbuf<char> sb("   123");
     93         std::istream is(&sb);
     94         std::istream::sentry sen(is);
     95         assert((bool)sen);
     96         assert(is.good());
     97         assert(sync_called == 0);
     98         assert(sb.gptr() == sb.eback() + 3);
     99     }
    100     {
    101         testbuf<wchar_t> sb(L"   123");
    102         std::wistream is(&sb);
    103         std::wistream::sentry sen(is);
    104         assert((bool)sen);
    105         assert(is.good());
    106         assert(sync_called == 0);
    107         assert(sb.gptr() == sb.eback() + 3);
    108     }
    109     {
    110         testbuf<char> sb("      ");
    111         std::istream is(&sb);
    112         std::istream::sentry sen(is);
    113         assert(!(bool)sen);
    114         assert(is.fail());
    115         assert(is.eof());
    116         assert(sync_called == 0);
    117         assert(sb.gptr() == sb.eback() + 6);
    118     }
    119     {
    120         testbuf<char> sb("      ");
    121         std::istream is(&sb);
    122         std::istream::sentry sen(is, true);
    123         assert((bool)sen);
    124         assert(is.good());
    125         assert(sync_called == 0);
    126         assert(sb.gptr() == sb.eback());
    127     }
    128 }
    129