libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/readsome.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 // <istream>
  10
  11 // streamsize readsome(char_type* s, streamsize n);
  12
  13 #include <istream>
  14 #include <cassert>
  15
  16 #include "test_macros.h"
  17
  18 template <class CharT>
  19 struct testbuf
  20     : public std::basic_streambuf<CharT>
  21 {
  22     typedef std::basic_string<CharT> string_type;
  23     typedef std::basic_streambuf<CharT> base;
  24 private:
  25     string_type str_;
  26 public:
  27
  28     testbuf() {}
  29     testbuf(const string_type& str)
  30         : str_(str)
  31     {
  32         base::setg(const_cast<CharT*>(str_.data()),
  33                    const_cast<CharT*>(str_.data()),
  34                    const_cast<CharT*>(str_.data()) + str_.size());
  35     }
  36
  37     CharT* eback() const {return base::eback();}
  38     CharT* gptr() const {return base::gptr();}
  39     CharT* egptr() const {return base::egptr();}
  40 };
  41
  42 int main(int, char**)
  43 {
  44     {
  45         testbuf<char> sb(" 1234567890");
  46         std::istream is(&sb);
  47         char s[5];
  48         assert(is.readsome(s, 5) == 5);
  49         assert(!is.eof());
  50         assert(!is.fail());
  51         assert(std::string(s, 5) == " 1234");
  52         assert(is.gcount() == 5);
  53         is.readsome(s, 5);
  54         assert(!is.eof());
  55         assert(!is.fail());
  56         assert(std::string(s, 5) == "56789");
  57         assert(is.gcount() == 5);
  58         is.readsome(s, 5);
  59         assert(!is.eof());
  60         assert(!is.fail());
  61         assert(is.gcount() == 1);
  62         assert(std::string(s, 1) == "0");
  63         assert(is.readsome(s, 5) == 0);
  64     }
  65 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  66     {
  67         testbuf<wchar_t> sb(L" 1234567890");
  68         std::wistream is(&sb);
  69         wchar_t s[5];
  70         assert(is.readsome(s, 5) == 5);
  71         assert(!is.eof());
  72         assert(!is.fail());
  73         assert(std::wstring(s, 5) == L" 1234");
  74         assert(is.gcount() == 5);
  75         is.readsome(s, 5);
  76         assert(!is.eof());
  77         assert(!is.fail());
  78         assert(std::wstring(s, 5) == L"56789");
  79         assert(is.gcount() == 5);
  80         is.readsome(s, 5);
  81         assert(!is.eof());
  82         assert(!is.fail());
  83         assert(is.gcount() == 1);
  84         assert(std::wstring(s, 1) == L"0");
  85         assert(is.readsome(s, 5) == 0);
  86     }
  87 #endif
  88
  89   return 0;
  90 }