libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/underflow.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 // REQUIRES: locale.en_US.UTF-8
  10 // FILE_DEPENDENCIES: underflow.dat, underflow_utf8.dat
  11
  12 // <fstream>
  13
  14 // int_type underflow();
  15
  16 // This test is not entirely portable
  17
  18 #include <fstream>
  19 #include <cstddef>
  20 #include <cassert>
  21
  22 #include "test_macros.h"
  23 #include "platform_support.h" // locale name macros
  24
  25 template <class CharT>
  26 struct test_buf
  27     : public std::basic_filebuf<CharT>
  28 {
  29     typedef std::basic_filebuf<CharT> base;
  30     typedef typename base::char_type  char_type;
  31     typedef typename base::int_type   int_type;
  32
  33     char_type* eback() const {return base::eback();}
  34     char_type* gptr()  const {return base::gptr();}
  35     char_type* egptr() const {return base::egptr();}
  36     void gbump(int n) {base::gbump(n);}
  37
  38     virtual int_type underflow() {return base::underflow();}
  39 };
  40
  41 int main(int, char**)
  42 {
  43     {
  44         test_buf<char> f;
  45         assert(f.open("underflow.dat", std::ios_base::in) != 0);
  46         assert(f.is_open());
  47         assert(f.eback() == 0);
  48         assert(f.gptr() == 0);
  49         assert(f.egptr() == 0);
  50         assert(f.underflow() == '1');
  51         assert(f.eback() != 0);
  52         assert(f.eback() == f.gptr());
  53         assert(*f.gptr() == '1');
  54         assert(f.egptr() - f.eback() == 9);
  55     }
  56     {
  57         test_buf<char> f;
  58         assert(f.open("underflow.dat", std::ios_base::in) != 0);
  59         assert(f.pubsetbuf(0, 0));
  60         assert(f.is_open());
  61         assert(f.eback() == 0);
  62         assert(f.gptr() == 0);
  63         assert(f.egptr() == 0);
  64         assert(f.underflow() == '1');
  65         assert(f.eback() != 0);
  66         assert(f.eback() == f.gptr());
  67         assert(*f.gptr() == '1');
  68         assert(f.egptr() - f.eback() == 8);
  69         f.gbump(8);
  70         assert(f.sgetc() == '9');
  71         assert(f.eback()[0] == '5');
  72         assert(f.eback()[1] == '6');
  73         assert(f.eback()[2] == '7');
  74         assert(f.eback()[3] == '8');
  75         assert(f.gptr() - f.eback() == 4);
  76         assert(*f.gptr() == '9');
  77         assert(f.egptr() - f.gptr() == 1);
  78     }
  79 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  80     {
  81         test_buf<wchar_t> f;
  82         assert(f.open("underflow.dat", std::ios_base::in) != 0);
  83         assert(f.is_open());
  84         assert(f.eback() == 0);
  85         assert(f.gptr() == 0);
  86         assert(f.egptr() == 0);
  87         assert(f.underflow() == L'1');
  88         assert(f.eback() != 0);
  89         assert(f.eback() == f.gptr());
  90         assert(*f.gptr() == L'1');
  91         assert(f.egptr() - f.eback() == 9);
  92     }
  93     {
  94         test_buf<wchar_t> f;
  95         assert(f.pubsetbuf(0, 0));
  96         assert(f.open("underflow.dat", std::ios_base::in) != 0);
  97         assert(f.is_open());
  98         assert(f.eback() == 0);
  99         assert(f.gptr() == 0);
 100         assert(f.egptr() == 0);
 101         assert(f.underflow() == L'1');
 102         assert(f.eback() != 0);
 103         assert(f.eback() == f.gptr());
 104         assert(*f.gptr() == L'1');
 105         assert(f.egptr() - f.eback() == 8);
 106         f.gbump(8);
 107         assert(f.sgetc() == L'9');
 108         assert(f.eback()[0] == L'5');
 109         assert(f.eback()[1] == L'6');
 110         assert(f.eback()[2] == L'7');
 111         assert(f.eback()[3] == L'8');
 112         assert(f.gptr() - f.eback() == 4);
 113         assert(*f.gptr() == L'9');
 114         assert(f.egptr() - f.gptr() == 1);
 115     }
 116     {
 117         typedef std::char_traits<wchar_t> Traits;
 118         test_buf<wchar_t> f;
 119         f.pubimbue(std::locale(LOCALE_en_US_UTF_8));
 120         assert(f.open("underflow_utf8.dat", std::ios_base::in) != 0);
 121         assert(f.is_open());
 122         assert(f.sbumpc() == 0x4E51);
 123         assert(f.sbumpc() == 0x4E52);
 124         assert(f.sbumpc() == 0x4E53);
 125         assert(f.sbumpc() == static_cast<Traits::int_type>(-1));
 126     }
 127 #endif // TEST_HAS_NO_WIDE_CHARACTERS
 128
 129   return 0;
 130 }