fork download 
  1. #include <iostream>
  2. #include <algorithm>
  3. #include <array>
  4. #include <streambuf>
  5. #include <cassert>
  6.  
  7. namespace GrosserWerner {
  8.   template< unsigned N, unsigned Reserve = 0 >
  9.   class BufferN : public std::streambuf
  10.   {
  11.   public:
  12.     BufferN( std::streambuf* src )
  13.       : src_( src )
  14.       , p0_( 0 )
  15.     {
  16.       setg( buf_, buf_, buf_ );
  17.     }
  18.   protected:
  19.     virtual int_type underflow() override
  20.     {
  21.       assert( gptr() != 0 ); // garantiert der Konstruktor
  22.       assert( gptr() == egptr() ); // ...sollte der Aufrufer garantieren
  23.       const int_type m = src_->sbumpc();
  24.       if( traits_type::eq_int_type( m, traits_type::eof() ) )
  25.         return traits_type::eof();
  26.       if( egptr() == end() )
  27.         {
  28.           traits_type::move( buf_, buf_+(Reserve+1), N-1 );
  29.           setg( buf_, buf_+(N-1), buf_+N );
  30.           p0_ += Reserve+1;
  31.         }
  32.       else
  33.         {
  34.           setg( buf_, egptr(), egptr()+1 );
  35.         }
  36.       *gptr() = traits_type::to_char_type( m );
  37.       return m;
  38.     }
  39.  
  40.     virtual pos_type seekoff( off_type off, std::ios_base::seekdir way, std::ios_base::openmode which = std::ios_base::in | std::ios_base::out) override
  41.     {
  42.       if( which != std::ios_base::in ) // nur input-Zeiger setzen erlaubt
  43.         return pos_type( off_type(-1) );
  44.       off_type local_off; // zeigt in den lokalen 'buf_'
  45.       switch( way )
  46.         {
  47.         case std::ios_base::beg:
  48.           local_off = off_type( off - p0_ );
  49.           break;
  50.  
  51.         case std::ios_base::cur:
  52.           local_off = off + (gptr() - eback());
  53.           break;
  54.  
  55.         case std::ios_base::end: // not implemented
  56.         default:
  57.           return pos_type( off_type(-1) );
  58.         }
  59.       if( local_off < 0 || local_off > off_type(egptr() - eback()) )
  60.         return pos_type( off_type(-1) ); // Fehler: local_off zeigt außerhalb der pending sequence
  61.       setg( buf_, buf_+local_off, egptr() );
  62.       return p0_ + local_off;
  63.     }
  64.     virtual pos_type seekpos( pos_type sp, std::ios_base::openmode which = std::ios_base::in | std::ios_base::out ) override
  65.     {
  66.       return seekoff( off_type(sp - (p0_ + off_type(gptr() - eback()))), std::ios_base::cur, which );
  67.     }
  68.  
  69.   private:
  70.     const char_type* end() const { return buf_ + sizeof(buf_)/sizeof(*buf_); }
  71.     std::streambuf* src_;
  72.     char_type buf_[N+Reserve];
  73.     pos_type p0_;
  74.   };
  75.  
  76.   void parse1(std::istream& in, std::ostream& out)
  77.   {
  78.     out << "Format 1\n";
  79.     std::istreambuf_iterator<char> i(in), j;
  80.     std::copy(i, j, std::ostreambuf_iterator<char>(out));
  81.   }
  82.  
  83.   void parse2(std::istream& in, std::ostream& out)
  84.   {
  85.     out << "Format 2\n";
  86.     std::istreambuf_iterator<char> i(in), j;
  87.     std::copy(i, j, std::ostreambuf_iterator<char>(out));
  88.   }
  89.  
  90.   void parse(std::istream& in, std::ostream& out)
  91.   {
  92.     BufferN< 64, 1 > sb( in.rdbuf() );
  93.     //           ^- don't override the first character
  94.     in.rdbuf( &sb );
  95.     std::istreambuf_iterator< char > it( in );
  96.     int magic = 17;
  97.     for (int i = 0; i < 64; ++i)
  98.       magic = 13*magic + *it++;
  99.     in.seekg( 0, std::ios_base::beg );
  100.     if ( magic%2 )
  101.       parse1( in, out );
  102.     else
  103.       parse2( in, out );
  104.   }
  105. }
  106.  
  107. namespace werni {
  108.   void parse1(std::istreambuf_iterator<char> it, std::istreambuf_iterator<char> end,
  109.               std::ostream& out, std::array<char, 64> const& arr)
  110.   {
  111.     out << "Format 1\n";
  112.     std::ostreambuf_iterator<char> o(out);
  113.     std::copy(arr.begin(), arr.end(), o);
  114.     std::copy(++it, end, o);
  115.   }
  116.  
  117.   void parse2(std::istreambuf_iterator<char> it, std::istreambuf_iterator<char> end,
  118.               std::ostream& out, std::array<char, 64> const& arr)
  119.   {
  120.     out << "Format 2\n";
  121.     std::ostreambuf_iterator<char> o(out);
  122.     std::copy(arr.begin(), arr.end(), o);
  123.     std::copy(++it, end, o);
  124.   }
  125.  
  126.   void parse(std::istream& in, std::ostream& out)
  127.   {
  128.     std::istreambuf_iterator<char> it(in), end;
  129.     std::array<char, 64> save;
  130.     std::copy_n(it, 64, save.begin());
  131.     int magic = 17;
  132.     for (int i=0; i<64; ++i)
  133.       magic = 13*magic + save[i];
  134.     if (magic%2)
  135.       parse1(it, end, out, save);
  136.     else
  137.       parse2(in, end, out, save);
  138.   }
  139. }
  140.  
  141. int main(int argc, char *argv[])
  142. {
  143.   std::ios_base::sync_with_stdio(false);
  144.   if (argc != 2)
  145.     std::cout << "usage: " << argv[0] << " [werni|Werner]";
  146.   else if (std::string("werni") == argv[1])
  147.     werni::parse(std::cin, std::cout);
  148.   else
  149.     GrosserWerner::parse(std::cin, std::cout);
  150. }
Success #stdin #stdout 0s 3040KB
comments (?)
stdin 
Standard input is empty
stdout 
usage: ./prog [werni|Werner]
https://ideone.com/Tl3y8K
language:
C++14 (gcc 8.3)
created:
13 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!