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  1. #include <set>
  2. #include <ostream>
  3. #include <streambuf>
  4.  
  5. template< typename CharT,
  6.           typename Traits = std::char_traits<CharT> >
  7. struct StreamSplitBuffer : std::basic_streambuf<CharT, Traits>
  8. {
  9.     typedef std::basic_streambuf<CharT, Traits> streambuf_type;
  10.     typedef std::basic_ostream<CharT, Traits> ostream_type;
  11.  
  12.     ostream_type& mOriginal;
  13.  
  14.     streambuf_type* const mBase;
  15.     std::set<streambuf_type*> mStreambufs;
  16.  
  17. public:
  18.  
  19.     StreamSplitBuffer( ostream_type& os ):
  20.         mOriginal(os), // no list-initialization syntax for references
  21.         mBase{os.rdbuf()}
  22.     {
  23.         add(mBase);
  24.         mOriginal.rdbuf( this );
  25.     }
  26.  
  27.     ~StreamSplitBuffer()
  28.     {
  29.         mOriginal.rdbuf( mBase );
  30.     }
  31.  
  32.     typedef CharT char_type;
  33.     typedef Traits traits_type;
  34.  
  35.     typedef typename std::set<streambuf_type*>::iterator iterator;
  36.     typedef typename std::set<streambuf_type*>::const_iterator const_iterator;
  37.  
  38.     iterator begin() { return mStreambufs.begin(); }
  39.     iterator end() { return mStreambufs.end(); }
  40.     const_iterator begin() const { return mStreambufs.cbegin(); }
  41.     const_iterator end() const { return mStreambufs.cend(); }
  42.  
  43.     std::pair<iterator, bool> add( streambuf_type* ptr ) { return mStreambufs.insert(ptr); }
  44.     std::pair<iterator, bool> add( ostream_type& ptr ) { return add(ptr.rdbuf()); }
  45.  
  46.     void erase( iterator i ) {  mStreambufs.erase(i); }
  47.  
  48. protected:
  49.  
  50.     virtual typename traits_type::int_type overflow( typename traits_type::int_type c = traits_type::eof() ) override
  51.     {
  52.         typename traits_type::int_type rval = traits_type::not_eof(c);
  53.  
  54.         if( !traits_type::eq_int_type( rval, c ) ) /// EOF - no characters to be written. Return success.
  55.             return rval;
  56.  
  57.         for( auto ptr : *this )
  58.             if( traits_type::eq_int_type( ptr->sputc( traits_type::to_char_type(c) ), traits_type::eof() ) )
  59.                 rval = traits_type::eof(); // if one streambuf returns a value indicating failure, all other streambufs are done and EOF is returned.
  60.  
  61.         return rval;
  62.     }
  63. };
  64.  
  65. #include <iostream>
  66. #include <sstream>
  67.  
  68. int main()
  69. {
  70.     StreamSplitBuffer<char> splitter(std::cout);
  71.  
  72.     std::ostringstream stream;
  73.     splitter.add(stream);
  74.  
  75.     std::cout << "Hallo Welt!\nWie gehts?";
  76.  
  77.     std::cout << '\n' << stream.str();
  78. }
Success #stdin #stdout 0s 2988KB
comments (?)
stdin 
Standard input is empty
stdout 
Hallo Welt!
Wie gehts?
Hallo Welt!
Wie gehts?
https://ideone.com/tqWJpV
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
secret

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