Convertir a std::ifstream& en un autre std::istream&

Salut, alors j'ai une classe qui contient un object de type std::istream&, cette classe décompresse simplement des données en mémoire à l'aide d'un stringstream.

Code:

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 void decompress_stdin(void)
    {
      std::stringstream output;
      output<<buffer;
      int i, out_len;
      char *buffer, *output_buffer;
      i = output.str().size();
 
      /* allocate input and output buffers */
      buffer = new char[MAX_COMPRESSED_LENGTH];
      output_buffer = new char[MAX_DECOMPRESSED_LENGTH];
 
      /* read input from stdin */
      if (i == MAX_DECOMPRESSED_LENGTH)
      {
          std::cerr<<"ERROR: Input is too long!"<<std::endl;
          return;
      }
      buffer = output.str().c_str();
      output.str("");
      /* make decompression */
      out_len = utf16_decompress((u8 *)buffer, i, (u16 *)output_buffer);
      delete[] buffer;
      output.str(std::string(output_buffer));
      buffer = output;
      delete[] output_buffer;
    }

Jusque là ça compile, j'arrive bien à extraire les données du stream, les mettre en mémoire, décompresser et ensuite les remettre dans le stream.

Ce que je voudrais faire c'est ensuite, mettre les données décompressée du stream de cette classe dans un autre type de flux. (par exemple un ifstream)

J'ai donc redéfini l'opérateur >>

Code:

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std::istream& operator>>(std::istream& in) {
        decompress_stdin();
        in = buffer;
        return in;
    }

Ce code-ci ne compile pas et celui là :

Code:

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std::istream& operator>>(std::istream& in) {
        decompress_stdin();
        std::stringstream input;
        input<<buffer;
        in = input;
        return in;
    }

Ne compile pas non plus.

Voici l'erreur que gcc me renvoie :

Code:

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||=== Build: Debug in ODFAEG (compiler: GNU GCC Compiler) ===|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/actionMap.h|85|warning: "/*" within comment [-Wcomment]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/application.h|176|warning: "/*" within comment [-Wcomment]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../../../include/odfaeg/Core/archive.h||In member function ‘void odfaeg::OTextArchive::compress_stdin()’:|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../../../include/odfaeg/Core/archive.h|68|warning: invalid conversion from ‘const char*’ to ‘char*’ [-fpermissive]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../../../include/odfaeg/Core/archive.h|81|warning: invalid user-defined conversion from ‘std::stringstream {aka std::basic_stringstream<char>}’ to ‘char*’ [-fpermissive]|
/usr/include/c++/4.8/bits/basic_ios.h|115|note: candidate is: std::basic_ios<_CharT, _Traits>::operator void*() const [with _CharT = char; _Traits = std::char_traits<char>] <near match>|
/usr/include/c++/4.8/bits/basic_ios.h|115|note:   no known conversion for implicit ‘this’ parameter from ‘void*’ to ‘char*’|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../../../include/odfaeg/Core/archive.h|55|warning: variable ‘out_len’ set but not used [-Wunused-but-set-variable]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../../../include/odfaeg/Core/archive.h||In member function ‘void odfaeg::ITextArchive::decompress_stdin()’:|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../../../include/odfaeg/Core/archive.h|333|warning: invalid conversion from ‘const char*’ to ‘char*’ [-fpermissive]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../../../include/odfaeg/Core/archive.h|339|warning: invalid user-defined conversion from ‘std::stringstream {aka std::basic_stringstream<char>}’ to ‘char*’ [-fpermissive]|
/usr/include/c++/4.8/bits/basic_ios.h|115|note: candidate is: std::basic_ios<_CharT, _Traits>::operator void*() const [with _CharT = char; _Traits = std::char_traits<char>] <near match>|
/usr/include/c++/4.8/bits/basic_ios.h|115|note:   no known conversion for implicit ‘this’ parameter from ‘void*’ to ‘char*’|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../../../include/odfaeg/Core/archive.h|319|warning: variable ‘out_len’ set but not used [-Wunused-but-set-variable]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../../../include/odfaeg/Core/archive.h||In member function ‘std::istream& odfaeg::ITextArchive::operator>>(std::istream&)’:|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../../../include/odfaeg/Core/archive.h|508|error: use of deleted function ‘std::basic_istream<char>& std::basic_istream<char>::operator=(const std::basic_istream<char>&)’|
/usr/include/c++/4.8/istream|58|note: ‘std::basic_istream<char>& std::basic_istream<char>::operator=(const std::basic_istream<char>&)’ is implicitly deleted because the default definition would be ill-formed:|
/usr/include/c++/4.8/istream|58|error: use of deleted function ‘std::basic_ios<char>& std::basic_ios<char>::operator=(const std::basic_ios<char>&)’|
/usr/include/c++/4.8/bits/basic_ios.h|66|note: ‘std::basic_ios<char>& std::basic_ios<char>::operator=(const std::basic_ios<char>&)’ is implicitly deleted because the default definition would be ill-formed:|
/usr/include/c++/4.8/bits/ios_base.h|789|error: ‘std::ios_base& std::ios_base::operator=(const std::ios_base&)’ is private|
/usr/include/c++/4.8/bits/basic_ios.h|66|error: within this context|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/image.hpp|40|warning: declaration ‘class sf::InputStream’ does not declare anything [enabled by default]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/listener.h||In member function ‘void odfaeg::Listener::connect(std::string, odfaeg::Command)’:|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/listener.h|23|warning: left operand of comma operator has no effect [-Wunused-value]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/listener.h|23|warning: right operand of comma operator has no effect [-Wunused-value]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../Graphics/2D/../../Math/computer.h|269|warning: comparison between signed and unsigned integer expressions [-Wsign-compare]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../Graphics/2D/../../Math/computer.h|286|warning: comparison between signed and unsigned integer expressions [-Wsign-compare]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../Graphics/2D/../../Math/computer.h|288|warning: comparison between signed and unsigned integer expressions [-Wsign-compare]|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../Graphics/2D/entity.h||In member function ‘bool odfaeg::g2d::Entity::removeAttribute(std::string)’:|
/home/laurent/Développement/Projets-c++/ODFAEG/src/odfaeg/Core/../../../include/odfaeg/Core/../Graphics/../Graphics/2D/entity.h|103|warning: no return statement in function returning non-void [-Wreturn-type]|
||=== Build failed: 4 error(s), 15 warning(s) (0 minute(s), 4 second(s)) ===|

Pourquoi est ce que ma fonction decompress compile bien et que en faisant la même chose dans ma fonction operator>> ça ne compile plus ???

Ai je chopé une mauvaise version de la STL ???

Ce code devrait compilé sans problème non ?

Argh non en fait me suis trompé de variable c'est this->buffer du coup ma fonction de décompressage ne compile pas non plus :

Code:

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 void compress_stdin(void)
    {
      std::stringstream output;
      output<<buffer;
      int i, out_len;
      char *buffer, *output_buffer;
      i = output.str().size();
      /* allocate input and output buffers */
      buffer = new char[MAX_DECOMPRESSED_LENGTH];
      output_buffer = new char [MAX_COMPRESSED_LENGTH];
 
      /* read input from stdin */
      if (i == MAX_DECOMPRESSED_LENGTH)
      {
        std::cerr<<"ERROR: Input is too long!"<<std::endl;
        return;
      }
      buffer = output.str().c_str();
      output.str("");
 
      /* each utf16 character is 2 bytes long so the input number of bytes must be odd */
      if (i % 2 != 0)
        fprintf(stderr, "WARNING: odd number of input bytes!\n");
 
      /* compress */
      out_len = utf16_compress((u16 *)buffer, i / 2, (u8 *)output_buffer);
 
      delete[] buffer;
      output.str(std::string(output_buffer));
      delete[] output_buffer;
      this->buffer = output;
    }

Bah je vois pas pourquoi ça me met une erreur.

J'ai trouvé!

Code:

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 std::istream& operator>>(std::istream& in) {
        decompress_stdin();
        std::streambuf * pbuf = buffer.rdbuf();
        std::streamsize size = pbuf->pubseekoff(0,buffer.end);
        char contents = new char [size];
        pbuf->sgetn (contents,size);
        in.rdbuf()->pubsetbuf(contents, size);
        return in;
    }