I have a Visual Studio 2008 C++ application where I would like to treat a stream as a set of iterators.
For example, if I were to receive an array of WIN32_FIND_DATA structures over the stream, I would like to be able to do something like this:
IStreamBuf< WIN32_FIND_DATA > sb( stream );
std::vector< WIN32_FIND_DATA > buffer;
std::copy( std::istreambuf_iterator< WIN32_FIND_DATA >( &sb ),
std::istreambuf_iterator< WIN32_FIND_DATA >(),
std::back_inserter( buffer ) );
To accomplish this, I've defined a class derived from std::basic_streambuf<>
:
template< typename T >
class IStreamBuf : public std::basic_streambuf< byte >
{
public:
IStreamBuf( IStream* stream ) : stream_( stream )
{
};
protected:
virtual traits_type::int_type underflow()
{
DWORD bytes_read = 0;
HRESULT hr = stream_->Read( &buffer_, sizeof( T ), &bytes_read );
if( FAILED( hr ) )
return traits_type::eof();
traits_type::char_type* begin =
reinterpret_cast< traits_type::char_type* >( &buffer_ );
setg( begin, begin, begin + bytes_read );
return traits_type::to_int_type( *gptr() );
};
private:
// buffer to hold current item of type T
T buffer_;
// stream used to receive data
IStrea开发者_如何学Pythonm* stream_;
}; // class IStreamBuf
What I can't figure out is how to gracefully go from an array of byte
s to an array of WIN32_FIND_DATA
s. Because std::basic_streambuf<>
requires a std::char_traits<>
template parameter, I'm under the impression that it can only use built-in types like char
or byte
, not a structure like WIN32_FIND_DATA
. Correct?
Any suggestions on how to make this work?
Thanks, PaulH
An istreambuf_iterator
works at the buffer level, where it's just a stream of bytes. If you want to deal with structures, you probably want to use an istream_iterator
instead, and create an operator>>
to read the WIN32_FIND_DATA
structures. You might also consider creating/using a proxy for the WIN32_FIND_DATA
.
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