cfile_device_base.hpp

#ifndef CFILE_DEVICE_BASE_HPP_INCLUDED
#define CFILE_DEVICE_BASE_HPP_INCLUDED

// cfile_device_base.hpp
// 
// Copyright (c) 2009 - Michele De Stefano (micdestefano@users.sourceforge.net)
// 
// Distributed under the MIT License (See accompanying file LICENSE)

#include <mds_utils/file_utils/detail/cfile_stream_fwd.hpp>
#include <iosfwd>                          // streamsize
#include <boost/iostreams/categories.hpp>  // source_tag
#include <boost/iostreams/traits.hpp>
#include <boost/iostreams/positioning.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/mpl/if.hpp>
#include <boost/mpl/not.hpp>
#include <cstdio>


namespace mds_utils { namespace file_utils {
        
    // Contains implementation details (not to be used by the user)
    namespace detail {

// Base class for all FILE* devices
template<class Derived>
class cFile_Device_base {

protected:
    
    FILE        *file_ptr;  // The FILE pointer
    
public:
    
    typedef char                char_type;
    struct category : virtual boost::iostreams::device_tag,
        virtual boost::mpl::if_<
            boost::is_same<Derived,cFile_Sink>,
            boost::iostreams::output_seekable,
            typename boost::mpl::if_<
                boost::is_same<Derived,cFile_Source>,
                boost::iostreams::input_seekable,
                boost::iostreams::seekable
            >::type
        >::type,
        virtual boost::mpl::if_<boost::mpl::not_<
            boost::is_same<Derived,cFile_Source> >,
            boost::iostreams::flushable_tag,
            boost::iostreams::any_tag
        >::type {};
    
    cFile_Device_base() {}
    cFile_Device_base(FILE *ptr) : file_ptr(ptr) {}
    
    void set_FILEp(FILE *ptr) { file_ptr = ptr; }
    
    boost::iostreams::stream_offset
        seek(boost::iostreams::stream_offset off,std::ios_base::seekdir way) {
        
        using namespace boost::iostreams;
        using namespace std;
        
        stream_offset   next;
        int             whence;
        switch (way) {
        case ios_base::beg:
            whence = SEEK_SET;
            break;
        case ios_base::cur:
            whence = SEEK_CUR;
            break;
        case ios_base::end:
            whence = SEEK_END;
            break;
        default:
            throw ios_base::failure("Bad seek direction (cFile_Device_base::seek)");
        }
        
#ifdef HAVE_FSEEKO
        fseeko(file_ptr,off,whence);
        next = ftello(file_ptr);
#else
        fseek(file_ptr,off,whence);
        next = ftell(file_ptr);
#endif
        
        return next;
    }
};

    } // namespace detail
    
#define DEF_READ \
std::streamsize read(char_type *s,std::streamsize n) {  \
    if (feof(file_ptr)) return -1;  \
    return fread(reinterpret_cast<void*>(s),sizeof(char),n,file_ptr);   \
}

#define DEF_WRITE \
std::streamsize write(const char_type *s,std::streamsize n) {   \
    return fwrite(reinterpret_cast<const void*>(s),sizeof(char),n,file_ptr);    \
}

#define DEF_FLUSH \
bool flush() { return (fflush(file_ptr) == 0); }


}}


#endif