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// file : libbutl/bufstreambuf.hxx -*- C++ -*-
// license : MIT; see accompanying LICENSE file
#pragma once
#include <cstdint> // uint64_t
#include <streambuf>
#include <libbutl/export.hxx>
namespace butl
{
// A buffered streambuf interface that exposes its buffer for direct scan
// and provides a notion of logical position. See fdstreambuf for background
// and motivation.
//
class LIBBUTL_SYMEXPORT bufstreambuf: public std::basic_streambuf<char>
{
public:
using base = std::basic_streambuf<char>;
using int_type = base::int_type;
using traits_type = base::traits_type;
using pos_type = base::pos_type; // std::streampos
using off_type = base::off_type; // std::streamoff
public:
explicit
bufstreambuf (std::uint64_t pos = 0): off_ (pos) {}
virtual
~bufstreambuf ();
// basic_streambuf input interface.
//
public:
// Direct access to the get area. Use with caution.
//
using base::gptr;
using base::egptr;
using base::gbump;
// Return the (logical) position of the next byte to be read.
//
// Note that on Windows when reading in the text mode the logical position
// may differ from the physical file descriptor position due to the CRLF
// character sequence translation. See the fdstreambuf::seekoff()
// implementation for more background on this issue.
//
std::uint64_t
tellg () const {return off_ - (egptr () - gptr ());}
// basic_streambuf output interface.
//
public:
// Return the (logical) position of the next byte to be written.
//
std::uint64_t
tellp () const {return off_ + (pptr () - pbase ());}
protected:
std::uint64_t off_;
};
}
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