streambuf.h

早期freebsd实现

// This may look like C code, but it is really -*- C++ -*-
/* 
Copyright (C) 1988, 1992 Free Software Foundation
    written by Doug Lea ([e-mail])

This file is part of the GNU C++ Library.  This library is free
software; you can redistribute it and/or modify it under the terms of
the GNU Library General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your
option) any later version.  This library is distributed in the hope
that it will be useful, but WITHOUT ANY WARRANTY; without even the
implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.  See the GNU Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free Software
Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifndef _streambuf_h
#ifdef __GNUG__
#pragma interface
#endif
#define _streambuf_h 1

/* streambufs. 
   basic streambufs and filebufs are as in Stroustrup, ch 8,
   but the base class contains virtual extensions that allow
   most capabilities of libg++ Files to be used as streambufs
   via `Filebufs'.
*/

#include <stdio.h>
#include <builtin.h>
#include <Fmodes.h>

// Flag used to distinguish old streams from new iostreams.
#define _OLD_STREAMS

// see below for NO_LINE_BUFFER_STREAMBUFS

#ifndef BUFSIZE
#ifdef BUFSIZ
#define BUFSIZE BUFSIZ
#else
#define BUFSIZE 1024
#endif
#endif

enum open_mode // filebuf open modes
{ 
  input=0, 
  output=1, 
  append=2 
}; 

class streambuf
{
public:
  char*       base;          // start of buffer
  char*       pptr;          // put-pointer (and gptr fence)
  char*       gptr;          // get-pointer
  char*       eptr;          // last valid addr in buffer

  char        alloc;         // true if we own freestore alloced buffer

              streambuf();
              streambuf(char* buf, int buflen);
 
  virtual    ~streambuf();

  int         doallocate();
  int         allocate();


  int         must_overflow(int ch); // true if should call overflow

  virtual int overflow(int c = EOF); // flush -- return EOF if fail
  virtual int underflow();           // fill -- return EOF if fail

  int         sgetc();          // get one char (as int) or EOF
  int         snextc();         // get and advance
  void        stossc();         // advance only

  int         sputbackc(char);   // unget

  int         sputc(int c = EOF); // write one char

  virtual streambuf*  setbuf(char* buf, int buflen, int preloaded_count = 0);
                                // (not virtual in AT&T)

// the following aren't in AT&T version:

  int         sputs(const char* s);           // write null-terminated str
  int         sputsn(const char* s, int len); // write len bytes

  virtual const char* name();


  virtual streambuf*  open(const char* name, open_mode m);
  virtual streambuf*  open(const char* filename, io_mode m, access_mode a);
  virtual streambuf*  open(const char* filename, const char* m);
  virtual streambuf*  open(int  filedesc, io_mode m);
  virtual streambuf*  open(FILE* fileptr);

  virtual int         is_open();
  virtual int         close();

  virtual void        error();
};


#if defined(__OPTIMIZE__) || defined(USE_LIBGXX_INLINES)


inline int streambuf::must_overflow(int ch)
{
#ifndef NO_LINE_BUFFER_STREAMBUF
  return pptr >= eptr || ch == '\n';
#else
  return pptr >= eptr;
#endif
}


inline int streambuf::allocate()
{
  return (base == 0)? doallocate() : 0; 
}

inline int streambuf::sgetc()
{
  return (gptr >= pptr)? underflow() : int((unsigned char)(*gptr));
}


inline int streambuf::snextc()
{
  ++gptr;
  return (gptr >= pptr)? underflow() : int((unsigned char)(*gptr));
}


inline void streambuf::stossc()
{
  if (gptr >= pptr) underflow(); else gptr++;
}


inline int streambuf::sputbackc(char ch)
{
  return (gptr > base)? int((unsigned char)(*--gptr = ch)) : EOF;
}

inline int streambuf::sputc(int ch)
{
  return must_overflow(ch)? overflow(ch) : 
                            int((unsigned char)(*pptr++ = char(ch)));
}

#endif

#endif