streambuf.h

早期freebsd实现

#else
    friend int __underflow(streambuf*);
#endif
    struct streammarker *_next;  // Only if saving()
    streambuf *_sbuf; // Only valid if saving().
    streampos _spos; // -2: means that _pos is valid.
    void set_streampos(streampos sp) { _spos = sp; }
    void set_offset(int offset) { _pos = offset; _spos = (streampos)(-2); }
    // If _pos >= 0, it points to _buf->Gbase()+_pos.
    // if _pos < 0, it points to _buf->eBptr()+_pos.
    int _pos;
  public:
    streammarker(streambuf *sb);
    ~streammarker();
    int saving() { return  _spos == -2; }
    int delta(streammarker&);
    int delta();
};

struct __streambuf {
    // NOTE: If this is changed, also change __FILE in stdio/stdio.h!
    int _flags;		/* High-order word is _IO_MAGIC; rest is flags. */
    char* _gptr;	/* Current get pointer */
    char* _egptr;	/* End of get area. */
    char* _eback;	/* Start of putback+get area. */
    char* _pbase;	/* Start of put area. */
    char* _pptr;	/* Current put pointer. */
    char* _epptr;	/* End of put area. */
    char* _base;	/* Start of reserve area. */
    char* _ebuf;	/* End of reserve area. */
    struct streambuf *_chain;

    // The following fields are used to support backing up and undo.
    friend class streammarker;
    char *_other_gbase; // Pointer to start of non-current get area.
    char *_aux_limit;  // Pointer to first valid character of backup area,
    char *_other_egptr; // Pointer to end of non-current get area.
    streammarker *_markers;

#define __HAVE_COLUMN /* temporary */
    // 1+column number of pbase(); 0 is unknown.
    unsigned short _cur_column;
    char _unused;
    char _shortbuf[1];
};

extern unsigned __adjust_column(unsigned start, const char *line, int count);

struct streambuf : private __streambuf {
    friend class ios;
    friend class istream;
    friend class ostream;
    friend class streammarker;
#ifdef _G_FRIEND_BUG
    friend int __UNDERFLOW(streambuf*);
#else
    friend int __underflow(streambuf*);
#endif
  protected:
    static streambuf* _list_all; /* List of open streambufs. */
    streambuf*& xchain() { return _chain; }
    void _un_link();
    void _link_in();
    char* gptr() const { return _gptr; }
    char* pptr() const { return _pptr; }
    char* egptr() const { return _egptr; }
    char* epptr() const { return _epptr; }
    char* pbase() const { return _pbase; }
    char* eback() const { return _eback; }
    char* base() const { return _base; }
    char* ebuf() const { return _ebuf; }
    int blen() const { return _ebuf - _base; }
    void xput_char(char c) { *_pptr++ = c; }
    int xflags() { return _flags; }
    int xflags(int f) { int fl = _flags; _flags = f; return fl; }
    void xsetflags(int f) { _flags |= f; }
    void xsetflags(int f, int mask) { _flags = (_flags & ~mask) | (f & mask); }
    void gbump(int n) { _gptr += n; }
    void pbump(int n) { _pptr += n; }
    void setb(char* b, char* eb, int a=0);
    void setp(char* p, char* ep) { _pbase=_pptr=p; _epptr=ep; }
    void setg(char* eb, char* g, char *eg) { _eback=eb; _gptr=g; _egptr=eg; }
    char *shortbuf() { return _shortbuf; }

    int in_backup() { return _flags & _S_IN_BACKUP; }
    // The start of the main get area:  FIXME:  wrong for write-mode filebuf?
    char *Gbase() { return in_backup() ? _other_gbase : _eback; }
    // The end of the main get area:
    char *eGptr() { return in_backup() ? _other_egptr : _egptr; }
    // The start of the backup area:
    char *Bbase() { return in_backup() ? _eback : _other_gbase; }
    char *Bptr() { return _aux_limit; }
    // The end of the backup area:
    char *eBptr() { return in_backup() ? _egptr : _other_egptr; }
    char *Nbase() { return _other_gbase; }
    char *eNptr() { return _other_egptr; }
    int have_backup() { return _other_gbase != NULL; }
    int have_markers() { return _markers != NULL; }
    int _least_marker();
    void switch_to_main_get_area();
    void switch_to_backup_area();
    void free_backup_area();
    void unsave_markers(); // Make all streammarkers !saving().
    int put_mode() { return _flags & _S_CURRENTLY_PUTTING; }
    int switch_to_get_mode();
    
    streambuf(int flags=0);
  public:
    static int flush_all();
    static void flush_all_linebuffered(); // Flush all line buffered files.
    virtual int underflow() = 0; // Leave public for now
    virtual int overflow(int c = EOF) = 0; // Leave public for now
    virtual int doallocate();
    virtual streampos seekoff(streamoff, _seek_dir, int mode=ios::in|ios::out);
    virtual streampos seekpos(streampos pos, int mode = ios::in|ios::out);
    int seekmark(streammarker& mark, int delta = 0);
    int sputbackc(char c);
    int sungetc();
    virtual ~streambuf();
    int unbuffered() { return _flags & _S_UNBUFFERED ? 1 : 0; }
    int linebuffered() { return _flags & _S_LINE_BUF ? 1 : 0; }
    void unbuffered(int i)
	{ if (i) _flags |= _S_UNBUFFERED; else _flags &= ~_S_UNBUFFERED; }
    void linebuffered(int i)
	{ if (i) _flags |= _S_LINE_BUF; else _flags &= ~_S_LINE_BUF; }
    int allocate() { // For AT&T compatibility
	if (base() || unbuffered()) return 0;
	else return doallocate(); }
    // Allocate a buffer if needed; use _shortbuf if appropriate.
    void allocbuf() { if (base() == NULL) doallocbuf(); }
    void doallocbuf();
    virtual int sync();
    virtual int pbackfail(int c);
    virtual streambuf* setbuf(char* p, int len);
    int in_avail() { return _egptr - _gptr; }
    int out_waiting() { return _pptr - _pbase; }
    virtual int xsputn(const char* s, int n);
    int sputn(const char* s, int n) { return xsputn(s, n); }
    int padn(char pad, int n); // Emit 'n' copies of 'pad'.
    virtual int xsgetn(char* s, int n);
    int sgetn(char* s, int n) { return xsgetn(s, n); }
    int ignore(int);
    virtual int get_column();
    virtual int set_column(int);
    long sgetline(char* buf, _G_size_t n, char delim, int putback_delim);
    int sbumpc() {
	if (_gptr >= _egptr && __underflow(this) == EOF) return EOF;
	else return *(unsigned char*)_gptr++; }
    int sgetc() {
	if (_gptr >= _egptr && __underflow(this) == EOF) return EOF;
	else return *(unsigned char*)_gptr; }
    int snextc() {
	if (_gptr >= _egptr && __underflow(this) == EOF) return EOF;
	return _gptr++, sgetc(); }
    int sputc(int c) {
	if (_pptr >= _epptr) return __overflow(this, (unsigned char)c);
	else return *_pptr++ = c, (unsigned char)c; }
    void stossc() { if (_gptr < _egptr) _gptr++; }
    int vscan(char const *fmt0, _G_va_list ap, ios* stream = NULL);
    int scan(char const *fmt0 ...);
    int vform(char const *fmt0, _G_va_list ap);
    int form(char const *fmt0 ...);
#if 0 /* Work in progress */
    int collumn();  // Current collumn number (of put pointer). -1 is unknown.
    void collumn(int c);  // Set collumn number of put pointer to c.
#endif
};

// A backupbuf is a streambuf with full backup and savepoints on reading.
// All standard streambufs in the GNU iostream library are backupbufs.

// A backupbuf may have two get area:
// - The main get area, and (sometimes) the putback area.
// Whichever one of these contains the gptr is the current get area;
// the other one is the non-current get area.

class backupbuf : public streambuf {
    friend class streammarker;
  protected:
    backupbuf(int flags=0) : streambuf(flags|_S_IS_BACKUPBUF) { }
  public:
    virtual int pbackfail(int c);
    virtual int underflow();
    virtual int overflow(int c = EOF);
};

struct __file_fields {
    short _fileno;
    int _blksize;
    fpos_t _offset;
//    char* _save_gptr;  char* _save_egptr;
};

class filebuf : public backupbuf {
  protected:
    struct __file_fields _fb;
    void init();
  public:
    static const int openprot; // Non-ANSI AT&T-ism:  Default open protection.
    filebuf();
    filebuf(int fd);
    filebuf(int fd, char* p, int len);
    ~filebuf();
    filebuf* attach(int fd);
    filebuf* open(const char *filename, const char *mode);
    filebuf* open(const char *filename, ios::openmode mode, int prot = 0664);
    virtual int underflow();
    virtual int overflow(int c = EOF);
    int is_open() const { return _fb._fileno >= 0; }
    int fd() const { return is_open() ? _fb._fileno : EOF; }
    filebuf* close();
    virtual int doallocate();
    virtual streampos seekoff(streamoff, _seek_dir, int mode=ios::in|ios::out);
    virtual streambuf* setbuf(char* p, int len);
    int xsputn(const char* s, int n);
    int xsgetn(char* s, int n);
    virtual int sync();
  protected: // See documentation in filebuf.C.
//    virtual int pbackfail(int c);
    int is_reading() { return eback() != egptr(); }
    char* cur_ptr() { return is_reading() ?  gptr() : pptr(); }
    /* System's idea of pointer */
    char* file_ptr() { return eGptr(); }
    int do_write(const char *data, int to_do);
    int do_flush() { return do_write(_pbase, _pptr-_pbase); }
    // Low-level operations (Usually invoke system calls.)
    virtual _G_ssize_t sys_read(char* buf, _G_size_t size);
    virtual fpos_t sys_seek(fpos_t, _seek_dir);
    virtual _G_ssize_t sys_write(const void*, long);
    virtual int sys_stat(void*); // Actually, a (struct stat*)
    virtual int sys_close();
};

inline ios::ios(streambuf* sb /* = 0 */, ostream* tie /* = 0 */) {
		_state = sb ? ios::goodbit : ios::badbit; _exceptions=0;
		_strbuf=sb; _tie = tie; _width=0; _fill=' ';
		_flags=ios::skipws|ios::dec; _precision=6; }
inline ios::~ios() {
    if (!(_flags & (unsigned int)ios::dont_close)) delete _strbuf; }

#endif /* _STREAMBUF_H */