editbuf.c

早期freebsd实现

//    This is part of the iostream library, providing input/output for C++.
//    Copyright (C) 1991 Per Bothner.
//
//    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, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

#include "ioprivate.h"
#include "editbuf.h"
#include <stddef.h>
#ifdef __GNUG__
#pragma implementation
#endif

/* NOTE: Some of the code here is taken from GNU emacs */
/* Hence this file falls under the GNU License! */

// Invariants for edit_streambuf:
// An edit_streambuf is associated with a specific edit_string,
// which again is a sub-string of a specific edit_buffer.
// An edit_streambuf is always in either get mode or put mode, never both.
// In get mode, gptr() is the current position,
// and pbase(), pptr(), and epptr() are all NULL.
// In put mode, pptr() is the current position,
// and eback(), gptr(), and egptr() are all NULL.
// Any edit_streambuf that is actively doing insertion (as opposed to
// replacing) // must have its pptr() pointing to the start of the gap.
// Only one edit_streambuf can be actively inserting into a specific
// edit_buffer; the edit_buffer's _writer field points to that edit_streambuf.
// That edit_streambuf "owns" the gap, and the actual start of the
// gap is the pptr() of the edit_streambuf; the edit_buffer::_gap_start pointer
// will only be updated on an edit_streambuf::overflow().

int edit_streambuf::truncate()
{
    str->buffer->delete_range(str->buffer->tell((buf_char*)pptr()),
			      str->buffer->tell(str->end));
    return 0;
}

#ifdef OLD_STDIO
inline void  disconnect_gap_from_file(edit_buffer* buffer, FILE* fp)
{
    if (buffer->gap_start_ptr != &fp->__bufp)
	return;
    buffer->gap_start_normal = fp->__bufp;
    buffer->gap_start_ptr = &buffer->gap_start_normal;
}
#endif

void edit_streambuf::flush_to_buffer(edit_buffer* buffer)
{
    if (pptr() > buffer->_gap_start && pptr() < buffer->gap_end())
	buffer->_gap_start = pptr();
}

void edit_streambuf::disconnect_gap_from_file(edit_buffer* buffer)
{
    if (buffer->_writer != this) return;
    flush_to_buffer(buffer);
    setp(pptr(),pptr());
    buffer->_writer = NULL;    
}

buf_index edit_buffer::tell(buf_char *ptr)
{
    if (ptr <= gap_start())
	return ptr - data;
    else
	return ptr - gap_end() + size1();
}

#if 0
buf_index buf_cookie::tell()
{
    return str->buffer->tell(file->__bufp);
}
#endif

buf_index edit_buffer::tell(edit_mark*mark)
{
    return tell(data + mark->index_in_buffer(this));
}

// adjust the position of the gap

void edit_buffer::move_gap(buf_offset pos)
{
  if (pos < size1())
    gap_left (pos);
  else if (pos > size1())
    gap_right (pos);
}

void edit_buffer::gap_left (int pos)
{
  register buf_char *to, *from;
  register int i;
  int new_s1;

  i = size1();
  from = gap_start();
  to = from + gap_size();
  new_s1 = size1();

  /* Now copy the characters.  To move the gap down,
     copy characters up.  */

  for (;;)
    {
      /* I gets number of characters left to copy.  */
      i = new_s1 - pos;
      if (i == 0)
	break;
#if 0
      /* If a quit is requested, stop copying now.
	 Change POS to be where we have actually moved the gap to.  */
      if (QUITP)
	{
	  pos = new_s1;
	  break;
	}
#endif
      /* Move at most 32000 chars before checking again for a quit.  */
      if (i > 32000)
	i = 32000;
      new_s1 -= i;
      while (--i >= 0)
	*--to = *--from;
    }

  /* Adjust markers, and buffer data structure, to put the gap at POS.
     POS is where the loop above stopped, which may be what was specified
     or may be where a quit was detected.  */
  adjust_markers (pos << 1, size1() << 1, gap_size(), data);
#ifndef OLD_STDIO
  _gap_start = data + pos;
#else
  if (gap_start_ptr == &gap_start_normal)
	gap_start_normal = data + pos;
#endif
  __gap_end_pos = to - data;
/*  QUIT;*/
}

void edit_buffer::gap_right (int pos)
{
  register buf_char *to, *from;
  register int i;
  int new_s1;

  i = size1();
  to = gap_start();
  from = i + gap_end();
  new_s1 = i;

  /* Now copy the characters.  To move the gap up,
     copy characters down.  */

  while (1)
    {
      /* I gets number of characters left to copy.  */
      i = pos - new_s1;
      if (i == 0)
	break;
#if 0
      /* If a quit is requested, stop copying now.
	 Change POS to be where we have actually moved the gap to.  */
      if (QUITP)
	{
	  pos = new_s1;
	  break;
	}
#endif
      /* Move at most 32000 chars before checking again for a quit.  */
      if (i > 32000)
	i = 32000;
      new_s1 += i;
      while (--i >= 0)
	*to++ = *from++;
    }

  adjust_markers ((size1() + gap_size()) << 1, (pos + gap_size()) << 1,
	- gap_size(), data);
#ifndef OLD_STDIO
  _gap_start = data+pos;
#else
  if (gap_start_ptr == &gap_start_normal)
	gap_start_normal = data + pos;
#endif
  __gap_end_pos = from - data;
/*  QUIT;*/
}

/* make sure that the gap in the current buffer is at least k
   characters wide */

void edit_buffer::make_gap(buf_offset k)
{
  register buf_char *p1, *p2, *lim;
  buf_char *old_data = data;
  int s1 = size1();

  if (gap_size() >= k)
    return;

  /* Get more than just enough */
  if (buf_size > 1000) k += 2000;
  else k += /*200;*/ 20; // for testing!

  p1 = (buf_char *) realloc (data, s1 + size2() + k);
  if (p1 == 0)
    abort(); /*memory_full ();*/

  k -= gap_size();			/* Amount of increase.  */

  /* Record new location of text */
  data = p1;

  /* Transfer the new free space from the end to the gap
     by shifting the second segment upward */
  p2 = data + buf_size;
  p1 = p2 + k;
  lim = p2 - size2();
  while (lim < p2)
    *--p1 = *--p2;

  /* Finish updating text location data */
  __gap_end_pos += k;

#ifndef OLD_STDIO
  _gap_start = data + s1;
#else
  if (gap_start_ptr == &gap_start_normal)
	gap_start_normal = data + s1;
#endif

  /* adjust markers */
  adjust_markers (s1 << 1, (buf_size << 1) + 1, k, old_data);
  buf_size += k;
}

/* Add `amount' to the position of every marker in the current buffer
   whose current position is between `from' (exclusive) and `to' (inclusive).
   Also, any markers past the outside of that interval, in the direction
   of adjustment, are first moved back to the near end of the interval
   and then adjusted by `amount'.  */

void edit_buffer::adjust_markers(register mark_pointer low,
				 register mark_pointer high,
				 int amount, buf_char *old_data)
{
  register struct edit_mark *m;
  register mark_pointer mpos;
  /* convert to mark_pointer */
  amount <<= 1;

  if (_writer)
      _writer->disconnect_gap_from_file(this);

  for (m = mark_list(); m != NULL; m = m->chain)
    {
      mpos = m->_pos;
      if (amount > 0)
	{
	  if (mpos > high && mpos < high + amount)
	    mpos = high + amount;
	}
      else
	{
	  if (mpos > low + amount && mpos <= low)
	    mpos = low + amount;
	}
      if (mpos > low && mpos <= high)
	mpos += amount;
      m->_pos = mpos;
    }

    // Now adjust files
    edit_streambuf *file;

    for (file = files; file != NULL; file = file->next) {
	mpos = file->current() - old_data;
	if (amount > 0)
	{
	  if (mpos > high && mpos < high + amount)
	    mpos = high + amount;
	}
	else
	{
	  if (mpos > low + amount && mpos <= low)
	    mpos = low + amount;
	}
	if (mpos > low && mpos <= high)
	    mpos += amount;
	char* new_pos = data + mpos;
	file->set_current(new_pos, file->is_reading());
    }
}

#if 0
stdio_
   __off == index at start of buffer (need only be valid after seek ? )
   __buf ==

if read/read_delete/overwrite mode:
     __endp <= min(*gap_start_ptr, edit_string->end->ptr(buffer))

if inserting:
     must have *gap_start_ptr == __bufp && *gap_start_ptr+gap == __endp
     file->edit_string->end->ptr(buffer) == *gap_start_ptr+end
if write_mode:
     if before gap
#endif

int edit_streambuf::underflow()
{
    if (!(_mode & ios::in))
	return EOF;
    struct edit_buffer *buffer = str->buffer;
    if (!is_reading()) { // Must switch from put to get mode.
	disconnect_gap_from_file(buffer);
	set_current(pptr(), 1);
    }
    buf_char *str_end = str->end->ptr(buffer);
  retry:
    if (gptr() < egptr()) {
	return *gptr();
    }
    if ((buf_char*)gptr() == str_end)
	return EOF;
    if (str_end <= buffer->gap_start()) {
	setg(eback(), gptr(), str_end);
	goto retry;
    }
    if (gptr() < buffer->gap_start()) {
	setg(eback(), gptr(), buffer->gap_start());
	goto retry;
    }
    if (gptr() == buffer->gap_start()) {
	disconnect_gap_from_file(buffer);
//	fp->__offset += fp->__bufp - fp->__buffer;
	setg(buffer->gap_end(), buffer->gap_end(), str_end);
    }