display.c

UNIX下SH的实现源码

     int current_line, omax, nmax, inv_botlin;
{
  register char *ofd, *ols, *oe, *nfd, *nls, *ne;
  int temp, lendiff, wsatend, od, nd;
  int current_invis_chars;

  /* If we're at the right edge of a terminal that supports xn, we're
     ready to wrap around, so do so.  This fixes problems with knowing
     the exact cursor position and cut-and-paste with certain terminal
     emulators.  In this calculation, TEMP is the physical screen
     position of the cursor. */
  temp = _rl_last_c_pos - W_OFFSET(_rl_last_v_pos, visible_wrap_offset);
  if (temp == screenwidth && _rl_term_autowrap && !_rl_horizontal_scroll_mode
      && _rl_last_v_pos == current_line - 1)
    {
      if (new[0])
	putc (new[0], rl_outstream);
      else
	putc (' ', rl_outstream);
      _rl_last_c_pos = 1;		/* XXX */
      _rl_last_v_pos++;
      if (old[0] && new[0])
	old[0] = new[0];
    }
      
  /* Find first difference. */
  for (ofd = old, nfd = new;
       (ofd - old < omax) && *ofd && (*ofd == *nfd);
       ofd++, nfd++)
    ;

  /* Move to the end of the screen line.  ND and OD are used to keep track
     of the distance between ne and new and oe and old, respectively, to
     move a subtraction out of each loop. */
  for (od = ofd - old, oe = ofd; od < omax && *oe; oe++, od++);
  for (nd = nfd - new, ne = nfd; nd < nmax && *ne; ne++, nd++);

  /* If no difference, continue to next line. */
  if (ofd == oe && nfd == ne)
    return;

  wsatend = 1;			/* flag for trailing whitespace */
  ols = oe - 1;			/* find last same */
  nls = ne - 1;
  while ((ols > ofd) && (nls > nfd) && (*ols == *nls))
    {
      if (*ols != ' ')
	wsatend = 0;
      ols--;
      nls--;
    }

  if (wsatend)
    {
      ols = oe;
      nls = ne;
    }
  else if (*ols != *nls)
    {
      if (*ols)			/* don't step past the NUL */
	ols++;
      if (*nls)
	nls++;
    }

  /* count of invisible characters in the current invisible line. */
  current_invis_chars = W_OFFSET (current_line, wrap_offset);
  if (_rl_last_v_pos != current_line)
    {
      _rl_move_vert (current_line);
      if (current_line == 0 && visible_wrap_offset)
	_rl_last_c_pos += visible_wrap_offset;
    }

  /* If this is the first line and there are invisible characters in the
     prompt string, and the prompt string has not changed, and the current
     cursor position is before the last invisible character in the prompt,
     and the index of the character to move to is past the end of the prompt
     string, then redraw the entire prompt string.  We can only do this
     reliably if the terminal supports a `cr' capability.

     This is not an efficiency hack -- there is a problem with redrawing
     portions of the prompt string if they contain terminal escape
     sequences (like drawing the `unbold' sequence without a corresponding
     `bold') that manifests itself on certain terminals. */

  lendiff = local_prompt ? strlen (local_prompt) : 0;
  od = ofd - old;	/* index of first difference in visible line */
  if (current_line == 0 && !_rl_horizontal_scroll_mode &&
      term_cr && lendiff > visible_length && _rl_last_c_pos > 0 &&
      od > lendiff && _rl_last_c_pos < last_invisible)
    {
#if defined (__MSDOS__)
      putc ('\r', rl_outstream);
#else
      tputs (term_cr, 1, _rl_output_character_function);
#endif
      _rl_output_some_chars (local_prompt, lendiff);
      _rl_last_c_pos = lendiff;
    }

  _rl_move_cursor_relative (od, old);

  /* if (len (new) > len (old)) */
  lendiff = (nls - nfd) - (ols - ofd);

  /* If we are changing the number of invisible characters in a line, and
     the spot of first difference is before the end of the invisible chars,
     lendiff needs to be adjusted. */
  if (current_line == 0 && !_rl_horizontal_scroll_mode &&
      current_invis_chars != visible_wrap_offset)
    lendiff += visible_wrap_offset - current_invis_chars;

  /* Insert (diff (len (old), len (new)) ch. */
  temp = ne - nfd;
  if (lendiff > 0)
    {
      /* Non-zero if we're increasing the number of lines. */
      int gl = current_line >= _rl_vis_botlin && inv_botlin > _rl_vis_botlin;
      /* Sometimes it is cheaper to print the characters rather than
	 use the terminal's capabilities.  If we're growing the number
	 of lines, make sure we actually cause the new line to wrap
	 around on auto-wrapping terminals. */
      if (terminal_can_insert && ((2 * temp) >= lendiff || term_IC) && (!_rl_term_autowrap || !gl))
	{
	  /* If lendiff > visible_length and _rl_last_c_pos == 0 and
	     _rl_horizontal_scroll_mode == 1, inserting the characters with
	     term_IC or term_ic will screw up the screen because of the
	     invisible characters.  We need to just draw them. */
	  if (*ols && (!_rl_horizontal_scroll_mode || _rl_last_c_pos > 0 ||
			lendiff <= visible_length || !current_invis_chars))
	    {
	      insert_some_chars (nfd, lendiff);
	      _rl_last_c_pos += lendiff;
	    }
	  else if (*ols == 0)
	    {
	      /* At the end of a line the characters do not have to
		 be "inserted".  They can just be placed on the screen. */
	      /* However, this screws up the rest of this block, which
		 assumes you've done the insert because you can. */
	      _rl_output_some_chars (nfd, lendiff);
	      _rl_last_c_pos += lendiff;
	    }
	  else
	    {
	      /* We have horizontal scrolling and we are not inserting at
		 the end.  We have invisible characters in this line.  This
		 is a dumb update. */
	      _rl_output_some_chars (nfd, temp);
	      _rl_last_c_pos += temp;
	      return;
	    }
	  /* Copy (new) chars to screen from first diff to last match. */
	  temp = nls - nfd;
	  if ((temp - lendiff) > 0)
	    {
	      _rl_output_some_chars (nfd + lendiff, temp - lendiff);
	      _rl_last_c_pos += temp - lendiff;
	    }
	}
      else
	{
	  /* cannot insert chars, write to EOL */
	  _rl_output_some_chars (nfd, temp);
	  _rl_last_c_pos += temp;
	}
    }
  else				/* Delete characters from line. */
    {
      /* If possible and inexpensive to use terminal deletion, then do so. */
      if (term_dc && (2 * temp) >= -lendiff)
	{
	  /* If all we're doing is erasing the invisible characters in the
	     prompt string, don't bother.  It screws up the assumptions
	     about what's on the screen. */
	  if (_rl_horizontal_scroll_mode && _rl_last_c_pos == 0 &&
	      -lendiff == visible_wrap_offset)
	    lendiff = 0;

	  if (lendiff)
	    delete_chars (-lendiff); /* delete (diff) characters */

	  /* Copy (new) chars to screen from first diff to last match */
	  temp = nls - nfd;
	  if (temp > 0)
	    {
	      _rl_output_some_chars (nfd, temp);
	      _rl_last_c_pos += temp;
	    }
	}
      /* Otherwise, print over the existing material. */
      else
	{
	  if (temp > 0)
	    {
	      _rl_output_some_chars (nfd, temp);
	      _rl_last_c_pos += temp;
	    }
	  lendiff = (oe - old) - (ne - new);
	  if (lendiff)
	    {	  
	      if (_rl_term_autowrap && current_line < inv_botlin)
		space_to_eol (lendiff);
	      else
		_rl_clear_to_eol (lendiff);
	    }
	}
    }
}

/* Tell the update routines that we have moved onto a new (empty) line. */
int
rl_on_new_line ()
{
  if (visible_line)
    visible_line[0] = '\0';

  _rl_last_c_pos = _rl_last_v_pos = 0;
  _rl_vis_botlin = last_lmargin = 0;
  if (vis_lbreaks)
    vis_lbreaks[0] = vis_lbreaks[1] = 0;
  visible_wrap_offset = 0;
  return 0;
}

/* Tell the update routines that we have moved onto a new line with the
   prompt already displayed.  Code originally from the version of readline
   distributed with CLISP. */
int
rl_on_new_line_with_prompt ()
{
  int prompt_size, i, l, real_screenwidth, newlines;
  char *prompt_last_line;

  /* Initialize visible_line and invisible_line to ensure that they can hold
     the already-displayed prompt. */
  prompt_size = strlen (rl_prompt) + 1;
  init_line_structures (prompt_size);

  /* Make sure the line structures hold the already-displayed prompt for
     redisplay. */
  strcpy (visible_line, rl_prompt);
  strcpy (invisible_line, rl_prompt);

  /* If the prompt contains newlines, take the last tail. */
  prompt_last_line = strrchr (rl_prompt, '\n');
  if (!prompt_last_line)
    prompt_last_line = rl_prompt;

  l = strlen (prompt_last_line);
  _rl_last_c_pos = l;

  /* Dissect prompt_last_line into screen lines. Note that here we have
     to use the real screenwidth. Readline's notion of screenwidth might be
     one less, see terminal.c. */
  real_screenwidth = screenwidth + (_rl_term_autowrap ? 0 : 1);
  _rl_last_v_pos = l / real_screenwidth;
  /* If the prompt length is a multiple of real_screenwidth, we don't know
     whether the cursor is at the end of the last line, or already at the
     beginning of the next line. Output a newline just to be safe. */
  if (l > 0 && (l % real_screenwidth) == 0)
    _rl_output_some_chars ("\n", 1);
  last_lmargin = 0;

  newlines = 0; i = 0;
  while (i <= l)
    {
      _rl_vis_botlin = newlines;
      vis_lbreaks[newlines++] = i;
      i += real_screenwidth;
    }
  vis_lbreaks[newlines] = l;
  visible_wrap_offset = 0;

  return 0;
}

/* Actually update the display, period. */
int
rl_forced_update_display ()
{
  if (visible_line)
    {
      register char *temp = visible_line;

      while (*temp)
	*temp++ = '\0';
    }
  rl_on_new_line ();
  forced_display++;
  (*rl_redisplay_function) ();
  return 0;
}

/* Move the cursor from _rl_last_c_pos to NEW, which are buffer indices.
   DATA is the contents of the screen line of interest; i.e., where
   the movement is being done. */
void
_rl_move_cursor_relative (new, data)
     int new;
     char *data;
{
  register int i;

  /* If we don't have to do anything, then return. */
  if (_rl_last_c_pos == new) return;

  /* It may be faster to output a CR, and then move forwards instead
     of moving backwards. */
  /* i == current physical cursor position. */
  i = _rl_last_c_pos - W_OFFSET(_rl_last_v_pos, visible_wrap_offset);
  if (new == 0 || CR_FASTER (new, _rl_last_c_pos) ||
      (_rl_term_autowrap && i == screenwidth))
    {
#if defined (__MSDOS__)
      putc ('\r', rl_outstream);
#else
      tputs (term_cr, 1, _rl_output_character_function);
#endif /* !__MSDOS__ */
      _rl_last_c_pos = 0;
    }

  if (_rl_last_c_pos < new)
    {
      /* Move the cursor forward.  We do it by printing the command
	 to move the cursor forward if there is one, else print that
	 portion of the output buffer again.  Which is cheaper? */

      /* The above comment is left here for posterity.  It is faster
	 to print one character (non-control) than to print a control
	 sequence telling the terminal to move forward one character.
	 That kind of control is for people who don't know what the
	 data is underneath the cursor. */
#if defined (HACK_TERMCAP_MOTION)
      if (term_forward_char)
	for (i = _rl_last_c_pos; i < new; i++)
	  tputs (term_forward_char, 1, _rl_output_character_function);
      else
	for (i = _rl_last_c_pos; i < new; i++)
	  putc (data[i], rl_outstream);
#else
      for (i = _rl_last_c_pos; i < new; i++)
	putc (data[i], rl_outstream);
#endif /* HACK_TERMCAP_MOTION */
    }
  else if (_rl_last_c_pos > new)
    _rl_backspace (_rl_last_c_pos - new);
  _rl_last_c_pos = new;
}

/* PWP: move the cursor up or down. */
void
_rl_move_vert (to)
     int to;
{
  register int delta, i;

  if (_rl_last_v_pos == to || to > screenheight)
    return;

  if ((delta = to - _rl_last_v_pos) > 0)
    {
      for (i = 0; i < delta; i++)
	putc ('\n', rl_outstream);
#if defined (__MSDOS__)
      putc ('\r', rl_outstream);
#else
      tputs (term_cr, 1, _rl_output_character_function);
#endif
      _rl_last_c_pos = 0;
    }
  else
    {			/* delta < 0 */
#ifdef __MSDOS__
      int row, col;
      i = fflush (rl_outstream); /* make sure the cursor pos is current! */
      ScreenGetCursor (&row, &col);
      ScreenSetCursor ((row + to - _rl_last_v_pos), col);
      delta = i;
#else /* !__MSDOS__ */
      if (term_up && *term_up)
	for (i = 0; i < -delta; i++)
	  tputs (term_up, 1, _rl_output_character_function);
#endif /* !__MSDOS__ */
    }

  _rl_last_v_pos = to;		/* Now TO is here */
}

/* Physically print C on rl_outstream.  This is for functions which know
   how to optimize the display.  Return the number of characters output. */
int
rl_show_char (c)
     int c;
{
  int n = 1;
  if (META_CHAR (c) && (_rl_output_meta_chars == 0))
    {
      fprintf (rl_outstream, "M-");
      n += 2;
      c = UNMETA (c);
    }

#if defined (DISPLAY_TABS)
  if ((CTRL_CHAR (c) && c != '\t') || c == RUBOUT)
#else
  if (CTRL_CHAR (c) || c == RUBOUT)
#endif /* !DISPLAY_TABS */
    {
      fprintf (rl_outstream, "C-");
      n += 2;
      c = CTRL_CHAR (c) ? UNCTRL (c) : '?';
    }

  putc (c, rl_outstream);
  fflush (rl_outstream);
  return n;
}

int
rl_character_len (c, pos)
     register int c, pos;
{
  unsigned char uc;

  uc = (unsigned char)c;