edit.c

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	    if (t) {
		memcpy (t, edit->undo_stack, sizeof (long) * edit->stack_size);
		free (edit->undo_stack);
		edit->undo_stack = t;
		edit->stack_size <<= 1;
		edit->stack_size_mask = edit->stack_size - 1;
	    }
	}
    }
    spm1 = (edit->stack_pointer - 1) & edit->stack_size_mask;
    if (push_action_disabled)
	return;

#ifdef FAST_MOVE_CURSOR
    if (c == CURS_LEFT_LOTS || c == CURS_RIGHT_LOTS) {
	va_list ap;
	edit->undo_stack[sp] = c == CURS_LEFT_LOTS ? CURS_LEFT : CURS_RIGHT;
	edit->stack_pointer = (edit->stack_pointer + 1) & edit->stack_size_mask;
	va_start (ap, c);
	c = -(va_arg (ap, int));
	va_end (ap);
    } else
#endif				/* ! FAST_MOVE_CURSOR */
    if (spm1 != edit->stack_bottom && ((sp - 2) & edit->stack_size_mask) != edit->stack_bottom) {
	int d;
	if (edit->undo_stack[spm1] < 0) {
	    d = edit->undo_stack[(sp - 2) & edit->stack_size_mask];
	    if (d == c) {
		if (edit->undo_stack[spm1] > -1000000000) {
		    if (c < KEY_PRESS)	/* --> no need to push multiple do-nothings */
			edit->undo_stack[spm1]--;
		    return;
		}
	    }
/* #define NO_STACK_CURSMOVE_ANIHILATION */
#ifndef NO_STACK_CURSMOVE_ANIHILATION
	    else if ((c == CURS_LEFT && d == CURS_RIGHT)
		     || (c == CURS_RIGHT && d == CURS_LEFT)) {	/* a left then a right anihilate each other */
		if (edit->undo_stack[spm1] == -2)
		    edit->stack_pointer = spm1;
		else
		    edit->undo_stack[spm1]++;
		return;
	    }
#endif
	} else {
	    d = edit->undo_stack[spm1];
	    if (d == c) {
		if (c >= KEY_PRESS)
		    return;	/* --> no need to push multiple do-nothings */
		edit->undo_stack[sp] = -2;
		goto check_bottom;
	    }
#ifndef NO_STACK_CURSMOVE_ANIHILATION
	    else if ((c == CURS_LEFT && d == CURS_RIGHT)
		     || (c == CURS_RIGHT && d == CURS_LEFT)) {	/* a left then a right anihilate each other */
		edit->stack_pointer = spm1;
		return;
	    }
#endif
	}
    }
    edit->undo_stack[sp] = c;
  check_bottom:

    edit->stack_pointer = (edit->stack_pointer + 1) & edit->stack_size_mask;

/*if the sp wraps round and catches the stack_bottom then erase the first set of actions on the stack to make space - by moving stack_bottom forward one "key press" */
    c = (edit->stack_pointer + 2) & edit->stack_size_mask;
    if (c == edit->stack_bottom || ((c + 1) & edit->stack_size_mask) == edit->stack_bottom)
	do {
	    edit->stack_bottom = (edit->stack_bottom + 1) & edit->stack_size_mask;
	} while (edit->undo_stack[edit->stack_bottom] < KEY_PRESS && edit->stack_bottom != edit->stack_pointer);

/*If a single key produced enough pushes to wrap all the way round then we would notice that the [stack_bottom] does not contain KEY_PRESS. The stack is then initialised: */
    if (edit->stack_pointer != edit->stack_bottom && edit->undo_stack[edit->stack_bottom] < KEY_PRESS)
	edit->stack_bottom = edit->stack_pointer = 0;
}

/*
   TODO: if the user undos until the stack bottom, and the stack has not wrapped,
   then the file should be as it was when he loaded up. Then set edit->modified to 0.
 */
long pop_action (WEdit * edit)
{
    long c;
    unsigned long sp = edit->stack_pointer;
    if (sp == edit->stack_bottom) {
	return STACK_BOTTOM;
    }
    sp = (sp - 1) & edit->stack_size_mask;
    if ((c = edit->undo_stack[sp]) >= 0) {
/*	edit->undo_stack[sp] = '@'; */
	edit->stack_pointer = (edit->stack_pointer - 1) & edit->stack_size_mask;
	return c;
    }
    if (sp == edit->stack_bottom) {
	return STACK_BOTTOM;
    }
    c = edit->undo_stack[(sp - 1) & edit->stack_size_mask];
    if (edit->undo_stack[sp] == -2) {
/*      edit->undo_stack[sp] = '@'; */
	edit->stack_pointer = sp;
    } else
	edit->undo_stack[sp]++;

    return c;
}


/* is called whenever a modification is made by one of the four routines below */
static inline void edit_modification (WEdit * edit)
{
    edit->modified = 1;
}


/*
   Basic low level single character buffer alterations and movements at the cursor.
   Returns char passed over, inserted or removed.
 */

void edit_insert (WEdit * edit, int c)
{
/* check if file has grown to large */
    if (edit->last_byte >= SIZE_LIMIT)
	return;

/* first we must update the position of the display window */
    if (edit->curs1 < edit->start_display) {
	edit->start_display++;
	if (c == '\n')
	    edit->start_line++;
    }
/* now we must update some info on the file and check if a redraw is required */
    if (c == '\n') {
	edit->curs_line++;
	edit->total_lines++;
	edit->force |= REDRAW_LINE_ABOVE | REDRAW_AFTER_CURSOR;
    }
/* tell that we've modified the file */
    edit_modification (edit);

/* save the reverse command onto the undo stack */
    edit_push_action (edit, BACKSPACE);

/* update markers */
    edit->mark1 += (edit->mark1 > edit->curs1);
    edit->mark2 += (edit->mark2 > edit->curs1);
    edit->last_get_rule += (edit->last_get_rule > edit->curs1);

/* add a new buffer if we've reached the end of the last one */
    if (!(edit->curs1 & M_EDIT_BUF_SIZE))
	edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE] = malloc (EDIT_BUF_SIZE);

/* perfprm the insertion */
    edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE][edit->curs1 & M_EDIT_BUF_SIZE] = (unsigned char) c;

/* update file length */
    edit->last_byte++;

/* update cursor position */
    edit->curs1++;
}


/* same as edit_insert and move left */
void edit_insert_ahead (WEdit * edit, int c)
{
    if (edit->last_byte >= SIZE_LIMIT)
	return;
    if (edit->curs1 < edit->start_display) {
	edit->start_display++;
	if (c == '\n')
	    edit->start_line++;
    }
    if (c == '\n') {
	edit->total_lines++;
	edit->force |= REDRAW_AFTER_CURSOR;
    }
    edit_modification (edit);
    edit_push_action (edit, DELETE);

    edit->mark1 += (edit->mark1 >= edit->curs1);
    edit->mark2 += (edit->mark2 >= edit->curs1);
    edit->last_get_rule += (edit->last_get_rule >= edit->curs1);

    if (!((edit->curs2 + 1) & M_EDIT_BUF_SIZE))
	edit->buffers2[(edit->curs2 + 1) >> S_EDIT_BUF_SIZE] = malloc (EDIT_BUF_SIZE);
    edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE][EDIT_BUF_SIZE - (edit->curs2 & M_EDIT_BUF_SIZE) - 1] = c;

    edit->last_byte++;
    edit->curs2++;
}


int edit_delete (WEdit * edit)
{
    int p;
    if (!edit->curs2)
	return 0;

    edit->mark1 -= (edit->mark1 > edit->curs1);
    edit->mark2 -= (edit->mark2 > edit->curs1);
    edit->last_get_rule -= (edit->last_get_rule > edit->curs1);

    p = edit->buffers2[(edit->curs2 - 1) >> S_EDIT_BUF_SIZE][EDIT_BUF_SIZE - ((edit->curs2 - 1) & M_EDIT_BUF_SIZE) - 1];

    if (!(edit->curs2 & M_EDIT_BUF_SIZE)) {
	free (edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE]);
	edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE] = NULL;
    }
    edit->last_byte--;
    edit->curs2--;

    if (p == '\n') {
	edit->total_lines--;
	edit->force |= REDRAW_AFTER_CURSOR;
    }
    edit_push_action (edit, p + 256);
    if (edit->curs1 < edit->start_display) {
	edit->start_display--;
	if (p == '\n')
	    edit->start_line--;
    }
    edit_modification (edit);

    return p;
}


int edit_backspace (WEdit * edit)
{
    int p;
    if (!edit->curs1)
	return 0;

    edit->mark1 -= (edit->mark1 >= edit->curs1);
    edit->mark2 -= (edit->mark2 >= edit->curs1);
    edit->last_get_rule -= (edit->last_get_rule >= edit->curs1);

    p = *(edit->buffers1[(edit->curs1 - 1) >> S_EDIT_BUF_SIZE] + ((edit->curs1 - 1) & M_EDIT_BUF_SIZE));
    if (!((edit->curs1 - 1) & M_EDIT_BUF_SIZE)) {
	free (edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE]);
	edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE] = NULL;
    }
    edit->last_byte--;
    edit->curs1--;

    if (p == '\n') {
	edit->curs_line--;
	edit->total_lines--;
	edit->force |= REDRAW_AFTER_CURSOR;
    }
    edit_push_action (edit, p);

    if (edit->curs1 < edit->start_display) {
	edit->start_display--;
	if (p == '\n')
	    edit->start_line--;
    }
    edit_modification (edit);

    return p;
}

#ifdef FAST_MOVE_CURSOR

#define memqcpy(edit,d,s,i)						\
	{								\
	    unsigned long next;						\
	    char *dest = d;						\
	    char *src = s;						\
	    int n = i;							\
	    while ((next =						\
		    (unsigned long) memccpy (dest, src, '\n', n))) {	\
		edit->curs_line--;					\
		next -= (unsigned long) dest;				\
		n -= next;						\
		src += next;						\
		dest += next;						\
	    }								\
	}

int edit_move_backward_lots (WEdit * edit, long increment)
{
    int r, s, t;
    char *p;

    if (increment > edit->curs1)
	increment = edit->curs1;
    if (increment <= 0)
	return -1;
    edit_push_action (edit, CURS_RIGHT_LOTS, increment);

    t = r = EDIT_BUF_SIZE - (edit->curs2 & M_EDIT_BUF_SIZE);
    if (r > increment)
	r = increment;
    s = edit->curs1 & M_EDIT_BUF_SIZE;

    p = 0;
    if (s > r) {
	memqcpy (edit, edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE] + t - r,
	      edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE] + s - r, r);
    } else {
	if (s) {
	    memqcpy (edit, edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE] + t - s,
		     edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE], s);
	    p = edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE];
	    edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE] = 0;
	}
	memqcpy (edit, edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE] + t - r,
		 edit->buffers1[(edit->curs1 >> S_EDIT_BUF_SIZE) - 1] + EDIT_BUF_SIZE - (r - s), r - s);
    }
    increment -= r;
    edit->curs1 -= r;
    edit->curs2 += r;
    if (!(edit->curs2 & M_EDIT_BUF_SIZE)) {
	if (p)
	    edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE] = p;
	else
	    edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE] = malloc (EDIT_BUF_SIZE);
    } else {
	if (p)
	    free (p);
    }

    s = edit->curs1 & M_EDIT_BUF_SIZE;
    while (increment) {
	p = 0;
	r = EDIT_BUF_SIZE;
	if (r > increment)
	    r = increment;
	t = s;
	if (r < t)
	    t = r;
	memqcpy (edit,
		 edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE] + EDIT_BUF_SIZE - t,
		 edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE] + s - t,
		 t);
	if (r >= s) {
	    if (t) {
		p = edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE];
		edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE] = 0;
	    }
	    memqcpy (edit,
		     edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE] + EDIT_BUF_SIZE - r,
		     edit->buffers1[(edit->curs1 >> S_EDIT_BUF_SIZE) - 1] + EDIT_BUF_SIZE - (r - s),
		     r - s);
	}
	increment -= r;
	edit->curs1 -= r;
	edit->curs2 += r;
	if (!(edit->curs2 & M_EDIT_BUF_SIZE)) {
	    if (p)
		edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE] = p;
	    else
		edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE] = malloc (EDIT_BUF_SIZE);
	} else {
	    if (p)
		free (p);
	}
    }
    return edit_get_byte (edit, edit->curs1);
}

#endif		/* ! FAST_MOVE_CURSOR */

/* moves the curser right or left: increment positive or negative respectively */
int edit_cursor_move (WEdit * edit, long increment)
{
/* this is the same as a combination of two of the above routines, with only one push onto the undo stack */
    int c;

#ifdef FAST_MOVE_CURSOR
    if (increment < -256) {
	edit->force |= REDRAW_PAGE;
	return edit_move_backward_lots (edit, -increment);
    }
#endif		/* ! FAST_MOVE_CURSOR */

    if (increment < 0) {
	for (; increment < 0; increment++) {
	    if (!edit->curs1)
		return -1;

	    edit_push_action (edit, CURS_RIGHT);

	    c = edit_get_byte (edit, edit->curs1 - 1);
	    if (!((edit->curs2 + 1) & M_EDIT_BUF_SIZE))
		edit->buffers2[(edit->curs2 + 1) >> S_EDIT_BUF_SIZE] = malloc (EDIT_BUF_SIZE);
	    edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE][EDIT_BUF_SIZE - (edit->curs2 & M_EDIT_BUF_SIZE) - 1] = c;
	    edit->curs2++;
	    c = edit->buffers1[(edit->curs1 - 1) >> S_EDIT_BUF_SIZE][(edit->curs1 - 1) & M_EDIT_BUF_SIZE];
	    if (!((edit->curs1 - 1) & M_EDIT_BUF_SIZE)) {
		free (edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE]);
		edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE] = NULL;
	    }
	    edit->curs1--;
	    if (c == '\n') {
		edit->curs_line--;
		edit->force |= REDRAW_LINE_BELOW;
	    }
	}

	return c;
    } else if (increment > 0) {
	for (; increment > 0; increment--) {
	    if (!edit->curs2)
		return -2;

	    edit_push_action (edit, CURS_LEFT);

	    c = edit_get_byte (edit, edit->curs1);
	    if (!(edit->curs1 & M_EDIT_BUF_SIZE))
		edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE] = malloc (EDIT_BUF_SIZE);
	    edit->buffers1[edit->curs1 >> S_EDIT_BUF_SIZE][edit->curs1 & M_EDIT_BUF_SIZE] = c;
	    edit->curs1++;
	    c = edit->buffers2[(edit->curs2 - 1) >> S_EDIT_BUF_SIZE][EDIT_BUF_SIZE - ((edit->curs2 - 1) & M_EDIT_BUF_SIZE) - 1];
	    if (!(edit->curs2 & M_EDIT_BUF_SIZE)) {
		free (edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE]);
		edit->buffers2[edit->curs2 >> S_EDIT_BUF_SIZE] = 0;
	    }
	    edit->curs2--;
	    if (c == '\n') {
		edit->curs_line++;
		edit->force |= REDRAW_LINE_ABOVE;
	    }
	}
	return c;
    } else
	return -3;
}

/* These functions return positions relative to lines */

/* returns index of last char on line + 1 */
long edit_eol (WEdit * edit, long current)
{
    if (current < edit->last_byte) {
	for (;; current++)
#if 0
	    if (current == edit->last_byte || edit_get_byte (edit, current) == '\n')
#else
	    if (edit_get_byte (edit, current) == '\n')
#endif
		break;
    } else
	return edit->last_byte;
    return current;
}

/* returns index of first char on line */
long edit_bol (WEdit * edit, long current)
{
    if (current > 0) {