prim.c

早期freebsd实现

/*
 * Jump to a specified position in the file.
 */
jump_loc(pos)
	off_t pos;
{
	register int nline;
	off_t tpos;

	if ((nline = onscreen(pos)) >= 0) {
		/*
		 * The line is currently displayed.  
		 * Just scroll there.
		 */
		forw(nline, position(BOTTOM_PLUS_ONE), 0);
		return;
	}

	/*
	 * Line is not on screen.
	 * Seek to the desired location.
	 */
	if (ch_seek(pos)) {
		error("Cannot seek to that position");
		return;
	}

	/*
	 * See if the desired line is BEFORE the currently displayed screen.
	 * If so, then move forward far enough so the line we're on will be
	 * at the bottom of the screen, in order to be able to call back()
	 * to make the screen scroll backwards & put the line at the top of
	 * the screen.
	 * {{ This seems inefficient, but it's not so bad,
	 *    since we can never move forward more than a
	 *    screenful before we stop to redraw the screen. }}
	 */
	tpos = position(TOP);
	if (tpos != NULL_POSITION && pos < tpos) {
		off_t npos = pos;
		/*
		 * Note that we can't forw_line() past tpos here,
		 * so there should be no EOI at this stage.
		 */
		for (nline = 0;  npos < tpos && nline < sc_height - 1;  nline++)
			npos = forw_line(npos);

		if (npos < tpos) {
			/*
			 * More than a screenful back.
			 */
			lastmark();
			clear();
			pos_clear();
			add_back_pos(npos);
		}

		/*
		 * Note that back() will repaint() if nline > back_scroll.
		 */
		back(nline, npos, 0);
		return;
	}
	/*
	 * Remember where we were; clear and paint the screen.
	 */
	lastmark();
	prepaint(pos);
}

/*
 * The table of marks.
 * A mark is simply a position in the file.
 */
#define	NMARKS		(27)		/* 26 for a-z plus one for quote */
#define	LASTMARK	(NMARKS-1)	/* For quote */
static off_t marks[NMARKS];

/*
 * Initialize the mark table to show no marks are set.
 */
init_mark()
{
	int i;

	for (i = 0;  i < NMARKS;  i++)
		marks[i] = NULL_POSITION;
}

/*
 * See if a mark letter is valid (between a and z).
 */
	static int
badmark(c)
	int c;
{
	if (c < 'a' || c > 'z')
	{
		error("Choose a letter between 'a' and 'z'");
		return (1);
	}
	return (0);
}

/*
 * Set a mark.
 */
setmark(c)
	int c;
{
	if (badmark(c))
		return;
	marks[c-'a'] = position(TOP);
}

lastmark()
{
	marks[LASTMARK] = position(TOP);
}

/*
 * Go to a previously set mark.
 */
gomark(c)
	int c;
{
	off_t pos;

	if (c == '\'') {
		pos = marks[LASTMARK];
		if (pos == NULL_POSITION)
			pos = 0;
	}
	else {
		if (badmark(c))
			return;
		pos = marks[c-'a'];
		if (pos == NULL_POSITION) {
			error("mark not set");
			return;
		}
	}
	jump_loc(pos);
}

/*
 * Get the backwards scroll limit.
 * Must call this function instead of just using the value of
 * back_scroll, because the default case depends on sc_height and
 * top_scroll, as well as back_scroll.
 */
get_back_scroll()
{
	if (back_scroll >= 0)
		return (back_scroll);
	if (top_scroll)
		return (sc_height - 2);
	return (sc_height - 1);
}

/*
 * Search for the n-th occurence of a specified pattern, 
 * either forward or backward.
 */
search(search_forward, pattern, n, wantmatch)
	register int search_forward;
	register char *pattern;
	register int n;
	int wantmatch;
{
	off_t pos, linepos;
	register char *p;
	register char *q;
	int linenum;
	int linematch;
#ifdef RECOMP
	char *re_comp();
	char *errmsg;
#else
#ifdef REGCMP
	char *regcmp();
	static char *cpattern = NULL;
#else
	static char lpbuf[100];
	static char *last_pattern = NULL;
	char *strcpy();
#endif
#endif

	/*
	 * For a caseless search, convert any uppercase in the pattern to
	 * lowercase.
	 */
	if (caseless && pattern != NULL)
		for (p = pattern;  *p;  p++)
			if (isupper(*p))
				*p = tolower(*p);
#ifdef RECOMP

	/*
	 * (re_comp handles a null pattern internally, 
	 *  so there is no need to check for a null pattern here.)
	 */
	if ((errmsg = re_comp(pattern)) != NULL)
	{
		error(errmsg);
		return(0);
	}
#else
#ifdef REGCMP
	if (pattern == NULL || *pattern == '\0')
	{
		/*
		 * A null pattern means use the previous pattern.
		 * The compiled previous pattern is in cpattern, so just use it.
		 */
		if (cpattern == NULL)
		{
			error("No previous regular expression");
			return(0);
		}
	} else
	{
		/*
		 * Otherwise compile the given pattern.
		 */
		char *s;
		if ((s = regcmp(pattern, 0)) == NULL)
		{
			error("Invalid pattern");
			return(0);
		}
		if (cpattern != NULL)
			free(cpattern);
		cpattern = s;
	}
#else
	if (pattern == NULL || *pattern == '\0')
	{
		/*
		 * Null pattern means use the previous pattern.
		 */
		if (last_pattern == NULL)
		{
			error("No previous regular expression");
			return(0);
		}
		pattern = last_pattern;
	} else
	{
		(void)strcpy(lpbuf, pattern);
		last_pattern = lpbuf;
	}
#endif
#endif

	/*
	 * Figure out where to start the search.
	 */

	if (position(TOP) == NULL_POSITION) {
		/*
		 * Nothing is currently displayed.  Start at the beginning
		 * of the file.  (This case is mainly for searches from the
		 * command line.
		 */
		pos = (off_t)0;
	} else if (!search_forward) {
		/*
		 * Backward search: start just before the top line
		 * displayed on the screen.
		 */
		pos = position(TOP);
	} else {
		/*
		 * Start at the second screen line displayed on the screen.
		 */
		pos = position(TOP_PLUS_ONE);
	}

	if (pos == NULL_POSITION)
	{
		/*
		 * Can't find anyplace to start searching from.
		 */
		error("Nothing to search");
		return(0);
	}

	linenum = find_linenum(pos);
	for (;;)
	{
		/*
		 * Get lines until we find a matching one or 
		 * until we hit end-of-file (or beginning-of-file 
		 * if we're going backwards).
		 */
		if (sigs)
			/*
			 * A signal aborts the search.
			 */
			return(0);

		if (search_forward)
		{
			/*
			 * Read the next line, and save the 
			 * starting position of that line in linepos.
			 */
			linepos = pos;
			pos = forw_raw_line(pos);
			if (linenum != 0)
				linenum++;
		} else
		{
			/*
			 * Read the previous line and save the
			 * starting position of that line in linepos.
			 */
			pos = back_raw_line(pos);
			linepos = pos;
			if (linenum != 0)
				linenum--;
		}

		if (pos == NULL_POSITION)
		{
			/*
			 * We hit EOF/BOF without a match.
			 */
			error("Pattern not found");
			return(0);
		}

		/*
		 * If we're using line numbers, we might as well
		 * remember the information we have now (the position
		 * and line number of the current line).
		 */
		if (linenums)
			add_lnum(linenum, pos);

		/*
		 * If this is a caseless search, convert uppercase in the
		 * input line to lowercase.
		 */
		if (caseless)
			for (p = q = line;  *p;  p++, q++)
				*q = isupper(*p) ? tolower(*p) : *p;

		/*
		 * Remove any backspaces along with the preceeding char.
		 * This allows us to match text which is underlined or
		 * overstruck.
		 */
		for (p = q = line;  *p;  p++, q++)
			if (q > line && *p == '\b')
				/* Delete BS and preceeding char. */
				q -= 2;
			else
				/* Otherwise, just copy. */
				*q = *p;

		/*
		 * Test the next line to see if we have a match.
		 * This is done in a variety of ways, depending
		 * on what pattern matching functions are available.
		 */
#ifdef REGCMP
		linematch = (regex(cpattern, line) != NULL);
#else
#ifdef RECOMP
		linematch = (re_exec(line) == 1);
#else
		linematch = match(pattern, line);
#endif
#endif
		/*
		 * We are successful if wantmatch and linematch are
		 * both true (want a match and got it),
		 * or both false (want a non-match and got it).
		 */
		if (((wantmatch && linematch) || (!wantmatch && !linematch)) &&
		      --n <= 0)
			/*
			 * Found the line.
			 */
			break;
	}
	jump_loc(linepos);
	return(1);
}

#if !defined(REGCMP) && !defined(RECOMP)
/*
 * We have neither regcmp() nor re_comp().
 * We use this function to do simple pattern matching.
 * It supports no metacharacters like *, etc.
 */
static
match(pattern, buf)
	char *pattern, *buf;
{
	register char *pp, *lp;

	for ( ;  *buf != '\0';  buf++)
	{
		for (pp = pattern, lp = buf;  *pp == *lp;  pp++, lp++)
			if (*pp == '\0' || *lp == '\0')
				break;
		if (*pp == '\0')
			return (1);
	}
	return (0);
}
#endif