xref: /freebsd/contrib/less/search.c (revision 830940567b49bb0c08dfaed40418999e76616909)
1 /* $FreeBSD$ */
2 /*
3  * Copyright (C) 1984-2009  Mark Nudelman
4  *
5  * You may distribute under the terms of either the GNU General Public
6  * License or the Less License, as specified in the README file.
7  *
8  * For more information about less, or for information on how to
9  * contact the author, see the README file.
10  */
11 
12 
13 /*
14  * Routines to search a file for a pattern.
15  */
16 
17 #include "less.h"
18 #include "pattern.h"
19 #include "position.h"
20 #include "charset.h"
21 
22 #define	MINPOS(a,b)	(((a) < (b)) ? (a) : (b))
23 #define	MAXPOS(a,b)	(((a) > (b)) ? (a) : (b))
24 
25 extern int sigs;
26 extern int how_search;
27 extern int caseless;
28 extern int linenums;
29 extern int sc_height;
30 extern int jump_sline;
31 extern int bs_mode;
32 extern int less_is_more;
33 extern int ctldisp;
34 extern int status_col;
35 extern void * constant ml_search;
36 extern POSITION start_attnpos;
37 extern POSITION end_attnpos;
38 extern int utf_mode;
39 extern int screen_trashed;
40 #if HILITE_SEARCH
41 extern int hilite_search;
42 extern int size_linebuf;
43 extern int squished;
44 extern int can_goto_line;
45 static int hide_hilite;
46 static POSITION prep_startpos;
47 static POSITION prep_endpos;
48 static int is_caseless;
49 static int is_ucase_pattern;
50 
51 struct hilite
52 {
53 	struct hilite *hl_next;
54 	POSITION hl_startpos;
55 	POSITION hl_endpos;
56 };
57 static struct hilite hilite_anchor = { NULL, NULL_POSITION, NULL_POSITION };
58 static struct hilite filter_anchor = { NULL, NULL_POSITION, NULL_POSITION };
59 #define	hl_first	hl_next
60 #endif
61 
62 /*
63  * These are the static variables that represent the "remembered"
64  * search pattern and filter pattern.
65  */
66 struct pattern_info {
67 	DEFINE_PATTERN(compiled);
68 	char* text;
69 	int search_type;
70 };
71 
72 static struct pattern_info search_info;
73 static struct pattern_info filter_info;
74 
75 /*
76  * Compile and save a search pattern.
77  */
78 	static int
79 set_pattern(info, pattern, search_type)
80 	struct pattern_info *info;
81 	char *pattern;
82 	int search_type;
83 {
84 	if (pattern == NULL)
85 		CLEAR_PATTERN(search_info.compiled);
86 	else if (compile_pattern(pattern, search_type, &info->compiled) < 0)
87 		return -1;
88 	/* Pattern compiled successfully; save the text too. */
89 	if (info->text != NULL)
90 		free(info->text);
91 	info->text = NULL;
92 	if (pattern != NULL)
93 	{
94 		info->text = (char *) ecalloc(1, strlen(pattern)+1);
95 		strcpy(info->text, pattern);
96 	}
97 	info->search_type = search_type;
98 	return 0;
99 }
100 
101 /*
102  * Discard a saved pattern.
103  */
104 	static void
105 clear_pattern(info)
106 	struct pattern_info *info;
107 {
108 	if (info->text != NULL)
109 		free(info->text);
110 	info->text = NULL;
111 	uncompile_pattern(&info->compiled);
112 }
113 
114 /*
115  * Initialize saved pattern to nothing.
116  */
117 	static void
118 init_pattern(info)
119 	struct pattern_info *info;
120 {
121 	CLEAR_PATTERN(info->compiled);
122 	info->text = NULL;
123 	info->search_type = 0;
124 }
125 
126 /*
127  * Initialize search variables.
128  */
129 	public void
130 init_search()
131 {
132 	init_pattern(&search_info);
133 	init_pattern(&filter_info);
134 }
135 
136 /*
137  * Determine which text conversions to perform before pattern matching.
138  */
139 	static int
140 get_cvt_ops()
141 {
142 	int ops = 0;
143 	if (is_caseless || bs_mode == BS_SPECIAL)
144 	{
145 		if (is_caseless)
146 			ops |= CVT_TO_LC;
147 		if (bs_mode == BS_SPECIAL)
148 			ops |= CVT_BS;
149 		if (bs_mode != BS_CONTROL)
150 			ops |= CVT_CRLF;
151 	} else if (bs_mode != BS_CONTROL)
152 	{
153 		ops |= CVT_CRLF;
154 	}
155 	if (ctldisp == OPT_ONPLUS)
156 		ops |= CVT_ANSI;
157 	return (ops);
158 }
159 
160 /*
161  * Are there any uppercase letters in this string?
162  */
163 	static int
164 is_ucase(str)
165 	char *str;
166 {
167 	char *str_end = str + strlen(str);
168 	LWCHAR ch;
169 
170 	while (str < str_end)
171 	{
172 		ch = step_char(&str, +1, str_end);
173 		if (IS_UPPER(ch))
174 			return (1);
175 	}
176 	return (0);
177 }
178 
179 /*
180  * Is there a previous (remembered) search pattern?
181  */
182 	static int
183 prev_pattern(info)
184 	struct pattern_info *info;
185 {
186 	if (info->search_type & SRCH_NO_REGEX)
187 		return (info->text != NULL);
188 	return (!is_null_pattern(info->compiled));
189 }
190 
191 #if HILITE_SEARCH
192 /*
193  * Repaint the hilites currently displayed on the screen.
194  * Repaint each line which contains highlighted text.
195  * If on==0, force all hilites off.
196  */
197 	public void
198 repaint_hilite(on)
199 	int on;
200 {
201 	int slinenum;
202 	POSITION pos;
203 	POSITION epos;
204 	int save_hide_hilite;
205 
206 	if (squished)
207 		repaint();
208 
209 	save_hide_hilite = hide_hilite;
210 	if (!on)
211 	{
212 		if (hide_hilite)
213 			return;
214 		hide_hilite = 1;
215 	}
216 
217 	if (!can_goto_line)
218 	{
219 		repaint();
220 		hide_hilite = save_hide_hilite;
221 		return;
222 	}
223 
224 	for (slinenum = TOP;  slinenum < TOP + sc_height-1;  slinenum++)
225 	{
226 		pos = position(slinenum);
227 		if (pos == NULL_POSITION)
228 			continue;
229 		epos = position(slinenum+1);
230 		(void) forw_line(pos);
231 		goto_line(slinenum);
232 		put_line();
233 	}
234 	lower_left(); // if !oldbot
235 	hide_hilite = save_hide_hilite;
236 }
237 
238 /*
239  * Clear the attn hilite.
240  */
241 	public void
242 clear_attn()
243 {
244 	int slinenum;
245 	POSITION old_start_attnpos;
246 	POSITION old_end_attnpos;
247 	POSITION pos;
248 	POSITION epos;
249 	int moved = 0;
250 
251 	if (start_attnpos == NULL_POSITION)
252 		return;
253 	old_start_attnpos = start_attnpos;
254 	old_end_attnpos = end_attnpos;
255 	start_attnpos = end_attnpos = NULL_POSITION;
256 
257 	if (!can_goto_line)
258 	{
259 		repaint();
260 		return;
261 	}
262 	if (squished)
263 		repaint();
264 
265 	for (slinenum = TOP;  slinenum < TOP + sc_height-1;  slinenum++)
266 	{
267 		pos = position(slinenum);
268 		if (pos == NULL_POSITION)
269 			continue;
270 		epos = position(slinenum+1);
271 		if (pos < old_end_attnpos &&
272 		     (epos == NULL_POSITION || epos > old_start_attnpos))
273 		{
274 			(void) forw_line(pos);
275 			goto_line(slinenum);
276 			put_line();
277 			moved = 1;
278 		}
279 	}
280 	if (moved)
281 		lower_left();
282 }
283 #endif
284 
285 /*
286  * Hide search string highlighting.
287  */
288 	public void
289 undo_search()
290 {
291 	if (!prev_pattern(&search_info))
292 	{
293 		error("No previous regular expression", NULL_PARG);
294 		return;
295 	}
296 #if HILITE_SEARCH
297 	hide_hilite = !hide_hilite;
298 	repaint_hilite(1);
299 #endif
300 }
301 
302 #if HILITE_SEARCH
303 /*
304  * Clear the hilite list.
305  */
306 	public void
307 clr_hlist(anchor)
308 	struct hilite *anchor;
309 {
310 	struct hilite *hl;
311 	struct hilite *nexthl;
312 
313 	for (hl = anchor->hl_first;  hl != NULL;  hl = nexthl)
314 	{
315 		nexthl = hl->hl_next;
316 		free((void*)hl);
317 	}
318 	anchor->hl_first = NULL;
319 	prep_startpos = prep_endpos = NULL_POSITION;
320 }
321 
322 	public void
323 clr_hilite()
324 {
325 	clr_hlist(&hilite_anchor);
326 }
327 
328 	public void
329 clr_filter()
330 {
331 	clr_hlist(&filter_anchor);
332 }
333 
334 /*
335  * Should any characters in a specified range be highlighted?
336  */
337 	static int
338 is_hilited_range(pos, epos)
339 	POSITION pos;
340 	POSITION epos;
341 {
342 	struct hilite *hl;
343 
344 	/*
345 	 * Look at each highlight and see if any part of it falls in the range.
346 	 */
347 	for (hl = hilite_anchor.hl_first;  hl != NULL;  hl = hl->hl_next)
348 	{
349 		if (hl->hl_endpos > pos &&
350 		    (epos == NULL_POSITION || epos > hl->hl_startpos))
351 			return (1);
352 	}
353 	return (0);
354 }
355 
356 /*
357  * Is a line "filtered" -- that is, should it be hidden?
358  */
359 	public int
360 is_filtered(pos)
361 	POSITION pos;
362 {
363 	struct hilite *hl;
364 
365 	if (ch_getflags() & CH_HELPFILE)
366 		return (0);
367 
368 	/*
369 	 * Look at each filter and see if the start position
370 	 * equals the start position of the line.
371 	 */
372 	for (hl = filter_anchor.hl_first;  hl != NULL;  hl = hl->hl_next)
373 	{
374 		if (hl->hl_startpos == pos)
375 			return (1);
376 	}
377 	return (0);
378 }
379 
380 /*
381  * Should any characters in a specified range be highlighted?
382  * If nohide is nonzero, don't consider hide_hilite.
383  */
384 	public int
385 is_hilited(pos, epos, nohide, p_matches)
386 	POSITION pos;
387 	POSITION epos;
388 	int nohide;
389 	int *p_matches;
390 {
391 	int match;
392 
393 	if (p_matches != NULL)
394 		*p_matches = 0;
395 
396 	if (!status_col &&
397 	    start_attnpos != NULL_POSITION &&
398 	    pos < end_attnpos &&
399 	     (epos == NULL_POSITION || epos > start_attnpos))
400 		/*
401 		 * The attn line overlaps this range.
402 		 */
403 		return (1);
404 
405 	match = is_hilited_range(pos, epos);
406 	if (!match)
407 		return (0);
408 
409 	if (p_matches != NULL)
410 		/*
411 		 * Report matches, even if we're hiding highlights.
412 		 */
413 		*p_matches = 1;
414 
415 	if (hilite_search == 0)
416 		/*
417 		 * Not doing highlighting.
418 		 */
419 		return (0);
420 
421 	if (!nohide && hide_hilite)
422 		/*
423 		 * Highlighting is hidden.
424 		 */
425 		return (0);
426 
427 	return (1);
428 }
429 
430 /*
431  * Add a new hilite to a hilite list.
432  */
433 	static void
434 add_hilite(anchor, hl)
435 	struct hilite *anchor;
436 	struct hilite *hl;
437 {
438 	struct hilite *ihl;
439 
440 	/*
441 	 * Hilites are sorted in the list; find where new one belongs.
442 	 * Insert new one after ihl.
443 	 */
444 	for (ihl = anchor;  ihl->hl_next != NULL;  ihl = ihl->hl_next)
445 	{
446 		if (ihl->hl_next->hl_startpos > hl->hl_startpos)
447 			break;
448 	}
449 
450 	/*
451 	 * Truncate hilite so it doesn't overlap any existing ones
452 	 * above and below it.
453 	 */
454 	if (ihl != anchor)
455 		hl->hl_startpos = MAXPOS(hl->hl_startpos, ihl->hl_endpos);
456 	if (ihl->hl_next != NULL)
457 		hl->hl_endpos = MINPOS(hl->hl_endpos, ihl->hl_next->hl_startpos);
458 	if (hl->hl_startpos >= hl->hl_endpos)
459 	{
460 		/*
461 		 * Hilite was truncated out of existence.
462 		 */
463 		free(hl);
464 		return;
465 	}
466 	hl->hl_next = ihl->hl_next;
467 	ihl->hl_next = hl;
468 }
469 
470 /*
471  * Make a hilite for each string in a physical line which matches
472  * the current pattern.
473  * sp,ep delimit the first match already found.
474  */
475 	static void
476 hilite_line(linepos, line, line_len, chpos, sp, ep, cvt_ops)
477 	POSITION linepos;
478 	char *line;
479 	int line_len;
480 	int *chpos;
481 	char *sp;
482 	char *ep;
483 	int cvt_ops;
484 {
485 	char *searchp;
486 	char *line_end = line + line_len;
487 	struct hilite *hl;
488 
489 	if (sp == NULL || ep == NULL)
490 		return;
491 	/*
492 	 * sp and ep delimit the first match in the line.
493 	 * Mark the corresponding file positions, then
494 	 * look for further matches and mark them.
495 	 * {{ This technique, of calling match_pattern on subsequent
496 	 *    substrings of the line, may mark more than is correct
497 	 *    if the pattern starts with "^".  This bug is fixed
498 	 *    for those regex functions that accept a notbol parameter
499 	 *    (currently POSIX, PCRE and V8-with-regexec2). }}
500 	 */
501 	searchp = line;
502 	do {
503 		if (ep > sp)
504 		{
505 			hl = (struct hilite *) ecalloc(1, sizeof(struct hilite));
506 			hl->hl_startpos = linepos + chpos[sp-line];
507 			hl->hl_endpos = linepos + chpos[ep-line];
508 			add_hilite(&hilite_anchor, hl);
509 		}
510 		/*
511 		 * If we matched more than zero characters,
512 		 * move to the first char after the string we matched.
513 		 * If we matched zero, just move to the next char.
514 		 */
515 		if (ep > searchp)
516 			searchp = ep;
517 		else if (searchp != line_end)
518 			searchp++;
519 		else /* end of line */
520 			break;
521 	} while (match_pattern(search_info.compiled, search_info.text,
522 			searchp, line_end - searchp, &sp, &ep, 1, search_info.search_type));
523 }
524 #endif
525 
526 /*
527  * Change the caseless-ness of searches.
528  * Updates the internal search state to reflect a change in the -i flag.
529  */
530 	public void
531 chg_caseless()
532 {
533 	if (!is_ucase_pattern)
534 		/*
535 		 * Pattern did not have uppercase.
536 		 * Just set the search caselessness to the global caselessness.
537 		 */
538 		is_caseless = caseless;
539 	else
540 		/*
541 		 * Pattern did have uppercase.
542 		 * Discard the pattern; we can't change search caselessness now.
543 		 */
544 		clear_pattern(&search_info);
545 }
546 
547 #if HILITE_SEARCH
548 /*
549  * Find matching text which is currently on screen and highlight it.
550  */
551 	static void
552 hilite_screen()
553 {
554 	struct scrpos scrpos;
555 
556 	get_scrpos(&scrpos);
557 	if (scrpos.pos == NULL_POSITION)
558 		return;
559 	prep_hilite(scrpos.pos, position(BOTTOM_PLUS_ONE), -1);
560 	repaint_hilite(1);
561 }
562 
563 /*
564  * Change highlighting parameters.
565  */
566 	public void
567 chg_hilite()
568 {
569 	/*
570 	 * Erase any highlights currently on screen.
571 	 */
572 	clr_hilite();
573 	hide_hilite = 0;
574 
575 	if (hilite_search == OPT_ONPLUS)
576 		/*
577 		 * Display highlights.
578 		 */
579 		hilite_screen();
580 }
581 #endif
582 
583 /*
584  * Figure out where to start a search.
585  */
586 	static POSITION
587 search_pos(search_type)
588 	int search_type;
589 {
590 	POSITION pos;
591 	int linenum;
592 
593 	if (empty_screen())
594 	{
595 		/*
596 		 * Start at the beginning (or end) of the file.
597 		 * The empty_screen() case is mainly for
598 		 * command line initiated searches;
599 		 * for example, "+/xyz" on the command line.
600 		 * Also for multi-file (SRCH_PAST_EOF) searches.
601 		 */
602 		if (search_type & SRCH_FORW)
603 		{
604 			return (ch_zero());
605 		} else
606 		{
607 			pos = ch_length();
608 			if (pos == NULL_POSITION)
609 			{
610 				(void) ch_end_seek();
611 				pos = ch_length();
612 			}
613 			return (pos);
614 		}
615 	}
616 	if (how_search)
617 	{
618 		/*
619 		 * Search does not include current screen.
620 		 */
621 		if (search_type & SRCH_FORW)
622 			linenum = BOTTOM_PLUS_ONE;
623 		else
624 			linenum = TOP;
625 		pos = position(linenum);
626 	} else
627 	{
628 		/*
629 		 * Search includes current screen.
630 		 * It starts at the jump target (if searching backwards),
631 		 * or at the jump target plus one (if forwards).
632 		 */
633 		linenum = adjsline(jump_sline);
634 		pos = position(linenum);
635 		if (search_type & SRCH_FORW)
636 		{
637 			pos = forw_raw_line(pos, (char **)NULL, (int *)NULL);
638 			while (pos == NULL_POSITION)
639 			{
640 				if (++linenum >= sc_height)
641 					break;
642 				pos = position(linenum);
643 			}
644 		} else
645 		{
646 			while (pos == NULL_POSITION)
647 			{
648 				if (--linenum < 0)
649 					break;
650 				pos = position(linenum);
651 			}
652 		}
653 	}
654 	return (pos);
655 }
656 
657 /*
658  * Search a subset of the file, specified by start/end position.
659  */
660 	static int
661 search_range(pos, endpos, search_type, matches, maxlines, plinepos, pendpos)
662 	POSITION pos;
663 	POSITION endpos;
664 	int search_type;
665 	int matches;
666 	int maxlines;
667 	POSITION *plinepos;
668 	POSITION *pendpos;
669 {
670 	char *line;
671 	char *cline;
672 	int line_len;
673 	LINENUM linenum;
674 	char *sp, *ep;
675 	int line_match;
676 	int cvt_ops;
677 	int cvt_len;
678 	int *chpos;
679 	POSITION linepos, oldpos;
680 
681 	linenum = find_linenum(pos);
682 	oldpos = pos;
683 	for (;;)
684 	{
685 		/*
686 		 * Get lines until we find a matching one or until
687 		 * we hit end-of-file (or beginning-of-file if we're
688 		 * going backwards), or until we hit the end position.
689 		 */
690 		if (ABORT_SIGS())
691 		{
692 			/*
693 			 * A signal aborts the search.
694 			 */
695 			return (-1);
696 		}
697 
698 		if ((endpos != NULL_POSITION && pos >= endpos) || maxlines == 0)
699 		{
700 			/*
701 			 * Reached end position without a match.
702 			 */
703 			if (pendpos != NULL)
704 				*pendpos = pos;
705 			return (matches);
706 		}
707 		if (maxlines > 0)
708 			maxlines--;
709 
710 		if (search_type & SRCH_FORW)
711 		{
712 			/*
713 			 * Read the next line, and save the
714 			 * starting position of that line in linepos.
715 			 */
716 			linepos = pos;
717 			pos = forw_raw_line(pos, &line, &line_len);
718 			if (linenum != 0)
719 				linenum++;
720 		} else
721 		{
722 			/*
723 			 * Read the previous line and save the
724 			 * starting position of that line in linepos.
725 			 */
726 			pos = back_raw_line(pos, &line, &line_len);
727 			linepos = pos;
728 			if (linenum != 0)
729 				linenum--;
730 		}
731 
732 		if (pos == NULL_POSITION)
733 		{
734 			/*
735 			 * Reached EOF/BOF without a match.
736 			 */
737 			if (pendpos != NULL)
738 				*pendpos = oldpos;
739 			return (matches);
740 		}
741 
742 		/*
743 		 * If we're using line numbers, we might as well
744 		 * remember the information we have now (the position
745 		 * and line number of the current line).
746 		 * Don't do it for every line because it slows down
747 		 * the search.  Remember the line number only if
748 		 * we're "far" from the last place we remembered it.
749 		 */
750 		if (linenums && abs((int)(pos - oldpos)) > 2048)
751 			add_lnum(linenum, pos);
752 		oldpos = pos;
753 
754 		if (is_filtered(linepos))
755 			continue;
756 
757 		/*
758 		 * If it's a caseless search, convert the line to lowercase.
759 		 * If we're doing backspace processing, delete backspaces.
760 		 */
761 		cvt_ops = get_cvt_ops();
762 		cvt_len = cvt_length(line_len, cvt_ops);
763 		cline = (char *) ecalloc(1, cvt_len);
764 		chpos = cvt_alloc_chpos(cvt_len);
765 		cvt_text(cline, line, chpos, &line_len, cvt_ops);
766 
767 #if HILITE_SEARCH
768 		/*
769 		 * Check to see if the line matches the filter pattern.
770 		 * If so, add an entry to the filter list.
771 		 */
772 		if ((search_type & SRCH_FIND_ALL) && prev_pattern(&filter_info)) {
773 			int line_filter = match_pattern(filter_info.compiled, filter_info.text,
774 				cline, line_len, &sp, &ep, 0, filter_info.search_type);
775 			if (line_filter)
776 			{
777 				struct hilite *hl = (struct hilite *)
778 					ecalloc(1, sizeof(struct hilite));
779 				hl->hl_startpos = linepos;
780 				hl->hl_endpos = pos;
781 				add_hilite(&filter_anchor, hl);
782 			}
783 		}
784 #endif
785 
786 		/*
787 		 * Test the next line to see if we have a match.
788 		 * We are successful if we either want a match and got one,
789 		 * or if we want a non-match and got one.
790 		 */
791 		if (prev_pattern(&search_info))
792 		{
793 			line_match = match_pattern(search_info.compiled, search_info.text,
794 				cline, line_len, &sp, &ep, 0, search_type); //FIXME search_info.search_type
795 			if (line_match)
796 			{
797 				/*
798 				 * Got a match.
799 				 */
800 				if (search_type & SRCH_FIND_ALL)
801 				{
802 #if HILITE_SEARCH
803 					/*
804 					 * We are supposed to find all matches in the range.
805 					 * Just add the matches in this line to the
806 					 * hilite list and keep searching.
807 					 */
808 					hilite_line(linepos, cline, line_len, chpos, sp, ep, cvt_ops);
809 #endif
810 				} else if (--matches <= 0)
811 				{
812 					/*
813 					 * Found the one match we're looking for.
814 					 * Return it.
815 					 */
816 #if HILITE_SEARCH
817 					if (hilite_search == OPT_ON)
818 					{
819 						/*
820 						 * Clear the hilite list and add only
821 						 * the matches in this one line.
822 						 */
823 						clr_hilite();
824 						hilite_line(linepos, cline, line_len, chpos, sp, ep, cvt_ops);
825 					}
826 #endif
827 					free(cline);
828 					free(chpos);
829 					if (plinepos != NULL)
830 						*plinepos = linepos;
831 					return (0);
832 				}
833 			}
834 		}
835 		free(cline);
836 		free(chpos);
837 	}
838 }
839 
840 /*
841  * search for a pattern in history. If found, compile that pattern.
842  */
843 	static int
844 hist_pattern(search_type)
845 	int search_type;
846 {
847 #if CMD_HISTORY
848 	char *pattern;
849 
850 	set_mlist(ml_search, 0);
851 	pattern = cmd_lastpattern();
852 	if (pattern == NULL)
853 		return (0);
854 
855 	if (set_pattern(&search_info, pattern, search_type) < 0)
856 		return (0);
857 
858 	is_ucase_pattern = is_ucase(pattern);
859 	if (is_ucase_pattern && caseless != OPT_ONPLUS)
860 		is_caseless = 0;
861 	else
862 		is_caseless = caseless;
863 
864 #if HILITE_SEARCH
865 	if (hilite_search == OPT_ONPLUS && !hide_hilite)
866 		hilite_screen();
867 #endif
868 
869 	return (1);
870 #else /* CMD_HISTORY */
871 	return (0);
872 #endif /* CMD_HISTORY */
873 }
874 
875 /*
876  * Search for the n-th occurrence of a specified pattern,
877  * either forward or backward.
878  * Return the number of matches not yet found in this file
879  * (that is, n minus the number of matches found).
880  * Return -1 if the search should be aborted.
881  * Caller may continue the search in another file
882  * if less than n matches are found in this file.
883  */
884 	public int
885 search(search_type, pattern, n)
886 	int search_type;
887 	char *pattern;
888 	int n;
889 {
890 	POSITION pos;
891 
892 	if (pattern == NULL || *pattern == '\0')
893 	{
894 		/*
895 		 * A null pattern means use the previously compiled pattern.
896 		 */
897 		if (!prev_pattern(&search_info) && !hist_pattern(search_type))
898 		{
899 			error("No previous regular expression", NULL_PARG);
900 			return (-1);
901 		}
902 		if ((search_type & SRCH_NO_REGEX) !=
903 		      (search_info.search_type & SRCH_NO_REGEX))
904 		{
905 			error("Please re-enter search pattern", NULL_PARG);
906 			return -1;
907 		}
908 #if HILITE_SEARCH
909 		if (hilite_search == OPT_ON)
910 		{
911 			/*
912 			 * Erase the highlights currently on screen.
913 			 * If the search fails, we'll redisplay them later.
914 			 */
915 			repaint_hilite(0);
916 		}
917 		if (hilite_search == OPT_ONPLUS && hide_hilite)
918 		{
919 			/*
920 			 * Highlight any matches currently on screen,
921 			 * before we actually start the search.
922 			 */
923 			hide_hilite = 0;
924 			hilite_screen();
925 		}
926 		hide_hilite = 0;
927 #endif
928 	} else
929 	{
930 		/*
931 		 * Compile the pattern.
932 		 */
933 		if (set_pattern(&search_info, pattern, search_type) < 0)
934 			return (-1);
935 		/*
936 		 * Ignore case if -I is set OR
937 		 * -i is set AND the pattern is all lowercase.
938 		 */
939 		is_ucase_pattern = is_ucase(pattern);
940 		if (is_ucase_pattern && caseless != OPT_ONPLUS)
941 			is_caseless = 0;
942 		else
943 			is_caseless = caseless;
944 #if HILITE_SEARCH
945 		if (hilite_search)
946 		{
947 			/*
948 			 * Erase the highlights currently on screen.
949 			 * Also permanently delete them from the hilite list.
950 			 */
951 			repaint_hilite(0);
952 			hide_hilite = 0;
953 			clr_hilite();
954 		}
955 		if (hilite_search == OPT_ONPLUS)
956 		{
957 			/*
958 			 * Highlight any matches currently on screen,
959 			 * before we actually start the search.
960 			 */
961 			hilite_screen();
962 		}
963 #endif
964 	}
965 
966 	/*
967 	 * Figure out where to start the search.
968 	 */
969 	pos = search_pos(search_type);
970 	if (pos == NULL_POSITION)
971 	{
972 		/*
973 		 * Can't find anyplace to start searching from.
974 		 */
975 		if (search_type & SRCH_PAST_EOF)
976 			return (n);
977 		/* repaint(); -- why was this here? */
978 		error("Nothing to search", NULL_PARG);
979 		return (-1);
980 	}
981 
982 	n = search_range(pos, NULL_POSITION, search_type, n, -1,
983 			&pos, (POSITION*)NULL);
984 	if (n != 0)
985 	{
986 		/*
987 		 * Search was unsuccessful.
988 		 */
989 #if HILITE_SEARCH
990 		if (hilite_search == OPT_ON && n > 0)
991 			/*
992 			 * Redisplay old hilites.
993 			 */
994 			repaint_hilite(1);
995 #endif
996 		return (n);
997 	}
998 
999 	if (!(search_type & SRCH_NO_MOVE))
1000 	{
1001 		/*
1002 		 * Go to the matching line.
1003 		 */
1004 		jump_loc(pos, jump_sline);
1005 	}
1006 
1007 #if HILITE_SEARCH
1008 	if (hilite_search == OPT_ON)
1009 		/*
1010 		 * Display new hilites in the matching line.
1011 		 */
1012 		repaint_hilite(1);
1013 #endif
1014 	return (0);
1015 }
1016 
1017 
1018 #if HILITE_SEARCH
1019 /*
1020  * Prepare hilites in a given range of the file.
1021  *
1022  * The pair (prep_startpos,prep_endpos) delimits a contiguous region
1023  * of the file that has been "prepared"; that is, scanned for matches for
1024  * the current search pattern, and hilites have been created for such matches.
1025  * If prep_startpos == NULL_POSITION, the prep region is empty.
1026  * If prep_endpos == NULL_POSITION, the prep region extends to EOF.
1027  * prep_hilite asks that the range (spos,epos) be covered by the prep region.
1028  */
1029 	public void
1030 prep_hilite(spos, epos, maxlines)
1031 	POSITION spos;
1032 	POSITION epos;
1033 	int maxlines;
1034 {
1035 	POSITION nprep_startpos = prep_startpos;
1036 	POSITION nprep_endpos = prep_endpos;
1037 	POSITION new_epos;
1038 	POSITION max_epos;
1039 	int result;
1040 	int i;
1041 
1042 /*
1043  * Search beyond where we're asked to search, so the prep region covers
1044  * more than we need.  Do one big search instead of a bunch of small ones.
1045  */
1046 #define	SEARCH_MORE (3*size_linebuf)
1047 
1048 	if (!prev_pattern(&search_info) && !is_filtering())
1049 		return;
1050 
1051 	/*
1052 	 * If we're limited to a max number of lines, figure out the
1053 	 * file position we should stop at.
1054 	 */
1055 	if (maxlines < 0)
1056 		max_epos = NULL_POSITION;
1057 	else
1058 	{
1059 		max_epos = spos;
1060 		for (i = 0;  i < maxlines;  i++)
1061 			max_epos = forw_raw_line(max_epos, (char **)NULL, (int *)NULL);
1062 	}
1063 
1064 	/*
1065 	 * Find two ranges:
1066 	 * The range that we need to search (spos,epos); and the range that
1067 	 * the "prep" region will then cover (nprep_startpos,nprep_endpos).
1068 	 */
1069 
1070 	if (prep_startpos == NULL_POSITION ||
1071 	    (epos != NULL_POSITION && epos < prep_startpos) ||
1072 	    spos > prep_endpos)
1073 	{
1074 		/*
1075 		 * New range is not contiguous with old prep region.
1076 		 * Discard the old prep region and start a new one.
1077 		 */
1078 		clr_hilite();
1079 		clr_filter();
1080 		if (epos != NULL_POSITION)
1081 			epos += SEARCH_MORE;
1082 		nprep_startpos = spos;
1083 	} else
1084 	{
1085 		/*
1086 		 * New range partially or completely overlaps old prep region.
1087 		 */
1088 		if (epos == NULL_POSITION)
1089 		{
1090 			/*
1091 			 * New range goes to end of file.
1092 			 */
1093 			;
1094 		} else if (epos > prep_endpos)
1095 		{
1096 			/*
1097 			 * New range ends after old prep region.
1098 			 * Extend prep region to end at end of new range.
1099 			 */
1100 			epos += SEARCH_MORE;
1101 		} else /* (epos <= prep_endpos) */
1102 		{
1103 			/*
1104 			 * New range ends within old prep region.
1105 			 * Truncate search to end at start of old prep region.
1106 			 */
1107 			epos = prep_startpos;
1108 		}
1109 
1110 		if (spos < prep_startpos)
1111 		{
1112 			/*
1113 			 * New range starts before old prep region.
1114 			 * Extend old prep region backwards to start at
1115 			 * start of new range.
1116 			 */
1117 			if (spos < SEARCH_MORE)
1118 				spos = 0;
1119 			else
1120 				spos -= SEARCH_MORE;
1121 			nprep_startpos = spos;
1122 		} else /* (spos >= prep_startpos) */
1123 		{
1124 			/*
1125 			 * New range starts within or after old prep region.
1126 			 * Trim search to start at end of old prep region.
1127 			 */
1128 			spos = prep_endpos;
1129 		}
1130 	}
1131 
1132 	if (epos != NULL_POSITION && max_epos != NULL_POSITION &&
1133 	    epos > max_epos)
1134 		/*
1135 		 * Don't go past the max position we're allowed.
1136 		 */
1137 		epos = max_epos;
1138 
1139 	if (epos == NULL_POSITION || epos > spos)
1140 	{
1141 		int search_type = SRCH_FORW | SRCH_FIND_ALL;
1142 		search_type |= (search_info.search_type & SRCH_NO_REGEX);
1143 		result = search_range(spos, epos, search_type, 0,
1144 				maxlines, (POSITION*)NULL, &new_epos);
1145 		if (result < 0)
1146 			return;
1147 		if (prep_endpos == NULL_POSITION || new_epos > prep_endpos)
1148 			nprep_endpos = new_epos;
1149 	}
1150 	prep_startpos = nprep_startpos;
1151 	prep_endpos = nprep_endpos;
1152 }
1153 
1154 /*
1155  * Set the pattern to be used for line filtering.
1156  */
1157 	public void
1158 set_filter_pattern(pattern, search_type)
1159 	char *pattern;
1160 	int search_type;
1161 {
1162 	clr_filter();
1163 	if (pattern == NULL || *pattern == '\0')
1164 		clear_pattern(&filter_info);
1165 	else
1166 		set_pattern(&filter_info, pattern, search_type);
1167 	screen_trashed = 1;
1168 }
1169 
1170 /*
1171  * Is there a line filter in effect?
1172  */
1173 	public int
1174 is_filtering()
1175 {
1176 	if (ch_getflags() & CH_HELPFILE)
1177 		return (0);
1178 	return prev_pattern(&filter_info);
1179 }
1180 #endif
1181 
1182 #if HAVE_V8_REGCOMP
1183 /*
1184  * This function is called by the V8 regcomp to report
1185  * errors in regular expressions.
1186  */
1187 	void
1188 regerror(s)
1189 	char *s;
1190 {
1191 	PARG parg;
1192 
1193 	parg.p_string = s;
1194 	error("%s", &parg);
1195 }
1196 #endif
1197 
1198