search.c 62.8 KB
Newer Older
Jim Blandy's avatar
Jim Blandy committed
1
/* String search routines for GNU Emacs.
Karl Heuer's avatar
Karl Heuer committed
2
   Copyright (C) 1985, 1986, 1987, 1993, 1994 Free Software Foundation, Inc.
Jim Blandy's avatar
Jim Blandy committed
3 4 5 6 7

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
Karl Heuer's avatar
Karl Heuer committed
8
the Free Software Foundation; either version 2, or (at your option)
Jim Blandy's avatar
Jim Blandy committed
9 10 11 12 13 14 15 16 17
any later version.

GNU Emacs 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
18 19
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */
Jim Blandy's avatar
Jim Blandy committed
20 21


22
#include <config.h>
Jim Blandy's avatar
Jim Blandy committed
23 24 25
#include "lisp.h"
#include "syntax.h"
#include "buffer.h"
26
#include "region-cache.h"
Jim Blandy's avatar
Jim Blandy committed
27
#include "commands.h"
28
#include "blockinput.h"
Jim Blandy's avatar
Jim Blandy committed
29

Jim Blandy's avatar
Jim Blandy committed
30 31 32
#include <sys/types.h>
#include "regex.h"

33
#define REGEXP_CACHE_SIZE 20
Jim Blandy's avatar
Jim Blandy committed
34

35 36
/* If the regexp is non-nil, then the buffer contains the compiled form
   of that regexp, suitable for searching.  */
37 38
struct regexp_cache
{
39 40 41 42
  struct regexp_cache *next;
  Lisp_Object regexp;
  struct re_pattern_buffer buf;
  char fastmap[0400];
43 44
  /* Nonzero means regexp was compiled to do full POSIX backtracking.  */
  char posix;
45
};
Jim Blandy's avatar
Jim Blandy committed
46

47 48
/* The instances of that struct.  */
struct regexp_cache searchbufs[REGEXP_CACHE_SIZE];
Jim Blandy's avatar
Jim Blandy committed
49

50 51
/* The head of the linked list; points to the most recently used buffer.  */
struct regexp_cache *searchbuf_head;
Jim Blandy's avatar
Jim Blandy committed
52 53


Jim Blandy's avatar
Jim Blandy committed
54 55 56 57 58 59 60
/* Every call to re_match, etc., must pass &search_regs as the regs
   argument unless you can show it is unnecessary (i.e., if re_match
   is certainly going to be called again before region-around-match
   can be called).

   Since the registers are now dynamically allocated, we need to make
   sure not to refer to the Nth register before checking that it has
Jim Blandy's avatar
Jim Blandy committed
61 62 63
   been allocated by checking search_regs.num_regs.

   The regex code keeps track of whether it has allocated the search
64 65
   buffer using bits in the re_pattern_buffer.  This means that whenever
   you compile a new pattern, it completely forgets whether it has
Jim Blandy's avatar
Jim Blandy committed
66 67 68 69 70
   allocated any registers, and will allocate new registers the next
   time you call a searching or matching function.  Therefore, we need
   to call re_set_registers after compiling a new pattern or after
   setting the match registers, so that the regex functions will be
   able to free or re-allocate it properly.  */
Jim Blandy's avatar
Jim Blandy committed
71 72
static struct re_registers search_regs;

Jim Blandy's avatar
Jim Blandy committed
73 74 75 76
/* The buffer in which the last search was performed, or
   Qt if the last search was done in a string;
   Qnil if no searching has been done yet.  */
static Lisp_Object last_thing_searched;
Jim Blandy's avatar
Jim Blandy committed
77

Karl Heuer's avatar
Karl Heuer committed
78
/* error condition signaled when regexp compile_pattern fails */
Jim Blandy's avatar
Jim Blandy committed
79 80 81

Lisp_Object Qinvalid_regexp;

82
static void set_search_regs ();
83
static void save_search_regs ();
84

85 86
static int search_buffer ();

Jim Blandy's avatar
Jim Blandy committed
87 88 89 90 91 92 93 94 95 96 97 98
static void
matcher_overflow ()
{
  error ("Stack overflow in regexp matcher");
}

#ifdef __STDC__
#define CONST const
#else
#define CONST
#endif

99 100 101 102 103 104 105 106 107 108
/* Compile a regexp and signal a Lisp error if anything goes wrong.
   PATTERN is the pattern to compile.
   CP is the place to put the result.
   TRANSLATE is a translation table for ignoring case, or NULL for none.
   REGP is the structure that says where to store the "register"
   values that will result from matching this pattern.
   If it is 0, we should compile the pattern not to record any
   subexpression bounds.
   POSIX is nonzero if we want full backtracking (POSIX style)
   for this pattern.  0 means backtrack only enough to get a valid match.  */
Jim Blandy's avatar
Jim Blandy committed
109

110
static void
111
compile_pattern_1 (cp, pattern, translate, regp, posix)
112
     struct regexp_cache *cp;
Jim Blandy's avatar
Jim Blandy committed
113
     Lisp_Object pattern;
114
     Lisp_Object *translate;
115
     struct re_registers *regp;
116
     int posix;
Jim Blandy's avatar
Jim Blandy committed
117 118
{
  CONST char *val;
119
  reg_syntax_t old;
Jim Blandy's avatar
Jim Blandy committed
120

121 122
  cp->regexp = Qnil;
  cp->buf.translate = translate;
123
  cp->posix = posix;
124
  BLOCK_INPUT;
125 126
  old = re_set_syntax (RE_SYNTAX_EMACS
		       | (posix ? 0 : RE_NO_POSIX_BACKTRACKING));
127
  val = (CONST char *) re_compile_pattern ((char *) XSTRING (pattern)->data,
128
					   XSTRING (pattern)->size, &cp->buf);
129
  re_set_syntax (old);
130
  UNBLOCK_INPUT;
Jim Blandy's avatar
Jim Blandy committed
131
  if (val)
132
    Fsignal (Qinvalid_regexp, Fcons (build_string (val), Qnil));
Jim Blandy's avatar
Jim Blandy committed
133

134 135 136 137
  cp->regexp = Fcopy_sequence (pattern);
}

/* Compile a regexp if necessary, but first check to see if there's one in
138 139 140 141 142 143 144 145 146
   the cache.
   PATTERN is the pattern to compile.
   TRANSLATE is a translation table for ignoring case, or NULL for none.
   REGP is the structure that says where to store the "register"
   values that will result from matching this pattern.
   If it is 0, we should compile the pattern not to record any
   subexpression bounds.
   POSIX is nonzero if we want full backtracking (POSIX style)
   for this pattern.  0 means backtrack only enough to get a valid match.  */
147 148

struct re_pattern_buffer *
149
compile_pattern (pattern, regp, translate, posix)
150 151
     Lisp_Object pattern;
     struct re_registers *regp;
152
     Lisp_Object *translate;
153
     int posix;
154 155 156 157 158 159
{
  struct regexp_cache *cp, **cpp;

  for (cpp = &searchbuf_head; ; cpp = &cp->next)
    {
      cp = *cpp;
160 161
      if (XSTRING (cp->regexp)->size == XSTRING (pattern)->size
	  && !NILP (Fstring_equal (cp->regexp, pattern))
162 163
	  && cp->buf.translate == translate
	  && cp->posix == posix)
164 165 166 167 168
	break;

      /* If we're at the end of the cache, compile into the last cell.  */
      if (cp->next == 0)
	{
169
	  compile_pattern_1 (cp, pattern, translate, regp, posix);
170 171 172 173 174 175 176 177 178 179
	  break;
	}
    }

  /* When we get here, cp (aka *cpp) contains the compiled pattern,
     either because we found it in the cache or because we just compiled it.
     Move it to the front of the queue to mark it as most recently used.  */
  *cpp = cp->next;
  cp->next = searchbuf_head;
  searchbuf_head = cp;
Jim Blandy's avatar
Jim Blandy committed
180

181 182 183 184 185
  /* Advise the searching functions about the space we have allocated
     for register data.  */
  if (regp)
    re_set_registers (&cp->buf, regp, regp->num_regs, regp->start, regp->end);

186
  return &cp->buf;
Jim Blandy's avatar
Jim Blandy committed
187 188 189 190 191 192 193 194 195 196 197 198 199
}

/* Error condition used for failing searches */
Lisp_Object Qsearch_failed;

Lisp_Object
signal_failure (arg)
     Lisp_Object arg;
{
  Fsignal (Qsearch_failed, Fcons (arg, Qnil));
  return Qnil;
}

200 201
static Lisp_Object
looking_at_1 (string, posix)
Jim Blandy's avatar
Jim Blandy committed
202
     Lisp_Object string;
203
     int posix;
Jim Blandy's avatar
Jim Blandy committed
204 205 206 207 208
{
  Lisp_Object val;
  unsigned char *p1, *p2;
  int s1, s2;
  register int i;
209
  struct re_pattern_buffer *bufp;
Jim Blandy's avatar
Jim Blandy committed
210

211 212 213
  if (running_asynch_code)
    save_search_regs ();

Jim Blandy's avatar
Jim Blandy committed
214
  CHECK_STRING (string, 0);
215 216
  bufp = compile_pattern (string, &search_regs,
			  (!NILP (current_buffer->case_fold_search)
217 218
			   ? DOWNCASE_TABLE : 0),
			  posix);
Jim Blandy's avatar
Jim Blandy committed
219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241

  immediate_quit = 1;
  QUIT;			/* Do a pending quit right away, to avoid paradoxical behavior */

  /* Get pointers and sizes of the two strings
     that make up the visible portion of the buffer. */

  p1 = BEGV_ADDR;
  s1 = GPT - BEGV;
  p2 = GAP_END_ADDR;
  s2 = ZV - GPT;
  if (s1 < 0)
    {
      p2 = p1;
      s2 = ZV - BEGV;
      s1 = 0;
    }
  if (s2 < 0)
    {
      s1 = ZV - BEGV;
      s2 = 0;
    }
  
242
  i = re_match_2 (bufp, (char *) p1, s1, (char *) p2, s2,
243
		  PT - BEGV, &search_regs,
Jim Blandy's avatar
Jim Blandy committed
244 245 246 247 248
		  ZV - BEGV);
  if (i == -2)
    matcher_overflow ();

  val = (0 <= i ? Qt : Qnil);
Jim Blandy's avatar
Jim Blandy committed
249
  for (i = 0; i < search_regs.num_regs; i++)
Jim Blandy's avatar
Jim Blandy committed
250 251 252 253 254
    if (search_regs.start[i] >= 0)
      {
	search_regs.start[i] += BEGV;
	search_regs.end[i] += BEGV;
      }
255
  XSETBUFFER (last_thing_searched, current_buffer);
Jim Blandy's avatar
Jim Blandy committed
256 257 258 259
  immediate_quit = 0;
  return val;
}

260
DEFUN ("looking-at", Flooking_at, Slooking_at, 1, 1, 0,
261
  "Return t if text after point matches regular expression REGEXP.\n\
262 263 264
This function modifies the match data that `match-beginning',\n\
`match-end' and `match-data' access; save and restore the match\n\
data if you want to preserve them.")
265 266
  (regexp)
     Lisp_Object regexp;
267
{
268
  return looking_at_1 (regexp, 0);
269 270 271
}

DEFUN ("posix-looking-at", Fposix_looking_at, Sposix_looking_at, 1, 1, 0,
272
  "Return t if text after point matches regular expression REGEXP.\n\
273 274 275 276
Find the longest match, in accord with Posix regular expression rules.\n\
This function modifies the match data that `match-beginning',\n\
`match-end' and `match-data' access; save and restore the match\n\
data if you want to preserve them.")
277 278
  (regexp)
     Lisp_Object regexp;
279
{
280
  return looking_at_1 (regexp, 1);
281 282 283 284
}

static Lisp_Object
string_match_1 (regexp, string, start, posix)
Jim Blandy's avatar
Jim Blandy committed
285
     Lisp_Object regexp, string, start;
286
     int posix;
Jim Blandy's avatar
Jim Blandy committed
287 288 289
{
  int val;
  int s;
290
  struct re_pattern_buffer *bufp;
Jim Blandy's avatar
Jim Blandy committed
291

292 293 294
  if (running_asynch_code)
    save_search_regs ();

Jim Blandy's avatar
Jim Blandy committed
295 296 297 298 299 300 301 302 303 304 305 306
  CHECK_STRING (regexp, 0);
  CHECK_STRING (string, 1);

  if (NILP (start))
    s = 0;
  else
    {
      int len = XSTRING (string)->size;

      CHECK_NUMBER (start, 2);
      s = XINT (start);
      if (s < 0 && -s <= len)
Karl Heuer's avatar
Karl Heuer committed
307
	s = len + s;
Jim Blandy's avatar
Jim Blandy committed
308 309 310 311
      else if (0 > s || s > len)
	args_out_of_range (string, start);
    }

312 313
  bufp = compile_pattern (regexp, &search_regs,
			  (!NILP (current_buffer->case_fold_search)
314
			   ? DOWNCASE_TABLE : 0),
315
			  posix);
Jim Blandy's avatar
Jim Blandy committed
316
  immediate_quit = 1;
317
  val = re_search (bufp, (char *) XSTRING (string)->data,
Jim Blandy's avatar
Jim Blandy committed
318 319 320
		   XSTRING (string)->size, s, XSTRING (string)->size - s,
		   &search_regs);
  immediate_quit = 0;
Jim Blandy's avatar
Jim Blandy committed
321
  last_thing_searched = Qt;
Jim Blandy's avatar
Jim Blandy committed
322 323 324 325 326
  if (val == -2)
    matcher_overflow ();
  if (val < 0) return Qnil;
  return make_number (val);
}
Richard M. Stallman's avatar
Richard M. Stallman committed
327

328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352
DEFUN ("string-match", Fstring_match, Sstring_match, 2, 3, 0,
  "Return index of start of first match for REGEXP in STRING, or nil.\n\
If third arg START is non-nil, start search at that index in STRING.\n\
For index of first char beyond the match, do (match-end 0).\n\
`match-end' and `match-beginning' also give indices of substrings\n\
matched by parenthesis constructs in the pattern.")
  (regexp, string, start)
     Lisp_Object regexp, string, start;
{
  return string_match_1 (regexp, string, start, 0);
}

DEFUN ("posix-string-match", Fposix_string_match, Sposix_string_match, 2, 3, 0,
  "Return index of start of first match for REGEXP in STRING, or nil.\n\
Find the longest match, in accord with Posix regular expression rules.\n\
If third arg START is non-nil, start search at that index in STRING.\n\
For index of first char beyond the match, do (match-end 0).\n\
`match-end' and `match-beginning' also give indices of substrings\n\
matched by parenthesis constructs in the pattern.")
  (regexp, string, start)
     Lisp_Object regexp, string, start;
{
  return string_match_1 (regexp, string, start, 1);
}

Richard M. Stallman's avatar
Richard M. Stallman committed
353 354 355 356 357 358 359 360 361
/* Match REGEXP against STRING, searching all of STRING,
   and return the index of the match, or negative on failure.
   This does not clobber the match data.  */

int
fast_string_match (regexp, string)
     Lisp_Object regexp, string;
{
  int val;
362
  struct re_pattern_buffer *bufp;
Richard M. Stallman's avatar
Richard M. Stallman committed
363

364
  bufp = compile_pattern (regexp, 0, 0, 0);
Richard M. Stallman's avatar
Richard M. Stallman committed
365
  immediate_quit = 1;
366
  val = re_search (bufp, (char *) XSTRING (string)->data,
Richard M. Stallman's avatar
Richard M. Stallman committed
367 368 369 370 371
		   XSTRING (string)->size, 0, XSTRING (string)->size,
		   0);
  immediate_quit = 0;
  return val;
}
Jim Blandy's avatar
Jim Blandy committed
372

373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426
/* max and min.  */

static int
max (a, b)
     int a, b;
{
  return ((a > b) ? a : b);
}

static int
min (a, b)
     int a, b;
{
  return ((a < b) ? a : b);
}


/* The newline cache: remembering which sections of text have no newlines.  */

/* If the user has requested newline caching, make sure it's on.
   Otherwise, make sure it's off.
   This is our cheezy way of associating an action with the change of
   state of a buffer-local variable.  */
static void
newline_cache_on_off (buf)
     struct buffer *buf;
{
  if (NILP (buf->cache_long_line_scans))
    {
      /* It should be off.  */
      if (buf->newline_cache)
        {
          free_region_cache (buf->newline_cache);
          buf->newline_cache = 0;
        }
    }
  else
    {
      /* It should be on.  */
      if (buf->newline_cache == 0)
        buf->newline_cache = new_region_cache ();
    }
}


/* Search for COUNT instances of the character TARGET between START and END.

   If COUNT is positive, search forwards; END must be >= START.
   If COUNT is negative, search backwards for the -COUNTth instance;
      END must be <= START.
   If COUNT is zero, do anything you please; run rogue, for all I care.

   If END is zero, use BEGV or ZV instead, as appropriate for the
   direction indicated by COUNT.
Jim Blandy's avatar
Jim Blandy committed
427 428

   If we find COUNT instances, set *SHORTAGE to zero, and return the
Richard M. Stallman's avatar
Richard M. Stallman committed
429 430
   position after the COUNTth match.  Note that for reverse motion
   this is not the same as the usual convention for Emacs motion commands.
Jim Blandy's avatar
Jim Blandy committed
431

432 433
   If we don't find COUNT instances before reaching END, set *SHORTAGE
   to the number of TARGETs left unfound, and return END.
Jim Blandy's avatar
Jim Blandy committed
434

435 436 437
   If ALLOW_QUIT is non-zero, set immediate_quit.  That's good to do
   except when inside redisplay.  */

438 439 440 441 442
scan_buffer (target, start, end, count, shortage, allow_quit)
     register int target;
     int start, end;
     int count;
     int *shortage;
443
     int allow_quit;
Jim Blandy's avatar
Jim Blandy committed
444
{
445 446
  struct region_cache *newline_cache;
  int direction; 
Jim Blandy's avatar
Jim Blandy committed
447

448 449 450 451 452 453 454 455 456 457
  if (count > 0)
    {
      direction = 1;
      if (! end) end = ZV;
    }
  else
    {
      direction = -1;
      if (! end) end = BEGV;
    }
Jim Blandy's avatar
Jim Blandy committed
458

459 460
  newline_cache_on_off (current_buffer);
  newline_cache = current_buffer->newline_cache;
Jim Blandy's avatar
Jim Blandy committed
461 462 463 464

  if (shortage != 0)
    *shortage = 0;

465
  immediate_quit = allow_quit;
Jim Blandy's avatar
Jim Blandy committed
466

Jim Blandy's avatar
Jim Blandy committed
467
  if (count > 0)
468
    while (start != end)
Jim Blandy's avatar
Jim Blandy committed
469
      {
470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485
        /* Our innermost scanning loop is very simple; it doesn't know
           about gaps, buffer ends, or the newline cache.  ceiling is
           the position of the last character before the next such
           obstacle --- the last character the dumb search loop should
           examine.  */
        register int ceiling = end - 1;

        /* If we're looking for a newline, consult the newline cache
           to see where we can avoid some scanning.  */
        if (target == '\n' && newline_cache)
          {
            int next_change;
            immediate_quit = 0;
            while (region_cache_forward
                   (current_buffer, newline_cache, start, &next_change))
              start = next_change;
486
            immediate_quit = allow_quit;
487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537

            /* start should never be after end.  */
            if (start >= end)
              start = end - 1;

            /* Now the text after start is an unknown region, and
               next_change is the position of the next known region. */
            ceiling = min (next_change - 1, ceiling);
          }

        /* The dumb loop can only scan text stored in contiguous
           bytes. BUFFER_CEILING_OF returns the last character
           position that is contiguous, so the ceiling is the
           position after that.  */
        ceiling = min (BUFFER_CEILING_OF (start), ceiling);

        {
          /* The termination address of the dumb loop.  */ 
          register unsigned char *ceiling_addr = &FETCH_CHAR (ceiling) + 1;
          register unsigned char *cursor = &FETCH_CHAR (start);
          unsigned char *base = cursor;

          while (cursor < ceiling_addr)
            {
              unsigned char *scan_start = cursor;

              /* The dumb loop.  */
              while (*cursor != target && ++cursor < ceiling_addr)
                ;

              /* If we're looking for newlines, cache the fact that
                 the region from start to cursor is free of them. */
              if (target == '\n' && newline_cache)
                know_region_cache (current_buffer, newline_cache,
                                   start + scan_start - base,
                                   start + cursor - base);

              /* Did we find the target character?  */
              if (cursor < ceiling_addr)
                {
                  if (--count == 0)
                    {
                      immediate_quit = 0;
                      return (start + cursor - base + 1);
                    }
                  cursor++;
                }
            }

          start += cursor - base;
        }
Jim Blandy's avatar
Jim Blandy committed
538 539
      }
  else
540 541 542 543 544 545 546 547 548 549 550 551 552
    while (start > end)
      {
        /* The last character to check before the next obstacle.  */
        register int ceiling = end;

        /* Consult the newline cache, if appropriate.  */
        if (target == '\n' && newline_cache)
          {
            int next_change;
            immediate_quit = 0;
            while (region_cache_backward
                   (current_buffer, newline_cache, start, &next_change))
              start = next_change;
553
            immediate_quit = allow_quit;
554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602

            /* Start should never be at or before end.  */
            if (start <= end)
              start = end + 1;

            /* Now the text before start is an unknown region, and
               next_change is the position of the next known region. */
            ceiling = max (next_change, ceiling);
          }

        /* Stop scanning before the gap.  */
        ceiling = max (BUFFER_FLOOR_OF (start - 1), ceiling);

        {
          /* The termination address of the dumb loop.  */
          register unsigned char *ceiling_addr = &FETCH_CHAR (ceiling);
          register unsigned char *cursor = &FETCH_CHAR (start - 1);
          unsigned char *base = cursor;

          while (cursor >= ceiling_addr)
            {
              unsigned char *scan_start = cursor;

              while (*cursor != target && --cursor >= ceiling_addr)
                ;

              /* If we're looking for newlines, cache the fact that
                 the region from after the cursor to start is free of them.  */
              if (target == '\n' && newline_cache)
                know_region_cache (current_buffer, newline_cache,
                                   start + cursor - base,
                                   start + scan_start - base);

              /* Did we find the target character?  */
              if (cursor >= ceiling_addr)
                {
                  if (++count >= 0)
                    {
                      immediate_quit = 0;
                      return (start + cursor - base);
                    }
                  cursor--;
                }
            }

          start += cursor - base;
        }
      }

Jim Blandy's avatar
Jim Blandy committed
603 604
  immediate_quit = 0;
  if (shortage != 0)
Jim Blandy's avatar
Jim Blandy committed
605
    *shortage = count * direction;
606
  return start;
Jim Blandy's avatar
Jim Blandy committed
607 608
}

609 610 611 612
int
find_next_newline_no_quit (from, cnt)
     register int from, cnt;
{
613
  return scan_buffer ('\n', from, 0, cnt, (int *) 0, 0);
614 615
}

Jim Blandy's avatar
Jim Blandy committed
616 617 618 619
int
find_next_newline (from, cnt)
     register int from, cnt;
{
620 621 622 623 624 625 626 627 628
  return scan_buffer ('\n', from, 0, cnt, (int *) 0, 1);
}


/* Like find_next_newline, but returns position before the newline,
   not after, and only search up to TO.  This isn't just
   find_next_newline (...)-1, because you might hit TO.  */
int
find_before_next_newline (from, to, cnt)
629
     int from, to, cnt;
630 631 632 633 634 635 636 637
{
  int shortage;
  int pos = scan_buffer ('\n', from, to, cnt, &shortage, 1);

  if (shortage == 0)
    pos--;
  
  return pos;
Jim Blandy's avatar
Jim Blandy committed
638 639
}

640 641
Lisp_Object skip_chars ();

Jim Blandy's avatar
Jim Blandy committed
642
DEFUN ("skip-chars-forward", Fskip_chars_forward, Sskip_chars_forward, 1, 2, 0,
643 644
  "Move point forward, stopping before a char not in STRING, or at pos LIM.\n\
STRING is like the inside of a `[...]' in a regular expression\n\
Jim Blandy's avatar
Jim Blandy committed
645 646
except that `]' is never special and `\\' quotes `^', `-' or `\\'.\n\
Thus, with arg \"a-zA-Z\", this skips letters stopping before first nonletter.\n\
647 648
With arg \"^a-zA-Z\", skips nonletters stopping before first letter.\n\
Returns the distance traveled, either zero or positive.")
Jim Blandy's avatar
Jim Blandy committed
649 650 651
  (string, lim)
     Lisp_Object string, lim;
{
652
  return skip_chars (1, 0, string, lim);
Jim Blandy's avatar
Jim Blandy committed
653 654 655
}

DEFUN ("skip-chars-backward", Fskip_chars_backward, Sskip_chars_backward, 1, 2, 0,
656
  "Move point backward, stopping after a char not in STRING, or at pos LIM.\n\
657 658
See `skip-chars-forward' for details.\n\
Returns the distance traveled, either zero or negative.")
Jim Blandy's avatar
Jim Blandy committed
659 660 661
  (string, lim)
     Lisp_Object string, lim;
{
662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686
  return skip_chars (0, 0, string, lim);
}

DEFUN ("skip-syntax-forward", Fskip_syntax_forward, Sskip_syntax_forward, 1, 2, 0,
  "Move point forward across chars in specified syntax classes.\n\
SYNTAX is a string of syntax code characters.\n\
Stop before a char whose syntax is not in SYNTAX, or at position LIM.\n\
If SYNTAX starts with ^, skip characters whose syntax is NOT in SYNTAX.\n\
This function returns the distance traveled, either zero or positive.")
  (syntax, lim)
     Lisp_Object syntax, lim;
{
  return skip_chars (1, 1, syntax, lim);
}

DEFUN ("skip-syntax-backward", Fskip_syntax_backward, Sskip_syntax_backward, 1, 2, 0,
  "Move point backward across chars in specified syntax classes.\n\
SYNTAX is a string of syntax code characters.\n\
Stop on reaching a char whose syntax is not in SYNTAX, or at position LIM.\n\
If SYNTAX starts with ^, skip characters whose syntax is NOT in SYNTAX.\n\
This function returns the distance traveled, either zero or negative.")
  (syntax, lim)
     Lisp_Object syntax, lim;
{
  return skip_chars (0, 1, syntax, lim);
Jim Blandy's avatar
Jim Blandy committed
687 688
}

689
Lisp_Object
690 691
skip_chars (forwardp, syntaxp, string, lim)
     int forwardp, syntaxp;
Jim Blandy's avatar
Jim Blandy committed
692 693 694 695 696 697 698 699 700 701 702
     Lisp_Object string, lim;
{
  register unsigned char *p, *pend;
  register unsigned char c;
  unsigned char fastmap[0400];
  int negate = 0;
  register int i;

  CHECK_STRING (string, 0);

  if (NILP (lim))
703
    XSETINT (lim, forwardp ? ZV : BEGV);
Jim Blandy's avatar
Jim Blandy committed
704 705 706 707
  else
    CHECK_NUMBER_COERCE_MARKER (lim, 1);

  /* In any case, don't allow scan outside bounds of buffer.  */
708 709 710 711
  /* jla turned this off, for no known reason.
     bfox turned the ZV part on, and rms turned the
     BEGV part back on.  */
  if (XINT (lim) > ZV)
712
    XSETFASTINT (lim, ZV);
713
  if (XINT (lim) < BEGV)
714
    XSETFASTINT (lim, BEGV);
Jim Blandy's avatar
Jim Blandy committed
715 716 717 718 719 720 721 722 723 724

  p = XSTRING (string)->data;
  pend = p + XSTRING (string)->size;
  bzero (fastmap, sizeof fastmap);

  if (p != pend && *p == '^')
    {
      negate = 1; p++;
    }

725 726 727
  /* Find the characters specified and set their elements of fastmap.
     If syntaxp, each character counts as itself.
     Otherwise, handle backslashes and ranges specially  */
Jim Blandy's avatar
Jim Blandy committed
728 729 730 731

  while (p != pend)
    {
      c = *p++;
732 733 734
      if (syntaxp)
	fastmap[c] = 1;
      else
Jim Blandy's avatar
Jim Blandy committed
735
	{
736
	  if (c == '\\')
Jim Blandy's avatar
Jim Blandy committed
737
	    {
738 739 740 741 742 743 744 745 746 747 748 749 750
	      if (p == pend) break;
	      c = *p++;
	    }
	  if (p != pend && *p == '-')
	    {
	      p++;
	      if (p == pend) break;
	      while (c <= *p)
		{
		  fastmap[c] = 1;
		  c++;
		}
	      p++;
Jim Blandy's avatar
Jim Blandy committed
751
	    }
752 753
	  else
	    fastmap[c] = 1;
Jim Blandy's avatar
Jim Blandy committed
754 755 756
	}
    }

757 758 759
  if (syntaxp && fastmap['-'] != 0)
    fastmap[' '] = 1;

Jim Blandy's avatar
Jim Blandy committed
760 761 762 763 764 765
  /* If ^ was the first character, complement the fastmap. */

  if (negate)
    for (i = 0; i < sizeof fastmap; i++)
      fastmap[i] ^= 1;

766
  {
767
    int start_point = PT;
768 769

    immediate_quit = 1;
770
    if (syntaxp)
771
      {
772 773 774

	if (forwardp)
	  {
775 776 777
	    while (PT < XINT (lim)
		   && fastmap[(unsigned char) syntax_code_spec[(int) SYNTAX (FETCH_CHAR (PT))]])
	      SET_PT (PT + 1);
778 779 780
	  }
	else
	  {
781 782 783
	    while (PT > XINT (lim)
		   && fastmap[(unsigned char) syntax_code_spec[(int) SYNTAX (FETCH_CHAR (PT - 1))]])
	      SET_PT (PT - 1);
784
	  }
785 786 787
      }
    else
      {
788 789
	if (forwardp)
	  {
790 791
	    while (PT < XINT (lim) && fastmap[FETCH_CHAR (PT)])
	      SET_PT (PT + 1);
792 793 794
	  }
	else
	  {
795 796
	    while (PT > XINT (lim) && fastmap[FETCH_CHAR (PT - 1)])
	      SET_PT (PT - 1);
797
	  }
798 799 800
      }
    immediate_quit = 0;

801
    return make_number (PT - start_point);
802
  }
Jim Blandy's avatar
Jim Blandy committed
803 804 805 806 807
}

/* Subroutines of Lisp buffer search functions. */

static Lisp_Object
808
search_command (string, bound, noerror, count, direction, RE, posix)
Jim Blandy's avatar
Jim Blandy committed
809 810 811
     Lisp_Object string, bound, noerror, count;
     int direction;
     int RE;
812
     int posix;
Jim Blandy's avatar
Jim Blandy committed
813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830
{
  register int np;
  int lim;
  int n = direction;

  if (!NILP (count))
    {
      CHECK_NUMBER (count, 3);
      n *= XINT (count);
    }

  CHECK_STRING (string, 0);
  if (NILP (bound))
    lim = n > 0 ? ZV : BEGV;
  else
    {
      CHECK_NUMBER_COERCE_MARKER (bound, 1);
      lim = XINT (bound);
831
      if (n > 0 ? lim < PT : lim > PT)
Jim Blandy's avatar
Jim Blandy committed
832 833 834 835 836 837 838
	error ("Invalid search bound (wrong side of point)");
      if (lim > ZV)
	lim = ZV;
      if (lim < BEGV)
	lim = BEGV;
    }

839
  np = search_buffer (string, PT, lim, n, RE,
Jim Blandy's avatar
Jim Blandy committed
840
		      (!NILP (current_buffer->case_fold_search)
841 842
		       ? XCHAR_TABLE (current_buffer->case_canon_table)->contents
		       : 0),
Jim Blandy's avatar
Jim Blandy committed
843
		      (!NILP (current_buffer->case_fold_search)
844 845
		       ? XCHAR_TABLE (current_buffer->case_eqv_table)->contents
		       : 0),
846
		      posix);
Jim Blandy's avatar
Jim Blandy committed
847 848 849 850 851 852 853 854
  if (np <= 0)
    {
      if (NILP (noerror))
	return signal_failure (string);
      if (!EQ (noerror, Qt))
	{
	  if (lim < BEGV || lim > ZV)
	    abort ();
855 856 857 858
	  SET_PT (lim);
	  return Qnil;
#if 0 /* This would be clean, but maybe programs depend on
	 a value of nil here.  */
859
	  np = lim;
860
#endif
Jim Blandy's avatar
Jim Blandy committed
861
	}
862 863
      else
	return Qnil;
Jim Blandy's avatar
Jim Blandy committed
864 865 866 867 868 869 870 871 872 873
    }

  if (np < BEGV || np > ZV)
    abort ();

  SET_PT (np);

  return make_number (np);
}

Karl Heuer's avatar
Karl Heuer committed
874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893
static int
trivial_regexp_p (regexp)
     Lisp_Object regexp;
{
  int len = XSTRING (regexp)->size;
  unsigned char *s = XSTRING (regexp)->data;
  unsigned char c;
  while (--len >= 0)
    {
      switch (*s++)
	{
	case '.': case '*': case '+': case '?': case '[': case '^': case '$':
	  return 0;
	case '\\':
	  if (--len < 0)
	    return 0;
	  switch (*s++)
	    {
	    case '|': case '(': case ')': case '`': case '\'': case 'b':
	    case 'B': case '<': case '>': case 'w': case 'W': case 's':
894 895
	    case 'S': case '=':
	    case '1': case '2': case '3': case '4': case '5':
Karl Heuer's avatar
Karl Heuer committed
896 897 898 899 900 901 902 903
	    case '6': case '7': case '8': case '9':
	      return 0;
	    }
	}
    }
  return 1;
}

904
/* Search for the n'th occurrence of STRING in the current buffer,
Jim Blandy's avatar
Jim Blandy committed
905
   starting at position POS and stopping at position LIM,
906
   treating STRING as a literal string if RE is false or as
Jim Blandy's avatar
Jim Blandy committed
907 908 909 910 911 912 913
   a regular expression if RE is true.

   If N is positive, searching is forward and LIM must be greater than POS.
   If N is negative, searching is backward and LIM must be less than POS.

   Returns -x if only N-x occurrences found (x > 0),
   or else the position at the beginning of the Nth occurrence
914 915 916 917
   (if searching backward) or the end (if searching forward).

   POSIX is nonzero if we want full backtracking (POSIX style)
   for this pattern.  0 means backtrack only enough to get a valid match.  */
Jim Blandy's avatar
Jim Blandy committed
918

919 920
static int
search_buffer (string, pos, lim, n, RE, trt, inverse_trt, posix)
Jim Blandy's avatar
Jim Blandy committed
921 922 923 924 925
     Lisp_Object string;
     int pos;
     int lim;
     int n;
     int RE;
926 927
     Lisp_Object *trt;
     Lisp_Object *inverse_trt;
928
     int posix;
Jim Blandy's avatar
Jim Blandy committed
929 930 931 932 933 934 935 936 937 938 939 940 941
{
  int len = XSTRING (string)->size;
  unsigned char *base_pat = XSTRING (string)->data;
  register int *BM_tab;
  int *BM_tab_base;
  register int direction = ((n > 0) ? 1 : -1);
  register int dirlen;
  int infinity, limit, k, stride_for_teases;
  register unsigned char *pat, *cursor, *p_limit;  
  register int i, j;
  unsigned char *p1, *p2;
  int s1, s2;

942 943 944
  if (running_asynch_code)
    save_search_regs ();

Jim Blandy's avatar
Jim Blandy committed
945
  /* Null string is found at starting position.  */
946
  if (len == 0)
947 948 949 950
    {
      set_search_regs (pos, 0);
      return pos;
    }
951 952 953

  /* Searching 0 times means don't move.  */
  if (n == 0)
Jim Blandy's avatar
Jim Blandy committed
954 955
    return pos;

Karl Heuer's avatar
Karl Heuer committed
956
  if (RE && !trivial_regexp_p (string))
Jim Blandy's avatar
Jim Blandy committed
957
    {
958 959
      struct re_pattern_buffer *bufp;

960
      bufp = compile_pattern (string, &search_regs, trt, posix);
Jim Blandy's avatar
Jim Blandy committed
961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986

      immediate_quit = 1;	/* Quit immediately if user types ^G,
				   because letting this function finish
				   can take too long. */
      QUIT;			/* Do a pending quit right away,
				   to avoid paradoxical behavior */
      /* Get pointers and sizes of the two strings
	 that make up the visible portion of the buffer. */

      p1 = BEGV_ADDR;
      s1 = GPT - BEGV;
      p2 = GAP_END_ADDR;
      s2 = ZV - GPT;
      if (s1 < 0)
	{
	  p2 = p1;
	  s2 = ZV - BEGV;
	  s1 = 0;
	}
      if (s2 < 0)
	{
	  s1 = ZV - BEGV;
	  s2 = 0;
	}
      while (n < 0)
	{
987
	  int val;
988
	  val = re_search_2 (bufp, (char *) p1, s1, (char *) p2, s2,
989 990 991
			     pos - BEGV, lim - pos, &search_regs,
			     /* Don't allow match past current point */
			     pos - BEGV);
Jim Blandy's avatar
Jim Blandy committed
992
	  if (val == -2)
Karl Heuer's avatar
Karl Heuer committed
993 994 995
	    {
	      matcher_overflow ();
	    }
Jim Blandy's avatar
Jim Blandy committed
996 997 998
	  if (val >= 0)
	    {
	      j = BEGV;
Jim Blandy's avatar
Jim Blandy committed
999
	      for (i = 0; i < search_regs.num_regs; i++)
Jim Blandy's avatar
Jim Blandy committed
1000 1001 1002 1003 1004
		if (search_regs.start[i] >= 0)
		  {
		    search_regs.start[i] += j;
		    search_regs.end[i] += j;
		  }
1005
	      XSETBUFFER (last_thing_searched, current_buffer);
Jim Blandy's avatar
Jim Blandy committed
1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017
	      /* Set pos to the new position. */
	      pos = search_regs.start[0];
	    }
	  else
	    {
	      immediate_quit = 0;
	      return (n);
	    }
	  n++;
	}
      while (n > 0)
	{
1018
	  int val;
1019
	  val = re_search_2 (bufp, (char *) p1, s1, (char *) p2, s2,
1020 1021
			     pos - BEGV, lim - pos, &search_regs,
			     lim - BEGV);
Jim Blandy's avatar
Jim Blandy committed
1022
	  if (val == -2)
Karl Heuer's avatar
Karl Heuer committed
1023 1024 1025
	    {
	      matcher_overflow ();
	    }
Jim Blandy's avatar
Jim Blandy committed
1026 1027 1028
	  if (val >= 0)
	    {
	      j = BEGV;
Jim Blandy's avatar
Jim Blandy committed
1029
	      for (i = 0; i < search_regs.num_regs; i++)
Jim Blandy's avatar
Jim Blandy committed
1030 1031 1032 1033 1034
		if (search_regs.start[i] >= 0)
		  {
		    search_regs.start[i] += j;
		    search_regs.end[i] += j;
		  }
1035
	      XSETBUFFER (last_thing_searched, current_buffer);
Jim Blandy's avatar
Jim Blandy committed
1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055
	      pos = search_regs.end[0];
	    }
	  else
	    {
	      immediate_quit = 0;
	      return (0 - n);
	    }
	  n--;
	}
      immediate_quit = 0;
      return (pos);
    }
  else				/* non-RE case */
    {
#ifdef C_ALLOCA
      int BM_tab_space[0400];
      BM_tab = &BM_tab_space[0];
#else
      BM_tab = (int *) alloca (0400 * sizeof (int));
#endif
Karl Heuer's avatar
Karl Heuer committed
1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073
      {
	unsigned char *patbuf = (unsigned char *) alloca (len);
	pat = patbuf;
	while (--len >= 0)
	  {
	    /* If we got here and the RE flag is set, it's because we're
	       dealing with a regexp known to be trivial, so the backslash
	       just quotes the next character.  */
	    if (RE && *base_pat == '\\')
	      {
		len--;
		base_pat++;
	      }
	    *pat++ = (trt ? trt[*base_pat++] : *base_pat++);
	  }
	len = pat - patbuf;
	pat = base_pat = patbuf;
      }
Jim Blandy's avatar
Jim Blandy committed
1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121
      /* The general approach is that we are going to maintain that we know */
      /* the first (closest to the present position, in whatever direction */
      /* we're searching) character that could possibly be the last */
      /* (furthest from present position) character of a valid match.  We */
      /* advance the state of our knowledge by looking at that character */
      /* and seeing whether it indeed matches the last character of the */
      /* pattern.  If it does, we take a closer look.  If it does not, we */
      /* move our pointer (to putative last characters) as far as is */
      /* logically possible.  This amount of movement, which I call a */
      /* stride, will be the length of the pattern if the actual character */
      /* appears nowhere in the pattern, otherwise it will be the distance */
      /* from the last occurrence of that character to the end of the */
      /* pattern. */
      /* As a coding trick, an enormous stride is coded into the table for */
      /* characters that match the last character.  This allows use of only */
      /* a single test, a test for having gone past the end of the */
      /* permissible match region, to test for both possible matches (when */
      /* the stride goes past the end immediately) and failure to */
      /* match (where you get nudged past the end one stride at a time). */ 

      /* Here we make a "mickey mouse" BM table.  The stride of the search */
      /* is determined only by the last character of the putative match. */
      /* If that character does not match, we will stride the proper */
      /* distance to propose a match that superimposes it on the last */
      /* instance of a character that matches it (per trt), or misses */
      /* it entirely if there is none. */  

      dirlen = len * direction;
      infinity = dirlen - (lim + pos + len + len) * direction;
      if (direction < 0)
	pat = (base_pat += len - 1);
      BM_tab_base = BM_tab;
      BM_tab += 0400;
      j = dirlen;		/* to get it in a register */
      /* A character that does not appear in the pattern induces a */
      /* stride equal to the pattern length. */
      while (BM_tab_base != BM_tab)
	{
	  *--BM_tab = j;
	  *--BM_tab = j;
	  *--BM_tab = j;
	  *--BM_tab = j;
	}
      i = 0;
      while (i != infinity)
	{
	  j = pat[i]; i += direction;
	  if (i == dirlen) i = infinity;
1122
	  if (trt != 0)
Jim Blandy's avatar
Jim Blandy committed
1123 1124 1125 1126 1127 1128 1129
	    {
	      k = (j = trt[j]);
	      if (i == infinity)
		stride_for_teases = BM_tab[j];
	      BM_tab[j] = dirlen - i;
	      /* A translation table is accompanied by its inverse -- see */
	      /* comment following downcase_table for details */ 
1130
	      while ((j = (unsigned char) inverse_trt[j]) != k)
Jim Blandy's avatar
Jim Blandy committed
1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150
		BM_tab[j] = dirlen - i;
	    }
	  else
	    {
	      if (i == infinity)
		stride_for_teases = BM_tab[j];
	      BM_tab[j] = dirlen - i;
	    }
	  /* stride_for_teases tells how much to stride if we get a */
	  /* match on the far character but are subsequently */
	  /* disappointed, by recording what the stride would have been */
	  /* for that character if the last character had been */
	  /* different. */
	}
      infinity = dirlen - infinity;
      pos += dirlen - ((direction > 0) ? direction : 0);
      /* loop invariant - pos points at where last char (first char if reverse)
	 of pattern would align in a possible match.  */
      while (n != 0)
	{
1151 1152 1153 1154
	  /* It's been reported that some (broken) compiler thinks that
	     Boolean expressions in an arithmetic context are unsigned.
	     Using an explicit ?1:0 prevents this.  */
	  if ((lim - pos - ((direction > 0) ? 1 : 0)) * direction < 0)
Jim Blandy's avatar
Jim Blandy committed
1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183
	    return (n * (0 - direction));
	  /* First we do the part we can by pointers (maybe nothing) */
	  QUIT;
	  pat = base_pat;
	  limit = pos - dirlen + direction;
	  limit = ((direction > 0)
		   ? BUFFER_CEILING_OF (limit)
		   : BUFFER_FLOOR_OF (limit));
	  /* LIMIT is now the last (not beyond-last!) value
	     POS can take on without hitting edge of buffer or the gap.  */
	  limit = ((direction > 0)
		   ? min (lim - 1, min (limit, pos + 20000))
		   : max (lim, max (limit, pos - 20000)));
	  if ((limit - pos) * direction > 20)
	    {
	      p_limit = &FETCH_CHAR (limit);
	      p2 = (cursor = &FETCH_CHAR (pos));
	      /* In this loop, pos + cursor - p2 is the surrogate for pos */
	      while (1)		/* use one cursor setting as long as i can */
		{
		  if (direction > 0) /* worth duplicating */
		    {
		      /* Use signed comparison if appropriate
			 to make cursor+infinity sure to be > p_limit.
			 Assuming that the buffer lies in a range of addresses
			 that are all "positive" (as ints) or all "negative",
			 either kind of comparison will work as long
			 as we don't step by infinity.  So pick the kind
			 that works when we do step by infinity.  */
1184
		      if ((EMACS_INT) (p_limit + infinity) > (EMACS_INT) p_limit)
1185
			while ((EMACS_INT) cursor <= (EMACS_INT) p_limit)
Jim Blandy's avatar
Jim Blandy committed
1186 1187
			  cursor += BM_tab[*cursor];
		      else
1188
			while ((EMACS_UINT) cursor <= (EMACS_UINT) p_limit)
Jim Blandy's avatar
Jim Blandy committed
1189 1190 1191 1192
			  cursor += BM_tab[*cursor];
		    }
		  else
		    {
1193 1194
		      if ((EMACS_INT) (p_limit + infinity) < (EMACS_INT) p_limit)
			while ((EMACS_INT) cursor >= (EMACS_INT) p_limit)
Jim Blandy's avatar
Jim Blandy committed
1195 1196
			  cursor += BM_tab[*cursor];
		      else
1197
			while ((EMACS_UINT) cursor >= (EMACS_UINT) p_limit)
Jim Blandy's avatar
Jim Blandy committed
1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209
			  cursor += BM_tab[*cursor];
		    }
/* If you are here, cursor is beyond the end of the searched region. */
 /* This can happen if you match on the far character of the pattern, */
 /* because the "stride" of that character is infinity, a number able */
 /* to throw you well beyond the end of the search.  It can also */
 /* happen if you fail to match within the permitted region and would */
 /* otherwise try a character beyond that region */
		  if ((cursor - p_limit) * direction <= len)
		    break;	/* a small overrun is genuine */
		  cursor -= infinity; /* large overrun = hit */
		  i = dirlen - direction;
1210
		  if (trt != 0)
Jim Blandy's avatar
Jim Blandy committed
1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225
		    {
		      while ((i -= direction) + direction != 0)
			if (pat[i] != trt[*(cursor -= direction)])
			  break;
		    }
		  else
		    {
		      while ((i -= direction) + direction != 0)
			if (pat[i] != *(cursor -= direction))
			  break;
		    }
		  cursor += dirlen - i - direction;	/* fix cursor */
		  if (i + direction == 0)
		    {
		      cursor -= direction;
Jim Blandy's avatar
Jim Blandy committed
1226

1227 1228 1229 1230
		      set_search_regs (pos + cursor - p2 + ((direction > 0)
							    ? 1 - len : 0),
				       len);

Jim Blandy's avatar
Jim Blandy committed
1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262
		      if ((n -= direction) != 0)
			cursor += dirlen; /* to resume search */
		      else
			return ((direction > 0)
				? search_regs.end[0] : search_regs.start[0]);
		    }
		  else
		    cursor += stride_for_teases; /* <sigh> we lose -  */
		}
	      pos += cursor - p2;
	    }
	  else
	    /* Now we'll pick up a clump that has to be done the hard */
	    /* way because it covers a discontinuity */
	    {
	      limit = ((direction > 0)
		       ? BUFFER_CEILING_OF (pos - dirlen + 1)
		       : BUFFER_FLOOR_OF (pos - dirlen - 1));
	      limit = ((direction > 0)
		       ? min (limit + len, lim - 1)
		       : max (limit - len, lim));
	      /* LIMIT is now the last value POS can have
		 and still be valid for a possible match.  */
	      while (1)
		{
		  /* This loop can be coded for space rather than */
		  /* speed because it will usually run only once. */
		  /* (the reach is at most len + 21, and typically */
		  /* does not exceed len) */    
		  while ((limit - pos) * direction >= 0)
		    pos += BM_tab[FETCH_CHAR(pos)];
		  /* now run the same tests to distinguish going off the */
1263
		  /* end, a match or a phony match. */
Jim Blandy's avatar
Jim Blandy committed
1264 1265 1266 1267 1268 1269 1270 1271