syntax.c 47.2 KB
Newer Older
Richard M. Stallman's avatar
Richard M. Stallman committed
1
/* GNU Emacs routines to deal with syntax tables; also word and list parsing.
Karl Heuer's avatar
Karl Heuer committed
2
   Copyright (C) 1985, 1987, 1993, 1994 Free Software Foundation, Inc.
Richard M. Stallman's avatar
Richard M. Stallman 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
Jim Blandy's avatar
Jim Blandy committed
8
the Free Software Foundation; either version 2, or (at your option)
Richard M. Stallman's avatar
Richard M. Stallman committed
9 10 11 12 13 14 15 16 17 18 19 20
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
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


21
#include <config.h>
Richard M. Stallman's avatar
Richard M. Stallman committed
22 23 24 25 26 27 28 29
#include <ctype.h>
#include "lisp.h"
#include "commands.h"
#include "buffer.h"
#include "syntax.h"

Lisp_Object Qsyntax_table_p;

30 31 32
static void scan_sexps_forward ();
static int char_quoted ();

Richard M. Stallman's avatar
Richard M. Stallman committed
33 34
int words_include_escapes;

35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
/* This is the internal form of the parse state used in parse-partial-sexp.  */

struct lisp_parse_state
  {
    int depth;		/* Depth at end of parsing */
    int instring;	/* -1 if not within string, else desired terminator. */
    int incomment;	/* Nonzero if within a comment at end of parsing */
    int comstyle;	/* comment style a=0, or b=1 */
    int quoted;		/* Nonzero if just after an escape char at end of parsing */
    int thislevelstart;	/* Char number of most recent start-of-expression at current level */
    int prevlevelstart; /* Char number of start of containing expression */
    int location;	/* Char number at which parsing stopped. */
    int mindepth;	/* Minimum depth seen while scanning.  */
    int comstart;	/* Position just after last comment starter.  */
  };

51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
/* These variables are a cache for finding the start of a defun.
   find_start_pos is the place for which the defun start was found.
   find_start_value is the defun start position found for it.
   find_start_buffer is the buffer it was found in.
   find_start_begv is the BEGV value when it was found.
   find_start_modiff is the value of MODIFF when it was found.  */

static int find_start_pos;
static int find_start_value;
static struct buffer *find_start_buffer;
static int find_start_begv;
static int find_start_modiff;

/* Find a defun-start that is the last one before POS (or nearly the last).
   We record what we find, so that another call in the same area
   can return the same value right away.  */

static int
find_defun_start (pos)
     int pos;
{
  int tem;
  int shortage;

  /* Use previous finding, if it's valid and applies to this inquiry.  */
  if (current_buffer == find_start_buffer
      /* Reuse the defun-start even if POS is a little farther on.
	 POS might be in the next defun, but that's ok.
	 Our value may not be the best possible, but will still be usable.  */
      && pos <= find_start_pos + 1000
      && pos >= find_start_value
      && BEGV == find_start_begv
      && MODIFF == find_start_modiff)
    return find_start_value;

  /* Back up to start of line.  */
87
  tem = scan_buffer ('\n', pos, -1, &shortage, 1);
88 89 90 91 92 93 94

  while (tem > BEGV)
    {
      /* Open-paren at start of line means we found our defun-start.  */
      if (SYNTAX (FETCH_CHAR (tem)) == Sopen)
	break;
      /* Move to beg of previous line.  */
95
      tem = scan_buffer ('\n', tem, -2, &shortage, 1);
96 97 98 99 100 101 102 103 104 105 106 107
    }

  /* Record what we found, for the next try.  */
  find_start_value = tem;
  find_start_buffer = current_buffer;
  find_start_modiff = MODIFF;
  find_start_begv = BEGV;
  find_start_pos = pos;

  return find_start_value;
}

Richard M. Stallman's avatar
Richard M. Stallman committed
108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124
DEFUN ("syntax-table-p", Fsyntax_table_p, Ssyntax_table_p, 1, 1, 0,
  "Return t if ARG is a syntax table.\n\
Any vector of 256 elements will do.")
  (obj)
     Lisp_Object obj;
{
  if (XTYPE (obj) == Lisp_Vector && XVECTOR (obj)->size == 0400)
    return Qt;
  return Qnil;
}

Lisp_Object
check_syntax_table (obj)
     Lisp_Object obj;
{
  register Lisp_Object tem;
  while (tem = Fsyntax_table_p (obj),
Jim Blandy's avatar
Jim Blandy committed
125
	 NILP (tem))
126
    obj = wrong_type_argument (Qsyntax_table_p, obj);
Richard M. Stallman's avatar
Richard M. Stallman committed
127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157
  return obj;
}   


DEFUN ("syntax-table", Fsyntax_table, Ssyntax_table, 0, 0, 0,
  "Return the current syntax table.\n\
This is the one specified by the current buffer.")
  ()
{
  return current_buffer->syntax_table;
}

DEFUN ("standard-syntax-table", Fstandard_syntax_table,
   Sstandard_syntax_table, 0, 0, 0,
  "Return the standard syntax table.\n\
This is the one used for new buffers.")
  ()
{
  return Vstandard_syntax_table;
}

DEFUN ("copy-syntax-table", Fcopy_syntax_table, Scopy_syntax_table, 0, 1, 0,
  "Construct a new syntax table and return it.\n\
It is a copy of the TABLE, which defaults to the standard syntax table.")
  (table)
     Lisp_Object table;
{
  Lisp_Object size, val;
  XFASTINT (size) = 0400;
  XFASTINT (val) = 0;
  val = Fmake_vector (size, val);
Jim Blandy's avatar
Jim Blandy committed
158
  if (!NILP (table))
Richard M. Stallman's avatar
Richard M. Stallman committed
159
    table = check_syntax_table (table);
Jim Blandy's avatar
Jim Blandy committed
160
  else if (NILP (Vstandard_syntax_table))
Richard M. Stallman's avatar
Richard M. Stallman committed
161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178
    /* Can only be null during initialization */
    return val;
  else table = Vstandard_syntax_table;

  bcopy (XVECTOR (table)->contents,
	 XVECTOR (val)->contents, 0400 * sizeof (Lisp_Object));
  return val;
}

DEFUN ("set-syntax-table", Fset_syntax_table, Sset_syntax_table, 1, 1, 0,
  "Select a new syntax table for the current buffer.\n\
One argument, a syntax table.")
  (table)
     Lisp_Object table;
{
  table = check_syntax_table (table);
  current_buffer->syntax_table = table;
  /* Indicate that this buffer now has a specified syntax table.  */
179 180
  current_buffer->local_var_flags
    |= XFASTINT (buffer_local_flags.syntax_table);
Richard M. Stallman's avatar
Richard M. Stallman committed
181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199
  return table;
}

/* Convert a letter which signifies a syntax code
 into the code it signifies.
 This is used by modify-syntax-entry, and other things. */

unsigned char syntax_spec_code[0400] =
  { 0377, 0377, 0377, 0377, 0377, 0377, 0377, 0377,
    0377, 0377, 0377, 0377, 0377, 0377, 0377, 0377,
    0377, 0377, 0377, 0377, 0377, 0377, 0377, 0377,
    0377, 0377, 0377, 0377, 0377, 0377, 0377, 0377,
    (char) Swhitespace, 0377, (char) Sstring, 0377,
        (char) Smath, 0377, 0377, (char) Squote,
    (char) Sopen, (char) Sclose, 0377, 0377,
	0377, (char) Swhitespace, (char) Spunct, (char) Scharquote,
    0377, 0377, 0377, 0377, 0377, 0377, 0377, 0377,
    0377, 0377, 0377, 0377,
	(char) Scomment, 0377, (char) Sendcomment, 0377,
200
    (char) Sinherit, 0377, 0377, 0377, 0377, 0377, 0377, 0377,   /* @, A ... */
Richard M. Stallman's avatar
Richard M. Stallman committed
201 202 203 204 205 206 207 208 209 210 211
    0377, 0377, 0377, 0377, 0377, 0377, 0377, 0377,
    0377, 0377, 0377, 0377, 0377, 0377, 0377, (char) Sword,
    0377, 0377, 0377, 0377, (char) Sescape, 0377, 0377, (char) Ssymbol,
    0377, 0377, 0377, 0377, 0377, 0377, 0377, 0377,   /* `, a, ... */
    0377, 0377, 0377, 0377, 0377, 0377, 0377, 0377,
    0377, 0377, 0377, 0377, 0377, 0377, 0377, (char) Sword,
    0377, 0377, 0377, 0377, 0377, 0377, 0377, 0377
  };

/* Indexed by syntax code, give the letter that describes it. */

212
char syntax_code_spec[14] =
Richard M. Stallman's avatar
Richard M. Stallman committed
213
  {
214
    ' ', '.', 'w', '_', '(', ')', '\'', '\"', '$', '\\', '/', '<', '>', '@'
Richard M. Stallman's avatar
Richard M. Stallman committed
215 216 217 218 219 220 221 222 223 224 225
  };

DEFUN ("char-syntax", Fchar_syntax, Schar_syntax, 1, 1, 0,
  "Return the syntax code of CHAR, described by a character.\n\
For example, if CHAR is a word constituent, the character `?w' is returned.\n\
The characters that correspond to various syntax codes\n\
are listed in the documentation of `modify-syntax-entry'.")
  (ch)
     Lisp_Object ch;
{
  CHECK_NUMBER (ch, 0);
226 227 228 229 230 231 232 233 234 235 236 237 238 239
  return make_number (syntax_code_spec[(int) SYNTAX (XINT (ch))]);
}

DEFUN ("matching-paren", Fmatching_paren, Smatching_paren, 1, 1, 0,
  "Return the matching parenthesis of CHAR, or nil if none.")
  (ch)
     Lisp_Object ch;
{
  int code;
  CHECK_NUMBER (ch, 0);
  code = SYNTAX (XINT (ch));
  if (code == Sopen && code == Sclose)
    return make_number (SYNTAX_MATCH (XINT (ch)));
  return Qnil;
Richard M. Stallman's avatar
Richard M. Stallman committed
240 241 242 243 244 245
}

/* This comment supplies the doc string for modify-syntax-entry,
   for make-docfile to see.  We cannot put this in the real DEFUN
   due to limits in the Unix cpp.

246
DEFUN ("modify-syntax-entry", foo, bar, 2, 3, 0,
Richard M. Stallman's avatar
Richard M. Stallman committed
247 248 249 250
  "Set syntax for character CHAR according to string S.\n\
The syntax is changed only for table TABLE, which defaults to\n\
 the current buffer's syntax table.\n\
The first character of S should be one of the following:\n\
Jim Blandy's avatar
Jim Blandy committed
251 252 253 254 255
  Space or -  whitespace syntax.    w   word constituent.\n\
  _           symbol constituent.   .   punctuation.\n\
  (           open-parenthesis.     )   close-parenthesis.\n\
  \"           string quote.         \\   escape.\n\
  $           paired delimiter.     '   expression quote or prefix operator.\n\
256
  <           comment starter.      >   comment ender.\n\
257
  /           character-quote.      @   inherit from `standard-syntax-table'.\n\
258
\n\
Richard M. Stallman's avatar
Richard M. Stallman committed
259 260 261 262 263
Only single-character comment start and end sequences are represented thus.\n\
Two-character sequences are represented as described below.\n\
The second character of S is the matching parenthesis,\n\
 used only if the first character is `(' or `)'.\n\
Any additional characters are flags.\n\
264
Defined flags are the characters 1, 2, 3, 4, b, and p.\n\
Richard M. Stallman's avatar
Richard M. Stallman committed
265 266 267 268
 1 means C is the start of a two-char comment start sequence.\n\
 2 means C is the second character of such a sequence.\n\
 3 means C is the start of a two-char comment end sequence.\n\
 4 means C is the second character of such a sequence.\n\
269 270 271
\n\
There can be up to two orthogonal comment sequences. This is to support\n\
language modes such as C++.  By default, all comment sequences are of style\n\
272 273
a, but you can set the comment sequence style to b (on the second character\n\
of a comment-start, or the first character of a comment-end sequence) using\n\
274 275 276 277 278
this flag:\n\
 b means C is part of comment sequence b.\n\
\n\
 p means C is a prefix character for `backward-prefix-chars';\n\
   such characters are treated as whitespace when they occur\n\
Richard M. Stallman's avatar
Richard M. Stallman committed
279
   between expressions.")
280
  (char, s, table)
Richard M. Stallman's avatar
Richard M. Stallman committed
281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297
*/

DEFUN ("modify-syntax-entry", Fmodify_syntax_entry, Smodify_syntax_entry, 2, 3, 
  /* I really don't know why this is interactive
     help-form should at least be made useful whilst reading the second arg
   */
  "cSet syntax for character: \nsSet syntax for %s to: ",
  0 /* See immediately above */)
  (c, newentry, syntax_table)
     Lisp_Object c, newentry, syntax_table;
{
  register unsigned char *p, match;
  register enum syntaxcode code;
  Lisp_Object val;

  CHECK_NUMBER (c, 0);
  CHECK_STRING (newentry, 1);
Jim Blandy's avatar
Jim Blandy committed
298
  if (NILP (syntax_table))
Richard M. Stallman's avatar
Richard M. Stallman committed
299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334
    syntax_table = current_buffer->syntax_table;
  else
    syntax_table = check_syntax_table (syntax_table);

  p = XSTRING (newentry)->data;
  code = (enum syntaxcode) syntax_spec_code[*p++];
  if (((int) code & 0377) == 0377)
    error ("invalid syntax description letter: %c", c);

  match = *p;
  if (match) p++;
  if (match == ' ') match = 0;

  XFASTINT (val) = (match << 8) + (int) code;
  while (*p)
    switch (*p++)
      {
      case '1':
	XFASTINT (val) |= 1 << 16;
	break;

      case '2':
	XFASTINT (val) |= 1 << 17;
	break;

      case '3':
	XFASTINT (val) |= 1 << 18;
	break;

      case '4':
	XFASTINT (val) |= 1 << 19;
	break;

      case 'p':
	XFASTINT (val) |= 1 << 20;
	break;
335 336 337 338

      case 'b':
	XFASTINT (val) |= 1 << 21;
	break;
Richard M. Stallman's avatar
Richard M. Stallman committed
339 340 341 342 343 344 345 346 347
      }
	
  XVECTOR (syntax_table)->contents[0xFF & XINT (c)] = val;

  return Qnil;
}

/* Dump syntax table to buffer in human-readable format */

348
static void
Richard M. Stallman's avatar
Richard M. Stallman committed
349 350 351 352
describe_syntax (value)
    Lisp_Object value;
{
  register enum syntaxcode code;
353
  char desc, match, start1, start2, end1, end2, prefix, comstyle;
Richard M. Stallman's avatar
Richard M. Stallman committed
354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370
  char str[2];

  Findent_to (make_number (16), make_number (1));

  if (XTYPE (value) != Lisp_Int)
    {
      insert_string ("invalid");
      return;
    }

  code = (enum syntaxcode) (XINT (value) & 0377);
  match = (XINT (value) >> 8) & 0377;
  start1 = (XINT (value) >> 16) & 1;
  start2 = (XINT (value) >> 17) & 1;
  end1 = (XINT (value) >> 18) & 1;
  end2 = (XINT (value) >> 19) & 1;
  prefix = (XINT (value) >> 20) & 1;
371
  comstyle = (XINT (value) >> 21) & 1;
Richard M. Stallman's avatar
Richard M. Stallman 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

  if ((int) code < 0 || (int) code >= (int) Smax)
    {
      insert_string ("invalid");
      return;
    }
  desc = syntax_code_spec[(int) code];

  str[0] = desc, str[1] = 0;
  insert (str, 1);

  str[0] = match ? match : ' ';
  insert (str, 1);


  if (start1)
    insert ("1", 1);
  if (start2)
    insert ("2", 1);

  if (end1)
    insert ("3", 1);
  if (end2)
    insert ("4", 1);

  if (prefix)
    insert ("p", 1);
399 400
  if (comstyle)
    insert ("b", 1);
Richard M. Stallman's avatar
Richard M. Stallman committed
401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435

  insert_string ("\twhich means: ");

#ifdef SWITCH_ENUM_BUG
  switch ((int) code)
#else
  switch (code)
#endif
    {
    case Swhitespace:
      insert_string ("whitespace"); break;
    case Spunct:
      insert_string ("punctuation"); break;
    case Sword:
      insert_string ("word"); break;
    case Ssymbol:
      insert_string ("symbol"); break;
    case Sopen:
      insert_string ("open"); break;
    case Sclose:
      insert_string ("close"); break;
    case Squote:
      insert_string ("quote"); break;
    case Sstring:
      insert_string ("string"); break;
    case Smath:
      insert_string ("math"); break;
    case Sescape:
      insert_string ("escape"); break;
    case Scharquote:
      insert_string ("charquote"); break;
    case Scomment:
      insert_string ("comment"); break;
    case Sendcomment:
      insert_string ("endcomment"); break;
436 437
    case Sinherit:
      insert_string ("inherit"); break;
Richard M. Stallman's avatar
Richard M. Stallman committed
438 439 440 441 442 443 444 445
    default:
      insert_string ("invalid");
      return;
    }

  if (match)
    {
      insert_string (", matches ");
446
      insert_char (match);
Richard M. Stallman's avatar
Richard M. Stallman committed
447 448 449 450 451 452 453 454 455 456 457
    }

  if (start1)
    insert_string (",\n\t  is the first character of a comment-start sequence");
  if (start2)
    insert_string (",\n\t  is the second character of a comment-start sequence");

  if (end1)
    insert_string (",\n\t  is the first character of a comment-end sequence");
  if (end2)
    insert_string (",\n\t  is the second character of a comment-end sequence");
458 459 460
  if (comstyle)
    insert_string (" (comment style b)");

Richard M. Stallman's avatar
Richard M. Stallman committed
461 462 463 464 465 466
  if (prefix)
    insert_string (",\n\t  is a prefix character for `backward-prefix-chars'");

  insert_string ("\n");
}

467
static Lisp_Object
Richard M. Stallman's avatar
Richard M. Stallman committed
468 469 470 471 472
describe_syntax_1 (vector)
     Lisp_Object vector;
{
  struct buffer *old = current_buffer;
  set_buffer_internal (XBUFFER (Vstandard_output));
473
  describe_vector (vector, Qnil, describe_syntax, 0, Qnil);
Richard M. Stallman's avatar
Richard M. Stallman committed
474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586
  set_buffer_internal (old);
  return Qnil;
}

DEFUN ("describe-syntax", Fdescribe_syntax, Sdescribe_syntax, 0, 0, "",
  "Describe the syntax specifications in the syntax table.\n\
The descriptions are inserted in a buffer, which is then displayed.")
  ()
{
  internal_with_output_to_temp_buffer
     ("*Help*", describe_syntax_1, current_buffer->syntax_table);

  return Qnil;
}

/* Return the position across COUNT words from FROM.
   If that many words cannot be found before the end of the buffer, return 0.
   COUNT negative means scan backward and stop at word beginning.  */

scan_words (from, count)
     register int from, count;
{
  register int beg = BEGV;
  register int end = ZV;
  register int code;

  immediate_quit = 1;
  QUIT;

  while (count > 0)
    {
      while (1)
	{
	  if (from == end)
	    {
	      immediate_quit = 0;
	      return 0;
	    }
	  code = SYNTAX (FETCH_CHAR (from));
	  if (words_include_escapes
	      && (code == Sescape || code == Scharquote))
	    break;
	  if (code == Sword)
	    break;
	  from++;
	}
      while (1)
	{
	  if (from == end) break;
	  code = SYNTAX (FETCH_CHAR (from));
	  if (!(words_include_escapes
		&& (code == Sescape || code == Scharquote)))
	    if (code != Sword)
	      break;
	  from++;
	}
      count--;
    }
  while (count < 0)
    {
      while (1)
	{
	  if (from == beg)
	    {
	      immediate_quit = 0;
	      return 0;
	    }
	  code = SYNTAX (FETCH_CHAR (from - 1));
	  if (words_include_escapes
	      && (code == Sescape || code == Scharquote))
	    break;
	  if (code == Sword)
	    break;
	  from--;
	}
      while (1)
	{
	  if (from == beg) break;
	  code = SYNTAX (FETCH_CHAR (from - 1));
	  if (!(words_include_escapes
		&& (code == Sescape || code == Scharquote)))
	    if (code != Sword)
	      break;
	  from--;
	}
      count++;
    }

  immediate_quit = 0;

  return from;
}

DEFUN ("forward-word", Fforward_word, Sforward_word, 1, 1, "p",
  "Move point forward ARG words (backward if ARG is negative).\n\
Normally returns t.\n\
If an edge of the buffer is reached, point is left there\n\
and nil is returned.")
  (count)
     Lisp_Object count;
{
  int val;
  CHECK_NUMBER (count, 0);

  if (!(val = scan_words (point, XINT (count))))
    {
      SET_PT (XINT (count) > 0 ? ZV : BEGV);
      return Qnil;
    }
  SET_PT (val);
  return Qt;
}

587 588 589
DEFUN ("forward-comment", Fforward_comment, Sforward_comment, 1, 1, 0,
  "Move forward across up to N comments.  If N is negative, move backward.\n\
Stop scanning if we find something other than a comment or whitespace.\n\
590
Set point to where scanning stops.\n\
591 592 593
If N comments are found as expected, with nothing except whitespace\n\
between them, return t; otherwise return nil.")
  (count)
594
     Lisp_Object count;
595 596 597 598 599 600
{
  register int from;
  register int stop;
  register int c;
  register enum syntaxcode code;
  int comstyle = 0;	    /* style of comment encountered */
601
  int found;
602 603 604 605
  int count1;

  CHECK_NUMBER (count, 0);
  count1 = XINT (count);
606 607 608 609 610 611

  immediate_quit = 1;
  QUIT;

  from = PT;

612
  while (count1 > 0)
613 614
    {
      stop = ZV;
615
      do
616
	{
617 618 619 620 621
	  if (from == stop)
	    {
	      SET_PT (from);
	      return Qnil;
	    }
622 623 624 625 626 627 628
	  c = FETCH_CHAR (from);
	  code = SYNTAX (c);
	  from++;
	  comstyle = 0;
	  if (from < stop && SYNTAX_COMSTART_FIRST (c)
	      && SYNTAX_COMSTART_SECOND (FETCH_CHAR (from)))
	    {
629 630
	      /* We have encountered a comment start sequence and we 
		 are ignoring all text inside comments.  We must record
631 632
		 the comment style this sequence begins so that later,
		 only a comment end of the same style actually ends
633
		 the comment section.  */
634 635 636 637
	      code = Scomment;
	      comstyle = SYNTAX_COMMENT_STYLE (FETCH_CHAR (from));
	      from++;
	    }
638 639 640 641 642 643 644 645 646 647 648 649
	}
      while (code == Swhitespace || code == Sendcomment);
      if (code != Scomment)
	{
	  immediate_quit = 0;
	  SET_PT (from - 1);
	  return Qnil;
	}
      /* We're at the start of a comment.  */
      while (1)
	{
	  if (from == stop)
650 651
	    {
	      immediate_quit = 0;
652
	      SET_PT (from);
653 654
	      return Qnil;
	    }
655 656 657 658 659 660 661 662 663 664 665 666 667 668 669
	  c = FETCH_CHAR (from);
	  if (SYNTAX (c) == Sendcomment
	      && SYNTAX_COMMENT_STYLE (c) == comstyle)
	    /* we have encountered a comment end of the same style
	       as the comment sequence which began this comment
	       section */
	    break;
	  from++;
	  if (from < stop && SYNTAX_COMEND_FIRST (c)
	      && SYNTAX_COMEND_SECOND (FETCH_CHAR (from))
	      && SYNTAX_COMMENT_STYLE (c) == comstyle)
	    /* we have encountered a comment end of the same style
	       as the comment sequence which began this comment
	       section */
	    { from++; break; }
670
	}
671
      /* We have skipped one comment.  */
672
      count1--;
673 674
    }

675
  while (count1 < 0)
676 677 678 679 680 681 682 683 684 685 686 687 688
    {
      stop = BEGV;
      while (from > stop)
	{
	  int quoted;

	  from--;
	  quoted = char_quoted (from);
	  if (quoted)
	    from--;
	  c = FETCH_CHAR (from);
	  code = SYNTAX (c);
	  comstyle = 0;
689 690
	  if (code == Sendcomment)
	    comstyle = SYNTAX_COMMENT_STYLE (c);
691 692 693 694
	  if (from > stop && SYNTAX_COMEND_SECOND (c)
	      && SYNTAX_COMEND_FIRST (FETCH_CHAR (from - 1))
	      && !char_quoted (from - 1))
	    {
695
	      /* We must record the comment style encountered so that
696
		 later, we can match only the proper comment begin
697
		 sequence of the same style.  */
698 699 700 701 702 703 704
	      code = Sendcomment;
	      comstyle = SYNTAX_COMMENT_STYLE (FETCH_CHAR (from - 1));
	      from--;
	    }

	  if (code == Sendcomment && !quoted)
	    {
705
#if 0
706 707 708 709 710 711 712 713 714 715 716 717 718
	      if (code != SYNTAX (c))
		/* For a two-char comment ender, we can assume
		   it does end a comment.  So scan back in a simple way.  */
		{
		  if (from != stop) from--;
		  while (1)
		    {
		      if (SYNTAX (c = FETCH_CHAR (from)) == Scomment
			  && SYNTAX_COMMENT_STYLE (c) == comstyle)
			break;
		      if (from == stop)
			{
			  immediate_quit = 0;
719
			  SET_PT (from);
720 721 722 723 724 725 726 727 728 729 730
			  return Qnil;
			}
		      from--;
		      if (SYNTAX_COMSTART_SECOND (c)
			  && SYNTAX_COMSTART_FIRST (FETCH_CHAR (from))
			  && SYNTAX_COMMENT_STYLE (c) == comstyle
			  && !char_quoted (from))
			break;
		    }
		  break;
		}
731
#endif /* 0 */
732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801

	      /* Look back, counting the parity of string-quotes,
		 and recording the comment-starters seen.
		 When we reach a safe place, assume that's not in a string;
		 then step the main scan to the earliest comment-starter seen
		 an even number of string quotes away from the safe place.

		 OFROM[I] is position of the earliest comment-starter seen
		 which is I+2X quotes from the comment-end.
		 PARITY is current parity of quotes from the comment end.  */
	      {
		int parity = 0;
		char my_stringend = 0;
		int string_lossage = 0;
		int comment_end = from;
		int comstart_pos = 0;
		int comstart_parity = 0;

		/* At beginning of range to scan, we're outside of strings;
		   that determines quote parity to the comment-end.  */
		while (from != stop)
		  {
		    /* Move back and examine a character.  */
		    from--;

		    c = FETCH_CHAR (from);
		    code = SYNTAX (c);

		    /* If this char is the second of a 2-char comment sequence,
		       back up and give the pair the appropriate syntax.  */
		    if (from > stop && SYNTAX_COMEND_SECOND (c)
			&& SYNTAX_COMEND_FIRST (FETCH_CHAR (from - 1)))
		      {
			code = Sendcomment;
			from--;
		      }
			
		    else if (from > stop && SYNTAX_COMSTART_SECOND (c)
			     && SYNTAX_COMSTART_FIRST (FETCH_CHAR (from - 1))
			     && comstyle == SYNTAX_COMMENT_STYLE (c))
		      {
			code = Scomment;
			from--;
		      }

		    /* Ignore escaped characters.  */
		    if (char_quoted (from))
		      continue;

		    /* Track parity of quotes.  */
		    if (code == Sstring)
		      {
			parity ^= 1;
			if (my_stringend == 0)
			  my_stringend = c;
			/* If we have two kinds of string delimiters.
			   There's no way to grok this scanning backwards.  */
			else if (my_stringend != c)
			  string_lossage = 1;
		      }

		    /* Record comment-starters according to that
		       quote-parity to the comment-end.  */
		    if (code == Scomment)
		      {
			comstart_parity = parity;
			comstart_pos = from;
		      }

		    /* If we find another earlier comment-ender,
802
		       any comment-starts earlier than that don't count
803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831
		       (because they go with the earlier comment-ender).  */
		    if (code == Sendcomment
			&& SYNTAX_COMMENT_STYLE (FETCH_CHAR (from)) == comstyle)
		      break;

		    /* Assume a defun-start point is outside of strings.  */
		    if (code == Sopen
			&& (from == stop || FETCH_CHAR (from - 1) == '\n'))
		      break;
		  }

		if (comstart_pos == 0)
		  from = comment_end;
		/* If the earliest comment starter
		   is followed by uniform paired string quotes or none,
		   we know it can't be inside a string
		   since if it were then the comment ender would be inside one.
		   So it does start a comment.  Skip back to it.  */
		else if (comstart_parity == 0 && !string_lossage)
		  from = comstart_pos;
		else
		  {
		    /* We had two kinds of string delimiters mixed up
		       together.  Decode this going forwards.
		       Scan fwd from the previous comment ender
		       to the one in question; this records where we
		       last passed a comment starter.  */
		    struct lisp_parse_state state;
		    scan_sexps_forward (&state, find_defun_start (comment_end),
832
					comment_end - 1, -10000, 0, Qnil, 0);
833 834 835 836 837 838 839
		    if (state.incomment)
		      from = state.comstart;
		    else
		      /* We can't grok this as a comment; scan it normally.  */
		      from = comment_end;
		  }
	      }
840 841
	      /* We have skipped one comment.  */
	      break;
842
	    }
843
	  else if ((code != Swhitespace && code != Scomment) || quoted)
844 845
	    {
	      immediate_quit = 0;
846
	      SET_PT (from + 1);
847 848 849 850
	      return Qnil;
	    }
	}

851
      count1++;
852 853 854 855 856 857 858
    }

  SET_PT (from);
  immediate_quit = 0;
  return Qt;
}

Richard M. Stallman's avatar
Richard M. Stallman committed
859 860 861 862 863 864 865 866 867 868 869 870 871 872 873
int parse_sexp_ignore_comments;

Lisp_Object
scan_lists (from, count, depth, sexpflag)
     register int from;
     int count, depth, sexpflag;
{
  Lisp_Object val;
  register int stop;
  register int c;
  char stringterm;
  int quoted;
  int mathexit = 0;
  register enum syntaxcode code;
  int min_depth = depth;    /* Err out if depth gets less than this. */
874
  int comstyle = 0;	    /* style of comment encountered */
Richard M. Stallman's avatar
Richard M. Stallman committed
875 876 877 878 879 880 881 882 883 884 885 886

  if (depth > 0) min_depth = 0;

  immediate_quit = 1;
  QUIT;

  while (count > 0)
    {
      stop = ZV;
      while (from < stop)
	{
	  c = FETCH_CHAR (from);
887
	  code = SYNTAX (c);
Richard M. Stallman's avatar
Richard M. Stallman committed
888 889 890 891
	  from++;
	  if (from < stop && SYNTAX_COMSTART_FIRST (c)
	      && SYNTAX_COMSTART_SECOND (FETCH_CHAR (from))
	      && parse_sexp_ignore_comments)
892 893 894 895 896 897 898 899 900 901 902
	    {
	      /* we have encountered a comment start sequence and we 
		 are ignoring all text inside comments. we must record
		 the comment style this sequence begins so that later,
		 only a comment end of the same style actually ends
		 the comment section */
	      code = Scomment;
	      comstyle = SYNTAX_COMMENT_STYLE (FETCH_CHAR (from));
	      from++;
	    }
	  
Richard M. Stallman's avatar
Richard M. Stallman committed
903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923
	  if (SYNTAX_PREFIX (c))
	    continue;

#ifdef SWITCH_ENUM_BUG
	  switch ((int) code)
#else
	  switch (code)
#endif
	    {
	    case Sescape:
	    case Scharquote:
	      if (from == stop) goto lose;
	      from++;
	      /* treat following character as a word constituent */
	    case Sword:
	    case Ssymbol:
	      if (depth || !sexpflag) break;
	      /* This word counts as a sexp; return at end of it. */
	      while (from < stop)
		{
#ifdef SWITCH_ENUM_BUG
924
		  switch ((int) SYNTAX (FETCH_CHAR (from)))
Richard M. Stallman's avatar
Richard M. Stallman committed
925
#else
926
		  switch (SYNTAX (FETCH_CHAR (from)))
Richard M. Stallman's avatar
Richard M. Stallman committed
927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948
#endif
		    {
		    case Scharquote:
		    case Sescape:
		      from++;
		      if (from == stop) goto lose;
		      break;
		    case Sword:
		    case Ssymbol:
		    case Squote:
		      break;
		    default:
		      goto done;
		    }
		  from++;
		}
	      goto done;

	    case Scomment:
	      if (!parse_sexp_ignore_comments) break;
	      while (1)
		{
949 950 951 952 953 954
		  if (from == stop)
		    {
		      if (depth == 0)
			goto done;
		      goto lose;
		    }
955 956 957 958 959 960
		  c = FETCH_CHAR (from);
		  if (SYNTAX (c) == Sendcomment
		      && SYNTAX_COMMENT_STYLE (c) == comstyle)
		    /* we have encountered a comment end of the same style
		       as the comment sequence which began this comment
		       section */
Richard M. Stallman's avatar
Richard M. Stallman committed
961 962 963
		    break;
		  from++;
		  if (from < stop && SYNTAX_COMEND_FIRST (c)
964 965 966 967 968
		      && SYNTAX_COMEND_SECOND (FETCH_CHAR (from))
		      && SYNTAX_COMMENT_STYLE (c) == comstyle)
		    /* we have encountered a comment end of the same style
		       as the comment sequence which began this comment
		       section */
Richard M. Stallman's avatar
Richard M. Stallman committed
969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002
		    { from++; break; }
		}
	      break;

	    case Smath:
	      if (!sexpflag)
		break;
	      if (from != stop && c == FETCH_CHAR (from))
		from++;
	      if (mathexit)
		{
		  mathexit = 0;
		  goto close1;
		}
	      mathexit = 1;

	    case Sopen:
	      if (!++depth) goto done;
	      break;

	    case Sclose:
	    close1:
	      if (!--depth) goto done;
	      if (depth < min_depth)
		error ("Containing expression ends prematurely");
	      break;

	    case Sstring:
	      stringterm = FETCH_CHAR (from - 1);
	      while (1)
		{
		  if (from >= stop) goto lose;
		  if (FETCH_CHAR (from) == stringterm) break;
#ifdef SWITCH_ENUM_BUG
1003
		  switch ((int) SYNTAX (FETCH_CHAR (from)))
Richard M. Stallman's avatar
Richard M. Stallman committed
1004
#else
1005
		  switch (SYNTAX (FETCH_CHAR (from)))
Richard M. Stallman's avatar
Richard M. Stallman committed
1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
#endif
		    {
		    case Scharquote:
		    case Sescape:
		      from++;
		    }
		  from++;
		}
	      from++;
	      if (!depth && sexpflag) goto done;
	      break;
	    }
	}

      /* Reached end of buffer.  Error if within object, return nil if between */
      if (depth) goto lose;

      immediate_quit = 0;
      return Qnil;

      /* End of object reached */
    done:
      count--;
    }

  while (count < 0)
    {
      stop = BEGV;
      while (from > stop)
	{
	  from--;
	  if (quoted = char_quoted (from))
	    from--;
	  c = FETCH_CHAR (from);
	  code = SYNTAX (c);
1041 1042 1043
	  comstyle = 0;
	  if (code == Sendcomment)
	    comstyle = SYNTAX_COMMENT_STYLE (c);
Richard M. Stallman's avatar
Richard M. Stallman committed
1044 1045 1046 1047
	  if (from > stop && SYNTAX_COMEND_SECOND (c)
	      && SYNTAX_COMEND_FIRST (FETCH_CHAR (from - 1))
	      && !char_quoted (from - 1)
	      && parse_sexp_ignore_comments)
1048 1049 1050 1051 1052 1053 1054 1055 1056
	    {
	      /* we must record the comment style encountered so that
		 later, we can match only the proper comment begin
		 sequence of the same style */
	      code = Sendcomment;
	      comstyle = SYNTAX_COMMENT_STYLE (FETCH_CHAR (from - 1));
	      from--;
	    }
	  
Richard M. Stallman's avatar
Richard M. Stallman committed
1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074
	  if (SYNTAX_PREFIX (c))
	    continue;

#ifdef SWITCH_ENUM_BUG
	  switch ((int) (quoted ? Sword : code))
#else
	  switch (quoted ? Sword : code)
#endif
	    {
	    case Sword:
	    case Ssymbol:
	      if (depth || !sexpflag) break;
	      /* This word counts as a sexp; count object finished after passing it. */
	      while (from > stop)
		{
		  quoted = char_quoted (from - 1);
		  if (quoted)
		    from--;
1075 1076 1077
		  if (! (quoted || SYNTAX (FETCH_CHAR (from - 1)) == Sword
			 || SYNTAX (FETCH_CHAR (from - 1)) == Ssymbol
			 || SYNTAX (FETCH_CHAR (from - 1)) == Squote))
Richard M. Stallman's avatar
Richard M. Stallman committed
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
            	    goto done2;
		  from--;
		}
	      goto done2;

	    case Smath:
	      if (!sexpflag)
		break;
	      if (from != stop && c == FETCH_CHAR (from - 1))
		from--;
	      if (mathexit)
		{
		  mathexit = 0;
		  goto open2;
		}
	      mathexit = 1;

	    case Sclose:
	      if (!++depth) goto done2;
	      break;

	    case Sopen:
	    open2:
	      if (!--depth) goto done2;
	      if (depth < min_depth)
		error ("Containing expression ends prematurely");
	      break;

	    case Sendcomment:
	      if (!parse_sexp_ignore_comments)
		break;
1109
#if 0
1110 1111 1112 1113 1114 1115 1116 1117 1118 1119
	      if (code != SYNTAX (c))
		/* For a two-char comment ender, we can assume
		   it does end a comment.  So scan back in a simple way.  */
		{
		  if (from != stop) from--;
		  while (1)
		    {
		      if (SYNTAX (c = FETCH_CHAR (from)) == Scomment
			  && SYNTAX_COMMENT_STYLE (c) == comstyle)
			break;
1120 1121 1122 1123 1124 1125
		      if (from == stop)
			{
			  if (depth == 0)
			    goto done2;
			  goto lose;
			}
1126 1127 1128 1129 1130 1131 1132 1133 1134
		      from--;
		      if (SYNTAX_COMSTART_SECOND (c)
			  && SYNTAX_COMSTART_FIRST (FETCH_CHAR (from))
			  && SYNTAX_COMMENT_STYLE (c) == comstyle
			  && !char_quoted (from))
			break;
		    }
		  break;
		}
1135
#endif /* 0 */
1136

Richard M. Stallman's avatar
Richard M. Stallman committed
1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147
	      /* Look back, counting the parity of string-quotes,
		 and recording the comment-starters seen.
		 When we reach a safe place, assume that's not in a string;
		 then step the main scan to the earliest comment-starter seen
		 an even number of string quotes away from the safe place.

		 OFROM[I] is position of the earliest comment-starter seen
		 which is I+2X quotes from the comment-end.
		 PARITY is current parity of quotes from the comment end.  */
	      {
		int parity = 0;
1148 1149 1150
		char my_stringend = 0;
		int string_lossage = 0;
		int comment_end = from;
1151 1152
		int comstart_pos = 0;
		int comstart_parity = 0;
Richard M. Stallman's avatar
Richard M. Stallman committed
1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167

		/* At beginning of range to scan, we're outside of strings;
		   that determines quote parity to the comment-end.  */
		while (from != stop)
		  {
		    /* Move back and examine a character.  */
		    from--;

		    c = FETCH_CHAR (from);
		    code = SYNTAX (c);

		    /* If this char is the second of a 2-char comment sequence,
		       back up and give the pair the appropriate syntax.  */
		    if (from > stop && SYNTAX_COMEND_SECOND (c)
			&& SYNTAX_COMEND_FIRST (FETCH_CHAR (from - 1)))
1168 1169 1170 1171 1172
		      {
			code = Sendcomment;
			from--;
		      }
			
Richard M. Stallman's avatar
Richard M. Stallman committed
1173
		    else if (from > stop && SYNTAX_COMSTART_SECOND (c)
1174 1175 1176 1177 1178 1179
			     && SYNTAX_COMSTART_FIRST (FETCH_CHAR (from - 1))
			     && comstyle == SYNTAX_COMMENT_STYLE (c))
		      {
			code = Scomment;
			from--;
		      }
Richard M. Stallman's avatar
Richard M. Stallman committed
1180 1181 1182 1183 1184

		    /* Ignore escaped characters.  */
		    if (char_quoted (from))
		      continue;

1185
		    /* Track parity of quotes.  */
Richard M. Stallman's avatar
Richard M. Stallman committed
1186
		    if (code == Sstring)
1187 1188 1189 1190
		      {
			parity ^= 1;
			if (my_stringend == 0)
			  my_stringend = c;
1191
			/* If we have two kinds of string delimiters.
1192 1193 1194 1195
			   There's no way to grok this scanning backwards.  */
			else if (my_stringend != c)
			  string_lossage = 1;
		      }
Richard M. Stallman's avatar
Richard M. Stallman committed
1196 1197 1198 1199

		    /* Record comment-starters according to that
		       quote-parity to the comment-end.  */
		    if (code == Scomment)
1200 1201 1202 1203
		      {
			comstart_parity = parity;
			comstart_pos = from;
		      }
Richard M. Stallman's avatar
Richard M. Stallman committed
1204

1205
		    /* If we find another earlier comment-ender,
1206
		       any comment-starts earlier than that don't count
1207
		       (because they go with the earlier comment-ender).  */
1208 1209
		    if (code == Sendcomment
			&& SYNTAX_COMMENT_STYLE (FETCH_CHAR (from)) == comstyle)
Richard M. Stallman's avatar
Richard M. Stallman committed
1210
		      break;
1211 1212 1213 1214 1215

		    /* Assume a defun-start point is outside of strings.  */
		    if (code == Sopen
			&& (from == stop || FETCH_CHAR (from - 1) == '\n'))
		      break;
Richard M. Stallman's avatar
Richard M. Stallman committed
1216
		  }
1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227

		if (comstart_pos == 0)
		  from = comment_end;
		/* If the earliest comment starter
		   is followed by uniform paired string quotes or none,
		   we know it can't be inside a string
		   since if it were then the comment ender would be inside one.
		   So it does start a comment.  Skip back to it.  */
		else if (comstart_parity == 0 && !string_lossage)
		  from = comstart_pos;
		else
1228 1229 1230 1231 1232 1233 1234
		  {
		    /* We had two kinds of string delimiters mixed up
		       together.  Decode this going forwards.
		       Scan fwd from the previous comment ender
		       to the one in question; this records where we
		       last passed a comment starter.  */
		    struct lisp_parse_state state;
1235
		    scan_sexps_forward (&state, find_defun_start (comment_end),
1236
					comment_end - 1, -10000, 0, Qnil, 0);
1237 1238 1239 1240 1241 1242
		    if (state.incomment)
		      from = state.comstart;
		    else
		      /* We can't grok this as a comment; scan it normally.  */
		      from = comment_end;
		  }
Richard M. Stallman's avatar
Richard M. Stallman committed
1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281
	      }
	      break;

	    case Sstring:
	      stringterm = FETCH_CHAR (from);
	      while (1)
		{
		  if (from == stop) goto lose;
		  if (!char_quoted (from - 1)
		      && stringterm == FETCH_CHAR (from - 1))
		    break;
		  from--;
		}
	      from--;
	      if (!depth && sexpflag) goto done2;
	      break;
	    }
	}

      /* Reached start of buffer.  Error if within object, return nil if between */
      if (depth) goto lose;

      immediate_quit = 0;
      return Qnil;

    done2:
      count++;
    }


  immediate_quit = 0;
  XFASTINT (val) = from;
  return val;

 lose:
  error ("Unbalanced parentheses");
  /* NOTREACHED */
}

1282
static int
Richard M. Stallman's avatar
Richard M. Stallman committed
1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360
char_quoted (pos)
     register int pos;
{
  register enum syntaxcode code;
  register int beg = BEGV;
  register int quoted = 0;

  while (pos > beg
	 && ((code = SYNTAX (FETCH_CHAR (pos - 1))) == Scharquote
	     || code == Sescape))
    pos--, quoted = !quoted;
  return quoted;
}

DEFUN ("scan-lists", Fscan_lists, Sscan_lists, 3, 3, 0,
  "Scan from character number FROM by COUNT lists.\n\
Returns the character number of the position thus found.\n\
\n\
If DEPTH is nonzero, paren depth begins counting from that value,\n\
only places where the depth in parentheses becomes zero\n\
are candidates for stopping; COUNT such places are counted.\n\
Thus, a positive value for DEPTH means go out levels.\n\
\n\
Comments are ignored if `parse-sexp-ignore-comments' is non-nil.\n\
\n\
If the beginning or end of (the accessible part of) the buffer is reached\n\
and the depth is wrong, an error is signaled.\n\
If the depth is right but the count is not used up, nil is returned.")
  (from, count, depth)
     Lisp_Object from, count, depth;
{
  CHECK_NUMBER (from, 0);
  CHECK_NUMBER (count, 1);
  CHECK_NUMBER (depth, 2);

  return scan_lists (XINT (from), XINT (count), XINT (depth), 0);
}

DEFUN ("scan-sexps", Fscan_sexps, Sscan_sexps, 2, 2, 0,
  "Scan from character number FROM by COUNT balanced expressions.\n\
If COUNT is negative, scan backwards.\n\
Returns the character number of the position thus found.\n\
\n\
Comments are ignored if `parse-sexp-ignore-comments' is non-nil.\n\
\n\
If the beginning or end of (the accessible part of) the buffer is reached\n\
in the middle of a parenthetical grouping, an error is signaled.\n\
If the beginning or end is reached between groupings\n\
but before count is used up, nil is returned.")
  (from, count)
     Lisp_Object from, count;
{
  CHECK_NUMBER (from, 0);
  CHECK_NUMBER (count, 1);

  return scan_lists (XINT (from), XINT (count), 0, 1);
}

DEFUN ("backward-prefix-chars", Fbackward_prefix_chars, Sbackward_prefix_chars,
  0, 0, 0,
  "Move point backward over any number of chars with prefix syntax.\n\
This includes chars with \"quote\" or \"prefix\" syntax (' or p).")
  ()
{
  int beg = BEGV;
  int pos = point;

  while (pos > beg && !char_quoted (pos - 1)
	 && (SYNTAX (FETCH_CHAR (pos - 1)) == Squote
	     || SYNTAX_PREFIX (FETCH_CHAR (pos - 1))))
    pos--;

  SET_PT (pos);

  return Qnil;
}

/* Parse forward from FROM to END,
1361 1362
   assuming that FROM has state OLDSTATE (nil means FROM is start of function),
   and return a description of the state of the parse at END.
1363 1364
   If STOPBEFORE is nonzero, stop at the start of an atom.
   If COMMENTSTOP is nonzero, stop at the start of a comment.  */
Richard M. Stallman's avatar
Richard M. Stallman committed
1365

1366
static void
1367 1368
scan_sexps_forward (stateptr, from, end, targetdepth,
		    stopbefore, oldstate, commentstop)
1369
     struct lisp_parse_state *stateptr;
Richard M. Stallman's avatar
Richard M. Stallman committed
1370 1371 1372
     register int from;
     int end, targetdepth, stopbefore;
     Lisp_Object oldstate;
1373
     int commentstop;
Richard M. Stallman's avatar
Richard M. Stallman committed
1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392
{
  struct lisp_parse_state state;

  register enum syntaxcode code;
  struct level { int last, prev; };
  struct level levelstart[100];
  register struct level *curlevel = levelstart;
  struct level *endlevel = levelstart + 100;
  char prev;
  register int depth;	/* Paren depth of current scanning location.
			   level - levelstart equals this except
			   when the depth becomes negative.  */
  int mindepth;		/* Lowest DEPTH value seen.  */
  int start_quoted = 0;		/* Nonzero means starting after a char quote */
  Lisp_Object tem;

  immediate_quit = 1;
  QUIT;

Jim Blandy's avatar
Jim Blandy committed
1393
  if (NILP (oldstate))
Richard M. Stallman's avatar
Richard M. Stallman committed
1394 1395 1396 1397
    {
      depth = 0;
      state.instring = -1;
      state.incomment = 0;
1398
      state.comstyle = 0;	/* comment style a by default */
Richard M. Stallman's avatar
Richard M. Stallman committed
1399 1400 1401 1402
    }
  else
    {
      tem = Fcar (oldstate);
Jim Blandy's avatar
Jim Blandy committed
1403
      if (!NILP (tem))
Richard M. Stallman's avatar
Richard M. Stallman committed
1404 1405 1406 1407 1408 1409 1410 1411
	depth = XINT (tem);
      else
	depth = 0;

      oldstate = Fcdr (oldstate);
      oldstate = Fcdr (oldstate);
      oldstate = Fcdr (oldstate);
      tem = Fcar (oldstate);
Jim Blandy's avatar
Jim Blandy committed
1412
      state.instring = !NILP (tem) ? XINT (tem) : -1;
Richard M. Stallman's avatar
Richard M. Stallman committed
1413 1414 1415

      oldstate = Fcdr (oldstate);
      tem = Fcar (oldstate);
Jim Blandy's avatar
Jim Blandy committed
1416
      state.incomment = !NILP (tem);
Richard M. Stallman's avatar
Richard M. Stallman committed
1417 1418 1419

      oldstate = Fcdr (oldstate);
      tem = Fcar (oldstate);
Jim Blandy's avatar
Jim Blandy committed
1420
      start_quoted = !NILP (tem);
1421 1422 1423 1424 1425 1426 1427

      /* if the eight element of the list is nil, we are in comment
	 style a. if it is non-nil, we are in comment style b */
      oldstate = Fcdr (oldstate);
      oldstate = Fcdr (oldstate);
      tem = Fcar (oldstate);
      state.comstyle = !NILP (tem);
Richard M. Stallman's avatar
Richard M. Stallman committed
1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446
    }
  state.quoted = 0;
  mindepth = depth;

  curlevel->prev = -1;
  curlevel->last = -1;

  /* Enter the loop at a place appropriate for initial state. */

  if (state.incomment) goto startincomment;
  if (state.instring >= 0)
    {
      if (start_quoted) goto startquotedinstring;
      goto startinstring;
    }
  if (start_quoted) goto startquoted;

  while (from < end)
    {
1447
      code = SYNTAX (FETCH_CHAR (from));
Richard M. Stallman's avatar
Richard M. Stallman committed
1448
      from++;
1449 1450 1451 1452 1453
      if (code == Scomment)
	state.comstart = from-1;
      
      else if (from < end && SYNTAX_COMSTART_FIRST (FETCH_CHAR (from - 1))
	       && SYNTAX_COMSTART_SECOND (FETCH_CHAR (from)))
1454 1455 1456 1457 1458 1459
	{
	  /* Record the comment style we have entered so that only
	     the comment-end sequence of the same style actually
	     terminates the comment section.  */
	  code = Scomment;
	  state.comstyle = SYNTAX_COMMENT_STYLE (FETCH_CHAR (from));
1460
	  state.comstart = from-1;
1461 1462 1463
	  from++;
	}

Richard M. Stallman's avatar
Richard M. Stallman committed
1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488
      if (SYNTAX_PREFIX (FETCH_CHAR (from - 1)))
	continue;
#ifdef SWITCH_ENUM_BUG
      switch ((int) code)
#else
      switch (code)
#endif
	{
	case Sescape:
	case Scharquote:
	  if (stopbefore) goto stop;  /* this arg means stop at sexp start */
	  curlevel->last = from - 1;
	startquoted:
	  if (from == end) goto endquoted;
	  from++;
	  goto symstarted;
	  /* treat following character as a word constituent */
	case Sword:
	case Ssymbol:
	  if (stopbefore) goto stop;  /* this arg means stop at sexp start */
	  curlevel->last = from - 1;
	symstarted:
	  while (from < end)
	    {
#ifdef SWITCH_ENUM_BUG
1489
	      switch ((int) SYNTAX (FETCH_CHAR (from)))
Richard M. Stallman's avatar
Richard M. Stallman committed
1490
#else
1491
	      switch (SYNTAX (FETCH_CHAR (from)))
Richard M. Stallman's avatar
Richard M. Stallman committed
1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514
#endif
		{
		case Scharquote:
		case Sescape:
		  from++;
		  if (from == end) goto endquoted;
		  break;
		case Sword:
		case Ssymbol:
		case Squote:
		  break;
		default:
		  goto symdone;
		}
	      from++;
	    }
	symdone:
	  curlevel->prev = curlevel->last;
	  break;

	case Scomment:
	  state.incomment = 1;
	startincomment:
1515 1516
	  if (commentstop)
	    goto done;
Richard M. Stallman's avatar
Richard M. Stallman committed
1517 1518 1519
	  while (1)
	    {
	      if (from == end) goto done;
1520 1521 1522 1523 1524 1525
	      prev = FETCH_CHAR (from);
	      if (SYNTAX (prev) == Sendcomment
		  && SYNTAX_COMMENT_STYLE (prev) == state.comstyle)
		/* Only terminate the comment section if the endcomment
		   of the same style as the start sequence has been
		   encountered.  */
Richard M. Stallman's avatar
Richard M. Stallman committed
1526 1527 1528
		break;
	      from++;
	      if (from < end && SYNTAX_COMEND_FIRST (prev)
1529 1530 1531 1532 1533
		  && SYNTAX_COMEND_SECOND (FETCH_CHAR (from))
		  && SYNTAX_COMMENT_STYLE (prev) == state.comstyle)
		/* Only terminate the comment section if the end-comment
		   sequence of the same style as the start sequence has
		   been encountered.  */
Richard M. Stallman's avatar
Richard M. Stallman committed
1534 1535 1536
		{ from++; break; }
	    }
	  state.incomment = 0;
1537
	  state.comstyle = 0;	/* reset the comment style */
Richard M. Stallman's avatar
Richard M. Stallman committed
1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571
	  break;

	case Sopen:
	  if (stopbefore) goto stop;  /* this arg means stop at sexp start */
	  depth++;
	  /* curlevel++->last ran into compiler bug on Apollo */
	  curlevel->last = from - 1;
	  if (++curlevel == endlevel)
	    error ("Nesting too deep for parser");
	  curlevel->prev = -1;
	  curlevel->last = -1;
	  if (!--targetdepth) goto done;
	  break;

	case Sclose:
	  depth--;
	  if (depth < mindepth)
	    mindepth = depth;
	  if (curlevel != levelstart)
	    curlevel--;
	  curlevel->prev = curlevel->last;
	  if (!++targetdepth) goto done;
	  break;

	case Sstring:
	  if (stopbefore) goto stop;  /* this arg means stop at sexp start */
	  curlevel->last = from - 1;
	  state.instring = FETCH_CHAR (from - 1);
	startinstring:
	  while (1)
	    {
	      if (from >= end) goto done;
	      if (FETCH_CHAR (from) == state.instring) break;
#ifdef SWITCH_ENUM_BUG
1572
	      switch ((int) SYNTAX (FETCH_CHAR (from)))
Richard M. Stallman's avatar
Richard M. Stallman committed
1573
#else
1574
	      switch (SYNTAX (FETCH_CHAR (from)))
Richard M. Stallman's avatar
Richard M. Stallman committed
1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610
#endif
		{
		case Scharquote:
		case Sescape:
		  from++;
		startquotedinstring:
		  if (from >= end) goto endquoted;
		}
	      from++;
	    }
	  state.instring = -1;
	  curlevel->prev = curlevel->last;
	  from++;
	  break;

	case Smath:
	  break;
	}
    }
  goto done;

 stop:   /* Here if stopping before start of sexp. */
  from--;    /* We have just fetched the char that starts it; */
  goto done; /* but return the position before it. */

 endquoted:
  state.quoted = 1;
 done:
  state.depth = depth;
  state.mindepth = mindepth;
  state.thislevelstart = curlevel->prev;
  state.prevlevelstart
    = (curlevel == levelstart) ? -1 : (curlevel - 1)->last;
  state.location = from;
  immediate_quit = 0;

1611
  *stateptr = state;
Richard M. Stallman's avatar
Richard M. Stallman committed
1612 1613 1614 1615 1616 1617
}

/* This comment supplies the doc string for parse-partial-sexp,
   for make-docfile to see.  We cannot put this in the real DEFUN
   due to limits in the Unix cpp.

1618
DEFUN ("parse-partial-sexp", Ffoo, Sfoo, 2, 6, 0,
Richard M. Stallman's avatar
Richard M. Stallman committed
1619 1620 1621 1622 1623
  "Parse Lisp syntax starting at FROM until TO; return status of parse at TO.\n\
Parsing stops at TO or when certain criteria are met;\n\
 point is set to where parsing stops.\n\
If fifth arg STATE is omitted or nil,\n\
 parsing assumes that FROM is the beginning of a function.\n\
1624
Value is a list of eight elements describing final state of parsing:\n\
Richard M. Stallman's avatar
Richard M. Stallman committed
1625 1626 1627 1628
 0. depth in parens.\n\
 1. character address of start of innermost containing list; nil if none.\n\
 2. character address of start of last complete sexp terminated.\n\
 3. non-nil if inside a string.\n\
Richard M. Stallman's avatar
Richard M. Stallman committed
1629
    (it is the character that will terminate the string.)\n\
Richard M. Stallman's avatar
Richard M. Stallman committed
1630 1631 1632 1633
 4. t if inside a comment.\n\
 5. t if following a quote character.\n\
 6. the minimum paren-depth encountered during this scan.\n\
 7. t if in a comment of style `b'.\n\
Richard M. Stallman's avatar
Richard M. Stallman committed
1634 1635 1636 1637
If third arg TARGETDEPTH is non-nil, parsing stops if the depth\n\
in parentheses becomes equal to TARGETDEPTH.\n\
Fourth arg STOPBEFORE non-nil means stop when come to\n\
 any character that starts a sexp.\n\
Richard M. Stallman's avatar
Richard M. Stallman committed
1638
Fifth arg STATE is an eight-list like what this function returns.\n\
Jim Blandy's avatar
Jim Blandy committed
1639
It is used to initialize the state of the parse.  Its second and third
1640 1641 1642
elements are ignored.
Sixth args COMMENTSTOP non-nil means stop at the start of a comment.")
  (from, to, targetdepth, stopbefore, state, commentstop)
Richard M. Stallman's avatar
Richard M. Stallman committed
1643 1644
*/