syntax.c 93 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.
2
   Copyright (C) 1985, 1987, 1993, 1994, 1995, 1997, 1998, 1999, 2002,
3
                 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
Richard M. Stallman's avatar
Richard M. Stallman committed
4 5 6 7 8

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
9
the Free Software Foundation; either version 2, or (at your option)
Richard M. Stallman's avatar
Richard M. Stallman committed
10 11 12 13 14 15 16 17 18
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
Lute Kamstra's avatar
Lute Kamstra committed
19 20
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.  */
Richard M. Stallman's avatar
Richard M. Stallman committed
21 22


23
#include <config.h>
Richard M. Stallman's avatar
Richard M. Stallman committed
24 25 26 27
#include <ctype.h>
#include "lisp.h"
#include "commands.h"
#include "buffer.h"
Karl Heuer's avatar
Karl Heuer committed
28
#include "charset.h"
Stefan Monnier's avatar
Stefan Monnier committed
29
#include "keymap.h"
Richard M. Stallman's avatar
Richard M. Stallman committed
30
#include "regex.h"
31 32 33 34

/* Make syntax table lookup grant data in gl_state.  */
#define SYNTAX_ENTRY_VIA_PROPERTY

Richard M. Stallman's avatar
Richard M. Stallman committed
35
#include "syntax.h"
36 37 38 39 40 41 42 43
#include "intervals.h"

/* We use these constants in place for comment-style and
   string-ender-char to distinguish  comments/strings started by
   comment_fence and string_fence codes.  */

#define ST_COMMENT_STYLE (256 + 1)
#define ST_STRING_STYLE (256 + 2)
Karl Heuer's avatar
Karl Heuer committed
44
#include "category.h"
Richard M. Stallman's avatar
Richard M. Stallman committed
45

46
Lisp_Object Qsyntax_table_p, Qsyntax_table, Qscan_error;
Richard M. Stallman's avatar
Richard M. Stallman committed
47 48

int words_include_escapes;
49
int parse_sexp_lookup_properties;
Richard M. Stallman's avatar
Richard M. Stallman committed
50

51 52 53
/* Nonzero means `scan-sexps' treat all multibyte characters as symbol.  */
int multibyte_syntax_as_symbol;

54 55 56 57 58
/* Used as a temporary in SYNTAX_ENTRY and other macros in syntax.h,
   if not compiled with GCC.  No need to mark it, since it is used
   only very temporarily.  */
Lisp_Object syntax_temp;

59 60 61 62 63 64
/* Non-zero means an open parenthesis in column 0 is always considered
   to be the start of a defun.  Zero means an open parenthesis in
   column 0 has no special meaning.  */

int open_paren_in_column_0_is_defun_start;

65 66 67 68
/* This is the internal form of the parse state used in parse-partial-sexp.  */

struct lisp_parse_state
  {
69 70
    int depth;		/* Depth at end of parsing.  */
    int instring;	/* -1 if not within string, else desired terminator.  */
71
    int incomment;	/* -1 if in unnestable comment else comment nesting */
72
    int comstyle;	/* comment style a=0, or b=1, or ST_COMMENT_STYLE.  */
73 74 75
    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 */
76
    int location;	/* Char number at which parsing stopped.  */
77
    int mindepth;	/* Minimum depth seen while scanning.  */
78
    int comstr_start;	/* Position just after last comment/string starter.  */
79 80
    Lisp_Object levelstarts;	/* Char numbers of starts-of-expression
				   of levels (starting from outermost).  */
81 82
  };

83 84 85
/* 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.
86
   find_start_value_byte is the corresponding byte position.
87 88 89 90 91 92
   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;
93
static int find_start_value_byte;
94 95 96
static struct buffer *find_start_buffer;
static int find_start_begv;
static int find_start_modiff;
97 98 99


static int find_defun_start P_ ((int, int));
100 101
static int back_comment P_ ((EMACS_INT, EMACS_INT, EMACS_INT, int, int,
			     EMACS_INT *, EMACS_INT *));
102
static int char_quoted P_ ((int, int));
Richard M. Stallman's avatar
Richard M. Stallman committed
103
static Lisp_Object skip_chars P_ ((int, int, Lisp_Object, Lisp_Object, int));
104
static Lisp_Object scan_lists P_ ((EMACS_INT, EMACS_INT, EMACS_INT, int));
105 106 107
static void scan_sexps_forward P_ ((struct lisp_parse_state *,
				    int, int, int, int,
				    int, Lisp_Object, int));
Richard M. Stallman's avatar
Richard M. Stallman committed
108
static int in_classes P_ ((int, Lisp_Object));
109 110 111 112 113 114 115 116


struct gl_state_s gl_state;		/* Global state of syntax parser.  */

INTERVAL interval_of ();
#define INTERVALS_AT_ONCE 10		/* 1 + max-number of intervals
					   to scan to property-change.  */

117 118
/* Update gl_state to an appropriate interval which contains CHARPOS.  The
   sign of COUNT give the relative position of CHARPOS wrt the previously
119
   valid interval.  If INIT, only [be]_property fields of gl_state are
120
   valid at start, the rest is filled basing on OBJECT.
121

122
   `gl_state.*_i' are the intervals, and CHARPOS is further in the search
123 124
   direction than the intervals - or in an interval.  We update the
   current syntax-table basing on the property of this interval, and
125
   update the interval to start further than CHARPOS - or be
126
   NULL_INTERVAL.  We also update lim_property to be the next value of
127
   charpos to call this subroutine again - or be before/after the
128 129 130
   start/end of OBJECT.  */

void
131 132
update_syntax_table (charpos, count, init, object)
     int charpos, count, init;
133 134 135
     Lisp_Object object;
{
  Lisp_Object tmp_table;
136
  int cnt = 0, invalidate = 1;
137
  INTERVAL i;
138 139 140

  if (init)
    {
141
      gl_state.old_prop = Qnil;
142 143
      gl_state.start = gl_state.b_property;
      gl_state.stop = gl_state.e_property;
144 145
      i = interval_of (charpos, object);
      gl_state.backward_i = gl_state.forward_i = i;
146 147 148
      invalidate = 0;
      if (NULL_INTERVAL_P (i))
	return;
149
      /* interval_of updates only ->position of the return value, so
150
	 update the parents manually to speed up update_interval.  */
151
      while (!NULL_PARENT (i))
152 153
	{
	  if (AM_RIGHT_CHILD (i))
154
	    INTERVAL_PARENT (i)->position = i->position
155
	      - LEFT_TOTAL_LENGTH (i) + TOTAL_LENGTH (i) /* right end */
156 157
	      - TOTAL_LENGTH (INTERVAL_PARENT (i))
	      + LEFT_TOTAL_LENGTH (INTERVAL_PARENT (i));
158
	  else
159
	    INTERVAL_PARENT (i)->position = i->position - LEFT_TOTAL_LENGTH (i)
160
	      + TOTAL_LENGTH (i);
161
	  i = INTERVAL_PARENT (i);
162 163
	}
      i = gl_state.forward_i;
164
      gl_state.b_property = i->position - gl_state.offset;
165
      gl_state.e_property = INTERVAL_LAST_POS (i) - gl_state.offset;
166 167
      goto update;
    }
168
  i = count > 0 ? gl_state.forward_i : gl_state.backward_i;
169

170
  /* We are guaranteed to be called with CHARPOS either in i,
171
     or further off.  */
172 173
  if (NULL_INTERVAL_P (i))
    error ("Error in syntax_table logic for to-the-end intervals");
174
  else if (charpos < i->position)		/* Move left.  */
175 176
    {
      if (count > 0)
177
	error ("Error in syntax_table logic for intervals <-");
178
      /* Update the interval.  */
179
      i = update_interval (i, charpos);
180
      if (INTERVAL_LAST_POS (i) != gl_state.b_property)
181 182 183
	{
	  invalidate = 0;
	  gl_state.forward_i = i;
184
	  gl_state.e_property = INTERVAL_LAST_POS (i) - gl_state.offset;
185
	}
186
    }
187
  else if (charpos >= INTERVAL_LAST_POS (i)) /* Move right.  */
188 189
    {
      if (count < 0)
190
	error ("Error in syntax_table logic for intervals ->");
191
      /* Update the interval.  */
192
      i = update_interval (i, charpos);
193
      if (i->position != gl_state.e_property)
194 195 196
	{
	  invalidate = 0;
	  gl_state.backward_i = i;
197
	  gl_state.b_property = i->position - gl_state.offset;
198 199 200 201 202 203 204 205
	}
    }

  update:
  tmp_table = textget (i->plist, Qsyntax_table);

  if (invalidate)
    invalidate = !EQ (tmp_table, gl_state.old_prop); /* Need to invalidate? */
Juanma Barranquero's avatar
Juanma Barranquero committed
206

207 208 209
  if (invalidate)		/* Did not get to adjacent interval.  */
    {				/* with the same table => */
				/* invalidate the old range.  */
210 211 212
      if (count > 0)
	{
	  gl_state.backward_i = i;
213 214 215
	  gl_state.b_property = i->position - gl_state.offset;
	}
      else
216
	{
217
	  gl_state.forward_i = i;
218
	  gl_state.e_property = INTERVAL_LAST_POS (i) - gl_state.offset;
219 220
	}
    }
221

222
  if (!EQ (tmp_table, gl_state.old_prop))
223
    {
224 225 226 227 228
      gl_state.current_syntax_table = tmp_table;
      gl_state.old_prop = tmp_table;
      if (EQ (Fsyntax_table_p (tmp_table), Qt))
	{
	  gl_state.use_global = 0;
Juanma Barranquero's avatar
Juanma Barranquero committed
229
	}
230 231 232 233 234
      else if (CONSP (tmp_table))
	{
	  gl_state.use_global = 1;
	  gl_state.global_code = tmp_table;
	}
Juanma Barranquero's avatar
Juanma Barranquero committed
235
      else
236 237 238 239
	{
	  gl_state.use_global = 0;
	  gl_state.current_syntax_table = current_buffer->syntax_table;
	}
240 241 242 243 244 245 246
    }

  while (!NULL_INTERVAL_P (i))
    {
      if (cnt && !EQ (tmp_table, textget (i->plist, Qsyntax_table)))
	{
	  if (count > 0)
247 248 249 250 251 252
	    {
	      gl_state.e_property = i->position - gl_state.offset;
	      gl_state.forward_i = i;
	    }
	  else
	    {
253 254
	      gl_state.b_property
		= i->position + LENGTH (i) - gl_state.offset;
255 256 257
	      gl_state.backward_i = i;
	    }
	  return;
258
	}
Juanma Barranquero's avatar
Juanma Barranquero committed
259
      else if (cnt == INTERVALS_AT_ONCE)
260 261
	{
	  if (count > 0)
262
	    {
263 264 265 266 267 268
	      gl_state.e_property
		= i->position + LENGTH (i) - gl_state.offset
		/* e_property at EOB is not set to ZV but to ZV+1, so that
		   we can do INC(from);UPDATE_SYNTAX_TABLE_FORWARD without
		   having to check eob between the two.  */
		+ (NULL_INTERVAL_P (next_interval (i)) ? 1 : 0);
269 270 271 272 273 274 275 276
	      gl_state.forward_i = i;
	    }
	  else
	    {
	      gl_state.b_property = i->position - gl_state.offset;
	      gl_state.backward_i = i;
	    }
	  return;
277 278 279 280
	}
      cnt++;
      i = count > 0 ? next_interval (i) : previous_interval (i);
    }
281 282 283 284 285
  eassert (NULL_INTERVAL_P (i)); /* This property goes to the end.  */
  if (count > 0)
    gl_state.e_property = gl_state.stop;
  else
    gl_state.b_property = gl_state.start;
286 287
}

288 289 290
/* Returns TRUE if char at CHARPOS is quoted.
   Global syntax-table data should be set up already to be good at CHARPOS
   or after.  On return global syntax data is good for lookup at CHARPOS. */
291 292

static int
293 294
char_quoted (charpos, bytepos)
     register int charpos, bytepos;
295 296 297 298
{
  register enum syntaxcode code;
  register int beg = BEGV;
  register int quoted = 0;
299 300 301
  int orig = charpos;

  DEC_BOTH (charpos, bytepos);
302

303
  while (charpos >= beg)
304
    {
305 306
      int c;

307
      UPDATE_SYNTAX_TABLE_BACKWARD (charpos);
308 309
      c = FETCH_CHAR (bytepos);
      code = SYNTAX (c);
310 311 312 313 314
      if (! (code == Scharquote || code == Sescape))
	break;

      DEC_BOTH (charpos, bytepos);
      quoted = !quoted;
315
    }
316 317

  UPDATE_SYNTAX_TABLE (orig);
318 319
  return quoted;
}
320 321 322 323 324 325 326 327

/* Return the bytepos one character after BYTEPOS.
   We assume that BYTEPOS is not at the end of the buffer.  */

INLINE int
inc_bytepos (bytepos)
     int bytepos;
{
328 329 330
  if (NILP (current_buffer->enable_multibyte_characters))
    return bytepos + 1;

331 332 333 334 335 336 337 338 339 340 341
  INC_POS (bytepos);
  return bytepos;
}

/* Return the bytepos one character before BYTEPOS.
   We assume that BYTEPOS is not at the start of the buffer.  */

INLINE int
dec_bytepos (bytepos)
     int bytepos;
{
342 343 344
  if (NILP (current_buffer->enable_multibyte_characters))
    return bytepos - 1;

345 346 347
  DEC_POS (bytepos);
  return bytepos;
}
348

Richard M. Stallman's avatar
Richard M. Stallman committed
349 350 351 352
/* Return a defun-start position before before POS and not too far before.
   It should be the last one before POS, or nearly the last.

   When open_paren_in_column_0_is_defun_start is nonzero,
353
   only the beginning of the buffer is treated as a defun-start.
Richard M. Stallman's avatar
Richard M. Stallman committed
354 355 356 357

   We record the information about where the scan started
   and what its result was, so that another call in the same area
   can return the same value very quickly.
358 359 360 361

   There is no promise at which position the global syntax data is
   valid on return from the subroutine, so the caller should explicitly
   update the global data.  */
362 363

static int
364 365
find_defun_start (pos, pos_byte)
     int pos, pos_byte;
366
{
367
  int opoint = PT, opoint_byte = PT_BYTE;
368

369 370 371 372 373 374
  if (!open_paren_in_column_0_is_defun_start)
    {
      find_start_value_byte = BEGV_BYTE;
      return BEGV;
    }

375 376 377 378 379 380 381 382 383 384 385 386
  /* 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.  */
387
  scan_newline (pos, pos_byte, BEGV, BEGV_BYTE, -1, 1);
388

389 390 391 392 393
  /* We optimize syntax-table lookup for rare updates.  Thus we accept
     only those `^\s(' which are good in global _and_ text-property
     syntax-tables.  */
  gl_state.current_syntax_table = current_buffer->syntax_table;
  gl_state.use_global = 0;
394
  while (PT > BEGV)
395
    {
396 397
      int c;

398 399
      /* Open-paren at start of line means we may have found our
	 defun-start.  */
400 401
      c = FETCH_CHAR (PT_BYTE);
      if (SYNTAX (c) == Sopen)
402
	{
403
	  SETUP_SYNTAX_TABLE (PT + 1, -1);	/* Try again... */
404 405
	  c = FETCH_CHAR (PT_BYTE);
	  if (SYNTAX (c) == Sopen)
406 407 408 409
	    break;
	  /* Now fallback to the default value.  */
	  gl_state.current_syntax_table = current_buffer->syntax_table;
	  gl_state.use_global = 0;
410
	}
411 412
      /* Move to beg of previous line.  */
      scan_newline (PT, PT_BYTE, BEGV, BEGV_BYTE, -2, 1);
413 414 415
    }

  /* Record what we found, for the next try.  */
416 417
  find_start_value = PT;
  find_start_value_byte = PT_BYTE;
418 419 420 421 422
  find_start_buffer = current_buffer;
  find_start_modiff = MODIFF;
  find_start_begv = BEGV;
  find_start_pos = pos;

423 424
  TEMP_SET_PT_BOTH (opoint, opoint_byte);

425 426 427
  return find_start_value;
}

428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445
/* Return the SYNTAX_COMEND_FIRST of the character before POS, POS_BYTE.  */

static int
prev_char_comend_first (pos, pos_byte)
     int pos, pos_byte;
{
  int c, val;

  DEC_BOTH (pos, pos_byte);
  UPDATE_SYNTAX_TABLE_BACKWARD (pos);
  c = FETCH_CHAR (pos_byte);
  val = SYNTAX_COMEND_FIRST (c);
  UPDATE_SYNTAX_TABLE_FORWARD (pos + 1);
  return val;
}

/* Return the SYNTAX_COMSTART_FIRST of the character before POS, POS_BYTE.  */

446 447 448 449 450
/* static int
 * prev_char_comstart_first (pos, pos_byte)
 *      int pos, pos_byte;
 * {
 *   int c, val;
Juanma Barranquero's avatar
Juanma Barranquero committed
451
 *
452 453 454 455 456 457 458
 *   DEC_BOTH (pos, pos_byte);
 *   UPDATE_SYNTAX_TABLE_BACKWARD (pos);
 *   c = FETCH_CHAR (pos_byte);
 *   val = SYNTAX_COMSTART_FIRST (c);
 *   UPDATE_SYNTAX_TABLE_FORWARD (pos + 1);
 *   return val;
 * } */
459

460 461 462 463 464 465 466 467 468
/* Checks whether charpos FROM is at the end of a comment.
   FROM_BYTE is the bytepos corresponding to FROM.
   Do not move back before STOP.

   Return a positive value if we find a comment ending at FROM/FROM_BYTE;
   return -1 otherwise.

   If successful, store the charpos of the comment's beginning
   into *CHARPOS_PTR, and the bytepos into *BYTEPOS_PTR.
469 470 471

   Global syntax data remains valid for backward search starting at
   the returned value (or at FROM, if the search was not successful).  */
472 473

static int
474
back_comment (from, from_byte, stop, comnested, comstyle, charpos_ptr, bytepos_ptr)
475
     EMACS_INT from, from_byte, stop;
476
     int comnested, comstyle;
477
     EMACS_INT *charpos_ptr, *bytepos_ptr;
478 479 480 481 482 483 484 485 486 487
{
  /* 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.  */
488
  int string_style = -1;	/* Presumed outside of any string. */
489
  int string_lossage = 0;
490
  /* Not a real lossage: indicates that we have passed a matching comment
Juanma Barranquero's avatar
Juanma Barranquero committed
491
     starter plus a non-matching comment-ender, meaning that any matching
492 493 494 495
     comment-starter we might see later could be a false positive (hidden
     inside another comment).
     Test case:  { a (* b } c (* d *) */
  int comment_lossage = 0;
496
  int comment_end = from;
497
  int comment_end_byte = from_byte;
498
  int comstart_pos = 0;
499
  int comstart_byte;
500 501 502 503
  /* Place where the containing defun starts,
     or 0 if we didn't come across it yet.  */
  int defun_start = 0;
  int defun_start_byte = 0;
504
  register enum syntaxcode code;
505
  int nesting = 1;		/* current comment nesting */
506
  int c;
507 508 509 510 511
  int syntax = 0;

  /* FIXME: A }} comment-ender style leads to incorrect behavior
     in the case of {{ c }}} because we ignore the last two chars which are
     assumed to be comment-enders although they aren't.  */
512 513 514 515 516

  /* At beginning of range to scan, we're outside of strings;
     that determines quote parity to the comment-end.  */
  while (from != stop)
    {
517 518
      int temp_byte, prev_syntax;
      int com2start, com2end;
519

520
      /* Move back and examine a character.  */
521
      DEC_BOTH (from, from_byte);
522 523
      UPDATE_SYNTAX_TABLE_BACKWARD (from);

524
      prev_syntax = syntax;
525
      c = FETCH_CHAR (from_byte);
526
      syntax = SYNTAX_WITH_FLAGS (c);
527 528
      code = SYNTAX (c);

529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549
      /* Check for 2-char comment markers.  */
      com2start = (SYNTAX_FLAGS_COMSTART_FIRST (syntax)
		   && SYNTAX_FLAGS_COMSTART_SECOND (prev_syntax)
		   && comstyle == SYNTAX_FLAGS_COMMENT_STYLE (prev_syntax)
		   && (SYNTAX_FLAGS_COMMENT_NESTED (prev_syntax)
		       || SYNTAX_FLAGS_COMMENT_NESTED (syntax)) == comnested);
      com2end = (SYNTAX_FLAGS_COMEND_FIRST (syntax)
		 && SYNTAX_FLAGS_COMEND_SECOND (prev_syntax));

      /* Nasty cases with overlapping 2-char comment markers:
	 - snmp-mode: -- c -- foo -- c --
	              --- c --
		      ------ c --
	 - c-mode:    *||*
		      |* *|* *|
		      |*| |* |*|
		      ///   */

      /* If a 2-char comment sequence partly overlaps with another,
	 we don't try to be clever.  */
      if (from > stop && (com2end || com2start))
550
	{
551 552 553 554 555 556 557 558 559 560 561 562 563 564
	  int next = from, next_byte = from_byte, next_c, next_syntax;
	  DEC_BOTH (next, next_byte);
	  UPDATE_SYNTAX_TABLE_BACKWARD (next);
	  next_c = FETCH_CHAR (next_byte);
	  next_syntax = SYNTAX_WITH_FLAGS (next_c);
	  if (((com2start || comnested)
	       && SYNTAX_FLAGS_COMEND_SECOND (syntax)
	       && SYNTAX_FLAGS_COMEND_FIRST (next_syntax))
	      || ((com2end || comnested)
		  && SYNTAX_FLAGS_COMSTART_SECOND (syntax)
		  && comstyle == SYNTAX_FLAGS_COMMENT_STYLE (syntax)
		  && SYNTAX_FLAGS_COMSTART_FIRST (next_syntax)))
	    goto lossage;
	  /* UPDATE_SYNTAX_TABLE_FORWARD (next + 1); */
565
	}
566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582

      if (com2start && comstart_pos == 0)
	/* We're looking at a comment starter.  But it might be a comment
	   ender as well (see snmp-mode).  The first time we see one, we
	   need to consider it as a comment starter,
	   and the subsequent times as a comment ender.  */
	com2end = 0;

      /* Turn a 2-char comment sequences into the appropriate syntax.  */
      if (com2end)
	code = Sendcomment;
      else if (com2start)
	code = Scomment;
      /* Ignore comment starters of a different style.  */
      else if (code == Scomment
	       && (comstyle != SYNTAX_FLAGS_COMMENT_STYLE (syntax)
		   || SYNTAX_FLAGS_COMMENT_NESTED (syntax) != comnested))
583
	continue;
584

585 586
      /* Ignore escaped characters, except comment-enders.  */
      if (code != Sendcomment && char_quoted (from, from_byte))
587 588
	continue;

589
      switch (code)
590
	{
591 592 593 594 595 596 597 598 599 600 601 602 603 604
	case Sstring_fence:
	case Scomment_fence:
	  c = (code == Sstring_fence ? ST_STRING_STYLE : ST_COMMENT_STYLE);
	case Sstring:
	  /* Track parity of quotes.  */
	  if (string_style == -1)
	    /* Entering a string.  */
	    string_style = c;
	  else if (string_style == c)
	    /* Leaving the string.  */
	    string_style = -1;
	  else
	    /* If we have two kinds of string delimiters.
	       There's no way to grok this scanning backwards.  */
605
	    string_lossage = 1;
606
	  break;
Juanma Barranquero's avatar
Juanma Barranquero committed
607

608 609
	case Scomment:
	  /* We've already checked that it is the relevant comstyle.  */
610
	  if (string_style != -1 || comment_lossage || string_lossage)
611 612 613 614
	    /* There are odd string quotes involved, so let's be careful.
	       Test case in Pascal: " { " a { " } */
	    goto lossage;

615 616 617 618 619 620 621
	  if (!comnested)
	    {
	      /* Record best comment-starter so far.  */
	      comstart_pos = from;
	      comstart_byte = from_byte;
	    }
	  else if (--nesting <= 0)
622 623 624 625 626 627
	    /* nested comments have to be balanced, so we don't need to
	       keep looking for earlier ones.  We use here the same (slightly
	       incorrect) reasoning as below:  since it is followed by uniform
	       paired string quotes, this comment-start has to be outside of
	       strings, else the comment-end itself would be inside a string. */
	    goto done;
628 629
	  break;

630
	case Sendcomment:
631
	  if (SYNTAX_FLAGS_COMMENT_STYLE (syntax) == comstyle
632
	      && ((com2end && SYNTAX_FLAGS_COMMENT_NESTED (prev_syntax))
633
		  || SYNTAX_FLAGS_COMMENT_NESTED (syntax)) == comnested)
634 635 636 637 638 639 640 641 642
	    /* This is the same style of comment ender as ours. */
	    {
	      if (comnested)
		nesting++;
	      else
		/* Anything before that can't count because it would match
		   this comment-ender rather than ours.  */
		from = stop;	/* Break out of the loop.  */
	    }
643 644 645 646 647 648 649 650 651
	  else if (comstart_pos != 0 || c != '\n')
	    /* We're mixing comment styles here, so we'd better be careful.
	       The (comstart_pos != 0 || c != '\n') check is not quite correct
	       (we should just always set comment_lossage), but removing it
	       would imply that any multiline comment in C would go through
	       lossage, which seems overkill.
	       The failure should only happen in the rare cases such as
	         { (* } *)   */
	    comment_lossage = 1;
652
	  break;
653

654 655 656 657 658 659 660 661 662 663 664
	case Sopen:
	  /* Assume a defun-start point is outside of strings.  */
	  if (open_paren_in_column_0_is_defun_start
	      && (from == stop
		  || (temp_byte = dec_bytepos (from_byte),
		      FETCH_CHAR (temp_byte) == '\n')))
	    {
	      defun_start = from;
	      defun_start_byte = from_byte;
	      from = stop;	/* Break out of the loop.  */
	    }
665
	  break;
666 667

	default:
668
	  break;
669
	}
670 671 672 673 674
    }

  if (comstart_pos == 0)
    {
      from = comment_end;
675
      from_byte = comment_end_byte;
676 677
      UPDATE_SYNTAX_TABLE_FORWARD (comment_end - 1);
    }
678 679 680
  /* If comstart_pos is set and we get here (ie. didn't jump to `lossage'
     or `done'), then we've found the beginning of the non-nested comment.  */
  else if (1)	/* !comnested */
681 682
    {
      from = comstart_pos;
683
      from_byte = comstart_byte;
684
      UPDATE_SYNTAX_TABLE_FORWARD (from - 1);
685 686 687
    }
  else
    {
688 689
      struct lisp_parse_state state;
    lossage:
690 691
      /* We had two kinds of string delimiters mixed up
	 together.  Decode this going forwards.
692
	 Scan fwd from a known safe place (beginning-of-defun)
693 694
	 to the one in question; this records where we
	 last passed a comment starter.  */
695 696 697 698 699 700
      /* If we did not already find the defun start, find it now.  */
      if (defun_start == 0)
	{
	  defun_start = find_defun_start (comment_end, comment_end_byte);
	  defun_start_byte = find_start_value_byte;
	}
701
      do
702
	{
703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724
	  scan_sexps_forward (&state,
			      defun_start, defun_start_byte,
			      comment_end, -10000, 0, Qnil, 0);
	  defun_start = comment_end;
	  if (state.incomment == (comnested ? 1 : -1)
	      && state.comstyle == comstyle)
	    from = state.comstr_start;
	  else
	    {
	      from = comment_end;
	      if (state.incomment)
		/* If comment_end is inside some other comment, maybe ours
		   is nested, so we need to try again from within the
		   surrounding comment.  Example: { a (* " *)  */
		{
		  /* FIXME: We should advance by one or two chars. */
		  defun_start = state.comstr_start + 2;
		  defun_start_byte = CHAR_TO_BYTE (defun_start);
		}
	    }
	} while (defun_start < comment_end);

725
      from_byte = CHAR_TO_BYTE (from);
726 727
      UPDATE_SYNTAX_TABLE_FORWARD (from - 1);
    }
Juanma Barranquero's avatar
Juanma Barranquero committed
728

729
 done:
730 731 732
  *charpos_ptr = from;
  *bytepos_ptr = from_byte;

733
  return (from == comment_end) ? -1 : from;
734 735
}

Richard M. Stallman's avatar
Richard M. Stallman committed
736
DEFUN ("syntax-table-p", Fsyntax_table_p, Ssyntax_table_p, 1, 1, 0,
737 738 739
       doc: /* Return t if OBJECT is a syntax table.
Currently, any char-table counts as a syntax table.  */)
     (object)
740
     Lisp_Object object;
Richard M. Stallman's avatar
Richard M. Stallman committed
741
{
742
  if (CHAR_TABLE_P (object)
743
      && EQ (XCHAR_TABLE (object)->purpose, Qsyntax_table))
Richard M. Stallman's avatar
Richard M. Stallman committed
744 745 746 747
    return Qt;
  return Qnil;
}

748
static void
Richard M. Stallman's avatar
Richard M. Stallman committed
749 750 751
check_syntax_table (obj)
     Lisp_Object obj;
{
752 753
  CHECK_TYPE (CHAR_TABLE_P (obj) && EQ (XCHAR_TABLE (obj)->purpose, Qsyntax_table),
	      Qsyntax_table_p, obj);
Juanma Barranquero's avatar
Juanma Barranquero committed
754
}
Richard M. Stallman's avatar
Richard M. Stallman committed
755 756

DEFUN ("syntax-table", Fsyntax_table, Ssyntax_table, 0, 0, 0,
757 758 759
       doc: /* Return the current syntax table.
This is the one specified by the current buffer.  */)
     ()
Richard M. Stallman's avatar
Richard M. Stallman committed
760 761 762 763 764 765
{
  return current_buffer->syntax_table;
}

DEFUN ("standard-syntax-table", Fstandard_syntax_table,
   Sstandard_syntax_table, 0, 0, 0,
766 767 768
       doc: /* Return the standard syntax table.
This is the one used for new buffers.  */)
     ()
Richard M. Stallman's avatar
Richard M. Stallman committed
769 770 771 772 773
{
  return Vstandard_syntax_table;
}

DEFUN ("copy-syntax-table", Fcopy_syntax_table, Scopy_syntax_table, 0, 1, 0,
774 775 776
       doc: /* Construct a new syntax table and return it.
It is a copy of the TABLE, which defaults to the standard syntax table.  */)
     (table)
Richard M. Stallman's avatar
Richard M. Stallman committed
777 778
     Lisp_Object table;
{
779 780
  Lisp_Object copy;

Jim Blandy's avatar
Jim Blandy committed
781
  if (!NILP (table))
782 783 784 785 786
    check_syntax_table (table);
  else
    table = Vstandard_syntax_table;

  copy = Fcopy_sequence (table);
787 788 789 790 791 792 793 794 795 796

  /* Only the standard syntax table should have a default element.
     Other syntax tables should inherit from parents instead.  */
  XCHAR_TABLE (copy)->defalt = Qnil;

  /* Copied syntax tables should all have parents.
     If we copied one with no parent, such as the standard syntax table,
     use the standard syntax table as the copy's parent.  */
  if (NILP (XCHAR_TABLE (copy)->parent))
    Fset_char_table_parent (copy, Vstandard_syntax_table);
797
  return copy;
Richard M. Stallman's avatar
Richard M. Stallman committed
798 799 800
}

DEFUN ("set-syntax-table", Fset_syntax_table, Sset_syntax_table, 1, 1, 0,
801 802 803
       doc: /* Select a new syntax table for the current buffer.
One argument, a syntax table.  */)
     (table)
Richard M. Stallman's avatar
Richard M. Stallman committed
804 805
     Lisp_Object table;
{
806
  int idx;
807
  check_syntax_table (table);
Richard M. Stallman's avatar
Richard M. Stallman committed
808 809
  current_buffer->syntax_table = table;
  /* Indicate that this buffer now has a specified syntax table.  */
Gerd Moellmann's avatar
Gerd Moellmann committed
810 811
  idx = PER_BUFFER_VAR_IDX (syntax_table);
  SET_PER_BUFFER_VALUE_P (current_buffer, idx, 1);
Richard M. Stallman's avatar
Richard M. Stallman committed
812 813 814 815 816
  return table;
}

/* Convert a letter which signifies a syntax code
 into the code it signifies.
817
 This is used by modify-syntax-entry, and other things.  */
Richard M. Stallman's avatar
Richard M. Stallman committed
818 819 820 821 822 823

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,
824
    (char) Swhitespace, (char) Scomment_fence, (char) Sstring, 0377,
Richard M. Stallman's avatar
Richard M. Stallman committed
825 826 827 828 829 830
        (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,
831
    (char) Sinherit, 0377, 0377, 0377, 0377, 0377, 0377, 0377,   /* @, A ... */
Richard M. Stallman's avatar
Richard M. Stallman committed
832 833 834 835 836 837
    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,
838
    0377, 0377, 0377, 0377, (char) Sstring_fence, 0377, 0377, 0377
Richard M. Stallman's avatar
Richard M. Stallman committed
839 840
  };

841
/* Indexed by syntax code, give the letter that describes it.  */
Richard M. Stallman's avatar
Richard M. Stallman committed
842

843
char syntax_code_spec[16] =
Richard M. Stallman's avatar
Richard M. Stallman committed
844
  {
845 846
    ' ', '.', 'w', '_', '(', ')', '\'', '\"', '$', '\\', '/', '<', '>', '@',
    '!', '|'
Richard M. Stallman's avatar
Richard M. Stallman committed
847
  };
Karl Heuer's avatar
Karl Heuer committed
848 849 850 851 852 853 854 855

/* Indexed by syntax code, give the object (cons of syntax code and
   nil) to be stored in syntax table.  Since these objects can be
   shared among syntax tables, we generate them in advance.  By
   sharing objects, the function `describe-syntax' can give a more
   compact listing.  */
static Lisp_Object Vsyntax_code_object;

Richard M. Stallman's avatar
Richard M. Stallman committed
856

857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879
/* Look up the value for CHARACTER in syntax table TABLE's parent
   and its parents.  SYNTAX_ENTRY calls this, when TABLE itself has nil
   for CHARACTER.  It's actually used only when not compiled with GCC.  */

Lisp_Object
syntax_parent_lookup (table, character)
     Lisp_Object table;
     int character;
{
  Lisp_Object value;

  while (1)
    {
      table = XCHAR_TABLE (table)->parent;
      if (NILP (table))
	return Qnil;

      value = XCHAR_TABLE (table)->contents[character];
      if (!NILP (value))
	return value;
    }
}

Richard M. Stallman's avatar
Richard M. Stallman committed
880
DEFUN ("char-syntax", Fchar_syntax, Schar_syntax, 1, 1, 0,
881 882 883 884 885 886
       doc: /* Return the syntax code of CHARACTER, described by a character.
For example, if CHARACTER is a word constituent,
the character `w' is returned.
The characters that correspond to various syntax codes
are listed in the documentation of `modify-syntax-entry'.  */)
     (character)
887
     Lisp_Object character;
Richard M. Stallman's avatar
Richard M. Stallman committed
888
{
889
  int char_int;
890 891 892
  gl_state.current_syntax_table = current_buffer->syntax_table;

  gl_state.use_global = 0;
893
  CHECK_NUMBER (character);
894
  char_int = XINT (character);
895
  return make_number (syntax_code_spec[(int) SYNTAX (char_int)]);
896 897 898
}

DEFUN ("matching-paren", Fmatching_paren, Smatching_paren, 1, 1, 0,
899 900
       doc: /* Return the matching parenthesis of CHARACTER, or nil if none.  */)
     (character)
901
     Lisp_Object character;
902
{
903
  int char_int, code;
904 905
  gl_state.current_syntax_table = current_buffer->syntax_table;
  gl_state.use_global = 0;
906
  CHECK_NUMBER (character);
907
  char_int = XINT (character);
908
  code = SYNTAX (char_int);
909
  if (code == Sopen || code == Sclose)
910
    return SYNTAX_MATCH (char_int);
911
  return Qnil;
Richard M. Stallman's avatar
Richard M. Stallman committed
912 913
}

914
DEFUN ("string-to-syntax", Fstring_to_syntax, Sstring_to_syntax, 1, 1, 0,
915 916 917
       doc: /* Convert a syntax specification STRING into syntax cell form.
STRING should be a string as it is allowed as argument of
`modify-syntax-entry'.  Value is the equivalent cons cell
918
\(CODE . MATCHING-CHAR) that can be used as value of a `syntax-table'
919 920
text property.  */)
     (string)
921
     Lisp_Object string;
Richard M. Stallman's avatar
Richard M. Stallman committed
922
{
923
  register const unsigned char *p;
Richard M. Stallman's avatar
Richard M. Stallman committed
924
  register enum syntaxcode code;
925
  int val;
926
  Lisp_Object match;
Richard M. Stallman's avatar
Richard M. Stallman committed
927

928
  CHECK_STRING (string);
Richard M. Stallman's avatar
Richard M. Stallman committed
929

930
  p = SDATA (string);
Richard M. Stallman's avatar
Richard M. Stallman committed
931 932
  code = (enum syntaxcode) syntax_spec_code[*p++];
  if (((int) code & 0377) == 0377)
933
    error ("Invalid syntax description letter: %c", p[-1]);
Richard M. Stallman's avatar
Richard M. Stallman committed
934

935
  if (code == Sinherit)
936
    return Qnil;
937 938

  if (*p)
939
    {
Karl Heuer's avatar
Karl Heuer committed
940
      int len;
941
      int character = (STRING_CHAR_AND_LENGTH
942
		       (p, SBYTES (string) - 1, len));
Karl Heuer's avatar
Karl Heuer committed
943
      XSETINT (match, character);
944 945
      if (XFASTINT (match) == ' ')
	match = Qnil;
Karl Heuer's avatar
Karl Heuer committed
946
      p += len;
947 948
    }
  else
949
    match = Qnil;
Richard M. Stallman's avatar
Richard M. Stallman committed
950

951
  val = (int) code;
Richard M. Stallman's avatar
Richard M. Stallman committed
952 953 954 955
  while (*p)
    switch (*p++)
      {
      case '1':
956
	val |= 1 << 16;
Richard M. Stallman's avatar
Richard M. Stallman committed
957 958 959
	break;

      case '2':
960
	val |= 1 << 17;
Richard M. Stallman's avatar
Richard M. Stallman committed
961 962 963
	break;

      case '3':
964
	val |= 1 << 18;
Richard M. Stallman's avatar
Richard M. Stallman committed
965 966 967
	break;

      case '4':
968
	val |= 1 << 19;
Richard M. Stallman's avatar
Richard M. Stallman committed
969 970 971
	break;

      case 'p':
972
	val |= 1 << 20;
Richard M. Stallman's avatar
Richard M. Stallman committed
973
	break;
974 975

      case 'b':
976
	val |= 1 << 21;
977
	break;
978 979 980 981

      case 'n':
	val |= 1 << 22;
	break;
Richard M. Stallman's avatar
Richard M. Stallman committed
982
      }
Juanma Barranquero's avatar
Juanma Barranquero committed
983

Karl Heuer's avatar
Karl Heuer committed
984
  if (val < XVECTOR (Vsyntax_code_object)->size && NILP (match))
985
    return XVECTOR (Vsyntax_code_object)->contents[val];
Karl Heuer's avatar
Karl Heuer committed
986 987
  else
    /* Since we can't use a shared object, let's make a new one.  */
988 989 990
    return Fcons (make_number (val), match);
}

991
/* I really don't know why this is interactive
Stefan Monnier's avatar
Stefan Monnier committed
992
   help-form should at least be made useful whilst reading the second arg.  */
Juanma Barranquero's avatar
Juanma Barranquero committed
993
DEFUN ("modify-syntax-entry", Fmodify_syntax_entry, Smodify_syntax_entry, 2, 3,
994
  "cSet syntax for character: \nsSet syntax for %s to: ",
995
       doc: /* Set syntax for character CHAR according to string NEWENTRY.
996
The syntax is changed only for table SYNTAX-TABLE, which defaults to
997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013
 the current buffer's syntax table.
The first character of NEWENTRY should be one of the following:
  Space or -  whitespace syntax.    w   word constituent.
  _           symbol constituent.   .   punctuation.
  (           open-parenthesis.     )   close-parenthesis.
  "           string quote.         \\   escape.
  $           paired delimiter.     '   expression quote or prefix operator.
  <           comment starter.      >   comment ender.
  /           character-quote.      @   inherit from `standard-syntax-table'.
  |           generic string fence. !   generic comment fence.

Only single-character comment start and end sequences are represented thus.
Two-character sequences are represented as described below.
The second character of NEWENTRY is the matching parenthesis,
 used only if the first character is `(' or `)'.
Any additional characters are flags.
Defined flags are the characters 1, 2, 3, 4, b, p, and n.
Pavel Janík's avatar<