1 /* Routines to compute the current syntactic context, for font-lock mode.
2 Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
3 Copyright (C) 1995 Sun Microsystems, Inc.
5 This file is part of XEmacs.
7 XEmacs is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by the
9 Free Software Foundation; either version 2, or (at your option) any
12 XEmacs is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with XEmacs; see the file COPYING. If not, write to
19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* Synched up with: Not in FSF. */
24 /* This code computes the syntactic context of the current point, that is,
25 whether point is within a comment, a string, what have you. It does
26 this by picking a point "known" to be outside of any syntactic constructs
27 and moving forward, examining the syntax of each character.
29 Two caches are used: one caches the last point computed, and the other
30 caches the last point at the beginning of a line. This makes there
31 be little penalty for moving left-to-right on a line a character at a
32 time; makes starting over on a line be cheap; and makes random-accessing
33 within a line relatively cheap.
35 When we move to a different line farther down in the file (but within the
36 current top-level form) we simply continue computing forward. If we move
37 backward more than a line, or move beyond the end of the current tlf, or
38 switch buffers, then we call `beginning-of-defun' and start over from
41 #### We should really rewrite this to keep extents over the buffer
42 that hold the current syntactic information. This would be a big win.
43 This way there would be no guessing or incorrect results.
54 Lisp_Object Qblock_comment;
55 Lisp_Object Qbeginning_of_defun;
57 enum syntactic_context
65 enum block_comment_context
82 Bufpos start_point; /* beginning of defun */
83 Bufpos cur_point; /* cache location */
84 Bufpos end_point; /* end of defun */
85 struct buffer *buffer; /* does this need to be staticpro'd? */
86 enum syntactic_context context; /* single-char-syntax state */
87 enum block_comment_context ccontext; /* block-comment state */
88 enum comment_style style; /* which comment group */
89 Emchar scontext; /* active string delimiter */
90 int depth; /* depth in parens */
91 int backslash_p; /* just read a backslash */
92 int needs_its_head_reexamined; /* we're apparently outside of
93 a top level form, and far away
94 from it. This is a bad situation
95 because it will lead to constant
96 slowness as we keep going way
97 back to that form and moving
98 forward again. In this case,
99 we try to compute a "pseudo-
100 top-level-form" where the
101 depth is 0 and the context
102 is none at both ends. */
105 /* We have two caches; one for the current point and one for
106 the beginning of line. We used to rely on the caller to
107 tell us when to invalidate them, but now we do it ourselves;
108 it lets us be smarter. */
110 static struct context_cache context_cache;
112 static struct context_cache bol_context_cache;
116 #define reset_context_cache(cc) memset (cc, 0, sizeof (struct context_cache))
118 /* This function is called from signal_after_change() to tell us when
119 textual changes are made so we can flush our caches when necessary.
121 We make the following somewhat heuristic assumptions:
123 (remember that current_point is always >= start_point, but may be
124 less than or greater than end_point (we might not be inside any
127 1) Textual changes before the beginning of the current top-level form
128 don't affect anything; all we need to do is offset the caches
130 2) Textual changes right at the beginning of the current
131 top-level form messes things up and requires that we flush
133 3) Textual changes after the beginning of the current top-level form
134 and before one or both or the caches invalidates the corresponding
136 4) Textual changes after the caches and before the end of the
137 current top-level form don't affect anything; all we need to do is
138 offset the caches appropriately.
139 5) Textual changes right at the end of the current top-level form
140 necessitate recomputing that end value.
141 6) Textual changes after the end of the current top-level form
146 font_lock_maybe_update_syntactic_caches (struct buffer *buf, Bufpos start,
147 Bufpos orig_end, Bufpos new_end)
149 /* Note: either both context_cache and bol_context_cache are valid and
150 point to the same buffer, or both are invalid. If we have to
151 invalidate just context_cache, we recopy it from bol_context_cache.
153 if (context_cache.buffer != buf)
154 /* caches don't apply */
156 /* NOTE: The order of the if statements below is important. If you
157 change them around unthinkingly, you will probably break something. */
158 if (orig_end <= context_cache.start_point - 1)
160 /* case 1: before the beginning of the current top-level form */
161 Charcount diff = new_end - orig_end;
163 stderr_out ("font-lock; Case 1\n");
164 context_cache.start_point += diff;
165 context_cache.cur_point += diff;
166 context_cache.end_point += diff;
167 bol_context_cache.start_point += diff;
168 bol_context_cache.cur_point += diff;
169 bol_context_cache.end_point += diff;
171 else if (start <= context_cache.start_point)
174 stderr_out ("font-lock; Case 2\n");
175 /* case 2: right at the current top-level form (paren that starts
176 top level form got deleted or moved away from the newline it
178 reset_context_cache (&context_cache);
179 reset_context_cache (&bol_context_cache);
181 /* OK, now we know that the start is after the beginning of the
182 current top-level form. */
183 else if (start < bol_context_cache.cur_point)
186 stderr_out ("font-lock; Case 3 (1)\n");
187 /* case 3: after the beginning of the current top-level form
188 and before both of the caches */
189 reset_context_cache (&context_cache);
190 reset_context_cache (&bol_context_cache);
192 else if (start < context_cache.cur_point)
195 stderr_out ("font-lock; Case 3 (2)\n");
196 /* case 3: but only need to invalidate one cache */
197 context_cache = bol_context_cache;
199 /* OK, now we know that the start is after the caches. */
200 else if (start >= context_cache.end_point)
203 stderr_out ("font-lock; Case 6\n");
204 /* case 6: after the end of the current top-level form
205 and after the caches. */
207 else if (orig_end <= context_cache.end_point - 2)
209 /* case 4: after the caches and before the end of the
210 current top-level form */
211 Charcount diff = new_end - orig_end;
213 stderr_out ("font-lock; Case 4\n");
214 context_cache.end_point += diff;
215 bol_context_cache.end_point += diff;
220 stderr_out ("font-lock; Case 5\n");
221 /* case 5: right at the end of the current top-level form */
222 context_cache.end_point = context_cache.start_point - 1;
223 bol_context_cache.end_point = context_cache.start_point - 1;
227 /* This function is called from Fkill_buffer(). */
230 font_lock_buffer_was_killed (struct buffer *buf)
232 if (context_cache.buffer == buf)
234 reset_context_cache (&context_cache);
235 reset_context_cache (&bol_context_cache);
240 beginning_of_defun (struct buffer *buf, Bufpos pt)
242 /* This function can GC */
243 Bufpos opt = BUF_PT (buf);
244 if (pt == BUF_BEGV (buf))
246 BUF_SET_PT (buf, pt);
247 /* There used to be some kludginess to call c++-beginning-of-defun
248 if we're in C++ mode. There's no point in this any more;
249 we're using cc-mode. If you really want to get the old c++
250 mode working, fix it rather than the C code. */
251 call0_in_buffer (buf, Qbeginning_of_defun);
253 BUF_SET_PT (buf, opt);
258 end_of_defun (struct buffer *buf, Bufpos pt)
260 Lisp_Object retval = scan_lists (buf, pt, 1, 0, 0, 1);
264 return XINT (retval);
267 /* Set up context_cache for attempting to determine the syntactic context
268 in buffer BUF at point PT. */
271 setup_context_cache (struct buffer *buf, Bufpos pt)
273 int recomputed_start_point = 0;
274 /* This function can GC */
275 if (context_cache.buffer != buf || pt < context_cache.start_point)
279 stderr_out ("reset context cache\n");
280 /* OK, completely invalid. */
281 reset_context_cache (&context_cache);
282 reset_context_cache (&bol_context_cache);
284 if (!context_cache.buffer)
286 /* Need to recompute the start point. */
288 stderr_out ("recompute start\n");
289 context_cache.start_point = beginning_of_defun (buf, pt);
290 recomputed_start_point = 1;
291 bol_context_cache.start_point = context_cache.start_point;
292 bol_context_cache.buffer = context_cache.buffer = buf;
294 if (context_cache.end_point < context_cache.start_point)
296 /* Need to recompute the end point. */
298 stderr_out ("recompute end\n");
299 context_cache.end_point = end_of_defun (buf, context_cache.start_point);
300 bol_context_cache.end_point = context_cache.end_point;
302 if (bol_context_cache.cur_point == 0 ||
303 pt < bol_context_cache.cur_point)
306 stderr_out ("reset to start\n");
307 if (pt > context_cache.end_point
308 /* 3000 is some arbitrary delta but seems reasonable;
309 about the size of a reasonable function */
310 && pt - context_cache.end_point > 3000)
311 /* If we're far past the end of the top level form,
312 don't trust it; recompute it. */
314 /* But don't get in an infinite loop doing this.
315 If we're really far past the end of the top level
316 form, try to compute a pseudo-top-level form. */
317 if (recomputed_start_point)
318 context_cache.needs_its_head_reexamined = 1;
320 /* force recomputation */
323 /* Go to the nearest end of the top-level form that's before
325 if (pt > context_cache.end_point)
326 pt = context_cache.end_point;
328 pt = context_cache.start_point;
329 /* Reset current point to start of buffer. */
330 context_cache.cur_point = pt;
331 context_cache.context = context_none;
332 context_cache.ccontext = ccontext_none;
333 context_cache.style = comment_style_none;
334 context_cache.scontext = '\000';
335 context_cache.depth = 0;
336 context_cache.backslash_p = ((pt > 1) &&
337 (BUF_FETCH_CHAR (buf, pt - 1) == '\\'));
338 /* Note that the BOL context cache may not be at the beginning
339 of the line, but that should be OK, nobody's checking. */
340 bol_context_cache = context_cache;
343 else if (pt < context_cache.cur_point)
346 stderr_out ("reset to bol\n");
347 /* bol cache is OK but current_cache is not. */
348 context_cache = bol_context_cache;
351 else if (pt <= context_cache.end_point)
354 stderr_out ("everything is OK\n");
355 /* in same top-level form. */
359 /* OK, we're past the end of the top-level form. */
360 Bufpos maxpt = max (context_cache.end_point, context_cache.cur_point);
366 stderr_out ("past end\n");
371 /* This appears to cause huge slowdowns in files which have no
374 In any case, it's not really necessary that we know for
375 sure the top-level form we're in; if we're in a form
376 but the form we have recorded is the previous one,
379 scan_buffer (buf, '\n', maxpt, pt, 1, &shortage, 1);
381 /* If there was a newline in the region past the known universe,
382 we might be inside another top-level form, so start over.
383 Otherwise, we're outside of any top-level forms and we know
384 the one directly before us, so it's OK. */
390 #define SYNTAX_START_STYLE(table, c1, c2) \
391 (SYNTAX_STYLES_MATCH_START_P (table, c1, c2, SYNTAX_COMMENT_STYLE_A) ? \
393 SYNTAX_STYLES_MATCH_START_P (table, c1, c2, SYNTAX_COMMENT_STYLE_B) ? \
397 #define SYNTAX_END_STYLE(table, c1, c2) \
398 (SYNTAX_STYLES_MATCH_END_P (table, c1, c2, SYNTAX_COMMENT_STYLE_A) ? \
400 SYNTAX_STYLES_MATCH_END_P (table, c1, c2, SYNTAX_COMMENT_STYLE_B) ? \
404 #define SINGLE_SYNTAX_STYLE(table, c) \
405 (SYNTAX_STYLES_MATCH_1CHAR_P (table, c, SYNTAX_COMMENT_STYLE_A) ? \
407 SYNTAX_STYLES_MATCH_1CHAR_P (table, c, SYNTAX_COMMENT_STYLE_B) ? \
411 /* Set up context_cache for position PT in BUF. */
414 find_context (struct buffer *buf, Bufpos pt)
416 /* This function can GC */
417 Lisp_Char_Table *mirrortab = XCHAR_TABLE (buf->mirror_syntax_table);
418 Lisp_Object syntaxtab = buf->syntax_table;
421 setup_context_cache (buf, pt);
422 pt = context_cache.cur_point;
424 if (pt > BUF_BEGV (buf))
425 c = BUF_FETCH_CHAR (buf, pt - 1);
427 c = '\n'; /* to get bol_context_cache at point-min */
429 for (; pt < target; pt++, context_cache.cur_point = pt)
431 if (context_cache.needs_its_head_reexamined)
433 if (context_cache.depth == 0
434 && context_cache.context == context_none)
436 /* We've found an anchor spot.
437 Try to put the start of defun within 6000 chars of
438 the target, and the end of defun as close as possible.
439 6000 is also arbitrary but tries to strike a balance
440 between two conflicting pulls when dealing with a
441 file that has lots of stuff sitting outside of a top-
444 a) If you move past the start of defun, you will
445 have to recompute defun, which in this case
446 means that start of defun goes all the way back
447 to the beginning of the file; so you want
448 to set start of defun a ways back from the
450 b) If you move a line backwards but within start of
451 defun, you have to move back to start of defun;
452 so you don't want start of defun too far from
455 if (target - context_cache.start_point > 6000)
456 context_cache.start_point = pt;
457 context_cache.end_point = pt;
458 bol_context_cache = context_cache;
463 c = BUF_FETCH_CHAR (buf, pt);
466 bol_context_cache = context_cache;
468 if (context_cache.backslash_p)
470 context_cache.backslash_p = 0;
474 switch (SYNTAX (mirrortab, c))
477 context_cache.backslash_p = 1;
481 if (context_cache.context == context_none)
482 context_cache.depth++;
486 if (context_cache.context == context_none)
487 context_cache.depth--;
491 if (context_cache.context == context_none)
493 context_cache.context = context_comment;
494 context_cache.ccontext = ccontext_none;
495 context_cache.style = SINGLE_SYNTAX_STYLE (mirrortab, c);
496 if (context_cache.style == comment_style_none) abort ();
501 if (context_cache.style != SINGLE_SYNTAX_STYLE (mirrortab, c))
503 else if (context_cache.context == context_comment)
505 context_cache.context = context_none;
506 context_cache.style = comment_style_none;
508 else if (context_cache.context == context_block_comment &&
509 (context_cache.ccontext == ccontext_start2 ||
510 context_cache.ccontext == ccontext_end1))
512 context_cache.context = context_none;
513 context_cache.ccontext = ccontext_none;
514 context_cache.style = comment_style_none;
520 if (context_cache.context == context_string &&
521 context_cache.scontext == c)
523 context_cache.context = context_none;
524 context_cache.scontext = '\000';
526 else if (context_cache.context == context_none)
528 Lisp_Object stringtermobj = syntax_match (syntaxtab, c);
531 if (CHARP (stringtermobj))
532 stringterm = XCHAR (stringtermobj);
535 context_cache.context = context_string;
536 context_cache.scontext = stringterm;
537 context_cache.ccontext = ccontext_none;
545 /* That takes care of the characters with manifest syntax.
546 Now we've got to hack multi-char sequences that start
547 and end block comments.
549 if ((SYNTAX_COMMENT_BITS (mirrortab, c) &
550 SYNTAX_SECOND_CHAR_START) &&
551 context_cache.context == context_none &&
552 context_cache.ccontext == ccontext_start1 &&
553 SYNTAX_START_P (mirrortab, prev_c, c) /* the two chars match */
556 context_cache.ccontext = ccontext_start2;
557 context_cache.style = SYNTAX_START_STYLE (mirrortab, prev_c, c);
558 if (context_cache.style == comment_style_none) abort ();
560 else if ((SYNTAX_COMMENT_BITS (mirrortab, c) &
561 SYNTAX_FIRST_CHAR_START) &&
562 context_cache.context == context_none &&
563 (context_cache.ccontext == ccontext_none ||
564 context_cache.ccontext == ccontext_start1))
566 context_cache.ccontext = ccontext_start1;
567 context_cache.style = comment_style_none; /* should be this already*/
569 else if ((SYNTAX_COMMENT_BITS (mirrortab, c) &
570 SYNTAX_SECOND_CHAR_END) &&
571 context_cache.context == context_block_comment &&
572 context_cache.ccontext == ccontext_end1 &&
573 SYNTAX_END_P (mirrortab, prev_c, c) &&
574 /* the two chars match */
575 context_cache.style ==
576 SYNTAX_END_STYLE (mirrortab, prev_c, c)
579 context_cache.context = context_none;
580 context_cache.ccontext = ccontext_none;
581 context_cache.style = comment_style_none;
583 else if ((SYNTAX_COMMENT_BITS (mirrortab, c) &
584 SYNTAX_FIRST_CHAR_END) &&
585 context_cache.context == context_block_comment &&
586 (context_cache.style ==
587 SYNTAX_END_STYLE (mirrortab, c,
588 BUF_FETCH_CHAR (buf, pt+1))) &&
589 (context_cache.ccontext == ccontext_start2 ||
590 context_cache.ccontext == ccontext_end1))
591 /* #### is it right to check for end1 here?? */
593 if (context_cache.style == comment_style_none) abort ();
594 context_cache.ccontext = ccontext_end1;
597 else if (context_cache.ccontext == ccontext_start1)
599 if (context_cache.context != context_none) abort ();
600 context_cache.ccontext = ccontext_none;
602 else if (context_cache.ccontext == ccontext_end1)
604 if (context_cache.context != context_block_comment) abort ();
605 context_cache.context = context_none;
606 context_cache.ccontext = ccontext_start2;
609 if (context_cache.ccontext == ccontext_start2 &&
610 context_cache.context == context_none)
612 context_cache.context = context_block_comment;
613 if (context_cache.style == comment_style_none) abort ();
615 else if (context_cache.ccontext == ccontext_none &&
616 context_cache.context == context_block_comment)
618 context_cache.context = context_none;
622 context_cache.needs_its_head_reexamined = 0;
626 context_to_symbol (enum syntactic_context context)
630 case context_none: return Qnil;
631 case context_string: return Qstring;
632 case context_comment: return Qcomment;
633 case context_block_comment: return Qblock_comment;
634 default: abort (); return Qnil; /* suppress compiler warning */
638 DEFUN ("buffer-syntactic-context", Fbuffer_syntactic_context, 0, 1, 0, /*
639 Return the syntactic context of BUFFER at point.
640 If BUFFER is nil or omitted, the current buffer is assumed.
641 The returned value is one of the following symbols:
643 nil ; meaning no special interpretation
644 string ; meaning point is within a string
645 comment ; meaning point is within a line comment
646 block-comment ; meaning point is within a block comment
648 See also the function `buffer-syntactic-context-depth', which returns
649 the current nesting-depth within all parenthesis-syntax delimiters
650 and the function `syntactically-sectionize', which will map a function
651 over each syntactic context in a region.
653 WARNING: this may alter match-data.
657 /* This function can GC */
658 struct buffer *buf = decode_buffer (buffer, 0);
659 find_context (buf, BUF_PT (buf));
660 return context_to_symbol (context_cache.context);
663 DEFUN ("buffer-syntactic-context-depth", Fbuffer_syntactic_context_depth,
665 Return the depth within all parenthesis-syntax delimiters at point.
666 If BUFFER is nil or omitted, the current buffer is assumed.
667 WARNING: this may alter match-data.
671 /* This function can GC */
672 struct buffer *buf = decode_buffer (buffer, 0);
673 find_context (buf, BUF_PT (buf));
674 return make_int (context_cache.depth);
678 DEFUN ("syntactically-sectionize", Fsyntactically_sectionize, 3, 4, 0, /*
679 Call FUNCTION for each contiguous syntactic context in the region.
680 Call the given function with four arguments: the start and end of the
681 region, a symbol representing the syntactic context, and the current
682 depth (as returned by the functions `buffer-syntactic-context' and
683 `buffer-syntactic-context-depth'). When this function is called, the
684 current buffer will be set to BUFFER.
686 WARNING: this may alter match-data.
688 (function, start, end, buffer))
690 /* This function can GC */
693 enum syntactic_context this_context;
694 Lisp_Object extent = Qnil;
696 struct buffer *buf = decode_buffer (buffer, 0);
698 get_buffer_range_char (buf, start, end, &s, &e, 0);
701 find_context (buf, pt);
707 /* skip over "blank" areas, and bug out at end-of-buffer. */
708 while (context_cache.context == context_none)
711 if (pt >= e) goto DONE_LABEL;
712 find_context (buf, pt);
714 /* We've found a non-blank area; keep going until we reach its end */
715 this_context = context_cache.context;
718 /* Minor kludge: consider the comment-start character(s) a part of
721 if (this_context == context_block_comment &&
722 context_cache.ccontext == ccontext_start2)
724 else if (this_context == context_comment)
727 edepth = context_cache.depth;
728 while (context_cache.context == this_context && pt < e)
731 find_context (buf, pt);
736 /* Minor kludge: consider the character which terminated the comment
737 a part of the comment.
739 if ((this_context == context_block_comment ||
740 this_context == context_comment)
746 /* Make sure not to pass in values that are outside the
747 actual bounds of this function. */
748 call4_in_buffer (buf, function, make_int (max (s, estart)),
749 make_int (eend == e ? e : eend - 1),
750 context_to_symbol (this_context),
759 syms_of_font_lock (void)
761 defsymbol (&Qcomment, "comment");
762 defsymbol (&Qblock_comment, "block-comment");
763 defsymbol (&Qbeginning_of_defun, "beginning-of-defun");
765 DEFSUBR (Fbuffer_syntactic_context);
766 DEFSUBR (Fbuffer_syntactic_context_depth);
767 DEFSUBR (Fsyntactically_sectionize);
771 reinit_vars_of_font_lock (void)
773 xzero (context_cache);
774 xzero (bol_context_cache);
778 vars_of_font_lock (void)
780 reinit_vars_of_font_lock ();