1 /* dfa - DFA construction routines */
2
3 /*-
4 * Copyright (c) 1990 The Regents of the University of California.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Vern Paxson.
9 *
10 * The United States Government has rights in this work pursuant
11 * to contract no. DE-AC03-76SF00098 between the United States
12 * Department of Energy and the University of California.
13 *
14 * Redistribution and use in source and binary forms with or without
15 * modification are permitted provided that: (1) source distributions retain
16 * this entire copyright notice and comment, and (2) distributions including
17 * binaries display the following acknowledgement: ``This product includes
18 * software developed by the University of California, Berkeley and its
19 * contributors'' in the documentation or other materials provided with the
20 * distribution and in all advertising materials mentioning features or use
21 * of this software. Neither the name of the University nor the names of
22 * its contributors may be used to endorse or promote products derived from
23 * this software without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
25 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
26 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
27 */
28
29 /* $Header: /home/daffy/u0/vern/flex/RCS/dfa.c,v 2.26 95/04/20 13:53:14 vern Exp $ */
30
31 #include "flexdef.h"
32
33
34 /* declare functions that have forward references */
35
36 void dump_associated_rules PROTO((FILE*, int));
37 void dump_transitions PROTO((FILE*, int[]));
38 void sympartition PROTO((int[], int, int[], int[]));
39 int symfollowset PROTO((int[], int, int, int[]));
40
41
42 /* check_for_backing_up - check a DFA state for backing up
43 *
44 * synopsis
45 * void check_for_backing_up( int ds, int state[numecs] );
46 *
47 * ds is the number of the state to check and state[] is its out-transitions,
48 * indexed by equivalence class.
49 */
50
check_for_backing_up(ds,state)51 void check_for_backing_up( ds, state )
52 int ds;
53 int state[];
54 {
55 if ( (reject && ! dfaacc[ds].dfaacc_set) ||
56 (! reject && ! dfaacc[ds].dfaacc_state) )
57 { /* state is non-accepting */
58 ++num_backing_up;
59
60 if ( backing_up_report )
61 {
62 fprintf( backing_up_file,
63 _( "State #%d is non-accepting -\n" ), ds );
64
65 /* identify the state */
66 dump_associated_rules( backing_up_file, ds );
67
68 /* Now identify it further using the out- and
69 * jam-transitions.
70 */
71 dump_transitions( backing_up_file, state );
72
73 putc( '\n', backing_up_file );
74 }
75 }
76 }
77
78
79 /* check_trailing_context - check to see if NFA state set constitutes
80 * "dangerous" trailing context
81 *
82 * synopsis
83 * void check_trailing_context( int nfa_states[num_states+1], int num_states,
84 * int accset[nacc+1], int nacc );
85 *
86 * NOTES
87 * Trailing context is "dangerous" if both the head and the trailing
88 * part are of variable size \and/ there's a DFA state which contains
89 * both an accepting state for the head part of the rule and NFA states
90 * which occur after the beginning of the trailing context.
91 *
92 * When such a rule is matched, it's impossible to tell if having been
93 * in the DFA state indicates the beginning of the trailing context or
94 * further-along scanning of the pattern. In these cases, a warning
95 * message is issued.
96 *
97 * nfa_states[1 .. num_states] is the list of NFA states in the DFA.
98 * accset[1 .. nacc] is the list of accepting numbers for the DFA state.
99 */
100
check_trailing_context(nfa_states,num_states,accset,nacc)101 void check_trailing_context( nfa_states, num_states, accset, nacc )
102 int *nfa_states, num_states;
103 int *accset;
104 int nacc;
105 {
106 register int i, j;
107
108 for ( i = 1; i <= num_states; ++i )
109 {
110 int ns = nfa_states[i];
111 register int type = state_type[ns];
112 register int ar = assoc_rule[ns];
113
114 if ( type == STATE_NORMAL || rule_type[ar] != RULE_VARIABLE )
115 { /* do nothing */
116 }
117
118 else if ( type == STATE_TRAILING_CONTEXT )
119 {
120 /* Potential trouble. Scan set of accepting numbers
121 * for the one marking the end of the "head". We
122 * assume that this looping will be fairly cheap
123 * since it's rare that an accepting number set
124 * is large.
125 */
126 for ( j = 1; j <= nacc; ++j )
127 if ( accset[j] & YY_TRAILING_HEAD_MASK )
128 {
129 line_warning(
130 _( "dangerous trailing context" ),
131 rule_linenum[ar] );
132 return;
133 }
134 }
135 }
136 }
137
138
139 /* dump_associated_rules - list the rules associated with a DFA state
140 *
141 * Goes through the set of NFA states associated with the DFA and
142 * extracts the first MAX_ASSOC_RULES unique rules, sorts them,
143 * and writes a report to the given file.
144 */
145
dump_associated_rules(file,ds)146 void dump_associated_rules( file, ds )
147 FILE *file;
148 int ds;
149 {
150 register int i, j;
151 register int num_associated_rules = 0;
152 int rule_set[MAX_ASSOC_RULES + 1];
153 int *dset = dss[ds];
154 int size = dfasiz[ds];
155
156 for ( i = 1; i <= size; ++i )
157 {
158 register int rule_num = rule_linenum[assoc_rule[dset[i]]];
159
160 for ( j = 1; j <= num_associated_rules; ++j )
161 if ( rule_num == rule_set[j] )
162 break;
163
164 if ( j > num_associated_rules )
165 { /* new rule */
166 if ( num_associated_rules < MAX_ASSOC_RULES )
167 rule_set[++num_associated_rules] = rule_num;
168 }
169 }
170
171 bubble( rule_set, num_associated_rules );
172
173 fprintf( file, _( " associated rule line numbers:" ) );
174
175 for ( i = 1; i <= num_associated_rules; ++i )
176 {
177 if ( i % 8 == 1 )
178 putc( '\n', file );
179
180 fprintf( file, "\t%d", rule_set[i] );
181 }
182
183 putc( '\n', file );
184 }
185
186
187 /* dump_transitions - list the transitions associated with a DFA state
188 *
189 * synopsis
190 * dump_transitions( FILE *file, int state[numecs] );
191 *
192 * Goes through the set of out-transitions and lists them in human-readable
193 * form (i.e., not as equivalence classes); also lists jam transitions
194 * (i.e., all those which are not out-transitions, plus EOF). The dump
195 * is done to the given file.
196 */
197
dump_transitions(file,state)198 void dump_transitions( file, state )
199 FILE *file;
200 int state[];
201 {
202 register int i, ec;
203 int out_char_set[CSIZE];
204
205 for ( i = 0; i < csize; ++i )
206 {
207 ec = ABS( ecgroup[i] );
208 out_char_set[i] = state[ec];
209 }
210
211 fprintf( file, _( " out-transitions: " ) );
212
213 list_character_set( file, out_char_set );
214
215 /* now invert the members of the set to get the jam transitions */
216 for ( i = 0; i < csize; ++i )
217 out_char_set[i] = ! out_char_set[i];
218
219 fprintf( file, _( "\n jam-transitions: EOF " ) );
220
221 list_character_set( file, out_char_set );
222
223 putc( '\n', file );
224 }
225
226
227 /* epsclosure - construct the epsilon closure of a set of ndfa states
228 *
229 * synopsis
230 * int *epsclosure( int t[num_states], int *numstates_addr,
231 * int accset[num_rules+1], int *nacc_addr,
232 * int *hashval_addr );
233 *
234 * NOTES
235 * The epsilon closure is the set of all states reachable by an arbitrary
236 * number of epsilon transitions, which themselves do not have epsilon
237 * transitions going out, unioned with the set of states which have non-null
238 * accepting numbers. t is an array of size numstates of nfa state numbers.
239 * Upon return, t holds the epsilon closure and *numstates_addr is updated.
240 * accset holds a list of the accepting numbers, and the size of accset is
241 * given by *nacc_addr. t may be subjected to reallocation if it is not
242 * large enough to hold the epsilon closure.
243 *
244 * hashval is the hash value for the dfa corresponding to the state set.
245 */
246
epsclosure(t,ns_addr,accset,nacc_addr,hv_addr)247 int *epsclosure( t, ns_addr, accset, nacc_addr, hv_addr )
248 int *t, *ns_addr, accset[], *nacc_addr, *hv_addr;
249 {
250 register int stkpos, ns, tsp;
251 int numstates = *ns_addr, nacc, hashval, transsym, nfaccnum;
252 int stkend, nstate;
253 static int did_stk_init = false, *stk;
254
255 #define MARK_STATE(state) \
256 trans1[state] = trans1[state] - MARKER_DIFFERENCE;
257
258 #define IS_MARKED(state) (trans1[state] < 0)
259
260 #define UNMARK_STATE(state) \
261 trans1[state] = trans1[state] + MARKER_DIFFERENCE;
262
263 #define CHECK_ACCEPT(state) \
264 { \
265 nfaccnum = accptnum[state]; \
266 if ( nfaccnum != NIL ) \
267 accset[++nacc] = nfaccnum; \
268 }
269
270 #define DO_REALLOCATION \
271 { \
272 current_max_dfa_size += MAX_DFA_SIZE_INCREMENT; \
273 ++num_reallocs; \
274 t = reallocate_integer_array( t, current_max_dfa_size ); \
275 stk = reallocate_integer_array( stk, current_max_dfa_size ); \
276 } \
277
278 #define PUT_ON_STACK(state) \
279 { \
280 if ( ++stkend >= current_max_dfa_size ) \
281 DO_REALLOCATION \
282 stk[stkend] = state; \
283 MARK_STATE(state) \
284 }
285
286 #define ADD_STATE(state) \
287 { \
288 if ( ++numstates >= current_max_dfa_size ) \
289 DO_REALLOCATION \
290 t[numstates] = state; \
291 hashval += state; \
292 }
293
294 #define STACK_STATE(state) \
295 { \
296 PUT_ON_STACK(state) \
297 CHECK_ACCEPT(state) \
298 if ( nfaccnum != NIL || transchar[state] != SYM_EPSILON ) \
299 ADD_STATE(state) \
300 }
301
302
303 if ( ! did_stk_init )
304 {
305 stk = allocate_integer_array( current_max_dfa_size );
306 did_stk_init = true;
307 }
308
309 nacc = stkend = hashval = 0;
310
311 for ( nstate = 1; nstate <= numstates; ++nstate )
312 {
313 ns = t[nstate];
314
315 /* The state could be marked if we've already pushed it onto
316 * the stack.
317 */
318 if ( ! IS_MARKED(ns) )
319 {
320 PUT_ON_STACK(ns)
321 CHECK_ACCEPT(ns)
322 hashval += ns;
323 }
324 }
325
326 for ( stkpos = 1; stkpos <= stkend; ++stkpos )
327 {
328 ns = stk[stkpos];
329 transsym = transchar[ns];
330
331 if ( transsym == SYM_EPSILON )
332 {
333 tsp = trans1[ns] + MARKER_DIFFERENCE;
334
335 if ( tsp != NO_TRANSITION )
336 {
337 if ( ! IS_MARKED(tsp) )
338 STACK_STATE(tsp)
339
340 tsp = trans2[ns];
341
342 if ( tsp != NO_TRANSITION && ! IS_MARKED(tsp) )
343 STACK_STATE(tsp)
344 }
345 }
346 }
347
348 /* Clear out "visit" markers. */
349
350 for ( stkpos = 1; stkpos <= stkend; ++stkpos )
351 {
352 if ( IS_MARKED(stk[stkpos]) )
353 UNMARK_STATE(stk[stkpos])
354 else
355 flexfatal(
356 _( "consistency check failed in epsclosure()" ) );
357 }
358
359 *ns_addr = numstates;
360 *hv_addr = hashval;
361 *nacc_addr = nacc;
362
363 return t;
364 }
365
366
367 /* increase_max_dfas - increase the maximum number of DFAs */
368
increase_max_dfas()369 void increase_max_dfas()
370 {
371 current_max_dfas += MAX_DFAS_INCREMENT;
372
373 ++num_reallocs;
374
375 base = reallocate_integer_array( base, current_max_dfas );
376 def = reallocate_integer_array( def, current_max_dfas );
377 dfasiz = reallocate_integer_array( dfasiz, current_max_dfas );
378 accsiz = reallocate_integer_array( accsiz, current_max_dfas );
379 dhash = reallocate_integer_array( dhash, current_max_dfas );
380 dss = reallocate_int_ptr_array( dss, current_max_dfas );
381 dfaacc = reallocate_dfaacc_union( dfaacc, current_max_dfas );
382
383 if ( nultrans )
384 nultrans =
385 reallocate_integer_array( nultrans, current_max_dfas );
386 }
387
388
389 /* ntod - convert an ndfa to a dfa
390 *
391 * Creates the dfa corresponding to the ndfa we've constructed. The
392 * dfa starts out in state #1.
393 */
394
ntod()395 void ntod()
396 {
397 int *accset, ds, nacc, newds;
398 int sym, hashval, numstates, dsize;
399 int num_full_table_rows; /* used only for -f */
400 int *nset, *dset;
401 int targptr, totaltrans, i, comstate, comfreq, targ;
402 int symlist[CSIZE + 1];
403 int num_start_states;
404 int todo_head, todo_next;
405
406 /* Note that the following are indexed by *equivalence classes*
407 * and not by characters. Since equivalence classes are indexed
408 * beginning with 1, even if the scanner accepts NUL's, this
409 * means that (since every character is potentially in its own
410 * equivalence class) these arrays must have room for indices
411 * from 1 to CSIZE, so their size must be CSIZE + 1.
412 */
413 int duplist[CSIZE + 1], state[CSIZE + 1];
414 int targfreq[CSIZE + 1], targstate[CSIZE + 1];
415
416 accset = allocate_integer_array( num_rules + 1 );
417 nset = allocate_integer_array( current_max_dfa_size );
418
419 /* The "todo" queue is represented by the head, which is the DFA
420 * state currently being processed, and the "next", which is the
421 * next DFA state number available (not in use). We depend on the
422 * fact that snstods() returns DFA's \in increasing order/, and thus
423 * need only know the bounds of the dfas to be processed.
424 */
425 todo_head = todo_next = 0;
426
427 for ( i = 0; i <= csize; ++i )
428 {
429 duplist[i] = NIL;
430 symlist[i] = false;
431 }
432
433 for ( i = 0; i <= num_rules; ++i )
434 accset[i] = NIL;
435
436 if ( trace )
437 {
438 dumpnfa( scset[1] );
439 fputs( _( "\n\nDFA Dump:\n\n" ), stderr );
440 }
441
442 inittbl();
443
444 /* Check to see whether we should build a separate table for
445 * transitions on NUL characters. We don't do this for full-speed
446 * (-F) scanners, since for them we don't have a simple state
447 * number lying around with which to index the table. We also
448 * don't bother doing it for scanners unless (1) NUL is in its own
449 * equivalence class (indicated by a positive value of
450 * ecgroup[NUL]), (2) NUL's equivalence class is the last
451 * equivalence class, and (3) the number of equivalence classes is
452 * the same as the number of characters. This latter case comes
453 * about when useecs is false or when it's true but every character
454 * still manages to land in its own class (unlikely, but it's
455 * cheap to check for). If all these things are true then the
456 * character code needed to represent NUL's equivalence class for
457 * indexing the tables is going to take one more bit than the
458 * number of characters, and therefore we won't be assured of
459 * being able to fit it into a YY_CHAR variable. This rules out
460 * storing the transitions in a compressed table, since the code
461 * for interpreting them uses a YY_CHAR variable (perhaps it
462 * should just use an integer, though; this is worth pondering ...
463 * ###).
464 *
465 * Finally, for full tables, we want the number of entries in the
466 * table to be a power of two so the array references go fast (it
467 * will just take a shift to compute the major index). If
468 * encoding NUL's transitions in the table will spoil this, we
469 * give it its own table (note that this will be the case if we're
470 * not using equivalence classes).
471 */
472
473 /* Note that the test for ecgroup[0] == numecs below accomplishes
474 * both (1) and (2) above
475 */
476 if ( ! fullspd && ecgroup[0] == numecs )
477 {
478 /* NUL is alone in its equivalence class, which is the
479 * last one.
480 */
481 int use_NUL_table = (numecs == csize);
482
483 if ( fulltbl && ! use_NUL_table )
484 {
485 /* We still may want to use the table if numecs
486 * is a power of 2.
487 */
488 int power_of_two;
489
490 for ( power_of_two = 1; power_of_two <= csize;
491 power_of_two *= 2 )
492 if ( numecs == power_of_two )
493 {
494 use_NUL_table = true;
495 break;
496 }
497 }
498
499 if ( use_NUL_table )
500 nultrans = allocate_integer_array( current_max_dfas );
501
502 /* From now on, nultrans != nil indicates that we're
503 * saving null transitions for later, separate encoding.
504 */
505 }
506
507
508 if ( fullspd )
509 {
510 for ( i = 0; i <= numecs; ++i )
511 state[i] = 0;
512
513 place_state( state, 0, 0 );
514 dfaacc[0].dfaacc_state = 0;
515 }
516
517 else if ( fulltbl )
518 {
519 if ( nultrans )
520 /* We won't be including NUL's transitions in the
521 * table, so build it for entries from 0 .. numecs - 1.
522 */
523 num_full_table_rows = numecs;
524
525 else
526 /* Take into account the fact that we'll be including
527 * the NUL entries in the transition table. Build it
528 * from 0 .. numecs.
529 */
530 num_full_table_rows = numecs + 1;
531
532 /* Unless -Ca, declare it "short" because it's a real
533 * long-shot that that won't be large enough.
534 */
535 out_str_dec( "static yyconst %s yy_nxt[][%d] =\n {\n",
536 /* '}' so vi doesn't get too confused */
537 long_align ? "long" : "short", num_full_table_rows );
538
539 outn( " {" );
540
541 /* Generate 0 entries for state #0. */
542 for ( i = 0; i < num_full_table_rows; ++i )
543 mk2data( 0 );
544
545 dataflush();
546 outn( " },\n" );
547 }
548
549 /* Create the first states. */
550
551 num_start_states = lastsc * 2;
552
553 for ( i = 1; i <= num_start_states; ++i )
554 {
555 numstates = 1;
556
557 /* For each start condition, make one state for the case when
558 * we're at the beginning of the line (the '^' operator) and
559 * one for the case when we're not.
560 */
561 if ( i % 2 == 1 )
562 nset[numstates] = scset[(i / 2) + 1];
563 else
564 nset[numstates] =
565 mkbranch( scbol[i / 2], scset[i / 2] );
566
567 nset = epsclosure( nset, &numstates, accset, &nacc, &hashval );
568
569 if ( snstods( nset, numstates, accset, nacc, hashval, &ds ) )
570 {
571 numas += nacc;
572 totnst += numstates;
573 ++todo_next;
574
575 if ( variable_trailing_context_rules && nacc > 0 )
576 check_trailing_context( nset, numstates,
577 accset, nacc );
578 }
579 }
580
581 if ( ! fullspd )
582 {
583 if ( ! snstods( nset, 0, accset, 0, 0, &end_of_buffer_state ) )
584 flexfatal(
585 _( "could not create unique end-of-buffer state" ) );
586
587 ++numas;
588 ++num_start_states;
589 ++todo_next;
590 }
591
592 while ( todo_head < todo_next )
593 {
594 targptr = 0;
595 totaltrans = 0;
596
597 for ( i = 1; i <= numecs; ++i )
598 state[i] = 0;
599
600 ds = ++todo_head;
601
602 dset = dss[ds];
603 dsize = dfasiz[ds];
604
605 if ( trace )
606 fprintf( stderr, _( "state # %d:\n" ), ds );
607
608 sympartition( dset, dsize, symlist, duplist );
609
610 for ( sym = 1; sym <= numecs; ++sym )
611 {
612 if ( symlist[sym] )
613 {
614 symlist[sym] = 0;
615
616 if ( duplist[sym] == NIL )
617 {
618 /* Symbol has unique out-transitions. */
619 numstates = symfollowset( dset, dsize,
620 sym, nset );
621 nset = epsclosure( nset, &numstates,
622 accset, &nacc, &hashval );
623
624 if ( snstods( nset, numstates, accset,
625 nacc, hashval, &newds ) )
626 {
627 totnst = totnst + numstates;
628 ++todo_next;
629 numas += nacc;
630
631 if (
632 variable_trailing_context_rules &&
633 nacc > 0 )
634 check_trailing_context(
635 nset, numstates,
636 accset, nacc );
637 }
638
639 state[sym] = newds;
640
641 if ( trace )
642 fprintf( stderr, "\t%d\t%d\n",
643 sym, newds );
644
645 targfreq[++targptr] = 1;
646 targstate[targptr] = newds;
647 ++numuniq;
648 }
649
650 else
651 {
652 /* sym's equivalence class has the same
653 * transitions as duplist(sym)'s
654 * equivalence class.
655 */
656 targ = state[duplist[sym]];
657 state[sym] = targ;
658
659 if ( trace )
660 fprintf( stderr, "\t%d\t%d\n",
661 sym, targ );
662
663 /* Update frequency count for
664 * destination state.
665 */
666
667 i = 0;
668 while ( targstate[++i] != targ )
669 ;
670
671 ++targfreq[i];
672 ++numdup;
673 }
674
675 ++totaltrans;
676 duplist[sym] = NIL;
677 }
678 }
679
680 if ( caseins && ! useecs )
681 {
682 register int j;
683
684 for ( i = 'A', j = 'a'; i <= 'Z'; ++i, ++j )
685 {
686 if ( state[i] == 0 && state[j] != 0 )
687 /* We're adding a transition. */
688 ++totaltrans;
689
690 else if ( state[i] != 0 && state[j] == 0 )
691 /* We're taking away a transition. */
692 --totaltrans;
693
694 state[i] = state[j];
695 }
696 }
697
698 numsnpairs += totaltrans;
699
700 if ( ds > num_start_states )
701 check_for_backing_up( ds, state );
702
703 if ( nultrans )
704 {
705 nultrans[ds] = state[NUL_ec];
706 state[NUL_ec] = 0; /* remove transition */
707 }
708
709 if ( fulltbl )
710 {
711 outn( " {" );
712
713 /* Supply array's 0-element. */
714 if ( ds == end_of_buffer_state )
715 mk2data( -end_of_buffer_state );
716 else
717 mk2data( end_of_buffer_state );
718
719 for ( i = 1; i < num_full_table_rows; ++i )
720 /* Jams are marked by negative of state
721 * number.
722 */
723 mk2data( state[i] ? state[i] : -ds );
724
725 dataflush();
726 outn( " },\n" );
727 }
728
729 else if ( fullspd )
730 place_state( state, ds, totaltrans );
731
732 else if ( ds == end_of_buffer_state )
733 /* Special case this state to make sure it does what
734 * it's supposed to, i.e., jam on end-of-buffer.
735 */
736 stack1( ds, 0, 0, JAMSTATE );
737
738 else /* normal, compressed state */
739 {
740 /* Determine which destination state is the most
741 * common, and how many transitions to it there are.
742 */
743
744 comfreq = 0;
745 comstate = 0;
746
747 for ( i = 1; i <= targptr; ++i )
748 if ( targfreq[i] > comfreq )
749 {
750 comfreq = targfreq[i];
751 comstate = targstate[i];
752 }
753
754 bldtbl( state, ds, totaltrans, comstate, comfreq );
755 }
756 }
757
758 if ( fulltbl )
759 dataend();
760
761 else if ( ! fullspd )
762 {
763 cmptmps(); /* create compressed template entries */
764
765 /* Create tables for all the states with only one
766 * out-transition.
767 */
768 while ( onesp > 0 )
769 {
770 mk1tbl( onestate[onesp], onesym[onesp], onenext[onesp],
771 onedef[onesp] );
772 --onesp;
773 }
774
775 mkdeftbl();
776 }
777
778 flex_free( (void *) accset );
779 flex_free( (void *) nset );
780 }
781
782
783 /* snstods - converts a set of ndfa states into a dfa state
784 *
785 * synopsis
786 * is_new_state = snstods( int sns[numstates], int numstates,
787 * int accset[num_rules+1], int nacc,
788 * int hashval, int *newds_addr );
789 *
790 * On return, the dfa state number is in newds.
791 */
792
snstods(sns,numstates,accset,nacc,hashval,newds_addr)793 int snstods( sns, numstates, accset, nacc, hashval, newds_addr )
794 int sns[], numstates, accset[], nacc, hashval, *newds_addr;
795 {
796 int didsort = 0;
797 register int i, j;
798 int newds, *oldsns;
799
800 for ( i = 1; i <= lastdfa; ++i )
801 if ( hashval == dhash[i] )
802 {
803 if ( numstates == dfasiz[i] )
804 {
805 oldsns = dss[i];
806
807 if ( ! didsort )
808 {
809 /* We sort the states in sns so we
810 * can compare it to oldsns quickly.
811 * We use bubble because there probably
812 * aren't very many states.
813 */
814 bubble( sns, numstates );
815 didsort = 1;
816 }
817
818 for ( j = 1; j <= numstates; ++j )
819 if ( sns[j] != oldsns[j] )
820 break;
821
822 if ( j > numstates )
823 {
824 ++dfaeql;
825 *newds_addr = i;
826 return 0;
827 }
828
829 ++hshcol;
830 }
831
832 else
833 ++hshsave;
834 }
835
836 /* Make a new dfa. */
837
838 if ( ++lastdfa >= current_max_dfas )
839 increase_max_dfas();
840
841 newds = lastdfa;
842
843 dss[newds] = allocate_integer_array( numstates + 1 );
844
845 /* If we haven't already sorted the states in sns, we do so now,
846 * so that future comparisons with it can be made quickly.
847 */
848
849 if ( ! didsort )
850 bubble( sns, numstates );
851
852 for ( i = 1; i <= numstates; ++i )
853 dss[newds][i] = sns[i];
854
855 dfasiz[newds] = numstates;
856 dhash[newds] = hashval;
857
858 if ( nacc == 0 )
859 {
860 if ( reject )
861 dfaacc[newds].dfaacc_set = (int *) 0;
862 else
863 dfaacc[newds].dfaacc_state = 0;
864
865 accsiz[newds] = 0;
866 }
867
868 else if ( reject )
869 {
870 /* We sort the accepting set in increasing order so the
871 * disambiguating rule that the first rule listed is considered
872 * match in the event of ties will work. We use a bubble
873 * sort since the list is probably quite small.
874 */
875
876 bubble( accset, nacc );
877
878 dfaacc[newds].dfaacc_set = allocate_integer_array( nacc + 1 );
879
880 /* Save the accepting set for later */
881 for ( i = 1; i <= nacc; ++i )
882 {
883 dfaacc[newds].dfaacc_set[i] = accset[i];
884
885 if ( accset[i] <= num_rules )
886 /* Who knows, perhaps a REJECT can yield
887 * this rule.
888 */
889 rule_useful[accset[i]] = true;
890 }
891
892 accsiz[newds] = nacc;
893 }
894
895 else
896 {
897 /* Find lowest numbered rule so the disambiguating rule
898 * will work.
899 */
900 j = num_rules + 1;
901
902 for ( i = 1; i <= nacc; ++i )
903 if ( accset[i] < j )
904 j = accset[i];
905
906 dfaacc[newds].dfaacc_state = j;
907
908 if ( j <= num_rules )
909 rule_useful[j] = true;
910 }
911
912 *newds_addr = newds;
913
914 return 1;
915 }
916
917
918 /* symfollowset - follow the symbol transitions one step
919 *
920 * synopsis
921 * numstates = symfollowset( int ds[current_max_dfa_size], int dsize,
922 * int transsym, int nset[current_max_dfa_size] );
923 */
924
symfollowset(ds,dsize,transsym,nset)925 int symfollowset( ds, dsize, transsym, nset )
926 int ds[], dsize, transsym, nset[];
927 {
928 int ns, tsp, sym, i, j, lenccl, ch, numstates, ccllist;
929
930 numstates = 0;
931
932 for ( i = 1; i <= dsize; ++i )
933 { /* for each nfa state ns in the state set of ds */
934 ns = ds[i];
935 sym = transchar[ns];
936 tsp = trans1[ns];
937
938 if ( sym < 0 )
939 { /* it's a character class */
940 sym = -sym;
941 ccllist = cclmap[sym];
942 lenccl = ccllen[sym];
943
944 if ( cclng[sym] )
945 {
946 for ( j = 0; j < lenccl; ++j )
947 {
948 /* Loop through negated character
949 * class.
950 */
951 ch = ccltbl[ccllist + j];
952
953 if ( ch == 0 )
954 ch = NUL_ec;
955
956 if ( ch > transsym )
957 /* Transsym isn't in negated
958 * ccl.
959 */
960 break;
961
962 else if ( ch == transsym )
963 /* next 2 */ goto bottom;
964 }
965
966 /* Didn't find transsym in ccl. */
967 nset[++numstates] = tsp;
968 }
969
970 else
971 for ( j = 0; j < lenccl; ++j )
972 {
973 ch = ccltbl[ccllist + j];
974
975 if ( ch == 0 )
976 ch = NUL_ec;
977
978 if ( ch > transsym )
979 break;
980 else if ( ch == transsym )
981 {
982 nset[++numstates] = tsp;
983 break;
984 }
985 }
986 }
987
988 else if ( sym >= 'A' && sym <= 'Z' && caseins )
989 flexfatal(
990 _( "consistency check failed in symfollowset" ) );
991
992 else if ( sym == SYM_EPSILON )
993 { /* do nothing */
994 }
995
996 else if ( ABS( ecgroup[sym] ) == transsym )
997 nset[++numstates] = tsp;
998
999 bottom: ;
1000 }
1001
1002 return numstates;
1003 }
1004
1005
1006 /* sympartition - partition characters with same out-transitions
1007 *
1008 * synopsis
1009 * sympartition( int ds[current_max_dfa_size], int numstates,
1010 * int symlist[numecs], int duplist[numecs] );
1011 */
1012
sympartition(ds,numstates,symlist,duplist)1013 void sympartition( ds, numstates, symlist, duplist )
1014 int ds[], numstates;
1015 int symlist[], duplist[];
1016 {
1017 int tch, i, j, k, ns, dupfwd[CSIZE + 1], lenccl, cclp, ich;
1018
1019 /* Partitioning is done by creating equivalence classes for those
1020 * characters which have out-transitions from the given state. Thus
1021 * we are really creating equivalence classes of equivalence classes.
1022 */
1023
1024 for ( i = 1; i <= numecs; ++i )
1025 { /* initialize equivalence class list */
1026 duplist[i] = i - 1;
1027 dupfwd[i] = i + 1;
1028 }
1029
1030 duplist[1] = NIL;
1031 dupfwd[numecs] = NIL;
1032
1033 for ( i = 1; i <= numstates; ++i )
1034 {
1035 ns = ds[i];
1036 tch = transchar[ns];
1037
1038 if ( tch != SYM_EPSILON )
1039 {
1040 if ( tch < -lastccl || tch >= csize )
1041 {
1042 flexfatal(
1043 _( "bad transition character detected in sympartition()" ) );
1044 }
1045
1046 if ( tch >= 0 )
1047 { /* character transition */
1048 int ec = ecgroup[tch];
1049
1050 mkechar( ec, dupfwd, duplist );
1051 symlist[ec] = 1;
1052 }
1053
1054 else
1055 { /* character class */
1056 tch = -tch;
1057
1058 lenccl = ccllen[tch];
1059 cclp = cclmap[tch];
1060 mkeccl( ccltbl + cclp, lenccl, dupfwd,
1061 duplist, numecs, NUL_ec );
1062
1063 if ( cclng[tch] )
1064 {
1065 j = 0;
1066
1067 for ( k = 0; k < lenccl; ++k )
1068 {
1069 ich = ccltbl[cclp + k];
1070
1071 if ( ich == 0 )
1072 ich = NUL_ec;
1073
1074 for ( ++j; j < ich; ++j )
1075 symlist[j] = 1;
1076 }
1077
1078 for ( ++j; j <= numecs; ++j )
1079 symlist[j] = 1;
1080 }
1081
1082 else
1083 for ( k = 0; k < lenccl; ++k )
1084 {
1085 ich = ccltbl[cclp + k];
1086
1087 if ( ich == 0 )
1088 ich = NUL_ec;
1089
1090 symlist[ich] = 1;
1091 }
1092 }
1093 }
1094 }
1095 }
1096