summaryrefslogtreecommitdiffstats
path: root/usr.bin/lex/nfa.c
blob: d101f370e78bbb7bed2b811eb0090ab0bc594b99 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
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
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
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
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
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
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
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
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
/* nfa - NFA construction routines */

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Vern Paxson.
 * 
 * The United States Government has rights in this work pursuant
 * to contract no. DE-AC03-76SF00098 between the United States
 * Department of Energy and the University of California.
 *
 * Redistribution and use in source and binary forms are permitted provided
 * that: (1) source distributions retain this entire copyright notice and
 * comment, and (2) distributions including binaries display the following
 * acknowledgement:  ``This product includes software developed by the
 * University of California, Berkeley and its contributors'' in the
 * documentation or other materials provided with the distribution and in
 * all advertising materials mentioning features or use of this software.
 * Neither the name of the University nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/* $Header: /home/daffy/u0/vern/flex/RCS/nfa.c,v 2.17 95/03/04 16:11:42 vern Exp $ */
/* $FreeBSD$ */

#include "flexdef.h"


/* declare functions that have forward references */

int dupmachine PROTO((int));
void mkxtion PROTO((int, int));


/* add_accept - add an accepting state to a machine
 *
 * accepting_number becomes mach's accepting number.
 */

void add_accept( mach, accepting_number )
int mach, accepting_number;
	{
	/* Hang the accepting number off an epsilon state.  if it is associated
	 * with a state that has a non-epsilon out-transition, then the state
	 * will accept BEFORE it makes that transition, i.e., one character
	 * too soon.
	 */

	if ( transchar[finalst[mach]] == SYM_EPSILON )
		accptnum[finalst[mach]] = accepting_number;

	else
		{
		int astate = mkstate( SYM_EPSILON );
		accptnum[astate] = accepting_number;
		(void) link_machines( mach, astate );
		}
	}


/* copysingl - make a given number of copies of a singleton machine
 *
 * synopsis
 *
 *   newsng = copysingl( singl, num );
 *
 *     newsng - a new singleton composed of num copies of singl
 *     singl  - a singleton machine
 *     num    - the number of copies of singl to be present in newsng
 */

int copysingl( singl, num )
int singl, num;
	{
	int copy, i;

	copy = mkstate( SYM_EPSILON );

	for ( i = 1; i <= num; ++i )
		copy = link_machines( copy, dupmachine( singl ) );

	return copy;
	}


/* dumpnfa - debugging routine to write out an nfa */

void dumpnfa( state1 )
int state1;

	{
	int sym, tsp1, tsp2, anum, ns;

	fprintf( stderr,
	_( "\n\n********** beginning dump of nfa with start state %d\n" ),
		state1 );

	/* We probably should loop starting at firstst[state1] and going to
	 * lastst[state1], but they're not maintained properly when we "or"
	 * all of the rules together.  So we use our knowledge that the machine
	 * starts at state 1 and ends at lastnfa.
	 */

	/* for ( ns = firstst[state1]; ns <= lastst[state1]; ++ns ) */
	for ( ns = 1; ns <= lastnfa; ++ns )
		{
		fprintf( stderr, _( "state # %4d\t" ), ns );

		sym = transchar[ns];
		tsp1 = trans1[ns];
		tsp2 = trans2[ns];
		anum = accptnum[ns];

		fprintf( stderr, "%3d:  %4d, %4d", sym, tsp1, tsp2 );

		if ( anum != NIL )
			fprintf( stderr, "  [%d]", anum );

		fprintf( stderr, "\n" );
		}

	fprintf( stderr, _( "********** end of dump\n" ) );
	}


/* dupmachine - make a duplicate of a given machine
 *
 * synopsis
 *
 *   copy = dupmachine( mach );
 *
 *     copy - holds duplicate of mach
 *     mach - machine to be duplicated
 *
 * note that the copy of mach is NOT an exact duplicate; rather, all the
 * transition states values are adjusted so that the copy is self-contained,
 * as the original should have been.
 *
 * also note that the original MUST be contiguous, with its low and high
 * states accessible by the arrays firstst and lastst
 */

int dupmachine( mach )
int mach;
	{
	int i, init, state_offset;
	int state = 0;
	int last = lastst[mach];

	for ( i = firstst[mach]; i <= last; ++i )
		{
		state = mkstate( transchar[i] );

		if ( trans1[i] != NO_TRANSITION )
			{
			mkxtion( finalst[state], trans1[i] + state - i );

			if ( transchar[i] == SYM_EPSILON &&
			     trans2[i] != NO_TRANSITION )
				mkxtion( finalst[state],
					trans2[i] + state - i );
			}

		accptnum[state] = accptnum[i];
		}

	if ( state == 0 )
		flexfatal( _( "empty machine in dupmachine()" ) );

	state_offset = state - i + 1;

	init = mach + state_offset;
	firstst[init] = firstst[mach] + state_offset;
	finalst[init] = finalst[mach] + state_offset;
	lastst[init] = lastst[mach] + state_offset;

	return init;
	}


/* finish_rule - finish up the processing for a rule
 *
 * An accepting number is added to the given machine.  If variable_trail_rule
 * is true then the rule has trailing context and both the head and trail
 * are variable size.  Otherwise if headcnt or trailcnt is non-zero then
 * the machine recognizes a pattern with trailing context and headcnt is
 * the number of characters in the matched part of the pattern, or zero
 * if the matched part has variable length.  trailcnt is the number of
 * trailing context characters in the pattern, or zero if the trailing
 * context has variable length.
 */

void finish_rule( mach, variable_trail_rule, headcnt, trailcnt )
int mach, variable_trail_rule, headcnt, trailcnt;
	{
	char action_text[MAXLINE];

	add_accept( mach, num_rules );

	/* We did this in new_rule(), but it often gets the wrong
	 * number because we do it before we start parsing the current rule.
	 */
	rule_linenum[num_rules] = linenum;

	/* If this is a continued action, then the line-number has already
	 * been updated, giving us the wrong number.
	 */
	if ( continued_action )
		--rule_linenum[num_rules];

	sprintf( action_text, "case %d:\n", num_rules );
	add_action( action_text );

	if ( variable_trail_rule )
		{
		rule_type[num_rules] = RULE_VARIABLE;

		if ( performance_report > 0 )
			fprintf( stderr,
			_( "Variable trailing context rule at line %d\n" ),
				rule_linenum[num_rules] );

		variable_trailing_context_rules = true;
		}

	else
		{
		rule_type[num_rules] = RULE_NORMAL;

		if ( headcnt > 0 || trailcnt > 0 )
			{
			/* Do trailing context magic to not match the trailing
			 * characters.
			 */
			char *scanner_cp = "yy_c_buf_p = yy_cp";
			char *scanner_bp = "yy_bp";

			add_action(
	"*yy_cp = yy_hold_char; /* undo effects of setting up yytext */\n" );

			if ( headcnt > 0 )
				{
				sprintf( action_text, "%s = %s + %d;\n",
				scanner_cp, scanner_bp, headcnt );
				add_action( action_text );
				}

			else
				{
				sprintf( action_text, "%s -= %d;\n",
					scanner_cp, trailcnt );
				add_action( action_text );
				}

			add_action(
			"YY_DO_BEFORE_ACTION; /* set up yytext again */\n" );
			}
		}

	/* Okay, in the action code at this point yytext and yyleng have
	 * their proper final values for this rule, so here's the point
	 * to do any user action.  But don't do it for continued actions,
	 * as that'll result in multiple YY_RULE_SETUP's.
	 */
	if ( ! continued_action )
		add_action( "YY_RULE_SETUP\n" );

	line_directive_out( (FILE *) 0, 1 );
	}


/* link_machines - connect two machines together
 *
 * synopsis
 *
 *   new = link_machines( first, last );
 *
 *     new    - a machine constructed by connecting first to last
 *     first  - the machine whose successor is to be last
 *     last   - the machine whose predecessor is to be first
 *
 * note: this routine concatenates the machine first with the machine
 *  last to produce a machine new which will pattern-match first first
 *  and then last, and will fail if either of the sub-patterns fails.
 *  FIRST is set to new by the operation.  last is unmolested.
 */

int link_machines( first, last )
int first, last;
	{
	if ( first == NIL )
		return last;

	else if ( last == NIL )
		return first;

	else
		{
		mkxtion( finalst[first], last );
		finalst[first] = finalst[last];
		lastst[first] = MAX( lastst[first], lastst[last] );
		firstst[first] = MIN( firstst[first], firstst[last] );

		return first;
		}
	}


/* mark_beginning_as_normal - mark each "beginning" state in a machine
 *                            as being a "normal" (i.e., not trailing context-
 *                            associated) states
 *
 * The "beginning" states are the epsilon closure of the first state
 */

void mark_beginning_as_normal( mach )
register int mach;
	{
	switch ( state_type[mach] )
		{
		case STATE_NORMAL:
			/* Oh, we've already visited here. */
			return;

		case STATE_TRAILING_CONTEXT:
			state_type[mach] = STATE_NORMAL;

			if ( transchar[mach] == SYM_EPSILON )
				{
				if ( trans1[mach] != NO_TRANSITION )
					mark_beginning_as_normal(
						trans1[mach] );

				if ( trans2[mach] != NO_TRANSITION )
					mark_beginning_as_normal(
						trans2[mach] );
				}
			break;

		default:
			flexerror(
			_( "bad state type in mark_beginning_as_normal()" ) );
			break;
		}
	}


/* mkbranch - make a machine that branches to two machines
 *
 * synopsis
 *
 *   branch = mkbranch( first, second );
 *
 *     branch - a machine which matches either first's pattern or second's
 *     first, second - machines whose patterns are to be or'ed (the | operator)
 *
 * Note that first and second are NEITHER destroyed by the operation.  Also,
 * the resulting machine CANNOT be used with any other "mk" operation except
 * more mkbranch's.  Compare with mkor()
 */

int mkbranch( first, second )
int first, second;
	{
	int eps;

	if ( first == NO_TRANSITION )
		return second;

	else if ( second == NO_TRANSITION )
		return first;

	eps = mkstate( SYM_EPSILON );

	mkxtion( eps, first );
	mkxtion( eps, second );

	return eps;
	}


/* mkclos - convert a machine into a closure
 *
 * synopsis
 *   new = mkclos( state );
 *
 * new - a new state which matches the closure of "state"
 */

int mkclos( state )
int state;
	{
	return mkopt( mkposcl( state ) );
	}


/* mkopt - make a machine optional
 *
 * synopsis
 *
 *   new = mkopt( mach );
 *
 *     new  - a machine which optionally matches whatever mach matched
 *     mach - the machine to make optional
 *
 * notes:
 *     1. mach must be the last machine created
 *     2. mach is destroyed by the call
 */

int mkopt( mach )
int mach;
	{
	int eps;

	if ( ! SUPER_FREE_EPSILON(finalst[mach]) )
		{
		eps = mkstate( SYM_EPSILON );
		mach = link_machines( mach, eps );
		}

	/* Can't skimp on the following if FREE_EPSILON(mach) is true because
	 * some state interior to "mach" might point back to the beginning
	 * for a closure.
	 */
	eps = mkstate( SYM_EPSILON );
	mach = link_machines( eps, mach );

	mkxtion( mach, finalst[mach] );

	return mach;
	}


/* mkor - make a machine that matches either one of two machines
 *
 * synopsis
 *
 *   new = mkor( first, second );
 *
 *     new - a machine which matches either first's pattern or second's
 *     first, second - machines whose patterns are to be or'ed (the | operator)
 *
 * note that first and second are both destroyed by the operation
 * the code is rather convoluted because an attempt is made to minimize
 * the number of epsilon states needed
 */

int mkor( first, second )
int first, second;
	{
	int eps, orend;

	if ( first == NIL )
		return second;

	else if ( second == NIL )
		return first;

	else
		{
		/* See comment in mkopt() about why we can't use the first
		 * state of "first" or "second" if they satisfy "FREE_EPSILON".
		 */
		eps = mkstate( SYM_EPSILON );

		first = link_machines( eps, first );

		mkxtion( first, second );

		if ( SUPER_FREE_EPSILON(finalst[first]) &&
		     accptnum[finalst[first]] == NIL )
			{
			orend = finalst[first];
			mkxtion( finalst[second], orend );
			}

		else if ( SUPER_FREE_EPSILON(finalst[second]) &&
			  accptnum[finalst[second]] == NIL )
			{
			orend = finalst[second];
			mkxtion( finalst[first], orend );
			}

		else
			{
			eps = mkstate( SYM_EPSILON );

			first = link_machines( first, eps );
			orend = finalst[first];

			mkxtion( finalst[second], orend );
			}
		}

	finalst[first] = orend;
	return first;
	}


/* mkposcl - convert a machine into a positive closure
 *
 * synopsis
 *   new = mkposcl( state );
 *
 *    new - a machine matching the positive closure of "state"
 */

int mkposcl( state )
int state;
	{
	int eps;

	if ( SUPER_FREE_EPSILON(finalst[state]) )
		{
		mkxtion( finalst[state], state );
		return state;
		}

	else
		{
		eps = mkstate( SYM_EPSILON );
		mkxtion( eps, state );
		return link_machines( state, eps );
		}
	}


/* mkrep - make a replicated machine
 *
 * synopsis
 *   new = mkrep( mach, lb, ub );
 *
 *    new - a machine that matches whatever "mach" matched from "lb"
 *          number of times to "ub" number of times
 *
 * note
 *   if "ub" is INFINITY then "new" matches "lb" or more occurrences of "mach"
 */

int mkrep( mach, lb, ub )
int mach, lb, ub;
	{
	int base_mach, tail, copy, i;

	base_mach = copysingl( mach, lb - 1 );

	if ( ub == INFINITY )
		{
		copy = dupmachine( mach );
		mach = link_machines( mach,
		link_machines( base_mach, mkclos( copy ) ) );
		}

	else
		{
		tail = mkstate( SYM_EPSILON );

		for ( i = lb; i < ub; ++i )
			{
			copy = dupmachine( mach );
			tail = mkopt( link_machines( copy, tail ) );
			}

		mach = link_machines( mach, link_machines( base_mach, tail ) );
		}

	return mach;
	}


/* mkstate - create a state with a transition on a given symbol
 *
 * synopsis
 *
 *   state = mkstate( sym );
 *
 *     state - a new state matching sym
 *     sym   - the symbol the new state is to have an out-transition on
 *
 * note that this routine makes new states in ascending order through the
 * state array (and increments LASTNFA accordingly).  The routine DUPMACHINE
 * relies on machines being made in ascending order and that they are
 * CONTIGUOUS.  Change it and you will have to rewrite DUPMACHINE (kludge
 * that it admittedly is)
 */

int mkstate( sym )
int sym;
	{
	if ( ++lastnfa >= current_mns )
		{
		if ( (current_mns += MNS_INCREMENT) >= MAXIMUM_MNS )
			lerrif(
		_( "input rules are too complicated (>= %d NFA states)" ),
				current_mns );

		++num_reallocs;

		firstst = reallocate_integer_array( firstst, current_mns );
		lastst = reallocate_integer_array( lastst, current_mns );
		finalst = reallocate_integer_array( finalst, current_mns );
		transchar = reallocate_integer_array( transchar, current_mns );
		trans1 = reallocate_integer_array( trans1, current_mns );
		trans2 = reallocate_integer_array( trans2, current_mns );
		accptnum = reallocate_integer_array( accptnum, current_mns );
		assoc_rule =
			reallocate_integer_array( assoc_rule, current_mns );
		state_type =
			reallocate_integer_array( state_type, current_mns );
		}

	firstst[lastnfa] = lastnfa;
	finalst[lastnfa] = lastnfa;
	lastst[lastnfa] = lastnfa;
	transchar[lastnfa] = sym;
	trans1[lastnfa] = NO_TRANSITION;
	trans2[lastnfa] = NO_TRANSITION;
	accptnum[lastnfa] = NIL;
	assoc_rule[lastnfa] = num_rules;
	state_type[lastnfa] = current_state_type;

	/* Fix up equivalence classes base on this transition.  Note that any
	 * character which has its own transition gets its own equivalence
	 * class.  Thus only characters which are only in character classes
	 * have a chance at being in the same equivalence class.  E.g. "a|b"
	 * puts 'a' and 'b' into two different equivalence classes.  "[ab]"
	 * puts them in the same equivalence class (barring other differences
	 * elsewhere in the input).
	 */

	if ( sym < 0 )
		{
		/* We don't have to update the equivalence classes since
		 * that was already done when the ccl was created for the
		 * first time.
		 */
		}

	else if ( sym == SYM_EPSILON )
		++numeps;

	else
		{
		check_char( sym );

		if ( useecs )
			/* Map NUL's to csize. */
			mkechar( sym ? sym : csize, nextecm, ecgroup );
		}

	return lastnfa;
	}


/* mkxtion - make a transition from one state to another
 *
 * synopsis
 *
 *   mkxtion( statefrom, stateto );
 *
 *     statefrom - the state from which the transition is to be made
 *     stateto   - the state to which the transition is to be made
 */

void mkxtion( statefrom, stateto )
int statefrom, stateto;
	{
	if ( trans1[statefrom] == NO_TRANSITION )
		trans1[statefrom] = stateto;

	else if ( (transchar[statefrom] != SYM_EPSILON) ||
		  (trans2[statefrom] != NO_TRANSITION) )
		flexfatal( _( "found too many transitions in mkxtion()" ) );

	else
		{ /* second out-transition for an epsilon state */
		++eps2;
		trans2[statefrom] = stateto;
		}
	}

/* new_rule - initialize for a new rule */

void new_rule()
	{
	if ( ++num_rules >= current_max_rules )
		{
		++num_reallocs;
		current_max_rules += MAX_RULES_INCREMENT;
		rule_type = reallocate_integer_array( rule_type,
							current_max_rules );
		rule_linenum = reallocate_integer_array( rule_linenum,
							current_max_rules );
		rule_useful = reallocate_integer_array( rule_useful,
							current_max_rules );
		}

	if ( num_rules > MAX_RULE )
		lerrif( _( "too many rules (> %d)!" ), MAX_RULE );

	rule_linenum[num_rules] = linenum;
	rule_useful[num_rules] = false;
	}
OpenPOWER on IntegriCloud