-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathio.c
1374 lines (1210 loc) · 30.2 KB
/
io.c
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
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
#include "Header.h"
#include "Order.h"
#include "List.h"
#include "Symbols.h"
#include "Io.h"
/* Default is "x+y"; define OUTPUT_SPACE for "x + y". */
#define OUTPUT_SPACE
/* Token types */
#define OPEN_PAREN 1
#define OTHER_PUNC 2
#define NAME_SYM 6
#define SYM_SYM 7
/* Following structure is to store data on symbol that might be special op. */
struct sequence_member {
Term_ptr t;
short binary_type;
short binary_prec;
short unary_type;
short unary_prec;
};
/* The following declarations are for mutually recursive routines. */
Term_ptr seq_to_term(struct sequence_member *seq,int start,int end,int m);
Term_ptr str_to_term(char *buf, int *p, int in_list);
/*************
*
* int is_alpha_numeric(c) -- including _ and $
*
*************/
static int is_alpha_numeric(char c)
{
return((c >= '0' && c <= '9') ||
(c >= 'a' && c <= 'z') ||
(c >= 'A' && c <= 'Z') ||
c == '_' ||
c == '$');
} /* is_alpha_numeric */
/*************
*
* int name_sym(s)
*
*************/
static int name_sym(char *s)
{
if (*s == '\'' || *s == '\"')
return(1); /* quoted string ok */
else {
for ( ; *s; s++)
if (!is_alpha_numeric(*s))
return(0);
return(1);
}
} /* name_sym */
/*************
*
* int is_white(c) -- including start-of-comment '%'.
*
*************/
static int is_white(char c)
{
return(c == ' ' ||
c == '\t' || /* tab */
c == '\n' || /* newline */
c == '\v' || /* vertical tab */
c == '\r' || /* carriage return */
c == '\f' || /* form feed */
c == '%');
} /* is_white */
/*************
*
* skip_white(buffer, position)
*
* Advance the pointer to the next nonwhite, noncomment position.
*
*************/
static void skip_white(char *buf, int *p)
{
char c;
c = buf[*p];
while (is_white(c)) {
if (c == '%') /* skip over comment */
while (buf[++(*p)] != '\n') ;
c = buf[++(*p)];
}
} /* skip_white */
/*************
*
* int is_symbol_char(c, in_list)
*
*************/
static int is_symbol_char(char c, int in_list)
{
return(c == '+' ||
c == '-' ||
c == '*' ||
c == '/' ||
c == '\\' ||
c == '^' ||
c == '<' ||
c == '>' ||
c == '=' ||
c == '`' ||
c == '~' ||
c == ':' ||
c == '?' ||
c == '@' ||
c == '&' ||
(c == '|' && !in_list) ||
c == '!' ||
c == '#' ||
c == ';' );
} /* is_symbol_char */
/****************************************
write_term outputs a term in readable format (w.r.t. infix, prefix,
and postfix operators) and without extra parentheses. It it much
complicated by one feature: deciding where to omit space around
the special operators. For example, just as we can input a+b+c
instead of a + b + c, we wish to output without spaces were possible.
(I'm sorry the code is so complicated---I couldn't see a simpler way
of doing it.)
There are 2 types of constant/operator/functor:
NAME_SYM: string of alphanumerics, $, and _. Also quoted string.
SYM_SYM: string of *+-/\^<>=`~:?@&!;# and sometimes | (if not in list)
For completeness, the other characters are
,()[]{} and sometimes | (if in list) puctuation for building terms
. end of input term
% start of comment
"' for quoted strings
For this problem, tokens are of 4 types:
NAME_SYM
SYM_SYM
OPEN_PAREN '('
OTHER_PUNC other punctuation (including space)
Special ops that are NAME_SYMs are always surrounded by spaces.
Here are the space rules for SYM_SYM special ops:
infix
omit space before if preceding token is NAME_SYM or OTHER_PUNC
omit space after if next token is is NAME_SYM or OTHER_PUNC
(note that space is included if next is '(')
prefix
omit space before if preceding token is OTHER_PUNC
omit space after if next token is is NAME_SYM or OTHER_PUNC
postfix
omit space before if preceding token is NAME_SYM or OTHER_PUNC
always include space after (could omit if next token is OTHER_PUNC,
but current mechanism won't handle that, and it's not
that important)
*****************************************/
/*************
*
* int next_token_type(t, n)
*
* Find the next token type that would be output for t.
* n is precedence parameter as in write term.
*
*************/
static int next_token_type(Term_ptr t, int n)
{
struct sym_ent *s;
int na1;
char *str;
if (VARIABLE(t))
return(NAME_SYM);
else if (t->arity == 0) {
str = sn_to_str(t->symbol);
if (str_ident(str, "$nil"))
return(OTHER_PUNC);
else
return(name_sym(str) ? NAME_SYM : SYM_SYM);
}
else { /* complex */
str = sn_to_str(t->symbol);
if (str_ident(str, "$cons") && t->arity == 2)
return(OTHER_PUNC);
else if (str_ident(str, "$Quantified")) {
/* parens if parent is special op */
if (n < 1000)
return(OPEN_PAREN);
else
return(next_token_type(t->args[0], 0));
}
else {
s = sn_to_node(t->symbol);
if (s->special_op && s->arity == 2) {
na1 = s->op_prec;
if (s->op_type == XFX || s->op_type == XFY)
na1--;
if (s->op_prec > n)
return(OPEN_PAREN);
else
return(next_token_type(t->args[0], na1));
}
else if (s->special_op && s->arity == 1) {
na1 = s->op_prec;
if (s->op_type == FX || s->op_type == XF)
na1--;
if (s->op_prec > n)
return(OPEN_PAREN);
if (s->op_type == FX || s->op_type == FY)
return(name_sym(str) ? NAME_SYM : SYM_SYM);
else
return(next_token_type(t->args[0], na1));
}
else
return(name_sym(str) ? NAME_SYM : SYM_SYM);
}
}
} /* next_token_type */
/*************
*
* write_term(file_ptr, term, n, prev) -- print in readable form.
*
*************/
void write_term(FILE *fp, Term_ptr t, int n, int *prev)
{
Term_ptr t1;
struct sym_ent *s;
int na1, na2, next;
char *str, *s1, *s2;
if (!t) {
fprintf(fp, "<write_term gets NULL pointer>");
return;
}
if (VARIABLE(t)) {
print_variable(fp, t);
*prev = NAME_SYM;
}
else if (t->arity == 0) {
str = sn_to_str(t->symbol);
if (str_ident(str, "$nil")) {
fprintf(fp, "[]");
*prev = OTHER_PUNC;
}
else {
fprintf(fp, "%s", str);
*prev = (name_sym(str) ? NAME_SYM : SYM_SYM);
}
}
else { /* complex */
str = sn_to_str(t->symbol);
if (str_ident(str, "$Quantified")) { /* Quantified Formula */
int i;
/* parens if parent is special op */
if (n < 1000) {
fprintf(fp, "("); *prev = OPEN_PAREN;
}
for (i = 0; i < t->arity; i++) {
/* parens if special op in child */
write_term(fp, t->args[i], 0, prev);
if (i != t->arity-1) {
fprintf(fp, " "); *prev = OTHER_PUNC;
}
}
if (n < 1000) {
fprintf(fp, ")"); *prev = OTHER_PUNC;
}
} /* end Formula */
else if (is_symbol(t->symbol, "$cons", 2)) {
fprintf(fp, "["); *prev = OTHER_PUNC;
write_term(fp, t->args[0], 1000, prev);
t1 = t->args[1];
while (t1->symbol == str_to_sn("$cons", 2)) {
fprintf(fp, ","); *prev = OTHER_PUNC;
write_term(fp, t1->args[0], 1000, prev);
t1 = t1->args[1];
}
if (t1->symbol == str_to_sn("$nil", 0)) {
fprintf(fp, "]"); *prev = OTHER_PUNC;
}
else {
fprintf(fp, "|"); *prev = OTHER_PUNC;
write_term(fp, t1, 1000, prev);
fprintf(fp, "]"); *prev = OTHER_PUNC;
}
} /* end list */
else {
s = sn_to_node(t->symbol);
if (s->special_op && s->arity == 2) { /* infix */
na1 = na2 = s->op_prec;
if (s->op_type == XFX || s->op_type == XFY)
na1--;
if (s->op_type == XFX || s->op_type == YFX)
na2--;
if (s->op_prec > n) {
fprintf(fp, "("); *prev = OPEN_PAREN;
}
write_term(fp, t->args[0], na1, prev);
/* Decide on spaces around infix op. */
#ifdef OUTPUT_SPACE
s1 = s2 = " ";
#else
if (name_sym(str))
s1 = s2 = " ";
else {
if (*prev == OTHER_PUNC || *prev == NAME_SYM)
s1 = "";
else
s1 = " ";
next = next_token_type(t->args[1], na2);
if (next == OTHER_PUNC || next == NAME_SYM)
s2 = "";
else
s2 = " ";
}
#endif
fprintf(fp, "%s%s%s", s1,str,s2);
if (str_ident(s2, " "))
*prev = OTHER_PUNC;
else
*prev = (name_sym(str) ? NAME_SYM : SYM_SYM);
write_term(fp, t->args[1], na2, prev);
if (s->op_prec > n) {
fprintf(fp, ")"); *prev = OTHER_PUNC;
}
}
else if (s->special_op && s->arity == 1) { /* prefix,postfix */
na1 = s->op_prec;
if (s->op_type == FX || s->op_type == XF)
na1--;
if (s->op_prec > n) {
fprintf(fp, "("); *prev = OPEN_PAREN;
}
if (s->op_type == FX || s->op_type == FY) {
/* Decide on spaces around special prefix op. */
if (name_sym(str))
s1 = s2 = " ";
else {
if (*prev == OTHER_PUNC || *prev == OPEN_PAREN)
s1 = "";
else
s1 = " ";
next = next_token_type(t->args[0], na1);
if (next == OTHER_PUNC || next == OPEN_PAREN || next == NAME_SYM)
s2 = "";
else
s2 = " ";
}
fprintf(fp, "%s%s%s", s1,str,s2);
if (str_ident(s2, " "))
*prev = OTHER_PUNC;
else
*prev = (name_sym(str) ? NAME_SYM : SYM_SYM);
write_term(fp, t->args[0], na1, prev);
}
else {
write_term(fp, t->args[0], na1, prev);
/* Decide on spaces around special postfix op. */
if (name_sym(str))
s1 = s2 = " ";
else {
if (*prev == OTHER_PUNC || *prev == NAME_SYM)
s1 = "";
else
s1 = " ";
/* Can't easily tell next token, so just output space. */
s2 = " ";
}
fprintf(fp, "%s%s%s", s1,str,s2);
*prev = OTHER_PUNC;
}
if (s->op_prec > n) {
fprintf(fp, ")"); *prev = OTHER_PUNC;
}
}
else { /* functor(args) */
int i;
fprintf(fp, "%s", str);
fprintf(fp, "("); *prev = OPEN_PAREN;
for (i = 0; i < t->arity; i++) {
write_term(fp, t->args[i], 1000, prev);
if (i != t->arity-1) {
fprintf(fp, ","); *prev = OTHER_PUNC;
}
}
fprintf(fp, ")"); *prev = OTHER_PUNC;
}
}
}
} /* write_term */
/*************
*
* display_term(file_ptr, term) -- Display a term in internal form.
*
*************/
void display_term(FILE *fp, Term_ptr t)
{
if (!t)
fprintf(fp, "<display_term gets NULL pointer>");
else if (VARIABLE(t))
print_variable(fp, t);
else {
fprintf(fp, "%s", sn_to_str(t->symbol));
if (t->arity > 0) {
int i;
fprintf(fp, "(");
for (i = 0; i < t->arity; i++) {
display_term(fp, t->args[i]);
if (i != t->arity-1)
fprintf(fp, ",");
}
fprintf(fp, ")");
}
}
} /* display_term */
/*************
*
* d_term(term) -- display_term and \n to the standard output.
*
*************/
void d_term(Term_ptr t)
{
display_term(stdout, t);
printf("\n");
fflush(stdout);
} /* p_term */
/*************
*
* print_term(file_ptr, term) -- Print a term to a file.
*
* Flag determines write_term vs. display_term.
*
*************/
void print_term(FILE *fp, Term_ptr t)
{
int i;
if (Flags[DISPLAY_TERMS].val)
display_term(fp, t);
else {
i = OTHER_PUNC; /* Assume previous token is punctuation. */
write_term(fp, t, 1000, &i);
}
} /* print_term */
/*************
*
* p_term(term) -- print_term and \n to the standard output.
*
*************/
void p_term(Term_ptr t)
{
print_term(stdout, t);
printf("\n");
fflush(stdout);
} /* p_term */
/*************
*
* print_term_nl(fp, term) -- print_term followed by period and newline
*
*************/
void print_term_nl(FILE *fp, Term_ptr t)
{
print_term(fp, t);
fprintf(fp,".\n");
} /* print_term_nl */
/*************
*
* print_variable(fp, variable)
*
*************/
void print_variable(FILE *fp, Term_ptr t)
{
int i;
if (Flags[PROLOG_STYLE_VARIABLES].val) {
fprintf(fp, "%c", (t->symbol % 26) + 'A');
i = t->symbol / 26;
if (i > 0)
fprintf(fp, "%d", i);
}
else {
if (t->symbol <= 2)
fprintf(fp, "%c", 'x'+t->symbol);
else if (t->symbol <= 5)
fprintf(fp, "%c", 'r'+t->symbol);
else
fprintf(fp, "%c%d", 'v', t->symbol);
}
} /* print_variable */
/*************
*
* void fill_in_op_data(p, t)
*
*************/
static void fill_in_op_data(struct sequence_member *p, Term_ptr t)
{
struct sym_ent *nd;
char *str;
p->t = t;
p->binary_type = p->unary_type = 0;
p->binary_prec = p->unary_prec = 0;
if (t->arity == 0) {
str = sn_to_str(t->symbol);
nd = find_special_nd(str, 1);
if (nd) {
p->unary_type = nd->op_type;
p->unary_prec = nd->op_prec;
}
nd = find_special_nd(str, 2);
if (nd) {
p->binary_type = nd->op_type;
p->binary_prec = nd->op_prec;
}
}
} /* fill_in_op_data */
/*************
*
* get_name(buffer, position, name, in_list)
*
*************/
static void get_name(char *buf, int *p, char *name, int in_list)
{
int i, ok, okq;
char c, q;
i = 0; ok = 1; okq = 1;
skip_white(buf, p);
c = buf[*p];
if (is_alpha_numeric(c)) {
while ((ok = i < MAX_NAME-1) && is_alpha_numeric(c)) {
name[i++] = c;
c = buf[++(*p)];
}
}
else if (is_symbol_char(c, in_list)) {
while ((ok = i < MAX_NAME-1) && is_symbol_char(c, in_list)) {
name[i++] = c;
c = buf[++(*p)];
}
}
else if (c == '\'' || c == '\"') {
q = c;
name[i++] = c;
c = buf[++(*p)];
while ((ok = i < MAX_NAME-1) && c != q && (okq = c != '\0')) {
name[i++] = c;
c = buf[++(*p)];
}
if (okq) {
name[i++] = c; /* quote char */
++(*p);
}
}
if (!ok) {
fprintf(stdout, "\nERROR, name too big, max is %d; ", MAX_NAME-1);
name[0] = '\0';
}
else if (!okq) {
fprintf(stdout, "\nERROR, quoted name has no end; ");
name[0] = '\0';
}
else
name[i] = '\0';
} /* get_name */
/*************
*
* print_error(fp, buf, pos)
*
*************/
static void print_error(FILE *fp, char *buf, int pos)
{
#if 0
int i;
fprintf(fp, "%s\n", buf);
for (i = 0; i < pos; i++) {
if (buf[i] == '\t')
fprintf(fp, "--------"); /* doesn't always work */
else if (buf[i] == '\n')
fprintf(fp, "\n");
else
fprintf(fp, "-");
}
fprintf(fp, "^\n");
#else
int i;
i = 0;
if (buf[0] == '\n')
i = 1;
while (i < pos) {
if (buf[i] == '%') /* skip over comment */
while (buf[++i] != '\n') ;
fprintf(fp, "%c", buf[i++]);
}
fprintf(fp, " ***HERE*** ");
while (buf[i]) {
if (buf[i] == '%') /* skip over comment */
while (buf[++i] != '\n') ;
fprintf(fp, "%c", buf[i++]);
}
fprintf(fp, "\n");
#endif
} /* print_error */
/*************
*
* Term_ptr seq_to_quant_term(seq, n)
*
* Take a sequence of terms t1,...,tn and build term $Quantified(t1,...,tn).
* t1 is already known to be a quantifier, and n >= 3.
* Check that t2,...,tn-1 are all names.
* On success, the resulting term is an entirely new copy.
*
*************/
static Term_ptr seq_to_quant_term(struct sequence_member *seq, int n)
{
Term_ptr t;
int i;
if (n == 1)
return(NULL);
for (i = 1; i < n-1; i++)
if (seq[i].t->arity != 0)
return(NULL);
/* Special case: negated formula need not be parenthesized.
* For example, all x -p(x) is OK. In this case, the sequence is
* [all, x, -, p(x)], so we must adjust things.
*/
if (str_ident(sn_to_str(seq[n-2].t->symbol), "-")) {
if (n == 3)
return(NULL); /* all - p */
else {
Term_ptr t;
t = seq_to_term(seq, n-2, n-1, 1000);
printf("adjusted term: "); p_term(t);
if (t) {
zap_term(seq[n-2].t);
zap_term(seq[n-1].t);
fill_in_op_data(&seq[n-2], t);
/* caller will still think there are n terms */
seq[n-1].t = NULL;
n--;
}
else
return(NULL);
}
}
t = get_term(n);
t->symbol = str_to_sn("$Quantified", n);
for (i = 0; i < n; i++)
t->args[i] = copy_term(seq[i].t);
return(t);
} /* seq_to_quant_term */
/*************
*
* Term_ptr seq_to_term(seq, start, end, m)
*
* seq is an array of terms/operators, and start and end are
* indexes into seq. This routine attempts to construct a term
* starting with start, ending with end, with precedence <= m.
* On success, the resulting term is an entirely new copy.
*
*************/
Term_ptr seq_to_term(struct sequence_member *seq, int start, int end, int m)
{
int i, n, type;
Term_ptr t1, t2, t3, t;
if (start == end) {
t = copy_term(seq[start].t);
return(t);
}
else {
/* Check if first is prefix op that applies to rest. */
if (seq[start].t->arity == 0) {
type = seq[start].unary_type;
n = seq[start].unary_prec;
t = seq[start].t;
if (type == FX && n <= m) {
t1 = seq_to_term(seq, start+1, end, n-1);
if (t1) {
t3 = get_term(1);
t3->symbol = str_to_sn(sn_to_str(t->symbol), 1);
t3->args[0] = t1;
return(t3);
}
}
else if (type == FY && n <= m) {
t1 = seq_to_term(seq, start+1, end, n);
if (t1) {
t3 = get_term(1);
t3->symbol = str_to_sn(sn_to_str(t->symbol), 1);
t3->args[0] = t1;
return(t3);
}
}
}
/* Check if last is postfix op that applies to all preceding. */
if (seq[end].t->arity == 0) {
type = seq[end].unary_type;
n = seq[end].unary_prec;
t = seq[end].t;
if (type == XF && n <= m) {
t1 = seq_to_term(seq, start, end-1, n-1);
if (t1) {
t3 = get_term(1);
t3->symbol = str_to_sn(sn_to_str(t->symbol), 1);
t3->args[0] = t1;
return(t3);
}
}
else if (type == YF && n <= m) {
t1 = seq_to_term(seq, start, end-1, n);
if (t1) {
t3 = get_term(1);
t3->symbol = str_to_sn(sn_to_str(t->symbol), 1);
t3->args[0] = t1;
return(t3);
}
}
}
/* Look for an infix operator. */
for (i = start+1; i <= end-1; i++) {
if (seq[i].t->arity == 0) {
type = seq[i].binary_type;
n = seq[i].binary_prec;
t = seq[i].t;
if (type == XFY && n <= m) {
t1 = seq_to_term(seq, start, i-1, n-1);
if (t1) {
t2 = seq_to_term(seq, i+1, end, n);
if (!t2)
zap_term(t1);
}
if (t1 && t2) {
t3 = get_term(2);
t3->symbol = str_to_sn(sn_to_str(t->symbol), 2);
t3->args[0] = t1;
t3->args[1] = t2;
return(t3);
}
}
else if (type == YFX && n <= m) {
t2 = seq_to_term(seq, i+1, end, n-1);
if (t2) {
t1 = seq_to_term(seq, start, i-1, n);
if (!t1)
zap_term(t2);
}
if (t1 && t2) {
t3 = get_term(2);
t3->symbol = str_to_sn(sn_to_str(t->symbol), 2);
t3->args[0] = t1;
t3->args[1] = t2;
return(t3);
}
}
else if (type == XFX && n <= m) {
t1 = seq_to_term(seq, start, i-1, n-1);
if (t1) {
t2 = seq_to_term(seq, i+1, end, n-1);
if (!t2)
zap_term(t1);
}
if (t1 && t2) {
t3 = get_term(2);
t3->symbol = str_to_sn(sn_to_str(t->symbol), 2);
t3->args[0] = t1;
t3->args[1] = t2;
return(t3);
}
}
} /* name */
} /* loop looking for infix op to apply */
return(NULL);
}
} /* seq_to_term */
/*************
*
* struct term_ptr *str_to_args(buffer, position, name)
*
* name -- the functor.
*
* start: functor( a1 , a2 , a3 )
* ^
* end: functor( a1 , a2 , a3 )
* ^
*************/
static Term_ptr str_to_args(char *buf, int *p, char *name)
{
Term_ptr t, t_sub;
Gen_ptr_ptr p0, p1, p2;
int i, n;
p0 = NULL;
n = 0; /* count subterms to get arity */
while (buf[*p] != ')') {
n++;
t_sub = str_to_term(buf, p, 0);
if (!t_sub)
return(NULL);
else if (buf[*p] != ',' && buf[*p] != ')') {
fprintf(stdout, "\nERROR, comma or ) expected:\n");
print_error(stdout, buf, *p);
return(NULL);
}
else {
p2 = get_gen_ptr();
p2->u.t = t_sub;
if (p0)
p1->next = p2;
else
p0 = p2;
p1 = p2;
if (buf[*p] == ',')
(*p)++; /* step past comma */
}
}
if (n == 0) {
fprintf(stdout, "\nERROR, functor has no arguments:\n");
print_error(stdout, buf, *p);
return(NULL);
}
t = get_term(n);
t->symbol = str_to_sn(name, n);
for (i = 0; i < t->arity; i++) {
t->args[i] = p0->u.t;
p2 = p0;
p0 = p0->next;
free_gen_ptr(p2);
}
return(t);
} /* str_to_args */
/*************
*
* struct term_ptr *str_to_list(buffer, position)
*
* start: [ a1 , a2 , a3 ]
* ^
* end: [ a1 , a2 , a3 ]
* ^
*************/
static Term_ptr str_to_list(char *buf, int *p)
{
Term_ptr t_cons, t_head, t_tail, t_return, t_prev;
int go;
(*p)++; /* step past '[' */
if (buf[*p] == ']') { /* [] */
t_return = get_term(0);
t_return->symbol = str_to_sn("$nil", 0);
(*p)++; /* skip "]" */
return(t_return);
}
else { /* [h|t], [t1,...,tn], or [t1,...,tn|t] */
t_prev = NULL;
go = 1;
while (go) {
t_head = str_to_term(buf, p, 1);
if (!t_head)
return(NULL); /* error */
t_cons = get_term(2);
if (t_prev)
t_prev->args[1] = t_cons;
else
t_return = t_cons;
t_cons->symbol = str_to_sn("$cons", 2);
t_cons->args[0] = t_head;
t_prev = t_cons;
go = (buf[*p] == ',');
if (go)
(*p)++; /* step past ',' */
}
if (buf[*p] == ']') {
t_tail = get_term(0);
t_prev->args[1] = t_tail;
t_tail->symbol = str_to_sn("$nil", 0);
(*p)++; /* step past ']' */
return(t_return);
}
else if (buf[*p] == '|') {
(*p)++; /* step past '|' */
t_tail = str_to_term(buf, p, 1);
if (buf[*p] != ']') {
fprintf(stdout, "\nERROR, ']' expected in list:\n");
print_error(stdout, buf, *p);
return(NULL);
}
t_prev->args[1] = t_tail;
(*p)++; /* step past ']' */
return(t_return);
}
else {
fprintf(stdout, "\nERROR, ], |, or comma expected in list:\n");
print_error(stdout, buf, *p);
return(NULL);
}
}
} /* str_to_list */