expr.y revision 96382 
1%{
2/* Written by Pace Willisson (pace@blitz.com)
3 * and placed in the public domain.
4 *
5 * Largely rewritten by J.T. Conklin (jtc@wimsey.com)
6 *
7 * $FreeBSD: head/bin/expr/expr.y 96382 2002-05-11 03:08:12Z wollman $
8 */
9
10#include <sys/types.h>
11
12#include <ctype.h>
13#include <err.h>
14#include <errno.h>
15#include <inttypes.h>
16#include <limits.h>
17#include <locale.h>
18#include <stdio.h>
19#include <stdlib.h>
20#include <string.h>
21#include <regex.h>
22#include <unistd.h>
23
24/*
25 * POSIX specifies a specific error code for syntax errors.  We exit
26 * with this code for all errors.
27 */
28#define	ERR_EXIT	2
29
30enum valtype {
31	integer, numeric_string, string
32} ;
33
34struct val {
35	enum valtype type;
36	union {
37		char *s;
38		intmax_t i;
39	} u;
40} ;
41
42struct val *result;
43
44int		chk_div(intmax_t, intmax_t);
45int		chk_minus(intmax_t, intmax_t, intmax_t);
46int		chk_plus(intmax_t, intmax_t, intmax_t);
47int		chk_times(intmax_t, intmax_t, intmax_t);
48void		free_value(struct val *);
49int		is_zero_or_null(struct val *);
50int		isstring(struct val *);
51struct val	*make_integer(intmax_t);
52struct val	*make_str(const char *);
53struct val	*op_and(struct val *, struct val *);
54struct val	*op_colon(struct val *, struct val *);
55struct val	*op_div(struct val *, struct val *);
56struct val	*op_eq(struct val *, struct val *);
57struct val	*op_ge(struct val *, struct val *);
58struct val	*op_gt(struct val *, struct val *);
59struct val	*op_le(struct val *, struct val *);
60struct val	*op_lt(struct val *, struct val *);
61struct val	*op_minus(struct val *, struct val *);
62struct val	*op_ne(struct val *, struct val *);
63struct val	*op_or(struct val *, struct val *);
64struct val	*op_plus(struct val *, struct val *);
65struct val	*op_rem(struct val *, struct val *);
66struct val	*op_times(struct val *, struct val *);
67intmax_t	to_integer(struct val *);
68void		to_string(struct val *);
69int		yyerror(const char *);
70int		yylex(void);
71int		yyparse(void);
72
73static int	eflag;
74char **av;
75%}
76
77%union
78{
79	struct val *val;
80}
81
82%left <val> '|'
83%left <val> '&'
84%left <val> '=' '>' '<' GE LE NE
85%left <val> '+' '-'
86%left <val> '*' '/' '%'
87%left <val> ':'
88
89%token <val> TOKEN
90%type <val> start expr
91
92%%
93
94start: expr { result = $$; }
95
96expr:	TOKEN
97	| '(' expr ')' { $$ = $2; }
98	| expr '|' expr { $$ = op_or ($1, $3); }
99	| expr '&' expr { $$ = op_and ($1, $3); }
100	| expr '=' expr { $$ = op_eq ($1, $3); }
101	| expr '>' expr { $$ = op_gt ($1, $3); }
102	| expr '<' expr { $$ = op_lt ($1, $3); }
103	| expr GE expr  { $$ = op_ge ($1, $3); }
104	| expr LE expr  { $$ = op_le ($1, $3); }
105	| expr NE expr  { $$ = op_ne ($1, $3); }
106	| expr '+' expr { $$ = op_plus ($1, $3); }
107	| expr '-' expr { $$ = op_minus ($1, $3); }
108	| expr '*' expr { $$ = op_times ($1, $3); }
109	| expr '/' expr { $$ = op_div ($1, $3); }
110	| expr '%' expr { $$ = op_rem ($1, $3); }
111	| expr ':' expr { $$ = op_colon ($1, $3); }
112	;
113
114
115%%
116
117struct val *
118make_integer(intmax_t i)
119{
120	struct val *vp;
121
122	vp = (struct val *) malloc (sizeof (*vp));
123	if (vp == NULL) {
124		errx(ERR_EXIT, "malloc() failed");
125	}
126
127	vp->type = integer;
128	vp->u.i  = i;
129	return vp;
130}
131
132struct val *
133make_str(const char *s)
134{
135	struct val *vp;
136	char *ep;
137
138	vp = (struct val *) malloc (sizeof (*vp));
139	if (vp == NULL || ((vp->u.s = strdup (s)) == NULL)) {
140		errx(ERR_EXIT, "malloc() failed");
141	}
142
143	/*
144	 * Previously we tried to scan the string to see if it ``looked like''
145	 * an integer (erroneously, as it happened).  Let strtoimax() do the
146	 * dirty work.  We could cache the value, except that we are using
147	 * a union and need to preserve the original string form until we
148	 * are certain that it is not needed.
149	 *
150	 * IEEE Std.1003.1-2001 says:
151	 * /integer/ An argument consisting only of an (optional) unary minus
152	 *	     followed by digits.
153	 *
154	 * This means that arguments which consist of digits followed by
155	 * non-digits MUST NOT be considered integers.  strtoimax() will
156	 * figure this out for us.
157	 */
158	if (eflag)
159		(void)strtoimax(s, &ep, 10);
160	else
161		(void)strtol(s, &ep, 10);
162
163	if (*ep != '\0')
164		vp->type = string;
165	else
166		vp->type = numeric_string;
167
168	return vp;
169}
170
171
172void
173free_value(struct val *vp)
174{
175	if (vp->type == string || vp->type == numeric_string)
176		free (vp->u.s);
177}
178
179
180intmax_t
181to_integer(struct val *vp)
182{
183	intmax_t i;
184
185	if (vp->type == integer)
186		return 1;
187
188	if (vp->type == string)
189		return 0;
190
191	/* vp->type == numeric_string, make it numeric */
192	errno = 0;
193	if (eflag) {
194		i  = strtoimax(vp->u.s, (char **)NULL, 10);
195		if (errno == ERANGE)
196			err(ERR_EXIT, NULL);
197	} else {
198		i = strtol(vp->u.s, (char **)NULL, 10);
199	}
200
201	free (vp->u.s);
202	vp->u.i = i;
203	vp->type = integer;
204	return 1;
205}
206
207void
208to_string(struct val *vp)
209{
210	char *tmp;
211
212	if (vp->type == string || vp->type == numeric_string)
213		return;
214
215	/*
216	 * log_10(x) ~= 0.3 * log_2(x).  Rounding up gives the number
217	 * of digits; add one each for the sign and terminating null
218	 * character, respectively.
219	 */
220#define	NDIGITS(x) (3 * (sizeof(x) * CHAR_BIT) / 10 + 1 + 1 + 1)
221	tmp = malloc(NDIGITS(vp->u.i));
222	if (tmp == NULL)
223		errx(ERR_EXIT, "malloc() failed");
224
225	sprintf(tmp, "%jd", vp->u.i);
226	vp->type = string;
227	vp->u.s  = tmp;
228}
229
230
231int
232isstring(struct val *vp)
233{
234	/* only TRUE if this string is not a valid integer */
235	return (vp->type == string);
236}
237
238
239int
240yylex(void)
241{
242	char *p;
243
244	if (*av == NULL)
245		return (0);
246
247	p = *av++;
248
249	if (strlen (p) == 1) {
250		if (strchr ("|&=<>+-*/%:()", *p))
251			return (*p);
252	} else if (strlen (p) == 2 && p[1] == '=') {
253		switch (*p) {
254		case '>': return (GE);
255		case '<': return (LE);
256		case '!': return (NE);
257		}
258	}
259
260	yylval.val = make_str (p);
261	return (TOKEN);
262}
263
264int
265is_zero_or_null(struct val *vp)
266{
267	if (vp->type == integer) {
268		return (vp->u.i == 0);
269	} else {
270		return (*vp->u.s == 0 || (to_integer (vp) && vp->u.i == 0));
271	}
272	/* NOTREACHED */
273}
274
275int
276main(int argc, char *argv[])
277{
278	int c;
279
280	setlocale (LC_ALL, "");
281	if (getenv("EXPR_COMPAT") != NULL) {
282		av = argv + 1;
283		eflag = 1;
284	} else {
285		while ((c = getopt(argc, argv, "e")) != -1)
286			switch (c) {
287			case 'e':
288				eflag = 1;
289				break;
290
291			default:
292				fprintf(stderr,
293				    "usage: expr [-e] expression\n");
294				exit(ERR_EXIT);
295			}
296		av = argv + optind;
297	}
298
299	yyparse();
300
301	if (result->type == integer)
302		printf("%jd\n", result->u.i);
303	else
304		printf("%s\n", result->u.s);
305
306	return (is_zero_or_null(result));
307}
308
309int
310yyerror(const char *s __unused)
311{
312	errx(ERR_EXIT, "syntax error");
313}
314
315
316struct val *
317op_or(struct val *a, struct val *b)
318{
319	if (is_zero_or_null (a)) {
320		free_value (a);
321		return (b);
322	} else {
323		free_value (b);
324		return (a);
325	}
326}
327
328struct val *
329op_and(struct val *a, struct val *b)
330{
331	if (is_zero_or_null (a) || is_zero_or_null (b)) {
332		free_value (a);
333		free_value (b);
334		return (make_integer ((intmax_t)0));
335	} else {
336		free_value (b);
337		return (a);
338	}
339}
340
341struct val *
342op_eq(struct val *a, struct val *b)
343{
344	struct val *r;
345
346	if (isstring (a) || isstring (b)) {
347		to_string (a);
348		to_string (b);
349		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) == 0));
350	} else {
351		(void)to_integer(a);
352		(void)to_integer(b);
353		r = make_integer ((intmax_t)(a->u.i == b->u.i));
354	}
355
356	free_value (a);
357	free_value (b);
358	return r;
359}
360
361struct val *
362op_gt(struct val *a, struct val *b)
363{
364	struct val *r;
365
366	if (isstring (a) || isstring (b)) {
367		to_string (a);
368		to_string (b);
369		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) > 0));
370	} else {
371		(void)to_integer(a);
372		(void)to_integer(b);
373		r = make_integer ((intmax_t)(a->u.i > b->u.i));
374	}
375
376	free_value (a);
377	free_value (b);
378	return r;
379}
380
381struct val *
382op_lt(struct val *a, struct val *b)
383{
384	struct val *r;
385
386	if (isstring (a) || isstring (b)) {
387		to_string (a);
388		to_string (b);
389		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) < 0));
390	} else {
391		(void)to_integer(a);
392		(void)to_integer(b);
393		r = make_integer ((intmax_t)(a->u.i < b->u.i));
394	}
395
396	free_value (a);
397	free_value (b);
398	return r;
399}
400
401struct val *
402op_ge(struct val *a, struct val *b)
403{
404	struct val *r;
405
406	if (isstring (a) || isstring (b)) {
407		to_string (a);
408		to_string (b);
409		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) >= 0));
410	} else {
411		(void)to_integer(a);
412		(void)to_integer(b);
413		r = make_integer ((intmax_t)(a->u.i >= b->u.i));
414	}
415
416	free_value (a);
417	free_value (b);
418	return r;
419}
420
421struct val *
422op_le(struct val *a, struct val *b)
423{
424	struct val *r;
425
426	if (isstring (a) || isstring (b)) {
427		to_string (a);
428		to_string (b);
429		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) <= 0));
430	} else {
431		(void)to_integer(a);
432		(void)to_integer(b);
433		r = make_integer ((intmax_t)(a->u.i <= b->u.i));
434	}
435
436	free_value (a);
437	free_value (b);
438	return r;
439}
440
441struct val *
442op_ne(struct val *a, struct val *b)
443{
444	struct val *r;
445
446	if (isstring (a) || isstring (b)) {
447		to_string (a);
448		to_string (b);
449		r = make_integer ((intmax_t)(strcoll (a->u.s, b->u.s) != 0));
450	} else {
451		(void)to_integer(a);
452		(void)to_integer(b);
453		r = make_integer ((intmax_t)(a->u.i != b->u.i));
454	}
455
456	free_value (a);
457	free_value (b);
458	return r;
459}
460
461int
462chk_plus(intmax_t a, intmax_t b, intmax_t r)
463{
464
465	/* sum of two positive numbers must be positive */
466	if (a > 0 && b > 0 && r <= 0)
467		return 1;
468	/* sum of two negative numbers must be negative */
469	if (a < 0 && b < 0 && r >= 0)
470		return 1;
471	/* all other cases are OK */
472	return 0;
473}
474
475struct val *
476op_plus(struct val *a, struct val *b)
477{
478	struct val *r;
479
480	if (!to_integer(a) || !to_integer(b)) {
481		errx(ERR_EXIT, "non-numeric argument");
482	}
483
484	if (eflag) {
485		r = make_integer(a->u.i + b->u.i);
486		if (chk_plus(a->u.i, b->u.i, r->u.i)) {
487			errx(ERR_EXIT, "overflow");
488		}
489	} else
490		r = make_integer((long)a->u.i + (long)b->u.i);
491
492	free_value (a);
493	free_value (b);
494	return r;
495}
496
497int
498chk_minus(intmax_t a, intmax_t b, intmax_t r)
499{
500
501	/* special case subtraction of INTMAX_MIN */
502	if (b == INTMAX_MIN) {
503		if (a >= 0)
504			return 1;
505		else
506			return 0;
507	}
508	/* this is allowed for b != INTMAX_MIN */
509	return chk_plus (a, -b, r);
510}
511
512struct val *
513op_minus(struct val *a, struct val *b)
514{
515	struct val *r;
516
517	if (!to_integer(a) || !to_integer(b)) {
518		errx(ERR_EXIT, "non-numeric argument");
519	}
520
521	if (eflag) {
522		r = make_integer(a->u.i - b->u.i);
523		if (chk_minus(a->u.i, b->u.i, r->u.i)) {
524			errx(ERR_EXIT, "overflow");
525		}
526	} else
527		r = make_integer((long)a->u.i - (long)b->u.i);
528
529	free_value (a);
530	free_value (b);
531	return r;
532}
533
534int
535chk_times(intmax_t a, intmax_t b, intmax_t r)
536{
537	/* special case: first operand is 0, no overflow possible */
538	if (a == 0)
539		return 0;
540	/* cerify that result of division matches second operand */
541	if (r / a != b)
542		return 1;
543	return 0;
544}
545
546struct val *
547op_times(struct val *a, struct val *b)
548{
549	struct val *r;
550
551	if (!to_integer(a) || !to_integer(b)) {
552		errx(ERR_EXIT, "non-numeric argument");
553	}
554
555	if (eflag) {
556		r = make_integer(a->u.i * b->u.i);
557		if (chk_times(a->u.i, b->u.i, r->u.i)) {
558			errx(ERR_EXIT, "overflow");
559		}
560	} else
561		r = make_integer((long)a->u.i * (long)b->u.i);
562
563	free_value (a);
564	free_value (b);
565	return (r);
566}
567
568int
569chk_div(intmax_t a, intmax_t b)
570{
571	/* div by zero has been taken care of before */
572	/* only INTMAX_MIN / -1 causes overflow */
573	if (a == INTMAX_MIN && b == -1)
574		return 1;
575	/* everything else is OK */
576	return 0;
577}
578
579struct val *
580op_div(struct val *a, struct val *b)
581{
582	struct val *r;
583
584	if (!to_integer(a) || !to_integer(b)) {
585		errx(ERR_EXIT, "non-numeric argument");
586	}
587
588	if (b->u.i == 0) {
589		errx(ERR_EXIT, "division by zero");
590	}
591
592	if (eflag) {
593		r = make_integer(a->u.i / b->u.i);
594		if (chk_div(a->u.i, b->u.i)) {
595			errx(ERR_EXIT, "overflow");
596		}
597	} else
598		r = make_integer((long)a->u.i / (long)b->u.i);
599
600	free_value (a);
601	free_value (b);
602	return r;
603}
604
605struct val *
606op_rem(struct val *a, struct val *b)
607{
608	struct val *r;
609
610	if (!to_integer(a) || !to_integer(b)) {
611		errx(ERR_EXIT, "non-numeric argument");
612	}
613
614	if (b->u.i == 0) {
615		errx(ERR_EXIT, "division by zero");
616	}
617
618	if (eflag)
619		r = make_integer(a->u.i % b->u.i);
620	        /* chk_rem necessary ??? */
621	else
622		r = make_integer((long)a->u.i % (long)b->u.i);
623
624	free_value (a);
625	free_value (b);
626	return r;
627}
628
629struct val *
630op_colon(struct val *a, struct val *b)
631{
632	regex_t rp;
633	regmatch_t rm[2];
634	char errbuf[256];
635	int eval;
636	struct val *v;
637
638	/* coerce to both arguments to strings */
639	to_string(a);
640	to_string(b);
641
642	/* compile regular expression */
643	if ((eval = regcomp (&rp, b->u.s, 0)) != 0) {
644		regerror (eval, &rp, errbuf, sizeof(errbuf));
645		errx(ERR_EXIT, "%s", errbuf);
646	}
647
648	/* compare string against pattern */
649	/* remember that patterns are anchored to the beginning of the line */
650	if (regexec(&rp, a->u.s, (size_t)2, rm, 0) == 0 && rm[0].rm_so == 0) {
651		if (rm[1].rm_so >= 0) {
652			*(a->u.s + rm[1].rm_eo) = '\0';
653			v = make_str (a->u.s + rm[1].rm_so);
654
655		} else {
656			v = make_integer ((intmax_t)(rm[0].rm_eo - rm[0].rm_so));
657		}
658	} else {
659		if (rp.re_nsub == 0) {
660			v = make_integer ((intmax_t)0);
661		} else {
662			v = make_str ("");
663		}
664	}
665
666	/* free arguments and pattern buffer */
667	free_value (a);
668	free_value (b);
669	regfree (&rp);
670
671	return v;
672}
673