sbase/expr.c
FRIGN b98bf41ecc Add mandoc-manpage for expr(1)
and mark it as finished in README.
Upon further checking, expr(1) turns out to be implicitly UTF-8 compliant.
2015-01-25 16:49:46 +01:00

288 lines
5.6 KiB
C

/* See LICENSE file for copyright and license details. */
#include <inttypes.h>
#include <limits.h>
#include <regex.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "util.h"
enum {
VAL = CHAR_MAX + 1, GE, LE, NE
};
typedef struct {
char *s;
intmax_t n;
} Val;
static void enan(Val);
static void ezero(intmax_t);
static void doop(int*, int**, Val*, Val**);
static Val match(Val, Val);
static int valcmp(Val, Val);
static char *valstr(Val, char *, size_t);
static int lex(char *);
static int parse(char **, int);
static size_t intlen;
static Val lastval;
static void
enan(Val v)
{
if (v.s)
enprintf(2, "syntax error: expected integer got `%s'\n", v.s);
}
static void
ezero(intmax_t n)
{
if (n == 0)
enprintf(2, "division by zero\n");
}
static void
doop(int *op, int **opp, Val *val, Val **valp)
{
Val ret, a, b;
int o;
/* For an operation, we need a valid operator
* and two values on the stack */
if ((*opp)[-1] == '(')
enprintf(2, "syntax error: extra (\n");
if (*valp - val < 2)
enprintf(2, "syntax error: missing expression or extra operator\n");
a = (*valp)[-2];
b = (*valp)[-1];
o = (*opp)[-1];
switch (o) {
case '|':
if (a.s && *a.s) {
ret = (Val){ a.s, 0 };
} else if (!a.s && a.n) {
ret = (Val){ NULL, a.n };
} else if (b.s && *b.s) {
ret = (Val){ b.s, 0 };
} else {
ret = (Val){ NULL, b.n };
}
break;
case '&':
if (((a.s && *a.s) || a.n) &&
((b.s && *b.s) || b.n)) {
ret = a;
} else {
ret = (Val){ NULL, 0 };
}
break;
case '=': ret = (Val){ NULL, valcmp(a, b) == 0 }; break;
case '>': ret = (Val){ NULL, valcmp(a, b) > 0 }; break;
case GE : ret = (Val){ NULL, valcmp(a, b) >= 0 }; break;
case '<': ret = (Val){ NULL, valcmp(a, b) < 0 }; break;
case LE : ret = (Val){ NULL, valcmp(a, b) <= 0 }; break;
case NE : ret = (Val){ NULL, valcmp(a, b) != 0 }; break;
case '+': enan(a); enan(b); ret = (Val){ NULL, a.n + b.n }; break;
case '-': enan(a); enan(b); ret = (Val){ NULL, a.n - b.n }; break;
case '*': enan(a); enan(b); ret = (Val){ NULL, a.n * b.n }; break;
case '/': enan(a); enan(b); ezero(b.n); ret = (Val){ NULL, a.n / b.n }; break;
case '%': enan(a); enan(b); ezero(b.n); ret = (Val){ NULL, a.n % b.n }; break;
case ':': ret = match(a, b); break;
}
(*valp)[-2] = ret;
(*opp)--;
(*valp)--;
}
static Val
match(Val vstr, Val vregx)
{
intmax_t d;
char *anchreg, *ret, *p;
char buf1[intlen], buf2[intlen], *str, *regx;
regoff_t len;
regex_t re;
regmatch_t matches[2];
str = valstr(vstr, buf1, sizeof(buf1));
regx = valstr(vregx, buf2, sizeof(buf2));
anchreg = malloc(strlen(regx) + 2);
if (!anchreg)
enprintf(3, "malloc:");
snprintf(anchreg, strlen(regx) + 2, "^%s", regx);
enregcomp(3, &re, anchreg, 0);
free(anchreg);
if (regexec(&re, str, 2, matches, 0)) {
regfree(&re);
return (Val){ (re.re_nsub ? "" : NULL), 0 };
}
if (re.re_nsub) {
regfree(&re);
len = matches[1].rm_eo - matches[1].rm_so + 1;
ret = malloc(len);
if (!ret)
enprintf(3, "malloc:");
strlcpy(ret, str + matches[1].rm_so, len);
d = strtoimax(ret, &p, 10);
if (*ret && !*p) {
free(ret);
return (Val){ NULL, d };
}
return (Val){ ret, 0 };
}
regfree(&re);
return (Val){ NULL, matches[0].rm_eo - matches[0].rm_so };
}
static int
valcmp(Val a, Val b)
{
char buf1[intlen], buf2[intlen], *astr, *bstr;
astr = valstr(a, buf1, sizeof(buf1));
bstr = valstr(b, buf2, sizeof(buf2));
return strcmp(astr, bstr);
}
static char *
valstr(Val val, char *buf, size_t bufsiz)
{
if (val.s)
return val.s;
snprintf(buf, bufsiz, "%"PRIdMAX, val.n);
return buf;
}
static int
lex(char *p)
{
intmax_t d;
char *q, *ops = "|&=><+-*/%():";
/* clean integer */
d = strtoimax(p, &q, 10);
if (*p && !*q) {
lastval = (Val){ NULL, d };
return VAL;
}
/* one-char operand */
if (*p && !*(p + 1) && strchr(ops, *p))
return *p;
/* two-char operand */
if (*p && *(p + 1) == '=' && !*(p + 2)) {
switch (*p) {
case '>':
return GE;
case '<':
return LE;
case '!':
return NE;
}
}
/* nothing matched, treat as string */
lastval = (Val){ p, 0 };
return VAL;
}
static int
parse(char **expr, int exprlen)
{
Val val[exprlen], *valp = val;
int op[exprlen], *opp = op;
int i, type, lasttype = 0;
char prec[] = {
[ 0 ] = 0, [VAL] = 0,
['|'] = 1,
['&'] = 2,
['='] = 3, ['>'] = 3, [GE] = 3, ['<'] = 3, [LE] = 3, [NE] = 3,
['+'] = 4, ['-'] = 4,
['*'] = 5, ['/'] = 5, ['%'] = 5,
[':'] = 6,
};
for (i = 0; i < exprlen; i++) {
type = lex(expr[i]);
switch (type) {
case VAL:
*valp++ = lastval;
break;
case '(':
*opp++ = '(';
break;
case ')':
if (lasttype == '(')
enprintf(2, "syntax error: empty ( )\n");
while (opp > op && opp[-1] != '(')
doop(op, &opp, val, &valp);
if (opp == op)
enprintf(2, "syntax error: extra )\n");
opp--;
break;
default :
if (prec[lasttype])
enprintf(2, "syntax error: extra operator\n");
while (opp > op && prec[opp[-1]] >= prec[type])
doop(op, &opp, val, &valp);
*opp++ = type;
break;
}
lasttype = type;
}
while (opp > op)
doop(op, &opp, val, &valp);
if (valp == val)
enprintf(2, "syntax error: missing expression\n");
if (valp - val > 1)
enprintf(2, "syntax error: extra expression\n");
valp--;
if (valp->s)
printf("%s\n", valp->s);
else
printf("%"PRIdMAX"\n", valp->n);
return (valp->s && *valp->s) || valp->n;
}
static void
usage(void)
{
eprintf("usage: %s EXPRESSION\n", argv0);
}
int
main(int argc, char *argv[])
{
intmax_t n = INTMAX_MIN;
/* Get the maximum number of digits (+ sign) */
for (intlen = (n < 0); n; n /= 10, ++intlen);
ARGBEGIN {
default:
usage();
} ARGEND;
return !parse(argv, argc);
}