sbase/expr.c

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5.9 KiB
C
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/* See LICENSE file for copyright and license details. */
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
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#include "utf.h"
#include "util.h"
/* tokens, one-character operators represent themselves */
enum {
VAL = CHAR_MAX + 1, GE, LE, NE
};
struct val {
char *str;
long long num;
};
static size_t maxdigits;
static void
enan(struct val *v)
{
if (!v->str)
return;
enprintf(2, "syntax error: expected integer, got %s\n", v->str);
}
static void
ezero(struct val *v)
{
if (v->num != 0)
return;
enprintf(2, "division by zero\n");
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}
static int
valcmp(struct val *a, struct val *b)
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{
int ret;
char buf[maxdigits];
if (!a->str && !b->str) {
ret = (a->num > b->num) - (a->num < b->num);
} else if (a->str && !b->str) {
snprintf(buf, sizeof(buf), "%lld", b->num);
ret = strcmp(a->str, buf);
} else if (!a->str && b->str) {
snprintf(buf, sizeof(buf), "%lld", a->num);
ret = strcmp(buf, b->str);
} else {
ret = strcmp(a->str, b->str);
}
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return ret;
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}
static void
match(struct val *vstr, struct val *vregx, struct val *ret)
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{
regex_t re;
regmatch_t matches[2];
long long d;
char strbuf[maxdigits + 1], regxbuf[maxdigits + 1],
*s, *p, *anchreg, *str, *regx;
const char *errstr;
if (!vstr->str) {
snprintf(strbuf, sizeof(strbuf), "%lld", vstr->num);
str = strbuf;
} else {
str = vstr->str;
}
if (!vregx->str) {
snprintf(regxbuf, sizeof(regxbuf), "%lld", vregx->num);
regx = regxbuf;
} else {
regx = vregx->str;
}
/* anchored regex */
anchreg = emalloc(strlen(regx) + 2);
estrlcpy(anchreg, "^", sizeof(anchreg));
estrlcat(anchreg, regx, sizeof(anchreg));
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enregcomp(3, &re, anchreg, 0);
free(anchreg);
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if (regexec(&re, str, 2, matches, 0)) {
regfree(&re);
ret->str = re.re_nsub ? "" : NULL;
return;
} else if (re.re_nsub) {
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regfree(&re);
s = str + matches[1].rm_so;
p = str + matches[1].rm_eo;
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*p = '\0';
d = strtonum(s, LLONG_MIN, LLONG_MAX, &errstr);
if (!errstr) {
ret->num = d;
return;
} else {
ret->str = enstrdup(3, s);
return;
}
} else {
regfree(&re);
str += matches[0].rm_so;
ret->num = utfnlen(str, matches[0].rm_eo - matches[0].rm_so);
return;
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}
}
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static void
doop(int *ophead, int *opp, struct val *valhead, struct val *valp)
{
struct val ret = { .str = NULL, .num = 0 }, *a, *b;
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int op;
/* an operation "a op b" needs an operator and two values */
if (opp[-1] == '(')
enprintf(2, "syntax error: extra (\n");
if (valp - valhead < 2)
enprintf(2, "syntax error: missing expression or extra operator\n");
a = valp - 2;
b = valp - 1;
op = opp[-1];
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switch (op) {
case '|':
if ( a->str && *a->str) ret.str = a->str;
else if (!a->str && a->num) ret.num = a->num;
else if ( b->str && *b->str) ret.str = b->str;
else ret.num = b->num;
break;
case '&':
if (((a->str && *a->str) || a->num) &&
((b->str && *b->str) || b->num)) {
ret.str = a->str;
ret.num = a->num;
}
break;
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case '=': ret.num = (valcmp(a, b) == 0); break;
case '>': ret.num = (valcmp(a, b) > 0); break;
case GE : ret.num = (valcmp(a, b) >= 0); break;
case '<': ret.num = (valcmp(a, b) < 0); break;
case LE : ret.num = (valcmp(a, b) <= 0); break;
case NE : ret.num = (valcmp(a, b) != 0); break;
case '+': enan(a); enan(b); ret.num = a->num + b->num; break;
case '-': enan(a); enan(b); ret.num = a->num - b->num; break;
case '*': enan(a); enan(b); ret.num = a->num * b->num; break;
case '/': enan(a); enan(b); ezero(b); ret.num = a->num / b->num; break;
case '%': enan(a); enan(b); ezero(b); ret.num = a->num % b->num; break;
case ':': match(a, b, &ret); break;
}
valp[-2] = ret;
}
static int
lex(char *s, struct val *v)
{
long long d;
int type = VAL;
char *ops = "|&=><+-*/%():";
const char *errstr;
d = strtonum(s, LLONG_MIN, LLONG_MAX, &errstr);
if (!errstr) {
/* integer */
v->num = d;
} else if (s[0] && strchr(ops, s[0]) && !s[1]) {
/* one-char operand */
type = s[0];
} else if (s[0] && strchr("><!", s[0]) && s[1] == '=' && !s[2]) {
/* two-char operand */
type = (s[0] == '>') ? GE : (s[0] == '<') ? LE : NE;
} else {
/* string */
v->str = s;
}
return type;
}
static int
parse(char *expr[], int numexpr)
{
struct val valhead[numexpr], *valp = valhead, v = { .str = NULL, .num = 0 };
int ophead[numexpr], *opp = ophead, type, lasttype = 0;
char prec[] = {
[ 0 ] = 0, [VAL] = 0, ['('] = 0, [')'] = 0,
['|'] = 1,
['&'] = 2,
['='] = 3, ['>'] = 3, [GE] = 3, ['<'] = 3, [LE] = 3, [NE] = 3,
['+'] = 4, ['-'] = 4,
['*'] = 5, ['/'] = 5, ['%'] = 5,
[':'] = 6,
};
for (; *expr; expr++) {
switch ((type = lex(*expr, &v))) {
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case VAL:
(*valp).str = v.str;
(*valp).num = v.num;
valp++;
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break;
case '(':
*opp++ = type;
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break;
case ')':
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if (lasttype == '(')
enprintf(2, "syntax error: empty ( )\n");
while (opp > ophead && opp[-1] != '(')
doop(ophead, opp--, valhead, valp--);
if (opp == ophead)
enprintf(2, "syntax error: extra )\n");
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opp--;
break;
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default: /* operator */
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if (prec[lasttype])
enprintf(2, "syntax error: extra operator\n");
while (opp > ophead && prec[opp[-1]] >= prec[type])
doop(ophead, opp--, valhead, valp--);
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*opp++ = type;
break;
}
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lasttype = type;
v.str = NULL;
v.num = 0;
}
while (opp > ophead)
doop(ophead, opp--, valhead, valp--);
if (valp == valhead)
enprintf(2, "syntax error: missing expression\n");
if (--valp > valhead)
enprintf(2, "syntax error: extra expression\n");
if (valp->str)
puts(valp->str);
else
printf("%lld\n", valp->num);
return (valp->str && *valp->str) || valp->num;
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}
static void
usage(void)
{
enprintf(3, "usage: %s expression\n", argv0);
}
int
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main(int argc, char *argv[])
{
long long n = LLONG_MIN;
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/* maximum number of digits + sign */
for (maxdigits = (n < 0); n; n /= 10, ++maxdigits);
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ARGBEGIN {
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default:
usage();
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} ARGEND;
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return !parse(argv, argc);
}