sbase/expr.c

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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 void
tonum(struct val *v)
{
const char *errstr;
long long d;
/* check if val is the result of an earlier calculation */
if (!v->str)
return;
d = strtonum(v->str, LLONG_MIN, LLONG_MAX, &errstr);
if (errstr)
enprintf(2, "error: expected integer, got %s\n", v->str);
v->num = d;
}
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;
const char *err1, *err2;
long long d1, d2;
d1 = strtonum(a->str, LLONG_MIN, LLONG_MAX, &err1);
d2 = strtonum(b->str, LLONG_MIN, LLONG_MAX, &err2);
if (!err1 && !err2) {
ret = (d1 > d2) - (d1 < d2);
} 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];
size_t anchlen;
char *s, *p, *anchreg;
char *str = vstr->str, *regx = vregx->str;
/* anchored regex */
anchlen = strlen(regx) + 1 + 1;
anchreg = emalloc(anchlen);
estrlcpy(anchreg, "^", anchlen);
estrlcat(anchreg, regx, anchlen);
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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';
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 '+': tonum(a); tonum(b); ret.num = a->num + b->num; break;
case '-': tonum(a); tonum(b); ret.num = a->num - b->num; break;
case '*': tonum(a); tonum(b); ret.num = a->num * b->num; break;
case '/': tonum(a); tonum(b); ezero(b); ret.num = a->num / b->num; break;
case '%': tonum(a); tonum(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)
{
int type = VAL;
char *ops = "|&=><+-*/%():";
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;
}
return type;
}
static int
parse(char *expr[], int numexpr)
{
struct val *valhead, *valp, v = { .str = NULL, .num = 0 };
int *ophead, *opp, 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,
};
valp = valhead = enreallocarray(3, NULL, numexpr, sizeof(*valp));
opp = ophead = enreallocarray(3, NULL, numexpr, sizeof(*opp));
for (; *expr; expr++) {
switch ((type = lex(*expr, &v))) {
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case VAL:
/* treatment of *expr is not known until
* doop(); treat as a string for now */
valp->str = *expr;
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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}
int
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main(int argc, char *argv[])
{
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int ret;
argv0 = *argv, argv0 ? (argc--, argv++) : (void *)0;
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ret = !parse(argv, argc);
if (fshut(stdout, "<stdout>"))
ret = 3;
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return ret;
}