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Refactor expr.c

This commit is contained in:
FRIGN 2014-11-16 20:29:29 +01:00 committed by sin
parent f6552e3669
commit abdd0671f7

104
expr.c
View File

@ -23,17 +23,16 @@ static Val match(Val, Val);
static void num(Val);
static int valcmp(Val, Val);
static char *valstr(Val, char*, size_t);
static int yylex(void);
static int yyparse(int);
static int lex(char *);
static int parse(char **, int);
static char **args;
static size_t intlen;
static Val yylval;
static Val lastval;
static void
ezero(intmax_t n)
{
if(n == 0)
if (n == 0)
enprintf(2, "division by zero\n");
}
@ -61,7 +60,7 @@ doop(int *ops, int **otop, Val *vals, Val **vtop)
case '|':
if (a.s && *a.s)
ret = (Val){ a.s, 0 };
else if (!a.s && a.n)
else if (!a.s && a.n)
ret = (Val){ NULL, a.n };
else if (b.s && *b.s)
ret = (Val){ b.s, 0 };
@ -159,17 +158,14 @@ valstr(Val val, char *buf, size_t bufsiz)
}
static int
yylex(void)
lex(char *p)
{
intmax_t d;
char *q, *p, *ops = "|&=><+-*/%():";
if (!(p = *args++))
return 0;
char *q, *ops = "|&=><+-*/%():";
d = strtoimax(p, &q, 10);
if (*p && !*q) {
yylval = (Val){ NULL, d };
lastval = (Val){ NULL, d };
return VAL;
}
@ -183,17 +179,18 @@ yylex(void)
if (strcmp(p, "!=") == 0)
return NE;
yylval = (Val){ p, 0 };
lastval = (Val){ p, 0 };
return VAL;
}
static int
yyparse(int argc)
parse(char **expr, int exprlen)
{
Val vals[argc], *vtop = vals;
int ops [argc], *otop = ops;
int type, last = 0;
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,
@ -202,55 +199,70 @@ yyparse(int argc)
[':'] = 6,
};
while((type = yylex())) {
for (i = 0; i < exprlen; i++) {
type = lex(expr[i]);
switch (type) {
case VAL: *vtop++ = yylval; break;
case '(': *otop++ = '(' ; break;
case VAL:
*valp++ = lastval;
break;
case '(':
*opp++ = '(';
break;
case ')':
if (last == '(')
if (lasttype == '(')
enprintf(2, "syntax error: empty ( )\n");
while(otop > ops && otop[-1] != '(')
doop(ops, &otop, vals, &vtop);
if (otop == ops)
while (opp > op && opp[-1] != '(')
doop(op, &opp, val, &valp);
if (opp == op)
enprintf(2, "syntax error: extra )\n");
otop--;
opp--;
break;
default :
if (prec[last])
if (prec[lasttype])
enprintf(2, "syntax error: extra operator\n");
while (otop > ops && prec[otop[-1]] >= prec[type])
doop(ops, &otop, vals, &vtop);
*otop++ = type;
while (opp > op && prec[opp[-1]] >= prec[type])
doop(op, &opp, val, &valp);
*opp++ = type;
break;
}
last = type;
lasttype = type;
}
while(otop > ops)
doop(ops, &otop, vals, &vtop);
while (opp > op)
doop(op, &opp, val, &valp);
if (vtop == vals)
if (valp == val)
enprintf(2, "syntax error: missing expression\n");
if (vtop - vals > 1)
if (valp - val > 1)
enprintf(2, "syntax error: extra expression\n");
vtop--;
if (vtop->s)
printf("%s\n", vtop->s);
valp--;
if (valp->s)
printf("%s\n", valp->s);
else
printf("%"PRIdMAX"\n", vtop->n);
printf("%"PRIdMAX"\n", valp->n);
return (vtop->s && *vtop->s) || vtop->n;
return (valp->s && *valp->s) || valp->n;
}
static void
usage(void)
{
eprintf("usage: %s EXPRESSION\n", argv0);
}
int
main(int argc, char **argv)
main(int argc, char *argv[])
{
if (!(intlen = snprintf(NULL, 0, "%"PRIdMAX, INTMAX_MIN) + 1))
enprintf(3, "failed to get max digits\n");
intmax_t n = INTMAX_MIN;
args = argv + 1;
if (*args && !strcmp("--", *args))
++args;
/* Get the maximum number of digits (+ sign) */
for (intlen = (n < 0); n; n /= 10, ++intlen);
return !yyparse(argc);
ARGBEGIN {
default:
usage();
} ARGEND;
return !parse(argv, argc);
}