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Refactor expr.c

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FRIGN 2014-11-16 20:29:29 +01:00 committed by sin
parent f6552e3669
commit abdd0671f7
1 changed files with 58 additions and 46 deletions
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102
expr.c
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@ -23,17 +23,16 @@ static Val match(Val, Val);
static void num(Val); static void num(Val);
static int valcmp(Val, Val); static int valcmp(Val, Val);
static char *valstr(Val, char*, size_t); static char *valstr(Val, char*, size_t);
static int yylex(void); static int lex(char *);
static int yyparse(int); static int parse(char **, int);
static char **args;
static size_t intlen; static size_t intlen;
static Val yylval; static Val lastval;
static void static void
ezero(intmax_t n) ezero(intmax_t n)
{ {
if(n == 0) if (n == 0)
enprintf(2, "division by zero\n"); enprintf(2, "division by zero\n");
} }
@ -159,17 +158,14 @@ valstr(Val val, char *buf, size_t bufsiz)
} }
static int static int
yylex(void) lex(char *p)
{ {
intmax_t d; intmax_t d;
char *q, *p, *ops = "|&=><+-*/%():"; char *q, *ops = "|&=><+-*/%():";
if (!(p = *args++))
return 0;
d = strtoimax(p, &q, 10); d = strtoimax(p, &q, 10);
if (*p && !*q) { if (*p && !*q) {
yylval = (Val){ NULL, d }; lastval = (Val){ NULL, d };
return VAL; return VAL;
} }
@ -183,17 +179,18 @@ yylex(void)
if (strcmp(p, "!=") == 0) if (strcmp(p, "!=") == 0)
return NE; return NE;
yylval = (Val){ p, 0 }; lastval = (Val){ p, 0 };
return VAL; return VAL;
} }
static int static int
yyparse(int argc) parse(char **expr, int exprlen)
{ {
Val vals[argc], *vtop = vals; Val val[exprlen], *valp = val;
int ops [argc], *otop = ops; int op[exprlen], *opp = op;
int type, last = 0; int i, type, lasttype = 0;
char prec[] = { char prec[] = {
[ 0 ] = 0, [VAL] = 0,
['|'] = 1, ['|'] = 1,
['&'] = 2, ['&'] = 2,
['='] = 3, ['>'] = 3, [GE] = 3, ['<'] = 3, [LE] = 3, [NE] = 3, ['='] = 3, ['>'] = 3, [GE] = 3, ['<'] = 3, [LE] = 3, [NE] = 3,
@ -202,55 +199,70 @@ yyparse(int argc)
[':'] = 6, [':'] = 6,
}; };
while((type = yylex())) { for (i = 0; i < exprlen; i++) {
type = lex(expr[i]);
switch (type) { switch (type) {
case VAL: *vtop++ = yylval; break; case VAL:
case '(': *otop++ = '(' ; break; *valp++ = lastval;
break;
case '(':
*opp++ = '(';
break;
case ')': case ')':
if (last == '(') if (lasttype == '(')
enprintf(2, "syntax error: empty ( )\n"); enprintf(2, "syntax error: empty ( )\n");
while(otop > ops && otop[-1] != '(') while (opp > op && opp[-1] != '(')
doop(ops, &otop, vals, &vtop); doop(op, &opp, val, &valp);
if (otop == ops) if (opp == op)
enprintf(2, "syntax error: extra )\n"); enprintf(2, "syntax error: extra )\n");
otop--; opp--;
break; break;
default : default :
if (prec[last]) if (prec[lasttype])
enprintf(2, "syntax error: extra operator\n"); enprintf(2, "syntax error: extra operator\n");
while (otop > ops && prec[otop[-1]] >= prec[type]) while (opp > op && prec[opp[-1]] >= prec[type])
doop(ops, &otop, vals, &vtop); doop(op, &opp, val, &valp);
*otop++ = type; *opp++ = type;
break; break;
} }
last = type; lasttype = type;
} }
while(otop > ops) while (opp > op)
doop(ops, &otop, vals, &vtop); doop(op, &opp, val, &valp);
if (vtop == vals) if (valp == val)
enprintf(2, "syntax error: missing expression\n"); enprintf(2, "syntax error: missing expression\n");
if (vtop - vals > 1) if (valp - val > 1)
enprintf(2, "syntax error: extra expression\n"); enprintf(2, "syntax error: extra expression\n");
vtop--; valp--;
if (vtop->s) if (valp->s)
printf("%s\n", vtop->s); printf("%s\n", valp->s);
else 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 int
main(int argc, char **argv) main(int argc, char *argv[])
{ {
if (!(intlen = snprintf(NULL, 0, "%"PRIdMAX, INTMAX_MIN) + 1)) intmax_t n = INTMAX_MIN;
enprintf(3, "failed to get max digits\n");
args = argv + 1; /* Get the maximum number of digits (+ sign) */
if (*args && !strcmp("--", *args)) for (intlen = (n < 0); n; n /= 10, ++intlen);
++args;
return !yyparse(argc); ARGBEGIN {
default:
usage();
} ARGEND;
return !parse(argv, argc);
} }