[hackers] [sbase] Refactor expr.c || FRIGN

From: <git_AT_suckless.org>
Date: Mon, 17 Nov 2014 11:05:23 +0100

commit abdd0671f7d69dd4d48e2c692eb26bc658161763
Author: FRIGN <dev_AT_frign.de>
Date: Sun Nov 16 20:29:29 2014 +0100

    Refactor expr.c

diff --git a/expr.c b/expr.c
index 3e0cd8e..e11479e 100644
--- a/expr.c
+++ b/expr.c
_AT_@ -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");
 }
 
_AT_@ -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 };
_AT_@ -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;
         }
 
_AT_@ -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,
_AT_@ -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;
+
+ /* Get the maximum number of digits (+ sign) */
+ for (intlen = (n < 0); n; n /= 10, ++intlen);
 
- args = argv + 1;
- if (*args && !strcmp("--", *args))
- ++args;
+ ARGBEGIN {
+ default:
+ usage();
+ } ARGEND;
 
- return !yyparse(argc);
+ return !parse(argv, argc);
 }
Received on Mon Nov 17 2014 - 11:05:23 CET