From: short <>
Date: Mon, 9 Jul 2001 23:04:21 +0000 (+0000)
Subject: Improved version, originally named "ev2.c"
X-Git-Tag: rh71~79
X-Git-Url: http://git.jankratochvil.net/?p=nethome.git;a=commitdiff_plain;h=620a419f5f5e2e8f5fe9888ba375006bc838083e

Improved version, originally named "ev2.c"
---

diff --git a/src/ev.c b/src/ev.c
index f8f8d95..0ce6142 100644
--- a/src/ev.c
+++ b/src/ev.c
@@ -3,7 +3,11 @@
 #include <ctype.h>
 #include <assert.h>
 
-#define BUFSIZE 100
+#define NDEBUG
+
+#define BUFSIZE 1024
+
+#define bail(arg...) do { fprintf(stderr, ##arg); exit(EXIT_FAILURE); } while (0)
 
 char *arg;
 
@@ -11,6 +15,23 @@ int istack[BUFSIZE];
 char opstack[BUFSIZE];
 int istackp,opstackp;
 
+#ifdef NDEBUG
+#define dump(x)
+#else
+static void dump(char *pref)
+{
+int i;
+	fprintf(stderr,"%s: i[",pref);
+	for (i=0;i<istackp;i++) {
+		if (i) fputc(',',stderr);
+		fprintf(stderr,"%d",istack[i]);
+		}
+	fprintf(stderr,"],op=[");
+	for (i=0;i<opstackp;i++) fputc(opstack[i],stderr);
+	fprintf(stderr,"]\n");
+}
+#endif
+
 static char lex(int *ip)
 {
 char c;
@@ -27,8 +48,7 @@ long l;
 			*ip=l;
 			return 'n';
 		default:
-			fprintf(stderr,"Invalid characted in string: %s\n",arg);
-			exit(EXIT_FAILURE);
+			bail("Invalid characted in string: %s\n",arg);
 		}
 }
 
@@ -46,21 +66,18 @@ static int oppri(char op)
 
 static void evalit(void)
 {
-	assert(opstackp);
-	if (istackp<2) {
-		fprintf(stderr,"2 arguments for operator required!\n");
-		exit(EXIT_FAILURE);
-		}
+	dump("evalit()");
+	assert(opstackp); opstackp--;
+	if (istackp<2) 
+		if (opstack[opstackp]!='(') bail("2 arguments for operator '%c' required!\n",opstack[opstackp]);
+		else bail("Stray '('!\n");
 	istackp--;
-	switch (opstack[--opstackp]) {
+	switch (opstack[opstackp]) {
 		case '+': istack[istackp-1]+=istack[istackp]; break;
 		case '-': istack[istackp-1]-=istack[istackp]; break;
 		case '*': istack[istackp-1]*=istack[istackp]; break;
 		case '/': 
-			if (!istack[istackp]) {
-				fprintf(stderr,"Division of %d by zero not supported!\n",istack[istackp-1]);
-				exit(EXIT_FAILURE);
-				}
+			if (!istack[istackp]) bail("Division of %d by zero not supported!\n",istack[istackp-1]);
 			istack[istackp-1]/=istack[istackp];
 			break;
 		}
@@ -73,46 +90,36 @@ int mypri=oppri(op);
 		evalit();
 	if (!op) return;
 	if (op==')') {
-		if (!opstackp || opstack[opstackp-1]!='(') {
-			fprintf(stderr,"Not enough content for brackets-inside space!\n");
-			exit(EXIT_FAILURE);
-			}
+		if (!opstackp || opstack[opstackp-1]!='(')
+			bail("Not enough content for brackets-inside space!\n");
 		opstackp--;
 		return;
 		}
-	assert(opstackp<BUFSIZE);
+	if (opstackp>=BUFSIZE) bail("Too many operators (%d is max)!\n",BUFSIZE);
 	opstack[opstackp++]=op;
 }
 
 static void process(void)
 {
-char lastop=0,op;
+char lastop,op;
 int curi;
 
 	istackp=opstackp=0;
-	for (;;) switch ((op=lex(&curi))) {
+	for (lastop=0;;lastop=op) switch (op=lex(&curi)) {
 		case 'n':
-			if (lastop=='n') {
-				fprintf(stderr,"Two successive numbers not permitted!\n");
-				exit(EXIT_FAILURE);
-				}
-			assert(istackp<BUFSIZE);
+			if (lastop=='n') bail("Two successive numbers not permitted!\n");
+			if (istackp>=BUFSIZE) bail("Too many operators (%d is max)!\n",BUFSIZE);
 			istack[istackp++]=curi;
 			break;
 		case '(':
-			if (lastop=='n') {
-				fprintf(stderr,"Open-bracket not permitted after number!\n");
-				exit(EXIT_FAILURE);
-				}
+			if (lastop=='n') bail("Open-bracket not permitted after number!\n");
 			pushop(op);
 			break;
 		case '+': case '-': case '*': case '/': case ')': pushop(op); break;
 		case 0:
 			pushop(op);
-			if (istackp!=1||opstackp) {
-				fprintf(stderr,"Machine not in sane state on the end of expression, ints=%d,ops=%d!\n",istackp,opstackp);
-				exit(EXIT_FAILURE);
-				}
+			if (istackp!=1||opstackp)
+				bail("Machine not in sane state on the end of expression, ints=%d,ops=%d!\n",istackp,opstackp);
 			printf("%d\n",istack[0]);
 			return;
 		default: assert(0);