now comparisons

1 files changed, 53 insertions, 0 deletions

diff --git a/expr.y b/expr.y
index 785b004..b2f2061 100644
--- a/expr.y
+++ b/expr.y
@@ -1,12 +1,48 @@
 %{
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "expr.h"
+#include "y.tab.h"
 
 extern int yylex(void);
 extern int yyerror(const char *s);
 
 static void breakpoint(void) { }
+
+static void expr_only_integers(YYSTYPE *y1, YYSTYPE *y2)
+{
+	if (y1->type == STRING) {
+		fprintf(stderr, "expr: %s is not an integer\n", y1->u.s);
+		exit(1);
+	}
+	if (y2->type == STRING) {
+		fprintf(stderr, "expr: %s is not an integer\n", y2->u.s);
+		exit(1);
+	}
+}
+
+static int expr_compare(YYSTYPE *y1, YYSTYPE *y2)
+{
+	if (y1->type == INTEGER && y2->type == INTEGER) {
+		return y1->u.i - y2->u.i;
+	}
+
+	char buf[64];
+	char *s1 = y1->u.s;
+	char *s2 = y2->u.s;
+
+	if (y1->type == INTEGER) {
+		snprintf(buf, sizeof(buf), "%d", y1->u.i);
+		s1 = buf;
+	} else if (y2->type == INTEGER) {
+		snprintf(buf, sizeof(buf), "%d", y2->u.i);
+		s2 = buf;
+	}
+
+	return strcmp(s1, s2);
+}
 %}
 
 %token INTEGER
@@ -37,46 +73,63 @@ expr	: STRING {
 	}
 
 	| expr '*' expr {
+		expr_only_integers(&$1, &$3);
 		$$.u.i = $1.u.i * $3.u.i;
 		printf("%d\n", $$.u.i);
 	}
 
 	| expr '/' expr {
+		expr_only_integers(&$1, &$3);
 		$$.u.i = $1.u.i / $3.u.i;
 		printf("%d\n", $$.u.i);
 	}
 
 	| expr '%' expr {
+		expr_only_integers(&$1, &$3);
 		$$.u.i = $1.u.i % $3.u.i;
 		printf("%d\n", $$.u.i);
 	}
 
 	| expr '+' expr {
+		expr_only_integers(&$1, &$3);
 		$$.u.i = $1.u.i + $3.u.i;
 		printf("%d\n", $$.u.i);
 	}
 
 	| expr '-' expr {
+		expr_only_integers(&$1, &$3);
 		$$.u.i = $1.u.i - $3.u.i;
 		printf("%d\n", $$.u.i);
 	}
 
 	| expr '=' expr {
+		int r = expr_compare(&$1, &$3) == 0;
+		printf("%d\n", r);
 	}
 
 	| expr NE expr {
+		int r = expr_compare(&$1, &$3) != 0;
+		printf("%d\n", r);
 	}
 
 	| expr '<' expr {
+		int r = expr_compare(&$1, &$3) < 0;
+		printf("%d\n", r);
 	}
 
 	| expr LE expr {
+		int r = expr_compare(&$1, &$3) <= 0;
+		printf("%d\n", r);
 	}
 
 	| expr '>' expr {
+		int r = expr_compare(&$1, &$3) > 0;
+		printf("%d\n", r);
 	}
 
 	| expr GE expr {
+		int r = expr_compare(&$1, &$3) >= 0;
+		printf("%d\n", r);
 	}
 
 	| expr '&' expr {