Merge pull request #1 from mtardy/single-char-variables

Single char variables

.gitignore

@@ -1,3 +1,6 @@
+# vscode settings
+.vscode/
+
 # ignore generated parser
 calc.c
 

calc.leg

@@ -8,12 +8,17 @@
 
 #define YYSTYPE int
 YYSTYPE yylval = 0;
+int var[26];
 
 %}
 
 start	=	e:exp					{ yylval = e }
 
-exp		=	- s:sum					{ $$ = s }
+exp		=	- (a:assign				{ $$ = a }
+			| s:sum 				{ $$ = s }
+			)
+
+assign	=	l:LETTER EQUAL n:sum	{ $$ = var[l - 'a'] = n }
 
 sum		=	PLUS* l:prod
 			( PLUS+ r:prod			{ l += r }
@@ -23,11 +28,14 @@ sum		=	PLUS* l:prod
 prod	=	l:neg
 			( MULTI		r:neg		{ l *= r }
 			| DIVIDE	r:neg		{ l /= r }
-            | MODULO    r:neg       { l %= r }
+			| MODULO	r:neg		{ l %= r }
 			)*						{ $$ = l }
 
 neg		=	MINUS n:neg				{ $$ = -n }
-			| n:NUMBER				{ $$ = n }
+			| n:value				{ $$ = n }
+
+value	=	n:NUMBER				{ $$ = n }
+			| l:LETTER				{ $$ = var[l - 'a'] }
 
 -		=	[ \t]*
 NUMBER	=	< [0-9]+ >	-			{ $$ = atoi(yytext) }
@@ -35,7 +43,11 @@ PLUS	=	'+'			-
 MINUS	=	'-'			-
 MULTI	=	'*'			-
 DIVIDE	=	'/'			-
-MODULO  =   '%'         -
+MODULO	=	'%'			-
+LETTER	=	(< [a-z] >				{ $$ = yytext[0] }
+			|< [A-Z] >				{ $$ = yytext[0] + 'a' - 'A' }
+			)			-
+EQUAL	=	'='			-
 
 %%
 
@@ -44,6 +56,11 @@ int main(int argc, char **argv)
 	while (yyparse()) {
 		printf("%d\n", yylval);
 	}
+	/*
+	for (int i = 0; i < 26; i++) {
+		printf("var[%d]=%d ", i, var[i]);
+	}
+	*/
 
 	return 0;
 }

test.sh

@@ -15,5 +15,8 @@ echo "5%2" | ./${PROG} | cmp <(echo "1") && echo "test#9 passed!" || true
 echo "3*2+10*2" | ./${PROG} | cmp <(echo "26") && echo "test#10 passed!" || true
 echo "-3*2+10*2" | ./${PROG} | cmp <(echo "14") && echo "test#11 passed!" || true
 echo "- 5%  2 +2-6 / 2" | ./${PROG} | cmp <(echo "-2") && echo "test#12 passed!" || true
+echo "a=3" | ./${PROG} | cmp <(echo "3") && echo "test#13 passed!" || true
+echo "a=3 a*2" | ./${PROG} | cmp <(printf "3\n6\n") && echo "test#14 passed!" || true
+echo "a=10 z=13 A+z" | ./${PROG} | cmp <(printf "10\n13\n23\n") && echo "test#15 passed!" || true
 
 make clean