Use char instead of int for FSA rule input

lib/include/fsa.h

@@ -8,14 +8,9 @@
 
 #include <stdbool.h>
 
-#define CHAR_COUNT 256
-#define ALPHABET_SIZE (CHAR_COUNT + 1)
-
-// Use one more than any valid char to represent empty string
-#define EPSILON CHAR_COUNT
-
 typedef struct {
-	int input, next;
+	int next;
+	char input;
 } fsa_rule_t;
 
 typedef struct {
@@ -33,6 +28,6 @@ void fsa_init(fsa_t *fsa);
 void fsa_free(const fsa_t *fsa);
 
 int fsa_add_state(fsa_t *fsa);
-void fsa_add_rule(fsa_t *fsa, int from, int to, int input);
+void fsa_add_rule(fsa_t *fsa, int from, int to, char input);
 
 #endif