Implement some bonus marks

chapter_08/lispy.c

@@ -34,17 +34,20 @@ void add_history(char* unused) {}
 /* Declare new lval struct */
 typedef struct {
     int type;
-    long num;
+    union {
+        long num;
+        double dec;
+    };
     int err;
 } lval;
 
 
 /* Create enumeration of possible lval types */
-enum {LVAL_NUM, LVAL_ERR};
+enum lval_types {LVAL_NUM, LVAL_DEC, LVAL_ERR};
 
 
 /* Create enumeration of possible error types */
-enum {LERR_DIV_ZERO, LERR_BAD_OP, LERR_BAD_NUM};
+enum lval_errors {LERR_DIV_ZERO, LERR_BAD_OP, LERR_BAD_NUM};
 
 
 /* Create a new number of type lval */
@@ -56,6 +59,15 @@ lval lval_num(long x) {
 }
 
 
+/* Create a new decimal of type lval */
+lval lval_dec(double x) {
+    lval v;
+    v.type = LVAL_DEC;
+    v.dec = x;
+    return v;
+}
+
+
 /* Create a new error type lval */
 lval lval_err(int x) {
     lval v;
@@ -73,6 +85,11 @@ void lval_print(lval v) {
         case LVAL_NUM:
             printf("%li", v.num);
             break;
+        /* In the case the type is a decimal print it
+           Then break out of the switch */
+        case LVAL_DEC:
+            printf("%.2f", v.dec);
+            break;
         /* In the case the type is an error */
         case LVAL_ERR:
             /* Check what type of error it is & print it */
@@ -127,19 +144,37 @@ lval eval_op(lval x, char* op, lval y) {
     }
 
     /* Otherwise do maths on the number values */
-
-    if (strcmp(op, "+") == 0) {return lval_num(x.num + y.num);}
-    if (strcmp(op, "-") == 0) {return lval_num(x.num - y.num);}
-    if (strcmp(op, "*") == 0) {return lval_num(x.num * y.num);}
-    if (strcmp(op, "/") == 0) {
-        /* If second operand is zero return error */
-        return y.num == 0 ? lval_err(LERR_DIV_ZERO)
-                          : lval_num(x.num / y.num);
+    if (x.type == LVAL_NUM && y.type == LVAL_NUM) {
+        if (strcmp(op, "+") == 0) {return lval_num(x.num + y.num);}
+        if (strcmp(op, "-") == 0) {return lval_num(x.num - y.num);}
+        if (strcmp(op, "*") == 0) {return lval_num(x.num * y.num);}
+        if (strcmp(op, "/") == 0) {
+            /* If second operand is zero return error */
+            return y.num == 0 ? lval_err(LERR_DIV_ZERO)
+                              : lval_num(x.num / y.num);
+        }
+        if (strcmp(op, "%") == 0) {return lval_num(x.num % y.num);}
+        if (strcmp(op, "^") == 0) {return lval_num(pow(x.num, y.num));}
+        if (strcmp(op, "min") == 0) {return lval_num(min(x.num, y.num));}
+        if (strcmp(op, "max") == 0) {return lval_num(max(x.num, y.num));}
+    } else {
+        /* Cast integer number into double if necessary */
+        double a = x.type == LVAL_NUM ? (double) x.num : x.dec;
+        double b = y.type == LVAL_NUM ? (double) y.num : y.dec;
+        /* Perform all operations on double */
+        if (strcmp(op, "+") == 0) {return lval_dec(a + b);}
+        if (strcmp(op, "-") == 0) {return lval_dec(a - b);}
+        if (strcmp(op, "*") == 0) {return lval_dec(a * b);}
+        if (strcmp(op, "/") == 0) {
+            /* If second operand is zero return error */
+            return b == 0 ? lval_err(LERR_DIV_ZERO)
+                          : lval_dec(a / b);
+        }
+        if (strcmp(op, "%") == 0) {return lval_dec(fmod(a, b));}
+        if (strcmp(op, "^") == 0) {return lval_dec(pow(a, b));}
+        if (strcmp(op, "min") == 0) {return lval_dec(fmin(a, b));}
+        if (strcmp(op, "max") == 0) {return lval_dec(fmax(a, b));}
     }
-    if (strcmp(op, "%") == 0) {return lval_num(x.num % y.num);}
-    if (strcmp(op, "^") == 0) {return lval_num(pow(x.num, y.num));}
-    if (strcmp(op, "min") == 0) {return lval_num(min(x.num, y.num));}
-    if (strcmp(op, "max") == 0) {return lval_num(max(x.num, y.num));}
 
     return lval_err(LERR_BAD_OP);
 }
@@ -150,8 +185,14 @@ lval eval(mpc_ast_t* t) {
     if (strstr(t->tag, "number")) {
         /* Check if there is some error in conversion */
         errno = 0;
-        long x = strtol(t->contents, NULL, 10);
-        return errno != ERANGE ? lval_num(x) : lval_err(LERR_BAD_NUM);
+        /* Check for decimal or integer number */
+        if (strstr(t->contents, ".")) {
+            double x = strtof(t->contents, NULL);
+            return errno != ERANGE ? lval_dec(x) : lval_err(LERR_BAD_NUM);
+        } else {
+            long x = strtol(t->contents, NULL, 10);
+            return errno != ERANGE ? lval_num(x) : lval_err(LERR_BAD_NUM);
+        }
     }
 
     /* The operator is always second child */
@@ -182,7 +223,7 @@ int main(int argc, char const *argv[]) {
     /* Define them with the following language */
     mpca_lang(MPCA_LANG_DEFAULT,
         "                                                       \
-            number   : /-?[0-9]+/ ;                             \
+            number   : /-?[0-9]+([.][0-9]*|[0-9]*)/ ;           \
             operator : '+' | '-' | '*' | '/' | '%' | '^' |      \
             \"min\" | \"max\" ;                                 \
             expr     : <number> | '(' <operator> <expr>+ ')' ;  \