rational.c: implement `Rational#*` in C.

mrbgems/mruby-rational/mrblib/rational.rb

@@ -7,16 +7,6 @@ class Rational < Numeric
     "#{numerator}/#{denominator}"
   end
 
-  def *(rhs)
-    if rhs.is_a? Rational
-      Rational(numerator * rhs.numerator, denominator * rhs.denominator)
-    elsif rhs.is_a? Integer
-      Rational(numerator * rhs, denominator)
-    elsif rhs.is_a? Numeric
-      numerator * rhs / denominator
-    end
-  end
-
   def /(rhs)
     if rhs.is_a? Rational
       Rational(numerator * rhs.denominator, denominator * rhs.numerator)

mrbgems/mruby-rational/src/rational.c

@@ -507,6 +507,42 @@ rational_sub(mrb_state *mrb, mrb_value x)
   }
 }
 
+static mrb_value
+rational_mul(mrb_state *mrb, mrb_value x)
+{
+  struct mrb_rational *p1 = rational_ptr(mrb, x);
+  mrb_value y = mrb_get_arg1(mrb);
+
+  switch (mrb_type(y)) {
+  case MRB_TT_INTEGER:
+    {
+      mrb_int z = mrb_integer(y);
+      if (mrb_int_mul_overflow(p1->numerator, z, &z)) rat_overflow(mrb);
+      return rational_new_i(mrb, z, p1->denominator);
+    }
+  case MRB_TT_RATIONAL:
+    {
+      struct mrb_rational *p2 = rational_ptr(mrb, y);
+      mrb_int a, b;
+
+      if (mrb_int_mul_overflow(p1->numerator, p2->numerator, &a)) rat_overflow(mrb);
+      if (mrb_int_mul_overflow(p1->denominator, p2->denominator, &b)) rat_overflow(mrb);
+      return rational_new_i(mrb, a, b);
+    }
+
+#ifndef MRB_NO_FLOAT
+  case MRB_TT_FLOAT:
+    {
+      mrb_float z = p1->numerator * mrb_float(y);
+      return mrb_float_value(mrb, mrb_num_div_flo(mrb, z, (mrb_float)p1->denominator));
+  }
+#endif
+
+  default:
+    return mrb_funcall_id(mrb, y, MRB_OPSYM(add), 1, x);
+  }
+}
+
 mrb_int mrb_num_div_int(mrb_state *, mrb_int, mrb_int);
 
 /* 15.2.8.3.4  */
@@ -594,6 +630,7 @@ void mrb_mruby_rational_gem_init(mrb_state *mrb)
   mrb_define_method(mrb, rat, "-@", rational_minus, MRB_ARGS_NONE());
   mrb_define_method(mrb, rat, "+", rational_add, MRB_ARGS_REQ(1));
   mrb_define_method(mrb, rat, "-", rational_sub, MRB_ARGS_REQ(1));
+  mrb_define_method(mrb, rat, "*", rational_mul, MRB_ARGS_REQ(1));
   mrb_define_method(mrb, mrb->integer_class, "to_r", fix_to_r, MRB_ARGS_NONE());
   mrb_define_method(mrb, mrb->integer_class, "/", int_div, MRB_ARGS_REQ(1)); /* overrride */
   mrb_define_method(mrb, mrb->integer_class, "quo", int_quo, MRB_ARGS_REQ(1)); /* overrride */