Implement part of `Rational` in C.

mrbgems/mruby-rational/mrblib/rational.rb

@@ -2,29 +2,10 @@ class Rational < Numeric
   # Override #<, #<=, #>, #>= in Numeric
   prepend Comparable
 
-  def initialize(numerator = 0, denominator = 1)
-    @numerator = numerator
-    @denominator = denominator
-
-    _simplify
-  end
-
   def inspect
     "(#{to_s})"
   end
 
-  def to_f
-    @numerator.to_f / @denominator.to_f
-  end
-
-  def to_i
-    to_f.to_i
-  end
-
-  def to_r
-    self
-  end
-
   def to_s
     "#{numerator}/#{denominator}"
   end
@@ -86,24 +67,24 @@ class Rational < Numeric
       nil
     end
   end
+end
 
-  def negative?
-    numerator.negative?
-  end
-
-  def _simplify
-    a = numerator
-    b = denominator
-    a, b = b, a % b until b.zero?
-    @numerator = @numerator.div(a)
-    @denominator = @denominator.div(a)
+class << Numeric
+  def to_r
+    Rational(self, 1)
   end
+end
 
-  attr_reader :numerator, :denominator
+class << Rational
+  alias_method :_new, :new
+  undef_method :new
 end
 
 def Rational(numerator = 0, denominator = 1)
-  Rational.new(numerator, denominator)
+  a = numerator
+  b = denominator
+  a, b = b, a % b until b.zero?
+  Rational._new(numerator.div(a), denominator.div(a))
 end
 
 [:+, :-, :*, :/, :<=>, :==, :<, :<=, :>, :>=].each do |op|

mrbgems/mruby-rational/src/rational.c

+#include <mruby.h>
+#include <mruby/class.h>
+#include <mruby/string.h>
+#include <mruby/istruct.h>
+
+struct mrb_rational {
+  mrb_int numerator;
+  mrb_int denominator;
+};
+
+static struct mrb_rational*
+rational_ptr(mrb_value v)
+{
+  return (struct mrb_rational*)mrb_istruct_ptr(v);
+}
+
+static mrb_value
+rational_numerator(mrb_state *mrb, mrb_value self)
+{
+  struct mrb_rational *p = rational_ptr(self);
+  return mrb_fixnum_value(p->numerator);
+}
+
+static mrb_value
+rational_denominator(mrb_state *mrb, mrb_value self)
+{
+  struct mrb_rational *p = rational_ptr(self);
+  return mrb_fixnum_value(p->denominator);
+}
+
+static mrb_value
+rational_initialize(mrb_state *mrb, mrb_value self)
+{
+  struct mrb_rational *p = rational_ptr(self);
+  mrb_get_args(mrb, "ii", &p->numerator, &p->denominator);
+  return self;
+}
+
+static mrb_value
+rational_to_f(mrb_state *mrb, mrb_value self)
+{
+  struct mrb_rational *p = rational_ptr(self);
+  mrb_float f = (mrb_float)p->numerator / (mrb_float)p->denominator;
+
+  return mrb_float_value(mrb, f);
+}
+
+static mrb_value
+rational_to_i(mrb_state *mrb, mrb_value self)
+{
+  struct mrb_rational *p = rational_ptr(self);
+  return mrb_fixnum_value(p->numerator / p->denominator);
+}
+
+static mrb_value
+rational_to_r(mrb_state *mrb, mrb_value self)
+{
+  return self;
+}
+
+static mrb_value
+rational_negative_p(mrb_state *mrb, mrb_value self)
+{
+  struct mrb_rational *p = rational_ptr(self);
+  if (p->numerator < 0) {
+    return mrb_true_value();
+  }
+  return mrb_false_value();
+}
+
+void mrb_mruby_rational_gem_init(mrb_state *mrb)
+{
+  struct RClass *rat;
+
+  mrb_assert(sizeof(struct mrb_rational) < ISTRUCT_DATA_SIZE);
+  rat = mrb_define_class(mrb, "Rational", mrb_class_get(mrb, "Numeric"));
+  MRB_SET_INSTANCE_TT(rat, MRB_TT_ISTRUCT);
+  mrb_define_method(mrb, rat, "numerator", rational_numerator, MRB_ARGS_NONE());
+  mrb_define_method(mrb, rat, "denominator", rational_denominator, MRB_ARGS_NONE());
+  mrb_define_method(mrb, rat, "initialize", rational_initialize, MRB_ARGS_REQ(2));
+  mrb_define_method(mrb, rat, "to_f", rational_to_f, MRB_ARGS_NONE());
+  mrb_define_method(mrb, rat, "to_i", rational_to_i, MRB_ARGS_NONE());
+  mrb_define_method(mrb, rat, "to_r", rational_to_r, MRB_ARGS_NONE());
+  mrb_define_method(mrb, rat, "negative?", rational_negative_p, MRB_ARGS_NONE());
+}
+
+void
+mrb_mruby_rational_gem_final(mrb_state* mrb)
+{
+}