1 files changed, 104 insertions, 0 deletions
diff --git a/mrbgems/mruby-rational/mrblib/rational.rb b/mrbgems/mruby-rational/mrblib/rational.rb
new file mode 100644
index 000000000..c8614ecea
--- /dev/null
+++ b/mrbgems/mruby-rational/mrblib/rational.rb
@@ -0,0 +1,104 @@
+class Rational < Numeric
+  def inspect
+    "(#{to_s})"
+  end
+
+  def to_s
+    "#{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 + rhs.numerator * denominator, denominator * rhs.denominator)
+    elsif rhs.is_a? Integer
+      Rational(numerator + rhs * denominator, denominator)
+    elsif rhs.is_a? Numeric
+      (numerator + rhs * denominator) / denominator
+    end
+  end
+
+  def -(rhs)
+    if rhs.is_a? Rational
+      Rational(numerator * rhs.denominator - rhs.numerator * denominator, denominator * rhs.denominator)
+    elsif rhs.is_a? Integer
+      Rational(numerator - rhs * denominator, denominator)
+    elsif rhs.is_a? Numeric
+      (numerator - rhs * denominator) / denominator
+    end
+  end
+
+  def /(rhs)
+    if rhs.is_a? Rational
+      Rational(numerator * rhs.denominator, denominator * rhs.numerator)
+    elsif rhs.is_a? Integer
+      Rational(numerator, denominator * rhs)
+    elsif rhs.is_a? Numeric
+      numerator / rhs / denominator
+    end
+  end
+
+  def <=>(rhs)
+    if rhs.is_a?(Integral)
+      return numerator <=> rhs if denominator == 1
+      rhs = Rational(rhs)
+    end
+
+    case rhs
+    when Rational
+      (numerator * rhs.denominator - denominator * rhs.numerator) <=> 0
+    when Numeric
+      (rhs <=> self)&.-@
+    else
+      nil
+    end
+  end
+end
+
+class Numeric
+  def to_r
+    Rational(self, 1)
+  end
+end
+
+module Kernel
+  def Rational(numerator = 0, denominator = 1)
+    a = numerator
+    b = denominator
+    a, b = b, a % b until b == 0
+    Rational._new(numerator.div(a), denominator.div(a))
+  end
+end
+
+[:+, :-, :*, :/, :<=>, :==, :<, :<=, :>, :>=].each do |op|
+  Fixnum.instance_eval do
+    original_operator_name = "__original_operator_#{op}_rational"
+    alias_method original_operator_name, op
+    define_method op do |rhs|
+      if rhs.is_a? Rational
+        Rational(self).__send__(op, rhs)
+      else
+        __send__(original_operator_name, rhs)
+      end
+    end
+  end
+  Float.instance_eval do
+    original_operator_name = "__original_operator_#{op}_rational"
+    alias_method original_operator_name, op
+    define_method op do |rhs|
+      if rhs.is_a? Rational
+        rhs = rhs.to_f
+      end
+      __send__(original_operator_name, rhs)
+    end
+  end if Object.const_defined?(:Float)
+end