lib/dydx/algebra/operator/parts/base.rb in dydx-0.0.4 vs lib/dydx/algebra/operator/parts/base.rb in dydx-0.0.5

@@ -1,26 +1,40 @@
 module Dydx
   module Algebra
     module Operator
       module Parts
         module Base
-          %w(+ - * / ^).each do |operator|
+          %w(+ * ^).map(&:to_sym).each do |operator|
             define_method(operator) do |x|
-              if self == x && operator != '^'
+              if self == x && operator != :^
                 case operator
-                when '+'
+                when :+
                   _(2) * self
-                when '-'
-                  _(0)
-                when '*'
+                when :*
                   self ^ _(2)
-                when '/'
-                  _(1)
                 end
+              elsif %w(+ *).map(&:to_sym).include?(operator) && x.send("#{to_str(operator)}?")
+                if combinable?(x.f, operator)
+                  send(operator, x.f).send(operator, x.g)
+                elsif combinable?(x.g, operator)
+                  send(operator, x.g).send(operator, x.f)
+                else
+                  ::Algebra::Formula.new(self, x, operator.to_sym)
+                end
+              elsif x.subtrahend? && %w(* ^).map(&:to_sym).include?(operator)
+                inverse(::Algebra::Formula.new(self, x.x, operator.to_sym), :+)
               else
                 ::Algebra::Formula.new(self, x, operator.to_sym)
               end
             end
+          end
+
+          def to_str(operator)
+            {
+              addition:       :+,
+              multiplication: :*,
+              exponentiation: :^
+            }.key(operator)
           end
         end
       end
     end
   end