Refactors margin and padding transformers to dry up code

Author: zmoazeni

lib/csscss.rb

@@ -15,6 +15,8 @@
 require "csscss/parser/common"
 require "csscss/parser/color"
 require "csscss/parser/base"
+require "csscss/parser/multi_width_transformer"
+
 require "csscss/parser/background"
 require "csscss/parser/list_style"
 require "csscss/parser/margin"

lib/csscss/parser/margin.rb

@@ -24,35 +24,8 @@ class Parser < Parslet::Parser
       end
 
       class Transformer < Parslet::Transform
-        rule(margin: simple(:inherit)) {[]}
-
-        SIDE = proc {|side, value| Declaration.from_parser("margin-#{side}", value) }
-
-        rule(margin: {
-          top:simple(:top),
-          right:simple(:right),
-          bottom:simple(:bottom),
-          left:simple(:left)
-        }) {
-          values = [top, right, bottom, left].compact
-          case values.size
-          when 4
-            %w(top right bottom left).zip(values).map {|side, value| SIDE[side, value] }
-          when 3
-            %w(top right bottom).zip(values).map {|side, value| SIDE[side, value] }.tap do |declarations|
-              declarations << SIDE["left", values[1]]
-            end
-          when 2
-            %w(top right).zip(values).map {|side, value| SIDE[side, value] }.tap do |declarations|
-              declarations << SIDE["bottom", values[0]]
-              declarations << SIDE["left", values[1]]
-            end
-          when 1
-            %w(top right bottom left).map do |side|
-              SIDE[side, values[0]]
-            end
-          end
-        }
+        @property = :margin
+        extend MultiWidthTransformer
       end
     end
   end

lib/csscss/parser/multi_width_transformer.rb

@@ -0,0 +1,47 @@
+module Csscss
+  module Parser
+    module MultiWidthTransformer
+      def self.extended(base)
+        base.instance_eval do
+          extend ClassMethods
+
+          rule(@property => simple(:inherit)) {[]}
+
+          rule({@property => {
+            top:simple(:top),
+            right:simple(:right),
+            bottom:simple(:bottom),
+            left:simple(:left)
+          }}, &method(:transform_sides))
+        end
+      end
+
+      module ClassMethods
+        def side_declaration(side, value)
+          Declaration.from_parser("#{@property}-#{side}", value)
+        end
+
+        def transform_sides(context)
+          values = [context[:top], context[:right], context[:bottom], context[:left]].compact
+          case values.size
+          when 4
+            %w(top right bottom left).zip(values).map {|side, value| side_declaration(side, value) }
+          when 3
+            %w(top right bottom).zip(values).map {|side, value| side_declaration(side, value) }.tap do |declarations|
+              declarations << side_declaration("left", values[1])
+            end
+          when 2
+            %w(top right).zip(values).map {|side, value| side_declaration(side, value) }.tap do |declarations|
+              declarations << side_declaration("bottom", values[0])
+              declarations << side_declaration("left", values[1])
+            end
+          when 1
+            %w(top right bottom left).map do |side|
+              side_declaration(side, values[0])
+            end
+          end
+        end
+      end
+    end
+  end
+end

lib/csscss/parser/padding.rb

@@ -24,35 +24,8 @@ class Parser < Parslet::Parser
       end
 
       class Transformer < Parslet::Transform
-        rule(padding: simple(:inherit)) {[]}
-
-        SIDE = proc {|side, value| Declaration.from_parser("padding-#{side}", value) }
-
-        rule(padding: {
-          top:simple(:top),
-          right:simple(:right),
-          bottom:simple(:bottom),
-          left:simple(:left)
-        }) {
-          values = [top, right, bottom, left].compact
-          case values.size
-          when 4
-            %w(top right bottom left).zip(values).map {|side, value| SIDE[side, value] }
-          when 3
-            %w(top right bottom).zip(values).map {|side, value| SIDE[side, value] }.tap do |declarations|
-              declarations << SIDE["left", values[1]]
-            end
-          when 2
-            %w(top right).zip(values).map {|side, value| SIDE[side, value] }.tap do |declarations|
-              declarations << SIDE["bottom", values[0]]
-              declarations << SIDE["left", values[1]]
-            end
-          when 1
-            %w(top right bottom left).map do |side|
-              SIDE[side, values[0]]
-            end
-          end
-        }
+        @property = :padding
+        extend MultiWidthTransformer
       end
     end
   end