Implements border_style parsing

Per specs on http://www.w3.org/TR/CSS21/box.html#propdef-border-style
http://www.w3.org/TR/CSS/

Author: zmoazeni

lib/csscss.rb

@@ -23,4 +23,5 @@
 require "csscss/parser/padding"
 require "csscss/parser/border_width"
 require "csscss/parser/border_color"
+require "csscss/parser/border_style"
 

lib/csscss/parser/border_style.rb

@@ -0,0 +1,41 @@
+module Csscss
+  module Parser
+    module BorderStyle
+      extend Parser::Base
+
+      class Parser < Parslet::Parser
+        include Common
+
+        rule(:border_style_side) {
+          symbol_list(%w(none hidden dotted dashed solid
+                         double groove ridge inset outset
+                      ))
+        }
+
+        rule(:border_style) {
+          (
+           symbol("inherit") >> eof | (
+             border_style_side.maybe.as(:top)    >>
+             border_style_side.maybe.as(:right)  >>
+             border_style_side.maybe.as(:bottom) >>
+             border_style_side.maybe.as(:left)
+           )
+          ).as(:border_style)
+        }
+
+        root(:border_style)
+      end
+
+      class Transformer < Parslet::Transform
+        @property = :border_style
+        extend MultiSideTransformer
+
+        class << self
+          def side_declaration(side, value)
+            Declaration.from_parser("border-#{side}-style", value)
+          end
+        end
+      end
+    end
+  end
+end

test/csscss/parser/border_style_test.rb

@@ -0,0 +1,30 @@
+require "test_helper"
+
+module Csscss::Parser
+  module BorderStyle
+    describe BorderStyle do
+      include CommonParserTests
+
+      before do
+        @parser = Parser.new
+        @trans = Transformer.new
+      end
+
+      it "converts shorthand rules to longhand" do
+        trans("none dashed solid ridge").must_equal([
+          dec("border-top-style", "none"),
+          dec("border-right-style", "dashed"),
+          dec("border-bottom-style", "solid"),
+          dec("border-left-style", "ridge")
+        ])
+
+        trans("none dashed").must_equal([
+          dec("border-top-style", "none"),
+          dec("border-right-style", "dashed"),
+          dec("border-bottom-style", "none"),
+          dec("border-left-style", "dashed")
+        ])
+      end
+    end
+  end
+end