Add direction mixin

- Closes #200

app/assets/stylesheets/_neat.scss

@@ -21,3 +21,4 @@
 @import "grid/to-deprecate";
 @import "grid/visual-grid";
 @import "grid/display";
+@import "grid/direction";

app/assets/stylesheets/functions/_private.scss

@@ -10,9 +10,9 @@
 
 // Contains display value
 @function contains-display-value($query) {
-  @return belongs-to(table, $query) 
-       or belongs-to(block, $query) 
-       or belongs-to(inline-block, $query) 
+  @return belongs-to(table, $query)
+       or belongs-to(block, $query)
+       or belongs-to(inline-block, $query)
        or belongs-to(inline, $query);
 }
 
@@ -81,7 +81,7 @@
 // Layout direction
 @function get-direction($layout, $default) {
   $direction: nil;
-  
+
   @if $layout == LTR or $layout == RTL {
     $direction: direction-from-layout($layout);
   } @else {

app/assets/stylesheets/grid/_direction.scss

@@ -0,0 +1,33 @@
+/**
+ * Changes the direction property used by other mixins called in the code block argument.
+ *
+ * @param {String} $direction (left-to-right) - Layout direction to be used within the block. Can be `left-to-right` or `right-to-left`.
+ *
+ * @example scss
+ *   @include direction(right-to-left) {
+ *    .right-to-left-block {
+ *      @include span-columns(6);
+ *     }
+ *   }
+ *
+ * @example css
+ *   // CSS
+ *   .right-to-left-block {
+ *     float: right;
+ *      ...
+ *   }
+ */
+
+@mixin direction($direction: left-to-right) {
+  $scope-direction: $layout-direction;
+
+  @if $direction == left-to-right {
+    $layout-direction: LTR !global;
+  } @else if $direction == right-to-left {
+    $layout-direction: RTL !global;
+  }
+
+  @content;
+
+  $layout-direction: $scope-direction !global;
+}

app/assets/stylesheets/grid/_row.scss

@@ -1,4 +1,8 @@
 @mixin row($display: default, $direction: $default-layout-direction) {
+  @if $direction != $default-layout-direction {
+    @warn "The $direction argument will be deprecated in future versions in favor of the direction(){...} mixin."
+  }
+
   $layout-direction: $direction !global;
 
   @if $display != default {

spec/neat/direction_spec.rb

@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+describe "@include direction() {...}" do
+  before(:all) do
+    ParserSupport.parse_file("direction")
+  end
+
+  context "with no argument" do
+    it "uses default direction setting" do
+      expect('.default-block').to have_rule('float: left')
+    end
+  end
+
+  context "whith argument (right-to-left)" do
+    it "changes direction setting inside the block" do
+      expect('.right-to-left-block').to have_rule('float: right')
+    end
+  end
+end

test/direction.scss

@@ -0,0 +1,13 @@
+@import 'setup';
+
+@include direction() {
+  .default-block {
+    @include span-columns(6);
+  }
+}
+
+@include direction(right-to-left) {
+  .right-to-left-block {
+    @include span-columns(6);
+  }
+}