[Core] Rename the grad-opposite-position() helper to opposite-position() and expose it as part of the core library.

doc-src/content/reference/compass/helpers/constants.haml

@@ -0,0 +1,31 @@
+--- 
+title: Compass Constant Helpers
+crumb: Constants
+framework: compass
+meta_description: Helper functions for working with constants.
+layout: core
+classnames:
+  - reference
+  - core
+  - helpers
+---
+%h1 Compass Constant Helpers
+
+:markdown
+  These helpers manipulate CSS Constants.
+
+#opposite-position.helper
+  %h3
+    %a(href="#opposite-position")
+      opposite-position($position)
+  .details
+    :markdown
+      Returns the opposition position for the position given. Examples:
+      
+          Input                              Output
+          -------------------------------    ------------
+          opposite-position(left)         => right
+          opposite-position(top)          => bottom
+          opposite-position(center)       => center
+          opposite-position(top left)     => bottom right
+          opposite-position(center right) => center left

frameworks/compass/stylesheets/compass/css3/_gradient.scss

@@ -37,7 +37,7 @@
   $background: unquote("");
   @if $image { $background : $image + unquote(", "); }
   $start: unquote($start);
-  $end: grad-opposite-position($start);
+  $end: opposite-position($start);
   @if $experimental-support-for-webkit {
     background-image: #{$background}-webkit-gradient(linear, grad-point($start), grad-point($end), grad-color-stops($color-stops));
   }

lib/compass/sass_extensions/functions.rb

@@ -1,7 +1,7 @@
 module Compass::SassExtensions::Functions
 end
 
-%w(selectors enumerate urls display inline_image image_size gradient_support font_files).each do |func|
+%w(selectors enumerate urls display inline_image image_size gradient_support font_files constants).each do |func|
   require "compass/sass_extensions/functions/#{func}"
 end
 
@@ -14,6 +14,7 @@ module Sass::Script::Functions
   include Compass::SassExtensions::Functions::ImageSize
   include Compass::SassExtensions::Functions::GradientSupport::Functions
   include Compass::SassExtensions::Functions::FontFiles
+  include Compass::SassExtensions::Functions::Constants
 end
 
 # Wierd that this has to be re-included to pick up sub-modules. Ruby bug?

lib/compass/sass_extensions/functions/constants.rb

@@ -0,0 +1,17 @@
+module Compass::SassExtensions::Functions::Constants
+  # returns the opposite position of a side or corner.
+  def opposite_position(position)
+    opposite = position.value.split(/ +/).map do |pos|
+      case pos
+      when "top" then "bottom"
+      when "bottom" then "top"
+      when "left" then "right"
+      when "right" then "left"
+      when "center" then "center"
+      else
+        raise Sass::SyntaxError, "Cannot determine the opposite of #{pos}"
+      end
+    end
+    Sass::Script::String.new(opposite.join(" "), position.type)
+  end
+end

lib/compass/sass_extensions/functions/gradient_support.rb

@@ -36,22 +36,6 @@ module Compass::SassExtensions::Functions::GradientSupport
   end
 
   module Functions
-    # returns the opposite position of a side or corner.
-    def grad_opposite_position(position)
-      opposite = position.value.split(/ +/).map do |pos|
-        case pos
-        when "top" then "bottom"
-        when "bottom" then "top"
-        when "left" then "right"
-        when "right" then "left"
-        when "center" then "center"
-        else
-          raise Sass::SyntaxError, "Cannot determine the opposite of #{pos}"
-        end
-      end
-      Sass::Script::String.new(opposite.join(" "))
-    end
-
     # returns color-stop() calls for use in webkit.
     def grad_color_stops(color_list)
       assert_list(color_list)