Refactored background-image mixin plus better compact function written

in ruby. Works with rails 3.1

app/assets/stylesheets/_bourbon.css.scss

@@ -1,12 +1,11 @@
 // Custom Functions
-@import "functions/compact";
 @import "functions/golden-ratio";
-@import "functions/linear-gradient";
 @import "functions/tint-shade";
+@import "functions/gradient";
 
 // CSS3 Mixins
 @import "css3/animation";
-@import "css3/backround-image";
+@import "css3/background-image";
 @import "css3/border-radius";
 @import "css3/box-shadow";
 @import "css3/box-sizing";

app/assets/stylesheets/css3/_background-image.css.scss

@@ -7,54 +7,96 @@
   $image-7: false, $image-8: false,
   $image-9: false, $image-10: false
 ) {
-  $images: $image-1, $image-2,
+  $images: compact($image-1, $image-2,
            $image-3, $image-4,
            $image-5, $image-6,
            $image-7, $image-8,
-           $image-9, $image-10;
+           $image-9, $image-10);
 
   $assets:    false;
   $gradients: false;
-  $all-assets:    0;
-  $all-gradients: 0;
+  $count: 0;
 
-  @each $image in $images {
-    // Detect images passed into mixin and join into a list.
-    @if type-of($image) == string {
-      $assets: join($assets, $image);
+  //Find all asset images in list
+  @for $i from 1 through length($images) {
+    $type: type-of(nth($images, $i));
+
+    @if $type == list {
+      $count: $count + 1;
     }
-    // Detect gradients passed into mixin and join into a list.
-    @else if type-of($image) == list {
-      $gradients: join($gradients, $image);
+
+    @else if $type == string {
+      @if $assets == false {
+        $assets: nth($images, $i);
+      }
+
+      @else {
+        $assets: join($assets, nth($images, $i), comma);
+      }
     }
   }
 
-  // Remove false value
-  $all-assets: nth($assets, 2);
-  @for $n from 3 through length($assets) {
-    @if $n {
-      $all-assets: $all-assets, nth($assets, $n);
+  // Find all gradients in list
+  @for $i from 1 through length($images) {
+    $type: type-of(nth($images, $i));
+
+    @if $type == list {
+      @if $gradients == false {
+        $gradients: nth($images, $i);
+      }
+      @else {
+        $gradients: $gradients, nth($images, $i);
+      }
     }
   }
 
-  @if length($gradients) >= 2 {
-    // Remove flase value
-    $all-gradients: nth($gradients, 2);
-    @for $n from 3 through length($gradients) {
-      @if $n {
-        $all-gradients: $all-gradients, nth($gradients, $n);
+  @function render-gradients($gradients, $vendor: false) {
+    @if $count == 1 {
+      $vendor-gradients: false;
+      @if $vendor {
+        $vendor-gradients: -#{$vendor}-linear-gradient($gradients);
       }
+      @else if $vendor == false {
+        $vendor-gradients: linear-gradient($gradients);
+      }
+      @return $vendor-gradients;
+    }
+
+    @else if $count >= 2 {
+      $vendor-gradients: false;
+      @for $i from 1 through length($gradients) {
+        @if $vendor {
+          @if $vendor-gradients == false {
+            $vendor-gradients: -#{$vendor}-linear-gradient(nth($gradients, $i));
+          }
+          @else {
+            $vendor-gradients: $vendor-gradients, -#{$vendor}-linear-gradient(nth($gradients, $i));
+          }
+        }
+        @else if $vendor == false {
+          @if $vendor-gradients {
+            $vendor-gradients: linear-gradient(nth($gradients, $i));
+          }
+          @else {
+            $vendor-gradients: $vendor-gradients, linear-gradient(nth($gradients, $i));
+          }
+        }
+      }
+      @return $vendor-gradients;
     }
   }
-  @if length($gradients) >= 2 {
-    background-image: $all-assets, -webkit-linear-gradient($all-gradients);
-    background-image: $all-assets,   -moz-linear-gradient($all-gradients);
-    background-image: $all-assets,    -ms-linear-gradient($all-gradients);
-    background-image: $all-assets,     -o-linear-gradient($all-gradients);
-    background-image: $all-assets,        linear-gradient($all-gradients);
+
+
+  @if $count >= 1 {
+    background-image: $assets, render-gradients($gradients, webkit);
+    background-image: $assets, render-gradients($gradients, moz);
+    background-image: $assets, render-gradients($gradients, ms);
+    background-image: $assets, render-gradients($gradients, o);
+    background-image: $assets, render-gradients($gradients);
+
   }
   @else {
-    background-image: $all-assets;
+    background-image: $assets;
   }
 }
 //Examples:

app/assets/stylesheets/functions/_gradient.css.scss

@@ -0,0 +1,19 @@
+@function gradient($pos: top, $G1: false, $G2: false,
+                       $G3: false, $G4: false,
+                       $G5: false, $G6: false,
+                       $G7: false, $G8: false,
+                       $G9: false, $G10: false) {
+  // Detect what type of value exists in $pos
+  $pos-type: type-of(nth($pos, 1));
+
+  // If $pos is missing from mixin, reassign vars and add default position
+  @if $pos-type == color or transparent {
+    $G10: $G9; $G9: $G8; $G8: $G7; $G7: $G6; $G6: $G5;
+     $G5: $G4; $G4: $G3; $G3: $G2; $G2: $G1; $G1: $pos;
+    $pos: top; // Default position
+  }
+
+  $full: compact($G1, $G2, $G3, $G4, $G5, $G6, $G7, $G8, $G9, $G10);
+  @return join($pos, $full, comma);
+  //@return $pos, $full;
+}

lib/bourbon.rb

@@ -11,3 +11,5 @@ class Railtie < ::Rails::Railtie
     end
   end
 end
+
+require "bourbon/sass_extensions"

lib/bourbon/sass_extensions.rb

@@ -0,0 +1,4 @@
+module Bourbon::SassExtensions
+end
+
+require "bourbon/sass_extensions/functions"

lib/bourbon/sass_extensions/functions.rb

@@ -0,0 +1,15 @@
+module Bourbon::SassExtensions::Functions
+end
+
+%w(compact).each do |func|
+  require "bourbon/sass_extensions/functions/#{func}"
+end
+
+module Sass::Script::Functions
+  include Bourbon::SassExtensions::Functions::Compact
+end
+
+# Wierd that this has to be re-included to pick up sub-modules. Ruby bug?
+class Sass::Script::Functions::EvaluationContext
+  include Sass::Script::Functions
+end

lib/bourbon/sass_extensions/functions/compact.rb

@@ -0,0 +1,13 @@
+# Compact function pulled from compass
+module Bourbon::SassExtensions::Functions::Compact
+
+  def compact(*args)
+    sep = :comma
+    if args.size == 1 && args.first.is_a?(Sass::Script::List)
+      args = args.first.value
+      sep = args.first.separator
+    end
+    Sass::Script::List.new(args.reject{|a| !a.to_bool}, sep)
+  end
+
+end