Make compressors lazily load.

2 files changed, 25 insertions, 2 deletions

diff --git a/actionpack/lib/sprockets/compressors.rb b/actionpack/lib/sprockets/compressors.rb
new file mode 100644
index 0000000000..6544953df4
--- /dev/null
+++ b/actionpack/lib/sprockets/compressors.rb
@@ -0,0 +1,21 @@
+module Sprockets
+  class NullCompressor
+    def compress(content)
+      content
+    end
+  end
+
+  class LazyCompressor
+    def initialize(&block)
+      @block = block
+    end
+
+    def compressor
+      @compressor ||= @block.call || NullCompressor.new
+    end
+
+    def compress(content)
+      compressor.compress(content)
+    end
+  end
+end
\ No newline at end of file
diff --git a/actionpack/lib/sprockets/railtie.rb b/actionpack/lib/sprockets/railtie.rb
index d1e97c594e..970773c6a4 100644
--- a/actionpack/lib/sprockets/railtie.rb
+++ b/actionpack/lib/sprockets/railtie.rb
@@ -1,5 +1,7 @@
 module Sprockets
   autoload :Helpers, "sprockets/helpers"
+  autoload :LazyCompressor, "sprockets/compressors"
+  autoload :NullCompressor, "sprockets/compressors"
 
   # TODO: Get rid of config.assets.enabled
   class Railtie < ::Rails::Railtie
@@ -66,8 +68,8 @@ module Sprockets
         if assets.compress
           # temporarily hardcode default JS compressor to uglify. Soon, it will work
           # the same as SCSS, where a default plugin sets the default.
-          env.js_compressor  = expand_js_compressor(assets.js_compressor || :uglifier)
-          env.css_compressor = expand_css_compressor(assets.css_compressor)
+          env.js_compressor  = LazyCompressor.new { expand_js_compressor(assets.js_compressor || :uglifier) }
+          env.css_compressor = LazyCompressor.new { expand_css_compressor(assets.css_compressor) }
         end
 
         env