Actually add an abstract class, so it is easier to get rid of old asset paths in the future.

1 files changed, 80 insertions, 0 deletions

diff --git a/actionpack/lib/action_view/helpers/asset_paths.rb b/actionpack/lib/action_view/helpers/asset_paths.rb
new file mode 100644
index 0000000000..55a4c442fd
--- /dev/null
+++ b/actionpack/lib/action_view/helpers/asset_paths.rb
@@ -0,0 +1,80 @@
+require 'active_support/core_ext/file'
+require 'action_view/helpers/asset_paths'
+
+module ActionView
+  module Helpers
+
+    class AssetPaths #:nodoc:
+      attr_reader :config, :controller
+
+      def initialize(config, controller)
+        @config = config
+        @controller = controller
+      end
+
+      # Add the extension +ext+ if not present. Return full URLs otherwise untouched.
+      # Prefix with <tt>/dir/</tt> if lacking a leading +/+. Account for relative URL
+      # roots. Rewrite the asset path for cache-busting asset ids. Include
+      # asset host, if configured, with the correct request protocol.
+      def compute_public_path(source, dir, ext = nil, include_host = true)
+        source = source.to_s
+        return source if is_uri?(source)
+
+        source = rewrite_extension(source, dir, ext) if ext
+        source = "/#{dir}/#{source}" unless source[0] == ?/
+        source = rewrite_asset_path(source, dir)
+
+        if controller && include_host
+          has_request = controller.respond_to?(:request)
+          source = rewrite_host_and_protocol(source, has_request)
+        end
+
+        source
+      end
+
+      def is_uri?(path)
+        path =~ %r{^[-a-z]+://|^cid:}
+      end
+
+    private
+
+      def rewrite_extension(source, dir, ext)
+        raise NotImplementedError
+      end
+
+      def rewrite_asset_path(source, path = nil)
+        raise NotImplementedError
+      end
+
+      def rewrite_host_and_protocol(source, has_request)
+        host = compute_asset_host(source)
+        if has_request && host && !is_uri?(host)
+          host = "#{controller.request.protocol}#{host}"
+        end
+        "#{host}#{source}"
+      end
+
+      # Pick an asset host for this source. Returns +nil+ if no host is set,
+      # the host if no wildcard is set, the host interpolated with the
+      # numbers 0-3 if it contains <tt>%d</tt> (the number is the source hash mod 4),
+      # or the value returned from invoking the proc if it's a proc or the value from
+      # invoking call if it's an object responding to call.
+      def compute_asset_host(source)
+        if host = config.asset_host
+          if host.is_a?(Proc) || host.respond_to?(:call)
+            case host.is_a?(Proc) ? host.arity : host.method(:call).arity
+            when 2
+              request = controller.respond_to?(:request) && controller.request
+              host.call(source, request)
+            else
+              host.call(source)
+            end
+          else
+            (host =~ /%d/) ? host % (source.hash % 4) : host
+          end
+        end
+      end
+    end
+
+  end
+end
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