Revert "Revert "[close #331] Smarter entry lookup""

This reverts commit e295278.

lib/sprockets.rb

@@ -162,6 +162,7 @@ module Sprockets
   require 'sprockets/eco_processor'
   require 'sprockets/ejs_processor'
   require 'sprockets/jst_processor'
+  register_mime_type 'application/javascript+function', extensions: []
   register_mime_type 'text/eco', extensions: ['.eco', '.jst.eco']
   register_mime_type 'text/ejs', extensions: ['.ejs', '.jst.ejs']
   register_transformer 'text/eco', 'application/javascript+function', EcoProcessor

lib/sprockets/path_utils.rb

@@ -180,16 +180,30 @@ def match_path_extname(path, extensions)
     # Returns an Array of [String path, Object value] matches.
     def find_matching_path_for_extensions(path, basename, extensions)
       matches = []
-      entries(path).each do |entry|
-        next unless File.basename(entry).start_with?(basename)
-        extname, value = match_path_extname(entry, extensions)
-        if basename == entry.chomp(extname)
-          filename = File.join(path, entry)
-          if file?(filename)
-            matches << [filename, value]
+      # Requires a file touch for each extension
+      # In the case where lots of extensions are given, it may be faster to search the directory
+      if extensions.length < 3
+        extensions.each do |(extension, mime_type)|
+          file = File.join(path, basename + extension)
+          matches << [file, mime_type] if File.exist?(file)
+        end
+      end
+
+      # Used when files don't have registered mime types or
+      # when a large number of extensions would require too many file touches.
+      if matches.empty?
+        entries(path).each do |entry|
+          next unless File.basename(entry).start_with?(basename)
+          extname, value = match_path_extname(entry, extensions)
+          if basename == entry.chomp(extname)
+            filename = File.join(path, entry)
+            if file?(filename)
+              matches << [filename, value]
+            end
           end
         end
       end
+
       matches
     end
 

lib/sprockets/resolve.rb

@@ -180,7 +180,20 @@ def resolve_under_paths(paths, logical_name, accepts)
           method(:resolve_alts_under_path),
           method(:resolve_index_under_path)
         ]
-        mime_exts = config[:mime_exts]
+
+        mime_exts = {}
+        accepts.each do |mime, version|
+          if '*/*'.freeze == mime
+            mime_exts = config[:mime_exts]
+            break
+          end
+
+          mime_hash = config[:mime_types][mime]
+          raise "No valid mime type found for #{ mime.inspect }. Valid types #{ config[:mime_types].keys.inspect }" unless mime_hash
+          mime_hash[:extensions].each do |extension|
+            mime_exts[extension] = mime
+          end
+        end
 
         paths.each do |load_path|
           candidates = []

test/test_path_utils.rb

@@ -44,7 +44,7 @@ def test_entries
       "source-maps",
       "symlink"
     ], entries(File.expand_path("../fixtures", __FILE__))
-    
+
     [ ['a', 'b'], ['a', 'b', '.', '..'] ].each do |dir_contents|
       Dir.stub :entries, dir_contents do
         assert_equal ['a', 'b'], entries(Dir.tmpdir)
@@ -188,7 +188,7 @@ def test_find_matching_path_for_extensions
     assert_equal [
       ["#{dirname}/hello.jst.ejs", "application/ejs"],
       ["#{dirname}/hello.txt", "text/plain"]
-    ], find_matching_path_for_extensions(dirname, "hello", extensions)
+    ].sort, find_matching_path_for_extensions(dirname, "hello", extensions).sort
 
   end