Provide a dir => extension API to file update checker.

activesupport/lib/active_support/file_update_checker.rb

@@ -1,3 +1,6 @@
+require "active_support/core_ext/array/wrap"
+require "active_support/core_ext/array/extract_options"
+
 module ActiveSupport
   # This class is responsible to track files and invoke the given block
   # whenever one of these files are changed. For example, this class
@@ -15,15 +18,34 @@ module ActiveSupport
   class FileUpdateChecker
     attr_reader :paths, :last_update_at
 
+    # It accepts two parameters on initialization. The first is
+    # the *paths* and the second is *calculate*, a boolean.
+    #
+    # paths must be an array of file paths but can contain a hash as
+    # last argument. The hash must have directories as keys and the
+    # value is an array of extensions to be watched under that directory.
+    #
+    # If *calculate* is true, the latest updated at will calculated
+    # on initialization, therefore, the first call to execute_if_updated
+    # will only evaluate the block if something really changed.
+    #
+    # This method must also receive a block that will be the block called
+    # once a file changes.
+    #
+    # This particular implementation checks for added files and updated files,
+    # but not removed files. Directories lookup are compiled to a glob for
+    # performance.
     def initialize(paths, calculate=false, &block)
       @paths = paths
+      @glob  = compile_glob(@paths.extract_options!)
       @block = block
       @last_update_at = calculate ? updated_at : nil
     end
 
     def updated_at
-      # TODO: Use Enumerable check once we get rid of 1.8.7
-      all = paths.is_a?(Array) ? paths : Dir[paths]
+      all = []
+      all.concat @paths
+      all.concat Dir[@glob] if @glob
       all.map { |path| File.mtime(path) }.max
     end
 
@@ -37,5 +59,22 @@ module ActiveSupport
         false
       end
     end
+
+    private
+
+    def compile_glob(hash)
+      return if hash.empty?
+      globs = []
+      hash.each do |key, value|
+        globs << "#{key}/**/*#{compile_ext(value)}"
+      end
+      "{#{globs.join(",")}}"
+    end
+
+    def compile_ext(array)
+      array = Array.wrap(array)
+      return if array.empty?
+      ".{#{array.join(",")}}"
+    end
   end
 end

activesupport/test/file_update_checker_test.rb

@@ -4,21 +4,19 @@ require 'fileutils'
 
 MTIME_FIXTURES_PATH = File.expand_path("../fixtures", __FILE__)
 
-module FileUpdateCheckerSuite
+class FileUpdateCheckerWithEnumerableTest < Test::Unit::TestCase
   FILES = %w(1.txt 2.txt 3.txt)
 
   def setup
+    FileUtils.mkdir_p("tmp_watcher")
     FileUtils.touch(FILES)
   end
 
   def teardown
+    FileUtils.rm_rf("tmp_watcher")
     FileUtils.rm(FILES)
   end
 
-  def args
-    raise NotImplementedError
-  end
-
   def test_should_not_execute_the_block_if_no_paths_are_given
     i = 0
     checker = ActiveSupport::FileUpdateChecker.new([]){ i += 1 }
@@ -28,41 +26,51 @@ module FileUpdateCheckerSuite
 
   def test_should_invoke_the_block_on_first_call_if_it_does_not_calculate_last_updated_at_on_load
     i = 0
-    checker = ActiveSupport::FileUpdateChecker.new(args){ i += 1 }
+    checker = ActiveSupport::FileUpdateChecker.new(FILES){ i += 1 }
     checker.execute_if_updated
     assert_equal 1, i
   end
 
   def test_should_not_invoke_the_block_on_first_call_if_it_calculates_last_updated_at_on_load
     i = 0
-    checker = ActiveSupport::FileUpdateChecker.new(args, true){ i += 1 }
+    checker = ActiveSupport::FileUpdateChecker.new(FILES, true){ i += 1 }
     checker.execute_if_updated
     assert_equal 0, i
   end
 
   def test_should_not_invoke_the_block_if_no_file_has_changed
     i = 0
-    checker = ActiveSupport::FileUpdateChecker.new(args, true){ i += 1 }
+    checker = ActiveSupport::FileUpdateChecker.new(FILES, true){ i += 1 }
     5.times { assert !checker.execute_if_updated }
     assert_equal 0, i
   end
 
   def test_should_invoke_the_block_if_a_file_has_changed
     i = 0
-    checker = ActiveSupport::FileUpdateChecker.new(args, true){ i += 1 }
+    checker = ActiveSupport::FileUpdateChecker.new(FILES, true){ i += 1 }
     sleep(1)
     FileUtils.touch(FILES)
     assert checker.execute_if_updated
     assert_equal 1, i
   end
-end
 
-class FileUpdateCheckerWithEnumerableTest < Test::Unit::TestCase
-  include FileUpdateCheckerSuite
-  def args; FILES; end
-end
+  def test_should_invoke_the_block_if_a_watched_dir_changed_its_glob
+    i = 0
+    checker = ActiveSupport::FileUpdateChecker.new([{"tmp_watcher" => [:txt]}], true){ i += 1 }
+    FileUtils.cd "tmp_watcher" do
+      FileUtils.touch(FILES)
+    end
+    assert checker.execute_if_updated
+    assert_equal 1, i
+  end
 
-class FileUpdateCheckerWithStringTest < Test::Unit::TestCase
-  include FileUpdateCheckerSuite
-  def args; "{1,2,3}.txt"; end
-end
+  def test_should_not_invoke_the_block_if_a_watched_dir_changed_its_glob
+    i = 0
+    checker = ActiveSupport::FileUpdateChecker.new([{"tmp_watcher" => :rb}], true){ i += 1 }
+    FileUtils.cd "tmp_watcher" do
+      FileUtils.touch(FILES)
+    end
+    assert !checker.execute_if_updated
+    assert_equal 0, i
+  end
+end