* lib/rake: Import Rake 0.9.2

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@32217 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/rake/file_creation_task.rb

@@ -0,0 +1,24 @@
+require 'rake/file_task'
+require 'rake/early_time'
+
+module Rake
+
+  # A FileCreationTask is a file task that when used as a dependency will be
+  # needed if and only if the file has not been created.  Once created, it is
+  # not re-triggered if any of its dependencies are newer, nor does trigger
+  # any rebuilds of tasks that depend on it whenever it is updated.
+  #
+  class FileCreationTask < FileTask
+    # Is this file task needed?  Yes if it doesn't exist.
+    def needed?
+      ! File.exist?(name)
+    end
+
+    # Time stamp for file creation task.  This time stamp is earlier
+    # than any other time stamp.
+    def timestamp
+      Rake::EARLY
+    end
+  end
+
+end