Add optional fallback return value parameter

lib/psych.rb

@@ -228,6 +228,8 @@ module Psych
   # The version of libyaml Psych is using
   LIBYAML_VERSION = Psych.libyaml_version.join '.'
 
+  FALLBACK        = Struct.new :to_ruby # :nodoc:
+
   ###
   # Load +yaml+ in to a Ruby data structure.  If multiple documents are
   # provided, the object contained in the first document will be returned.
@@ -247,8 +249,8 @@ module Psych
   #     ex.file    # => 'file.txt'
   #     ex.message # => "(file.txt): found character that cannot start any token"
   #   end
-  def self.load yaml, filename = nil
-    result = parse(yaml, filename)
+  def self.load yaml, filename = nil, fallback = false
+    result = parse(yaml, filename, fallback)
     result ? result.to_ruby : result
   end
 
@@ -320,11 +322,11 @@ def self.safe_load yaml, whitelist_classes = [], whitelist_symbols = [], aliases
   #   end
   #
   # See Psych::Nodes for more information about YAML AST.
-  def self.parse yaml, filename = nil
+  def self.parse yaml, filename = nil, fallback = false
     parse_stream(yaml, filename) do |node|
       return node
     end
-    false
+    fallback
   end
 
   ###
@@ -465,9 +467,12 @@ def self.load_stream yaml, filename = nil
 
   ###
   # Load the document contained in +filename+.  Returns the yaml contained in
-  # +filename+ as a Ruby object
-  def self.load_file filename
-    File.open(filename, 'r:bom|utf-8') { |f| self.load f, filename }
+  # +filename+ as a Ruby object, or if the file is empty, it returns
+  # the specified default return value, which defaults to an empty Hash 
+  def self.load_file filename, fallback = false
+    File.open(filename, 'r:bom|utf-8') { |f|
+      self.load f, filename, FALLBACK.new(fallback)
+    }
   end
 
   # :stopdoc:

test/psych/test_psych.rb

@@ -143,6 +143,11 @@ def test_load_file
     }
   end
 
+  def test_load_file_with_fallback
+    t = Tempfile.create(['empty', 'yml'])
+    assert_equal Hash.new, Psych.load_file(t.path, Hash.new)
+  end
+
   def test_parse_file
     Tempfile.create(['yikes', 'yml']) {|t|
       t.binmode