Add yajl-ruby as a JSON parsing backend

[#2666 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

activesupport/CHANGELOG

@@ -1,5 +1,10 @@
 *Rails 3.0 (pending)*
 
+* JSON backend for YAJL.  #2666 [Brian Lopez]
+
+
+*Rails 3.0.0 [beta] (February 4, 2010)*
+
 * Introduce class_attribute to declare inheritable class attributes. Writing an attribute on a subclass behaves just like overriding the superclass reader method.  Unifies and replaces most usage of cattr_accessor, class_inheritable_attribute, superclass_delegating_attribute, and extlib_inheritable_attribute.  [Jeremy Kemper, Yehuda Katz]
 
 * Time#- with a DateTime argument behaves the same as with a Time argument, i.e. returns the difference between self and arg as a Float #3476 [Geoff Buesing]

activesupport/lib/active_support/json/backends/yajl.rb

@@ -0,0 +1,40 @@
+require 'yajl-ruby' unless defined?(Yajl)
+
+module ActiveSupport
+  module JSON
+    module Backends
+      module Yajl
+        ParseError = ::Yajl::ParseError
+        extend self
+
+        # Parses a JSON string or IO and convert it into an object
+        def decode(json)
+          data = ::Yajl::Parser.new.parse(json)
+          if ActiveSupport.parse_json_times
+            convert_dates_from(data)
+          else
+            data
+          end
+        end
+
+      private
+        def convert_dates_from(data)
+          case data
+          when nil
+            nil
+          when DATE_REGEX
+            DateTime.parse(data)
+          when Array
+            data.map! { |d| convert_dates_from(d) }
+          when Hash
+            data.each do |key, value|
+              data[key] = convert_dates_from(value)
+            end
+          else
+            data
+          end
+        end
+      end
+    end
+  end
+end

activesupport/test/json/decoding_test.rb

@@ -49,6 +49,7 @@ class TestJSONDecoding < ActiveSupport::TestCase
 
   backends = %w(Yaml)
   backends << "JSONGem" if defined?(::JSON)
+  backends << "Yajl" if defined?(::Yajl)
 
   backends.each do |backend|
     TESTS.each do |json, expected|