1 files changed, 45 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/json/encoding.rb b/activesupport/lib/active_support/json/encoding.rb
new file mode 100644
index 0000000000..babb65a924
--- /dev/null
+++ b/activesupport/lib/active_support/json/encoding.rb
@@ -0,0 +1,45 @@
+require 'active_support/json/variable'
+
+require 'active_support/json/encoders/object' # Require this file explicitly for rdoc
+Dir[File.dirname(__FILE__) + '/encoders/**/*.rb'].each { |file| require file[0..-4] }
+
+module ActiveSupport
+  module JSON
+    # When +true+, Hash#to_json will omit quoting string or symbol keys
+    # if the keys are valid JavaScript identifiers.  Note that this is
+    # technically improper JSON (all object keys must be quoted), so if
+    # you need strict JSON compliance, set this option to +false+.
+    mattr_accessor :unquote_hash_key_identifiers
+    @@unquote_hash_key_identifiers = true
+
+    class CircularReferenceError < StandardError
+    end
+
+    class << self
+      REFERENCE_STACK_VARIABLE = :json_reference_stack #:nodoc:
+
+      # Converts a Ruby object into a JSON string.
+      def encode(value)
+        raise_on_circular_reference(value) do
+          value.send(:to_json)
+        end
+      end
+
+      def can_unquote_identifier?(key) #:nodoc:
+        unquote_hash_key_identifiers && 
+          ActiveSupport::JSON.valid_identifier?(key)
+      end
+
+      protected
+        def raise_on_circular_reference(value) #:nodoc:
+          stack = Thread.current[REFERENCE_STACK_VARIABLE] ||= []
+          raise CircularReferenceError, 'object references itself' if
+            stack.include? value
+          stack << value
+          yield
+        ensure
+          stack.pop
+        end
+    end
+  end
+end