Merge branch 'master' into active_model

Conflicts:
	activemodel/lib/active_model/core.rb
	activemodel/test/cases/state_machine/event_test.rb
	activemodel/test/cases/state_machine/state_transition_test.rb
	activerecord/lib/active_record/validations.rb
	activerecord/test/cases/validations/i18n_validation_test.rb
	activeresource/lib/active_resource.rb
	activeresource/test/abstract_unit.rb

18 files changed, 289 insertions, 251 deletions

diff --git a/activesupport/lib/active_support/json/backends/jsongem.rb b/activesupport/lib/active_support/json/backends/jsongem.rb
new file mode 100644
index 0000000000..649e6301d1
--- /dev/null
+++ b/activesupport/lib/active_support/json/backends/jsongem.rb
@@ -0,0 +1,41 @@
+require 'json' unless defined?(JSON)
+
+module ActiveSupport
+  module JSON
+    ParseError = ::JSON::ParserError unless const_defined?(:ParseError)
+
+    module Backends
+      module JSONGem
+        extend self
+
+        # Parses a JSON string or IO and convert it into an object
+        def decode(json)
+          if json.respond_to?(:read)
+            json = json.read
+          end
+          data = ::JSON.parse(json)
+          if ActiveSupport.parse_json_times
+            convert_dates_from(data)
+          else
+            data
+          end
+        end
+
+      private
+        def convert_dates_from(data)
+          case data
+            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
\ No newline at end of file
diff --git a/activesupport/lib/active_support/json/backends/yaml.rb b/activesupport/lib/active_support/json/backends/yaml.rb
new file mode 100644
index 0000000000..667016f45d
--- /dev/null
+++ b/activesupport/lib/active_support/json/backends/yaml.rb
@@ -0,0 +1,88 @@
+require 'active_support/core_ext/string/starts_ends_with'
+
+module ActiveSupport
+  module JSON
+    unless const_defined?(:ParseError)
+      class ParseError < StandardError
+      end
+    end
+
+    module Backends
+      module Yaml
+        extend self
+
+        # Parses a JSON string or IO and converts it into an object
+        def decode(json)
+          if json.respond_to?(:read)
+            json = json.read
+          end
+          YAML.load(convert_json_to_yaml(json))
+        rescue ArgumentError => e
+          raise ParseError, "Invalid JSON string"
+        end
+    
+        protected
+          # Ensure that ":" and "," are always followed by a space
+          def convert_json_to_yaml(json) #:nodoc:
+            require 'strscan' unless defined? ::StringScanner
+            scanner, quoting, marks, pos, times = ::StringScanner.new(json), false, [], nil, []
+            while scanner.scan_until(/(\\['"]|['":,\\]|\\.)/)
+              case char = scanner[1]
+              when '"', "'"
+                if !quoting
+                  quoting = char
+                  pos = scanner.pos
+                elsif quoting == char
+                  if json[pos..scanner.pos-2] =~ DATE_REGEX
+                    # found a date, track the exact positions of the quotes so we can remove them later.
+                    # oh, and increment them for each current mark, each one is an extra padded space that bumps
+                    # the position in the final YAML output
+                    total_marks = marks.size
+                    times << pos+total_marks << scanner.pos+total_marks
+                  end
+                  quoting = false
+                end
+              when ":",","
+                marks << scanner.pos - 1 unless quoting
+              end
+            end
+
+            if marks.empty?
+              json.gsub(/\\([\\\/]|u[[:xdigit:]]{4})/) do
+                ustr = $1
+                if ustr.start_with?('u')
+                  [ustr[1..-1].to_i(16)].pack("U")
+                elsif ustr == '\\'
+                  '\\\\'
+                else
+                  ustr
+                end
+              end
+            else
+              left_pos  = [-1].push(*marks)
+              right_pos = marks << scanner.pos + scanner.rest_size
+              output    = []
+              left_pos.each_with_index do |left, i|
+                scanner.pos = left.succ
+                output << scanner.peek(right_pos[i] - scanner.pos + 1).gsub(/\\([\\\/]|u[[:xdigit:]]{4})/) do
+                  ustr = $1
+                  if ustr.start_with?('u')
+                    [ustr[1..-1].to_i(16)].pack("U")
+                  elsif ustr == '\\'
+                    '\\\\'
+                  else
+                    ustr
+                  end
+                end
+              end
+              output = output * " "
+
+              times.each { |i| output[i-1] = ' ' }
+              output.gsub!(/\\\//, '/')
+              output
+            end
+          end
+      end
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/json/decoding.rb b/activesupport/lib/active_support/json/decoding.rb
deleted file mode 100644
index c66500aa9c..0000000000
--- a/activesupport/lib/active_support/json/decoding.rb
+++ /dev/null
@@ -1,84 +0,0 @@
-autoload :YAML, 'yaml' unless defined? YAML
-autoload :StringScanner, 'strscan' unless defined? StringScanner
-
-require 'active_support/core_ext/string/starts_ends_with'
-
-module ActiveSupport
-  module JSON
-    class ParseError < StandardError
-    end
-    
-    class << self
-      # Converts a JSON string into a Ruby object.
-      def decode(json)
-        YAML.load(convert_json_to_yaml(json))
-      rescue ArgumentError => e
-        raise ParseError, "Invalid JSON string"
-      end
-      
-      protected
-        # matches YAML-formatted dates
-        DATE_REGEX = /^(?:\d{4}-\d{2}-\d{2}|\d{4}-\d{1,2}-\d{1,2}[ \t]+\d{1,2}:\d{2}:\d{2}(\.[0-9]*)?(([ \t]*)Z|[-+]\d{2}?(:\d{2})?)?)$/
-
-        # Ensure that ":" and "," are always followed by a space
-        def convert_json_to_yaml(json) #:nodoc:
-          scanner, quoting, marks, pos, times = StringScanner.new(json), false, [], nil, []
-          while scanner.scan_until(/(\\['"]|['":,\\]|\\.)/)
-            case char = scanner[1]
-            when '"', "'"
-              if !quoting
-                quoting = char
-                pos = scanner.pos
-              elsif quoting == char
-                if json[pos..scanner.pos-2] =~ DATE_REGEX
-                  # found a date, track the exact positions of the quotes so we can remove them later.
-                  # oh, and increment them for each current mark, each one is an extra padded space that bumps
-                  # the position in the final YAML output
-                  total_marks = marks.size
-                  times << pos+total_marks << scanner.pos+total_marks
-                end
-                quoting = false
-              end
-            when ":",","
-              marks << scanner.pos - 1 unless quoting
-            end
-          end
-
-          if marks.empty?
-            json.gsub(/\\([\\\/]|u[[:xdigit:]]{4})/) do
-              ustr = $1
-              if ustr.start_with?('u')
-                [ustr[1..-1].to_i(16)].pack("U")
-              elsif ustr == '\\'
-                '\\\\'
-              else
-                ustr
-              end
-            end
-          else
-            left_pos  = [-1].push(*marks)
-            right_pos = marks << scanner.pos + scanner.rest_size
-            output    = []
-            left_pos.each_with_index do |left, i|
-              scanner.pos = left.succ
-              output << scanner.peek(right_pos[i] - scanner.pos + 1).gsub(/\\([\\\/]|u[[:xdigit:]]{4})/) do
-                ustr = $1
-                if ustr.start_with?('u')
-                  [ustr[1..-1].to_i(16)].pack("U")
-                elsif ustr == '\\'
-                  '\\\\'
-                else
-                  ustr
-                end
-              end
-            end
-            output = output * " "
-            
-            times.each { |i| output[i-1] = ' ' }
-            output.gsub!(/\\\//, '/')
-            output
-          end
-        end
-    end
-  end
-end
diff --git a/activesupport/lib/active_support/json/encoders/date.rb b/activesupport/lib/active_support/json/encoders/date.rb
index cc84de1388..9adb3c20e2 100644
--- a/activesupport/lib/active_support/json/encoders/date.rb
+++ b/activesupport/lib/active_support/json/encoders/date.rb
@@ -1,21 +1,22 @@
 class Date
-  # Returns a JSON string representing the date. If ActiveSupport.use_standard_json_time_format is set to true, the
-  # ISO 8601 format is used.
-  #
-  # ==== Examples
-  #
-  #   # With ActiveSupport.use_standard_json_time_format = true
-  #   Date.new(2005,2,1).to_json
-  #   # => "2005-02-01"
-  #
-  #   # With ActiveSupport.use_standard_json_time_format = false
-  #   Date.new(2005,2,1).to_json
-  #   # => "2005/02/01"
-  def to_json(options = nil)
-    if ActiveSupport.use_standard_json_time_format
-      %("#{strftime("%Y-%m-%d")}")
-    else
-      %("#{strftime("%Y/%m/%d")}")
+  private
+    # Returns a JSON string representing the date. If ActiveSupport.use_standard_json_time_format is set to true, the
+    # ISO 8601 format is used.
+    #
+    # ==== Examples
+    #
+    #   # With ActiveSupport.use_standard_json_time_format = true
+    #   Date.new(2005,2,1).to_json
+    #   # => "2005-02-01"
+    #
+    #   # With ActiveSupport.use_standard_json_time_format = false
+    #   Date.new(2005,2,1).to_json
+    #   # => "2005/02/01"
+    def rails_to_json(*)
+      if ActiveSupport.use_standard_json_time_format
+        %("#{strftime("%Y-%m-%d")}")
+      else
+        %("#{strftime("%Y/%m/%d")}")
+      end
     end
-  end
 end
diff --git a/activesupport/lib/active_support/json/encoders/date_time.rb b/activesupport/lib/active_support/json/encoders/date_time.rb
index 6c85824105..3a29292b24 100644
--- a/activesupport/lib/active_support/json/encoders/date_time.rb
+++ b/activesupport/lib/active_support/json/encoders/date_time.rb
@@ -1,21 +1,22 @@
 class DateTime
-  # Returns a JSON string representing the datetime. If ActiveSupport.use_standard_json_time_format is set to true, the
-  # ISO 8601 format is used.
-  #
-  # ==== Examples
-  #
-  #   # With ActiveSupport.use_standard_json_time_format = true
-  #   DateTime.civil(2005,2,1,15,15,10).to_json
-  #   # => "2005-02-01T15:15:10+00:00"
-  #
-  #   # With ActiveSupport.use_standard_json_time_format = false
-  #   DateTime.civil(2005,2,1,15,15,10).to_json
-  #   # => "2005/02/01 15:15:10 +0000"
-  def to_json(options = nil)
-    if ActiveSupport.use_standard_json_time_format
-      xmlschema.inspect
-    else
-      strftime('"%Y/%m/%d %H:%M:%S %z"')
+  private
+    # Returns a JSON string representing the datetime. If ActiveSupport.use_standard_json_time_format is set to true, the
+    # ISO 8601 format is used.
+    #
+    # ==== Examples
+    #
+    #   # With ActiveSupport.use_standard_json_time_format = true
+    #   DateTime.civil(2005,2,1,15,15,10).to_json
+    #   # => "2005-02-01T15:15:10+00:00"
+    #
+    #   # With ActiveSupport.use_standard_json_time_format = false
+    #   DateTime.civil(2005,2,1,15,15,10).to_json
+    #   # => "2005/02/01 15:15:10 +0000"
+    def rails_to_json(*)
+      if ActiveSupport.use_standard_json_time_format
+        xmlschema.inspect
+      else
+        strftime('"%Y/%m/%d %H:%M:%S %z"')
+      end
     end
-  end
 end
diff --git a/activesupport/lib/active_support/json/encoders/enumerable.rb b/activesupport/lib/active_support/json/encoders/enumerable.rb
index 881b1d62c1..898990a59c 100644
--- a/activesupport/lib/active_support/json/encoders/enumerable.rb
+++ b/activesupport/lib/active_support/json/encoders/enumerable.rb
@@ -1,12 +1,13 @@
 module Enumerable
-  # Returns a JSON string representing the enumerable. Any +options+
-  # given will be passed on to its elements. For example:
-  #
-  #   users = User.find(:all)
-  #   # => users.to_json(:only => :name)
-  #
-  # will pass the <tt>:only => :name</tt> option to each user.
-  def to_json(options = {}) #:nodoc:
-    "[#{map { |value| ActiveSupport::JSON.encode(value, options) } * ', '}]"
-  end
+  private
+    # Returns a JSON string representing the enumerable. Any +options+
+    # given will be passed on to its elements. For example:
+    #
+    #   users = User.find(:all)
+    #   # => users.to_json(:only => :name)
+    #
+    # will pass the <tt>:only => :name</tt> option to each user.
+    def rails_to_json(options = nil, *args) #:nodoc:
+      "[#{map { |value| ActiveSupport::JSON.encode(value, options, *args) } * ','}]"
+    end
 end
diff --git a/activesupport/lib/active_support/json/encoders/false_class.rb b/activesupport/lib/active_support/json/encoders/false_class.rb
index bf0844334b..eb975fe542 100644
--- a/activesupport/lib/active_support/json/encoders/false_class.rb
+++ b/activesupport/lib/active_support/json/encoders/false_class.rb
@@ -1,5 +1,6 @@
 class FalseClass
-  def to_json(options = nil) #:nodoc:
-    'false'
-  end
+  private
+    def rails_to_json(*)
+      'false'
+    end
 end
diff --git a/activesupport/lib/active_support/json/encoders/hash.rb b/activesupport/lib/active_support/json/encoders/hash.rb
index d87b880743..4771484843 100644
--- a/activesupport/lib/active_support/json/encoders/hash.rb
+++ b/activesupport/lib/active_support/json/encoders/hash.rb
@@ -1,48 +1,51 @@
 require 'active_support/core_ext/array/wrap'
 
 class Hash
-  # Returns a JSON string representing the hash.
-  #
-  # Without any +options+, the returned JSON string will include all
-  # the hash keys. For example:
-  #
-  #   { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json
-  #   # => {"name": "Konata Izumi", "1": 2, "age": 16}
-  #
-  # The keys in the JSON string are unordered due to the nature of hashes.
-  #
-  # The <tt>:only</tt> and <tt>:except</tt> options can be used to limit the
-  # attributes included, and will accept 1 or more hash keys to include/exclude.
-  #
-  #   { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json(:only => [:name, 'age'])
-  #   # => {"name": "Konata Izumi", "age": 16}
-  #
-  #   { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json(:except => 1)
-  #   # => {"name": "Konata Izumi", "age": 16}
-  #
-  # The +options+ also filter down to any hash values. This is particularly
-  # useful for converting hashes containing ActiveRecord objects or any object
-  # that responds to options in their <tt>to_json</tt> method. For example:
-  #
-  #   users = User.find(:all)
-  #   { :users => users, :count => users.size }.to_json(:include => :posts)
-  #
-  # would pass the <tt>:include => :posts</tt> option to <tt>users</tt>,
-  # allowing the posts association in the User model to be converted to JSON
-  # as well.
-  def to_json(options = {}) #:nodoc:
-    hash_keys = self.keys
+  private
+    # Returns a JSON string representing the hash.
+    #
+    # Without any +options+, the returned JSON string will include all
+    # the hash keys. For example:
+    #
+    #   { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json
+    #   # => {"name": "Konata Izumi", "1": 2, "age": 16}
+    #
+    # The keys in the JSON string are unordered due to the nature of hashes.
+    #
+    # The <tt>:only</tt> and <tt>:except</tt> options can be used to limit the
+    # attributes included, and will accept 1 or more hash keys to include/exclude.
+    #
+    #   { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json(:only => [:name, 'age'])
+    #   # => {"name": "Konata Izumi", "age": 16}
+    #
+    #   { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json(:except => 1)
+    #   # => {"name": "Konata Izumi", "age": 16}
+    #
+    # The +options+ also filter down to any hash values. This is particularly
+    # useful for converting hashes containing ActiveRecord objects or any object
+    # that responds to options in their <tt>to_json</tt> method. For example:
+    #
+    #   users = User.find(:all)
+    #   { :users => users, :count => users.size }.to_json(:include => :posts)
+    #
+    # would pass the <tt>:include => :posts</tt> option to <tt>users</tt>,
+    # allowing the posts association in the User model to be converted to JSON
+    # as well.
+    def rails_to_json(options = nil, *args) #:nodoc:
+      hash_keys = self.keys
 
-    if except = options[:except]
-      hash_keys = hash_keys - Array.wrap(except)
-    elsif only = options[:only]
-      hash_keys = hash_keys & Array.wrap(only)
-    end
+      if options
+        if except = options[:except]
+          hash_keys = hash_keys - Array.wrap(except)
+        elsif only = options[:only]
+          hash_keys = hash_keys & Array.wrap(only)
+        end
+      end
 
-    result = '{'
-    result << hash_keys.map do |key|
-      "#{ActiveSupport::JSON.encode(key.to_s)}: #{ActiveSupport::JSON.encode(self[key], options)}"
-    end * ', '
-    result << '}'
-  end
+      result = '{'
+      result << hash_keys.map do |key|
+        "#{ActiveSupport::JSON.encode(key.to_s)}:#{ActiveSupport::JSON.encode(self[key], options, *args)}"
+      end * ','
+      result << '}'
+    end
 end
diff --git a/activesupport/lib/active_support/json/encoders/nil_class.rb b/activesupport/lib/active_support/json/encoders/nil_class.rb
index 4763471ac4..8c51dba384 100644
--- a/activesupport/lib/active_support/json/encoders/nil_class.rb
+++ b/activesupport/lib/active_support/json/encoders/nil_class.rb
@@ -1,5 +1,6 @@
 class NilClass
-  def to_json(options = nil) #:nodoc:
-    'null'
-  end
+  private
+    def rails_to_json(*)
+      'null'
+    end
 end
diff --git a/activesupport/lib/active_support/json/encoders/numeric.rb b/activesupport/lib/active_support/json/encoders/numeric.rb
index 38713fb369..c7cd0df1d7 100644
--- a/activesupport/lib/active_support/json/encoders/numeric.rb
+++ b/activesupport/lib/active_support/json/encoders/numeric.rb
@@ -1,5 +1,6 @@
 class Numeric
-  def to_json(options = nil) #:nodoc:
-    to_s
-  end
+  private
+    def rails_to_json(*)
+      to_s
+    end
 end
diff --git a/activesupport/lib/active_support/json/encoders/object.rb b/activesupport/lib/active_support/json/encoders/object.rb
index 0475967aee..9cc12d91ac 100644
--- a/activesupport/lib/active_support/json/encoders/object.rb
+++ b/activesupport/lib/active_support/json/encoders/object.rb
@@ -2,7 +2,12 @@ require 'active_support/core_ext/object/instance_variables'
 
 class Object
   # Dumps object in JSON (JavaScript Object Notation). See www.json.org for more info.
-  def to_json(options = {})
-    ActiveSupport::JSON.encode(instance_values, options)
+  def to_json(options = nil)
+    ActiveSupport::JSON.encode(self, options)
   end
+
+  private
+    def rails_to_json(*args)
+      ActiveSupport::JSON.encode(instance_values, *args)
+    end
 end
diff --git a/activesupport/lib/active_support/json/encoders/regexp.rb b/activesupport/lib/active_support/json/encoders/regexp.rb
index b6116b70b5..ee42db4d02 100644
--- a/activesupport/lib/active_support/json/encoders/regexp.rb
+++ b/activesupport/lib/active_support/json/encoders/regexp.rb
@@ -1,5 +1,6 @@
 class Regexp
-  def to_json(options = nil) #:nodoc:
-    inspect
-  end
+  private
+    def rails_to_json(*)
+      inspect
+    end
 end
diff --git a/activesupport/lib/active_support/json/encoders/string.rb b/activesupport/lib/active_support/json/encoders/string.rb
index 5ef797955a..4a6b21c1c0 100644
--- a/activesupport/lib/active_support/json/encoders/string.rb
+++ b/activesupport/lib/active_support/json/encoders/string.rb
@@ -1,36 +1,6 @@
-module ActiveSupport
-  module JSON
-    module Encoding
-      mattr_accessor :escape_regex
-
-      ESCAPED_CHARS = {
-        "\010" =>  '\b',
-        "\f"   =>  '\f',
-        "\n"   =>  '\n',
-        "\r"   =>  '\r',
-        "\t"   =>  '\t',
-        '"'    =>  '\"',
-        '\\'   =>  '\\\\',
-        '>'    =>  '\u003E',
-        '<'    =>  '\u003C',
-        '&'    =>  '\u0026'
-      }
-    end
-  end
-end
-
-ActiveSupport.escape_html_entities_in_json = true
-
 class String
-  def to_json(options = nil) #:nodoc:
-    json = '"' + gsub(ActiveSupport::JSON::Encoding.escape_regex) { |s|
-      ActiveSupport::JSON::Encoding::ESCAPED_CHARS[s]
-    }
-    json.force_encoding('ascii-8bit') if respond_to?(:force_encoding)
-    json.gsub(/([\xC0-\xDF][\x80-\xBF]|
-             [\xE0-\xEF][\x80-\xBF]{2}|
-             [\xF0-\xF7][\x80-\xBF]{3})+/nx) { |s|
-      s.unpack("U*").pack("n*").unpack("H*")[0].gsub(/.{4}/, '\\\\u\&')
-    } + '"'
-  end
+  private
+    def rails_to_json(*)
+      ActiveSupport::JSON::Encoding.escape(self)
+    end
 end
diff --git a/activesupport/lib/active_support/json/encoders/symbol.rb b/activesupport/lib/active_support/json/encoders/symbol.rb
index 485112f97c..d575350a4e 100644
--- a/activesupport/lib/active_support/json/encoders/symbol.rb
+++ b/activesupport/lib/active_support/json/encoders/symbol.rb
@@ -1,5 +1,6 @@
 class Symbol
-  def to_json(options = {}) #:nodoc:
-    ActiveSupport::JSON.encode(to_s, options)
-  end
+  private
+    def rails_to_json(*args)
+      ActiveSupport::JSON.encode(to_s, *args)
+    end
 end
diff --git a/activesupport/lib/active_support/json/encoders/time.rb b/activesupport/lib/active_support/json/encoders/time.rb
index f45a0059e8..d434b9aace 100644
--- a/activesupport/lib/active_support/json/encoders/time.rb
+++ b/activesupport/lib/active_support/json/encoders/time.rb
@@ -1,21 +1,24 @@
+require 'active_support/core_ext/time/conversions'
+
 class Time
-  # Returns a JSON string representing the time. If ActiveSupport.use_standard_json_time_format is set to true, the
-  # ISO 8601 format is used.
-  #
-  # ==== Examples
-  #
-  #   # With ActiveSupport.use_standard_json_time_format = true
-  #   Time.utc(2005,2,1,15,15,10).to_json
-  #   # => "2005-02-01T15:15:10Z"
-  #
-  #   # With ActiveSupport.use_standard_json_time_format = false
-  #   Time.utc(2005,2,1,15,15,10).to_json
-  #   # => "2005/02/01 15:15:10 +0000"
-  def to_json(options = nil)
-    if ActiveSupport.use_standard_json_time_format
-      xmlschema.inspect
-    else
-      %("#{strftime("%Y/%m/%d %H:%M:%S")} #{formatted_offset(false)}")
+  private
+    # Returns a JSON string representing the time. If ActiveSupport.use_standard_json_time_format is set to true, the
+    # ISO 8601 format is used.
+    #
+    # ==== Examples
+    #
+    #   # With ActiveSupport.use_standard_json_time_format = true
+    #   Time.utc(2005,2,1,15,15,10).to_json
+    #   # => "2005-02-01T15:15:10Z"
+    #
+    #   # With ActiveSupport.use_standard_json_time_format = false
+    #   Time.utc(2005,2,1,15,15,10).to_json
+    #   # => "2005/02/01 15:15:10 +0000"
+    def rails_to_json(*)
+      if ActiveSupport.use_standard_json_time_format
+        xmlschema.inspect
+      else
+        %("#{strftime("%Y/%m/%d %H:%M:%S")} #{formatted_offset(false)}")
+      end
     end
-  end
 end
diff --git a/activesupport/lib/active_support/json/encoders/true_class.rb b/activesupport/lib/active_support/json/encoders/true_class.rb
index 037d812b3f..bc25a6db78 100644
--- a/activesupport/lib/active_support/json/encoders/true_class.rb
+++ b/activesupport/lib/active_support/json/encoders/true_class.rb
@@ -1,5 +1,6 @@
 class TrueClass
-  def to_json(options = nil) #:nodoc:
-    'true'
-  end
+  private
+    def rails_to_json(*)
+      'true'
+    end
 end
diff --git a/activesupport/lib/active_support/json/encoding.rb b/activesupport/lib/active_support/json/encoding.rb
index aaaa3cdfd2..5fefe5b88b 100644
--- a/activesupport/lib/active_support/json/encoding.rb
+++ b/activesupport/lib/active_support/json/encoding.rb
@@ -4,11 +4,13 @@ module ActiveSupport
     end
 
     # Converts a Ruby object into a JSON string.
-    def self.encode(value, options = {})
-      seen = (options[:seen] ||= [])
-      raise CircularReferenceError, 'object references itself' if seen.include?(value)
+    def self.encode(value, options = nil, seen = nil)
+      seen ||= []
+      if seen.any? { |object| object.equal?(value) }
+        raise CircularReferenceError, 'object references itself'
+      end
       seen << value
-      value.send(:to_json, options)
+      value.__send__(:rails_to_json, options, seen)
     ensure
       seen.pop
     end
diff --git a/activesupport/lib/active_support/json/variable.rb b/activesupport/lib/active_support/json/variable.rb
index 7fd23b0a9e..daa7449b71 100644
--- a/activesupport/lib/active_support/json/variable.rb
+++ b/activesupport/lib/active_support/json/variable.rb
@@ -2,9 +2,10 @@ module ActiveSupport
   module JSON
     # A string that returns itself as its JSON-encoded form.
     class Variable < String
-      def to_json(options=nil)
-        self
-      end
+      private
+        def rails_to_json(*)
+          self
+        end
     end
   end
 end