gistfile1.rb

# Users: JSON.encode(whatever)
#
# Implementors: override dump_json(options) returning a Hash, Array, etc
#           or: override encode_json(encoder) using the encoder API to return a JSON string

require 'active_support/core_ext/array/wrap'
require 'active_support/core_ext/object/instance_variables'

module ActiveSupport
  module JSON
    # Dumps object in JSON (JavaScript Object Notation). See www.json.org for more info.
    def self.encode(value, options = nil)
      Encoder.new(options).encode(value)
    end

    class Encoder
      class CircularReferenceError < StandardError; end
      attr_reader :options

      def initialize(options)
        @options = options
        @seen = []
      end

      def encode(value)
        check_for_circular_references(value) do
          value.dump_json(options).encode_json(self)
        end
      end

      def escape(string)
        Encoding.escape(string)
      end

      private
        def check_for_circular_references(value)
          if @seen.any? { |object| object.equal?(value) }
            raise CircularReferenceError, 'object references itself'
          end
          @seen.unshift value
          yield
        ensure
          @seen.shift
        end
    end
  end
end

class Object
  def dump_json(options) self end
  def encode_json(encoder) encoder.encode(instance_values) end
end

# A string that returns itself as its JSON-encoded form.
class ActiveSupport::JSON::Variable < String
  def encode_json(encoder) self end
end

class TrueClass
  JSON_VALUE = ActiveSupport::JSON::Variable.new('true').freeze
  def dump_json(options) JSON_VALUE end
end

class FalseClass
  JSON_VALUE = ActiveSupport::JSON::Variable.new('false').freeze
  def dump_json(options) JSON_VALUE end
end

class NilClass
  JSON_VALUE = ActiveSupport::JSON::Variable.new('null').freeze
  def dump_json(options) JSON_VALUE end
end

class String
  def encode_json(encoder) encoder.escape(self) end
end

class Symbol
  def dump_json(options) to_s end
end

class Numeric
  def encode_json(encoder) to_s end
end

class Regexp
  def encode_json(encoder) inspect end
end

module Enumerable
  def encode_json(encoder) "[#{map { |v| encoder.encode(v) } * ','}]" end
end

class Hash
  def dump_json(options)
    if options
      if attrs = options[:only]
        slice(*Array.wrap(attrs))
      elsif attrs = options[:except]
        except(*Array.wrap(attrs))
      end
    else
      super
    end
  end

  def encode_json(encoder)
    "{#{map { |k,v| "#{encoder.encode(k.to_s)}:#{encoder.encode(v)}" } * ','}}"
  end
end

class Time
  def dump_json(options)
    if ActiveSupport.use_standard_json_time_format
      xmlschema
    else
      %(#{strftime("%Y/%m/%d %H:%M:%S")} #{formatted_offset(false)})
    end
  end
end

class Date
  def dump_json(options)
    if ActiveSupport.use_standard_json_time_format
      strftime("%Y-%m-%d")
    else
      strftime("%Y/%m/%d")
    end
  end
end

class DateTime
  def dump_json(options)
    if ActiveSupport.use_standard_json_time_format
      xmlschema
    else
      strftime('%Y/%m/%d %H:%M:%S %z')
    end
  end
end