require 'active_support/json/encoders' module ActiveSupport module JSON #:nodoc: class CircularReferenceError < StandardError #:nodoc: end # returns the literal string as its JSON encoded form. Useful for passing javascript variables into functions. # # page.call 'Element.show', ActiveSupport::JSON::Variable.new("$$(#items li)") class Variable < String #:nodoc: def to_json self end end class << self REFERENCE_STACK_VARIABLE = :json_reference_stack def encode(value) raise_on_circular_reference(value) do Encoders[value.class].call(value) end end protected def raise_on_circular_reference(value) 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