if_lambda support for declarative authorization

if_lambda

module Authorization                                                                                                                                                                                                               
  module Reader
    class AuthorizationRulesReader
      def if_lambda (lambda_fn)
        raise DSLError, "if_lambda only in has_permission blocks" if @current_rule.nil?
        @current_rule.append_attribute AttributeLambda.new(lambda_fn)
      end
    end
  end

  class AttributeLambda
    # lambda_fn of form
    # ->() { true }
    def initialize (lambda_fn)
      @lambda_fn = lambda_fn
    end

    def initialize_copy (from)
      @lambda_fn = @lambda_fn.clone
    end

    def validate? (attr_validator, object = nil, hash = nil)
      object ||= attr_validator.object

      @lambda_fn.parameters.empty? ? @lambda_fn.call : @lambda_fn.call(object)
    end

    # resolves all the values in condition_hash
    def obligation (attr_validator, hash = nil)
      {}
    end

    def to_long_s (hash = nil)
      "if_lambda #{to_long_s(@lambda_fn).inspect}"
    end
  end
end