aasm/lib/aasm/transition.rb

module AASM
  class Transition
    attr_reader :from, :to, :opts
    alias_method :options, :opts

    def initialize(opts)
      @from, @to, @guard, @on_transition = opts[:from], opts[:to], opts[:guard], opts[:on_transition]
      @opts = opts
    end

    # TODO: should be named allowed? or similar
    def perform(obj, *args)
      case @guard
        when Symbol, String
          obj.send(@guard, *args)
        when Proc
          @guard.call(obj, *args)
        else
          true
      end
    end

    def execute(obj, *args)
      @on_transition.is_a?(Array) ?
              @on_transition.each {|ot| _execute(obj, ot, *args)} :
              _execute(obj, @on_transition, *args)
    end

    def ==(obj)
      @from == obj.from && @to == obj.to
    end

    def from?(value)
      @from == value
    end

    private

    def _execute(obj, on_transition, *args)
      case on_transition
      when Proc
        on_transition.arity == 0 ? on_transition.call : on_transition.call(obj, *args)
      when Symbol, String
        obj.send(:method, on_transition.to_sym).arity == 0 ? obj.send(on_transition) : obj.send(on_transition, *args)
      end
    end

  end
end # AASM