Pastafari

Pastafari is a library for building simple finite state machines in Ruby.

Installation

Add this line to your application's Gemfile:

gem 'pastafari'

And then execute:

$ bundle

Or install it yourself as:

$ gem install pastafari

Usage

# Pastafari offers a simple DSL for defining state machines:
fsm = Pastafari::FSM.build do
  # Define when the state transition functions run:
  transition :after # Valid values are :before & :after (default)

  initial_state :first_state
  # If the initial state isn't called, the first state defined is the initial.

  state :first_state do
    # You must define a processing function:
    process { |i| puts i }
    # Pastafari raises an error if #process isn't called.

    # State change is defined with transition functions:
    transition_to(:second_state).when { |i| i == 1 }
    # The transition function must return a boolean value. If it returns `true`,
    # the FSM will transition to the new state.

    # A state can define more than one transition function:
    transition_to(:third_state).when { |i| i == 2 }

    # If a transition references a state that isn't defined, Pastafari will
    # raise an error.    
  end

  state :second_state do
    process { |i| puts i / 2 }

    transition_to(:third_state).when { |i| i == 2 }
  end

  # A state without any transition functions is final - the FSM will remain
  # in that state once it reaches it.
  state :third_state do
    process { |i| puts i / 3 }
  end
end

# Process input by calling #run, passing in an array, or a value that can be
# converted into an Array.
fsm.run([1, 2, 3]) # => should print 1, 1, 1

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/pastafari. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.