state_machina 1.0.3

An incredibly simple state machine library for Flutter and other Dart applications.

State Machina [steyt mah-kuh-nuh] 🤖

A super simple, zero dependency, tiny state machine for Flutter and other Dart apps.

Usage

import 'package:state_machina/state_machina.dart';

// Define your states in a handy enum for easy reference:
enum States { enteringEmail, sendingEmail, success }

// Create a state machine like so:
var state = StateMachine({
  States.enteringEmail: [States.sendingEmail],
  States.sendingEmail: [States.success],
  States.success: [],
});

Now you can read the current state:

// in some Flutter widget
if (state.current == States.success) return SuccessMessage()

And change the state:

// somewhere in your Flutter app...
RaisedButton(
  onPressed: () async {
    try {
      setState(() {
        state.changeTo(States.sendingEmail);
      });

      await _sendEmail();

      setState(() {
        state.changeTo(States.success);
      });
    } catch (e) {
      ...
    }
  },
  child: const Text('Submit')
)

Additional Details

• You may pass an optional initialState string as the second argument (positional). If not, the initial state defaults to the key of the first entry in the state map.
• Runtime exceptions will be thrown if you pass in an invalid state map (unreachable states, next states that don't exist) or an invalid initial state, or if you attempt to change to a state that doesn't exist or isn't a valid next state for the current state.
• You can also define your states using a class, if desired:

class States {
  static final String enteringEmail = 'enteringEmail';
  static final String sendingEmail = 'sendingEmail';
  static final String success = 'success';
}

The type of individual states can be anything: String, int, object. You simply have to ensure that your state map is sound (you'll get helpful error messages if it isn't).

API

StateMachine Function(Map<String, List<String>> stateMap, [String initialState])