brainy

Simple state machine library for Golang, that aims to be compliant with SCXML specification, with an API similar to the amazing XState library.

Quick start

go get -u github.com/Devessier/brainy

package main

import (
	"fmt"

	"github.com/Devessier/brainy"
)

const (
	OnState  brainy.StateType = "on"
	OffState brainy.StateType = "off"

	ToggleEvent brainy.EventType = "TOGGLE"
)

func main() {
	lightSwitchStateMachine, err := brainy.NewMachine(brainy.StateNode{
		Initial: OffState,

		States: brainy.StateNodes{
			OnState: &brainy.StateNode{
				OnEntry: brainy.Actions{
					brainy.ActionFn(
						func(c brainy.Context, e brainy.Event) error {
							fmt.Println("Reached `on` state")

							return nil
						},
					),
				},

				On: brainy.Events{
					ToggleEvent: brainy.Transition{
						Target: OffState,
						Actions: brainy.Actions{
							brainy.ActionFn(
								func(c brainy.Context, e brainy.Event) error {
									fmt.Println("Go to `off` state")

									return nil
								},
							),
						},
					},
				},
			},

			OffState: &brainy.StateNode{
				OnEntry: brainy.Actions{
					brainy.ActionFn(
						func(c brainy.Context, e brainy.Event) error {
							fmt.Println("Reached `off` state")

							return nil
						},
					),
				},

				On: brainy.Events{
					ToggleEvent: brainy.Transition{
						Target: OnState,
						Actions: brainy.Actions{
							brainy.ActionFn(
								func(c brainy.Context, e brainy.Event) error {
									fmt.Println("Go to `on` state")

									return nil
								},
							),
						},
					},
				},
			},
		},
	})
	if err != nil {
		fmt.Printf("invalid state machine declaration: %s\n", err)
		return
	}

	currentState := lightSwitchStateMachine.Current()
	fmt.Printf("The current state of the state machine is: %s\n", currentState.Value()) // (machine).off
	fmt.Printf("The light switch is off: %v\n", currentState.Matches(OffState))         // true

	lightSwitchStateMachine.Send(ToggleEvent)

	stateAfterFirstToggle := lightSwitchStateMachine.Current()
	fmt.Printf("The state of the state machine after the first toogle is: %s\n", stateAfterFirstToggle.Value()) // (machine).on
	fmt.Printf("The light switch is on: %v\n", stateAfterFirstToggle.Matches(OnState))                          // true

	lightSwitchStateMachine.Send(ToggleEvent)

	stateAfterSecondToggle := lightSwitchStateMachine.Current()
	fmt.Printf("The state of the state machine after the second toogle is: %s\n", stateAfterSecondToggle.Value()) // (machine).off
	fmt.Printf("Is the light switch on? %v\n", stateAfterSecondToggle.Matches(OnState))                           // false

}

Credits

The original implementation of this library was based on this very great article: https://venilnoronha.io/a-simple-state-machine-framework-in-go.