statemachine's Introduction

Finite state machine

An elegant finite state machine (DFA) written in Kotlin. Base code was in this answer I added strong-typing support and maybe other stuff.

Add to your dependencies

Add it in your root build.gradle at the end of repositories:

allprojects {
	repositories {
		maven { url 'https://jitpack.io' }
	}
}

Step 2. Add the dependency

dependencies {
    compile 'com.github.shakram02:Kt-FSM:v0.0.4'
    // implementation 'com.github.shakram02:Kt-FSM:v0.0.4'	// For android
}

Example

The following code represents this FSM

Code

import fsm.BaseEvent
import fsm.BaseState
import fsm.StateMachine

// Inherit your custom events and states from provided base classes
class GoUp : BaseEvent()

class Initial : BaseState()
class Repeat : BaseState()

fun main(args: Array<String>) {

    val m = StateMachine.buildStateMachine(Initial()) {
        state(Initial()) {
            // Code written outside action{} will run as Kotlin's init{}
            println("Initializing")
            // Code on state processing
            action {
                println("Entered [${it.name.javaClass.simpleName}]")
            }
            edge(GoUp(), Repeat()) {
                // Code of transition
                action {
                    println("Going to Repeat state")
                }
            }
        }
        state(Repeat()) {
            action {
                println("Entered [${it.name.javaClass.simpleName}]")
            }

            // Multiple actions
            action {
                println("Will get bored!")
            }

            edge(GoUp(), Repeat()) {
                action {
                    println("Repeating")
                }
            }
        }
    }

    m.initialize()
    m.acceptEvent(GoUp())
    m.acceptEvent(GoUp())
    m.acceptEvent(GoUp())
}

Output

Initializing
Entered [Initial]
Going to Repeat state
Entered [Repeat]
Will get bored!
Repeating
Entered [Repeat]
Will get bored!
Repeating
Entered [Repeat]
Will get bored!

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