version: 0.1.0
This package contains a simple/lightweight library for implementing state machines in Scala. The library allows the client to use their own state, input types and transition functions.
My main goals are:
- to provide a library that is easy to use, it has a simple API.
- to provide a library with zero dependencies.
Currently only one implementation of the StateMachine interface exists. I am open to suggestions for other types of state machines:
StateMachine.WithFunctionTransitions[State, Input]: allows clients to specify transitions of typePartialFunction[(State, Input), State]. If the transition is not defined for a (State, Input) then the StateMachine will remain in its current state.
resolvers += Resolver.sonatypeRepo("public")
...
libraryDependencies += "org.driangle" %% "simple-state-machine" % "0.1.0"import org.driangle.sm.StateMachine
val sm = StateMachine.WithFunctionTransitions[String, String]()
.initialState("Inactive")
.transition({
case ("Inactive", "Begin") => "Active"
case ("Inactive", "Exit") => "Exit"
case ("Active", "End") => "Inactive"
case ("Active", "Pause") => "Paused"
case ("Paused", "Resume") => "Active"
case ("Paused", "End") => "Inactive"
})
.build()// currentState: gets the current state of the StateMachine
val state = sm.currentState
// consume(input) : causes the StateMachine to consume an input and advance to the next state according to its transition function
val nextState = sm.consume("Begin")
// peek(input): allows a client to peek at the next state if the StateMachine were to consume the given input.
val potentialNextState = sm.peek("Pause")
// reset() : allows client to reset StateMachine back to its initial state
val initialState = sm.reset()
// set(state) : allows client to forcefully change the state of teh StateMachine
sm.set("CustomState")import org.driangle.sm.StateMachine
case class UIState(clicks : Seq[Point])
sealed trait UserEvent
case class MousePressed(mouse : Point) extends UserEvent
case class KeyPressed(key : Char) extends UserEvent
val sm = StateMachine.WithFunctionTransitions[UIState, UserEvent]()
.initialState(UIState())
.transition({
// when Mouse is pressed, then add location to list of clicks
case (state, MousePressed(mouse)) => state.copy(clicks = state.clicks :+ mouse)
// when key 'c' is pressed then clear the mouse clicks
case (state, KeyPressed(key)) if key == 'c' => state.copy(clicks = List.empty)
})
.build() This software is licensed under the Apache 2 license, quoted below.
Copyright 2019 Germán Greiner
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
