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statetransition-mixin

mixin to declare state transition methods like start & stop

start stop transition example

usage

import { StateTransitionMixin, prepareActions } = from 'statetransition-mixin';

const actions = prepareActions({
start: { // declare start() and call _start() internally
  stopped: { // can be called within stopped state
    target: "running",
    during: "starting",
    timeout: 10
  }
},
stop: { // declare stop() and call _stop() internally
  running: {. // can be called when running
    target: "stopped",
    during: "stopping",
    timeout: 5
  },
  starting: { // or when starting
    target: "stopped",
    during: "stopping",
    timeout: 10
  }
}
});

class BaseClass {}

class StatefullClass extends StateTransitionMixin(BaseClass, actions, 'stopped') {

  // will be called to go from stopped to running
  async _start() {
    return new Promise(resolve => setTimeout(() => resolve(), 10));
  }
}

let myObject = new StatefullClass();

console.log(myObject.state === 'stopped' ? "is stopped" : "hmm ?")

myObject.start().then( (o) => console.log('started == ${o.state}'));
console.log('starting == ${myObject.state}');

myObject.stop().then( (o) => console.log('stopped == ${o.state}'));
console.log('stopping == ${myObject.state}');

API

Table of Contents

TRANSITION

ongoing transition

TRANSITION_PROMISE

promise of the ongoing transition

Action

Type: Object

Properties

  • name string like 'start' or 'stop'
  • transitions Object possible transitions from the current state

Transition

Type: Object

Properties

prepareActions

Compile actions and states

Parameters

Examples

prepareActions({
start:{
 stopped: {
   target: 'running',
   during: 'starting'
}},
stop: {
 running: {
   target: 'stopped',
   during: 'stopping'
 }}});

Returns Array

StateTransitionMixin

Extends a class to support state transtions.

Parameters

clazz

Generated mixin class with support of state transtions.

rejectUnlessResolvedWithin

Rejects promise when it is not resolved within given timeout.

Parameters

Returns Promise

defineActionMethods

Defines methods to perform the state transitions. States are traversed in the following way:

current -> during -> final

If the step is not in one of the transitions current states and also not already in the transitions final state a rejecting promise will be delivered from the generated function. In the 'during' state a function named '_' + (sample: '_start()') will be called first.

It is expected that this function delivers a promise.

Special handling of consequent transitions

While in a during state the former delivered promise will be delivered again. This enshures that several consequent transitions in a row will be fullfiled by the same promise. There can only be one transition in place at a given point in time.

Parameters

  • object Object target object where we define the methods

  • actionsAndStates Object object describing the state transitions

    • actionsAndStates.0
    • actionsAndStates.1

Returns void

install

With npm do:

npm install statetransition-mixin

license

BSD-2-Clause