README

State Machines in PHP made safe and easy.

Installation

Using Composer:

$ composer require halfowl/statemachine

Example

Imagine an application that holds the state of an article. It has the following states:

Draft
Awaiting Copy Edit
Published

A new article starts in "Draft", gets progressed to "Awaiting Copy Edit", and subsequently "Published". An article in "Awaiting Copy Edit" can go back to being a "Draft".

With this library, you can model the above as:

<?php

use Halfowl\StateMachine\{State, StateMachine, StateTransition};

$draft = new State("DRAFT");
$awaitingCopy = new State("AWAITING_COPY_EDIT");
$published = new State("PUBLISHED");

// StateTransitions define legal state transitions for the StateMachine.
// The second parameter of the constructor takes in an array of States
// that the first State can transition to.
$fromDraft = new StateTransition($draft, [$awaitingCopy]);  // draft->awaiting copy
$fromAwaitingCopy = new StateTransition($awaitingCopy, [$draft, $published]);  // awaiting copy->draft/published

// Put that together into a StateMachine:
$sm = new StateMachine(
    transitions: [
        $fromDraft,
        $fromAwaitingCopy,
    ],
    starting: $draft,
);

$sm->current();                  // => DRAFT
$sm->transition($awaitingCopy);  // => AWAITING_COPY_EDIT
$sm->transition($published);     // => PUBLISHED