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<?php |
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namespace Thinktomorrow\Chief\States\State; |
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abstract class StateMachine |
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{ |
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/** |
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* States and transitions should be set on the specific state Machine. |
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* |
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* @var array |
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*/ |
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protected $states = []; |
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protected $transitions = []; |
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/** |
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* @var StatefulContract |
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*/ |
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protected $statefulContract; |
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public function __construct(StatefulContract $statefulContract) |
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{ |
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// TODO: add event dispatcher cause here we want to add loads of events no? |
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// NO! WE SHOULD BETTER TO THIS ON THE AGGREGATE |
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$this->statefulContract = $statefulContract; |
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$this->validateTransitions(); |
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} |
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public function apply($transition) |
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{ |
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// Check valid transition request |
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if (!array_key_exists($transition, $this->transitions)) { |
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throw StateException::invalidTransitionKey($transition, $this); |
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} |
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if (!in_array($this->statefulContract->state(), $this->transitions[$transition]['from'])) { |
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throw StateException::invalidTransition($transition, $this->statefulContract->state(), $this); |
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} |
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$state = $this->transitions[$transition]['to']; |
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$this->statefulContract->changeState($state); |
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} |
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/** |
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* assert the integrity of the new state. |
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* |
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* @param StatefulContract $statefulContract |
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* @param $state |
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* |
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* @throws StateException |
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*/ |
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public static function assertNewState(StatefulContract $statefulContract, $state) |
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{ |
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$machine = new static($statefulContract); |
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if (!$machine->canTransitionTo($state)) { |
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throw StateException::invalidState($state, $statefulContract->state(), $machine); |
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} |
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} |
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/** |
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* Verify the new state is valid. |
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* |
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* @param $state |
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* |
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* @return bool |
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*/ |
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public function canTransitionTo($state) |
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{ |
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if (!in_array($state, $this->states)) { |
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return false; |
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} |
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foreach ($this->transitions as $transition) { |
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if (!in_array($this->statefulContract->state(), $transition['from'])) { |
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continue; |
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} |
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if ($transition['to'] == $state) { |
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return true; |
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} |
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} |
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return false; |
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} |
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public function allowedTransitions(): array |
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{ |
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$transitions = []; |
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foreach($this->transitions as $transitionKey => $transition){ |
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if (false !== array_search($this->statefulContract->state(), $transition['from'])) { |
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$transitions[] = $transitionKey; |
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} |
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} |
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return $transitions; |
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} |
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private function validateTransitions() |
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{ |
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foreach ($this->transitions as $transitionKey => $transition) { |
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if (!isset($transition['from']) || !isset($transition['to']) || !is_array($transition['from'])) { |
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throw StateException::malformedTransition($transitionKey, $this); |
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} |
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foreach ($transition['from'] as $fromState) { |
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if (!in_array($fromState, $this->states)) { |
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throw StateException::invalidTransitionState($transitionKey, $fromState, $this); |
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} |
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} |
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if (!in_array($transition['to'], $this->states)) { |
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throw StateException::invalidTransitionState($transitionKey, $transition['to'], $this); |
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} |
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} |
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} |
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} |
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thinktomorrow /
chief
