Implement state machine concept (#3)

* Several fixes and implement state machine concept * Update readme and composer * Fix readme link on gfm
uuf6429 · Jul 24, 2021 · f227ab2 · f227ab2
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diff --git a/.gitattributes b/.gitattributes
@@ -0,0 +1,5 @@
+/.gitattributes         export-ignore
+/.github                export-ignore
+/.gitignore             export-ignore
+/phpunit.xml.dist       export-ignore
+/tests                  export-ignore
diff --git a/README.md b/README.md
@@ -1,14 +1,19 @@
-# State Engine (PHP)
+# State Engine / Machine (PHP)
 
 [![CI](https://github.com/uuf6429/state-engine-php/actions/workflows/ci.yml/badge.svg)](https://github.com/uuf6429/state-engine-php/actions/workflows/ci.yml)
 [![Minimum PHP Version](https://img.shields.io/badge/php-%5E7.4%20%7C%20%5E8-8892BF.svg)](https://php.net/)
 [![License](http://poser.pugx.org/uuf6429/state-engine/license)](https://packagist.org/packages/uuf6429/state-engine)
 [![Latest Stable Version](http://poser.pugx.org/uuf6429/state-engine/v)](https://packagist.org/packages/uuf6429/state-engine)
 [![Latest Unstable Version](http://poser.pugx.org/uuf6429/state-engine/v/unstable)](https://packagist.org/packages/uuf6429/state-engine)
 
-This library provides some interfaces and a basic implementation of a State Engine.
+This library provides some interfaces and a basic implementation of a State Engine or State Machine.
 
 **Highlights:**
+- Dual functionality:
+  1. Either as a basic state engine; switching to a desired state as long the transition is defined)
+     ([see "JiraIssueTest"](#jiraissuetest-state-engine))
+  2. Or a more sophisticated state machine; same as above but matching data for any state
+     ([see "TurnstileTest"](#turnstiletest-state-machine))
 - Highly composable - everything can be replaced as desired
 - [PSR-14](http://www.php-fig.org/psr/psr-14/) (Event Dispatcher) compatible
 - Fluent builder interface ([see "From Scratch"](#from-scratch))
@@ -19,7 +24,7 @@ This library provides some interfaces and a basic implementation of a State Engi
 The recommended and easiest way to install this library is through [Composer](https://getcomposer.org/):
 
 ```bash
-composer require uuf6429/state-engine-php "^1.0"
+composer require uuf6429/state-engine-php "^2.0"
 ```
 
 ## Why?
@@ -60,32 +65,26 @@ In this case, having the [`StateTraversion`](https://github.com/uuf6429/state-en
 Here's a quick & dirty example with the provided implementation (that assumes that there is a "door" model):
 
 ```php
-use App\Models\Door;  // example model
+use App\Models\Door;  // example model that implements StateAwareInterface
 
 use uuf6429\StateEngine\Implementation\Builder;
 use uuf6429\StateEngine\Implementation\Entities\State;
 
 $doorStateManager = Builder::create()
-    ->addState('open', 'Open')
-    ->addState('closed', 'Closed')
-    ->addState('locked', 'Locked')
-    ->addTransition('open', 'closed', 'Close the door')
-    ->addTransition('closed', 'locked', 'Lock the door')
-    ->addTransition('locked', 'closed', 'Unlock the door')
-    ->addTransition('closed', 'open', 'Open the door')
+    ->defState('open', 'Open')
+    ->defState('closed', 'Closed')
+    ->defState('locked', 'Locked')
+    ->defTransition('open', 'closed', 'Close the door')
+    ->defTransition('closed', 'locked', 'Lock the door')
+    ->defTransition('locked', 'closed', 'Unlock the door')
+    ->defTransition('closed', 'open', 'Open the door')
     ->getEngine(); // you can pass an event dispatcher to the engine here
 
 // find Door 123 (laravel-style repository-model)
 $door = Door::find(123);
 
-// build a state mutator (useful when the model does not have get/setState)
-$doorStateMutator = Builder::stateMutator(
-    static fn(): State => new State($door->status),                                    // getter
-    static fn(State $newState) => $door->update(['status' => $newState->getName()])    // setter
-);
-
 // close the door :)
-$doorStateManager->changeState($doorStateMutator, new State('closed'));
+$doorStateManager->changeState($door, new State('closed'));
 ```
 
 ### From Scratch (Custom)
@@ -100,6 +99,7 @@ For example, you could store states or transitions in a database, in which case
 The library provides some flexibility so that you can connect your existing code with it. In more complicated scenarios,
 you may have to build a small layer to bridge the gap. The example below illustrates how one can handle models with
 flags instead of a single state.
+
 ```php
 use App\Models\Door;  // example model
 
@@ -108,7 +108,7 @@ use uuf6429\StateEngine\Implementation\Entities\State;
 
 $door = Door::find(123);
 
-$doorStateMutator = Builder::stateMutator(
+$doorStateMutator = Builder::makeStateMutator(
     static function () use ($door): State {             // getter
         if ($door->is_locked) {
             return new State('locked');
@@ -125,12 +125,45 @@ $doorStateMutator = Builder::stateMutator(
         ]);
     }
 );
+
+// assumes engine $doorStateManager was already defined
+$doorStateManager->changeState($doorStateMutator, new State('closed'));
 ```
 
 ## Examples & Testing
 
-The [`JiraIssueTest`](https://github.com/uuf6429/state-engine-php/blob/main/test/JiraIssueTest.php) class serves as a test as well as a realistic example of how Jira Issue states could be set up.
+### [`JiraIssueTest`](https://github.com/uuf6429/state-engine-php/blob/main/tests/JiraIssueTest.php) State Engine
+
+This test provides a realistic example of how Jira Issue states could be set up.
 
 The test also generates the PlantUML diagram below (embedded as an image due to GFM limitations):
 
-![example](https://www.planttext.com/api/plantuml/svg/TPBDRiCW48JlFCKUauDV88SgZgfAlLIrymGqJ2rK31PiBENjYurfux_hpZVB370EB3tVMoF4uI9lFyOrHogA5pgKLff7qE589xgWqPRaD5cIxvPUqG_ScmnSi8ygVJjF2ZsCwrfO5a_xHbCDgHuZDNcpJZVNTWQCbUNlr1FLuBktn8w-qb0i5wuwV02AMkSHOx7K9cnR_ikaqhCEMLmqgCg1lyAg8L5Lxe8r36J0nbNvfEmwfqnNTjqyqZn5hf0IfGQCmDes8i-tDrTbZAGDr1xtb3sodpA4WTtG9rzmfeTAZpKg8vsdwmTr7QmGvtY9yJV-0W00)
+![jira issue example](https://www.planttext.com/api/plantuml/svg/TPBDRiCW48JlFCKUauDV88SgZgfAlLIrymGqJ2rK31PiBENjYurfux_hpZVB370EB3tVMoF4uI9lFyOrHogA5pgKLff7qE589xgWqPRaD5cIxvPUqG_ScmnSi8ygVJjF2ZsCwrfO5a_xHbCDgHuZDNcpJZVNTWQCbUNlr1FLuBktn8w-qb0i5wuwV02AMkSHOx7K9cnR_ikaqhCEMLmqgCg1lyAg8L5Lxe8r36J0nbNvfEmwfqnNTjqyqZn5hf0IfGQCmDes8i-tDrTbZAGDr1xtb3sodpA4WTtG9rzmfeTAZpKg8vsdwmTr7QmGvtY9yJV-0W00)
+
+### [`TurnstileTest`](https://github.com/uuf6429/state-engine-php/blob/main/tests/JiraIssueTest.php) State Machine
+
+This test illustrates how a [state machine](https://en.wikipedia.org/wiki/Finite-state_machine) can be used to model a [turnstile gate](https://en.wikipedia.org/wiki/Turnstile).
+As before, here's the generated diagram:
+
+![turnstile example](https://www.planttext.com/api/plantuml/svg/SoWkIImgAStDuUBIyCmjI2mkJapAITLKqDMrKz08W7Ej59ppC_CK2d8IarDJk90amEgGDLef1AGM5UVdAPGdvcGNAvHa5EMNfcTmSJcavgM0h040)
+
+Here's how the state machine definition looks like and is used:
+```php
+use App\Models\Turnstile;  // example model that implements StateAwareInterface
+
+use uuf6429\StateEngine\Implementation\Builder;
+
+$turnstileStateMachine = Builder::create()
+    // make states
+    ->defState('locked', 'Impassable')
+    ->defState('open', 'Passable')
+    // make transitions
+    ->defDataTransition('locked', ['insert_coin'], 'open', 'Coin placed')
+    ->defDataTransition('open', ['walk_through'], 'locked', 'Person walks through')
+    ->getMachine();
+
+$turnstile = Turnstile::find(123);
+
+// put coin in turnstile (notice that the final state is not mentioned)
+$turnstileStateMachine->processInput($turnstile, ['insert_coin']);
+```
diff --git a/composer.json b/composer.json
@@ -1,32 +1,40 @@
 {
-    "name": "uuf6429/state-engine",
-    "type": "library",
-    "homepage": "https://github.com/uuf6429/state-engine-php",
-    "readme": "README.md",
-    "license": "MIT",
-    "description": "A library providing interfaces and basic implementation of a State Engine",
-    "keywords": ["state", "engine", "state-engine", "uuf6429"],
-    "authors": [
-        {
-            "name": "Christian Sciberras",
-            "email": "[email protected]"
-        }
-    ],
-    "require": {
-        "php": "^7.4 || ^8.0",
-        "psr/event-dispatcher": "^1.0"
-    },
-    "require-dev": {
-        "phpunit/phpunit": "^9.5"
-    },
-    "autoload": {
-        "psr-4": {
-            "uuf6429\\StateEngine\\": "src/"
-        }
-    },
-    "autoload-dev": {
-        "psr-4": {
-            "uuf6429\\StateEngine\\": "test/"
-        }
+  "name": "uuf6429/state-engine",
+  "type": "library",
+  "homepage": "https://github.com/uuf6429/state-engine-php",
+  "readme": "README.md",
+  "license": "MIT",
+  "description": "A library providing interfaces and basic implementation of a State Engine or Machine",
+  "keywords": [
+    "state",
+    "engine",
+    "state-engine",
+    "machine",
+    "state-machine",
+    "workflow",
+    "uuf6429"
+  ],
+  "authors": [
+    {
+      "name": "Christian Sciberras",
+      "email": "[email protected]"
     }
+  ],
+  "require": {
+    "php": "^7.4 || ^8.0",
+    "psr/event-dispatcher": "^1.0"
+  },
+  "require-dev": {
+    "phpunit/phpunit": "^9.5"
+  },
+  "autoload": {
+    "psr-4": {
+      "uuf6429\\StateEngine\\": "src/"
+    }
+  },
+  "autoload-dev": {
+    "psr-4": {
+      "uuf6429\\StateEngine\\": "tests/"
+    }
+  }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
@@ -3,7 +3,7 @@
          xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.5/phpunit.xsd">
     <testsuites>
         <testsuite name="All Tests">
-            <directory>./test</directory>
+            <directory>./tests</directory>
         </testsuite>
     </testsuites>
     <coverage>

diff --git a/src/Exceptions/BuilderStateAlreadyDeclaredException.php b/src/Exceptions/BuilderStateAlreadyDeclaredException.php
@@ -2,10 +2,12 @@
 
 namespace uuf6429\StateEngine\Exceptions;
 
+use uuf6429\StateEngine\Interfaces\StateInterface;
+
 class BuilderStateAlreadyDeclaredException extends InvalidArgumentException
 {
-    public function __construct(string $name)
+    public function __construct(StateInterface $state)
     {
-        parent::__construct("Cannot add state \"$name\", it has already been declared.");
+        parent::__construct("Cannot add state \"$state\", it has already been declared.");
     }
 }
diff --git a/src/Exceptions/BuilderStateNotDeclaredException.php b/src/Exceptions/BuilderStateNotDeclaredException.php
@@ -2,10 +2,12 @@
 
 namespace uuf6429\StateEngine\Exceptions;
 
+use uuf6429\StateEngine\Interfaces\StateInterface;
+
 class BuilderStateNotDeclaredException extends InvalidArgumentException
 {
-    public function __construct(string $name)
+    public function __construct(StateInterface $state)
     {
-        parent::__construct("Cannot use state \"$name\", since it has not been declared yet.");
+        parent::__construct("Cannot use state \"$state\", since it has not been declared yet.");
     }
 }
diff --git a/src/Exceptions/BuilderTransitionAlreadyDeclaredException.php b/src/Exceptions/BuilderTransitionAlreadyDeclaredException.php
@@ -2,10 +2,12 @@
 
 namespace uuf6429\StateEngine\Exceptions;
 
+use uuf6429\StateEngine\Interfaces\TransitionInterface;
+
 class BuilderTransitionAlreadyDeclaredException extends InvalidArgumentException
 {
-    public function __construct(string $oldState, string $newState)
+    public function __construct(TransitionInterface $transition)
     {
-        parent::__construct("Cannot add transition from \"$oldState\" to \"$newState\", it has already been declared.");
+        parent::__construct("Cannot add transition \"$transition\", it has already been declared.");
     }
 }
diff --git a/src/Exceptions/TransitionNotAllowedException.php b/src/Exceptions/TransitionNotAllowedException.php
diff --git a/src/Exceptions/TransitionNotDeclaredException.php b/src/Exceptions/TransitionNotDeclaredException.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace uuf6429\StateEngine\Exceptions;
+
+use uuf6429\StateEngine\Interfaces\TransitionInterface;
+
+class TransitionNotDeclaredException extends RuntimeException
+{
+    public function __construct(TransitionInterface $transition)
+    {
+        parent::__construct("Cannot apply transition \"$transition\"; no such transition was defined.");
+    }
+}
diff --git a/src/Implementation/Engine.php → src/Implementation/AbstractEngine.php b/src/Implementation/Engine.php → src/Implementation/AbstractEngine.php
@@ -3,14 +3,14 @@
 namespace uuf6429\StateEngine\Implementation;
 
 use Psr\EventDispatcher\EventDispatcherInterface;
-use uuf6429\StateEngine\Exceptions\TransitionNotAllowedException;
+use uuf6429\StateEngine\Exceptions\TransitionNotDeclaredException;
 use uuf6429\StateEngine\Interfaces\EngineInterface;
 use uuf6429\StateEngine\Interfaces\StateInterface;
 use uuf6429\StateEngine\Interfaces\StateAwareInterface;
 use uuf6429\StateEngine\Interfaces\TransitionInterface;
 use uuf6429\StateEngine\Interfaces\TransitionRepositoryInterface;
 
-class Engine implements EngineInterface
+abstract class AbstractEngine implements EngineInterface
 {
     private TransitionRepositoryInterface $repository;
 
@@ -22,22 +22,16 @@ public function __construct(TransitionRepositoryInterface $repository, ?EventDis
         $this->dispatcher = $dispatcher;
     }
 
-    public function changeState(StateAwareInterface $item, StateInterface $newState): void
+    public function execute(StateAwareInterface $item, TransitionInterface $transition): void
     {
-        $transition = new Entities\Transition($item->getState(), $newState);
-        $this->applyTransition($item, $transition);
-    }
-
-    public function applyTransition(StateAwareInterface $item, TransitionInterface $transition): void
-    {
-        if (!$this->repository->has($transition)) {
-            throw new TransitionNotAllowedException($transition);
+        if (!($matched = $this->repository->find($transition))) {
+            throw new TransitionNotDeclaredException($transition);
         }
 
-        $this->dispatcher && $this->dispatcher->dispatch(new Events\StateChanging($item, $transition->getNewState()));
+        $this->dispatcher && $this->dispatcher->dispatch(new Events\StateChanging($item, $matched->getNewState()));
 
-        $item->setState($transition->getNewState());
+        $item->setState($matched->getNewState());
 
-        $this->dispatcher && $this->dispatcher->dispatch(new Events\StateChanged($item, $transition->getOldState()));
+        $this->dispatcher && $this->dispatcher->dispatch(new Events\StateChanged($item, $matched->getOldState()));
     }
 }