Lightweight static constructor initialiser (#7)

* Implement very lightweight static constructor initialiser with custom SPL autoloader w/o reflections.
* Remove unneeded dependency on 
* Update documentation
* Covered with tests

Author: dbalabka

README.md

@@ -26,9 +26,10 @@ final class Action extends Enumeration
     public static $view;
     public static $edit;
 }
-// to avoid manual initialization you can setup the "vladimmi/construct-static" custom loader
 Action::initialize();
 ```
+**Note!** You should always call the `Enumeration::initialize()` method right after Enumeration Class declaration.
+To avoid manual initialization you can setup the [StaticConstructorLoader](#class-static-initialization) provided in this library.
 
 Declaration with Typed Properties support:
 ```php
@@ -129,7 +130,7 @@ multiple Enumeration classes.
 3. Implementation is based on assumption that all class static properties are elements of Enum. <!-- If there is a need to declare
 any static property that isn't an Enum element then you should override the `\Dbalabka\Enumeration\Enumeration::$notEnumVars` method. -->
 4. The method `Dbalabka\Enumeration\Enumeration::initialize()` should be called after each Enumeration class declaration. Please use the 
-[vladimmi/construct-static](https://github.com/vladimmi/construct-static) custom loader to avoid boilerplate code.
+[StaticConstructorLoader](#class-static-initialization) provided in this library to avoid boilerplate code.
 
 ## Usage
 ```php
@@ -168,17 +169,19 @@ Action::$view = null;
 
 ### Class static initialization 
 This implementation relies on class static initialization which was proposed in [Static Class Constructor](https://wiki.php.net/rfc/static_class_constructor).
-The RFC describes possible workarounds. The simplest way is to call the initialization method right after class declaration, 
+The RFC is still in Draft status but it describes possible workarounds. The simplest way is to call the initialization method right after the class declaration, 
 but it requires the developer to keep this in mind. Thanks to [Typed Properties](https://wiki.php.net/rfc/typed_properties_v2)
-we can control uninitialized properties - PHP will throw and error in case of access to an uninitialized property.
-It might be automated with custom autoloader implemented in [vladimmi/construct-static](https://github.com/vladimmi/construct-static) library.
+we can control uninitialized properties - PHP will throw an error in case of access to an uninitialized property.
+It might be automated with custom autoloader [Dbalabka\StaticConstructorLoader\StaticConstructorLoader](./src/StaticConstructorLoader/StaticConstructorLoader.php) 
+provided in this library:
 ```php
-<?php
-// You should always call the initialize() method right after class declaration
-// To avoid manual initialization you can setup the "vladimmi/construct-static" custom loader
-Action::initialize();
-```
-See [examples/class_static_construct.php](examples/class_static_construct.php) for example to overcome this limitation. 
+<?php 
+use Dbalabka\StaticConstructorLoader\StaticConstructorLoader;
+
+$composer = require_once(__DIR__ . '/vendor/autoload.php');
+$loader = new StaticConstructorLoader($composer);
+``` 
+See [examples/class_static_construct.php](examples/class_static_construct.php) for example. 
 
 ### Serialization
 There is no possibility to serialize the singleton. As a result, we have to restrict direct Enum object serialization.

composer.json

@@ -13,23 +13,20 @@
         "php": ">=7.1"
     },
     "require-dev": {
-        "vladimmi/construct-static": "dev-master",
         "myclabs/php-enum": "^1.0",
         "phpunit/phpunit": "^7.5",
         "phpbench/phpbench": "^0.16.9"
     },
-    "suggest": {
-        "vladimmi/construct-static": "Allows to call __constructStatic on class load"
-    },
     "autoload": {
         "psr-4": {
-            "Dbalabka\\Enumeration\\": "src"
+            "Dbalabka\\": "src"
         }
     },
     "autoload-dev": {
         "psr-4": {
             "Dbalabka\\Enumeration\\Examples\\": "examples",
-            "Dbalabka\\Enumeration\\Tests\\": "tests"
+            "Dbalabka\\Enumeration\\Tests\\": "tests\\Enumeration",
+            "Dbalabka\\StaticConstructorLoader\\Tests\\": "tests\\StaticConstructorLoader"
         }
     }
 }

examples/class_static_construct.php

@@ -2,8 +2,9 @@
 declare(strict_types=1);
 
 use Dbalabka\Enumeration\Examples\Enum\Color;
+use Dbalabka\StaticConstructorLoader\StaticConstructorLoader;
 
 $composer = require_once(__DIR__ . '/../vendor/autoload.php');
-$loader = new ConstructStatic\Loader($composer);
+$loader = new StaticConstructorLoader($composer);
 
 assert(Color::$red instanceof Color && Color::$red === Color::$red);

src/Enumeration.php renamed to src/Enumeration/Enumeration.php

@@ -5,6 +5,7 @@
 
 use Dbalabka\Enumeration\Exception\EnumerationException;
 use Dbalabka\Enumeration\Exception\InvalidArgumentException;
+use Dbalabka\StaticConstructorLoader\StaticConstructorInterface;
 use function array_search;
 use function get_class_vars;
 use function sprintf;
@@ -17,7 +18,7 @@
  *
  * @author Dmitry Balabka <dmitry.balabka@gmail.com>
  */
-abstract class Enumeration
+abstract class Enumeration implements StaticConstructorInterface
 {
     const INITIAL_ORDINAL = 0;
 
@@ -28,13 +29,7 @@ abstract class Enumeration
 
     private static $initializedEnums = [];
 
-    /**
-     * This method should be called right after enumerate class declaration.
-     * Unfortunately, PHP does not support static initialization.
-     * See static init RFC: https://wiki.php.net/rfc/static_class_constructor
-     * Typed Properties will help to control of calling this method.
-     */
-    final protected static function __constructStatic() : void
+    final public static function __constructStatic() : void
     {
         if (self::class === static::class) {
             return;

src/Exception/EnumerationException.php renamed to src/Enumeration/Exception/EnumerationException.php

@@ -0,0 +1,12 @@
+<?php
+declare(strict_types=1);
+
+namespace Dbalabka\StaticConstructorLoader\Exception;
+
+/**
+ * @author Dmitrijs Balabka <dmitry.balabka@gmail.com>
+ */
+class StaticConstructorLoaderException extends \Exception
+{
+
+}

src/Exception/InvalidArgumentException.php renamed to src/Enumeration/Exception/InvalidArgumentException.php

@@ -0,0 +1,17 @@
+<?php
+declare(strict_types=1);
+
+namespace Dbalabka\StaticConstructorLoader;
+
+/**
+ * @author Dmitrijs Balabka <dmitry.balabka@gmail.com>
+ */
+interface StaticConstructorInterface
+{
+    /**
+     * This method should be called right after enumerate class declaration.
+     * Unfortunately, PHP does not support static initialization.
+     * See static init RFC: https://wiki.php.net/rfc/static_class_constructor
+     */
+    public static function __constructStatic();
+}

src/StaticConstructorLoader/Exception/StaticConstructorLoaderException.php

@@ -0,0 +1,64 @@
+<?php
+declare(strict_types=1);
+
+namespace Dbalabka\StaticConstructorLoader;
+
+use Composer\Autoload\ClassLoader;
+use Dbalabka\StaticConstructorLoader\Exception\StaticConstructorLoaderException;
+
+/**
+ * Decorates the Composer autoloader to statically initialize the class.
+ * This is a very lightweight workaround which is described in https://wiki.php.net/rfc/static_class_constructor
+ *
+ * @author Dmitrijs Balabka <dmitry.balabka@gmail.com>
+ */
+final class StaticConstructorLoader
+{
+    /**
+     * @var ClassLoader
+     */
+    private $classLoader;
+
+    public function __construct(ClassLoader $classLoader)
+    {
+        $this->classLoader = $classLoader;
+
+        // find Composer autoloader
+        $loaders = spl_autoload_functions();
+        $otherLoaders = [];
+        $composerLoader = null;
+        foreach ($loaders as $loader) {
+            if (is_array($loader)) {
+                if ($loader[0] === $classLoader) {
+                    $composerLoader = $loader;
+                    break;
+                }
+                if ($loader[0] instanceof self) {
+                    throw new StaticConstructorLoaderException(sprintf('%s already registered', self::class));
+                }
+            }
+            $otherLoaders[] = $loader;
+        }
+
+        if (!$composerLoader) {
+            throw new StaticConstructorLoaderException(sprintf('%s was not found in registered autoloaders', ClassLoader::class));
+        }
+
+        // unregister Composer autoloader and all preceding autoloaders
+        array_map('spl_autoload_unregister', array_merge($otherLoaders, [$composerLoader]));
+
+        // restore the original queue order
+        $loadersToRestore = array_merge([[$this, 'loadClass']], array_reverse($otherLoaders));
+        $flagTrue = array_fill(0, count($loadersToRestore), true);
+        array_map('spl_autoload_register', $loadersToRestore, $flagTrue, $flagTrue);
+    }
+
+    public function loadClass($className)
+    {
+        $result = $this->classLoader->loadClass($className);
+        if ($result === true && $className !== StaticConstructorInterface::class && is_a($className, StaticConstructorInterface::class, true)) {
+            $className::__constructStatic();
+        }
+        return $result;
+    }
+}