Better AoT compiler

[weierophinney]

In order to improve AoT compiler, on my project I've done some changes.

The problem is that with AoT, dependency factories are not created. To accomplish my goal I've made a simple DependencyScanner that try to fetch every dependency classes:

<?php

declare(strict_types=1);

namespace AppAoT\Scanner;

use Zend\Code\Reflection\ClassReflection;

class DependencyScanner
{
    /** @var string[] */
    private $classNamesToScan;

    /** @var string[] */
    private $classNames = [];

    /** @var bool */
    private $isScanned = false;

    /**
     * DependencyScanner constructor.
     *
     * @param string[] $classNamesToScan
     */
    public function __construct(array $classNamesToScan = [])
    {
        $this->classNamesToScan = $classNamesToScan;
    }

    protected function scan(): void
    {
        if ($this->isScanned) {
            return;
        }

        foreach ($this->classNamesToScan as $className)
        {
            $this->scanClass($className);
        }

        $this->isScanned = true;
    }

    protected function scanClass(string $name): void
    {
        if (! \class_exists($name)) {
            return;
        }

        if (\array_key_exists($name, $this->classNames)) {
            return;
        }

        $this->classNames[$name] = true;

        $classReflection = new ClassReflection($name);
        $constructor = $classReflection->getConstructor();

        if (null === $constructor) {
            return;
        }

        $parameters = $constructor->getParameters();

        foreach ($parameters as $parameter) {
            $class = $parameter->getClass();

            if (null === $class) {
                continue;
            }

            $this->scanClass($class->getName());
        }
    }

    /**
     * @return string[]
     */
    public function getClassNames(): array
    {
        $this->scan();
        
        return \array_keys($this->classNames);
    }
}

And changed my di-generate-aot.sh to use it, getting every psr-4 namespace directory (does not support dir arrays yet), and using the previous class to fetch every dependency class.

<?php

namespace AppAoT;

use AppAoT\Scanner\DependencyScanner;
use Psr\Container\ContainerInterface;
use Zend\Code\Scanner\DirectoryScanner;
use Zend\Di\CodeGenerator\InjectorGenerator;
use Zend\Di\ConfigInterface;
use Zend\Di\Definition\RuntimeDefinition;
use Zend\Di\Resolver\DependencyResolver;

require __DIR__ . '/../vendor/autoload.php';

$composerFile = __DIR__ . '/../composer.json';

if (! \is_readable($composerFile)) {
    throw new \RuntimeException('Unable to find composer.json');
}

$composer = \json_decode(\file_get_contents($composerFile), true);
$directories = \array_values($composer['autoload']['psr-4'] ?? []);

/** @var ContainerInterface $container */
$container = require __DIR__ . '/../config/container.php';
$config = $container->get(ConfigInterface::class);

$resolver = new DependencyResolver(new RuntimeDefinition(), $config);
$resolver->setContainer($container);

$scanner = new DirectoryScanner($directories);

$dependencyScanner = new DependencyScanner($scanner->getClassNames());
$classNames = $dependencyScanner->getClassNames();

$generator = new InjectorGenerator($config, $resolver, __NAMESPACE__ . '\Generated');
$generator->setOutputDirectory(__DIR__ . '/../src/AppAoT/gen');
$generator->generate($classNames);

It's just an example, but I think we can include something like that in zend-code and/or here, and improve the documentation in order to provide a better AoT compiler compared to others compiled containers.

P.S. It does not resolve aliases yet.

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Originally posted by @thomasvargiu at zendframework/zend-di#42

[weierophinney]

Thanks for your ideas. This is an interesting feature. I guess we could achieve this by utilizing the dependency resolver and a recursive iterator.

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Originally posted by @tux-rampage at zendframework/zend-di#42 (comment)

[weierophinney]

@tux-rampage I think we need get rid of zend-code scanner as these are going to be removed, see: zendframework/zend-code#124

I've noticed it works wrong with configuration files, like:

<?php

return [
    'factories' => [
        'service' => ClassName::class,
    ],
];

it doesn't break zend-di, but we get wrong class names (as reported in closed issue linked above).

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Originally posted by @michalbundyra at zendframework/zend-di#42 (comment)

[weierophinney]

@webimpress thanks for pointing this out. I removed the zend-code bits for 3.1 and I am not planning to re-introduce it. I thought about roave's better reflection instead since they offer support for composer.json autoloaders. If you have any other suggestions, they'll be welcome.

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Originally posted by @tux-rampage at zendframework/zend-di#42 (comment)