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    <h3>Editing: Manager.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php

namespace Illuminate\Support;

use Closure;
use Illuminate\Contracts\Container\Container;
use InvalidArgumentException;

abstract class Manager
{
    /**
     * The container instance.
     *
     * @var \Illuminate\Contracts\Container\Container
     */
    protected $container;

    /**
     * The configuration repository instance.
     *
     * @var \Illuminate\Contracts\Config\Repository
     */
    protected $config;

    /**
     * The registered custom driver creators.
     *
     * @var array
     */
    protected $customCreators = [];

    /**
     * The array of created &quot;drivers&quot;.
     *
     * @var array
     */
    protected $drivers = [];

    /**
     * Create a new manager instance.
     *
     * @param  \Illuminate\Contracts\Container\Container  $container
     * @return void
     */
    public function __construct(Container $container)
    {
        $this-&gt;container = $container;
        $this-&gt;config = $container-&gt;make('config');
    }

    /**
     * Get the default driver name.
     *
     * @return string
     */
    abstract public function getDefaultDriver();

    /**
     * Get a driver instance.
     *
     * @param  string|null  $driver
     * @return mixed
     *
     * @throws \InvalidArgumentException
     */
    public function driver($driver = null)
    {
        $driver = $driver ?: $this-&gt;getDefaultDriver();

        if (is_null($driver)) {
            throw new InvalidArgumentException(sprintf(
                'Unable to resolve NULL driver for [%s].', static::class
            ));
        }

        // If the given driver has not been created before, we will create the instances
        // here and cache it so we can return it next time very quickly. If there is
        // already a driver created by this name, we'll just return that instance.
        if (! isset($this-&gt;drivers[$driver])) {
            $this-&gt;drivers[$driver] = $this-&gt;createDriver($driver);
        }

        return $this-&gt;drivers[$driver];
    }

    /**
     * Create a new driver instance.
     *
     * @param  string  $driver
     * @return mixed
     *
     * @throws \InvalidArgumentException
     */
    protected function createDriver($driver)
    {
        // First, we will determine if a custom driver creator exists for the given driver and
        // if it does not we will check for a creator method for the driver. Custom creator
        // callbacks allow developers to build their own &quot;drivers&quot; easily using Closures.
        if (isset($this-&gt;customCreators[$driver])) {
            return $this-&gt;callCustomCreator($driver);
        } else {
            $method = 'create'.Str::studly($driver).'Driver';

            if (method_exists($this, $method)) {
                return $this-&gt;$method();
            }
        }

        throw new InvalidArgumentException(&quot;Driver [$driver] not supported.&quot;);
    }

    /**
     * Call a custom driver creator.
     *
     * @param  string  $driver
     * @return mixed
     */
    protected function callCustomCreator($driver)
    {
        return $this-&gt;customCreators[$driver]($this-&gt;container);
    }

    /**
     * Register a custom driver creator Closure.
     *
     * @param  string  $driver
     * @param  \Closure  $callback
     * @return $this
     */
    public function extend($driver, Closure $callback)
    {
        $this-&gt;customCreators[$driver] = $callback;

        return $this;
    }

    /**
     * Get all of the created &quot;drivers&quot;.
     *
     * @return array
     */
    public function getDrivers()
    {
        return $this-&gt;drivers;
    }

    /**
     * Get the container instance used by the manager.
     *
     * @return \Illuminate\Contracts\Container\Container
     */
    public function getContainer()
    {
        return $this-&gt;container;
    }

    /**
     * Set the container instance used by the manager.
     *
     * @param  \Illuminate\Contracts\Container\Container  $container
     * @return $this
     */
    public function setContainer(Container $container)
    {
        $this-&gt;container = $container;

        return $this;
    }

    /**
     * Forget all of the resolved driver instances.
     *
     * @return $this
     */
    public function forgetDrivers()
    {
        $this-&gt;drivers = [];

        return $this;
    }

    /**
     * Dynamically call the default driver instance.
     *
     * @param  string  $method
     * @param  array  $parameters
     * @return mixed
     */
    public function __call($method, $parameters)
    {
        return $this-&gt;driver()-&gt;$method(...$parameters);
    }
}
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