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    <h3>Editing: ReflectsClosures.php</h3>
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namespace Illuminate\Support\Traits;

use Closure;
use Illuminate\Support\Reflector;
use ReflectionFunction;
use RuntimeException;

trait ReflectsClosures
{
    /**
     * Get the class name of the first parameter of the given Closure.
     *
     * @param  \Closure  $closure
     * @return string
     *
     * @throws \ReflectionException
     * @throws \RuntimeException
     */
    protected function firstClosureParameterType(Closure $closure)
    {
        $types = array_values($this-&gt;closureParameterTypes($closure));

        if (! $types) {
            throw new RuntimeException('The given Closure has no parameters.');
        }

        if ($types[0] === null) {
            throw new RuntimeException('The first parameter of the given Closure is missing a type hint.');
        }

        return $types[0];
    }

    /**
     * Get the class names of the first parameter of the given Closure, including union types.
     *
     * @param  \Closure  $closure
     * @return array
     *
     * @throws \ReflectionException
     * @throws \RuntimeException
     */
    protected function firstClosureParameterTypes(Closure $closure)
    {
        $reflection = new ReflectionFunction($closure);

        $types = collect($reflection-&gt;getParameters())-&gt;mapWithKeys(function ($parameter) {
            if ($parameter-&gt;isVariadic()) {
                return [$parameter-&gt;getName() =&gt; null];
            }

            return [$parameter-&gt;getName() =&gt; Reflector::getParameterClassNames($parameter)];
        })-&gt;filter()-&gt;values()-&gt;all();

        if (empty($types)) {
            throw new RuntimeException('The given Closure has no parameters.');
        }

        if (isset($types[0]) &amp;&amp; empty($types[0])) {
            throw new RuntimeException('The first parameter of the given Closure is missing a type hint.');
        }

        return $types[0];
    }

    /**
     * Get the class names / types of the parameters of the given Closure.
     *
     * @param  \Closure  $closure
     * @return array
     *
     * @throws \ReflectionException
     */
    protected function closureParameterTypes(Closure $closure)
    {
        $reflection = new ReflectionFunction($closure);

        return collect($reflection-&gt;getParameters())-&gt;mapWithKeys(function ($parameter) {
            if ($parameter-&gt;isVariadic()) {
                return [$parameter-&gt;getName() =&gt; null];
            }

            return [$parameter-&gt;getName() =&gt; Reflector::getParameterClassName($parameter)];
        })-&gt;all();
    }
}
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