View file vendor/php-di/invoker/src/ParameterResolver/DefaultValueResolver.php

<?php

namespace Invoker\ParameterResolver;

use ReflectionException;
use ReflectionFunctionAbstract;

/**
 * Finds the default value for a parameter, *if it exists*.
 *
 * @author Matthieu Napoli <[email protected]>
 */
class DefaultValueResolver implements ParameterResolver
{
    public function getParameters(
        ReflectionFunctionAbstract $reflection,
        array $providedParameters,
        array $resolvedParameters
    ) {
        $parameters = $reflection->getParameters();

        // Skip parameters already resolved
        if (! empty($resolvedParameters)) {
            $parameters = array_diff_key($parameters, $resolvedParameters);
        }

        foreach ($parameters as $index => $parameter) {
            /** @var \ReflectionParameter $parameter */
            if ($parameter->isOptional()) {
                try {
                    $resolvedParameters[$index] = $parameter->getDefaultValue();
                } catch (ReflectionException $e) {
                    // Can't get default values from PHP internal classes and functions
                }
            }
        }

        return $resolvedParameters;
    }
}