Get namespace from file path

extractNamespace.php

<?php

/**
 * Extract namespace from a PHP file
 *
 * @param  string $file
 * @return string
 */
public function extractNamespace(string $file) : string
{
    $contents = file_exists($file) ? file_get_contents($file) : $file;
    $namespace = $class = '';
    $getting_namespace = $getting_class = false;

    foreach (token_get_all($contents) as $token) {

        if (is_array($token) && $token[0] == T_NAMESPACE) {
            $getting_namespace = true;
        }

        if (is_array($token) && $token[0] == T_CLASS) {
            $getting_class = true;
        }

        // While we're grabbing the namespace name...
        if ($getting_namespace === true) {
            if (is_array($token) && in_array($token[0], [T_STRING, T_NS_SEPARATOR])) {
                $namespace .= $token[1];
            } else if ($token === ';') {
                $getting_namespace = false;
            }
        }

        if ($getting_class === true) {
            if (is_array($token) && $token[0] == T_STRING) {
                $class = $token[1];
                break;
            }
        }
    }

    return $namespace ? $namespace . '\\' . $class : $class;

}