PhpParser\ParserAbstract::getNamespacingStyle PHP Method

    private function getNamespacingStyle(array $stmts) {
        $style = null;
        $hasNotAllowedStmts = false;
        foreach ($stmts as $i => $stmt) {
            if ($stmt instanceof Node\Stmt\Namespace_) {
                $currentStyle = null === $stmt->stmts ? 'semicolon' : 'brace';
                if (null === $style) {
                    $style = $currentStyle;
                    if ($hasNotAllowedStmts) {
                        $this->emitError(new Error(
                            'Namespace declaration statement has to be the very first statement in the script',
                            $stmt->getLine() // Avoid marking the entire namespace as an error
                        ));
                    }
                } elseif ($style !== $currentStyle) {
                    $this->emitError(new Error(
                        'Cannot mix bracketed namespace declarations with unbracketed namespace declarations',
                        $stmt->getLine() // Avoid marking the entire namespace as an error
                    ));
                    // Treat like semicolon style for namespace normalization
                    return 'semicolon';
                }
                continue;
            }

            /* declare(), __halt_compiler() and nops can be used before a namespace declaration */
            if ($stmt instanceof Node\Stmt\Declare_
                || $stmt instanceof Node\Stmt\HaltCompiler
                || $stmt instanceof Node\Stmt\Nop) {
                continue;
            }

            /* There may be a hashbang line at the very start of the file */
            if ($i == 0 && $stmt instanceof Node\Stmt\InlineHTML && preg_match('/\A#!.*\r?\n\z/', $stmt->value)) {
                continue;
            }

            /* Everything else if forbidden before namespace declarations */
            $hasNotAllowedStmts = true;
        }
        return $style;
    }