Neos\FluidAdaptor\Core\Parser\TemplateProcessor\NamespaceDetectionTemplateProcessor::registerNamespacesFromTemplateSource PHP Method

    public function registerNamespacesFromTemplateSource($templateSource)
    {
        $viewHelperResolver = $this->renderingContext->getViewHelperResolver();
        if (preg_match_all(static::SPLIT_PATTERN_TEMPLATE_OPEN_NAMESPACETAG, $templateSource, $matchedVariables, PREG_SET_ORDER) > 0) {
            foreach ($matchedVariables as $namespaceMatch) {
                $viewHelperNamespace = $this->renderingContext->getTemplateParser()->unquoteString($namespaceMatch[2]);
                $phpNamespace = $viewHelperResolver->resolvePhpNamespaceFromFluidNamespace($viewHelperNamespace);
                if (stristr($phpNamespace, '/') === false) {
                    $viewHelperResolver->addNamespace($namespaceMatch[1], $phpNamespace);
                }
            }
        }
        $templateSource = preg_replace_callback(static::NAMESPACE_DECLARATION, function (array $matches) use($viewHelperResolver) {
            $identifier = $matches['identifier'];
            $namespace = isset($matches['phpNamespace']) ? $matches['phpNamespace'] : null;
            if (strlen($namespace) === 0) {
                $namespace = null;
            }
            $viewHelperResolver->addNamespace($identifier, $namespace);
            return '';
        }, $templateSource);
        return $templateSource;
    }