Directive interpolation in Magento 2

SomeClass.php

class SomeClass
{
    public function __construct(
        \Magento\Framework\Filter\Template $templateFilter
    )
    {
        $this->templateFilter = $templateFilter;
    }

    public function getDirectiveContent()
    {
        return $this->templateFilter
            ->setVariables(['who' => 'World'])
            ->filter('Hello {{var who}}');

        // Hello World
    }
}