src/I18n/GettextPoFile.php
public function getCategories()
    {
        if (!isset($this->_messages)) {
            $this->loadAll();
        }
        $categories = array_keys($this->_messages);
        sort($categories);
        return $categories;
    }
public function getCategories()
    {
        if (!isset($this->_messages)) {
            $this->loadAll();
        }
        $categories = array_keys($this->_messages);
        sort($categories);
        return $categories;
    }
Get all categories list
@return string[]