TreeBuildingRules example

            $dt = $impl->createDocumentType('html');
            // $this->doc = \DOMImplementation::createDocument(NULL, 'html', $dt);             $this->doc = $impl->createDocument(null, '', $dt);
            $this->doc->encoding = !empty($options['encoding']) ? $options['encoding'] : 'UTF-8';
        }

        $this->errors = array();

        $this->current = $this->doc; // ->documentElement;
        // Create a rules engine for tags.         $this->rules = new TreeBuildingRules();

        $implicitNS = array();
        if (isset($this->options[self::OPT_IMPLICIT_NS])) {
            $implicitNS = $this->options[self::OPT_IMPLICIT_NS];
        } elseif (isset($this->options['implicitNamespaces'])) {
            $implicitNS = $this->options['implicitNamespaces'];
        }

        // Fill $nsStack with the defalut HTML5 namespaces, plus the "implicitNamespaces" array taken form $options         array_unshift($this->nsStack, $implicitNS + array('' => self::NAMESPACE_HTML) + $this->implicitNamespaces);