WP_Rewrite::init()

1919	public function init() {1920		$this->extra_rules         = array();1921		$this->non_wp_rules        = array();1922		$this->endpoints           = array();1923		$this->permalink_structure = get_option( 'permalink_structure' );1924		$this->front               = substr( $this->permalink_structure, 0, strpos( $this->permalink_structure, '%' ) );1925		$this->root                = '';1926 1927		if ( $this->using_index_permalinks() ) {1928			$this->root = $this->index . '/';1929		}1930 1931		unset( $this->author_structure );1932		unset( $this->date_structure );1933		unset( $this->page_structure );1934		unset( $this->search_structure );1935		unset( $this->feed_structure );1936		unset( $this->comment_feed_structure );1937 1938		$this->use_trailing_slashes = str_ends_with( $this->permalink_structure, '/' );1939 1940		// Enable generic rules for pages if permalink structure doesn't begin with a wildcard.1941		if ( preg_match( '/^[^%]*%(?:postname|category|tag|author)%/', $this->permalink_structure ) ) {1942			$this->use_verbose_page_rules = true;1943		} else {1944			$this->use_verbose_page_rules = false;1945		}1946	}