WP_Rewrite::init()

	public function init() {
		$this->extra_rules = $this->non_wp_rules = $this->endpoints = array();
		$this->permalink_structure = get_option('permalink_structure');
		$this->front = substr($this->permalink_structure, 0, strpos($this->permalink_structure, '%'));
		$this->root = '';

		if ( $this->using_index_permalinks() )
			$this->root = $this->index . '/';

		unset($this->author_structure);
		unset($this->date_structure);
		unset($this->page_structure);
		unset($this->search_structure);
		unset($this->feed_structure);
		unset($this->comment_feed_structure);
		$this->use_trailing_slashes = ( '/' == substr($this->permalink_structure, -1, 1) );

		// Enable generic rules for pages if permalink structure doesn't begin with a wildcard.
		if ( preg_match("/^[^%]*%(?:postname|category|tag|author)%/", $this->permalink_structure) )
			 $this->use_verbose_page_rules = true;
		else
			$this->use_verbose_page_rules = false;
	}