Source

File: wp-includes/class-wp-rewrite.php

public function rewrite_rules() {
		$rewrite = array();

		if ( empty( $this->permalink_structure ) ) {
			return $rewrite;
		}

		// robots.txt -- only if installed at the root.
		$home_path      = parse_url( home_url() );
		$robots_rewrite = ( empty( $home_path['path'] ) || '/' === $home_path['path'] ) ? array( 'robots\.txt$' => $this->index . '?robots=1' ) : array();

		// favicon.ico -- only if installed at the root.
		$favicon_rewrite = ( empty( $home_path['path'] ) || '/' === $home_path['path'] ) ? array( 'favicon\.ico$' => $this->index . '?favicon=1' ) : array();

		// Old feed and service files.
		$deprecated_files = array(
			'.*wp-(atom|rdf|rss|rss2|feed|commentsrss2)\.php$' => $this->index . '?feed=old',
			'.*wp-app\.php(/.*)?$' => $this->index . '?error=403',
		);

		// Registration rules.
		$registration_pages = array();
		if ( is_multisite() && is_main_site() ) {
			$registration_pages['.*wp-signup.php$']   = $this->index . '?signup=true';
			$registration_pages['.*wp-activate.php$'] = $this->index . '?activate=true';
		}

		// Deprecated.
		$registration_pages['.*wp-register.php$'] = $this->index . '?register=true';

		// Post rewrite rules.
		$post_rewrite = $this->generate_rewrite_rules( $this->permalink_structure, EP_PERMALINK );

		/**
		 * Filters rewrite rules used for "post" archives.
		 *
		 * @since 1.5.0
		 *
		 * @param string[] $post_rewrite Array of rewrite rules for posts, keyed by their regex pattern.
		 */
		$post_rewrite = apply_filters( 'post_rewrite_rules', $post_rewrite );

		// Date rewrite rules.
		$date_rewrite = $this->generate_rewrite_rules( $this->get_date_permastruct(), EP_DATE );

		/**
		 * Filters rewrite rules used for date archives.
		 *
		 * Likely date archives would include /yyyy/, /yyyy/mm/, and /yyyy/mm/dd/.
		 *
		 * @since 1.5.0
		 *
		 * @param string[] $date_rewrite Array of rewrite rules for date archives, keyed by their regex pattern.
		 */
		$date_rewrite = apply_filters( 'date_rewrite_rules', $date_rewrite );

		// Root-level rewrite rules.
		$root_rewrite = $this->generate_rewrite_rules( $this->root . '/', EP_ROOT );

		/**
		 * Filters rewrite rules used for root-level archives.
		 *
		 * Likely root-level archives would include pagination rules for the homepage
		 * as well as site-wide post feeds (e.g. /feed/, and /feed/atom/).
		 *
		 * @since 1.5.0
		 *
		 * @param string[] $root_rewrite Array of root-level rewrite rules, keyed by their regex pattern.
		 */
		$root_rewrite = apply_filters( 'root_rewrite_rules', $root_rewrite );

		// Comments rewrite rules.
		$comments_rewrite = $this->generate_rewrite_rules( $this->root . $this->comments_base, EP_COMMENTS, false, true, true, false );

		/**
		 * Filters rewrite rules used for comment feed archives.
		 *
		 * Likely comments feed archives include /comments/feed/, and /comments/feed/atom/.
		 *
		 * @since 1.5.0
		 *
		 * @param string[] $comments_rewrite Array of rewrite rules for the site-wide comments feeds, keyed by their regex pattern.
		 */
		$comments_rewrite = apply_filters( 'comments_rewrite_rules', $comments_rewrite );

		// Search rewrite rules.
		$search_structure = $this->get_search_permastruct();
		$search_rewrite   = $this->generate_rewrite_rules( $search_structure, EP_SEARCH );

		/**
		 * Filters rewrite rules used for search archives.
		 *
		 * Likely search-related archives include /search/search+query/ as well as
		 * pagination and feed paths for a search.
		 *
		 * @since 1.5.0
		 *
		 * @param string[] $search_rewrite Array of rewrite rules for search queries, keyed by their regex pattern.
		 */
		$search_rewrite = apply_filters( 'search_rewrite_rules', $search_rewrite );

		// Author rewrite rules.
		$author_rewrite = $this->generate_rewrite_rules( $this->get_author_permastruct(), EP_AUTHORS );

		/**
		 * Filters rewrite rules used for author archives.
		 *
		 * Likely author archives would include /author/author-name/, as well as
		 * pagination and feed paths for author archives.
		 *
		 * @since 1.5.0
		 *
		 * @param string[] $author_rewrite Array of rewrite rules for author archives, keyed by their regex pattern.
		 */
		$author_rewrite = apply_filters( 'author_rewrite_rules', $author_rewrite );

		// Pages rewrite rules.
		$page_rewrite = $this->page_rewrite_rules();

		/**
		 * Filters rewrite rules used for "page" post type archives.
		 *
		 * @since 1.5.0
		 *
		 * @param string[] $page_rewrite Array of rewrite rules for the "page" post type, keyed by their regex pattern.
		 */
		$page_rewrite = apply_filters( 'page_rewrite_rules', $page_rewrite );

		// Extra permastructs.
		foreach ( $this->extra_permastructs as $permastructname => $struct ) {
			if ( is_array( $struct ) ) {
				if ( count( $struct ) == 2 ) {
					$rules = $this->generate_rewrite_rules( $struct[0], $struct[1] );
				} else {
					$rules = $this->generate_rewrite_rules( $struct['struct'], $struct['ep_mask'], $struct['paged'], $struct['feed'], $struct['forcomments'], $struct['walk_dirs'], $struct['endpoints'] );
				}
			} else {
				$rules = $this->generate_rewrite_rules( $struct );
			}

			/**
			 * Filters rewrite rules used for individual permastructs.
			 *
			 * The dynamic portion of the hook name, `$permastructname`, refers
			 * to the name of the registered permastruct, e.g. 'post_tag' (tags),
			 * 'category' (categories), etc.
			 *
			 * @since 3.1.0
			 *
			 * @param string[] $rules Array of rewrite rules generated for the current permastruct, keyed by their regex pattern.
			 */
			$rules = apply_filters( "{$permastructname}_rewrite_rules", $rules );

			if ( 'post_tag' === $permastructname ) {

				/**
				 * Filters rewrite rules used specifically for Tags.
				 *
				 * @since 2.3.0
				 * @deprecated 3.1.0 Use {@see 'post_tag_rewrite_rules'} instead.
				 *
				 * @param string[] $rules Array of rewrite rules generated for tags, keyed by their regex pattern.
				 */
				$rules = apply_filters_deprecated( 'tag_rewrite_rules', array( $rules ), '3.1.0', 'post_tag_rewrite_rules' );
			}

			$this->extra_rules_top = array_merge( $this->extra_rules_top, $rules );
		}

		// Put them together.
		if ( $this->use_verbose_page_rules ) {
			$this->rules = array_merge( $this->extra_rules_top, $robots_rewrite, $favicon_rewrite, $deprecated_files, $registration_pages, $root_rewrite, $comments_rewrite, $search_rewrite, $author_rewrite, $date_rewrite, $page_rewrite, $post_rewrite, $this->extra_rules );
		} else {
			$this->rules = array_merge( $this->extra_rules_top, $robots_rewrite, $favicon_rewrite, $deprecated_files, $registration_pages, $root_rewrite, $comments_rewrite, $search_rewrite, $author_rewrite, $date_rewrite, $post_rewrite, $page_rewrite, $this->extra_rules );
		}

		/**
		 * Fires after the rewrite rules are generated.
		 *
		 * @since 1.5.0
		 *
		 * @param WP_Rewrite $this Current WP_Rewrite instance (passed by reference).
		 */
		do_action_ref_array( 'generate_rewrite_rules', array( &$this ) );

		/**
		 * Filters the full set of generated rewrite rules.
		 *
		 * @since 1.5.0
		 *
		 * @param string[] $rules The compiled array of rewrite rules, keyed by their regex pattern.
		 */
		$this->rules = apply_filters( 'rewrite_rules_array', $this->rules );

		return $this->rules;
	}