WP::parse_request

	public function parse_request( $extra_query_vars = '' ) {
		global $wp_rewrite;

		/**
		 * Filters whether to parse the request.
		 *
		 * @since 3.5.0
		 *
		 * @param bool         $bool             Whether or not to parse the request. Default true.
		 * @param WP           $this             Current WordPress environment instance.
		 * @param array|string $extra_query_vars Extra passed query variables.
		 */
		if ( ! apply_filters( 'do_parse_request', true, $this, $extra_query_vars ) ) {
			return;
		}

		$this->query_vars     = array();
		$post_type_query_vars = array();

		if ( is_array( $extra_query_vars ) ) {
			$this->extra_query_vars = & $extra_query_vars;
		} elseif ( ! empty( $extra_query_vars ) ) {
			parse_str( $extra_query_vars, $this->extra_query_vars );
		}
		// Process PATH_INFO, REQUEST_URI, and 404 for permalinks.

		// Fetch the rewrite rules.
		$rewrite = $wp_rewrite->wp_rewrite_rules();

		if ( ! empty( $rewrite ) ) {
			// If we match a rewrite rule, this will be cleared.
			$error               = '404';
			$this->did_permalink = true;

			$pathinfo         = isset( $_SERVER['PATH_INFO'] ) ? $_SERVER['PATH_INFO'] : '';
			list( $pathinfo ) = explode( '?', $pathinfo );
			$pathinfo         = str_replace( '%', '%25', $pathinfo );

			list( $req_uri ) = explode( '?', $_SERVER['REQUEST_URI'] );
			$self            = $_SERVER['PHP_SELF'];
			$home_path       = trim( parse_url( home_url(), PHP_URL_PATH ), '/' );
			$home_path_regex = sprintf( '|^%s|i', preg_quote( $home_path, '|' ) );

			/*
			 * Trim path info from the end and the leading home path from the front.
			 * For path info requests, this leaves us with the requesting filename, if any.
			 * For 404 requests, this leaves us with the requested permalink.
			 */
			$req_uri  = str_replace( $pathinfo, '', $req_uri );
			$req_uri  = trim( $req_uri, '/' );
			$req_uri  = preg_replace( $home_path_regex, '', $req_uri );
			$req_uri  = trim( $req_uri, '/' );
			$pathinfo = trim( $pathinfo, '/' );
			$pathinfo = preg_replace( $home_path_regex, '', $pathinfo );
			$pathinfo = trim( $pathinfo, '/' );
			$self     = trim( $self, '/' );
			$self     = preg_replace( $home_path_regex, '', $self );
			$self     = trim( $self, '/' );

			// The requested permalink is in $pathinfo for path info requests and
			// $req_uri for other requests.
			if ( ! empty( $pathinfo ) && ! preg_match( '|^.*' . $wp_rewrite->index . '$|', $pathinfo ) ) {
				$requested_path = $pathinfo;
			} else {
				// If the request uri is the index, blank it out so that we don't try to match it against a rule.
				if ( $req_uri == $wp_rewrite->index ) {
					$req_uri = '';
				}
				$requested_path = $req_uri;
			}
			$requested_file = $req_uri;

			$this->request = $requested_path;

			// Look for matches.
			$request_match = $requested_path;
			if ( empty( $request_match ) ) {
				// An empty request could only match against ^$ regex.
				if ( isset( $rewrite['$'] ) ) {
					$this->matched_rule = '$';
					$query              = $rewrite['$'];
					$matches            = array( '' );
				}
			} else {
				foreach ( (array) $rewrite as $match => $query ) {
					// If the requested file is the anchor of the match, prepend it to the path info.
					if ( ! empty( $requested_file ) && strpos( $match, $requested_file ) === 0 && $requested_file != $requested_path ) {
						$request_match = $requested_file . '/' . $requested_path;
					}

					if ( preg_match( "#^$match#", $request_match, $matches ) ||
						preg_match( "#^$match#", urldecode( $request_match ), $matches ) ) {

						if ( $wp_rewrite->use_verbose_page_rules && preg_match( '/pagename=\$matches\[([0-9]+)\]/', $query, $varmatch ) ) {
							// This is a verbose page match, let's check to be sure about it.
							$page = get_page_by_path( $matches[ $varmatch[1] ] );
							if ( ! $page ) {
								continue;
							}

							$post_status_obj = get_post_status_object( $page->post_status );
							if ( ! $post_status_obj->public && ! $post_status_obj->protected
								&& ! $post_status_obj->private && $post_status_obj->exclude_from_search ) {
								continue;
							}
						}

						// Got a match.
						$this->matched_rule = $match;
						break;
					}
				}
			}

			if ( isset( $this->matched_rule ) ) {
				// Trim the query of everything up to the '?'.
				$query = preg_replace( '!^.+\?!', '', $query );

				// Substitute the substring matches into the query.
				$query = addslashes( WP_MatchesMapRegex::apply( $query, $matches ) );

				$this->matched_query = $query;

				// Parse the query.
				parse_str( $query, $perma_query_vars );

				// If we're processing a 404 request, clear the error var since we found something.
				if ( '404' == $error ) {
					unset( $error, $_GET['error'] );
				}
			}

			// If req_uri is empty or if it is a request for ourself, unset error.
			if ( empty( $requested_path ) || $requested_file == $self || strpos( $_SERVER['PHP_SELF'], 'wp-admin/' ) !== false ) {
				unset( $error, $_GET['error'] );

				if ( isset( $perma_query_vars ) && strpos( $_SERVER['PHP_SELF'], 'wp-admin/' ) !== false ) {
					unset( $perma_query_vars );
				}

				$this->did_permalink = false;
			}
		}

		/**
		 * Filters the query variables allowed before processing.
		 *
		 * Allows (publicly allowed) query vars to be added, removed, or changed prior
		 * to executing the query. Needed to allow custom rewrite rules using your own arguments
		 * to work, or any other custom query variables you want to be publicly available.
		 *
		 * @since 1.5.0
		 *
		 * @param string[] $public_query_vars The array of allowed query variable names.
		 */
		$this->public_query_vars = apply_filters( 'query_vars', $this->public_query_vars );

		foreach ( get_post_types( array(), 'objects' ) as $post_type => $t ) {
			if ( is_post_type_viewable( $t ) && $t->query_var ) {
				$post_type_query_vars[ $t->query_var ] = $post_type;
			}
		}

		foreach ( $this->public_query_vars as $wpvar ) {
			if ( isset( $this->extra_query_vars[ $wpvar ] ) ) {
				$this->query_vars[ $wpvar ] = $this->extra_query_vars[ $wpvar ];
			} elseif ( isset( $_GET[ $wpvar ] ) && isset( $_POST[ $wpvar ] ) && $_GET[ $wpvar ] !== $_POST[ $wpvar ] ) {
				wp_die( __( 'A variable mismatch has been detected.' ), __( 'Sorry, you are not allowed to view this item.' ), 400 );
			} elseif ( isset( $_POST[ $wpvar ] ) ) {
				$this->query_vars[ $wpvar ] = $_POST[ $wpvar ];
			} elseif ( isset( $_GET[ $wpvar ] ) ) {
				$this->query_vars[ $wpvar ] = $_GET[ $wpvar ];
			} elseif ( isset( $perma_query_vars[ $wpvar ] ) ) {
				$this->query_vars[ $wpvar ] = $perma_query_vars[ $wpvar ];
			}

			if ( ! empty( $this->query_vars[ $wpvar ] ) ) {
				if ( ! is_array( $this->query_vars[ $wpvar ] ) ) {
					$this->query_vars[ $wpvar ] = (string) $this->query_vars[ $wpvar ];
				} else {
					foreach ( $this->query_vars[ $wpvar ] as $vkey => $v ) {
						if ( is_scalar( $v ) ) {
							$this->query_vars[ $wpvar ][ $vkey ] = (string) $v;
						}
					}
				}

				if ( isset( $post_type_query_vars[ $wpvar ] ) ) {
					$this->query_vars['post_type'] = $post_type_query_vars[ $wpvar ];
					$this->query_vars['name']      = $this->query_vars[ $wpvar ];
				}
			}
		}

		// Convert urldecoded spaces back into '+'.
		foreach ( get_taxonomies( array(), 'objects' ) as $taxonomy => $t ) {
			if ( $t->query_var && isset( $this->query_vars[ $t->query_var ] ) ) {
				$this->query_vars[ $t->query_var ] = str_replace( ' ', '+', $this->query_vars[ $t->query_var ] );
			}
		}

		// Don't allow non-publicly queryable taxonomies to be queried from the front end.
		if ( ! is_admin() ) {
			foreach ( get_taxonomies( array( 'publicly_queryable' => false ), 'objects' ) as $taxonomy => $t ) {
				/*
				 * Disallow when set to the 'taxonomy' query var.
				 * Non-publicly queryable taxonomies cannot register custom query vars. See register_taxonomy().
				 */
				if ( isset( $this->query_vars['taxonomy'] ) && $taxonomy === $this->query_vars['taxonomy'] ) {
					unset( $this->query_vars['taxonomy'], $this->query_vars['term'] );
				}
			}
		}

		// Limit publicly queried post_types to those that are 'publicly_queryable'.
		if ( isset( $this->query_vars['post_type'] ) ) {
			$queryable_post_types = get_post_types( array( 'publicly_queryable' => true ) );
			if ( ! is_array( $this->query_vars['post_type'] ) ) {
				if ( ! in_array( $this->query_vars['post_type'], $queryable_post_types, true ) ) {
					unset( $this->query_vars['post_type'] );
				}
			} else {
				$this->query_vars['post_type'] = array_intersect( $this->query_vars['post_type'], $queryable_post_types );
			}
		}

		// Resolve conflicts between posts with numeric slugs and date archive queries.
		$this->query_vars = wp_resolve_numeric_slug_conflicts( $this->query_vars );

		foreach ( (array) $this->private_query_vars as $var ) {
			if ( isset( $this->extra_query_vars[ $var ] ) ) {
				$this->query_vars[ $var ] = $this->extra_query_vars[ $var ];
			}
		}

		if ( isset( $error ) ) {
			$this->query_vars['error'] = $error;
		}

		/**
		 * Filters the array of parsed query variables.
		 *
		 * @since 2.1.0
		 *
		 * @param array $query_vars The array of requested query variables.
		 */
		$this->query_vars = apply_filters( 'request', $this->query_vars );

		/**
		 * Fires once all query variables for the current request have been parsed.
		 *
		 * @since 2.1.0
		 *
		 * @param WP $this Current WordPress environment instance (passed by reference).
		 */
		do_action_ref_array( 'parse_request', array( &$this ) );
	}