mu4e/server: get cached list of labels

This will be useful with label commands.

lib/mu-server.cc

@@ -551,19 +551,35 @@ Server::Private::contacts_handler(const Command& cmd)
 	mu_debug("sent {} of {} contact(s)", n, store().contacts_cache().size());
 }
 
+template<typename T, typename F>
+std::string quoted_join(const T& items, F&& func)
+{
+	std::vector<std::string> vec;
+
+	std::transform(items.begin(), items.end(), std::back_inserter(vec),
+		       [&](const auto& item) { return quote(func(item)); });
+
+	return join(vec,  " ");
+}
+
 void
 Server::Private::data_handler(const Command& cmd)
 {
 	const auto request_type{unwrap(cmd.symbol_arg(":kind"))};
 
-	if (request_type == "maildirs") {
-		auto&& out{make_output_stream()};
-		mu_print(out, "(");
-		for (auto&& mdir: store().maildirs())
-			mu_println(out, "{}", quote(std::move(mdir)));
-		mu_print(out, ")");
-		output(mu_format("(:maildirs {})", out.to_string()));
-	} else
+	if (request_type == "maildirs")
+		output(mu_format("(:maildirs ({}))",
+				 quoted_join(store().maildirs(),
+					     [](const auto& item) {
+					     return item; // identity
+					     })));
+	else if (request_type == "labels")
+		output(mu_format("(:labels ({}))",
+				 quoted_join(store().label_map(),
+					     [](const auto& item) {
+						     return item.first;
+					     })));
+	else
 		throw Error(Error::Code::InvalidArgument,
 			"invalid request type '{}'", request_type);
 }

mu4e/mu4e-search.el

@@ -154,6 +154,9 @@ but also manually invoked searches."
   :type 'hook
   :group 'mu4e-search)
 
+(defvar mu4e-labels-list nil
+  "Cached list of labels.")
+
 ;; Internals
 
 ;;; History

mu4e/mu4e-server.el

@@ -130,6 +130,7 @@ Note: this REPL is not to be confused with the mu REPL as per
 
 ;; Cached data
 (defvar mu4e-maildir-list)
+(defvar mu4e-labels-list)
 
 ;; Handlers are not strictly internal, but are not meant
 ;; for overriding outside mu4e. The are mainly for breaking
@@ -470,6 +471,8 @@ The server output is as follows:
          ;; get some data
          ((plist-get sexp :maildirs)
           (setq mu4e-maildir-list (mu4e--server-plist-get sexp :maildirs)))
+         ((plist-get sexp :labels)
+          (setq mu4e-labels-list (mu4e--server-plist-get sexp :labels)))
 
          ;; receive an error
          ((plist-get sexp :error)
@@ -654,7 +657,7 @@ get at most MAX contacts."
 
 (defun mu4e--server-data (kind)
   "Request data of some KIND.
-KIND is a symbol. Currently supported kinds: maildirs."
+KIND is a symbol. One of maildirs, labels."
   (mu4e--server-call-mu
    `(data :kind ,kind)))
 

mu4e/mu4e.el

@@ -160,8 +160,9 @@ invoke FUNC (if available) afterwards."
   (add-hook 'mu4e-query-items-updated-hook #'mu4e--main-redraw)
   (setq mu4e--initialized t) ;; last before we call the server.
   (mu4e--server-ping)
-  ;; ask for the maildir-list
+  ;; ask for the maildir-list and labels
   (mu4e--server-data 'maildirs)
+  (mu4e--server-data 'labels)
   ;; maybe request the list of contacts, automatically refreshed after
   ;; re-indexing
   (mu4e--query-items-refresh 'reset-baseline)
@@ -249,7 +250,9 @@ invoke FUNC (if available) afterwards."
           (unless (and (not (string= mu4e--contacts-tstamp "0"))
                        (zerop (plist-get info :updated)))
             (mu4e--request-contacts-maybe)
-            (mu4e--server-data 'maildirs)) ;; update maildir list
+            (mu4e--server-data 'maildirs)
+            (mu4e--server-data 'labels)) ;; update maildir/labels list
+
           (mu4e--main-redraw))))
      ((plist-get info :message)
       (mu4e-index-message "%s" (plist-get info :message))))))