emacs: Introduce notmuch-jump: shortcut keys to saved searches

This introduces notmuch-jump, which is like a user-friendly,
user-configurable global prefix map for saved searches.  This provides
a non-modal and much faster way to access saved searches than
notmuch-hello.

A user configures shortcut keys in notmuch-saved-searches, which are
immediately accessible from anywhere in Notmuch under the "j" key (for
"jump").  When the user hits "j", the minibuffer immediately shows a
helpful table of bindings reminiscent of a completions buffer.

This code is a combination of work from myself (originally,
"notmuch-go"), David Edmondson, and modifications from Mark Walters.

4 files changed, 190 insertions, 1 deletions

diff --git a/emacs/Makefile.local b/emacs/Makefile.local
index c0d6b190..1109cfa6 100644
--- a/emacs/Makefile.local
+++ b/emacs/Makefile.local
@@ -18,7 +18,8 @@ emacs_sources := \
 	$(dir)/notmuch-tag.el \
 	$(dir)/coolj.el \
 	$(dir)/notmuch-print.el \
-	$(dir)/notmuch-version.el
+	$(dir)/notmuch-version.el \
+	$(dir)/notmuch-jump.el \
 
 $(dir)/notmuch-version.el: $(dir)/Makefile.local version.stamp
 $(dir)/notmuch-version.el: $(srcdir)/$(dir)/notmuch-version.el.tmpl
diff --git a/emacs/notmuch-hello.el b/emacs/notmuch-hello.el
index 3de52386..061b27d0 100644
--- a/emacs/notmuch-hello.el
+++ b/emacs/notmuch-hello.el
@@ -85,6 +85,7 @@ searches so they still work in customize."
 		(group :format "%v" :inline t (const :format "  Query: " :query) (string :format "%v")))
 	  (checklist :inline t
 		     :format "%v"
+		     (group :format "%v" :inline t (const :format "Shortcut key: " :key) (key-sequence :format "%v"))
 		     (group :format "%v" :inline t (const :format "Count-Query: " :count-query) (string :format "%v"))
 		     (group :format "%v" :inline t (const :format "" :sort-order)
 			    (choice :tag " Sort Order"
@@ -101,6 +102,7 @@ a plist. Supported properties are
 
   :name            Name of the search (required).
   :query           Search to run (required).
+  :key             Optional shortcut key for `notmuch-jump-search'.
   :count-query     Optional extra query to generate the count
                    shown. If not present then the :query property
                    is used.
diff --git a/emacs/notmuch-jump.el b/emacs/notmuch-jump.el
new file mode 100644
index 00000000..05bbce5e
--- /dev/null
+++ b/emacs/notmuch-jump.el
@@ -0,0 +1,173 @@
+;; notmuch-jump.el --- User-friendly shortcut keys
+;;
+;; Copyright © Austin Clements
+;;
+;; This file is part of Notmuch.
+;;
+;; Notmuch is free software: you can redistribute it and/or modify it
+;; under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; Notmuch is distributed in the hope that it will be useful, but
+;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;; General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with Notmuch.  If not, see <http://www.gnu.org/licenses/>.
+;;
+;; Authors: Austin Clements <aclements@csail.mit.edu>
+;;          David Edmondson <dme@dme.org>
+
+(eval-when-compile (require 'cl))
+
+(require 'notmuch-lib)
+(require 'notmuch-hello)
+
+;;;###autoload
+(defun notmuch-jump-search ()
+  "Jump to a saved search by shortcut key.
+
+This prompts for and performs a saved search using the shortcut
+keys configured in the :key property of `notmuch-saved-searches'.
+Typically these shortcuts are a single key long, so this is a
+fast way to jump to a saved search from anywhere in Notmuch."
+  (interactive)
+
+  ;; Build the action map
+  (let (action-map)
+    (dolist (saved-search notmuch-saved-searches)
+      (let* ((saved-search (notmuch-hello-saved-search-to-plist saved-search))
+	     (key (plist-get saved-search :key)))
+	(when key
+	  (let ((name (plist-get saved-search :name))
+		(query (plist-get saved-search :query))
+		(oldest-first
+		 (case (plist-get saved-search :sort-order)
+		   (newest-first nil)
+		   (oldest-first t)
+		   (otherwise (default-value notmuch-search-oldest-first)))))
+	    (push (list key name
+			`(lambda () (notmuch-search ',query ',oldest-first)))
+		  action-map)))))
+    (setq action-map (nreverse action-map))
+
+    (if action-map
+	(notmuch-jump action-map "Search: ")
+      (error "To use notmuch-jump, please customize shortcut keys in notmuch-saved-searches."))))
+
+(defvar notmuch-jump--action nil)
+
+(defun notmuch-jump (action-map prompt)
+  "Interactively prompt for one of the keys in ACTION-MAP.
+
+Displays a summary of all bindings in ACTION-MAP in the
+minibuffer, reads a key from the minibuffer, and performs the
+corresponding action.  The prompt can be canceled with C-g or
+RET.  PROMPT must be a string to use for the prompt.  PROMPT
+should include a space at the end.
+
+ACTION-MAP must be a list of triples of the form
+  (KEY LABEL ACTION)
+where KEY is a key binding, LABEL is a string label to display in
+the buffer, and ACTION is a nullary function to call.  LABEL may
+be null, in which case the action will still be bound, but will
+not appear in the pop-up buffer.
+"
+
+  (let* ((items (notmuch-jump--format-actions action-map))
+	 ;; Format the table of bindings and the full prompt
+	 (table
+	  (with-temp-buffer
+	    (notmuch-jump--insert-items (window-body-width) items)
+	    (buffer-string)))
+	 (full-prompt
+	  (concat table "\n\n"
+		  (propertize prompt 'face 'minibuffer-prompt)))
+	 ;; By default, the minibuffer applies the minibuffer face to
+	 ;; the entire prompt.  However, we want to clearly
+	 ;; distinguish bindings (which we put in the prompt face
+	 ;; ourselves) from their labels, so disable the minibuffer's
+	 ;; own re-face-ing.
+	 (minibuffer-prompt-properties
+	  (notmuch-plist-delete
+	   (copy-sequence minibuffer-prompt-properties)
+	   'face))
+	 ;; Build the keymap with our bindings
+	 (minibuffer-map (notmuch-jump--make-keymap action-map))
+	 ;; The bindings save the the action in notmuch-jump--action
+	 (notmuch-jump--action nil))
+    ;; Read the action
+    (read-from-minibuffer full-prompt nil minibuffer-map)
+
+    ;; If we got an action, do it
+    (when notmuch-jump--action
+      (funcall notmuch-jump--action))))
+
+(defun notmuch-jump--format-actions (action-map)
+  "Format the actions in ACTION-MAP.
+
+Returns a list of strings, one for each item with a label in
+ACTION-MAP.  These strings can be inserted into a tabular
+buffer."
+
+  ;; Compute the maximum key description width
+  (let ((key-width 1))
+    (dolist (entry action-map)
+      (setq key-width
+	    (max key-width
+		 (string-width (format-kbd-macro (first entry))))))
+    ;; Format each action
+    (mapcar (lambda (entry)
+	      (let ((key (format-kbd-macro (first entry)))
+		    (desc (second entry)))
+		(concat
+		 (propertize key 'face 'minibuffer-prompt)
+		 (make-string (- key-width (length key)) ? )
+		 " " desc)))
+	    action-map)))
+
+(defun notmuch-jump--insert-items (width items)
+  "Make a table of ITEMS up to WIDTH wide in the current buffer."
+  (let* ((nitems (length items))
+	 (col-width (+ 3 (apply #'max (mapcar #'string-width items))))
+	 (ncols (if (> (* col-width nitems) width)
+		    (max 1 (/ width col-width))
+		  ;; Items fit on one line.  Space them out
+		  (setq col-width (/ width nitems))
+		  (length items))))
+    (while items
+      (dotimes (col ncols)
+	(when items
+	  (let ((item (pop items)))
+	    (insert item)
+	    (when (and items (< col (- ncols 1)))
+	      (insert (make-string (- col-width (string-width item)) ? ))))))
+      (when items
+	(insert "\n")))))
+
+(defvar notmuch-jump-minibuffer-map
+  (let ((map (make-sparse-keymap)))
+    (set-keymap-parent map minibuffer-local-map)
+    ;; Make this like a special-mode keymap, with no self-insert-command
+    (suppress-keymap map)
+    map)
+  "Base keymap for notmuch-jump's minibuffer keymap.")
+
+(defun notmuch-jump--make-keymap (action-map)
+  "Translate ACTION-MAP into a minibuffer keymap."
+  (let ((map (make-sparse-keymap)))
+    (set-keymap-parent map notmuch-jump-minibuffer-map)
+    (dolist (action action-map)
+      (define-key map (first action)
+	`(lambda () (interactive)
+	   (setq notmuch-jump--action ',(third action))
+	   (exit-minibuffer))))
+    map))
+
+(unless (fboundp 'window-body-width)
+  ;; Compatibility for Emacs pre-24
+  (defun window-body-width (&optional window)
+    (let ((edges (window-inside-edges window)))
+      (- (caddr edges) (car edges)))))
diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el
index c06baac0..19269e3c 100644
--- a/emacs/notmuch-lib.el
+++ b/emacs/notmuch-lib.el
@@ -25,6 +25,9 @@
 (require 'mm-decode)
 (require 'cl)
 
+(autoload 'notmuch-jump-search "notmuch-jump"
+  "Jump to a saved search by shortcut key." t)
+
 (defgroup notmuch nil
   "Notmuch mail reader for Emacs."
   :group 'mail)
@@ -138,6 +141,7 @@ For example, if you wanted to remove an \"inbox\" tag and add an
     (define-key map "m" 'notmuch-mua-new-mail)
     (define-key map "=" 'notmuch-refresh-this-buffer)
     (define-key map "G" 'notmuch-poll-and-refresh-this-buffer)
+    (define-key map "j" 'notmuch-jump-search)
     map)
   "Keymap shared by all notmuch modes.")
 
@@ -472,6 +476,15 @@ This replaces spaces, percents, and double quotes in STR with
       (setq list (cdr list)))
     (nreverse out)))
 
+(defun notmuch-plist-delete (plist property)
+  (let* ((xplist (cons nil plist))
+	 (pred xplist))
+    (while (cdr pred)
+      (when (eq (cadr pred) property)
+	(setcdr pred (cdddr pred)))
+      (setq pred (cddr pred)))
+    (cdr xplist)))
+
 (defun notmuch-split-content-type (content-type)
   "Split content/type into 'content' and 'type'"
   (split-string content-type "/"))