emacs: Introduce `notmuch-call-notmuch-sexp'

This is just like `notmuch-call-notmuch-json', but parses S-expression
output.  Note that, also like `notmuch-call-notmuch-json', this
doesn't consider trailing data to be an error, which may or may not be
what we want in the long run.

1 files changed, 17 insertions, 0 deletions

diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el
index 79a1290d..c82c6c2a 100644
--- a/emacs/notmuch-lib.el
+++ b/emacs/notmuch-lib.el
@@ -489,6 +489,23 @@ an error."
 	      (json-read)))
 	(delete-file err-file)))))
 
+(defun notmuch-call-notmuch-sexp (&rest args)
+  "Invoke `notmuch-command' with ARGS and return the parsed S-exp output.
+
+If notmuch exits with a non-zero status, this will pop up a
+buffer containing notmuch's output and signal an error."
+
+  (with-temp-buffer
+    (let ((err-file (make-temp-file "nmerr")))
+      (unwind-protect
+	  (let ((status (apply #'call-process
+			       notmuch-command nil (list t err-file) nil args)))
+	    (notmuch-check-exit-status status (cons notmuch-command args)
+				       (buffer-string) err-file)
+	    (goto-char (point-min))
+	    (read (current-buffer)))
+	(delete-file err-file)))))
+
 (defun notmuch-start-notmuch (name buffer sentinel &rest args)
   "Start and return an asynchronous notmuch command.