Simplify connection tracking code

Might affect #1266 and #1263.

`cider-find-connection-buffer-for-project-directory` embraces
ambiguities instead of avoiding them. By returning the first of multiple
matching buffers, it plays nice with the sibling connections.
It also returns buffers with nil directories if nothing else matches,
but this is just to try to fail as little as possible, it has nothing to
do with siblings.

`cider-switch-to-relevant-repl-buffer` just calls
`cider-current-repl-buffer` directly. This allows it to work in sibling
connections without complaining.

1 files changed, 26 insertions, 34 deletions

diff --git a/cider-interaction.el b/cider-interaction.el
index f26c2043..3414e05e 100644
--- a/cider-interaction.el
+++ b/cider-interaction.el
@@ -507,28 +507,28 @@ that of the namespace in the Clojure source buffer."
 (defun cider-find-connection-buffer-for-project-directory (project-directory)
   "Find the relevant connection-buffer for the given PROJECT-DIRECTORY.
 
-A check is made to ensure that all connection buffers have a project-directory
-otherwise there is ambiguity as to which connection buffer should be selected.
-
-If there are multiple connection buffers matching PROJECT-DIRECTORY there
-is ambiguity, therefore nil is returned."
-  (unless (-filter
-           (lambda (conn)
-             (not
+If there are multiple connection buffers matching PROJECT-DIRECTORY the
+most recent one is returned.
+If no buffers match PROJECT-DIRECTORY but there are buffers with no
+associated directory, the most recent one of those is returned.
+
+Here, \"most recent\" stands for the connection closer to the start of
+`cider-connections'.
+This is usally the connection that was more recently prepended to this
+variable, but the order can be changed.  For instance, the function
+`cider-make-connection-default' can be used to move a connection to the
+head of the list, so that it will take precedence over other connections
+associated with the same project."
+(or (-first (lambda (conn)
+              (-when-let (conn-proj-dir (with-current-buffer (get-buffer conn)
+                                          nrepl-project-dir))
+                (equal (file-truename project-directory)
+                       (file-truename conn-proj-dir))))
+            cider-connections)
+    (-first (lambda (conn)
               (with-current-buffer (get-buffer conn)
-                nrepl-project-dir)))
-           cider-connections)
-    (let ((matching-connections
-           (-filter
-            (lambda (conn)
-              (let ((conn-proj-dir (with-current-buffer (get-buffer conn)
-                                     nrepl-project-dir)))
-                (when conn-proj-dir
-                  (equal (file-truename project-directory)
-                         (file-truename conn-proj-dir)))))
+                (not nrepl-project-dir)))
             cider-connections)))
-      (when (= 1 (length matching-connections))
-        (car matching-connections)))))
 
 (defun cider-assoc-project-with-connection (&optional project connection)
   "Associate a Clojure PROJECT with an nREPL CONNECTION.
@@ -563,17 +563,14 @@ such a link cannot be established automatically."
 (defun cider-find-relevant-connection ()
   "Try to find the matching REPL buffer for the current Clojure source buffer.
 If succesful, return the new connection buffer."
-  (interactive "P")
   (cider-ensure-connected)
   (if cider-buffer-connection
       cider-buffer-connection
-    (let* ((project-directory (clojure-project-dir (cider-current-dir)))
-           (connection-buffer
-            (or
-             (and (= 1 (length cider-connections)) (car cider-connections))
-             (and project-directory
-                  (cider-find-connection-buffer-for-project-directory project-directory)))))
-      connection-buffer)))
+    (let* ((project-directory (clojure-project-dir (cider-current-dir))))
+      (or (and (= 1 (length cider-connections))
+               (car cider-connections))
+          (and project-directory
+               (cider-find-connection-buffer-for-project-directory project-directory))))))
 
 (defun cider-switch-to-relevant-repl-buffer (&optional set-namespace)
   "Select the REPL buffer, when possible in an existing window.
@@ -590,12 +587,7 @@ the buffer should appear.
 With a prefix arg SET-NAMESPACE sets the namespace in the REPL buffer to that
 of the namespace in the Clojure source buffer."
   (interactive "P")
-  (let ((connection-buffer (cider-find-relevant-connection)))
-    (if connection-buffer
-        (cider--switch-to-repl-buffer connection-buffer set-namespace)
-      (cider--switch-to-repl-buffer (cider-default-connection) set-namespace)
-      (message "Could not determine relevant nREPL connection, using: %s"
-               (cider--connection-info (cider-current-repl-buffer))))))
+  (cider--switch-to-repl-buffer (cider-current-repl-buffer) set-namespace))
 
 (defun cider-switch-to-last-clojure-buffer ()
   "Switch to the last Clojure buffer.