* lisp/shell.el (shell-dir-cookie-re): New custom variable.

(shell-dir-cookie-watcher): New function.

1 files changed, 29 insertions, 0 deletions

diff --git a/lisp/shell.el b/lisp/shell.el
index 75040305528..7771c0d1c4f 100644
--- a/lisp/shell.el
+++ b/lisp/shell.el
@@ -472,6 +472,10 @@ buffer."
       (when (string-equal shell "bash")
         (add-hook 'comint-output-filter-functions
                   'shell-filter-ctrl-a-ctrl-b nil t)))
+    (when shell-dir-cookie-re
+      ;; Watch for magic cookies in the output to track the current dir.
+      (add-hook 'comint-output-filter-functions
+		'shell-dir-cookie-watcher nil t))
     (comint-read-input-ring t)))
 
 (defun shell-filter-ctrl-a-ctrl-b (string)
@@ -619,6 +623,31 @@ Otherwise, one argument `-i' is passed to the shell.
 ;; replace it with a process filter that watches for and strips out
 ;; these messages.
 
+(defcustom shell-dir-cookie-re nil
+  "Regexp matching your prompt, including some part of the current directory.
+If your prompt includes the current directory or the last few elements of it,
+set this to a pattern that matches your prompt and whose subgroup 1 matches
+the directory part of it.
+This is used by `shell-dir-cookie-watcher' to try and use this info
+to track your current directory.  It can be used instead of or in addition
+to `dirtrack-mode'."
+  :type '(choice (const nil) regexp))
+
+(defun shell-dir-cookie-watcher (text)
+  ;; This is fragile: the TEXT could be split into several chunks and we'd
+  ;; miss it.  Oh well.  It's a best effort anyway.  I'd expect that it's
+  ;; rather unusual to have the prompt split into several packets, but
+  ;; I'm sure Murphy will prove me wrong.
+  (when (and shell-dir-cookie-re (string-match shell-dir-cookie-re text))
+    (let ((dir (match-string 1 text)))
+      (cond
+       ((file-name-absolute-p dir) (shell-cd dir))
+       ;; Let's try and see if it seems to be up or down from where we were.
+       ((string-match "\\`\\(.*\\)\\(?:/.*\\)?\n\\(.*/\\)\\1\\(?:/.*\\)?\\'"
+		      (setq text (concat dir "\n" default-directory)))
+	(shell-cd (concat (match-string 2 text) dir)))))))
+	
+
 (defun shell-directory-tracker (str)
   "Tracks cd, pushd and popd commands issued to the shell.
 This function is called on each input passed to the shell.