(split-height-threshold, split-width-threshold): Add

choice nil.
(split-window-preferred-function): Allow either nil or a function.
(window--splittable-p, window--try-to-split-window): Handle
changed option values.
(window--frame-usable-p): Handle nil argument.
(display-buffer): Call get-lru-window when pop-up-windows is nil
and window can't be split.

2 files changed, 97 insertions, 75 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 3cef51e02d8..ae82adca289 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,16 @@
+2008-06-08  Martin Rudalics  <rudalics@gmx.at>
+
+        * window.el (split-height-threshold, split-width-threshold): Add
+        choice nil.
+        (split-window-preferred-function): Allow either nil or a function.
+        (window--splittable-p, window--try-to-split-window): Handle
+        changed option values.
+
+        (window--frame-usable-p): Handle nil argument.
+
+        (display-buffer): Call get-lru-window when pop-up-windows is nil
+        and window can't be split.
+
 2008-06-08  Michael Albinus  <michael.albinus@gmx.de>
 
         * uniquify.el (uniquify-get-proposed-name): Handle remote files.
diff --git a/lisp/window.el b/lisp/window.el
index 74bcdcdaef1..74c7a366f0f 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -544,19 +544,19 @@ would be used to make a frame for that buffer.  The variables
 `special-display-buffer-names' and `special-display-regexps'
 control this."
   (let (tmp)
-    (cond
-     ((not (stringp buffer-name)))
-     ;; Make sure to return t in the following two cases.
-     ((member buffer-name special-display-buffer-names) t)
+  (cond
+   ((not (stringp buffer-name)))
+   ;; Make sure to return t in the following two cases.
+   ((member buffer-name special-display-buffer-names) t)
      ((setq tmp (assoc buffer-name special-display-buffer-names)) (cdr tmp))
-     ((catch 'found
-        (dolist (regexp special-display-regexps)
-          (cond
-           ((stringp regexp)
-            (when (string-match-p regexp buffer-name)
-              (throw 'found t)))
-           ((and (consp regexp) (stringp (car regexp))
-                 (string-match-p (car regexp) buffer-name))
+   ((catch 'found
+      (dolist (regexp special-display-regexps)
+        (cond
+         ((stringp regexp)
+          (when (string-match-p regexp buffer-name)
+            (throw 'found t)))
+         ((and (consp regexp) (stringp (car regexp))
+               (string-match-p (car regexp) buffer-name))
             (throw 'found (cdr regexp))))))))))
 
 (defcustom special-display-buffer-names nil
@@ -742,32 +742,37 @@ parameters."
   :type 'boolean
   :group 'windows)
 
-(defcustom split-window-preferred-function nil
-  "How `display-buffer' shall split windows.
-Choices are `Vertically', `Horizontally', and `Sensibly' where
-the latter attempts to split wide windows horizontally, narrow
-ones vertically.  Alternatively, you can set this to a function
-called with a window as single argument to split that window in
-two and return the new window."
-  :type '(choice
-          (const :tag "Vertically" nil)
-          (const :tag "Horizontally" horizontally)
-          (const :tag "Sensibly" sensibly)
-          (function :tag "Function"))
-  :version "23.1"
-  :group 'windows)
-
 (defcustom split-height-threshold 80
-  "Minimum height of window to be split vertically by `display-buffer'.
-If there is only one window, it can be split regardless of this."
+  "Minimum height of window to be split vertically.
+If the value is a number, `display-buffer' can split a window
+only if it has at least as many lines.  If the value is nil,
+`display-buffer' cannot split a window vertically.
+
+If the window is the only window on its frame, `display-buffer'
+can split it regardless of this value."
+  :type '(choice (const nil) (number :tag "lines"))
   :type 'number
   :version "23.1"
   :group 'windows)
 
 (defcustom split-width-threshold 160
-  "Minimum width of window to be split horizontally by `display-buffer'.
-If there is only one window, it can be split regardless of this."
-  :type 'number
+  "Minimum width of window to be split horizontally.
+If the value is a number, `display-buffer' can split a window
+only if it has at least as many columns.  If the value is nil,
+`display-buffer' cannot split a window horizontally."
+  :type '(choice (const nil) (number :tag "columns"))
+  :version "23.1"
+  :group 'windows)
+
+(defcustom split-window-preferred-function nil
+  "Function used by `display-buffer' to split windows.
+If non-nil, a function called with a window as single argument
+supposed to split that window and return the new window.  If the
+function returns nil the window is not split.
+
+If nil, `display-buffer' will split the window respecting the
+values of `split-height-threshold' and `split-width-threshold'."
+  :type '(choice (const nil) (function :tag "Function"))
   :version "23.1"
   :group 'windows)
 
@@ -779,11 +784,11 @@ can be split horizontally.
 WINDOW can be split vertically when the following conditions
 hold:
 
-- `window-size-fixed' is either nil or equals `width' for the buffer of
-  WINDOW.
+- `window-size-fixed' is either nil or equals `width' for the
+  buffer of WINDOW.
 
-- WINDOW is at least as high as `split-height-threshold' or it is
-  the only window on its frame.
+- `split-height-threshold' is a number and WINDOW is at least as
+  high as `split-height-threshold'.
 
 - When WINDOW is split evenly, the emanating windows are at least
   `window-min-height' lines tall and can accomodate at least one
@@ -795,7 +800,8 @@ hold:
 - `window-size-fixed' is either nil or equals `height' for the
   buffer of WINDOW.
 
-- WINDOW is at least as wide as `split-width-threshold'.
+- `split-width-threshold' is a number and WINDOW is at least as
+  wide as `split-width-threshold'.
 
 - When WINDOW is split evenly, the emanating windows are at least
   `window-min-width' or two (whichever is larger) columns wide."
@@ -807,57 +813,60 @@ hold:
           ;; and at least twice as wide as `window-min-width' and 2 (the
           ;; latter value is hardcoded).
           (and (memq window-size-fixed '(nil height))
+               ;; Testing `window-full-width-p' here hardly makes any
+               ;; sense nowadays.  This can be done more intuitively by
+               ;; setting up `split-width-threshold' appropriately.
+               (numberp split-width-threshold)
                (>= (window-width window)
                    (max split-width-threshold
                         (* 2 (max window-min-width 2)))))
         ;; A window can be split vertically when its height is not
-        ;; fixed, it is at least `split-height-threshold' lines high or
-        ;; the only window on its frame, and it is at least twice as
-        ;; high as `window-min-height' and 2 if it has a modeline or 1.
+        ;; fixed, it is at least `split-height-threshold' lines high,
+        ;; and it is at least twice as high as `window-min-height' and 2
+        ;; if it has a modeline or 1.
         (and (memq window-size-fixed '(nil width))
+             (numberp split-height-threshold)
              (>= (window-height window)
-                 (max (if (one-window-p 'nomini) 0 split-height-threshold)
+                 (max split-height-threshold
                       (* 2 (max window-min-height
                                 (if mode-line-format 2 1))))))))))
 
 (defun window--try-to-split-window (window)
   "Split window WINDOW if it is splittable.
-See `split-window-preferred-function' for how WINDOW shall be
-split.  See `window--splittable-p' for how to determine whether a
-window is splittable.  If WINDOW can be split, return the value
-returned by `split-window' or `split-window-preferred-function'."
+See `window--splittable-p' for how to determine whether a window
+is splittable.  If WINDOW can be split, return the value returned
+by `split-window' or `split-window-preferred-function'."
   (when (and (window-live-p window)
-             ;; Testing `window-full-width-p' here hardly makes any
-             ;; sense nowadays.  This can be done more intuitively by
-             ;; setting up `split-width-threshold' appropriately.
              (not (frame-parameter (window-frame window) 'unsplittable)))
-    (or (and (not split-window-preferred-function)
-             (window--splittable-p window)
-             (split-window window))
-        (and (eq split-window-preferred-function 'horizontally)
-             (window--splittable-p window t)
-             (split-window window nil t))
-        (and (eq split-window-preferred-function 'sensibly)
-             ;; The following naive aspect-ratio test should become
-             ;; more sensible.
-             (or (and (> (window-width window) (window-height window))
-                      (window--splittable-p window t)
-                      (split-window window nil t))
-                 (and (window--splittable-p window)
-                      (split-window window))))
-        (and (functionp split-window-preferred-function)
-             (funcall split-window-preferred-function window)))))
+    (if (functionp split-window-preferred-function)
+        ;; `split-window-preferred-function' is specified, so use it.
+        (funcall split-window-preferred-function window)
+      (or (and (window--splittable-p window)
+               ;; Split window vertically.
+               (split-window window))
+          (and (window--splittable-p window t)
+               ;; Split window horizontally.
+               (split-window window nil t))
+          (and (with-selected-window window
+                 (one-window-p 'nomini))
+               ;; If WINDOW is the only window on its frame, attempt to
+               ;; split it vertically disregarding the current value of
+               ;; `split-height-threshold'.
+               (let ((split-height-threshold 0))
+                 (window--splittable-p window)
+                 (split-window window)))))))
 
 (defun window--frame-usable-p (frame)
   "Return frame FRAME if it can be used to display another buffer."
-  (let ((window (frame-root-window frame)))
-    ;; `frame-root-window' may be an internal window which is considered
-    ;; "dead" by `window-live-p'.  Hence if `window' is not live we
-    ;; implicitly know that `frame' has a visible window we can use.
-    (when (or (not (window-live-p window))
-              (and (not (window-minibuffer-p window))
-                   (not (window-dedicated-p window))))
-      frame)))
+  (when (framep frame)
+    (let ((window (frame-root-window frame)))
+      ;; `frame-root-window' may be an internal window which is considered
+      ;; "dead" by `window-live-p'.  Hence if `window' is not live we
+      ;; implicitly know that `frame' has a visible window we can use.
+      (when (or (not (window-live-p window))
+                (and (not (window-minibuffer-p window))
+                     (not (window-dedicated-p window))))
+        frame))))
 
 (defcustom even-window-heights t
   "If non-nil `display-buffer' will try to even window heights.
@@ -1009,12 +1018,12 @@ consider all visible or iconified frames."
                  (or (window--try-to-split-window
                       (get-largest-window frame-to-use t))
                      (window--try-to-split-window
-                      (get-lru-window frame-to-use t))
-                     (get-lru-window frame-to-use nil)))
+                      (get-lru-window frame-to-use t))))
            (window--display-buffer-2 buffer window-to-use)))
      ((setq window-to-use
             ;; Reuse an existing window.
-            (or (get-buffer-window buffer 'visible)
+            (or (get-lru-window frame-to-use)
+                (get-buffer-window buffer 'visible)
                 (get-largest-window 'visible nil)
                 (get-buffer-window buffer 0)
                 (get-largest-window 0 nil)