From e19243329cc15f2a4ba1a3e53934b7041187e30c Mon Sep 17 00:00:00 2001
From: Robby Findler <robby@racket-lang.org>
Date: Mon, 17 Dec 2012 09:09:56 -0600
Subject: [PATCH] adjust drracket to track an lru order on tabs and use it when
 closing one to pick the next one to show

added the touched and get-last-touched methods to tab<%>
---
 collects/drracket/private/unit.rkt    | 18 ++++++++++++++----
 collects/scribblings/tools/unit.scrbl | 17 ++++++++++++++++-
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/collects/drracket/private/unit.rkt b/collects/drracket/private/unit.rkt
index 2378b14bd5..62b1974c44 100644
--- a/collects/drracket/private/unit.rkt
+++ b/collects/drracket/private/unit.rkt
@@ -1215,6 +1215,10 @@ module browser threading seems wrong.
         (send frame enable-evaluation-in-tab this))
       (define/public (get-enabled) enabled?)
       
+      (define last-touched (current-inexact-milliseconds))
+      (define/public-final (touched) (set! last-touched (current-inexact-milliseconds)))
+      (define/public-final (get-last-touched) last-touched)
+      
       ;; current-execute-warning is a snapshot of the needs-execution-message
       ;; that is taken each time repl submission happens, and it gets reset
       ;; when "Run" is clicked.
@@ -2946,6 +2950,8 @@ module browser threading seems wrong.
             
             (send definitions-text update-frame-filename)
             (update-running (send current-tab is-running?))
+            (when (eq? this (get-top-level-focus-window))
+              (send current-tab touched))
             (on-tab-change old-tab current-tab)
             (send tab update-log)
             (send tab update-planet-status)
@@ -2991,10 +2997,9 @@ module browser threading seems wrong.
                         (set! tabs (remq tab tabs))
                         (send tabs-panel delete (send tab get-i))
                         (update-menu-bindings) 
-                        (change-to-tab (cond
-                                         [(< (send tab get-i) (length tabs))
-                                          (list-ref tabs (send tab get-i))]
-                                         [else (last tabs)])))
+                        (change-to-tab
+                         (argmax (λ (tab) (send tab get-last-touched)) 
+                                 tabs)))
                       (loop (cdr l-tabs))))]))]))
       
       ;; a helper private method for close-current-tab -- doesn't close an arbitrary tab.
@@ -3134,6 +3139,11 @@ module browser threading seems wrong.
               [else (super restore-keybinding)]))
           (super-new)))
       
+      (define/override (on-activate active?)
+        (when active?
+          (send (get-current-tab) touched))
+        (super on-activate active?))
+      
       (define/private (update-menu-bindings)
         (when close-tab-menu-item
           (update-close-tab-menu-item-shortcut close-tab-menu-item))
diff --git a/collects/scribblings/tools/unit.scrbl b/collects/scribblings/tools/unit.scrbl
index c1b326ab01..7528afcf12 100644
--- a/collects/scribblings/tools/unit.scrbl
+++ b/collects/scribblings/tools/unit.scrbl
@@ -155,7 +155,22 @@ Calls the definitions text's
 
    See also @method[drracket:unit:tab<%> add-bkg-running-color].
   }
-
+@defmethod[#:mode public-final (touched) void?]{
+  Called by the system to indicate that the tab has
+  just been switched to from another tab in the 
+  same frame (when the frame has the focus) 
+  or the frame itself has come to the 
+  front (via @method[top-level-window<%> on-activate])
+  and the tab is the current tab in that frame.
+ 
+  This method updates the private state that
+  @method[drracket:unit:tab<%> get-last-touched]
+  returns.
+  }
+@defmethod[#:mode public-final (get-last-touched) flonum?]{
+   Returns the time that this tab was last focused, as counted
+   by @racket[current-inexact-milliseconds].
+ }
 }