(any_kboard_state): Renamed from unlock_kboard.

Define it unconditionally, but it's a no-op unless MULTI_KBOARD.
(single_kboard_state): New function.
(push_frame_kboard, pop_frame_kboard): New functions.
(single_kboard): Renamed from kboard_locked.

(unlock_kboard): Do nothing with Vunread_command_events.
(read_char): Clean up logic for reading from KBOARD queues.

(kbd_buffer_get_event): Set copy by assignment, not init.

1 files changed, 123 insertions, 54 deletions

diff --git a/src/keyboard.c b/src/keyboard.c
index 9642dcad133..cd50ed04055 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -98,7 +98,7 @@ struct backtrace
 KBOARD *initial_kboard;
 KBOARD *current_kboard;
 KBOARD *all_kboards;
-int kboard_locked;
+int single_kboard;
 #else
 KBOARD the_only_kboard;
 #endif
@@ -397,7 +397,7 @@ static Lisp_Object do_mouse_tracking;
    call mouse_position_hook to get the promised position, so don't set
    it unless you're prepared to substantiate the claim!  */
 int mouse_moved;
-#endif /* HAVE_MOUSE.  */
+#endif /* HAVE_MOUSE */
 
 /* Symbols to head events.  */
 Lisp_Object Qmouse_movement;
@@ -753,10 +753,14 @@ recursive_edit_unwind (buffer)
   return Qnil;
 }
 
-#ifdef MULTI_KBOARD
 static void
-unlock_kboard ()
+any_kboard_state ()
 {
+#ifdef MULTI_KBOARD
+#if 0 /* Theory: if there's anything in Vunread_command_events,
+         it will right away be read by read_key_sequence,
+         and then if we do switch KBOARDS, it will go into the side
+         queue then.  So we don't need to do anything special here -- rms.  */
   if (CONSP (Vunread_command_events))
     {
       current_kboard->kbd_queue
@@ -764,9 +768,59 @@ unlock_kboard ()
       current_kboard->kbd_queue_has_data = 1;
     }
   Vunread_command_events = Qnil;
-  kboard_locked = 0;
+#endif
+  single_kboard = 0;
+#endif
 }
+
+/* Switch to the single-kboard state, making current_kboard
+   the only KBOARD from which further input is accepted.  */
+
+void
+single_kboard_state ()
+{
+#ifdef MULTI_KBOARD
+  single_kboard = 1;
 #endif
+}
+
+/* Maintain a stack of kboards, so other parts of Emacs
+   can switch temporarily to the kboard of a given frame
+   and then revert to the previous status.  */
+
+struct kboard_stack
+{
+  KBOARD *kboard;
+  struct kboard_stack *next;
+};
+
+static struct kboard_stack *kboard_stack;
+
+void
+push_frame_kboard (f)
+     FRAME_PTR f;
+{
+  struct kboard_stack *p
+    = (struct kboard_stack *) xmalloc (sizeof (struct kboard_stack));
+
+  p->next = kboard_stack;
+  p->kboard = current_kboard;
+  kboard_stack = p;
+
+  current_kboard = FRAME_KBOARD (f);
+}
+
+void
+pop_frame_kboard ()
+{
+  struct kboard_stack *p = kboard_stack;
+  current_kboard = p->kboard;
+  kboard_stack = p->next;
+  xfree (p);
+}
+
+/* Handle errors that are not handled at inner levels
+   by printing an error message and returning to the editor command loop.  */
 
 Lisp_Object
 cmd_error (data)
@@ -793,7 +847,7 @@ cmd_error (data)
 
   Vinhibit_quit = Qnil;
 #ifdef MULTI_KBOARD
-  unlock_kboard ();
+  any_kboard_state ();
 #endif
 
   return make_number (0);
@@ -993,7 +1047,7 @@ command_loop_1 ()
   int prev_modiff;
   struct buffer *prev_buffer;
 #ifdef MULTI_KBOARD
-  int was_locked = kboard_locked;
+  int was_locked = single_kboard;
 #endif
 
   Vdeactivate_mark = Qnil;
@@ -1338,7 +1392,7 @@ command_loop_1 ()
 
 #ifdef MULTI_KBOARD
       if (!was_locked)
-        unlock_kboard ();
+        any_kboard_state ();
 #endif
     }
 }
@@ -1661,8 +1715,8 @@ read_char (commandflag, nmaps, maps, prev_event, used_mouse_menu)
         if (kb != current_kboard)
           {
             Lisp_Object *tailp = &kb->kbd_queue;
-            /* We shouldn't get here if we were locked onto one kboard!  */
-            if (kboard_locked)
+            /* We shouldn't get here if we were in single-kboard mode!  */
+            if (single_kboard)
               abort ();
             while (CONSP (*tailp))
               tailp = &XCONS (*tailp)->cdr;
@@ -1803,11 +1857,8 @@ read_char (commandflag, nmaps, maps, prev_event, used_mouse_menu)
 
   if (NILP (c))
     {
-      /* Primary consideration goes to current_kboard's side queue.
-         If that's empty, then we check the other side queues and throw
-         if we find something there.  Finally, we read from the main queue,
-         and if that gives us something we can't use yet, we put it on the
-         appropriate side queue and try again.  */
+      /* Primary consideration goes to current_kboard's side queue.  */
+
       if (current_kboard->kbd_queue_has_data)
         {
           if (!CONSP (current_kboard->kbd_queue))
@@ -1825,50 +1876,66 @@ read_char (commandflag, nmaps, maps, prev_event, used_mouse_menu)
           Vlast_event_frame = internal_last_event_frame;
 #endif
         }
-      else
-        {
-          KBOARD *kb;
+    }
+
 #ifdef MULTI_KBOARD
-          if (!kboard_locked)
-            {
-              for (kb = all_kboards; kb; kb = kb->next_kboard)
-                if (kb->kbd_queue_has_data)
-                  {
-                    current_kboard = kb;
-                    longjmp (wrong_kboard_jmpbuf, 1);
-                  }
-            }
+  /* If current_kboard's side queue is empty check the other kboards.
+     If one of them has data that we have not yet seen here,
+     switch to it and process the data waiting for it.
+
+     Note: if the events queued up for another kboard
+     have already been seen here, and therefore are not a complete command,
+     the kbd_queue_has_data field is 0, so we skip that kboard here.
+     That's to avoid an infinite loop switching between kboards here.  */
+  if (NILP (c) && !single_kboard)
+    {
+      KBOARD *kb;
+      for (kb = all_kboards; kb; kb = kb->next_kboard)
+        if (kb->kbd_queue_has_data)
+          {
+            current_kboard = kb;
+            longjmp (wrong_kboard_jmpbuf, 1);
+          }
+    }
 #endif
 
-        wrong_kboard:
-          /* Actually read a character, waiting if necessary.  */
-          while (c = kbd_buffer_get_event (&kb), NILP (c))
+  /* Finally, we read from the main queue,
+     and if that gives us something we can't use yet, we put it on the
+     appropriate side queue and try again.  */
+  if (NILP (c))
+    {
+      KBOARD *kb;
+
+    wrong_kboard:
+
+      /* Actually read a character, waiting if necessary.  */
+      while (c = kbd_buffer_get_event (&kb), NILP (c))
+        {
+          if (commandflag >= 0
+              && !input_pending && !detect_input_pending ())
             {
-              if (commandflag >= 0
-                  && !input_pending && !detect_input_pending ())
-                {
-                  prepare_menu_bars ();
-                  redisplay ();
-                }
+              prepare_menu_bars ();
+              redisplay ();
             }
+        }
 #ifdef MULTI_KBOARD
-          if (kb != current_kboard)
-            {
-              Lisp_Object *tailp = &kb->kbd_queue;
-              while (CONSP (*tailp))
-                tailp = &XCONS (*tailp)->cdr;
-              if (!NILP (*tailp))
-                abort ();
-              *tailp = Fcons (c, Qnil);
-              kb->kbd_queue_has_data = 1;
-              if (kboard_locked)
-                goto wrong_kboard;
-              current_kboard = kb;
-              longjmp (wrong_kboard_jmpbuf, 1);
-            }
-#endif
+      if (kb != current_kboard)
+        {
+          Lisp_Object *tailp = &kb->kbd_queue;
+          while (CONSP (*tailp))
+            tailp = &XCONS (*tailp)->cdr;
+          if (!NILP (*tailp))
+            abort ();
+          *tailp = Fcons (c, Qnil);
+          kb->kbd_queue_has_data = 1;
+          if (single_kboard)
+            goto wrong_kboard;
+          current_kboard = kb;
+          longjmp (wrong_kboard_jmpbuf, 1);
         }
+#endif
     }
+
   /* Terminate Emacs in batch mode if at eof.  */
   if (noninteractive && INTEGERP (c) && XINT (c) < 0)
     Fkill_emacs (make_number (1));
@@ -2145,7 +2212,7 @@ readable_events ()
   if (FRAMEP (do_mouse_tracking) && mouse_moved)
     return 1;
 #endif
-  if (kboard_locked)
+  if (single_kboard)
     {
       if (current_kboard->kbd_queue_has_data)
         return 1;
@@ -2212,7 +2279,7 @@ kbd_buffer_store_event (event)
           KBOARD *kb;
           struct input_event *sp;
 
-          if (kboard_locked
+          if (single_kboard
               && (kb = FRAME_KBOARD (XFRAME (event->frame_or_window)),
                   kb != current_kboard))
             {
@@ -2392,10 +2459,12 @@ kbd_buffer_get_event (KBOARD **kbp)
       if (event->kind == selection_request_event)
         {
 #ifdef HAVE_X11
-          struct input_event copy = *event;
+          struct input_event copy;
+
           /* Remove it from the buffer before processing it,
              since otherwise swallow_events will see it
              and process it again.  */
+          copy = *event;
           kbd_fetch_ptr = event + 1;
           x_handle_selection_request (&copy);
 #else