Simplify TUI C-x 2 binding

The TUI "C-x 2" binding tries to switch to a different layout based on
the current layout.  Once user-defined layouts are available, this
won't really make sense.  I wasn't entirely sure how to handle this.

This patch changes the binding to simply cycle through the existing
layouts.  I considered this a reasonable, though not ideal,
compromise.

gdb/ChangeLog
2020-02-22  Tom Tromey  <tom@tromey.com>

	* tui/tui.c (tui_rl_change_windows): Call tui_next_layout.
	* tui/tui-layout.h (tui_next_layout): Declare.
	* tui/tui-layout.c (tui_next_layout): New function.

Change-Id: Ic101f0e3831a4235a048b3090ef60f025f7449bb

4 files changed, 18 insertions, 36 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e35d5c5..4ab0309 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2020-02-22  Tom Tromey  <tom@tromey.com>
 
+	* tui/tui.c (tui_rl_change_windows): Call tui_next_layout.
+	* tui/tui-layout.h (tui_next_layout): Declare.
+	* tui/tui-layout.c (tui_next_layout): New function.
+
+2020-02-22  Tom Tromey  <tom@tromey.com>
+
 	* tui/tui-regs.c (tui_data_window::display_registers_from): Use
 	correct coordinates.
 
diff --git a/gdb/tui/tui-layout.c b/gdb/tui/tui-layout.c
index ce1f6a7..6a998e8 100644
--- a/gdb/tui/tui-layout.c
+++ b/gdb/tui/tui-layout.c
@@ -278,6 +278,13 @@ tui_layout_command (const char *layout_name, int from_tty)
   tui_set_layout (new_layout);
 }
 
+/* See tui-layout.h.  */
+
+void
+tui_next_layout ()
+{
+  tui_layout_command ("next", 0);
+}
 
 static void
 extract_display_start_addr (struct gdbarch **gdbarch_p, CORE_ADDR *addr_p)
diff --git a/gdb/tui/tui-layout.h b/gdb/tui/tui-layout.h
index 37f07c2..7e4b7b7 100644
--- a/gdb/tui/tui-layout.h
+++ b/gdb/tui/tui-layout.h
@@ -181,6 +181,9 @@ extern void tui_add_win_to_layout (enum tui_win_type);
 
 extern void tui_set_layout (enum tui_layout_type);
 
+/* Switch to the next layout.  */
+extern void tui_next_layout ();
+
 /* Apply the current layout.  */
 extern void tui_apply_current_layout ();
 
diff --git a/gdb/tui/tui.c b/gdb/tui/tui.c
index 0a59837..74bf32d 100644
--- a/gdb/tui/tui.c
+++ b/gdb/tui/tui.c
@@ -140,8 +140,7 @@ tui_rl_switch_mode (int notused1, int notused2)
 /* TUI readline command.
    Change the TUI layout to show a next layout.
    This function is bound to CTRL-X 2.  It is intended to provide
-   a functionality close to the Emacs split-window command.  We
-   always show two windows (src+asm), (src+regs) or (asm+regs).  */
+   a functionality close to the Emacs split-window command.  */
 static int
 tui_rl_change_windows (int notused1, int notused2)
 {
@@ -149,41 +148,8 @@ tui_rl_change_windows (int notused1, int notused2)
     tui_rl_switch_mode (0 /* notused */, 0 /* notused */);
 
   if (tui_active)
-    {
-      enum tui_layout_type new_layout;
-
-      new_layout = tui_current_layout ();
-
-      /* Select a new layout to have a rolling layout behavior with
-	 always two windows (except when undefined).  */
-      switch (new_layout)
-	{
-	case SRC_COMMAND:
-	  new_layout = SRC_DISASSEM_COMMAND;
-	  break;
-
-	case DISASSEM_COMMAND:
-	  new_layout = SRC_DISASSEM_COMMAND;
-	  break;
-
-	case SRC_DATA_COMMAND:
-	  new_layout = SRC_DISASSEM_COMMAND;
-	  break;
-
-	case SRC_DISASSEM_COMMAND:
-	  new_layout = DISASSEM_DATA_COMMAND;
-	  break;
-	  
-	case DISASSEM_DATA_COMMAND:
-	  new_layout = SRC_DATA_COMMAND;
-	  break;
+    tui_next_layout ();
 
-	default:
-	  new_layout = SRC_COMMAND;
-	  break;
-	}
-      tui_set_layout (new_layout);
-    }
   return 0;
 }