Make TUI react to "set style enabled"

When the user toggles "set style enabled", the TUI should react by
redrawing the source window, if necessary.  This patch implements this
behavior.

No test because the TUI is generally not tested.

This version of the patch incorporates Pedro's patch to provide a
clean way to force the TUI to update the source window's contents.

gdb/ChangeLog
2019-03-14  Pedro Alves  <palves@redhat.com>
	    Tom Tromey  <tromey@adacore.com>

	* tui/tui-winsource.h (tui_refill_source_window): Declare.
	* tui/tui-winsource.c (tui_refill_source_window): New function,
	from...
	(tui_horizontal_source_scroll): ... here.  Move some logic.
	* cli/cli-style.c (set_style_enabled): Notify new observable.
	* tui/tui-hooks.c (tui_redisplay_source): New function.
	(tui_attach_detach_observers): Attach or detach
	tui_redisplay_source.
	* observable.h (source_styling_changed): New observable.
	* observable.c: Define source_styling_changed observable.

3 files changed, 40 insertions, 19 deletions

diff --git a/gdb/tui/tui-hooks.c b/gdb/tui/tui-hooks.c
index 98c6fd6..4a1d79e 100644
--- a/gdb/tui/tui-hooks.c
+++ b/gdb/tui/tui-hooks.c
@@ -204,6 +204,18 @@ tui_normal_stop (struct bpstats *bs, int print_frame)
   tui_refresh_frame_and_register_information (/*registers_too_p=*/1);
 }
 
+/* Observer for source_cache_cleared.  */
+
+static void
+tui_redisplay_source ()
+{
+  if (tui_is_window_visible (SRC_WIN))
+    {
+      /* Force redisplay.  */
+      tui_refill_source_window (tui_win_list[SRC_WIN]);
+    }
+}
+
 /* Token associated with observers registered while TUI hooks are
    installed.  */
 static const gdb::observers::token tui_observers_token {};
@@ -239,6 +251,8 @@ tui_attach_detach_observers (bool attach)
 		    tui_normal_stop, attach);
   attach_or_detach (gdb::observers::register_changed,
 		    tui_register_changed, attach);
+  attach_or_detach (gdb::observers::source_styling_changed,
+		    tui_redisplay_source, attach);
 }
 
 /* Install the TUI specific hooks.  */
diff --git a/gdb/tui/tui-winsource.c b/gdb/tui/tui-winsource.c
index 9336f7b..7fd460b 100644
--- a/gdb/tui/tui-winsource.c
+++ b/gdb/tui/tui-winsource.c
@@ -306,8 +306,32 @@ tui_show_source_content (struct tui_win_info *win_info)
   win_info->generic.content_in_use = TRUE;
 }
 
+/* Refill the source window's source cache and update it.  If WIN_INFO
+   is a disassembly window, then just update it.  */
+
+void
+tui_refill_source_window (struct tui_win_info *win_info)
+{
+  symtab *s = nullptr;
+
+  if (win_info->generic.type == SRC_WIN)
+    {
+      symtab_and_line cursal = get_current_source_symtab_and_line ();
+      s = (cursal.symtab == NULL
+	   ? find_pc_line_symtab (get_frame_pc (get_selected_frame (NULL)))
+	   : cursal.symtab);
+    }
+
+  tui_update_source_window_as_is (win_info,
+				  win_info->detail.source_info.gdbarch,
+				  s,
+				  win_info->generic.content[0]
+				    ->which_element.source.line_or_addr,
+				  FALSE);
+}
 
 /* Scroll the source forward or backward horizontally.  */
+
 void
 tui_horizontal_source_scroll (struct tui_win_info *win_info,
 			      enum tui_scroll_direction direction,
@@ -315,20 +339,7 @@ tui_horizontal_source_scroll (struct tui_win_info *win_info,
 {
   if (win_info->generic.content != NULL)
     {
-      struct gdbarch *gdbarch = win_info->detail.source_info.gdbarch;
       int offset;
-      struct symtab *s = NULL;
-
-      if (win_info->generic.type == SRC_WIN)
-	{
-	  struct symtab_and_line cursal
-	    = get_current_source_symtab_and_line ();
-
-	  if (cursal.symtab == NULL)
-	    s = find_pc_line_symtab (get_frame_pc (get_selected_frame (NULL)));
-	  else
-	    s = cursal.symtab;
-	}
 
       if (direction == LEFT_SCROLL)
 	offset = win_info->detail.source_info.horizontal_offset
@@ -341,13 +352,8 @@ tui_horizontal_source_scroll (struct tui_win_info *win_info,
 	    offset = 0;
 	}
       win_info->detail.source_info.horizontal_offset = offset;
-      tui_update_source_window_as_is (win_info, gdbarch, s,
-				      win_info->generic.content[0]
-					->which_element.source.line_or_addr,
-				      FALSE);
+      tui_refill_source_window (win_info);
     }
-
-  return;
 }
 
 
diff --git a/gdb/tui/tui-winsource.h b/gdb/tui/tui-winsource.h
index db33a4f..920032b 100644
--- a/gdb/tui/tui-winsource.h
+++ b/gdb/tui/tui-winsource.h
@@ -56,6 +56,7 @@ extern void tui_show_source_content (struct tui_win_info *);
 extern void tui_horizontal_source_scroll (struct tui_win_info *,
 					  enum tui_scroll_direction, 
 					  int);
+extern void tui_refill_source_window (struct tui_win_info *);
 extern enum tui_status tui_set_exec_info_content (struct tui_win_info *);
 extern void tui_show_exec_info_content (struct tui_win_info *);
 extern void tui_erase_exec_info_content (struct tui_win_info *);