implemented the ^W command for refreshing the screen in loops, for sleeping and also the CTRL+L immediate editing command

* ^W can be added to loops in order to view progress in interactive mode.
  It also sleeps for a given number of milliseconds (10ms by default).
* In batch mode it is therefore the sleep command.
* Since CTRL+W is an immediate editing command, you will usually type it Caret+W.
  ASCII 23 however will also be accepted.
* While ^W only updates the screen, you can force a complete redraw by pressing CTRL+L.
  This is what most terminal applications use for redrawing.
  It will make it harder to insert ASCII 12, but this is seldom necessary since it
  is a form feed.
  ^L (ASCII 12 and the upcaret variant ) is still a whitespace character and therefore treated as a NOP.
* DEC TECO had CTRL+W as the refresh immediate editing command.
  Video TECO uses <ET> as a regular command for refreshign in loops.
  I'd rather keep ET reserved as a potential terminal configuration command
  as in DEC TECO, though.

1 files changed, 42 insertions, 1 deletions

diff --git a/src/core-commands.c b/src/core-commands.c
index a2d3c92..c71ee95 100644
--- a/src/core-commands.c
+++ b/src/core-commands.c
@@ -1605,6 +1605,46 @@ teco_state_control_time(teco_machine_main_t *ctx, GError **error)
 	}
 }
 
+/*$ ^W refresh sleep delay wait
+ * [n]^W -- Wait and refresh screen
+ *
+ * First sleep <n> milliseconds before refreshing the view,
+ * i.e. drawing it.
+ * By default it sleeps for 10ms.
+ * This can be added to loops to make progress visible
+ * in interactive mode.
+ * In batch mode this command is useful as a sleep command.
+ * Sleeps can of course be interrupted with CTRL+C.
+ *
+ * Since CTRL+W is an immediate editing command, you may
+ * have to type this command in upcaret mode.
+ * To enforce a complete screen redraw you can also
+ * press CTRL+L.
+ */
+static void
+teco_state_control_refresh(teco_machine_main_t *ctx, GError **error)
+{
+	teco_int_t ms;
+
+	if (!teco_expressions_pop_num_calc(&ms, 10, error))
+		return;
+
+	while (ms > 0 && !teco_interface_is_interrupted()) {
+		/*
+		 * UNIX' usleep() would also be interrupted by
+		 * SIGINT, but polling for interruptions is
+		 * probably precise enough.
+		 * We need this as a fallback anyway.
+		 */
+		g_usleep(MIN(ms*1000, TECO_POLL_INTERVAL));
+		ms -= TECO_POLL_INTERVAL/1000;
+	}
+
+	teco_interface_unfold();
+	teco_interface_ssm(SCI_SCROLLCARET, 0, 0);
+	teco_interface_refresh(FALSE);
+}
+
 static teco_state_t *
 teco_state_control_input(teco_machine_main_t *ctx, gunichar chr, GError **error)
 {
@@ -1647,7 +1687,8 @@ teco_state_control_input(teco_machine_main_t *ctx, gunichar chr, GError **error)
 		['Y']  = {&teco_state_start, teco_state_control_last_range},
 		['S']  = {&teco_state_start, teco_state_control_last_length},
 		['T']  = {&teco_state_start, teco_state_control_typeout,
-		          .modifier_colon = 1}
+		          .modifier_colon = 1},
+		['W']  = {&teco_state_start, teco_state_control_refresh}
 	};
 
 	/*