xC/fancy-prompt.lua: remove old Readline hacks

plugins/xC/fancy-prompt.lua

@@ -14,19 +14,7 @@
 -- OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 -- CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 --
--- Beware that it is a hack and only goes about 90% of the way, which is why
--- this functionality is only available as a plugin in the first place
--- (well, and also for customizability).
---
--- The biggest problem is that the way we work with Readline is incompatible
--- with multiline prompts, and normal newlines just don't work.  This is being
--- circumvented by using an overflowing single-line prompt with a specially
--- crafted character in the rightmost column that prevents the bar's background
--- from spilling all over the last line.
---
--- There is also a problem with C-r search rendering not clearing out the
--- background but to really fix that mode, we'd have to fully reimplement it
--- since its alternative prompt very often gets overriden by accident anyway.
+-- This might go directly to xC, though it's more customizable as a plugin.
 
 xC.hook_prompt (function (hook)
 	local current = xC.current_buffer
@@ -67,11 +55,7 @@ xC.hook_prompt (function (hook)
 		x = x .. " (" .. active:sub (2) .. ")"
 	end
 
-	-- Readline 7.0.003 seems to be broken and completely corrupts the prompt.
-	-- However 8.0.004 seems to be fine with these, as is libedit 20191231-3.1.
-	--x = x:gsub("[\128-\255]", "?")
-
-	-- Align to the terminal's width and apply formatting, including the hack.
+	-- Align to the terminal's width and apply formatting.
 	local lines, cols = xC.get_screen_size ()
 	local trailing, width = " ", xC.measure (x)
 	while cols > 0 and width >= cols do
@@ -79,10 +63,10 @@ xC.hook_prompt (function (hook)
 		trailing, width = ">", xC.measure (x)
 	end
 
+	-- xC automatically smartly wraps the line.
 	x = "\x01\x1b[0;4;1;38;5;16m\x1b[48;5;" .. bg_color .. "m\x02" ..
-		x .. string.rep (" ", cols - width - 1) ..
-		"\x01\x1b[0;4;1;7;38;5;" .. bg_color .. "m\x02" ..
-		trailing .. "\x01\x1b[0;1m\x02"
+		x .. string.rep (" ", cols - width - 1) .. trailing ..
+		"\x01\x1b[0;1m\x02"
 
 	local user_prefix = function (chan, user)
 		for i, chan_user in ipairs (chan.users) do
@@ -104,10 +88,6 @@ xC.hook_prompt (function (hook)
 			if modes ~= "" then x = x .. "(" .. modes .. ")" end
 		end
 		x = x .. "] "
-	else
-		-- There needs to be at least one character so that the cursor
-		-- doesn't get damaged by our hack in that last column
-		x = x .. "> "
 	end
 	return x
 end)

xC.c

@@ -314,7 +314,7 @@ input__redisplay (struct input *self)
 	//   Also preferrably avoid using input__str_tputs(),
 	//   though this requires continuous transcoding to the locale encoding.
 	struct str prompt = str_make ();
-	bool passthrough = false;
+	bool passthrough = false, clear_line = false;
 	struct input_pos pos = { .y = 0, .x = 0 };
 
 	const char *p = self->prompt;
@@ -327,11 +327,17 @@ input__redisplay (struct input *self)
 			passthrough = true;
 		else if (ch == INPUT_END_IGNORE)
 			passthrough = false;
+		else if (passthrough)
+			str_append_data (&prompt, p, ch_len);
 		else
 		{
-			if (passthrough)
-				;
-			else if (ch == '\n')
+			// Let any passthrough sequences reset formatting first,
+			// so that this newline doesn't cause an unnecessary BCE on scroll.
+			if (clear_line)
+				str_append_c (&prompt, '\n');
+
+			clear_line = false;
+			if (ch == '\n')
 			{
 				pos.y++;
 				pos.x = 0;
@@ -340,11 +346,13 @@ input__redisplay (struct input *self)
 			else
 				// FIXME: Either convert from Unicode to wchar_t here,
 				//   or implement the algorithm ourselves.
-				input__adjust (&pos, wcwidth (ch));
+				clear_line = input__adjust (&pos, wcwidth (ch));
 			str_append_data (&prompt, p, ch_len);
 		}
 		p += ch_len;
 	}
+	if (clear_line)
+		str_append_c (&prompt, '\n');
 
 	if (self->y)
 		putp (tparm (parm_up_cursor, self->y, 0, 0, 0, 0, 0, 0, 0, 0));