on-demand calculation and update of option info

Using metatables to calculate info strings on render, we can avoid
precomputing it for all options when generating the menu, making certain
menus open much faster. This also allows us to update dynamic info, e.g.
the currently programme, while the menu is open.

1 files changed, 9 insertions, 5 deletions

diff --git a/state.lua b/state.lua
index da26a9a..a88fe41 100644
--- a/state.lua
+++ b/state.lua
@@ -167,7 +167,7 @@ function menu_mt:update_search_matches()
 
 	local options = {}
 	for _, v in ipairs(self.search_options) do
-		local matches = {}
+		local matches
 
 		local name = v.name
 		if not case_sensitive then
@@ -180,13 +180,17 @@ function menu_mt:update_search_matches()
 			if not i then
 				break
 			end
+			matches = matches or {}
 			matches[#matches+1] = {start = i, stop = j}
 		end
 
-		if #matches > 0 then
-			local t = util.copy_table(v)
-			t.matches = matches
-			options[#options+1] = t
+		if matches then
+			-- search options may contain dynamic data that is
+			-- updated on redraw. using a proxy table instead of
+			-- copying prevents potential updates on every change
+			-- of search text.
+			options[#options+1] = setmetatable(
+				{matches = matches}, {__index = v})
 		end
 	end