perf(cmdline): prevent unneeded redraws during cmdline preview (subst…

…itute). Fixes #803

lua/noice/ui/cmdline.lua

@@ -156,6 +156,7 @@ end
 
 ---@type NoiceCmdline[]
 M.cmdlines = {}
+M.skipped = false
 
 function M.on_show(event, content, pos, firstc, prompt, indent, level)
   local c = Cmdline({
@@ -167,6 +168,14 @@ function M.on_show(event, content, pos, firstc, prompt, indent, level)
     indent = indent,
     level = level,
   })
+
+  -- This was triggered by a force redraw, so skip it
+  if c:get():find(Hacks.SPECIAL, 1, true) then
+    M.skipped = true
+    return
+  end
+  M.skipped = false
+
   local last = M.cmdlines[level] and M.cmdlines[level].state
   if not vim.deep_equal(c.state, last) then
     M.active = c
@@ -189,7 +198,11 @@ function M.on_hide(_, level)
 end
 
 function M.on_pos(_, pos, level)
-  if M.cmdlines[level] and M.cmdlines[level].state.pos ~= pos then
+  if M.skipped then
+    return
+  end
+  local c = M.cmdlines[level]
+  if c and c.state.pos ~= pos then
     M.cmdlines[level].state.pos = pos
     M.update()
   end

lua/noice/util/hacks.lua

@@ -241,15 +241,14 @@ function M.fix_cmp()
   end)
 end
 
+M.SPECIAL = "Þ"
 function M.cmdline_force_redraw()
   if not require("noice.util.ffi").cmdpreview then
     return
   end
 
-  -- HACK: this will trigger redraw during substitute and cmdpreview,
-  -- but when moving the cursor, the screen will be cleared until
-  -- a new character is entered
-  vim.api.nvim_feedkeys(" " .. Util.BS, "n", true)
+  -- HACK: this will trigger redraw during substitute and cmdpreview
+  vim.api.nvim_feedkeys(M.SPECIAL .. Util.BS, "n", true)
 end
 
 ---@type string?

lua/noice/util/init.lua

@@ -18,6 +18,8 @@ M.ESC = M.t("<esc>")
 M.BS = M.t("<bs>")
 M.EXIT = M.t("<C-\\><C-n>")
 M.LUA_CALLBACK = "\x80\253g"
+M.RIGHT = M.t("<right>")
+M.LEFT = M.t("<left>")
 M.CMD = "\x80\253h"
 
 ---@generic F: fun()
@@ -325,6 +327,9 @@ function M.debug(data)
   if not fd then
     error(("Could not open file %s for writing"):format(file))
   end
+  if type(data) ~= "string" then
+    data = vim.inspect(data)
+  end
   fd:write(data .. "\n")
   fd:close()
 end