perf(treesitter): better foldtext and foldexpr

lua/lazyvim/util/ui.lua

@@ -1,23 +1,23 @@
 ---@class lazyvim.util.ui
 local M = {}
 
+-- foldtext for Neovim < 0.10.0
 function M.foldtext()
-  local ok = pcall(vim.treesitter.get_parser, vim.api.nvim_get_current_buf())
-  local ret = ok and vim.treesitter.foldtext and vim.treesitter.foldtext()
-  if not ret or type(ret) == "string" then
-    ret = { { vim.api.nvim_buf_get_lines(0, vim.v.lnum - 1, vim.v.lnum, false)[1], {} } }
-  end
-  table.insert(ret, { " " .. LazyVim.config.icons.misc.dots })
+  return vim.api.nvim_buf_get_lines(0, vim.v.lnum - 1, vim.v.lnum, false)[1]
+end
 
-  if not vim.treesitter.foldtext then
-    return table.concat(
-      vim.tbl_map(function(line)
-        return line[1]
-      end, ret),
-      " "
-    )
+-- optimized treesitter foldexpr for Neovim >= 0.10.0
+function M.foldexpr()
+  local buf = vim.api.nvim_get_current_buf()
+  if vim.b[buf].ts_folds == nil then
+    -- as long as we don't have a filetype, don't bother
+    -- checking if treesitter is available (it won't)
+    if vim.bo[buf].filetype == "" then
+      return "0"
+    end
+    vim.b[buf].ts_folds = pcall(vim.treesitter.get_parser, buf)
   end
-  return ret
+  return vim.b[buf].ts_folds and vim.treesitter.foldexpr() or "0"
 end
 
 ---@return {fg?:string}?
@@ -47,49 +47,6 @@ function M.color(name, bg)
   return color and string.format("#%06x", color) or nil
 end
 
-M.skip_foldexpr = {} ---@type table<number,boolean>
-local skip_check = assert(vim.uv.new_check())
-
-function M.foldexpr()
-  local buf = vim.api.nvim_get_current_buf()
-
-  -- no highlight, no foldexpr
-  if not vim.b[buf].ts_highlight then
-    return "0"
-  end
-
-  -- still in the same tick and no parser
-  if M.skip_foldexpr[buf] then
-    return "0"
-  end
-
-  -- don't use treesitter folds for terminal
-  if vim.bo[buf].buftype == "terminal" then
-    return "0"
-  end
-
-  -- as long as we don't have a filetype, don't bother
-  -- checking if treesitter is available (it won't)
-  if vim.bo[buf].filetype == "" then
-    return "0"
-  end
-
-  local ok = pcall(vim.treesitter.get_parser, buf)
-
-  if ok then
-    return vim.treesitter.foldexpr()
-  end
-
-  -- no parser available, so mark it as skip
-  -- in the next tick, all skip marks will be reset
-  M.skip_foldexpr[buf] = true
-  skip_check:start(function()
-    M.skip_foldexpr = {}
-    skip_check:stop()
-  end)
-  return "0"
-end
-
 function M.maximize()
   ---@type {k:string, v:any}[]?
   local maximized = nil