perf: perform syntax highlighting async

README.md

@@ -205,10 +205,9 @@ require("quicker").setup({
   -- Keep the cursor to the right of the filename and lnum columns
   constrain_cursor = true,
   highlight = {
-    -- Use treesitter highlights. Can be true, false, or "fast"
-    -- "fast" - only use highlights from buffers that are already parsed
+    -- Use treesitter highlighting
     treesitter = true,
-    -- Use LSP semantic token highlights
+    -- Use LSP semantic token highlighting
     lsp = true,
   },
   -- Options for customizing the display of the quickfix list

doc/quicker.txt

@@ -38,10 +38,9 @@ OPTIONS                                                          *quicker-option
       -- Keep the cursor to the right of the filename and lnum columns
       constrain_cursor = true,
       highlight = {
-        -- Use treesitter highlights. Can be true, false, or "fast"
-        -- "fast" - only use highlights from buffers that are already parsed
+        -- Use treesitter highlighting
         treesitter = true,
-        -- Use LSP semantic token highlights
+        -- Use LSP semantic token highlighting
         lsp = true,
       },
       -- Options for customizing the display of the quickfix list
@@ -99,10 +98,8 @@ setup({opts})                                                      *quicker.setu
                              options in `opts`
           {highlight}        `nil|quicker.SetupHighlightConfig` Configure syntax
                              highlighting
-              {treesitter} `nil|boolean|"fast"` Enable treesitter syntax
-                           highlighting. "fast" will only use highlights from
-                           buffers that are already parsed
-              {lsp}        `nil|boolean` Use LSP semantic token highlights
+              {treesitter} `nil|boolean` Enable treesitter syntax highlighting
+              {lsp}        `nil|boolean` Use LSP semantic token highlighting
           {edit}             `nil|quicker.SetupEditConfig`
               {enabled}  `nil|boolean`
               {autosave} `nil|boolean|"unmodified"`

lua/quicker/config.lua

@@ -26,10 +26,9 @@ local default_config = {
   -- Keep the cursor to the right of the filename and lnum columns
   constrain_cursor = true,
   highlight = {
-    -- Use treesitter highlights. Can be true, false, or "fast"
-    -- "fast" - only use highlights from buffers that are already parsed
+    -- Use treesitter highlighting
     treesitter = true,
-    -- Use LSP semantic token highlights
+    -- Use LSP semantic token highlighting
     lsp = true,
   },
   -- Options for customizing the display of the quickfix list
@@ -157,12 +156,12 @@ end
 ---@field soft_end? string
 
 ---@class (exact) quicker.HighlightConfig
----@field treesitter boolean|"fast"
+---@field treesitter boolean
 ---@field lsp boolean
 
 ---@class (exact) quicker.SetupHighlightConfig
----@field treesitter? boolean|"fast" Enable treesitter syntax highlighting. "fast" will only use highlights from buffers that are already parsed
----@field lsp? boolean Use LSP semantic token highlights
+---@field treesitter? boolean Enable treesitter syntax highlighting
+---@field lsp? boolean Use LSP semantic token highlighting
 
 ---@class (exact) quicker.EditConfig
 ---@field enabled boolean

lua/quicker/display.lua

@@ -105,8 +105,48 @@ local function calc_whitespace_prefix(items)
   return prefixes
 end
 
+-- Highlighting can be slow because it requires loading buffers and parsing them with treesitter, so
+-- we pipeline it and break it up with defers to keep the editor responsive.
+local add_qf_highlights
+local _pending_highlights = {}
+local _running = false
+local function do_next_highlight()
+  if _running then
+    return
+  end
+  _running = true
+  local next_info = table.remove(_pending_highlights, 1)
+  if next_info then
+    local ok, err = xpcall(add_qf_highlights, debug.traceback, next_info)
+    if not ok then
+      error(err)
+    end
+  end
+  if #_pending_highlights > 0 then
+    vim.defer_fn(function()
+      _running = false
+      do_next_highlight()
+    end, 20)
+  else
+    _running = false
+  end
+end
 ---@param info QuickFixTextFuncInfo
-local function add_qf_highlights(info)
+local function schedule_highlights(info)
+  for _, i in ipairs(_pending_highlights) do
+    -- If we're already processing a highlight for this quickfix, just expand the range
+    if i.id == info.id and i.winid == info.winid and i.quickfix == info.quickfix then
+      i.start_idx = math.min(i.start_idx, info.start_idx)
+      i.end_idx = math.max(i.end_idx, info.end_idx)
+      return
+    end
+  end
+  table.insert(_pending_highlights, info)
+  vim.schedule(do_next_highlight)
+end
+
+---@param info QuickFixTextFuncInfo
+add_qf_highlights = function(info)
   local b = config.display.borders
   local qf_list
   if info.quickfix == 1 then
@@ -131,14 +171,15 @@ local function add_qf_highlights(info)
   vim.api.nvim_buf_clear_namespace(qf_list.qfbufnr, err_ns, 0, -1)
   local prefixes = vim.b[qf_list.qfbufnr].qf_prefixes or {}
 
+  local start = vim.uv.hrtime() / 1e6
   for i = info.start_idx, info.end_idx do
     ---@type QuickFixItem
     local item = qf_list.items[i]
-    if item.bufnr ~= 0 then
+    local line = lines[i]
+    if item.bufnr ~= 0 and line then
       if not vim.api.nvim_buf_is_loaded(item.bufnr) then
         vim.fn.bufload(item.bufnr)
       end
-      local line = lines[i]
       local src_line = vim.api.nvim_buf_get_lines(item.bufnr, item.lnum - 1, item.lnum, false)[1]
 
       -- If the lines differ only in leading whitespace, we should add highlights anyway and adjust
@@ -196,6 +237,14 @@ local function add_qf_highlights(info)
     elseif user_data.header == "soft" then
       vim.api.nvim_buf_add_highlight(qf_list.qfbufnr, ns, "QuickFixHeaderSoft", i - 1, 0, -1)
     end
+
+    -- If we've been processing for too long, defer to preserve editor responsiveness
+    local delta = vim.uv.hrtime() / 1e6 - start
+    if delta > 50 then
+      info.start_idx = i + 1
+      schedule_highlights(info)
+      return
+    end
   end
 end
 
@@ -313,7 +362,7 @@ function M.quickfixtextfunc(info)
 
   -- If we just rendered the last item, add highlights
   if info.end_idx == #items then
-    vim.schedule_wrap(add_qf_highlights)(info)
+    schedule_highlights(info)
 
     -- If we have appended some items to the quickfix, we need to update qf_items (just the appended ones)
     if qf_list.qfbufnr > 0 then

lua/quicker/highlight.lua

@@ -1,4 +1,3 @@
-local config = require("quicker.config")
 local M = {}
 
 ---@class quicker.TSHighlight
@@ -38,7 +37,7 @@ function M.buf_get_ts_highlights(bufnr, lnum)
   end
 
   local row = lnum - 1
-  if config.highlight.treesitter ~= "fast" and not parser:is_valid() then
+  if not parser:is_valid() then
     parser:parse(true)
   end