perf(preview): re-use existing preview when preview is for the same file

lua/trouble/view/preview.lua

@@ -71,52 +71,56 @@ function M.create(item, opts)
     end
   end
 
+  return buf
+end
+
+---@param view trouble.View
+---@param item trouble.Item
+---@param opts? {scratch?:boolean}
+function M.open(view, item, opts)
+  if M.item() == item then
+    return
+  end
+  if M.preview and M.preview.item.filename ~= item.filename then
+    M.close()
+  end
+
+  if not M.preview then
+    local buf = M.create(item, opts)
+    if not buf then
+      return
+    end
+
+    M.preview = M.preview_win(buf, view)
+
+    M.preview.buf = buf
+    M.preview.item = item
+  end
+
+  Render.reset(M.preview.buf)
+
   -- make sure we highlight at least one character
   local end_pos = { item.end_pos[1], item.end_pos[2] }
   if end_pos[1] == item.pos[1] and end_pos[2] == item.pos[2] then
     end_pos[2] = end_pos[2] + 1
   end
 
   -- highlight the line
-  Util.set_extmark(buf, Render.ns, item.pos[1] - 1, 0, {
+  Util.set_extmark(M.preview.buf, Render.ns, item.pos[1] - 1, 0, {
     end_row = end_pos[1],
     hl_group = "CursorLine",
     hl_eol = true,
     strict = false,
   })
 
   -- highlight the range
-  Util.set_extmark(buf, Render.ns, item.pos[1] - 1, item.pos[2], {
+  Util.set_extmark(M.preview.buf, Render.ns, item.pos[1] - 1, item.pos[2], {
     end_row = end_pos[1] - 1,
     end_col = end_pos[2],
     hl_group = "TroublePreview",
     strict = false,
   })
 
-  return buf
-end
-
----@param view trouble.View
----@param item trouble.Item
----@param opts? {scratch?:boolean}
-function M.open(view, item, opts)
-  if M.item() == item then
-    return
-  end
-  if M.preview then
-    M.close()
-  end
-
-  local buf = M.create(item, opts)
-  if not buf then
-    return
-  end
-
-  M.preview = M.preview_win(buf, view)
-
-  M.preview.buf = buf
-  M.preview.item = item
-
   -- no autocmds should be triggered. So LSP's etc won't try to attach in the preview
   Util.noautocmd(function()
     if pcall(vim.api.nvim_win_set_cursor, M.preview.win, item.pos) then