feat(buffer_previewer): pass file details in TelescopePreviewLoaded autocmd (#2429)

README.md

@@ -400,8 +400,27 @@ to configure more filetypes, take a look at
 
 If you want to configure the `vim_buffer_` previewer (e.g. you want the line to wrap), do this:
 
-```vim
-autocmd User TelescopePreviewerLoaded setlocal wrap
+```lua
+vim.api.nvim_create_autocmd("User", {
+  pattern = "TelescopePreviewerLoaded",
+  callback = function(args)
+    if args.data.filetype ~= "help" then
+      vim.bo.number = true
+    elseif args.data.bufname:match("*.csv") then
+      vim.bo.wrap = false
+    end
+  end,
+})
+```
+
+A data field is passed to the callback, which contains the filetype and the buffer name.
+
+```lua
+{
+  title: string, # preview window title
+  filetype: string,
+  bufname: string,
+}
 ```
 
 ## Sorters

lua/telescope/previewers/buffer_previewer.lua

@@ -426,7 +426,14 @@ previewers.new_buffer_previewer = function(opts)
 
       if vim.api.nvim_buf_is_valid(self.state.bufnr) then
         vim.api.nvim_buf_call(self.state.bufnr, function()
-          vim.cmd "do User TelescopePreviewerLoaded"
+          vim.api.nvim_exec_autocmds("User", {
+            pattern = "TelescopePreviewerLoaded",
+            data = {
+              title = entry.preview_title,
+              bufname = self.state.bufname,
+              filetype = pfiletype.detect(self.state.bufname),
+            },
+          })
         end)
       end
     end)