Add 'buffer-delete' plugin

I was having trouble with slow `<C-p>` completion, and figured out it
was due to the fact that I had about 300 buffers open.

Many of these buffers weren't being actively used, and were just loaded
in from Vim sessions past. When I removed the unloaded buffers,
completion sped up like a whistle.

Thanks to 'sidyll' (https://stackoverflow.com/users/557306/sidyll) on
Stack Overflow for explaining how to get "all" buffer numbers (or at
least all possible buffer numbers up to the highest one open), as well
as the filtering logic:
https://stackoverflow.com/questions/17931507/vimscript-number-of-listed-buffers/17933352#17933352

I leveraged the above to get the buffer numbers of all unloaded buffers,
then delete the buffers by number.

It was originally a temporary command-mode line, but I decided it could
be beneficial to save the code just in case I need it again.

1 files changed, 11 insertions, 0 deletions

diff --git a/bundle/buffer-delete/autoload/buffer_delete.vim b/bundle/buffer-delete/autoload/buffer_delete.vim
new file mode 100644
index 0000000..316cfe8
--- /dev/null
+++ b/bundle/buffer-delete/autoload/buffer_delete.vim
@@ -0,0 +1,11 @@
+" Delete all unloaded buffers. These are buffers that aren't active or hidden.
+" Usually they come from a reinitialised session.
+function! buffer_delete#Unloaded()
+	let all = range(1, bufnr('$'))
+	let unloaded = filter(all, {_i, v -> !bufloaded(v)})
+
+	for i in unloaded
+		" Use silent because some buffer numbers may not exist.
+		silent! execute 'bdelete ' . i
+	endfor
+endfunction