Date completion

[redstreet]

With vim-ledger, if I press Tab on the first column on an empty row, autocompletion enters the current date. I miss this feature, and this would be a great addition to vim-beancount if it's easy to add in.
https://github.com/ledger/vim-ledger

(Please feel free to delete this issue if this is not of interest).
Thanks!

[yegle]

Even better, I've come up with a smart solution.

The idea is: assume your transactions are ordered in chronicle order and you want to keep in that way, using the following vim function will find the right place (the last transaction whose date is <= today), place the cursor there, enter current date and leave vim in insert mode.

If you don't have transactions in a future date then it can be simplified a lot.

@nathangrigg let me know if you want to include this, I can send a PR.

function GotoInsertPosition()
    let today=strftime("%Y-%m-%d")
    let f=bufname("%")
    let cmd="grep ^20 ".f."|sort|awk '{ if($1 > \"".today."\") { printf \"%s\",lastday; found=1; exit; } lastday=$1 } END {if(!found) printf \"%s\",lastday}'"
    let lastday=system(cmd)
    let cmd="awk '/^".lastday."/,/^$/{lineno=NR} END {printf \"%d\",lineno}' ".f
    let lineno=system(cmd)
    execute ":".lineno
    execute "normal! yyppk"
    execute "normal! i".today." *"
    execute ":startinsert!"
endfunction
nnoremap <C-x> :call GotoInsertPosition()<CR>