" https://github.com/mbbill/undotree/blob/master/plugin/undotree.vim
"=================================================
"Options:

" Window layout
" style 1
" +----------+------------------------+
" |          |                        |
" |          |                        |
" | undotree |                        |
" |          |                        |
" |          |                        |
" +----------+                        |
" |          |                        |
" |   diff   |                        |
" |          |                        |
" +----------+------------------------+
" Style 2
" +----------+------------------------+
" |          |                        |
" |          |                        |
" | undotree |                        |
" |          |                        |
" |          |                        |
" +----------+------------------------+
" |                                   |
" |   diff                            |
" |                                   |
" +-----------------------------------+
" Style 3
" +------------------------+----------+
" |                        |          |
" |                        |          |
" |                        | undotree |
" |                        |          |
" |                        |          |
" |                        +----------+
" |                        |          |
" |                        |   diff   |
" |                        |          |
" +------------------------+----------+
" Style 4
" +-----------------------++----------+
" |                        |          |
" |                        |          |
" |                        | undotree |
" |                        |          |
" |                        |          |
" +------------------------+----------+
" |                                   |
" |                            diff   |
" |                                   |
" +-----------------------------------+
if !exists('g:undotree_WindowLayout')
    let g:undotree_WindowLayout = 2
endif

if has("persistent_undo")
   let target_path = expand('~/.vim/undodir')

    " create the directory and any parent directories
    " if the location does not exist.
    if !isdirectory(target_path)
        call mkdir(target_path, "p", 0700)
    endif

    let &undodir=target_path
    set undofile
endif

nnoremap <Leader>u :UndotreeToggle<CR>