Prevent nerdtree from rebinding <cr>

Question

I use <bs> for scrolling up half a page and <cr> for scrolling down:

I'd like the same keybindings to be available in NerdTree. It seems that o and <cr> are equivalent in file-mode in NerdTree (just based on the help text) and that <cr> doesn't seems to play much of a role in the other modes:

Is there a way to prevent NerdTree from binding <cr> at all?

More generally, what is a good general strategy (if one exists) for "reclaiming" a keybinding from an overzealous plugin without too many side effects?

Answer 1

I don't know much about NerdTree, but according to :h NERDTreeKeymapAPI, you can use a function provided by the plugin, NERDTreeAddKeyMap(), to override default mappings:

4.1. Key map API                                           *NERDTreeKeymapAPI*

NERDTreeAddKeyMap({options})                             *NERDTreeAddKeyMap()*
    Adds a new keymapping for all NERD tree buffers.
    {options} must be a dictionary, and must contain the following keys:
    "key" - the trigger key for the new mapping
    "callback" - the function the new mapping will be bound to
    "quickhelpText" - the text that will appear in the quickhelp (see
    |NERDTree-?|)
    "override" - if 1 then this new mapping will override whatever previous
    mapping was defined for the key/scope combo. Useful for overriding the
    default mappings.

    Additionally, a "scope" argument may be supplied. This constrains the
    mapping so that it is only activated if the cursor is on a certain object.
    That object is then passed into the handling method. Possible values are:
        "FileNode" - a file node
        "DirNode" - a directory node
        "Node" - a file or directory node
        "Bookmark" - A bookmark
        "all" - the keymap is not constrained to any scope (default). When
        thei is used, the handling function is not passed any arguments.


    Example: >
        call NERDTreeAddKeyMap({
            \ 'key': 'foo',
            \ 'callback': 'NERDTreeCDHandler',
            \ 'quickhelpText': 'echo full path of current node',
            \ 'scope': 'DirNode' })

        function! NERDTreeCDHandler(dirnode)
            call a:dirnode.changeToDir()
        endfunction
<
    This code should sit in a file like ~/.vim/nerdtree_plugin/mymapping.vim.
    It adds a (redundant) mapping on 'foo' which changes vim's CWD to that of
    the current dir node. Note this mapping will only fire when the cursor is
    on a directory node.

In your case, if you want CR to act as C-d, to scroll down half a page, you could write in ~/.vim/after/plugin/my_nerdtree.vim (you can create the missing directories if ~/.vim/after/plugin/ doesn't exist on your system):

call NERDTreeAddKeyMap({
\                       'key': '<cr>',
\                       'callback': {-> feedkeys("\<c-d>", 'int')},
\                      })

More generally, you can use ~/.vim/after/plugin/my_plugin.vim to override whatever customization was done by a third-party plugin.

So, if NerdTree didn't provide this public function, in the same file as before, you could install an autocmd listening to FileType, which would remap CR to C-d, but only in a NerdTree buffer:

augroup my_nerdtree
    au!
    au FileType nerdtree nnoremap <buffer> <cr> <c-d>
augroup END

Although, both methods are not exactly equivalent here. The public function seems to provide more control over the mapping, and it could even be more reliable, I don't know.