Mapping <esc> in vimrc causes bizarre arrow behaviour - vim

I am a happy VIM user, although I admit I'm quite far from being fluent. I found this nice post:
Vim clear last search highlighting and I thought I'd become a better person if I didn't have to hammer away a random character sequence every time I did a search. Now, I'm also using the vimrc config from here:
http://amix.dk/vim/vimrc.html
and the problem I have is that when I add the line nnoremap <esc> :noh<return><esc> to it (it doesn't seem to make a difference where I put it) I get awkward behaviour when I use arrows in command mode, namely letters from A to D appear in a newline and I get switched to insert mode.
There has to be some mapping conflict but for the life of me I can't figure out where it is.
EDIT: As it follows from the answers it turns out the Ultimate vimrc part is not relevant, the mentioned nnoremap command will cause altered arrow behaviour even if it's the only vimrc entry. Changing title to a more informative one.
PS. I know I shouldn't use arrows, hopefully I'll get there one day.

The mapping
nnoremap <esc> :noh<return><esc>
will conflict with so called "grey keys" and I believe that it should be used either in GVim only or in terminal Vim by someone who does not use special keys like arrows.
From what I know (and guess) how Vim processes keys, I would say that it's impossible to do anything with this. For Vim to recognize special key all its components should go in a row, so when you press Arrow Left Vim gets the following sequence of codes:
<esc> [ D
But after your mapping Arrow Left becomes:
: n o h l <cr> <esc>
[ D
Vim sees two separate sequences and treats <esc> as a single press of Escape key, thus next two codes of Left Arrow key lose their special meaning.
So I suggest you to map :noh to some other key sequence (e.g. to one starting with <leader>, see :help mapleader; I don't recommend you to use F-keys, using them is as bad as using of arrow keys).

The cause had been explained well, but solution was not mentioned. However there is a straight one.
If you’ll tell to Vim explicitly that there are key sequences starting from <esc>[
:nnoremap <silent><esc> :noh<CR>
:nnoremap <esc>[ <esc>[
than when single <esc> will be pressed Vim will wait for a second (or different time, see :h 'timeoutlen') or for a next key (second <esc> for example) and only then replace it with :noh<CR>.

This solution preserves the ESC mapping to :nohlsearch.
The comment on this answer explaining why this is happening tells us that the root cause is the TermResponse behavior of vim. This can be compensated for by wrapping the mapping in an autocommand for the TermResponse event.
This ensures that the binding doesn't happen until after the term response is set, which prevents Esc from also sending a string like ]>1;3201;0c to vim.
Change your line in vimrc to this:
augroup no_highlight
autocmd TermResponse * nnoremap <esc> :noh<return><esc>
augroup END
The augroup commands are not strictly necessary, but they prevent multiple mappings when you reload your vimrc without quitting vim.
EDIT: If you also use a graphical vim like Gvim or Macvim, the TermResponse event will not fire. Assuming you use a single vimrc, you'll need some additional code like
if has('gui_running')
nnoremap <silent> <esc> :nohlsearch<return><esc>
else
" code from above
augroup no_highlight
autocmd TermResponse * nnoremap <esc> :noh<return><esc>
augroup END
end

Problem is that when you press an arrow terminal emits something like <Esc>OA. Vim part that supports terminal seems to use the same mapping mechanism to do the job as you are using: while nmap <Esc>OA will tell you nothing, call feedkeys("\eOA") will move one line up and call feedkeys("\eOA", 'n') will add letter A beyond current line. With your mapping being noremappable you forbid vim to use <Esc> as a part of the key. The problem is that you need remappable mapping here, but can have remappable mapping without it being recursive as well only if it starts with {lhs}, but <Esc>:noh<CR>OA is not going to work. I thought the following code will (it uses <expr> and function with side effect to make <Esc> be the first character of the actual {rhs} and still launch :noh), but in fact it does not:
function s:NoHlSearch()
nohlsearch
return "\e"
endfunction
nmap <expr> <Esc> <SID>NoHlSearch()
. I have no other idea how to solve the problem of having non-recursive remappable mapping which includes {lhs} but not at the start.

I have had good luck with this
if $TERM =~ 'xterm'
set noek
endif
nnoremap <silent> <esc> <esc>:noh<cr>
The disadvantage is that function keys can not be used in insert mode.
:h ek

Related

Dont creep backwards on vim escape, without using <esc> mapping

I have previously used the following vim mapping so that when I press esc, vim does not 'creep backwards':
:inoremap <silent> <Esc> <Esc>`^
However, this has quite unexpected side-effects (to me, at least), for example, now that I have an <Esc> on the lhs, the arrow keys won't work anymore in insert mode (and a few other items that send escape sequences to vim.
Is there a better way to do this, or perhaps a settings within vim that alters this behavior? Ultimately, I want the behavior or <Esc>`^, I just don't want to have an <esc> that is mapped on the lhs for other reasons. What would be the best approach here?
No need to remap <ESC>. You could try using this autocmd in your .vimrc:
au InsertLeave * call cursor(getcurpos()[1], getcurpos()[2]+1)
This code is a reimplementation of the approach described in the Vim wiki, which is more verbose (and possibly outdated). The command has a small latency though.

VIM: set term=xterm changes <BS> to <Del>, is it reversible?

I have added set term=xterm to my vimrc to be able to use 256-color vim schemes in terminal, but it comes at a price (at least for me). It also replaces (sort of) the BackSpace with Delete (i.e. BackSpace starts to delete forward just like Delete does) in insert mode and makes it "BackSpace" instead of moving left (or h) in normal mode. I have nothing against Ctrl-H as a way "to Backspace", but I simply don't want to have two delete buttons and ability "to BackSpace" (delete backward) in normal mode.
How can I reverse that change while retaining the setting I need?
PS I've read :h CTRL-h and a bit of :h xterm, but I couldn't find the solution.
Vim's inoremap and nnoremap commands can be used to adjust how keys are interpreted in Vim.
A solution is documented here for your specific context: https://conemu.github.io/en/VimXterm.html
The relevant quote:
"If you have problems with BS in Vim (BS acts like Delete key) under ConEmu when term=xterm, you may try to remap BS key:
inoremap <Char-0x07F> <BS>
nnoremap <Char-0x07F> <BS>
"
In general, when a key does not do what you want, the trick is to find out what it actually sends to Vim. Sometimes hitting Ctrl-V followed by that key in insert mode might help figure it out. Then inoremap and nnoremap as shown above can be used to reassign it to the behaviour you want in insert and normal modes, respectively.

Adding to mapping rather than completely remapping

I'm working on a plugin to allow bracket completion (I know it's available, it's more of a learning exercise). To properly implement it, I need to add to the backspace mapping. However, as it's an important key, I'd rather keep the existing functionality and just add to it rather than reimplementing the functionality. The steps would basically be when in insert mode and press backspace, execute the original backspace key, then check for some conditions and maybe remove more characters.
I've tried something like imap <backspace> <backspace><call_func_here>, but that doesn't seem to work. Again, I know I could remap backspace to just the function and try to recreate the backspace functionality, but I'd prefer to not do that.
Is this possible in vim?
I think what you are trying to do is the following:
inoremap <silent> <BS> <BS><C-o>:call MyFunction()<CR>
inoremap allows to create a non recurrent mapping in insert mode (it is often a good idea to use nore in your mappings). :h :inoremap
<silent> precise that the mapping will not be echoed on the command line (You will not see :call MyFunction() in the command line) :h :map-silent
<BS> is the reference to the backspace key that you want to remap.
The second <BS> is here to issue a backspace in insert mode
<C-o> switches to normal mode for only a command. :h i_CTRL-O
:call MyFunction() is the call to your function the way you would do it in normal mode.
<CR> correspond to the Enter key which validate the call to your function.

Setting mouse=a and mapping <esc> to :noh breaks mouse working on vim? [duplicate]

I am a happy VIM user, although I admit I'm quite far from being fluent. I found this nice post:
Vim clear last search highlighting and I thought I'd become a better person if I didn't have to hammer away a random character sequence every time I did a search. Now, I'm also using the vimrc config from here:
http://amix.dk/vim/vimrc.html
and the problem I have is that when I add the line nnoremap <esc> :noh<return><esc> to it (it doesn't seem to make a difference where I put it) I get awkward behaviour when I use arrows in command mode, namely letters from A to D appear in a newline and I get switched to insert mode.
There has to be some mapping conflict but for the life of me I can't figure out where it is.
EDIT: As it follows from the answers it turns out the Ultimate vimrc part is not relevant, the mentioned nnoremap command will cause altered arrow behaviour even if it's the only vimrc entry. Changing title to a more informative one.
PS. I know I shouldn't use arrows, hopefully I'll get there one day.
The mapping
nnoremap <esc> :noh<return><esc>
will conflict with so called "grey keys" and I believe that it should be used either in GVim only or in terminal Vim by someone who does not use special keys like arrows.
From what I know (and guess) how Vim processes keys, I would say that it's impossible to do anything with this. For Vim to recognize special key all its components should go in a row, so when you press Arrow Left Vim gets the following sequence of codes:
<esc> [ D
But after your mapping Arrow Left becomes:
: n o h l <cr> <esc>
[ D
Vim sees two separate sequences and treats <esc> as a single press of Escape key, thus next two codes of Left Arrow key lose their special meaning.
So I suggest you to map :noh to some other key sequence (e.g. to one starting with <leader>, see :help mapleader; I don't recommend you to use F-keys, using them is as bad as using of arrow keys).
The cause had been explained well, but solution was not mentioned. However there is a straight one.
If you’ll tell to Vim explicitly that there are key sequences starting from <esc>[
:nnoremap <silent><esc> :noh<CR>
:nnoremap <esc>[ <esc>[
than when single <esc> will be pressed Vim will wait for a second (or different time, see :h 'timeoutlen') or for a next key (second <esc> for example) and only then replace it with :noh<CR>.
This solution preserves the ESC mapping to :nohlsearch.
The comment on this answer explaining why this is happening tells us that the root cause is the TermResponse behavior of vim. This can be compensated for by wrapping the mapping in an autocommand for the TermResponse event.
This ensures that the binding doesn't happen until after the term response is set, which prevents Esc from also sending a string like ]>1;3201;0c to vim.
Change your line in vimrc to this:
augroup no_highlight
autocmd TermResponse * nnoremap <esc> :noh<return><esc>
augroup END
The augroup commands are not strictly necessary, but they prevent multiple mappings when you reload your vimrc without quitting vim.
EDIT: If you also use a graphical vim like Gvim or Macvim, the TermResponse event will not fire. Assuming you use a single vimrc, you'll need some additional code like
if has('gui_running')
nnoremap <silent> <esc> :nohlsearch<return><esc>
else
" code from above
augroup no_highlight
autocmd TermResponse * nnoremap <esc> :noh<return><esc>
augroup END
end
Problem is that when you press an arrow terminal emits something like <Esc>OA. Vim part that supports terminal seems to use the same mapping mechanism to do the job as you are using: while nmap <Esc>OA will tell you nothing, call feedkeys("\eOA") will move one line up and call feedkeys("\eOA", 'n') will add letter A beyond current line. With your mapping being noremappable you forbid vim to use <Esc> as a part of the key. The problem is that you need remappable mapping here, but can have remappable mapping without it being recursive as well only if it starts with {lhs}, but <Esc>:noh<CR>OA is not going to work. I thought the following code will (it uses <expr> and function with side effect to make <Esc> be the first character of the actual {rhs} and still launch :noh), but in fact it does not:
function s:NoHlSearch()
nohlsearch
return "\e"
endfunction
nmap <expr> <Esc> <SID>NoHlSearch()
. I have no other idea how to solve the problem of having non-recursive remappable mapping which includes {lhs} but not at the start.
I have had good luck with this
if $TERM =~ 'xterm'
set noek
endif
nnoremap <silent> <esc> <esc>:noh<cr>
The disadvantage is that function keys can not be used in insert mode.
:h ek

Any potential problems with these remaps?

I wanted to add a way to run :noh that made the most sense to me, so I added the following
nnoremap / :noh<CR>/
nnoremap ? :noh<CR>?
So far it's working exactly how I expected (and want): hilights are cleared as another search is started and typing /<backspace> makes more sense for me than <leader><space> or similar.
My concern is that this will somehow break other useful commands or a plugin.
Anyone know if I'm safe doing this? Thanks.
What you can break in third party plugins
Every mapping that you define can break plugins, if they are badly written, or if they rely on mappings that you have redefined.
Consider a plugin that uses map instead of noremap or normal instead of normal!: if the right-hand side of that mapping or the normal mode commands include /, then your mapping will be triggered.
Still, it wo'nt break much, it's just a matter of display.
What you can break in a normal use of vim
But there is still a case where you break something: Try this
iI am typing in insert modeCTRL-O/helloEnter
Normally, CTRL-O in insert mode temporarily switches to normal mode for one command. You've just broken that, because the call to  :noh consumes that command.
You still can do it this way:
function ResetPattern(forward)
noh
redraw
return a:forward ? '/' : '?'
endfunction
nnoremap <expr> / ResetPattern(1)
nnoremap <expr> ? ResetPattern(0)
I think it's safe. But, it will lose some functionality.
For example:
Type /helloEnter will highlight all hello
Type /world to inc-search, then type ESC to return where you are. But the original highlight is lost.
I just have this mapping in my .vimrc:
nmap <BS> :noh<CR>
Normal mode mapping <C-l> usually refreshes the screen. I have modified it to clear highlightings. Easily available and comes from a reflex nowadays. Doesn't destroy any functionality and clearing the highlights can be thought as a part of the screen refreshing.
nnoremap <C-l> :nohl<CR><C-l>

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