Experiment and Routine

Musings of a part-time hacker

Lazy Vim Completion

Vim has a great completion system, capable of intelligently supporting a whole range of filetypes, and overall is a great piece of the vim picture. The key feature that I was hoping to find was the ability to trigger completion and move through the list of completion options using a single key combo, preferably on the home row. What follows is my current method for doing this.

What You Get

  • Ctrl-j triggers C-x C-i keyword completion, great for long variables & method names
  • Ctrl-k triggers C-x C-o omni completion, mostly used in css files
  • After triggering completion, subsequent Ctrl-j/k will cycle up and down the menu of potential completions

Note, these will override the default insert mode Ctrl-j/k key mappings, but these provide “Begin a new line” and “Enter a digraph” respectively, so I don’t mind losing them.

How to Get It

The code for each of the keymaps is a single ternary expression that checks to see if the completion menu is visible, then either opens it or cycles within it.

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" Use j/k to start, then scroll through autocomplete options
inoremap <expr> <C-j> ((pumvisible())?("\<C-n>"):("\<C-x><c-i>"))
inoremap <expr> <C-k> ((pumvisible())?("\<C-p>"):("\<C-x><c-o>"))

Room for Improvement

My main gripe with how I currently have this working is that the completion menu often presents completion options in the reverse order to what I would want. It looks as though vim searches down through the current file to provide the list of potential completions, but most often I am looking for a variable from a few lines above. I am guessing I can get vim to search upward but have yet to feel a strong need to do this.

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