List @ tag auto completes in vim

I'd like to plant a number of @tags (e.g. @sea_ice, @models) in my markdown files when editing in vim. Currently I'm using SuperTab to tab-complete ordinary words. However if I hit <tab> after the @ symbol, it won't give me a list of all @tags, but rather a long list of all words found in the current context.

I noticed that SuperTab allows custom context definitions, however, as I know nothing about vim scripting and the documentation contains only 2 examples, I'm unable to script it myself.

After bit searching around I think I probably need to define a new custom omni complete function, specifically the 2nd half of the function:

function! TagComplete(findstart, base) if a:findstart " locate the start of the word let line = getline('.') let start = col('.') - 1 while start > 0 && line[start - 1] != '@' let start -= 1 endwhile return start else " find @tag let res = [] ???? ???? endif return res endif endfun

This is the code I'm working on. But I don't know how to test it or where is the right place to put it. Please help

Thanks

After quite a bit of struggling and searching for help, I figured out one solution.

Firstly create a completefunc that searches for @tags in the current file (Credits to cherryberryterry: https://www.reddit.com/r/vim/comments/4dg1rx/how_to_define_custom_omnifunc_in_vim_seeking/):

function! CompleteTags(findstart, base)
    if a:findstart
        return match(matchstr(getline('.'), '.*\%' . col('.') . 'c'), '.*\(^\|\s\)\zs@')
    else
        let matches = []

        " position the cursor on the last column of the last line
        call cursor(line('$'), col([line('$'), '$']))

        " search backwards through the buffer for all matches
        while searchpos('\%(^\|\s\)\zs' . (empty(a:base) ? '@' : a:base) . '[[:alnum:]_]*', 'bW') != [0, 0]
            let matches += [matchstr(getline('.'), '\%' . col('.') . 'c@[[:alnum:]_]*')]
        endwhile

        return filter(matches, "v:val != '@'")
    endif
endfunction
set completefunc=CompleteTags

The put the following in .vimrc to setup tab-completion using SuperTab:

function! TagCompleteContext()
    let line = getline('.')
    if line[col('.') - 2] == '@'
        return "\<c-x>\<c-u>"
    endif
endfunction


let g:SuperTabDefaultCompletionType = "context"
let g:SuperTabCompletionContexts = ['TagCompleteContext', 's:ContextText']
let g:SuperTabContextDefaultCompletionType = "<c-p>"