Question

I came across this question:
https://softwareengineering.stackexchange.com/questions/87077/how-can-a-code-editor-effectively-hint-at-code-nesting-level-without-using-inde
and thought that Vim might be able to do something similar as well with a plugin.

I believe the indentation level could be indicated with the a sign (icon in GUI, text with highlighting in term). The piece I’m not sure about is displaying the lines without indentation. Does anyone know, is it possible and/or how you would do it?

This question is not whether or not displaying indentation levels in this manner is desirable; but how to accomplish it in Vim.

Answer 1

You could use the conceal feature that is new in 7.3.

Here is a function that does roughly what the article is describing (for spaces; accounting for tabs instead would be a fairly trivial addition):

function! IndentationHeatMap()
    set conceallevel=1
    for i in range(1,9)
        let indentation = repeat(" ", &sts * i)
        exe 'syntax match NonText "^' . indentation . '" conceal cchar=' . i
    endfor
endfunction

A solution closer to what you are requesting might use conceal to hide all leading whitespace with


syntax match NonText "^\s\+" conceal


and then use signs to provide the indicators based on custom calculations.

Note: NonText in these syntax commands is an arbitrary highlight group.