if exists("b:did_indent")
    finish
endif


function! s:CountMatches(line, pats)
    let matches = 0
    for p in a:pats
        let idx = 0
        while idx >= 0
            let idx = match(a:line, p, idx)
            if idx > 0
                let matches = matches + 1
                let idx = idx + strlen(p)
            endif
        endwhile
    endfor
    return matches
endfunction

function! GetMyrIndent(ln)
    let ln = a:ln

    if ln == 1
        let ind = 0
    else
        let prevln = getline(ln - 1)
        let curln = getline(ln)

        let inpat = ['if','while','for',
                \    'pkg','trait',
                \    'struct', 'union',
                \    '{', ':\s*$']
        let outpat = ['}',';;']
        let outalone = '^\(\s*}\s*\|\s*;;\s*\)$'
        let ind = indent(ln - 1)
        let width = &tabstop

        let n_in = s:CountMatches(prevln, inpat)
        let n_out = s:CountMatches(prevln, outpat)
        if curln =~ outalone
            let ind = ind - &tabstop
        elseif  prevln !~ outalone
            let ind = ind + (n_in - n_out) * &tabstop
        endif
    endif
    return ind
endfunction

set indentkeys+=0},;
set indentexpr=GetMyrIndent(v:lnum)

let b:did_indent = 1