Turn off all auto-insertion/leaving when not perfectly balanced. about vim-smartinput HOT 1 OPEN

let g:skip_sc = 'synIDattr(synID(line("."), col("."), 0), "name") =~ "[Ss]tring\\|[Cc]omment\\|[Ss]pecial"'
function! InsideString( ... )
    let l = a:0 ? a:1 : line('.')
    let c = a:0 ? a:2 : col('.')
    if &syntax == ''
        " No help from syntax engine,
        " count quote characters up to the cursor position
        let line = strpart( getline(l), 0, c - 1 )
        let line = substitute( line, '\\"', '', 'g' )
        let quotes = substitute( line, '[^"]', '', 'g' )
        return len(quotes) % 2
    endif
    return SynIDMatch( '[Ss]tring', l, c, 0 )
endfunction

function! IsBalanced()
    let l = line( '.' )
    let c =  col( '.' )
    let line = getline( '.' )
    let matchb = max( [l-1000, 1] )   " 1000 is max lookahead
    let matchf = min( [l+1000, line('$')] )
    let p1 = searchpair( '(', '', ')', 'brnmW', g:skip_sc, matchb )
    let p2 = searchpair( '(', '', ')',  'rnmW', g:skip_sc, matchf )
    if !(p1 == p2) && !(p1 == p2 - 1 && line[c-1] == '(') && !(p1 == p2 + 1 && line[c-1] == ')')
        " Number of opening and closing parens differ
        return 0
    endif

    let b1 = searchpair( '\[', '', '\]', 'brnmW', g:skip_sc, matchb )
    let b2 = searchpair( '\[', '', '\]',  'rnmW', g:skip_sc, matchf )
    if !(b1 == b2) && !(b1 == b2 - 1 && line[c-1] == '[') && !(b1 == b2 + 1 && line[c-1] == ']')
        " Number of opening and closing brackets differ
        return 0
    endif
    let b1 = searchpair( '{', '', '}', 'brnmW', g:skip_sc, matchb )
    let b2 = searchpair( '{', '', '}',  'rnmW', g:skip_sc, matchf )
    if !(b1 == b2) && !(b1 == b2 - 1 && line[c-1] == '{') && !(b1 == b2 + 1 && line[c-1] == '}')
        " Number of opening and closing curly braces differ
        return 0
    endif
    return 1
endfunction

" Is the current cursor position inside a comment?
function! InsideComment( ... )
    let l = a:0 ? a:1 : line('.')
    let c = a:0 ? a:2 : col('.')
    if &syntax == ''
        " No help from syntax engine,
        " remove strings and search for ';' up to the cursor position
        let line = strpart( getline(l), 0, c - 1 )
        let line = substitute( line, '\\"', '', 'g' )
        let line = substitute( line, '"[^"]*"', '', 'g' )
        return match( line, ';' ) >= 0
    endif
    return SynIDMatch( '[Cc]omment', l, c, 1 )
endfunction