Indent with conditions

I would like to indent every line with 5 spaces when all the next conditions are matched:

1) after an empty line

2) when line starts with a Uppercase letter

3) when the line has more then 80 characters when the file has开发者_JS百科 no textwidth set

4) when the line has more then (textwidth-10) characters when the file has a textwidth set

and the next line must not start with a Uppercase letter.

Can anyone help me?

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This is completely untested, and I'm sure there are more elegant methods, but this should give you a rough idea. I scan every line in the file one at a time, and indent it if one of your conditions is met.

function! Indenter()
    let winview=winsaveview()
    try
        let this_line_num=1
        let tw = &textwidth
        while this_line_num <= line("$")
            let thisline=getline(this_line_num)
            let lastline=getline(this_line_num-1)
            let firstchar=substitute(matchstr(thisline,"^ *.")," ","","g")
            if ( matchstr(lastline,"^.") == "" && this_line_num > 1 )
                        \ || firstchar =~# "[A-Z]"
                        \ || ( tw == 0 && strlen(thisline) > 80 )
                        \ || ( tw != 0 && strlen(thisline) > tw-10
                                     \ && firstchar !~# "[A-Z]" )
                sil exe this_line_num . "s#^#     #"
            endif
            let this_line_num+=1
        endwhile
    finally
        call winrestview(winview)
    endtry
endfunction

I am assuming that "empty lines" means no whitespace (hence matchstr(lastline,"^.")) and that lines containing text can have leading whitespace (hence the substitute(matchstr()) command to get the first non-whitespace character.

Hope this helps. Let me know if it falls flat on its face.