\n\e"

exe "normal \p"

" Some 'constants' for ease of addressing with []
let uline="U"
let bld="B"
let itl="I"

" Loop over all lines in the original text
let end = line("$")
let lnum = 1
while lnum <= end

  " Get the current line, with tabs expanded to spaces when needed
  let line = getline(lnum)
  if match(line, "\t") >= 0
    exe lnum . "retab!"
    let did_retab = 1
    let line = getline(lnum)
  else
    let did_retab = 0
  endif
  let len = strlen(line)
  let new = ""

  " Loop over each character in the line
  let col = 1
  while col <= len
    let startcol = col " The start column for processing text
    let id = synID(lnum, col, 1)
    let col = col + 1
    " Speed loop (it's small - that's the trick)
    " Go along till we find a change in synID
    while col <= len && id == synID(lnum, col, 1) | let col = col + 1 | endwhile

    " output the text with the same synID, with all its attributes
    " The first part turns attributes into  [U][I][B]
    let id = synIDtrans(id)
    let new = new . HTMLPutText(uline[synIDattr(id, "underline", "gui") - 1] . itl[synIDattr(id, "italic", "gui") - 1] . bld[synIDattr(id, "bold", "gui") - 1], synIDattr(id, "bg#", "gui"), synIDattr(id, "fg#", "gui"), strpart(line, startcol - 1, col - startcol))
    if col > len
      break
    endif
  endwhile
  if did_retab
    undo
  endif

  exe "normal \pa" . strtrans(new) . "\n\e\p"
  let lnum = lnum + 1
  +
endwhile
" Finish with the last line
exe "normal \pa