-- luatbl2xml
-- A very simple converter from lua tables to xml

function luatbl2xml (tbl, tb)
  local tab = tb or 0;
  local eltname = '';
  local attrs = ''

  -- Get the tagname and attributes
  for k, v in pairs (tbl) do
    if type (k) == "number" then
      if k == 1 then
        eltname = v;
      end
    elseif type (k) == "string" then
      attrs = attrs .. ' ' .. k .. '="' .. v .. '"'
    end
  end

  -- Go recursively into children
  local children = ''
  for k, v in pairs (tbl) do
    if k ~= 1 and type(v) == 'table' then
      children = children .. luatbl2xml (v, tab+2) .. '\n';
    end
  end

  if children ~= '' then
    local begin_elt = "<" .. eltname .. attrs .. ">\n";
    for i=1, tab do
      begin_elt = ' ' .. begin_elt
    end

    local end_elt = "</" .. eltname .. ">"
    for i=1, tab do
      end_elt = ' ' .. end_elt
    end

    return begin_elt .. children .. end_elt

  else
    local begin_end_elt = "<" .. eltname .. attrs .. "/>";

    for i=1, tab do
      begin_end_elt = ' ' .. begin_end_elt
    end

    return begin_end_elt
  end
end

doc =
{"ncl", id="myid",
  {"body", id="body",
    {"port", component="m1"},
    {"media", id="m1", src="video.mp4"},
    {"link", id="l1",
      {"bind", role="onEnd", component="m1"},
      {"bind", role="start", component="m1"}
    }
  }
}

print (luatbl2xml (doc))