------------------------------------------------------------------------
-- main lexer function
------------------------------------------------------------------------
function luaX:llex(ls, Token)
  ls.buff = ""
  while true do
    local c = ls.current
    ----------------------------------------------------------------
    if self:currIsNewline(ls) then
      self:inclinenumber(ls)
    ----------------------------------------------------------------
    elseif c == "-" then
      c = self:nextc(ls)
      if c ~= "-" then return "-" end
      -- else is a comment
      local sep = -1
      if self:nextc(ls) == '[' then
        sep = self:skip_sep(ls)
        ls.buff = ""  -- 'skip_sep' may dirty the buffer
      end
      if sep >= 0 then
        self:read_long_string(ls, nil, sep)  -- long comment
        ls.buff = ""
      else  -- else short comment
        while not self:currIsNewline(ls) and ls.current ~= "EOZ" do
          self:nextc(ls)
        end
      end
    ----------------------------------------------------------------
    elseif c == "[" then
      local sep = self:skip_sep(ls)
      if sep >= 0 then
        self:read_long_string(ls, Token, sep)
        return "TK_STRING"
      elseif sep == -1 then
        return "["
      else
        self:lexerror(ls, "invalid long string delimiter", "TK_STRING")
      end
    ----------------------------------------------------------------
    elseif c == "=" then
      c = self:nextc(ls)
      if c ~= "=" then return "="
      else self:nextc(ls); return "TK_EQ" end
    ----------------------------------------------------------------
    elseif c == "<" then
      c = self:nextc(ls)
      if c ~= "=" then return "<"
      else self:nextc(ls); return "TK_LE" end
    ----------------------------------------------------------------
    elseif c == ">" then
      c = self:nextc(ls)
      if c ~= "=" then return ">"
      else self:nextc(ls); return "TK_GE" end
    ----------------------------------------------------------------
    elseif c == "~" then
      c = self:nextc(ls)
      if c ~= "=" then return "~"
      else self:nextc(ls); return "TK_NE" end
    ----------------------------------------------------------------
    elseif c == "\"" or c == "'" then
      self:read_string(ls, c, Token)
      return "TK_STRING"
    ----------------------------------------------------------------
    elseif c == "." then
      c = self:save_and_next(ls)
      if self:check_next(ls, ".") then
        if self:check_next(ls, ".") then
          return "TK_DOTS"   -- ...
        else return "TK_CONCAT"   -- ..
        end
      elseif not string.find(c, "%d") then
        return "."
      else
        self:read_numeral(ls, Token)
        return "TK_NUMBER"
      end
    ----------------------------------------------------------------
    elseif c == "EOZ" then
      return "TK_EOS"
    ----------------------------------------------------------------
    else  -- default
      if string.find(c, "%s") then
        -- lua_assert(self:currIsNewline(ls))
        self:nextc(ls)
      elseif string.find(c, "%d") then
        self:read_numeral(ls, Token)
        return "TK_NUMBER"
      elseif string.find(c, "[_%a]") then
        -- identifier or reserved word
        repeat
          c = self:save_and_next(ls)
        until c == "EOZ" or not string.find(c, "[_%w]")
        local ts = ls.buff
        local tok = self.enums[ts]
        if tok then return tok end  -- reserved word?
        Token.seminfo = ts
        return "TK_NAME"
      else
        self:nextc(ls)
        return c  -- single-char tokens (+ - / ...)
      end
    ----------------------------------------------------------------
    end--if c
  end--while
end

return luaX