Re: How a load reader can pre-parse chunks?

[Varanda <m@...>]

Thanks V.

As incomplete is checking for LUA_ERRSYNTAX I guess in Lua I can do similar thing by checking “near <eof>” error.

So my shell looks like:

LUA_PROMPT = "Lua> "

LUA_PROMPT_MULTI = "Lua>> "

function luashell( ctx )

  print_sl ("Lua EOS Shell version 0.01\nCopyrights 2021 Varanda Labs\n\n" .. LUA_PROMPT)

  

  -- subscribe for events

  res,msg = eos.subscribe_event_by_name(ctx, "EV_SYS_TEXT_FROM_CONSOLE")

  if res == false then

    print(msg)

  end

  local f,msg, ok

  local err

  local chunk = ""

  local more = false

  while(1) do

    local ev, arg = eos.wait_event(ctx)

    if more == true then

      chunk = chunk .. arg

      f, msg = load(chunk)

    else

      f, msg = load(arg)

    end

    if f == nil then

      if string.find(msg, "<eof>") ~= nil then

        if more == false then -- if first time:

          chunk = chunk .. arg

          more = true

        end

        print_sl(LUA_PROMPT_MULTI)

      else

        print(“load error: " .. msg)

        chunk = ""

        more = false

      end

    else

      --local ok, e = xpcall( f, lua_error_handler )

      local ok, msg = pcall(f)

      if ok == false then

        print(msg)

      end

      chunk = ""

      more = false

      print_sl(LUA_PROMPT)

    end

  end

end

On Mar 12, 2021, at 8:18 AM, v <v19930312@gmail.com> wrote:

On Fri, 2021-03-12 at 07:59 -0500, Varanda wrote:

Hello All,

I am implementing a Lua shell using load function.
It is working fine for single line entries. I would like to add
multiline support WITHOUT adding a explicit multi-line line
terminator (like ‘\’ in C and makefiles)

Question: Is there a parser that the reader can use to figure out
when the chunk is completed?

For example, what could be done inside the following “chunk_reader”
for detecting it?
Or should the load caller keep calling it based on “<eof>” presence
in the error message?
Thanks in advance,
Varanda

Vanilla Lua REPL checks if it can compile chunk as entered and expects
continuation if it can't. If such continuation is an empty string,
input buffer gets reset and error is printed.
--
v <v19930312@gmail.com>