Re: LPEG error location display

[Miles Bader <miles@...>]

Florian Weimer <fw@deneb.enyo.de> writes:
> I hit the same problem when using LPeg.  Have you found a solution in
> the meantime?

I use a function matcher that records the current position, e.g.:

   local function update_err_pos (text, pos)
      parse_state.err_pos = pos
      return pos
   end

   -- This special lpeg pattern updates the current error position
   --
   ERR_POS = P(update_err_pos)

[where "parse_state" is some global; probably better ways to do that
now, e.g., the special capture you can use to access the Nth arg of the
lpeg match call]

Then I stick ERR_POS in various places, for instance, after the
end-of-line pattern... e.g.:

   -- this matches a newline, and also updates the error location
   local WS_NL_SYNC = WS_NL * lu.ERR_POS

The error reporting routines then use the error position to find the
last line that was ever matched, and include that information along with
the error message.

-Miles

-- 
Dawn, n. When men of reason go to bed.