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Groups > comp.lang.c > #72674

Re: Error handling in a parser (return value or setjmp)

From Ian Collins <ian-news@hotmail.com>
Newsgroups comp.lang.c
Subject Re: Error handling in a parser (return value or setjmp)
Date 2015-10-13 15:54 +1300
Message-ID <d83a3tFlf7cU1@mid.individual.net> (permalink)
References <mvhqgq$28c$1@speranza.aioe.org>

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Morten W. Petersen wrote:
> Hoi.
>
> OK, so I'm working on my Smash XML parser, and have gotten around to
> dealing with errors and failures.
>
> The way I see it, there are two ways of dealing with errors, one is
> passing around a state variable and checking it after function calls,
> the other is setjmp/longjmp.
>
> There are two main things that can fail in the parser, one is that the
> input is invalid, the other is that it runs out of memory.
>
> If it runs out of memory, some clean-ups and reorganization can be
> attempted, and if that fails, it is a fatal error.
>
> Invalid input is another fatal error.
>
> The most cost-effective way to do this, is setting a setjmp as a
> failure simply jumps to some pre-defined place, while checking
> return values involves more work, for example on each iteration
> in the parser loop.

Using error returns makes your code easier to read and avoids 
unnecessary coupling.  I've yet to see setjmp used as an effective error 
handling strategy.  There ave been attempts at "poor man's exceptions" 
using setjmp, but none have caught on.

If you encounter invalid input, print the best diagnostic you can and 
bail.  Do the same for out of memory.  Trying to garbage collect is 
probably more trouble than t is worth, especially early on in a project. 
  Don't forget that you might not be able to recover memory if the error 
is down to fragmentation.

-- 
Ian Collins

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Thread

Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-13 04:33 +0200
  Re: Error handling in a parser (return value or setjmp) Ian Collins <ian-news@hotmail.com> - 2015-10-13 15:54 +1300
    Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-13 05:07 +0200
  Re: Error handling in a parser (return value or setjmp) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-13 14:07 +0100
    Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-13 16:17 +0200
    Re: Error handling in a parser (return value or setjmp) supercat@casperkitty.com - 2015-10-13 08:26 -0700
      Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-13 18:14 +0200
        Re: Error handling in a parser (return value or setjmp) Ian Collins <ian-news@hotmail.com> - 2015-10-14 07:46 +1300
          Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-13 22:06 +0200
            Re: Error handling in a parser (return value or setjmp) Ian Collins <ian-news@hotmail.com> - 2015-10-14 10:32 +1300
              Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-13 23:47 +0200
                Re: Error handling in a parser (return value or setjmp) Ian Collins <ian-news@hotmail.com> - 2015-10-14 11:02 +1300
                Re: Error handling in a parser (return value or setjmp) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-10-14 18:32 +0000
                Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-15 12:28 +0200
                Re: Error handling in a parser (return value or setjmp) Ian Collins <ian-news@hotmail.com> - 2015-10-16 07:47 +1300
            Re: Error handling in a parser (return value or setjmp) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-10-13 21:39 +0000
              Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-13 23:49 +0200
                Re: Error handling in a parser (return value or setjmp) supercat@casperkitty.com - 2015-10-13 15:03 -0700
                Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-14 01:16 +0200
                Re: Error handling in a parser (return value or setjmp) Geoff <geoff@invalid.invalid> - 2015-10-13 16:46 -0700
                Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-14 02:13 +0200
                Re: Error handling in a parser (return value or setjmp) Geoff <geoff@invalid.invalid> - 2015-10-13 19:10 -0700
                Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-14 04:27 +0200
                Re: Error handling in a parser (return value or setjmp) Ian Collins <ian-news@hotmail.com> - 2015-10-14 16:05 +1300
                Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-14 05:18 +0200
                Re: Error handling in a parser (return value or setjmp) Ian Collins <ian-news@hotmail.com> - 2015-10-14 16:31 +1300
                Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-14 05:44 +0200
                Re: Error handling in a parser (return value or setjmp) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-10-15 12:06 +0000
                Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-15 16:08 +0200
                Re: Error handling in a parser (return value or setjmp) supercat@casperkitty.com - 2015-10-14 00:36 -0700
                Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-15 12:32 +0200
                Re: Error handling in a parser (return value or setjmp) Ian Collins <ian-news@hotmail.com> - 2015-10-14 11:06 +1300
                Re: Error handling in a parser (return value or setjmp) David Brown <david.brown@hesbynett.no> - 2015-10-14 00:10 +0200
                Re: Error handling in a parser (return value or setjmp) James Kuyper <jameskuyper@verizon.net> - 2015-10-13 19:08 -0400
              Re: Error handling in a parser (return value or setjmp) raltbos@xs4all.nl (Richard Bos) - 2015-10-14 11:37 +0000
                Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-15 12:34 +0200
                Re: Error handling in a parser (return value or setjmp) Ian Collins <ian-news@hotmail.com> - 2015-10-16 07:56 +1300
                Re: Error handling in a parser (return value or setjmp) "Morten W. Petersen" <morphex@gmail.com> - 2015-10-16 05:45 +0200
            Re: Error handling in a parser (return value or setjmp) James Kuyper <jameskuyper@verizon.net> - 2015-10-13 18:53 -0400

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