[erlang-patches] Scan "=<<" as something useful

Robert Virding <>
Thu May 9 22:23:51 CEST 2013


Sorry Raimo,

But I have been travelling and not really following erlang-patches. I still hold the same opinion. Consider yourself lectured. :-)

Robert

----- Original Message -----
> From: "Raimo Niskanen" <>
> 
> On Sun, Apr 21, 2013 at 10:15:28PM +0200, Anthony Ramine wrote:
> > Hello,
> > 
> > I've noticed that Erlang/OTP own code tend to be space-free, e.g.
> > {a,
> > b} is rather written as {a,b}. Then there is the occasional Bin=
> > <<42>> with a space because erl_scan will scans "=<<" as '=<','<'
> > instead of '=','<<'. This patch teaches erl_scan how to not do
> > that.
> > 
> > There is no backwards compatibility problem as '=<','<' can't
> > appear
> > in valid code.
> 
> When I tried to fix this years ago while rewriting the scanner just
> after
> the binary syntax was introduced I got lecutured (I think by Robert)
> that it was a bad change because it introduces syntax knowledge
> into the scanner.
> 
> The scanner is today greedy so it collects as many characters as it
> can into a valid token, and "=<" is a valid token.  When it is
> followed by "<" that becomes a syntax error in the parser.
> 
> I kind of miss this argument this time around...
> 
> > 
> >         git fetch https://github.com/nox/otp.git
> >         disambiguate-equal-binary
> > 
> >         https://github.com/nox/otp/compare/disambiguate-equal-binary
> >         https://github.com/nox/otp/compare/disambiguate-equal-binary.patch
> > 
> > Regards,
> > 
> > --
> > Anthony Ramine
> > _______________________________________________
> > erlang-patches mailing list
> > 
> > http://erlang.org/mailman/listinfo/erlang-patches
> 
> --
> 
> / Raimo Niskanen, Erlang/OTP, Ericsson AB
> _______________________________________________
> erlang-patches mailing list
> 
> http://erlang.org/mailman/listinfo/erlang-patches
> 


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