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Re: confusion about behavior

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Kenneth Brody <kenbrody@spamcop.net> writes:
> On 8/15/2011 12:28 AM, Seebs wrote:
> [...]
>> The "maximal munch" rule.
>>
>> "++" is a larger token than "+".  Therefore, if you see two +, it *MUST*
>> be ++, and *CANNOT* be "+", even if that later results in a syntax error.
>>
>> So:
>> 	a+++b
>> a =>  start a token
>> + =>  there is no token starting "a+", so "a" was a token, and we now have "+"
>> + =>  there is a token starting "++", and that's complete
>> + =>  start a new token, consisting of "+", keep looking...
>
> Nit:
>
> The second '+' shouldn't really say "and that's complete".
>
> The third '+' should really be "there is no '+++' token, nor does any token 
> start with it, so _now_ '++' is now complete, and we start a new token, 
> consisting of '+', keep looking".

Counter-nit:

The second '+' could say "The *only* token starting with ++ is ++
itself; therefore, that's complete".

The lexical scanner could realize that "++" is the complete token either
when it sees the second '+', or when it sees the third one.  The effect
is exactly the same either way.

>> b =>  "+b" can't be a token, so the "+" becomes a token.
>>
>> (Then we hit ";" and because "b;" can't be a token, "b" is a token and ";"
>> is a token.)
>>
>> Basically, in order for it to be "+ ++b", the compiler would have to look
>> at "++" and decide to split off the first part of it, and it can't.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Nokia
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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confusion about behavior LJ <djtheshowstopper@gmail.com> - 2011-08-14 11:56 -0700
  Re: confusion about behavior China Blue Tip Wrench <chine.bleu@yahoo.com> - 2011-08-14 12:05 -0700
  Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-14 12:06 -0700
    Re: confusion about behavior Todd Carnes <toddcarnes@gmail.com> - 2011-08-15 01:57 +0000
      Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-14 19:10 -0700
        Re: confusion about behavior Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-08-15 03:44 +0100
          Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-14 20:27 -0700
      Re: confusion about behavior Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-14 22:52 -0400
      Re: confusion about behavior Seebs <usenet-nospam@seebs.net> - 2011-08-15 04:28 +0000
        Re: confusion about behavior Kenneth Brody <kenbrody@spamcop.net> - 2011-08-15 15:31 -0400
          Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-15 12:36 -0700
          Re: confusion about behavior Seebs <usenet-nospam@seebs.net> - 2011-08-15 20:33 +0000
            Re: confusion about behavior Kenneth Brody <kenbrody@spamcop.net> - 2011-08-16 14:39 -0400
              Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-16 12:27 -0700
                Re: confusion about behavior Willem <willem@toad.stack.nl> - 2011-08-16 19:47 +0000
      Re: confusion about behavior Barry Schwarz <schwarz45@yahoo.com> - 2011-09-05 04:50 -0700
        [OT] Re: confusion about behavior Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-05 09:07 -0400
        Re: confusion about behavior Kenneth Brody <kenbrody@spamcop.net> - 2011-09-06 12:42 -0400
  Re: confusion about behavior James Kuyper <jameskuyper@verizon.net> - 2011-08-14 15:10 -0400
    Re: confusion about behavior Todd Carnes <toddcarnes@gmail.com> - 2011-08-15 02:04 +0000
      Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-14 19:15 -0700
        Re: confusion about behavior Todd Carnes <toddcarnes@gmail.com> - 2011-08-15 02:34 +0000
      Re: confusion about behavior James Kuyper <jameskuyper@verizon.net> - 2011-08-14 22:37 -0400
    Re: confusion about behavior Todd Carnes <toddcarnes@gmail.com> - 2011-08-15 02:26 +0000

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