Proposal for SentinelInputRange

[Dmitry Olshansky]

28-Feb-2013 22:08, Timon Gehr пишет:
> On 02/28/2013 05:48 PM, Dmitry Olshansky wrote:
>> ...
>>
>> line 300:
>>      case 0x1A:          // ^Z means end of file
>>      case 0:
>>                          break;
>>
>> On the lines you noted it claimed that that 0x1a is outdate. Along with
>> the fact that you allocate filesize+2 and fill the last 2 bytes with
>> zeros.
>>
>> In any case I see 0 and 0x1a as 2 values that act like sentinels i.e. a
>> tuple. And this is what spec says - any one of them is a sentinel.
>> Correct me if I'm wrong.
>>
>
> A sentinel is some data the original data is augmented with in order to
> simplify its processing.

I thought 0 was proposed as such. Might have misunderstood the proposition.

> The lexer acts the same on 0x1A and 0, but only the additional 0 at the
> end which does not occur in the input is the sentinel.


That would mean that when you see 0 or 0x1A you do a check to see if 
that's the end of input then decide it's really the end of input.

If that's the intended behavior I fail to decipher it from  here:
http://dlang.org/lex.html#EndOfFile

> The lexer may
> even encounter a 0 that is not a sentinel.


-- 
Dmitry Olshansky