Proposal for SentinelInputRange

Walter Bright newshound2 at digitalmars.com
Thu Feb 28 08:43:06 PST 2013


On 2/28/2013 6:59 AM, Andrei Alexandrescu wrote:
> On 2/28/13 2:37 AM, deadalnix wrote:
>> I don't see how defining a specific sentinel range here helps.
>
> On first blush I agree. It may as well be a range that by convention is
> sentinel-terminated, and there's calls to front and popFront but never to empty.


Consider the following code from lexer.c:

    p++;
    switch (*p)

Written using an InputRange:

    popFront();
    switch (front)

That code is INVALID. This is why a SentinelInputRange is necessary. You can't 
just use an InputRange in an invalid manner by convention.



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