Proposal for SentinelInputRange

[Dmitry Olshansky]

28-Feb-2013 19:31, Andrei Alexandrescu пишет:
> On 2/28/13 5:54 AM, Walter Bright wrote:
>> On 2/27/2013 11:55 PM, Jonathan M Davis wrote:
>>>> Again, please see how lexer.c works. I assure you, there is no double
>>>> copying going on, nor is there a double test for the terminating 0.
>>>
>>> I know what the lexer does, and remember that it _doesn't_ operate on
>>> ranges,
>>> and there are subtle differences between being able to just use char*
>>> and
>>> trying to handle generic ranges.
>>
>> Hence the need to invent SentinelInputRange.
>
> I don't think the sentinel input range is a blocker for redoing the
> parser (with ranges) in D. This discussion has probably run its course.


> The right thing to do at this point is port the lexer and figure what
> primitives are necessary from its input.
>

No need to port - look at std.d.lexer again. It was revamped and is 
ready for the new round of review I should say. Let's not use the old 
source for the new module and go the long path of :
split off --> port --> patch up --> D-ify & re-write to ranges

Instead we can just tweak the current std.d.lexer a little bit more and 
we have good clean-room lexer written in the idiomatic D. Well, it's 
getting there w.r.t. idiomaticness but it supports ranges including both 
random-access and forward ones (by transparently specializing for each 
one).
-- 
Dmitry Olshansky