Re: [PATCH 01/11] gdb: introduce iterator_range, remove next_adapter

[Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>]

On 2021-07-05 11:41 a.m., Pedro Alves wrote:
> On 2021-06-22 5:56 p.m., Simon Marchi via Gdb-patches wrote:
>> I was always a bit confused by next_adapter, because it kind of mixes
>> the element type and the iterator type.  In reality, it is not much more
>> than a class that wraps two iterators (begin and end).  However, it
>> assumes that:
>>
>>  - you can construct the begin iterator by passing a pointer to the
>>    first element of the iterable
>>  - you can default-construct iterator to make the end iterator
>>
>> I think that by generalizing it a little bit, we can re-use it at more
>> places.
>>
>> Rename it to "iterator_range".  I think it describes a bit better: it's
>> a range made by wrapping a begin and end iterator.  Move it to its own
>> file, since it's not related to next_iterator anymore.
>>
>> iterator_range has two constructors.  The variadic one, where arguments
>> are forwarded to construct the underlying begin iterator.  The end
>> iterator is constructed through default construction.  This is a
>> generalization of what we have today.
>>
>> There is another constructor which receives already constructed begin
>> and end iterators, useful if the end iterator can't be obtained by
>> default-construction.  Or, if you wanted to make a range that does not
>> end at the end of the container, you could pass any iterator as the
>> "end".
>>
>> This generalization allows removing some "range" classes, like
>> all_inferiors_range.  These classes existed only to pass some arguments
>> when constructing the begin iterator.  With iterator_range, those same
>> arguments are passed to the iterator_range constructed and then
>> forwarded to the constructed begin iterator.
>>
>> There is a small functional difference in how iterator_range works
>> compared to next_adapter.  next_adapter stored the pointer it received
>> as argument and constructeur an iterator in the `begin` method.
>> iterator_range constructs the begin iterator and stores it as a member.
>> Its `begin` method returns a copy of that iterator.
>>
>> With just iterator_range, uses of next_adapter<foo> would be replaced
>> with:
>>
>>   using foo_iterator = next_iterator<foo>;
>>   using foo_range = iterator_range<foo_iterator>;
>>
>> However, I added a `next_range` wrapper as a direct replacement for
>> next_adapter<foo>.  IMO, next_range is a slightly better name than
>> next_adapter.
>>
>> The rest of the changes are applications of this new class.
> 
> LGTM.

Thanks, I pushed it by itself, since it's useful on its own.

Simon