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

[Pedro Alves <pedro@palves.net>]

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.