Integrated: 8304759: Add BitMap iterators

[Kim Barrett]

On Sat, 25 Mar 2023 15:43:29 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

> Please review this change which adds iteration over the set bit positions of a
> BitMap via an iterator object.  This is in addition to the existing iterate()
> and reverse_iterate() functions that apply a function to the set bit positions.
> 
> There are two iterator classes: BitMap::Iterator and BitMap::ReverseIterator.
> Iteration uses a single, self-contained iterator object, rather than a pair of
> iterator objects as is done with standard library iterators.  This is because
> the desired form of iteration over bitmaps doesn't lend itself well to the
> begin/end pair style.  Typical usage is something like
> 
> 
> for (BitMap::Iterator it{map, beg, end}; !it.is_empty(); it.step()) {
>   ... use it.index()
> }
> 
> 
> However, as a syntactic convenience, these iterator classes provide begin()
> and end() member functions returning objects supporting the requirements for
> range-based for loops.  By constraining these objects to this usage we can
> cope with the "iterator pair" requirements.  Usage is something like
> 
> 
> for (BitMap::idx_t index : BitMap::Iterator{map, beg, end}) {
>   ...
> }
> 
> 
> Testing:
> mach5 tier1, which includes running the updated gtests on all Oracle-supported
> platforms.

This pull request has now been integrated.

Changeset: 34f4d7f4
Author:    Kim Barrett <kbarrett at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/34f4d7f4ad388d8264225c2aefe048ca9a42cfa2
Stats:     381 lines in 4 files changed: 381 ins; 0 del; 0 mod

8304759: Add BitMap iterators

Reviewed-by: stefank, aboldtch, tschatzl

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PR: https://git.openjdk.org/jdk/pull/13184