std: add std.ArrayList.remove

[daurnimator]

Closes #2247

Required for a sensible http headers object.

[andrewrk]

I'm on board with adding this function, but since it has an important caveat of O(N) performance, I'd like to request the following changes:

• a name that makes it sound like not one of the "main" operations of ArrayList. For example removeElementByShifting. I'm open to other names as well.
• add documentation comments for the function mentioning O(N) and explaining how the function is implemented.

[daurnimator]

I was thinking that it would be good if zig container types all had the same API (for operations they support), with big-O behaviour documented in e.g. a table. Similar to C++

.remove is already supported by

• hash_map
• priority_queue
• rb
• linked_list
• atomic/queue

[andrewrk]

I was thinking that it would be good if zig container types all had the same API (for operations they support)

Please take this question earnestly - I'm not trying to be condescending - can you explain this reasoning? Other than a vague sense of tidiness that one gets from cleaning their room.

[vgmind]

I guess being explicit here is important as there is more than one valid way to remove an element from an ArrayList. There's the shift method being implement here that has certain run time characteristics that people with large arrays may not like but keeps the original order. Then there is the swap with the last element and just decrease the size, not great if you need to keep your Array list ordered but has constant performance characteristics.

[Tetralux]

See #2247 (comment).

[andrewrk]

@daurnimator you good with orderedRemove?

[daurnimator]

@daurnimator you good with orderedRemove?

I'm okay with it; I'd still like to call it .remove, I've been meaning to do a write up on why; though we can make a new issue for that if we can merge this now?