1874892 - Set-Append function for nsTArray

Status: NEW

(Core :: XPCOM, enhancement)

Description

[Vincent Hilla [:vhilla]]

During review of Bug 1830781, we wondered whether a function for set-append would make sense in nsTArray.

Some of these usages of if (!array.Contains(item) { array.AppendElement(item) } could be replaced with something like array.SetAppend(item).

Comment 1

[Robert Longson [:longsonr]]

Is nsTArray the right data structure in the first place? Would a hashmap work better?

Comment 2

[Vincent Hilla [:vhilla]]

I'm sorry, I should clarify that set refers to ordered set. Also see the note there:

Almost all cases on the web platform require an ordered set, instead of an unordered one, since interoperability requires that any developer-exposed enumeration of the set’s contents be consistent between browsers.

Comment 3

[Andrew McCreight [:mccr8]]

As described in the link, by "ordered set" what they really mean is a set where the iteration order is the order the elements were first inserted into the set. They should really call it an "insertion ordered set" or something, as normally I think somebody would assume the ordering would be based on the value of the elements.

Comment 4

[Robert Longson [:longsonr]]

You could use a set and an array. Only insert iterms in the array if they aren't in the set.