I'm creating a List data structure in PHP based off of the WHATWG Infra Standard as a programming exercise and am having some issues trying to clarify a couple items.
- I don't see anywhere that implies that indices in a list must be consecutive. However, it seems to be implied in the definition of getting the indices of a list:
To get the indices of a list, return the range from 0 to the list’s size, exclusive.
- In the definition of getting the indices (listed above) it says to return the range from 0 to the list's size, but wouldn't this include one extra index than is actually present? I see the sentence ends with ", exclusive" but I don't know what that means in this context.
Any insight is much appreciated!
CodePudding user response：
There is no operation that would allow for a "sparse" list if that's what you are asking for.
Removing items from a list will make the following items "move" to fill the now empty positions.
And regarding "return the range from 0 to the list’s size, exclusive." "range" is a link to https://infra.spec.whatwg.org/#the-exclusive-range, which states
The range n to m, exclusive, creates a new ordered set containing all of the integers from n up to and including m − 1 in consecutively increasing order, as long as m is greater than n. If m equals n, then it creates an empty ordered set.
Don't be afraid of following all the links in the specs if you want to implement it.