Broaden the types of indices that Table.slice supports

[chipkent]

Table.slice() returns subsets of a table's rows based upon the i index of the rows. Slicing is allowed from the beginning or the end of the table.

As discussed in #3110 (comment), we should be supporting slices of the form x[-7:8], where the first slice index is negative, and the second slice index is positive (irstPositionInclusive < 0 && lastPositionExclusive > 0).

The documentation for the following need to be updated.

• Java
• Python

[malhotrashivam]

From what I understand, for the following input,

source = emptyTable(10).update("X=i")  // source = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
result = source.slice(-5, 9)

We should get result as rows [5, 6, 7, 8]

How should we handle a scenario like the following

source = emptyTable(10).update("X=i")  // source = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
result = source.slice(-5, 2)

Should we return an empty set or an exception?

For reference, in the current code, if we run the following

source = emptyTable(10).update("X=i")  // source = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
result = source.slice(7, -5)

We get an empty set []. So should we follow the same convention and return empty set in the slice(-5, 2) case?

[malhotrashivam]

Python also returns an empty set, as shown in the following example

>>> x = list(range(10))     # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> x[7: -5]                # Returns []

So I am keeping the same behavior in our code too.