find_physical_length

A RunEndEncodedArray.

Find the physical length of this array.

The physical length of an run-end encoded array is the number of physical values (and run-ends) necessary to represent the logical range of values from offset to length.

Avoid calling this function if the physical length can be established in some other way (e.g. when iterating over the runs sequentially until the end). This function uses binary-search, so it has a O(log N) cost.