Module indices 

Parser and resolver for the --indices flag.

Grammar:

indices := expr ("," expr)*
expr    := int | range
range   := int? ":" int?
int     := "-"? [0-9]+

Resolution against a dataset with rowcount rows:

• Negative i means rowcount + i (errors if still < 0).
• a:b is inclusive on both ends.
• a: means a..=rowcount-1.
• :b means 0..=b.
• : means the entire dataset.
• Order is preserved and duplicates are not removed.

Functions

resolve

Parse --indices and expand against the dataset row count.