RangeMap is a map data structure whose keys are stored as ranges. Contiguous and overlapping ranges that map to the same value are coalesced into a single range.
A corresponding RangeSet structure is also provided.
use chrono::offset::TimeZone;
use chrono::{Duration, Utc};
use rangemap::RangeMap;
fn main() {
let people = ["Alice", "Bob", "Carol"];
let mut roster = RangeMap::new();
// Set up initial roster.
let start_of_roster = Utc.ymd(2019, 1, 7);
let mut week_start = start_of_roster;
for _ in 0..3 {
for person in &people {
let next_week = week_start + Duration::weeks(1);
roster.insert(week_start..next_week, person);
week_start = next_week;
}
}
// Bob is covering Alice's second shift (the fourth shift overall).
let fourth_shift_start = start_of_roster + Duration::weeks(3);
let fourth_shift_end = fourth_shift_start + Duration::weeks(1);
roster.insert(fourth_shift_start..fourth_shift_end, &"Bob");
for (range, person) in roster.iter() {
println!("{} ({}): {}", range.start, range.end - range.start, person);
}
// Output:
// 2019-01-07UTC (P7D): Alice
// 2019-01-14UTC (P7D): Bob
// 2019-01-21UTC (P7D): Carol
// 2019-01-28UTC (P14D): Bob
// 2019-02-11UTC (P7D): Carol
// 2019-02-18UTC (P7D): Alice
// 2019-02-25UTC (P7D): Bob
// 2019-03-04UTC (P7D): Carol
}