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// Copyright (C) 2024 The Software Heritage developers
// See the AUTHORS file at the top-level directory of this distribution
// License: GNU General Public License version 3, or any later version
// See top-level LICENSE file for more information
use chrono::prelude::*;
use lazy_static::lazy_static;
lazy_static! {
static ref MAX_YEAR: i32 = Utc::now().year();
}
/// Compact representation of a set of years
///
/// Only the current year and the last 63 are supported, others are ignored
///
/// ```
/// # use std::collections::HashSet;
/// # use swh_graph_contributions::YearSet;
///
/// let mut set = YearSet::default();
/// set.insert_timestamp_year(1713967146); // 2024-04-24
/// set.insert_timestamp_year(1666019057); // 2022-10-17
/// set.insert_timestamp_year(-1713967146); // 1915-09-09
///
/// assert_eq!(set.iter().collect::<HashSet<_>>(), vec![2022, 2024].into_iter().collect());
/// ```
#[derive(Clone, Default, Eq, PartialEq)]
pub struct YearSet(
u64, // Bitfield, current year is the lowest bit, 63 years ago is the highest
);
impl YearSet {
pub fn insert_timestamp_year(&mut self, timestamp: i64) {
self.0 |= Self::mask_for_timestamp(timestamp)
}
pub fn max_year() -> i32 {
*MAX_YEAR
}
pub fn min_year() -> i32 {
*MAX_YEAR - 63
}
fn mask_for_timestamp(timestamp: i64) -> u64 {
let Some(date) = DateTime::<Utc>::from_timestamp(timestamp, 0) else {
return 0;
};
let year = date.year();
if year < Self::min_year() || year > Self::max_year() {
0
} else {
1 << (Self::max_year() - year)
}
}
/// Adds all entries from another `YearSet`.
pub fn merge(&mut self, other: &Self) {
self.0 |= other.0
}
/// Returns years (as Gregorian calendar years) contained in this set
pub fn iter(&self) -> impl Iterator<Item = i32> + '_ {
(0..64)
.rev()
.filter(|offset| (self.0 & (1 << offset)) != 0)
.map(|offset| Self::max_year() - offset)
}
}