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use num_bigint::BigUint;
use serde::{Deserialize, Serialize};
use crate::{Actor, Causal, CmRDT, CvRDT, Dot, VClock};
#[derive(Debug, PartialEq, Eq, Clone, Hash, Serialize, Deserialize)]
pub struct GCounter<A: Actor> {
inner: VClock<A>,
}
impl<A: Actor> Default for GCounter<A> {
fn default() -> Self {
Self::new()
}
}
impl<A: Actor> CmRDT for GCounter<A> {
type Op = Dot<A>;
fn apply(&mut self, op: Self::Op) {
self.inner.apply(op)
}
}
impl<A: Actor> CvRDT for GCounter<A> {
fn merge(&mut self, other: Self) {
self.inner.merge(other.inner);
}
}
impl<A: Actor> Causal<A> for GCounter<A> {
fn forget(&mut self, clock: &VClock<A>) {
self.inner.forget(&clock);
}
}
impl<A: Actor> GCounter<A> {
pub fn new() -> Self {
Self {
inner: VClock::new(),
}
}
pub fn inc(&self, actor: A) -> Dot<A> {
self.inner.inc(actor)
}
pub fn read(&self) -> BigUint {
self.inner.iter().map(|dot| dot.counter).sum()
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_basic() {
let mut a = GCounter::new();
let mut b = GCounter::new();
a.apply(a.inc("A"));
b.apply(b.inc("B"));
assert_eq!(a.read(), b.read());
assert_ne!(a, b);
a.apply(a.inc("A"));
assert_eq!(a.read(), b.read() + BigUint::from(1u8));
}
}