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use std::cmp::{Ordering};
use rustc_serialize::{Encodable, Decodable};
use super::VClock;
#[derive(Debug, Eq, Clone, Hash, RustcEncodable, RustcDecodable)]
pub struct GCounter<A: Ord + Clone + Encodable + Decodable> {
inner: VClock<A>
}
impl<A: Ord + Clone + Encodable + Decodable> Ord for GCounter<A> {
fn cmp(&self, other: &GCounter<A>) -> Ordering {
let (c, oc) = (self.value(), other.value());
c.cmp(&oc)
}
}
impl<A: Ord + Clone + Encodable + Decodable> PartialOrd for GCounter<A> {
fn partial_cmp(&self, other: &GCounter<A>) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl<A: Ord + Clone + Encodable + Decodable> PartialEq for GCounter<A> {
fn eq(&self, other: &GCounter<A>) -> bool {
let (c, oc) = (self.value(), other.value());
c == oc
}
}
impl<A: Ord + Clone + Encodable + Decodable> GCounter<A> {
pub fn new() -> GCounter<A> {
GCounter {
inner: VClock::new()
}
}
pub fn increment(&mut self, actor: A) {
self.inner.increment(actor);
}
pub fn value(&self) -> u64 {
self.inner.dots.values().fold(0, |acc, count| acc + count)
}
pub fn merge(&mut self, other: GCounter<A>) {
self.inner.merge(other.inner);
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_basic() {
let (mut a, mut b) = (GCounter::new(), GCounter::new());
a.increment("A".to_string());
b.increment("B".to_string());
assert_eq!(a.value(), b.value());
assert!(a == b);
a.increment("A".to_string());
assert!(a > b);
}
}