Add Subtract-on-Evict (SoE)

Author: segeljakt

rust/src/lib.rs

@@ -43,3 +43,6 @@ where
 
 /// Recalculate-From-Scratch
 pub mod recalc;
+
+/// Subtract-On-Evict
+pub mod soe;

rust/src/soe/mod.rs

@@ -0,0 +1,42 @@
+use crate::FifoWindow;
+use alga::general::AbstractGroup;
+use alga::general::Operator;
+use std::collections::VecDeque;
+use std::marker::PhantomData;
+
+#[derive(Debug)]
+pub struct SoE<Value, BinOp>
+where
+    Value: AbstractGroup<BinOp> + Clone,
+    BinOp: Operator,
+{
+    stack: VecDeque<Value>,
+    agg: Value,
+    op: PhantomData<BinOp>,
+}
+
+impl<Value, BinOp> FifoWindow<Value, BinOp> for SoE<Value, BinOp>
+where
+    Value: AbstractGroup<BinOp> + Clone,
+    BinOp: Operator,
+{
+    fn new() -> SoE<Value, BinOp> {
+        SoE {
+            stack: VecDeque::new(),
+            agg: Value::identity(),
+            op: PhantomData,
+        }
+    }
+    fn push(&mut self, v: Value) {
+        self.agg = self.agg.operate(&v);
+        self.stack.push_back(v);
+    }
+    fn pop(&mut self) {
+        if let Some(top) = self.stack.pop_front() {
+            self.agg = self.agg.operate(&top.two_sided_inverse());
+        }
+    }
+    fn query(&self) -> Value {
+        self.agg.clone()
+    }
+}

rust/tests/fifo-window.rs

@@ -9,6 +9,7 @@ use alga::general::Operator;
 use alga::general::TwoSidedInverse;
 use rand::Rng;
 use swag::recalc::*;
+use swag::soe::*;
 use swag::*;
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
@@ -100,3 +101,13 @@ fn test1_recalc() {
 fn test2_recalc() {
     test2::<ReCalc<Value, Sum>>();
 }
+
+#[test]
+fn test1_soe() {
+    test1::<SoE<Value, Sum>>();
+}
+
+#[test]
+fn test2_soe() {
+    test2::<SoE<Value, Sum>>();
+}