Add ACursor accumulate functions

Author: mikera

convex-core/src/main/java/convex/lattice/ACursor.java

@@ -1,5 +1,6 @@
 package convex.lattice;
 
+import java.util.function.BinaryOperator;
 import java.util.function.UnaryOperator;
 
 import convex.core.data.ACell;
@@ -46,9 +47,12 @@ public void set(Object o) {
 
 	public abstract V getAndUpdate(UnaryOperator<V> updateFunction);
 
-	
 	public abstract V updateAndGet(UnaryOperator<V> updateFunction);
 
+	public abstract V getAndAccumulate(V x, BinaryOperator<V> accumulatorFunction);
+	
+	public abstract V accumulateAndGet(V x, BinaryOperator<V> accumulatorFunction);
+	
 	public String toString() {
 		V v=get();
 		if (v==null) return "nil";

convex-core/src/main/java/convex/lattice/Root.java

@@ -1,6 +1,7 @@
 package convex.lattice;
 
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.BinaryOperator;
 import java.util.function.UnaryOperator;
 
 import convex.core.data.ACell;
@@ -50,4 +51,14 @@ public V getAndUpdate(UnaryOperator<V> updateFunction) {
 	public V updateAndGet(UnaryOperator<V> updateFunction) {
 		return value.updateAndGet(updateFunction);
 	}
+
+	@Override
+	public V getAndAccumulate(V x, BinaryOperator<V> accumulatorFunction) {
+		return value.getAndAccumulate(x,accumulatorFunction);
+	}
+
+	@Override
+	public V accumulateAndGet(V x, BinaryOperator<V> accumulatorFunction) {
+		return value.accumulateAndGet(x,accumulatorFunction);
+	}
 }

convex-core/src/test/java/convex/lattice/CursorTest.java

@@ -30,5 +30,8 @@ public class CursorTest {
 		assertEquals(TWO,root.getAndUpdate(a->a.inc())); // value is now 3
 		assertCVMEquals(4,root.updateAndGet(a->a.inc())); // value is now 4;
 
+		assertCVMEquals(4,root.getAndAccumulate(CVMLong.ONE,(a,b)->a.add(b))); // value is now 5;
+		assertCVMEquals(7,root.accumulateAndGet(TWO,(a,b)->a.add(b))); // value is now 7;
+
 	}
 }