pass cursor as pointer

Author: James Cor

go/store/prolly/tree/map.go

@@ -240,7 +240,8 @@ func (t StaticMap[K, V, O]) WalkNodes(ctx context.Context, cb NodeCb) error {
 }
 
 func (t StaticMap[K, V, O]) Get(ctx context.Context, query K, cb KeyValueFn[K, V]) (err error) {
-	cur, err := newLeafCursorAtKey(ctx, t.NodeStore, t.Root, query, t.Order)
+	cur := &cursor{nd: t.Root, nrw: t.NodeStore}
+	err = moveCursorToKey(ctx, cur, query, t.Order)
 	if err != nil {
 		return err
 	}
@@ -260,7 +261,8 @@ func (t StaticMap[K, V, O]) Get(ctx context.Context, query K, cb KeyValueFn[K, V
 }
 
 func (t StaticMap[K, V, O]) GetPrefix(ctx context.Context, query K, prefixOrder O, cb KeyValueFn[K, V]) (err error) {
-	cur, err := newLeafCursorAtKey(ctx, t.NodeStore, t.Root, query, prefixOrder)
+	cur := &cursor{nd: t.Root, nrw: t.NodeStore}
+	err = moveCursorToKey(ctx, cur, query, prefixOrder)
 	if err != nil {
 		return err
 	}
@@ -280,7 +282,8 @@ func (t StaticMap[K, V, O]) GetPrefix(ctx context.Context, query K, prefixOrder
 }
 
 func (t StaticMap[K, V, O]) Has(ctx context.Context, query K) (ok bool, err error) {
-	cur, err := newLeafCursorAtKey(ctx, t.NodeStore, t.Root, query, t.Order)
+	cur := &cursor{nd: t.Root, nrw: t.NodeStore}
+	err = moveCursorToKey(ctx, cur, query, t.Order)
 	if err != nil {
 		return false, err
 	} else if cur.Valid() {
@@ -290,7 +293,8 @@ func (t StaticMap[K, V, O]) Has(ctx context.Context, query K) (ok bool, err erro
 }
 
 func (t StaticMap[K, V, O]) HasPrefix(ctx context.Context, query K, prefixOrder O) (ok bool, err error) {
-	cur, err := newLeafCursorAtKey(ctx, t.NodeStore, t.Root, query, prefixOrder)
+	cur := &cursor{nd: t.Root, nrw: t.NodeStore}
+	err = moveCursorToKey(ctx, cur, query, prefixOrder)
 	if err != nil {
 		return false, err
 	} else if cur.Valid() {

go/store/prolly/tree/node_cursor.go

@@ -183,9 +183,8 @@ func newCursorFromSearchFn(ctx context.Context, ns NodeStore, nd *Node, search S
 	return
 }
 
-func newLeafCursorAtKey[K ~[]byte, O Ordering[K]](ctx context.Context, ns NodeStore, nd *Node, key K, order O) (cursor, error) {
+func moveCursorToKey[K ~[]byte, O Ordering[K]](ctx context.Context, cur *cursor, key K, order O) error {
 	var err error
-	cur := cursor{nd: nd, nrw: ns}
 	for {
 		// binary search |cur.nd| for |key|
 		i, j := 0, cur.nd.Count()
@@ -208,12 +207,12 @@ func newLeafCursorAtKey[K ~[]byte, O Ordering[K]](ctx context.Context, ns NodeSt
 		cur.keepInBounds()
 
 		// reuse |cur| object to keep stack alloc'd
-		cur.nd, err = fetchChild(ctx, ns, cur.currentRef())
+		cur.nd, err = fetchChild(ctx, cur.nrw, cur.currentRef())
 		if err != nil {
-			return cur, err
+			return err
 		}
 	}
-	return cur, nil
+	return nil
 }
 
 // searchForKey returns a SearchFn for |key|.