mmr: added partial mmr

src/merkle/mmr/delta.rs

@@ -0,0 +1,16 @@
+use super::super::{RpoDigest, Vec};
+
+/// Container for the update data of a [PartialMmr]
+#[derive(Debug)]
+pub struct MmrDelta {
+    /// The new version of the [Mmr]
+    pub forest: usize,
+
+    /// Update data.
+    ///
+    /// The data is packed as follows:
+    /// 1. All the elements needed to perform authentication path updates. These are the right
+    ///    siblings required to perform tree merges on the [PartialMmr].
+    /// 2. The new peaks.
+    pub data: Vec<RpoDigest>,
+}