Make MerkleBuoy generic utility

commit_verify/src/merkle.rs

@@ -22,6 +22,7 @@
 use core::{iter, slice};
 use std::collections::{btree_set, BTreeSet};
 use std::io::Write;
+use std::ops::SubAssign;
 
 use amplify::confinement::Confined;
 use amplify::num::u5;
@@ -202,3 +203,60 @@ where T: CommitmentId<Id = MerkleNode> + Copy
 
     fn merkle_leaves(&self) -> Self::LeafIter<'_> { self.iter().copied() }
 }
+
+/// Helper struct to track depth when working with Merkle blocks.
+// TODO: v0.11 Remove default generic from MerkleBuoy
+#[derive(Clone, PartialEq, Eq, Debug, Default)]
+pub struct MerkleBuoy<D: Copy + Eq + SubAssign<u8> + Default = u5> {
+    buoy: D,
+    stack: Option<Box<MerkleBuoy<D>>>,
+}
+
+impl<D: Copy + Eq + SubAssign<u8> + Default> MerkleBuoy<D> {
+    pub fn new(top: D) -> Self {
+        Self {
+            buoy: top,
+            stack: None,
+        }
+    }
+
+    /// Measure the current buoy level.
+    pub fn level(&self) -> D {
+        self.stack
+            .as_ref()
+            .map(Box::as_ref)
+            .map(MerkleBuoy::level)
+            .unwrap_or(self.buoy)
+    }
+
+    /// Add new item to the buoy.
+    ///
+    /// Returns whether the buoy have surfaced in a result.
+    ///
+    /// The buoy surfaces each time the contents it has is reduced to two depth
+    /// of the same level.
+    pub fn push(&mut self, depth: D) -> bool {
+        if depth == D::default() {
+            return false;
+        }
+        match self
+            .stack
+            .as_mut()
+            .map(|stack| (stack.push(depth), stack.level()))
+        {
+            None if depth == self.buoy => {
+                self.buoy -= 1;
+                true
+            }
+            None => {
+                self.stack = Some(Box::new(MerkleBuoy::new(depth)));
+                false
+            }
+            Some((true, level)) => {
+                self.stack = None;
+                self.push(level)
+            }
+            Some((false, _)) => false,
+        }
+    }
+}

commit_verify/src/mpc/atoms.rs

@@ -170,58 +170,3 @@ impl Default for MultiSource {
         }
     }
 }
-
-/// Helper struct to track depth when merging two merkle blocks.
-pub struct MerkleBuoy {
-    buoy: u5,
-    stack: Option<Box<MerkleBuoy>>,
-}
-
-impl MerkleBuoy {
-    pub fn new(top: u5) -> Self {
-        Self {
-            buoy: top,
-            stack: None,
-        }
-    }
-
-    /// Measure the current buoy level.
-    pub fn level(&self) -> u5 {
-        self.stack
-            .as_ref()
-            .map(Box::as_ref)
-            .map(MerkleBuoy::level)
-            .unwrap_or(self.buoy)
-    }
-
-    /// Add new item to the buoy.
-    ///
-    /// Returns whether the buoy have surfaced in a result.
-    ///
-    /// The buoy surfaces each time the contents it has is reduced to two depth
-    /// of the same level.
-    pub fn push(&mut self, depth: u5) -> bool {
-        if depth == u5::ZERO {
-            return false;
-        }
-        match self
-            .stack
-            .as_mut()
-            .map(|stack| (stack.push(depth), stack.level()))
-        {
-            None if depth == self.buoy => {
-                self.buoy -= 1;
-                true
-            }
-            None => {
-                self.stack = Some(Box::new(MerkleBuoy::new(depth)));
-                false
-            }
-            Some((true, level)) => {
-                self.stack = None;
-                self.push(level)
-            }
-            Some((false, _)) => false,
-        }
-    }
-}

commit_verify/src/mpc/block.rs

@@ -29,11 +29,11 @@ use amplify::num::u5;
 use strict_encoding::StrictEncode;
 
 use crate::id::CommitmentId;
-use crate::merkle::MerkleNode;
+use crate::merkle::{MerkleBuoy, MerkleNode};
 use crate::mpc::atoms::Leaf;
 use crate::mpc::tree::protocol_id_pos;
 use crate::mpc::{
-    Commitment, MerkleBuoy, MerkleTree, Message, MessageMap, Proof, ProtocolId, MERKLE_LNPBP4_TAG,
+    Commitment, MerkleTree, Message, MessageMap, Proof, ProtocolId, MERKLE_LNPBP4_TAG,
 };
 use crate::{Conceal, LIB_NAME_COMMIT_VERIFY};
 
@@ -430,7 +430,7 @@ impl MerkleBlock {
                 }
                 Ordering::Less => {
                     cross_section.push(n2);
-                    let mut buoy = MerkleBuoy::new(n2_depth);
+                    let mut buoy = MerkleBuoy::<u5>::new(n2_depth);
                     let mut stop = false;
                     last_b = None;
                     cross_section.extend(b.by_ref().take_while(|n| {
@@ -448,7 +448,7 @@ impl MerkleBlock {
                 }
                 Ordering::Greater => {
                     cross_section.push(n1);
-                    let mut buoy = MerkleBuoy::new(n1_depth);
+                    let mut buoy = MerkleBuoy::<u5>::new(n1_depth);
                     let mut stop = false;
                     last_a = None;
                     cross_section.extend(a.by_ref().take_while(|n| {

commit_verify/src/mpc/mod.rs

@@ -27,12 +27,15 @@ mod atoms;
 mod tree;
 mod block;
 
-pub use atoms::{Commitment, Leaf, MerkleBuoy, Message, MessageMap, MultiSource, ProtocolId};
+pub use atoms::{Commitment, Leaf, Message, MessageMap, MultiSource, ProtocolId};
 pub use block::{InvalidProof, LeafNotKnown, MergeError, MerkleBlock, MerkleProof};
 #[cfg(feature = "rand")]
 pub use tree::Error;
 pub use tree::MerkleTree;
 
+#[deprecated(since = "0.10.6", note = "use commit_verify::merkle::MerkleBuoy instead")]
+pub use crate::merkle::MerkleBuoy;
+
 pub const MERKLE_LNPBP4_TAG: u128 = u128::from_le_bytes(*b"urn:lnpbp:lnpbp4");
 
 /// Marker trait for variates of LNPBP-4 commitment proofs, which differ by the