From a045b27656fd9dacefa79bff214b3795bee0bf2f Mon Sep 17 00:00:00 2001
From: Dr Maxim Orlovsky <orlovsky@lnp-bp.org>
Date: Tue, 19 Nov 2024 19:35:28 +0100
Subject: [PATCH] merkle: update MerkleLeaves trait with removing lifetime and
 associated iterator type

Signed-off-by: Dr Maxim Orlovsky <orlovsky@lnp-bp.org>
---
 commit_verify/src/merkle.rs | 57 +++++++++----------------------------
 1 file changed, 14 insertions(+), 43 deletions(-)

diff --git a/commit_verify/src/merkle.rs b/commit_verify/src/merkle.rs
index 3e03fe52..bede75b9 100644
--- a/commit_verify/src/merkle.rs
+++ b/commit_verify/src/merkle.rs
@@ -19,8 +19,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use core::{iter, slice};
-use std::collections::{btree_set, BTreeSet};
+use std::collections::BTreeSet;
 use std::ops::SubAssign;
 
 use amplify::confinement::Confined;
@@ -202,77 +201,49 @@ impl MerkleHash {
 
 pub trait MerkleLeaves {
     type Leaf: CommitId<CommitmentId = MerkleHash>;
-    // TODO: Remove associated type
-    type LeafIter<'tmp>: ExactSizeIterator<Item = Self::Leaf>
-    where Self: 'tmp;
-
-    fn merkle_leaves(&self) -> Self::LeafIter<'_>;
+    fn merkle_leaves(&self) -> impl ExactSizeIterator<Item = &Self::Leaf>;
 }
 
 impl<T, const MIN: usize> MerkleLeaves for Confined<Vec<T>, MIN, { u8::MAX as usize }>
-where T: CommitId<CommitmentId = MerkleHash> + Copy
+where T: CommitId<CommitmentId = MerkleHash>
 {
     type Leaf = T;
-    type LeafIter<'tmp>
-        = iter::Copied<slice::Iter<'tmp, T>>
-    where Self: 'tmp;
-
-    fn merkle_leaves(&self) -> Self::LeafIter<'_> { self.iter().copied() }
+    fn merkle_leaves(&self) -> impl ExactSizeIterator<Item = &T> { self.iter() }
 }
 
 impl<T: Ord, const MIN: usize> MerkleLeaves for Confined<BTreeSet<T>, MIN, { u8::MAX as usize }>
-where T: CommitId<CommitmentId = MerkleHash> + Copy
+where T: CommitId<CommitmentId = MerkleHash>
 {
     type Leaf = T;
-    type LeafIter<'tmp>
-        = iter::Copied<btree_set::Iter<'tmp, T>>
-    where Self: 'tmp;
-
-    fn merkle_leaves(&self) -> Self::LeafIter<'_> { self.iter().copied() }
+    fn merkle_leaves(&self) -> impl ExactSizeIterator<Item = &T> { self.iter() }
 }
 
 impl<T, const MIN: usize> MerkleLeaves for Confined<Vec<T>, MIN, { u16::MAX as usize }>
-where T: CommitId<CommitmentId = MerkleHash> + Copy
+where T: CommitId<CommitmentId = MerkleHash>
 {
     type Leaf = T;
-    type LeafIter<'tmp>
-        = iter::Copied<slice::Iter<'tmp, T>>
-    where Self: 'tmp;
-
-    fn merkle_leaves(&self) -> Self::LeafIter<'_> { self.iter().copied() }
+    fn merkle_leaves(&self) -> impl ExactSizeIterator<Item = &T> { self.iter() }
 }
 
 impl<T: Ord, const MIN: usize> MerkleLeaves for Confined<BTreeSet<T>, MIN, { u16::MAX as usize }>
-where T: CommitId<CommitmentId = MerkleHash> + Copy
+where T: CommitId<CommitmentId = MerkleHash>
 {
     type Leaf = T;
-    type LeafIter<'tmp>
-        = iter::Copied<btree_set::Iter<'tmp, T>>
-    where Self: 'tmp;
-
-    fn merkle_leaves(&self) -> Self::LeafIter<'_> { self.iter().copied() }
+    fn merkle_leaves(&self) -> impl ExactSizeIterator<Item = &T> { self.iter() }
 }
 
 impl<T, const MIN: usize> MerkleLeaves for Confined<Vec<T>, MIN, { u32::MAX as usize }>
-where T: CommitId<CommitmentId = MerkleHash> + Copy
+where T: CommitId<CommitmentId = MerkleHash>
 {
     type Leaf = T;
-    type LeafIter<'tmp>
-        = iter::Copied<slice::Iter<'tmp, T>>
-    where Self: 'tmp;
-
-    fn merkle_leaves(&self) -> Self::LeafIter<'_> { self.iter().copied() }
+    fn merkle_leaves(&self) -> impl ExactSizeIterator<Item = &T> { self.iter() }
 }
 
 impl<T: Ord, const MIN: usize> MerkleLeaves for Confined<BTreeSet<T>, MIN, { u32::MAX as usize }>
-where T: CommitId<CommitmentId = MerkleHash> + Copy
+where T: CommitId<CommitmentId = MerkleHash>
 {
     type Leaf = T;
-    type LeafIter<'tmp>
-        = iter::Copied<btree_set::Iter<'tmp, T>>
-    where Self: 'tmp;
-
-    fn merkle_leaves(&self) -> Self::LeafIter<'_> { self.iter().copied() }
+    fn merkle_leaves(&self) -> impl ExactSizeIterator<Item = &T> { self.iter() }
 }
 
 /// Helper struct to track depth when working with Merkle blocks.