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This commit is contained in:
Grzegorz Świrski 2025-05-03 21:12:57 +02:00
parent e405f58ef5
commit f84a2e5556
1 changed files with 14 additions and 9 deletions
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23
miden-crypto/src/merkle/sparse_path.rs
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@ -89,11 +89,10 @@ impl SparseMerklePath {
return Err(MerkleError::DepthTooBig(node_depth.get().into())); return Err(MerkleError::DepthTooBig(node_depth.get().into()));
} }
let node = if self.is_depth_empty(node_depth) { let node = if let Some(nonempty_index) = self.get_nonempty_index(node_depth) {
*EmptySubtreeRoots::entry(self.depth(), node_depth.get())
} else {
let nonempty_index = self.get_nonempty_index(node_depth);
self.nodes[nonempty_index] self.nodes[nonempty_index]
} else {
*EmptySubtreeRoots::entry(self.depth(), node_depth.get())
}; };
Ok(node) Ok(node)
@ -103,7 +102,7 @@ impl SparseMerklePath {
// ============================================================================================ // ============================================================================================
/// Constructs a borrowing iterator over the nodes in this path. /// Constructs a borrowing iterator over the nodes in this path.
/// Starts from the leaf and iterates toward the root (excluding root). /// Starts from the leaf and iterates toward the root (excluding the root).
pub fn iter(&self) -> impl ExactSizeIterator<Item = RpoDigest> { pub fn iter(&self) -> impl ExactSizeIterator<Item = RpoDigest> {
self.into_iter() self.into_iter()
} }
@ -120,14 +119,20 @@ impl SparseMerklePath {
(self.empty_nodes_mask & Self::bitmask_for_depth(node_depth)) != 0 (self.empty_nodes_mask & Self::bitmask_for_depth(node_depth)) != 0
} }
fn get_nonempty_index(&self, node_depth: NonZero<u8>) -> usize { /// Index of the non-empty node in the `self.nodes` vector. If the specified depth is
/// empty, None is returned.
fn get_nonempty_index(&self, node_depth: NonZero<u8>) -> Option<usize> {
if self.is_depth_empty(node_depth) {
return None;
}
let bit_index = node_depth.get() - 1; let bit_index = node_depth.get() - 1;
let without_shallower = self.empty_nodes_mask >> bit_index; let without_shallower = self.empty_nodes_mask >> bit_index;
let empty_deeper = without_shallower.count_ones() as usize; let empty_deeper = without_shallower.count_ones() as usize;
// The vec index we would use if we didn't have any empty nodes to account for... // The vec index we would use if we didn't have any empty nodes to account for...
let normal_index = (self.depth() - node_depth.get()) as usize; let normal_index = (self.depth() - node_depth.get()) as usize;
// subtracted by the number of empty nodes that are deeper than us. // subtracted by the number of empty nodes that are deeper than us.
normal_index - empty_deeper Some(normal_index - empty_deeper)
} }
} }
@ -198,7 +203,7 @@ impl From<SparseMerklePath> for Vec<RpoDigest> {
// ================================================================================================ // ================================================================================================
/// Iterator for [`SparseMerklePath`]. Starts from the leaf and iterates toward the root (excluding /// Iterator for [`SparseMerklePath`]. Starts from the leaf and iterates toward the root (excluding
/// root). /// the root).
pub struct SparseMerklePathIter<'p> { pub struct SparseMerklePathIter<'p> {
/// The "inner" value we're iterating over. /// The "inner" value we're iterating over.
path: Cow<'p, SparseMerklePath>, path: Cow<'p, SparseMerklePath>,
@ -492,7 +497,7 @@ mod tests {
// Check that we can calculate non-empty indices correctly. // Check that we can calculate non-empty indices correctly.
let control_node = raw_nodes.get(idx).unwrap(); let control_node = raw_nodes.get(idx).unwrap();
assert_eq!( assert_eq!(
sparse_path.get_nonempty_index(NonZero::new(depth).unwrap()), sparse_path.get_nonempty_index(NonZero::new(depth).unwrap()).unwrap(),
nonempty_idx nonempty_idx
); );
let test_node = sparse_path.nodes.get(nonempty_idx).unwrap(); let test_node = sparse_path.nodes.get(nonempty_idx).unwrap();