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combine from_sized_iter and from_iter_with_depth methods

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Grzegorz Świrski 2025-05-03 20:36:22 +02:00
parent 8374e07c4a
commit 5557a89538
1 changed files with 21 additions and 38 deletions
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59
miden-crypto/src/merkle/sparse_path.rs
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@ -47,9 +47,27 @@ impl SparseMerklePath {
I: IntoIterator<IntoIter: ExactSizeIterator, Item = RpoDigest>, I: IntoIterator<IntoIter: ExactSizeIterator, Item = RpoDigest>,
{ {
let iterator = iterator.into_iter(); let iterator = iterator.into_iter();
// `iterator.len() as u8` will truncate, but not below `SMT_MAX_DEPTH`, which let tree_depth = iterator.len() as u8;
// `from_iter_with_depth` checks for.
Self::from_iter_with_depth(iterator.len() as u8, iterator) if tree_depth > SMT_MAX_DEPTH {
return Err(MerkleError::DepthTooBig(tree_depth as u64));
}
let mut empty_nodes_mask: u64 = 0;
let mut nodes: Vec<RpoDigest> = Default::default();
for (depth, node) in iter::zip(path_depth_iter(tree_depth), iterator) {
let &equivalent_empty_node = EmptySubtreeRoots::entry(tree_depth, depth.get());
let is_empty = node == equivalent_empty_node;
let node = if is_empty { None } else { Some(node) };
match node {
Some(node) => nodes.push(node),
None => empty_nodes_mask |= Self::bitmask_for_depth(depth),
}
}
Ok(SparseMerklePath { nodes, empty_nodes_mask })
} }
/// Returns the total depth of this path, i.e., the number of nodes this path represents. /// Returns the total depth of this path, i.e., the number of nodes this path represents.
@ -114,41 +132,6 @@ impl SparseMerklePath {
// PRIVATE HELPERS // PRIVATE HELPERS
// ============================================================================================ // ============================================================================================
/// Constructs a sparse Merkle path from a manually specified tree depth, and an iterator over
/// Merkle nodes from deepest to shallowest.
///
/// Knowing the size is necessary to calculate the depth of the tree, which is needed to detect
/// which nodes are empty nodes.
///
/// Warning: this method does not check if the iterator contained more elements.
///
/// # Errors
/// Returns [MerkleError::DepthTooBig] if `tree_depth` is greater than [SMT_MAX_DEPTH].
fn from_iter_with_depth(
tree_depth: u8,
iter: impl IntoIterator<Item = RpoDigest>,
) -> Result<Self, MerkleError> {
if tree_depth > SMT_MAX_DEPTH {
return Err(MerkleError::DepthTooBig(tree_depth as u64));
}
let mut empty_nodes_mask: u64 = 0;
let mut nodes: Vec<RpoDigest> = Default::default();
for (depth, node) in iter::zip(path_depth_iter(tree_depth), iter) {
let &equivalent_empty_node = EmptySubtreeRoots::entry(tree_depth, depth.get());
let is_empty = node == equivalent_empty_node;
let node = if is_empty { None } else { Some(node) };
match node {
Some(node) => nodes.push(node),
None => empty_nodes_mask |= Self::bitmask_for_depth(depth),
}
}
Ok(SparseMerklePath { nodes, empty_nodes_mask })
}
const fn bitmask_for_depth(node_depth: NonZero<u8>) -> u64 { const fn bitmask_for_depth(node_depth: NonZero<u8>) -> u64 {
// - 1 because paths do not include the root. // - 1 because paths do not include the root.
1 << (node_depth.get() - 1) 1 << (node_depth.get() - 1)