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//! Contains node definitions for Merkle trees, including leaf and internal node structures.
use crate::hasher::Hasher;
/// Enum representing the type of a Merkle tree node.
#[derive(Debug, Clone)]
pub enum NodeType {
/// A leaf node that contains no children.
Leaf,
/// An internal node that has two children.
Internal(Box<Node>, Box<Node>),
}
impl NodeType {
/// Returns a reference to the left child if the node is internal.
pub fn left(&self) -> Option<&Node> {
match self {
NodeType::Leaf => None,
NodeType::Internal(l, _) => Some(l),
}
}
/// Returns a reference to the right child if the node is internal.
pub fn right(&self) -> Option<&Node> {
match self {
NodeType::Leaf => None,
NodeType::Internal(_, r) => Some(r),
}
}
}
/// Represents a node in a Merkle tree, either leaf or internal.
#[derive(Debug, Clone)]
pub struct Node {
/// Hash value stored at the node.
hash: String,
/// Type of the node: leaf or internal.
kind: NodeType,
}
impl Node {
/// Constructs a new leaf node from input data.
///
/// # Arguments
///
/// * `hasher` - A reference to a hashing strategy.
/// * `data` - The data to be hashed and stored as a leaf.
pub fn new_leaf<T: ToString>(hasher: &dyn Hasher, data: T) -> Self {
let hash = hasher.hash(&data.to_string());
Self {
hash,
kind: NodeType::Leaf,
}
}
/// Constructs a new internal node from two child nodes.
///
/// # Arguments
///
/// * `hasher` - A reference to a hashing strategy.
/// * `left` - Left child node.
/// * `right` - Right child node.
///
/// # Behavior
///
/// The internal node hash is computed as the hash of the concatenated children's hashes.
pub fn new_internal(hasher: &dyn Hasher, left: Node, right: Node) -> Self {
let combined = format!("{}{}", left.hash, right.hash);
let hash = hasher.hash(&combined);
Self {
hash,
kind: NodeType::Internal(Box::new(left), Box::new(right)),
}
}
/// Returns a reference to the hash of the node.
pub fn hash(&self) -> &str {
&self.hash
}
/// Returns a reference to the node's type (leaf or internal).
pub fn kind(&self) -> &NodeType {
&self.kind
}
}
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