Sparse Merkle tree

A sparse Merkle tree implementation that only recomputes its branches’ hashes when asked.

Example

```rust use sp4r53::{blake3, Proof, Tree};

let foo = blake3::hash(b"foo"); let bar = blake3::hash(b"bar"); let baz = blake3::hash(b"baz");

let mut tree = Tree::new();

tree.insert(foo); tree.insert(bar); tree.insert(baz); asserteq!(tree.isvalid(), false);

let root = tree.flush(); asserteq!(tree.isvalid(), true); assert_eq!(tree.root(), Some(root));

let proof = tree.proove(&[foo, baz]).unwrap(); assert_eq!(proof.verify(root), true);

let encoded = proof.asbytes(); let decoded = Proof::frombytes(&encoded).unwrap(); assert_eq!(decoded, proof);

tree.remove(bar);

let root = tree.flush(); assert_eq!(proof.verify(root), false); ```

License

This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.