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use hash::{Hashable, Algorithm};
use proof::Proof;
use std::iter::FromIterator;
use std::marker::PhantomData;
use std::ops;
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct MerkleTree<T: Ord + Clone + AsRef<[u8]>, A: Algorithm<T>> {
data: Vec<T>,
leafs: usize,
height: usize,
_a: PhantomData<A>,
}
impl<T: Ord + Clone + AsRef<[u8]>, A: Algorithm<T>> MerkleTree<T, A> {
pub fn new<I: IntoIterator<Item = T>>(data: I) -> MerkleTree<T, A> {
Self::from_iter(data)
}
pub fn from_data<O: Hashable<A>, I: IntoIterator<Item = O>>(data: I) -> MerkleTree<T, A> {
let mut a = A::default();
Self::from_iter(data.into_iter().map(|x| {
a.reset();
x.hash(&mut a);
a.hash()
}))
}
fn build(&mut self) {
let mut a = A::default();
let mut width = self.leafs;
let mut i: usize = 0;
let mut j: usize = width;
while width > 1 {
if width & 1 == 1 {
let he = self.data[self.len() - 1].clone();
self.data.push(he);
width += 1;
j += 1;
}
while i < j {
a.reset();
let h = a.node(self.data[i].clone(), self.data[i + 1].clone());
self.data.push(h);
i += 2;
}
width >>= 1;
j += width;
}
}
pub fn gen_proof(&self, i: usize) -> Proof<T> {
assert!(i < self.leafs);
let mut lemma: Vec<T> = Vec::with_capacity(self.height + 1);
let mut path: Vec<bool> = Vec::with_capacity(self.height - 1);
let mut base = 0;
let mut j = i;
let mut width = self.leafs;
if width & 1 == 1 {
width += 1;
}
lemma.push(self.data[j].clone());
while base + 1 < self.len() {
lemma.push(if j & 1 == 0 {
self.data[base + j + 1].clone()
} else {
self.data[base + j - 1].clone()
});
path.push(j & 1 == 0);
base += width;
width >>= 1;
if width & 1 == 1 {
width += 1;
}
j >>= 1;
}
lemma.push(self.root());
Proof::new(lemma, path)
}
pub fn root(&self) -> T {
self.data[self.data.len() - 1].clone()
}
pub fn len(&self) -> usize {
self.data.len()
}
pub fn is_empty(&self) -> bool {
self.data.is_empty()
}
pub fn height(&self) -> usize {
self.height
}
pub fn leafs(&self) -> usize {
self.leafs
}
pub fn as_slice(&self) -> &[T] {
self
}
}
impl<T: Ord + Clone + AsRef<[u8]>, A: Algorithm<T>> FromIterator<T> for MerkleTree<T, A> {
fn from_iter<I: IntoIterator<Item = T>>(into: I) -> Self {
let iter = into.into_iter();
let mut data: Vec<T> = match iter.size_hint().1 {
Some(e) => {
let pow = next_pow2(e);
let size = 2 * pow - 1;
Vec::with_capacity(size)
}
None => Vec::new(),
};
let mut a = A::default();
for item in iter {
a.reset();
data.push(a.leaf(item));
}
let leafs = data.len();
let pow = next_pow2(leafs);
let size = 2 * pow - 1;
assert!(leafs > 1);
let mut mt: MerkleTree<T, A> = MerkleTree {
data,
leafs,
height: log2_pow2(size + 1),
_a: PhantomData,
};
mt.build();
mt
}
}
impl<T: Ord + Clone + AsRef<[u8]>, A: Algorithm<T>> ops::Deref for MerkleTree<T, A> {
type Target = [T];
fn deref(&self) -> &[T] {
self.data.deref()
}
}
pub fn next_pow2(mut n: usize) -> usize {
n -= 1;
n |= n >> 1;
n |= n >> 2;
n |= n >> 4;
n |= n >> 8;
n |= n >> 16;
n |= n >> 32;
n + 1
}
pub fn log2_pow2(n: usize) -> usize {
n.trailing_zeros() as usize
}