172 lines
4.1 KiB
Rust
172 lines
4.1 KiB
Rust
//! Generete trie root
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use std::collections::BTreeMap;
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use std::cmp;
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use hash::*;
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use sha3::*;
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use rlp;
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use rlp::RlpStream;
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/// Hex-prefix Notation. First nibble has flags: oddness = 2^0 & termination = 2^1.
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///
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/// The "termination marker" and "leaf-node" specifier are completely equivalent.
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///
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/// Input values are in range `[0, 0xf]`.
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///
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/// ```markdown
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/// [0,0,1,2,3,4,5] 0x10012345 // 7 > 4
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/// [0,1,2,3,4,5] 0x00012345 // 6 > 4
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/// [1,2,3,4,5] 0x112345 // 5 > 3
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/// [0,0,1,2,3,4] 0x00001234 // 6 > 3
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/// [0,1,2,3,4] 0x101234 // 5 > 3
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/// [1,2,3,4] 0x001234 // 4 > 3
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/// [0,0,1,2,3,4,5,T] 0x30012345 // 7 > 4
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/// [0,0,1,2,3,4,T] 0x20001234 // 6 > 4
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/// [0,1,2,3,4,5,T] 0x20012345 // 6 > 4
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/// [1,2,3,4,5,T] 0x312345 // 5 > 3
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/// [1,2,3,4,T] 0x201234 // 4 > 3
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/// ```
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///
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/// ```rust
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/// extern crate ethcore_util as util;
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/// use util::triehash::*;
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///
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/// fn main() {
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/// let v = vec![0, 0, 1, 2, 3, 4, 5];
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/// let e = vec![0x10, 0x01, 0x23, 0x45];
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/// let h = hex_prefix_encode(&v, false);
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/// assert_eq!(h, e);
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///
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/// let v = vec![0, 1, 2, 3, 4, 5];
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/// let e = vec![0x00, 0x01, 0x23, 0x45];
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/// let h = hex_prefix_encode(&v, false);
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/// assert_eq!(h, e);
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///
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/// let v = vec![0, 1, 2, 3, 4, 5];
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/// let e = vec![0x20, 0x01, 0x23, 0x45];
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/// let h = hex_prefix_encode(&v, true);
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/// assert_eq!(h, e);
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///
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/// let v = vec![1, 2, 3, 4, 5];
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/// let e = vec![0x31, 0x23, 0x45];
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/// let h = hex_prefix_encode(&v, true);
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/// assert_eq!(h, e);
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///
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/// let v = vec![1, 2, 3, 4];
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/// let e = vec![0x00, 0x12, 0x34];
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/// let h = hex_prefix_encode(&v, false);
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/// assert_eq!(h, e);
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/// }
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/// ```
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///
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pub fn hex_prefix_encode(nibbles: &[u8], leaf: bool) -> Vec<u8> {
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let inlen = nibbles.len();
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let oddness_factor = inlen % 2;
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// next even number divided by two
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let reslen = (inlen + 2) >> 1;
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let mut res = vec![];
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res.reserve(reslen);
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let first_byte = {
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let mut bits = ((inlen as u8 & 1) + (2 * leaf as u8)) << 4;
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if oddness_factor == 1 {
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bits += nibbles[0];
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}
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bits
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};
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res.push(first_byte);
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let mut offset = oddness_factor;
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while offset < inlen {
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let byte = (nibbles[offset] << 4) + nibbles[offset + 1];
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res.push(byte);
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offset += 2;
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}
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res
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}
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/// Converts slice of bytes to nibbles.
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///
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/// ```rust
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/// extern crate ethcore_util as util;
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/// use util::triehash::*;
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///
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/// fn main () {
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/// let v = vec![0x31, 0x23, 0x45];
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/// let e = vec![3, 1, 2, 3, 4, 5];
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/// assert_eq!(as_nibbles(&v), e);
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/// }
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/// ```
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pub fn as_nibbles(bytes: &[u8]) -> Vec<u8> {
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let mut res = vec![];
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res.reserve(bytes.len() * 2);
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for i in 0..bytes.len() {
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res.push(bytes[i] >> 4);
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res.push((bytes[i] << 4) >> 4);
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}
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res
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}
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struct NibblePair {
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nibble: Vec<u8>,
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data: Vec<u8>
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}
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pub fn ordered_trie_root(data: Vec<Vec<u8>>) -> H256 {
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let vec: Vec<NibblePair> = data
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// first put elements into btree to sort them by nibbles
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// optimize it later
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.into_iter()
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.fold(BTreeMap::new(), | mut acc, vec | {
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let len = acc.len();
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acc.insert(as_nibbles(&rlp::encode(&len)), vec);
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acc
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})
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// then move them to a vector
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.into_iter()
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.map(|(k, v)| NibblePair { nibble: k, data: v } )
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.collect();
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let out = match vec.len() {
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0 => rlp::encode(&""),
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_ => {
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let mut stream = RlpStream::new();
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hash256rlp(&vec, 0, &mut stream);
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stream.out().unwrap()
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}
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};
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out.sha3()
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}
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fn shared_prefix_length<T>(v1: &[T], v2: &[T]) -> usize where T: Eq {
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let len = cmp::min(v1.len(), v2.len());
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(0..len).take_while(|&i| v1[i] == v2[i]).count()
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}
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fn hash256rlp(vec: &[NibblePair], pre_len: usize, stream: &mut RlpStream) {
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match vec.len() {
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0 => stream.append(&""),
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1 => stream.append_list(2).append(&hex_prefix_encode(&vec[0].nibble, true)).append(&vec[0].data),
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_ => {
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let shared_prefix = vec.iter()
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// skip first element
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.skip(1)
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// get minimum number of shared nibbles between first string and each successive
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.fold(usize::max_value(), | acc, pair | cmp::min(shared_prefix_length(&vec[0].nibble, &pair.nibble), acc) );
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//match shared_prefix > pre_len {
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//true => hex_prefix_encode(&vec[0].nibble
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//}
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panic!();
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}
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};
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}
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#[cfg(test)]
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mod tests {
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}
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