openethereum/util/src/trie/node.rs
Gav Wood 8404edb656 Fix whitespace (#4299)
* Fix whitespace.

* Update copyright years/owner.

* Push release only for tags.
2017-01-25 18:51:41 +01:00

167 lines
5.5 KiB
Rust

// Copyright 2015-2017 Parity Technologies (UK) Ltd.
// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
use elastic_array::ElasticArray36;
use nibbleslice::*;
use nibblevec::NibbleVec;
use bytes::*;
use rlp::*;
use hashdb::DBValue;
/// Partial node key type.
pub type NodeKey = ElasticArray36<u8>;
/// Type of node in the trie and essential information thereof.
#[derive(Eq, PartialEq, Debug, Clone)]
pub enum Node<'a> {
/// Null trie node; could be an empty root or an empty branch entry.
Empty,
/// Leaf node; has key slice and value. Value may not be empty.
Leaf(NibbleSlice<'a>, &'a [u8]),
/// Extension node; has key slice and node data. Data may not be null.
Extension(NibbleSlice<'a>, &'a [u8]),
/// Branch node; has array of 16 child nodes (each possibly null) and an optional immediate node data.
Branch([&'a [u8]; 16], Option<&'a [u8]>)
}
impl<'a> Node<'a> {
/// Decode the `node_rlp` and return the Node.
pub fn decoded(node_rlp: &'a [u8]) -> Self {
let r = Rlp::new(node_rlp);
match r.prototype() {
// either leaf or extension - decode first item with NibbleSlice::???
// and use is_leaf return to figure out which.
// if leaf, second item is a value (is_data())
// if extension, second item is a node (either SHA3 to be looked up and
// fed back into this function or inline RLP which can be fed back into this function).
Prototype::List(2) => match NibbleSlice::from_encoded(r.at(0).data()) {
(slice, true) => Node::Leaf(slice, r.at(1).data()),
(slice, false) => Node::Extension(slice, r.at(1).as_raw()),
},
// branch - first 16 are nodes, 17th is a value (or empty).
Prototype::List(17) => {
let mut nodes = [&[] as &[u8]; 16];
for i in 0..16 {
nodes[i] = r.at(i).as_raw();
}
Node::Branch(nodes, if r.at(16).is_empty() { None } else { Some(r.at(16).data()) })
},
// an empty branch index.
Prototype::Data(0) => Node::Empty,
// something went wrong.
_ => panic!("Rlp is not valid.")
}
}
/// Encode the node into RLP.
///
/// Will always return the direct node RLP even if it's 32 or more bytes. To get the
/// RLP which would be valid for using in another node, use `encoded_and_added()`.
pub fn encoded(&self) -> Bytes {
match *self {
Node::Leaf(ref slice, ref value) => {
let mut stream = RlpStream::new_list(2);
stream.append(&&*slice.encoded(true));
stream.append(value);
stream.out()
},
Node::Extension(ref slice, ref raw_rlp) => {
let mut stream = RlpStream::new_list(2);
stream.append(&&*slice.encoded(false));
stream.append_raw(raw_rlp, 1);
stream.out()
},
Node::Branch(ref nodes, ref value) => {
let mut stream = RlpStream::new_list(17);
for i in 0..16 {
stream.append_raw(nodes[i], 1);
}
match *value {
Some(ref n) => { stream.append(n); },
None => { stream.append_empty_data(); },
}
stream.out()
},
Node::Empty => {
let mut stream = RlpStream::new();
stream.append_empty_data();
stream.out()
}
}
}
}
/// An owning node type. Useful for trie iterators.
#[derive(Debug, PartialEq, Eq)]
pub enum OwnedNode {
/// Empty trie node.
Empty,
/// Leaf node: partial key and value.
Leaf(NibbleVec, DBValue),
/// Extension node: partial key and child node.
Extension(NibbleVec, DBValue),
/// Branch node: 16 children and an optional value.
Branch([NodeKey; 16], Option<DBValue>),
}
impl Clone for OwnedNode {
fn clone(&self) -> Self {
match *self {
OwnedNode::Empty => OwnedNode::Empty,
OwnedNode::Leaf(ref k, ref v) => OwnedNode::Leaf(k.clone(), v.clone()),
OwnedNode::Extension(ref k, ref c) => OwnedNode::Extension(k.clone(), c.clone()),
OwnedNode::Branch(ref c, ref v) => {
let mut children = [
NodeKey::new(), NodeKey::new(), NodeKey::new(), NodeKey::new(),
NodeKey::new(), NodeKey::new(), NodeKey::new(), NodeKey::new(),
NodeKey::new(), NodeKey::new(), NodeKey::new(), NodeKey::new(),
NodeKey::new(), NodeKey::new(), NodeKey::new(), NodeKey::new(),
];
for (owned, borrowed) in children.iter_mut().zip(c.iter()) {
*owned = borrowed.clone()
}
OwnedNode::Branch(children, v.as_ref().cloned())
}
}
}
}
impl<'a> From<Node<'a>> for OwnedNode {
fn from(node: Node<'a>) -> Self {
match node {
Node::Empty => OwnedNode::Empty,
Node::Leaf(k, v) => OwnedNode::Leaf(k.into(), DBValue::from_slice(v)),
Node::Extension(k, child) => OwnedNode::Extension(k.into(), DBValue::from_slice(child)),
Node::Branch(c, val) => {
let mut children = [
NodeKey::new(), NodeKey::new(), NodeKey::new(), NodeKey::new(),
NodeKey::new(), NodeKey::new(), NodeKey::new(), NodeKey::new(),
NodeKey::new(), NodeKey::new(), NodeKey::new(), NodeKey::new(),
NodeKey::new(), NodeKey::new(), NodeKey::new(), NodeKey::new(),
];
for (owned, borrowed) in children.iter_mut().zip(c.iter()) {
*owned = NodeKey::from_slice(borrowed)
}
OwnedNode::Branch(children, val.map(DBValue::from_slice))
}
}
}
}