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use super::{CError, DBValue, Query, Result, TrieError, TrieHash, TrieLayout};
use crate::{
nibble::NibbleSlice,
node::{decode_hash, Node, NodeHandle, Value},
node_codec::NodeCodec,
rstd::boxed::Box,
};
use hash_db::{HashDBRef, Prefix};
pub struct Lookup<'a, L: TrieLayout, Q: Query<L::Hash>> {
pub db: &'a dyn HashDBRef<L::Hash, DBValue>,
pub query: Q,
pub hash: TrieHash<L>,
}
impl<'a, L, Q> Lookup<'a, L, Q>
where
L: TrieLayout,
Q: Query<L::Hash>,
{
fn decode(
mut self,
v: Value,
prefix: Prefix,
depth: u32,
) -> Result<Q::Item, TrieHash<L>, CError<L>> {
match v {
Value::Inline(value) => Ok(self.query.decode(value)),
Value::Node(_, Some(value)) => Ok(self.query.decode(value.as_slice())),
Value::Node(hash, None) => {
let mut res = TrieHash::<L>::default();
res.as_mut().copy_from_slice(hash);
if let Some(value) = self.db.get(&res, prefix) {
self.query.record(&res, &value, depth);
Ok(self.query.decode(value.as_slice()))
} else {
Err(Box::new(TrieError::IncompleteDatabase(res)))
}
},
}
}
pub fn look_up(mut self, key: NibbleSlice) -> Result<Option<Q::Item>, TrieHash<L>, CError<L>> {
let mut partial = key;
let mut key_nibbles = 0;
let mut full_key = key.clone();
full_key.advance(key.len());
let full_key = full_key.left();
for depth in 0.. {
let hash = self.hash;
let node_data = match self.db.get(&hash, key.mid(key_nibbles).left()) {
Some(value) => value,
None =>
return Err(Box::new(match depth {
0 => TrieError::InvalidStateRoot(hash),
_ => TrieError::IncompleteDatabase(hash),
})),
};
self.query.record(&hash, &node_data, depth);
let mut node_data = &node_data[..];
loop {
let decoded = match L::Codec::decode(node_data) {
Ok(node) => node,
Err(e) => return Err(Box::new(TrieError::DecoderError(hash, e))),
};
let next_node = match decoded {
Node::Leaf(slice, value) =>
return Ok(match slice == partial {
true => Some(self.decode(value, full_key, depth)?),
false => None,
}),
Node::Extension(slice, item) =>
if partial.starts_with(&slice) {
partial = partial.mid(slice.len());
key_nibbles += slice.len();
item
} else {
return Ok(None)
},
Node::Branch(children, value) => match partial.is_empty() {
true =>
if let Some(value) = value {
return Ok(Some(self.decode(value, full_key, depth)?))
} else {
return Ok(None)
},
false => match children[partial.at(0) as usize] {
Some(x) => {
partial = partial.mid(1);
key_nibbles += 1;
x
},
None => return Ok(None),
},
},
Node::NibbledBranch(slice, children, value) => {
if !partial.starts_with(&slice) {
return Ok(None)
}
match partial.len() == slice.len() {
true =>
if let Some(value) = value {
return Ok(Some(self.decode(value, full_key, depth)?))
} else {
return Ok(None)
},
false => match children[partial.at(slice.len()) as usize] {
Some(x) => {
partial = partial.mid(slice.len() + 1);
key_nibbles += slice.len() + 1;
x
},
None => return Ok(None),
},
}
},
Node::Empty => return Ok(None),
};
match next_node {
NodeHandle::Hash(data) => {
self.hash = decode_hash::<L::Hash>(data)
.ok_or_else(|| Box::new(TrieError::InvalidHash(hash, data.to_vec())))?;
break
},
NodeHandle::Inline(data) => {
node_data = data;
},
}
}
}
Ok(None)
}
}