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Making Trie.iter non-recursive (#2733)

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This commit is contained in:
Tomasz Drwięga
2016-10-20 14:49:44 +02:00
committed by Gav Wood
parent 906dcd7bfe
commit 0017a43364
2 changed files with 73 additions and 41 deletions
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86
util/src/trie/triedb.rs
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@@ -304,14 +304,6 @@ impl<'a> TrieDBIterator<'a> {
Ok(())
}
/// Descend into a payload and get the next item.
fn descend_next(&mut self, d: &'a [u8]) -> Option<TrieItem<'a>> {
match self.descend(d) {
Ok(()) => self.next(),
Err(e) => Some(Err(e)),
}
}
/// The present key.
fn key(&self) -> Bytes {
// collapse the key_nibbles down to bytes.
@@ -323,38 +315,52 @@ impl<'a> Iterator for TrieDBIterator<'a> {
type Item = TrieItem<'a>;
fn next(&mut self) -> Option<Self::Item> {
let b = match self.trail.last_mut() {
Some(mut b) => { b.increment(); b.clone() },
None => return None,
};
match (b.status, b.node) {
(Status::Exiting, n) => {
match n {
Node::Leaf(n, _) | Node::Extension(n, _) => {
let l = self.key_nibbles.len();
self.key_nibbles.truncate(l - n.len());
},
Node::Branch(_, _) => { self.key_nibbles.pop(); },
_ => {}
}
self.trail.pop();
self.next()
},
(Status::At, Node::Leaf(_, v)) | (Status::At, Node::Branch(_, Some(v))) => Some(Ok((self.key(), v))),
(Status::At, Node::Extension(_, d)) => self.descend_next(d),
(Status::At, Node::Branch(_, _)) => self.next(),
(Status::AtChild(i), Node::Branch(children, _)) if children[i].len() > 0 => {
match i {
0 => self.key_nibbles.push(0),
i => *self.key_nibbles.last_mut().unwrap() = i as u8,
}
self.descend_next(children[i])
},
(Status::AtChild(i), Node::Branch(_, _)) => {
if i == 0 { self.key_nibbles.push(0); }
self.next()
},
_ => panic!() // Should never see Entering or AtChild without a Branch here.
loop {
let b = match self.trail.last_mut() {
Some(mut b) => { b.increment(); b.clone() },
None => return None,
};
match (b.status, b.node) {
(Status::Exiting, n) => {
match n {
Node::Leaf(n, _) | Node::Extension(n, _) => {
let l = self.key_nibbles.len();
self.key_nibbles.truncate(l - n.len());
},
Node::Branch(_, _) => { self.key_nibbles.pop(); },
_ => {}
}
self.trail.pop();
// continue
},
(Status::At, Node::Leaf(_, v)) | (Status::At, Node::Branch(_, Some(v))) => {
return Some(Ok((self.key(), v)));
},
(Status::At, Node::Extension(_, d)) => {
if let Err(e) = self.descend(d) {
return Some(Err(e));
}
// continue
},
(Status::At, Node::Branch(_, _)) => {},
(Status::AtChild(i), Node::Branch(children, _)) if children[i].len() > 0 => {
match i {
0 => self.key_nibbles.push(0),
i => *self.key_nibbles.last_mut().unwrap() = i as u8,
}
if let Err(e) = self.descend(children[i]) {
return Some(Err(e));
}
// continue
},
(Status::AtChild(i), Node::Branch(_, _)) => {
if i == 0 {
self.key_nibbles.push(0);
}
// continue
},
_ => panic!() // Should never see Entering or AtChild without a Branch here.
}
}
}
}