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Merge rust-bitcoin/rust-bitcoin#914: Taproot Huffman tree builder u64->u32 fixes 

8dabe3ed64 Taproot Huffman tree builder u64->u32 fixes (Dr Maxim Orlovsky)

Pull request description:

  Follow-up fixes for #909

ACKs for top commit:
  sanket1729:
    ACK 8dabe3ed64
  apoelstra:
    ACK 8dabe3ed64

Tree-SHA512: 0e05b2183c7746ed57b0f585abf769d10b638840e9b8b0de07e718f451f349c15c06e223930fd51b192f1328734fabf242f1fa701518ebc57ceed4b4d85c8dbe
This commit is contained in:
Andrew Poelstra 2022-03-28 17:04:12 +00:00
parent 7f53c2cdc1 8dabe3ed64
commit 1c923c1da6
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1 changed files with 5 additions and 5 deletions
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10
src/util/taproot.rs
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@ -367,8 +367,8 @@ impl TaprootBuilder {
/// weights of satisfaction for that script. The weights represent the probability of
/// each branch being taken. If probabilities/weights for each condition are known,
/// constructing the tree as a Huffman tree is the optimal way to minimize average
/// case satisfaction cost. This function takes input an iterator of tuple(u64, &Script)
/// where usize represents the satisfaction weights of the branch.
/// case satisfaction cost. This function takes an iterator of (`u32`, &[`Script`]) tuples
/// as an input, where `u32` represents the satisfaction weights of the script branch.
/// For example, [(3, S1), (2, S2), (5, S3)] would construct a TapTree that has optimal
/// satisfaction weight when probability for S1 is 30%, S2 is 20% and S3 is 50%.
///
@ -387,9 +387,9 @@ impl TaprootBuilder {
where
I: IntoIterator<Item=(u32, Script)>,
{
let mut node_weights = BinaryHeap::<(Reverse<u64>, NodeInfo)>::new();
let mut node_weights = BinaryHeap::<(Reverse<u32>, NodeInfo)>::new();
for (p, leaf) in script_weights {
node_weights.push((Reverse(p as u64), NodeInfo::new_leaf_with_ver(leaf, LeafVersion::TapScript)));
node_weights.push((Reverse(p), NodeInfo::new_leaf_with_ver(leaf, LeafVersion::TapScript)));
}
if node_weights.is_empty() {
return Err(TaprootBuilderError::IncompleteTree);
@ -407,7 +407,7 @@ impl TaprootBuilder {
}
// Every iteration of the loop reduces the node_weights.len() by exactly 1
// Therefore, the loop will eventually terminate with exactly 1 element
debug_assert!(node_weights.len() == 1);
debug_assert_eq!(node_weights.len(), 1);
let node = node_weights.pop().expect("huffman tree algorithm is broken").1;
Ok(TaprootBuilder{branch: vec![Some(node)]})
}