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use crate::{
node_header::{size_and_prefix_iterator, NodeKind},
trie_constants,
};
use codec::{Compact, Encode};
use hash_db::Hasher;
use sp_std::vec::Vec;
use trie_root;
#[derive(Default, Clone)]
pub struct TrieStream {
buffer: Vec<u8>,
}
impl TrieStream {
pub fn as_raw(&self) -> &[u8] {
&self.buffer
}
}
fn branch_node_bit_mask(has_children: impl Iterator<Item = bool>) -> (u8, u8) {
let mut bitmap: u16 = 0;
let mut cursor: u16 = 1;
for v in has_children {
if v {
bitmap |= cursor
}
cursor <<= 1;
}
((bitmap % 256) as u8, (bitmap / 256) as u8)
}
fn fuse_nibbles_node(nibbles: &[u8], kind: NodeKind) -> impl Iterator<Item = u8> + '_ {
let size = sp_std::cmp::min(trie_constants::NIBBLE_SIZE_BOUND, nibbles.len());
let iter_start = match kind {
NodeKind::Leaf => size_and_prefix_iterator(size, trie_constants::LEAF_PREFIX_MASK, 2),
NodeKind::BranchNoValue =>
size_and_prefix_iterator(size, trie_constants::BRANCH_WITHOUT_MASK, 2),
NodeKind::BranchWithValue =>
size_and_prefix_iterator(size, trie_constants::BRANCH_WITH_MASK, 2),
NodeKind::HashedValueLeaf =>
size_and_prefix_iterator(size, trie_constants::ALT_HASHING_LEAF_PREFIX_MASK, 3),
NodeKind::HashedValueBranch =>
size_and_prefix_iterator(size, trie_constants::ALT_HASHING_BRANCH_WITH_MASK, 4),
};
iter_start
.chain(if nibbles.len() % 2 == 1 { Some(nibbles[0]) } else { None })
.chain(nibbles[nibbles.len() % 2..].chunks(2).map(|ch| ch[0] << 4 | ch[1]))
}
use trie_root::Value as TrieStreamValue;
impl trie_root::TrieStream for TrieStream {
fn new() -> Self {
Self { buffer: Vec::new() }
}
fn append_empty_data(&mut self) {
self.buffer.push(trie_constants::EMPTY_TRIE);
}
fn append_leaf(&mut self, key: &[u8], value: TrieStreamValue) {
let kind = match &value {
TrieStreamValue::Inline(..) => NodeKind::Leaf,
TrieStreamValue::Node(..) => NodeKind::HashedValueLeaf,
};
self.buffer.extend(fuse_nibbles_node(key, kind));
match &value {
TrieStreamValue::Inline(value) => {
Compact(value.len() as u32).encode_to(&mut self.buffer);
self.buffer.extend_from_slice(value);
},
TrieStreamValue::Node(hash) => {
self.buffer.extend_from_slice(hash.as_slice());
},
};
}
fn begin_branch(
&mut self,
maybe_partial: Option<&[u8]>,
maybe_value: Option<TrieStreamValue>,
has_children: impl Iterator<Item = bool>,
) {
if let Some(partial) = maybe_partial {
let kind = match &maybe_value {
None => NodeKind::BranchNoValue,
Some(TrieStreamValue::Inline(..)) => NodeKind::BranchWithValue,
Some(TrieStreamValue::Node(..)) => NodeKind::HashedValueBranch,
};
self.buffer.extend(fuse_nibbles_node(partial, kind));
let bm = branch_node_bit_mask(has_children);
self.buffer.extend([bm.0, bm.1].iter());
} else {
unreachable!("trie stream codec only for no extension trie");
}
match maybe_value {
None => (),
Some(TrieStreamValue::Inline(value)) => {
Compact(value.len() as u32).encode_to(&mut self.buffer);
self.buffer.extend_from_slice(value);
},
Some(TrieStreamValue::Node(hash)) => {
self.buffer.extend_from_slice(hash.as_slice());
},
}
}
fn append_extension(&mut self, _key: &[u8]) {
debug_assert!(false, "trie stream codec only for no extension trie");
}
fn append_substream<H: Hasher>(&mut self, other: Self) {
let data = other.out();
match data.len() {
0..=31 => data.encode_to(&mut self.buffer),
_ => H::hash(&data).as_ref().encode_to(&mut self.buffer),
}
}
fn out(self) -> Vec<u8> {
self.buffer
}
}