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use elastic_array::ElasticArray36;
use nibble::NibbleSlice;
use nibble::nibble_ops;
use nibble::NibbleVec;
use super::DBValue;
#[cfg(not(feature = "std"))]
use alloc::vec::Vec;
pub type NodeKey = (usize, ElasticArray36<u8>);
#[derive(Eq, PartialEq, Clone)]
#[cfg_attr(feature = "std", derive(Debug))]
pub enum Node<'a> {
Empty,
Leaf(NibbleSlice<'a>, &'a [u8]),
Extension(NibbleSlice<'a>, &'a [u8]),
Branch([Option<&'a [u8]>; nibble_ops::NIBBLE_LENGTH], Option<&'a [u8]>),
NibbledBranch(NibbleSlice<'a>, [Option<&'a [u8]>; nibble_ops::NIBBLE_LENGTH], Option<&'a [u8]>),
}
#[cfg_attr(feature = "std", derive(Debug))]
#[derive(Eq, PartialEq, Clone)]
pub struct Branch {
data: Vec<u8>,
ubounds: [usize; 18],
has_value: bool,
}
impl Branch {
fn new(children: [Option<&[u8]>; 16], maybe_value: Option<&[u8]>) -> Self {
let mut data = Vec::with_capacity(children.iter()
.filter_map(|n| n.clone())
.map(|child| child.len())
.sum()
);
let mut ubounds = [0; 18];
for (maybe_child, ub) in children.iter().zip(ubounds.iter_mut().skip(1)) {
if let Some(child) = maybe_child {
data.extend_from_slice(child);
}
*ub = data.len();
}
if let Some(value) = maybe_value {
data.extend_from_slice(value);
ubounds[17] = data.len();
}
Branch { data, ubounds, has_value: maybe_value.is_some() }
}
pub fn get_value(&self) -> Option<&[u8]> {
if self.has_value {
Some(&self.data[self.ubounds[16]..self.ubounds[17]])
} else {
None
}
}
pub fn has_value(&self) -> bool {
self.has_value
}
pub fn index(&self, index: usize) -> Option<&[u8]> {
assert!(index < 16);
if self.ubounds[index] == self.ubounds[index + 1] {
None
} else {
Some(&self.data[self.ubounds[index]..self.ubounds[index + 1]])
}
}
}
#[cfg_attr(feature = "std", derive(Debug))]
#[derive(PartialEq, Eq)]
pub enum OwnedNode {
Empty,
Leaf(NibbleVec, DBValue),
Extension(NibbleVec, DBValue),
Branch(Branch),
NibbledBranch(NibbleVec, Branch),
}
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) =>
OwnedNode::Branch(Branch::new(c, val)),
Node::NibbledBranch(k, c, val) =>
OwnedNode::NibbledBranch(k.into(), Branch::new(c, val)),
}
}
}