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#![no_std] pub mod hash; extern crate alloc; use crate::hash::hash; use alloc::collections::{BTreeMap, BTreeSet, BinaryHeap}; use arrayref::array_ref; use bonsai::expand; use core::mem::size_of; use core::slice::{from_raw_parts, from_raw_parts_mut}; #[cfg(any(test, feature = "generate"))] use alloc::vec::Vec; type K = u128; type V = [u8; 32]; type Map = BTreeMap<K, V>; #[derive(Clone, Debug, PartialEq)] pub struct Oof { pub map: Map, } #[derive(Debug, PartialEq)] pub enum Error { EntryNotFound(K), } impl Oof { pub fn new(keys: &[K], values: &[V]) -> Self { let mut map = Map::new(); for i in 0..keys.len() { map.insert(keys[i], values[i]); } Self { map } } pub unsafe fn from_raw(data: *mut u8) -> Self { let count = u32::from_le_bytes(*array_ref![from_raw_parts(data, 4), 0, 4]) as usize; let keys = data.offset(4) as *mut K; let values = data.offset(4 + (count * size_of::<K>()) as isize) as *mut V; Self::new( from_raw_parts_mut(keys, count), from_raw_parts_mut(values, count), ) } pub fn from_map(map: Map) -> Self { Self { map } } #[cfg(any(test, feature = "generate"))] pub fn to_map(self) -> Map { self.map } #[cfg(any(test, feature = "generate"))] pub fn to_bytes(&self) -> Vec<u8> { let keys: Vec<u8> = self .map .keys() .flat_map(|k| k.to_le_bytes().to_vec()) .collect(); let values: Vec<u8> = self.map.values().flatten().cloned().collect(); let mut ret = (self.map.keys().len() as u32).to_le_bytes().to_vec(); ret.extend(keys); ret.extend(values); ret } pub fn get(&self, key: &K) -> Option<&V> { self.map.get(key) } pub fn set(&mut self, key: K, value: V) -> Option<V> { let (_, _, parent) = expand(key); self.map.remove(&parent); self.map.insert(key, value) } pub fn root(&mut self) -> Result<&V, Error> { self.refresh()?; Ok(self.get(&1).ok_or(Error::EntryNotFound(1))?) } pub fn keys(&self) -> BTreeSet<K> { self.map.keys().cloned().collect() } fn refresh(&mut self) -> Result<(), Error> { let mut keys: BinaryHeap<u128> = self.keys().into_iter().collect(); while let Some(key) = keys.pop() { if key <= 1 { break; } let (left, right, parent) = expand(key); match (self.get(&left), self.get(&right), self.get(&parent)) { (Some(l), Some(r), None) => { let h = hash(l, r); self.set(parent, h); keys.push(parent); } (Some(_), Some(_), Some(_)) => (), (None, _, _) => return Err(Error::EntryNotFound(left)), (_, None, _) => return Err(Error::EntryNotFound(right)), }; } Ok(()) } } #[cfg(test)] mod tests { use super::*; use core::mem::transmute; fn build_value(n: u8) -> [u8; 32] { let mut tmp = [0u8; 32]; tmp[0] = n; tmp } #[test] fn root() { let mut keys = [2, 6, 7]; let mut values = [build_value(2), build_value(6), build_value(7)]; let mut oof = Oof::new(&mut keys, &mut values); let three = hash(&values[1], &values[2]); let one = hash(&values[0], &three); assert_eq!(oof.root(), Ok(&one)); } #[test] fn from_blob() { let count: u32 = 3; let keys: [K; 3] = [1, 2, 3]; let values: [V; 3] = [build_value(1), build_value(2), build_value(3)]; let keys: [u8; 48] = unsafe { transmute(keys) }; let values: [u8; 96] = unsafe { transmute(values) }; let mut blob = [0u8; (4 + 48 + 96)]; blob[0..4].copy_from_slice(&count.to_le_bytes()); blob[4..52].copy_from_slice(&keys[..]); blob[52..148].copy_from_slice(&values[..]); let oof = unsafe { Oof::from_raw(blob[..].as_ptr() as *mut u8) }; assert_eq!(oof.get(&1), Some(&build_value(1))); assert_eq!(oof.get(&2), Some(&build_value(2))); assert_eq!(oof.get(&3), Some(&build_value(3))); assert_eq!(oof.get(&4), None); } }