1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127

pub mod hash;

use hash::{hash, zero_hash};

use bonsai::{
    children, expand, first_leaf, last_leaf, log2, relative_depth, subtree_index_to_general,
};
use std::cmp::{min, Reverse};
use std::collections::{BTreeMap, BinaryHeap, HashSet};

pub type K = u128;
pub type V = [u8; 32];

#[derive(Debug, Default, PartialEq)]
pub struct Tree {
    map: BTreeMap<K, V>,
}

impl Tree {
    pub fn new() -> Self {
        Self {
            map: BTreeMap::new(),
        }
    }

    pub fn from_map(map: BTreeMap<K, V>) -> Self {
        Self { map }
    }

    pub fn get(&self, key: &K) -> Option<&V> {
        self.map.get(key)
    }

    pub fn insert(&mut self, key: K, val: V) -> Option<V> {
        self.map.insert(key, val)
    }

    pub fn keys(&self) -> HashSet<K> {
        self.map.keys().cloned().collect()
    }

    fn leaf_keys(&self, root: K, depth: u32) -> HashSet<K> {
        (first_leaf(root, depth as u128)..=last_leaf(root, depth as u128)).collect()
    }

    pub fn fill_subtree(&mut self, root: K, depth: u32, default: &V) {
        let mut keys: BinaryHeap<Reverse<u128>> = self
            .keys()
            .intersection(&self.leaf_keys(root, depth))
            .cloned()
            // mapping to reverse turns this into a min-heap
            .map(Reverse)
            .collect();

        while let Some(Reverse(key)) = keys.pop() {
            if key <= root {
                break;
            }

            let (left, right, parent) = expand(key);

            if !self.map.contains_key(&parent) {
                let mut get_or_insert = |n: K| -> V {
                    *self.map.entry(n).or_insert(zero_hash(
                        default,
                        relative_depth(n, first_leaf(root, depth as u128)),
                    ))
                };

                let left = get_or_insert(left);
                let right = get_or_insert(right);

                self.map.insert(parent, hash(&left, &right));
                keys.push(Reverse(parent));
            }
        }
    }

    pub fn trim(mut self) -> Self {
        for key in self.keys() {
            let (left, right) = children(key);

            if self.map.contains_key(&left) || self.map.contains_key(&right) {
                self.map.remove(&key);
            }
        }

        self
    }

    pub fn set_root(&mut self, root: K) {
        let keys = self.keys();
        for k in keys {
            let value = self.map.remove(&k).unwrap();
            self.map.insert(subtree_index_to_general(root, k), value);
        }
    }

    pub fn insert_bytes(&mut self, rooted_at: K, bytes: Vec<u8>) {
        let len = bytes.len() as K;
        let padded_len = len
            .checked_next_power_of_two()
            .expect("compiled code to fit in tree");
        let depth = log2(padded_len / 32);
        let first: K = first_leaf(rooted_at, depth);

        for i in (0..len).step_by(32) {
            let begin = i as usize;
            let end = min(i + 32, len) as usize;

            let chunk_len = if i + 32 < len {
                32
            } else {
                if end % 32 != 0 {
                    end % 32
                } else {
                    32
                }
            };

            let mut buf = [0u8; 32];
            buf[0..chunk_len].copy_from_slice(&bytes[begin..end]);

            self.map.insert(first + (i / 32), buf);
        }
    }
}