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|
use std::fmt;
use std::collections::{BinaryHeap, HashMap};
use super::bits::BitSet;
pub struct Node {
occurences: usize,
content: Content,
}
impl Node {
fn join(left: Node, right: Node) -> Node {
Node {
occurences: left.occurences + right.occurences,
content: Content::Parent {
left: Box::new(left),
right: Box::new(right),
}
}
}
}
enum Content {
Leaf(u8),
Parent {
left: Box<Node>,
right: Box<Node>,
},
}
pub type Tree = Node;
impl Tree {
pub fn from_data(data: &[u8]) -> Tree {
let mut counter: HashMap<u8, usize> = HashMap::new();
for k in data {
let v = match counter.get(&k) {
Some(count) => count + 1,
None => 1,
};
counter.insert(*k, v);
}
let mut heap: BinaryHeap<Node> = counter
.iter()
.map(|(k, v)| Node { occurences: *v, content: Content::Leaf(*k) })
.collect();
while heap.len() >= 2 {
let first = heap.pop().unwrap();
let second = heap.pop().unwrap();
let n = Node::join(first, second);
heap.push(n);
}
heap.pop().unwrap()
}
pub fn to_hash_map(&self) -> HashMap<u8, BitSet> {
match &self.content {
Content::Leaf(b) => {
let mut hm = HashMap::with_capacity(1);
hm.insert(*b, BitSet::new());
hm
},
Content::Parent { left, right } => {
let mut left_hm = left.to_hash_map();
for (_, bits) in left_hm.iter_mut() {
bits.push_front_bit(0);
}
let mut right_hm = right.to_hash_map();
for (_, bits) in right_hm.iter_mut() {
bits.push_front_bit(1);
}
left_hm.extend(right_hm);
left_hm
},
}
}
fn fmt_spaces(f: &mut fmt::Formatter, level: usize) -> fmt::Result {
for _ in 0..level {
write!(f, " ")?;
}
Ok(())
}
fn fmt_with_level(&self, f: &mut fmt::Formatter, level: usize) -> fmt::Result {
match &self.content {
Content::Leaf(b) => {
write!(f, "{} {}\n", self.occurences, b)?;
},
Content::Parent { left, right } => {
write!(f, "NODE {}\n", self.occurences)?;
Tree::fmt_spaces(f, level)?;
write!(f, "left: ")?;
left.fmt_with_level(f, level + 1)?;
Tree::fmt_spaces(f, level)?;
write!(f, "right: ")?;
right.fmt_with_level(f, level + 1)?;
},
}
Ok(())
}
}
use std::cmp::Ordering;
impl Ord for Node {
fn cmp(&self, other: &Self) -> Ordering {
// self.occurences.cmp(&other.occurences)
other.occurences.cmp(&self.occurences) // dirty hack to fake min-heap
}
}
impl PartialOrd for Node {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Eq for Node {}
impl PartialEq for Node {
fn eq(&self, other: &Self) -> bool {
self.occurences == other.occurences
}
}
impl fmt::Debug for Tree {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.fmt_with_level(f, 0)
}
}
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