forked from M-Labs/nac3
111 lines
3.1 KiB
Rust
111 lines
3.1 KiB
Rust
use std::rc::Rc;
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use itertools::izip;
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#[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
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pub struct UnificationKey(usize);
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#[derive(Clone)]
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pub struct UnificationTable<V> {
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parents: Vec<usize>,
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ranks: Vec<u32>,
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values: Vec<Option<V>>,
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}
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impl<V> Default for UnificationTable<V> {
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fn default() -> Self {
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Self::new()
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}
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}
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impl<V> UnificationTable<V> {
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pub fn new() -> UnificationTable<V> {
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UnificationTable { parents: Vec::new(), ranks: Vec::new(), values: Vec::new() }
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}
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pub fn new_key(&mut self, v: V) -> UnificationKey {
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let index = self.parents.len();
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self.parents.push(index);
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self.ranks.push(0);
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self.values.push(Some(v));
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UnificationKey(index)
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}
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pub fn unify(&mut self, a: UnificationKey, b: UnificationKey) {
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let mut a = self.find(a);
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let mut b = self.find(b);
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if a == b {
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return;
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}
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if self.ranks[a] < self.ranks[b] {
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std::mem::swap(&mut a, &mut b);
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}
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self.parents[b] = a;
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if self.ranks[a] == self.ranks[b] {
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self.ranks[a] += 1;
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}
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}
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pub fn probe_value_immutable(&self, key: UnificationKey) -> &V {
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let mut root = key.0;
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let mut parent = self.parents[root];
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while root != parent {
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root = parent;
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// parent = root.parent
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parent = self.parents[parent];
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}
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self.values[parent].as_ref().unwrap()
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}
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pub fn probe_value(&mut self, a: UnificationKey) -> &V {
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let index = self.find(a);
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self.values[index].as_ref().unwrap()
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}
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pub fn set_value(&mut self, a: UnificationKey, v: V) {
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let index = self.find(a);
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self.values[index] = Some(v);
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}
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pub fn unioned(&mut self, a: UnificationKey, b: UnificationKey) -> bool {
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self.find(a) == self.find(b)
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}
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pub fn get_representative(&mut self, key: UnificationKey) -> UnificationKey {
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UnificationKey(self.find(key))
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}
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fn find(&mut self, key: UnificationKey) -> usize {
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let mut root = key.0;
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let mut parent = self.parents[root];
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while root != parent {
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// a = parent.parent
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let a = self.parents[parent];
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// root.parent = parent.parent
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self.parents[root] = a;
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root = parent;
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// parent = root.parent
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parent = a;
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}
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parent
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}
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}
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impl<V> UnificationTable<Rc<V>>
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where
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V: Clone,
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{
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pub fn get_send(&self) -> UnificationTable<V> {
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let values = izip!(self.values.iter(), self.parents.iter())
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.enumerate()
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.map(|(i, (v, p))| if *p == i { v.as_ref().map(|v| v.as_ref().clone()) } else { None })
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.collect();
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UnificationTable { parents: self.parents.clone(), ranks: self.ranks.clone(), values }
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}
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pub fn from_send(table: &UnificationTable<V>) -> UnificationTable<Rc<V>> {
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let values = table.values.iter().cloned().map(|v| v.map(Rc::new)).collect();
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UnificationTable { parents: table.parents.clone(), ranks: table.ranks.clone(), values }
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}
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}
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