forked from M-Labs/nac3
105 lines
2.6 KiB
Rust
105 lines
2.6 KiB
Rust
use std::cell::RefCell;
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use std::rc::Rc;
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#[derive(Copy, Clone, PartialEq, Eq, Debug)]
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pub struct UnificationKey(usize);
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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<V>,
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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 {
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parents: Vec::new(),
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ranks: Vec::new(),
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values: Vec::new(),
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}
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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(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(&mut self, a: UnificationKey) -> &V {
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let index = self.find(a);
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&self.values[index]
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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] = 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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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<RefCell<V>>>
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where
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V: Clone,
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{
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pub fn into_send(self) -> UnificationTable<V> {
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let values = self
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.values
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.iter()
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.map(|v| v.as_ref().borrow().clone())
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.collect();
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UnificationTable {
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parents: self.parents,
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ranks: self.ranks,
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values,
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}
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}
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pub fn from_send(table: UnificationTable<V>) -> UnificationTable<Rc<RefCell<V>>> {
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let values = table
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.values
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.into_iter()
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.map(|v| Rc::new(RefCell::new(v)))
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.collect();
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UnificationTable {
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parents: table.parents,
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ranks: table.ranks,
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values,
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}
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}
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}
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