58 lines
1.2 KiB
Rust
58 lines
1.2 KiB
Rust
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//! Scoped hashmap.
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use fxhash::FxHashMap;
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use std::hash::Hash;
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pub struct ScopedMap<K: Hash + Eq, V> {
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map: FxHashMap<K, ScopedMapEntry<V>>,
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gen: u32,
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gen_by_level: Vec<u32>,
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}
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struct ScopedMapEntry<V> {
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gen: u32,
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level: u32,
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value: V,
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}
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impl<K: Hash + Eq, V> ScopedMap<K, V> {
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pub fn new() -> ScopedMap<K, V> {
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ScopedMap {
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map: FxHashMap::default(),
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gen: 0,
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gen_by_level: vec![0],
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}
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}
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pub fn push_level(&mut self) {
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self.gen += 1;
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self.gen_by_level.push(self.gen);
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}
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pub fn pop_level(&mut self) {
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self.gen_by_level.pop();
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}
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pub fn insert(&mut self, k: K, v: V) {
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self.map.insert(
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k,
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ScopedMapEntry {
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gen: self.gen,
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level: self.gen_by_level.len() as u32,
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value: v,
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},
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);
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}
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pub fn get(&self, k: &K) -> Option<&V> {
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self.map.get(k).and_then(|entry| {
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let level = entry.level as usize;
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if level < self.gen_by_level.len() && entry.gen == self.gen_by_level[level] {
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Some(&entry.value)
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} else {
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None
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}
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})
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}
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}
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