82ecd61f5c
Change-Id: I6c6847fac56f0a9a1a2209792e00a3aec5e672b9 Reviewed-on: https://cl.tvl.fyi/c/depot/+/10809 Autosubmit: aspen <root@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI Reviewed-by: lukegb <lukegb@tvl.fyi>
59 lines
1.1 KiB
Rust
59 lines
1.1 KiB
Rust
use std::borrow::Borrow;
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use std::collections::HashMap;
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use std::hash::Hash;
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use std::mem;
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/// A lexical environment
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#[derive(Debug, PartialEq, Eq)]
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pub struct Env<K: Eq + Hash, V>(Vec<HashMap<K, V>>);
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impl<K, V> Default for Env<K, V>
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where
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K: Eq + Hash,
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{
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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<K, V> Env<K, V>
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where
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K: Eq + Hash,
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{
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pub fn new() -> Self {
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Self(vec![Default::default()])
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}
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pub fn push(&mut self) {
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self.0.push(Default::default());
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}
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pub fn pop(&mut self) {
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self.0.pop();
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}
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pub fn save(&mut self) -> Self {
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mem::take(self)
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}
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pub fn restore(&mut self, saved: Self) {
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*self = saved;
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}
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pub fn set(&mut self, k: K, v: V) {
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self.0.last_mut().unwrap().insert(k, v);
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}
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pub fn resolve<'a, Q>(&'a self, k: &Q) -> Option<&'a V>
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where
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K: Borrow<Q>,
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Q: Hash + Eq + ?Sized,
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{
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for ctx in self.0.iter().rev() {
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if let Some(res) = ctx.get(k) {
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return Some(res);
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}
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}
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None
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}
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}
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