schala/schala-lang/src/util.rs

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use std::collections::HashMap;
use std::hash::Hash;
use std::cmp::Eq;
#[derive(Default, Debug)]
pub struct StateStack<'a, T: 'a, V: 'a> where T: Hash + Eq {
parent: Option<&'a StateStack<'a, T, V>>,
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values: HashMap<T, V>,
scope_name: Option<String>
}
impl<'a, T, V> StateStack<'a, T, V> where T: Hash + Eq {
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pub fn new(name: Option<String>) -> StateStack<'a, T, V> where T: Hash + Eq {
StateStack {
parent: None,
values: HashMap::new(),
scope_name: name
}
}
pub fn insert(&mut self, key: T, value: V) where T: Hash + Eq {
self.values.insert(key, value);
}
pub fn lookup(&self, key: &T) -> Option<&V> where T: Hash + Eq {
match (self.values.get(key), self.parent) {
(None, None) => None,
(None, Some(parent)) => parent.lookup(key),
(Some(value), _) => Some(value),
}
}
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pub fn new_frame(&'a self, name: Option<String>) -> StateStack<'a, T, V> where T: Hash + Eq {
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StateStack {
parent: Some(self),
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values: HashMap::default(),
scope_name: name,
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}
}
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pub fn get_name(&self) -> Option<&String> {
self.scope_name.as_ref()
}
}