zypo_lib/parser/
scope.rs

1//! Contains the primary scoping structure and various trait implementations.
2use std::collections::HashMap;
3use std::hash::Hash;
4
5/// Structure for storing an AST node as a hashmap node inside of a vector.
6///
7/// To use this structure, a node type has to implament [Hash] and [Eq] (similar
8/// to [PartialEq]).
9pub struct Scope<K: Hash + Eq, V>(Vec<HashMap<K, V>>);
10
11impl<K: Hash + Eq, V> Scope<K, V> {
12    /// Creates a new, empty scope.
13    #[inline]
14    pub fn new() -> Self {
15        Self(vec![HashMap::new()])
16    }
17
18    /// Creates a new scope at top of stack, acting as a new scope.
19    #[inline]
20    pub fn enter_scope(&mut self) {
21        self.0.push(HashMap::<K, V>::new());
22    }
23
24    /// Leaves the scope by popping the top value of the [HashMap] vector stack.
25    #[inline]
26    pub fn leave_scope(&mut self) {
27        self.0.pop();
28    }
29
30    /// Scans bottom-up from the scope stack to find the specified `item`
31    /// argument. This method recurses down the branches of the stack until it
32    /// finds the item (linear search).
33    #[inline]
34    pub fn get(&self, item: &K) -> Option<&V> {
35        for stack_item in self.0.iter().rev() {
36            let cur_item = stack_item.get(item);
37            if cur_item.is_some() {
38                return cur_item;
39            }
40        }
41
42        None
43    }
44
45    /// Inserts a new item into the stack.
46    ///
47    /// NOTE: This will panic if a fatal error occurs if inserting into a broken
48    /// stack.
49    #[inline]
50    pub fn insert(&mut self, key: K, value: V) -> Option<V> {
51        self.0.last_mut().unwrap().insert(key, value)
52    }
53
54    /// Gets the depth of the entire [Scope] data structure.
55    pub fn depth(&self) -> usize {
56        self.0.len()
57    }
58}
zypo_lib/parser/scope.rs

zypo_lib/parser/
scope.rs
