Crate quickscope
source · [−]Expand description
This crate contains two data structures for representing variable scopes:
ScopeMap and ScopeSet. They are analogous to HashMap and HashSet,
but the main difference is that they store their data in multiple “layers”,
or scopes.
When created, the ScopeMap and ScopeSet start with one base layer, which cannot be removed.
Additional layers can be added with push_layer(), and removed with pop_layer().
Removing a layer removes the entries defined on it.
ScopeMap is ideal for representing variable scopes and associated values,
while ScopeSet is more suitable for simply representing the presence of variables and their scopes.
Example
use quickscope::*;
let mut vars = ScopeMap::new();
// Define two variables in main scope
vars.define("a", 1);
vars.define("b", 2);
// Add a child scope
vars.push_layer();
// Override value of `a`
vars.define("a", 3);
assert_eq!(Some(&3), vars.get("a"));
assert_eq!(Some(&2), vars.get("b"));
// Remove child scope
vars.pop_layer();
// Value of `a` is no longer overridden
assert_eq!(Some(&1), vars.get("a"));