use std::cell::RefCell;
use std::collections::BTreeSet;
use std::rc::Rc;
#[derive(Debug, Clone, Default)]
pub struct StaticEnvironment {
variables: Rc<RefCell<BTreeSet<String>>>,
stack: Rc<RefCell<Vec<BTreeSet<String>>>>,
}
const FORWARD_ARGS: &str = "FORWARD_ARGS";
const ANONYMOUS_BLOCKARG: &str = "ANONYMOUS_BLOCKARG";
impl StaticEnvironment {
pub fn new() -> Self {
Self {
variables: Rc::new(RefCell::new(BTreeSet::new())),
stack: Rc::new(RefCell::new(vec![])),
}
}
pub(crate) fn is_empty(&self) -> bool {
self.stack.borrow().is_empty()
}
pub fn extend_static(&self) {
let variables = std::mem::take(&mut *self.variables.borrow_mut());
self.stack.borrow_mut().push(variables);
}
pub fn extend_dynamic(&self) {
self.stack
.borrow_mut()
.push(self.variables.borrow().clone());
}
pub fn unextend(&self) {
*self.variables.borrow_mut() = self
.stack
.borrow_mut()
.pop()
.expect("expected static_env to have at least one frame");
}
pub fn declare(&self, name: &str) {
self.variables.borrow_mut().insert(name.to_string());
}
pub fn is_declared(&self, name: &str) -> bool {
self.variables.borrow().get(name).is_some()
}
pub(crate) fn declare_forward_args(&self) {
self.declare(FORWARD_ARGS);
}
pub(crate) fn is_forward_args_declared(&self) -> bool {
self.is_declared(FORWARD_ARGS)
}
pub(crate) fn declare_anonymous_blockarg(&self) {
self.declare(ANONYMOUS_BLOCKARG)
}
pub(crate) fn is_anonymous_blockarg_declared(&self) -> bool {
self.is_declared(ANONYMOUS_BLOCKARG)
}
}
#[test]
fn test_declare() {
let env = StaticEnvironment::new();
assert!(!env.is_declared("foo"));
env.declare("foo");
assert!(env.is_declared("foo"));
}
#[test]
fn test_extend_static() {
let env = StaticEnvironment::new();
env.declare("foo");
env.extend_static();
env.declare("bar");
assert!(!env.is_declared("foo"));
assert!(env.is_declared("bar"));
}
#[test]
fn test_extend_dynamic() {
let env = StaticEnvironment::new();
env.declare("foo");
env.extend_dynamic();
env.declare("bar");
assert!(env.is_declared("foo"));
assert!(env.is_declared("bar"));
}
#[test]
fn test_unextend() {
let env = StaticEnvironment::new();
env.declare("foo");
env.extend_dynamic();
env.declare("bar");
env.unextend();
assert!(env.is_declared("foo"));
assert!(!env.is_declared("bar"));
}