feat: Implement weak-table traits

Cargo.toml

@@ -24,6 +24,7 @@ features = ["unstable_docrs"]
 [features]
 with_ahash = ["ahash"]
 unstable_docrs = ["with_ahash"]
+weak-table = ["dep:weak-table"]
 
 [dependencies]
 lazy_static = "1.*"
@@ -32,6 +33,10 @@ lazy_static = "1.*"
 version = "^0.8.3"
 optional = true
 
+[dependencies.weak-table]
+version = "^0.3.0"
+optional = true
+
 [dev-dependencies]
 crossbeam-utils = "^0.8"
 trybuild = "^1.0"

src/lib.rs

@@ -451,6 +451,43 @@ impl<T> Ord for WHConsed<T> {
     }
 }
 
+#[cfg(feature = "weak-table")]
+use weak_table::traits::{WeakElement, WeakKey};
+
+#[cfg(feature = "weak-table")]
+impl<T> WeakElement for WHConsed<T> {
+   type Strong = HConsed<T>;
+	fn new(x: &Self::Strong) -> Self
+	{
+      x.to_weak()
+	}
+	fn view(&self) -> Option<Self::Strong>
+	{
+      self.to_hconsed()
+	}
+	fn is_expired(&self) -> bool
+	{
+		self.elm.is_expired()
+	}
+	fn clone(x: &Self::Strong) -> Self::Strong
+	where
+		Self: Sized,
+	{
+		x.clone()
+	}
+}
+#[cfg(feature = "weak-table")]
+impl<T: std::hash::Hash + Eq> WeakKey for WHConsed<T> {
+	type Key = T;
+	fn with_key<F, R>(view: &Self::Strong, f: F) -> R
+	where
+		F: FnOnce(&Self::Key) -> R,
+	{
+		f(view)
+	}
+}
+
+
 /// The consign storing the actual hash consed elements as `HConsed`s.
 pub struct HConsign<T: Hash + Eq + Clone, S = RandomState> {
     /// The actual hash consing table.