1 files changed, 72 insertions, 0 deletions
diff --git a/src/util/crdt/deletable.rs b/src/util/crdt/deletable.rs
new file mode 100644
index 00000000..c76f5cbb
--- /dev/null
+++ b/src/util/crdt/deletable.rs
@@ -0,0 +1,72 @@
+use serde::{Deserialize, Serialize};
+
+use crate::crdt::crdt::*;
+
+/// Deletable object (once deleted, cannot go back)
+#[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq)]
+pub enum Deletable<T> {
+	Present(T),
+	Deleted,
+}
+
+impl<T: Crdt> Deletable<T> {
+	/// Create a new deletable object that isn't deleted
+	pub fn present(v: T) -> Self {
+		Self::Present(v)
+	}
+	/// Create a new deletable object that is deleted
+	pub fn delete() -> Self {
+		Self::Deleted
+	}
+	/// As option
+	pub fn as_option(&self) -> Option<&T> {
+		match self {
+			Self::Present(v) => Some(v),
+			Self::Deleted => None,
+		}
+	}
+	/// As option, mutable
+	pub fn as_option_mut(&mut self) -> Option<&mut T> {
+		match self {
+			Self::Present(v) => Some(v),
+			Self::Deleted => None,
+		}
+	}
+	/// Into option
+	pub fn into_option(self) -> Option<T> {
+		match self {
+			Self::Present(v) => Some(v),
+			Self::Deleted => None,
+		}
+	}
+	/// Is object deleted?
+	pub fn is_deleted(&self) -> bool {
+		matches!(self, Self::Deleted)
+	}
+}
+
+impl<T> From<Option<T>> for Deletable<T> {
+	fn from(v: Option<T>) -> Self {
+		v.map(Self::Present).unwrap_or(Self::Deleted)
+	}
+}
+
+impl<T> From<Deletable<T>> for Option<T> {
+	fn from(v: Deletable<T>) -> Option<T> {
+		match v {
+			Deletable::Present(v) => Some(v),
+			Deletable::Deleted => None,
+		}
+	}
+}
+
+impl<T: Crdt> Crdt for Deletable<T> {
+	fn merge(&mut self, other: &Self) {
+		if let Deletable::Present(v) = self {
+			match other {
+				Deletable::Deleted => *self = Deletable::Deleted,
+				Deletable::Present(v2) => v.merge(v2),
+			}
+		}
+	}
+}