From 5b1117e582db16cc5aa50840a685875cbd5501f4 Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Tue, 14 Dec 2021 13:55:11 +0100
Subject: New model for buckets

---
 src/util/crdt/deletable.rs | 72 ++++++++++++++++++++++++++++++++++++++++++++++
 src/util/crdt/lww.rs       |  5 ++++
 src/util/crdt/lww_map.rs   | 12 +++++---
 src/util/crdt/mod.rs       |  2 ++
 4 files changed, 87 insertions(+), 4 deletions(-)
 create mode 100644 src/util/crdt/deletable.rs

(limited to 'src/util/crdt')

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),
+			}
+		}
+	}
+}
diff --git a/src/util/crdt/lww.rs b/src/util/crdt/lww.rs
index 43d13f27..bc686e05 100644
--- a/src/util/crdt/lww.rs
+++ b/src/util/crdt/lww.rs
@@ -82,6 +82,11 @@ where
 		&self.v
 	}
 
+	/// Take the value inside the CRDT (discards the timesamp)
+	pub fn take(self) -> T {
+		self.v
+	}
+
 	/// Get a mutable reference to the CRDT's value
 	///
 	/// This is usefull to mutate the inside value without changing the LWW timestamp.
diff --git a/src/util/crdt/lww_map.rs b/src/util/crdt/lww_map.rs
index 3e9aba79..21cb6e12 100644
--- a/src/util/crdt/lww_map.rs
+++ b/src/util/crdt/lww_map.rs
@@ -30,8 +30,8 @@ pub struct LwwMap<K, V> {
 
 impl<K, V> LwwMap<K, V>
 where
-	K: Ord,
-	V: Crdt,
+	K: Clone + Ord,
+	V: Clone + Crdt,
 {
 	/// Create a new empty map CRDT
 	pub fn new() -> Self {
@@ -73,6 +73,10 @@ where
 		};
 		Self { vals: new_vals }
 	}
+
+	pub fn update_in_place(&mut self, k: K, new_v: V) {
+		self.merge(&self.update_mutator(k, new_v));
+	}
 	/// Takes all of the values of the map and returns them. The current map is reset to the
 	/// empty map. This is very usefull to produce in-place a new map that contains only a delta
 	/// that modifies a certain value:
@@ -158,8 +162,8 @@ where
 
 impl<K, V> Default for LwwMap<K, V>
 where
-	K: Ord,
-	V: Crdt,
+	K: Clone + Ord,
+	V: Clone + Crdt,
 {
 	fn default() -> Self {
 		Self::new()
diff --git a/src/util/crdt/mod.rs b/src/util/crdt/mod.rs
index 9663a5a5..6ba575ed 100644
--- a/src/util/crdt/mod.rs
+++ b/src/util/crdt/mod.rs
@@ -12,12 +12,14 @@
 mod bool;
 #[allow(clippy::module_inception)]
 mod crdt;
+mod deletable;
 mod lww;
 mod lww_map;
 mod map;
 
 pub use self::bool::*;
 pub use crdt::*;
+pub use deletable::*;
 pub use lww::*;
 pub use lww_map::*;
 pub use map::*;
-- 
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