From 41309538fb4d43fd07ed3ff87e94d462099eba15 Mon Sep 17 00:00:00 2001
From: Alexis Sellier <alexis@radicle.xyz>
Date: Sun, 27 Nov 2022 12:58:10 +0100
Subject: [PATCH] crdt: Small improvements and function additions

Signed-off-by: Alexis Sellier <alexis@radicle.xyz>
---
 radicle-crdt/src/lwwmap.rs     | 16 ++++++++++++++++
 radicle-crdt/src/lwwreg.rs     |  3 ++-
 radicle-crdt/src/lwwset.rs     |  7 ++++++-
 radicle-crdt/src/redactable.rs | 27 +++++++++++++++++++++++++++
 4 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/radicle-crdt/src/lwwmap.rs b/radicle-crdt/src/lwwmap.rs
index 5aa61baa..84ed9d15 100644
--- a/radicle-crdt/src/lwwmap.rs
+++ b/radicle-crdt/src/lwwmap.rs
@@ -60,6 +60,10 @@ impl<K: Ord, V: Semilattice + PartialOrd + Eq, C: PartialOrd + Ord> LWWMap<K, V,
             .iter()
             .filter_map(|(k, v)| v.get().as_ref().map(|v| (k, v)))
     }
+
+    pub fn is_empty(&self) -> bool {
+        self.iter().next().is_none()
+    }
 }
 
 impl<K, V, C> Default for LWWMap<K, V, C> {
@@ -170,6 +174,18 @@ mod tests {
         assert!(!map.iter().any(|(c, _)| *c == 'a'));
     }
 
+    #[test]
+    fn test_is_empty() {
+        let mut map = LWWMap::default();
+        assert!(map.is_empty());
+
+        map.insert('a', Max::from("alice"), 1);
+        assert!(!map.is_empty());
+
+        map.remove('a', 2);
+        assert!(map.is_empty());
+    }
+
     #[test]
     fn test_remove_insert() {
         let mut map = LWWMap::default();
diff --git a/radicle-crdt/src/lwwreg.rs b/radicle-crdt/src/lwwreg.rs
index ffdc39e2..238a9260 100644
--- a/radicle-crdt/src/lwwreg.rs
+++ b/radicle-crdt/src/lwwreg.rs
@@ -1,5 +1,6 @@
 use num_traits::Bounded;
 
+use crate::clock;
 use crate::ord::Max;
 use crate::Semilattice;
 
@@ -7,7 +8,7 @@ use crate::Semilattice;
 ///
 /// In case of conflict, uses the [`Semilattice`] instance of `T` to merge.
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct LWWReg<T, C> {
+pub struct LWWReg<T, C = clock::Lamport> {
     clock: Max<C>,
     value: T,
 }
diff --git a/radicle-crdt/src/lwwset.rs b/radicle-crdt/src/lwwset.rs
index 68f9478a..c198b8d1 100644
--- a/radicle-crdt/src/lwwset.rs
+++ b/radicle-crdt/src/lwwset.rs
@@ -1,8 +1,9 @@
+use crate::clock;
 use crate::{lwwmap::LWWMap, Semilattice};
 
 /// Last-Write-Wins Set.
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct LWWSet<T, C> {
+pub struct LWWSet<T, C = clock::Lamport> {
     inner: LWWMap<T, (), C>,
 }
 
@@ -28,6 +29,10 @@ impl<T: Ord, C: Ord> LWWSet<T, C> {
     pub fn iter(&self) -> impl Iterator<Item = &T> {
         self.inner.iter().map(|(k, _)| k)
     }
+
+    pub fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
 }
 
 impl<T, C> Default for LWWSet<T, C> {
diff --git a/radicle-crdt/src/redactable.rs b/radicle-crdt/src/redactable.rs
index 55e0f0cf..326ad331 100644
--- a/radicle-crdt/src/redactable.rs
+++ b/radicle-crdt/src/redactable.rs
@@ -18,6 +18,15 @@ pub enum Redactable<T> {
     Redacted,
 }
 
+impl<T> Redactable<T> {
+    pub fn get(&self) -> Option<&T> {
+        match self {
+            Self::Present(val) => Some(val),
+            Self::Redacted => None,
+        }
+    }
+}
+
 impl<T> From<Option<T>> for Redactable<T> {
     fn from(option: Option<T>) -> Self {
         match option {
@@ -27,6 +36,24 @@ impl<T> From<Option<T>> for Redactable<T> {
     }
 }
 
+impl<T> From<Redactable<T>> for Option<T> {
+    fn from(redactable: Redactable<T>) -> Self {
+        match redactable {
+            Redactable::Present(v) => Some(v),
+            Redactable::Redacted => None,
+        }
+    }
+}
+
+impl<'a, T> From<&'a Redactable<T>> for Option<&'a T> {
+    fn from(redactable: &'a Redactable<T>) -> Self {
+        match redactable {
+            Redactable::Present(v) => Some(v),
+            Redactable::Redacted => None,
+        }
+    }
+}
+
 impl<T: PartialEq> Semilattice for Redactable<T> {
     fn merge(&mut self, other: Self) {
         match (&self, other) {