StateVector - add partial comparison

y-crdt · Aug 29, 2024 · 47b083f · 47b083f
1 parent 831c806
commit 47b083f
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Showing 2 changed files with 32 additions and 1 deletion.
diff --git a/yrs/src/lib.rs b/yrs/src/lib.rs
@@ -631,7 +631,9 @@ pub use crate::out::Out;
 pub use crate::state_vector::Snapshot;
 pub use crate::state_vector::StateVector;
 pub use crate::store::Store;
-pub use crate::transact::{AsyncTransact, Transact, TransactionAcqError};
+pub use crate::transact::{
+    AcquireTransaction, AcquireTransactionMut, AsyncTransact, Transact, TransactionAcqError,
+};
 pub use crate::transaction::Origin;
 pub use crate::transaction::ReadTxn;
 pub use crate::transaction::RootRefs;

diff --git a/yrs/src/state_vector.rs b/yrs/src/state_vector.rs
@@ -4,6 +4,7 @@ use crate::updates::decoder::{Decode, Decoder};
 use crate::updates::encoder::{Encode, Encoder};
 use crate::utils::client_hasher::ClientHasher;
 use crate::{DeleteSet, ID};
+use std::cmp::Ordering;
 use std::collections::hash_map::Entry;
 use std::collections::HashMap;
 use std::hash::BuildHasherDefault;
@@ -138,6 +139,34 @@ impl Encode for StateVector {
     }
 }
 
+impl PartialOrd for StateVector {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        let mut result = Some(Ordering::Equal);
+
+        for (client, clock) in self.iter() {
+            let other_clock = other.get(client);
+            match clock.cmp(&other_clock) {
+                Ordering::Less if result == Some(Ordering::Greater) => return None,
+                Ordering::Greater if result == Some(Ordering::Less) => return None,
+                Ordering::Equal => { /* unchanged */ }
+                other => result = Some(other),
+            }
+        }
+
+        for (other_client, other_clock) in other.iter() {
+            let clock = self.get(other_client);
+            match clock.cmp(&other_clock) {
+                Ordering::Less if result == Some(Ordering::Greater) => return None,
+                Ordering::Greater if result == Some(Ordering::Less) => return None,
+                Ordering::Equal => { /* unchanged */ }
+                other => result = Some(other),
+            }
+        }
+
+        result
+    }
+}
+
 /// Snapshot describes a state of a document store at a given point in (logical) time. In practice
 /// it's a combination of [StateVector] (a summary of all observed insert/update operations)
 /// and a [DeleteSet] (a summary of all observed deletions).