From 2a8cd3c50c816d0cfb4c826087234aee3cf6674f Mon Sep 17 00:00:00 2001
From: Josh Kingsley <josh@joshkingsley.me>
Date: Tue, 18 Nov 2025 22:30:40 +0200
Subject: feat(crdt): delete cell entries in place

---
 crdt/src/lib.rs | 38 +++++++++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 7 deletions(-)

(limited to 'crdt/src/lib.rs')

diff --git a/crdt/src/lib.rs b/crdt/src/lib.rs
index a92b52d..cd86b97 100644
--- a/crdt/src/lib.rs
+++ b/crdt/src/lib.rs
@@ -1,6 +1,6 @@
 mod vector_clock;
 
-use std::{collections::BTreeSet, fmt::Display};
+use std::{collections::BTreeSet, fmt::Display, mem};
 
 use num_rational::Ratio;
 use uuid::Uuid;
@@ -165,6 +165,10 @@ impl Op {
                     (end_cell_idx, start_cell_idx)
                 };
 
+                for entry in row.value_mut().cells[i..(j + 1)].iter_mut() {
+                    entry.delete(self.id);
+                }
+
                 let span_duration: Ratio<u32> = row.value().cells[i..j + 1]
                     .iter()
                     .map(|cell| cell.value().duration)
@@ -210,12 +214,20 @@ pub struct Doc {
 }
 
 #[derive(Debug)]
-pub enum Entry<T> {
+pub enum Entry<T: Default> {
     Active { value: T },
     Deleted { value: T, deleted_by: Uuid },
 }
 
-impl<T> Entry<T> {
+impl<T: Default> Default for Entry<T> {
+    fn default() -> Self {
+        Self::Active {
+            value: T::default(),
+        }
+    }
+}
+
+impl<T: Default> Entry<T> {
     pub fn active(value: T) -> Self {
         Self::Active { value }
     }
@@ -240,27 +252,39 @@ impl<T> Entry<T> {
             Self::Deleted { value, .. } => value,
         }
     }
+
+    pub fn delete(&mut self, op_id: Uuid) {
+        if matches!(self, Self::Active { .. }) {
+            *self = match mem::take(self) {
+                Self::Active { value } => Self::Deleted {
+                    value,
+                    deleted_by: op_id,
+                },
+                _ => unreachable!(),
+            }
+        }
+    }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct Grid {
     id: DerivedId,
     rows: Vec<Entry<Row>>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct Row {
     id: DerivedId,
     cells: Vec<Entry<Cell>>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct Cell {
     id: DerivedId,
     duration: Ratio<u32>,
 }
 
-#[derive(PartialEq, Eq, Debug, Clone, Copy)]
+#[derive(PartialEq, Eq, Debug, Clone, Copy, Default)]
 pub struct DerivedId {
     // TODO These IDs can be interned on the Doc
     id: Uuid,
-- 
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