Add incremental index

instant-distance/src/lib.rs

@@ -170,6 +170,12 @@ where
     pub fn get(&self, i: usize, search: &Search) -> Option<MapItem<'_, P, V>> {
         Some(MapItem::from(self.hnsw.get(i, search)?, self))
     }
+
+    pub fn insert(&mut self, point: P, value: V) -> Result<PointId, Box<dyn std::error::Error>> {
+        let point_id = self.hnsw.insert(point, 100, Some(Heuristic::default()));
+        self.values.push(value);
+        Ok(point_id)
+    }
 }
 
 pub struct MapItem<'a, P, V> {
@@ -394,6 +400,55 @@ where
     pub fn get(&self, i: usize, search: &Search) -> Option<Item<'_, P>> {
         Some(Item::new(search.nearest.get(i).copied()?, self))
     }
+
+    pub fn insert(
+        &mut self,
+        point: P,
+        ef_construction: usize,
+        heuristic: Option<Heuristic>,
+    ) -> PointId {
+        let new_pid = self.points.len();
+        let new_point_id = PointId(new_pid as u32);
+
+        self.points.push(point);
+        self.zero.push(ZeroNode::default());
+
+        let zeros = self
+            .zero
+            .iter()
+            .map(|z| RwLock::new(z.clone()))
+            .collect::<Vec<_>>();
+
+        let top = if self.layers.is_empty() {
+            LayerId(0)
+        } else {
+            LayerId(self.layers.len())
+        };
+
+        let construction = Construction {
+            zero: zeros.as_slice(),
+            pool: SearchPool::new(self.points.len()),
+            top,
+            points: self.points.as_slice(),
+            heuristic,
+            ef_construction,
+            #[cfg(feature = "indicatif")]
+            progress: None,
+            #[cfg(feature = "indicatif")]
+            done: AtomicUsize::new(0),
+        };
+
+        let new_layer = construction.top;
+        construction.insert(new_point_id, new_layer, &self.layers);
+
+        self.zero = construction
+            .zero
+            .iter()
+            .map(|node| node.read().clone())
+            .collect();
+
+        new_point_id
+    }
 }
 
 pub struct Item<'a, P> {

instant-distance/tests/all.rs

@@ -96,3 +96,85 @@ impl instant_distance::Point for Point {
         ((self.0 - other.0).powi(2) + (self.1 - other.1).powi(2)).sqrt()
     }
 }
+
+#[test]
+#[allow(clippy::float_cmp, clippy::approx_constant)]
+fn incremental_insert() {
+    let points = (0..4)
+        .map(|i| Point(i as f32, i as f32))
+        .collect::<Vec<_>>();
+    let values = vec!["zero", "one", "two", "three"];
+    let seed = ThreadRng::default().gen::<u64>();
+    let builder = Builder::default().seed(seed);
+
+    let mut map = builder.build(points, values);
+
+    map.insert(Point(4.0, 4.0), "four").expect("Should insert");
+
+    let mut search = Search::default();
+
+    for (i, item) in map.search(&Point(4.0, 4.0), &mut search).enumerate() {
+        match i {
+            0 => {
+                assert_eq!(item.distance, 0.0);
+                assert_eq!(item.value, &"four");
+            }
+            1 => {
+                assert_eq!(item.distance, 1.4142135);
+                assert!(item.value == &"three");
+            }
+            2 => {
+                assert_eq!(item.distance, 2.828427);
+                assert!(item.value == &"two");
+            }
+            3 => {
+                assert_eq!(item.distance, 4.2426405);
+                assert!(item.value == &"one");
+            }
+            4 => {
+                assert_eq!(item.distance, 5.656854);
+                assert!(item.value == &"zero");
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    // Note 
+    // This has the same expected results as incremental_insert but builds
+    // the whole map in one go. Only here for comparison.
+    {
+        let points = (0..5)
+            .map(|i| Point(i as f32, i as f32))
+            .collect::<Vec<_>>();
+        let values = vec!["zero", "one", "two", "three", "four"];
+        let seed = ThreadRng::default().gen::<u64>();
+        let builder = Builder::default().seed(seed);
+        let map = builder.build(points, values);
+        let mut search = Search::default();
+        for (i, item) in map.search(&Point(4.0, 4.0), &mut search).enumerate() {
+            match i {
+                0 => {
+                    assert_eq!(item.distance, 0.0);
+                    assert_eq!(item.value, &"four");
+                }
+                1 => {
+                    assert_eq!(item.distance, 1.4142135);
+                    assert!(item.value == &"three");
+                }
+                2 => {
+                    assert_eq!(item.distance, 2.828427);
+                    assert!(item.value == &"two");
+                }
+                3 => {
+                    assert_eq!(item.distance, 4.2426405);
+                    assert!(item.value == &"one");
+                }
+                4 => {
+                    assert_eq!(item.distance, 5.656854);
+                    assert!(item.value == &"zero");
+                }
+                _ => unreachable!(),
+            }
+        }
+    }
+}