Tried out Google's AI response to the question of a C++ spatial hash and it kind of came close. This took some massaging but it could work.

meson.build

@@ -38,4 +38,9 @@ myecstest = executable('myecstest', [
   ],
   dependencies: dependencies)
 
+collider = executable('collider', [
+  './scratchpad/collider.cpp'
+  ],
+  dependencies: dependencies)
+
 test('tests', runtests)

scratchpad/collider.cpp

@@ -0,0 +1,70 @@
+#include <iostream>
+#include <vector>
+#include <unordered_map>
+
+struct Point {
+    int x, y;
+
+    bool operator==(const Point& other) const {
+      return other.x == x && other.y == y;
+    }
+};
+
+struct Object {
+    Point position;
+    // Add other object data as needed
+};
+
+struct PointHash {
+  size_t operator()(const Point& p) const {
+    return std::hash<int>()(p.x) ^ std::hash<int>()(p.y);
+  }
+};
+
+class SpatialHashTable {
+public:
+    SpatialHashTable() {}
+
+    void insert(Object* obj) {
+        table[obj->position].push_back(obj);
+    }
+
+    std::vector<Object*> getNearbyObjects(Point position) {
+        std::vector<Object*> result;
+        Point cell = position;
+
+        // Check the current cell and its 8 neighbors
+        for (int x = cell.x - 1; x <= cell.x + 1; x++) {
+            for (int y = cell.y - 1; y <= cell.y + 1; y++) {
+                Point neighborCell = {x, y};
+                auto it = table.find(neighborCell);
+                if (it != table.end()) {
+                    result.insert(result.end(), it->second.begin(), it->second.end());
+                }
+            }
+        }
+
+        return result;
+    }
+
+private:
+    std::unordered_map<Point, std::vector<Object*>, PointHash> table;
+};
+
+int main() {
+    SpatialHashTable hashTable;
+    Object obj1 = {{5, 5}};
+    Object obj2 = {{15, 15}};
+    Object bomb = {{25, 25}};
+
+    hashTable.insert(&obj1);
+    hashTable.insert(&obj2);
+    hashTable.insert(&bomb);
+
+    std::vector<Object*> nearby = hashTable.getNearbyObjects({24, 24});
+    for (Object* obj : nearby) {
+        std::cout << obj->position.x << ", " << obj->position.y << std::endl;
+    }
+
+    return 0;
+}