diff -r 7732013ce64c -r c5a6e8566425 rust/hedgewars-server/src/core/indexslab.rs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rust/hedgewars-server/src/core/indexslab.rs	Tue May 28 19:04:18 2019 +0300
@@ -0,0 +1,71 @@
+use std::{
+    iter,
+    mem::replace,
+    ops::{Index, IndexMut},
+};
+
+pub struct IndexSlab<T> {
+    data: Vec<Option<T>>,
+}
+
+impl<T> IndexSlab<T> {
+    pub fn new() -> Self {
+        Self { data: Vec::new() }
+    }
+
+    pub fn with_capacity(capacity: usize) -> Self {
+        Self {
+            data: Vec::with_capacity(capacity),
+        }
+    }
+
+    pub fn insert(&mut self, index: usize, value: T) {
+        if index >= self.data.len() {
+            self.data.reserve(index - self.data.len() + 1);
+            self.data.extend((self.data.len()..index).map(|_| None));
+            self.data.push(Some(value))
+        } else {
+            self.data[index] = Some(value);
+        }
+    }
+
+    pub fn contains(&self, index: usize) -> bool {
+        self.data.get(index).and_then(|x| x.as_ref()).is_some()
+    }
+
+    pub fn remove(&mut self, index: usize) -> Option<T> {
+        if let Some(x) = self.data.get_mut(index) {
+            replace(x, None)
+        } else {
+            None
+        }
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = (usize, &T)> {
+        self.data
+            .iter()
+            .enumerate()
+            .filter_map(|(index, opt)| opt.as_ref().and_then(|x| Some((index, x))))
+    }
+
+    pub fn iter_mut(&mut self) -> impl Iterator<Item = (usize, &mut T)> {
+        self.data
+            .iter_mut()
+            .enumerate()
+            .filter_map(|(index, opt)| opt.as_mut().and_then(|x| Some((index, x))))
+    }
+}
+
+impl<T> Index<usize> for IndexSlab<T> {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        self.data[index].as_ref().unwrap()
+    }
+}
+
+impl<T> IndexMut<usize> for IndexSlab<T> {
+    fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+        self.data[index].as_mut().unwrap()
+    }
+}