lab 4

lectures/04/alist/src/main.rs

@@ -0,0 +1,42 @@
+// for demo purposes
+struct Alist<K, V>(Vec<(K, V)>); // newtype pattern
+
+impl<K, V> Alist<K, V> {
+    fn new() -> Self {
+        Self(Vec::new())
+    }
+
+    fn insert(&mut self, key: K, value: V) {
+        self.0.push((key, value));
+    }
+
+    fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    fn into_iter(self) -> std::vec::IntoIter<(K, V)> {
+        self.0.into_iter()
+    }
+}
+
+use std::ops::Deref;
+
+impl<K, V> Deref for Alist<K, V> {
+    type Target = [(K, V)];
+
+    fn deref(&self) -> &Self::Target {
+        self.0.deref()
+    }
+}
+
+fn main() {
+    let mut l = Alist::new();
+    for (x, y) in [(1, 2), (3, 4), (5, 6)] {
+        l.insert(x, y);
+    }
+
+    let mut iter = l.iter();
+    while let Some((k, v)) = iter.next() {
+        println!("{k}: {v}");
+    }
+}