Use an iterator and extend.

Author: ltratt

src/lib.rs

@@ -183,11 +183,12 @@ fn compress<T: Clone + Copy + PartialEq>(
         // `tmp` contains `(index, non-empty-value)` pairs that we can then pass to `fits`. Because
         // this is such a tight loop, we reuse the same `Vec` to avoid repeated allocations.
         tmp.clear();
-        for (i, v) in vec[s * row_length..(s + 1) * row_length].iter().enumerate() {
-            if *v != empty_val {
-                tmp.push((i, v));
-            }
-        }
+        tmp.extend(
+            vec[s * row_length..(s + 1) * row_length]
+                .iter()
+                .enumerate()
+                .filter(|(_, v)| **v != empty_val),
+        );
 
         let mut d = 0; // displacement value
         loop {