Fix take llast

src/lib/Modifiers/TakeLast.vala

@@ -1,3 +1,4 @@
+using Invercargill.DataStructures;
 namespace Invercargill.Modifiers {
 
     public class TakeLast<T> : Enumerable<T> {
@@ -21,59 +22,22 @@ namespace Invercargill.Modifiers {
         }
 
         public override Tracker<T> get_tracker() {
-            var tracker = input.get_tracker();
-            DataStructures.RingBuffer<T>? buffer = null;
-            var index = 0;
-            var input_exhausted = false;
-            var output_index = 0;
-            var output_started = false;
-            var actual_count = 0;
-            
-            return new AdvanceTracker<T>((out obj) => {
-                obj = null;
-                
-                // First, fill the buffer with all items from the input
-                if (!input_exhausted) {
-                    // Initialize buffer with the requested size
-                    buffer = new DataStructures.RingBuffer<T>((uint)n_items);
-                    
-                    while(tracker.has_next()) {
-                        var item = tracker.get_next();
-                        
-                        // Add item to buffer, overwriting oldest if buffer is full
-                        buffer.set((uint)index, item);
-                        index = (index + 1) % n_items;
-                        
-                        // Track how many items we've actually seen
-                        if (actual_count < n_items) {
-                            actual_count++;
-                        }
-                    }
-                    input_exhausted = true;
-                    
-                    // Set the output index to the oldest item
-                    if (actual_count == n_items) {
-                        // Buffer is full, oldest item is at current index
-                        output_index = index;
-                    } else {
-                        // Buffer not full, start from beginning
-                        output_index = 0;
-                    }
-                }
-                
-                // After exhausting the input, return items from the buffer
-                if (!output_started) {
-                    output_started = true;
-                }
-                
-                if(output_index < actual_count) {
-                    obj = buffer.get((uint)output_index);
-                    output_index++;
-                    return true;
-                }
-                
-                return false;
-            });
+            var buffer = new RingBuffer<T>(n_items);
+            var write_index = n_items;
+            foreach (var item in input) {
+                non_error(() => buffer[write_index] = item);
+                write_index++;
+            }
+
+            if(write_index - n_items <= n_items) {
+                return buffer.take(write_index).get_tracker();
+            }
+
+            var read_index = write_index - n_items;
+            return new LambdaTracker<T>(
+                () => read_index < write_index,
+                () => buffer.get_or_default(read_index++)
+            );
         }
     }