paulirwin commented on code in PR #1066:
URL: https://github.com/apache/lucenenet/pull/1066#discussion_r2354170619
##########
src/Lucene.Net/Support/CastingListAdapter.cs:
##########
@@ -0,0 +1,75 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Lucene.Net.Support
+{
+ /*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+ /// <summary>
+ /// LUCENENET specific class used to adapt a <see cref="IList{T}"/> to one
with a different type parameter
+ /// where the elements are cast to the new type where needed.
+ /// </summary>
+ /// <typeparam name="T">The type of the elements in the original
list.</typeparam>
+ /// <typeparam name="U">The type of the elements in the adapted
list.</typeparam>
+ internal class CastingListAdapter<T, U> : IList<U>
+ where T : U
+ {
+ private readonly IList<T> list;
+
+ public CastingListAdapter(IList<T> list)
+ {
+ this.list = list;
+ }
+
+ public U this[int index]
+ {
+ get => list[index];
+ set => list[index] = (T)value;
+ }
+
+ public int Count => list.Count;
+
+ public bool IsReadOnly => list.IsReadOnly;
+
+ public void Add(U item) => list.Add((T)item);
+
+ public void Clear() => list.Clear();
+
+ public bool Contains(U item) => list.Contains((T)item);
+
+ public void CopyTo(U[] array, int arrayIndex)
+ {
+ for (int i = 0; i < list.Count; i++)
+ {
+ array[arrayIndex + i] = list[i];
+ }
+ }
+
+ public IEnumerator<U> GetEnumerator() =>
list.Cast<U>().GetEnumerator();
Review Comment:
Fixed, and also made CastingEnumeratorAdapter a readonly struct to reduce an
allocation. In most cases it still will likely be boxed, but there might be
some runtime optimizations that could take advantage of that. At a minimum, it
can't hurt anyways.
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