chore: import upstream snapshot with attribution

2026-07-13 13:02:50 +08:00
commit 0fc60fdcb1
5008 changed files with 910633 additions and 0 deletions
@@ -0,0 +1,81 @@
+/*
+ * QUANTCONNECT.COM - Democratizing Finance, Empowering Individuals.
+ * Lean Algorithmic Trading Engine v2.0. Copyright 2014 QuantConnect Corporation.
+ * 
+ * Licensed 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.
+ *
+*/
+
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace QuantConnect.Util
+{
+    /// <summary>
+    /// Defines a list that casts the elements of a source list to a derived type.
+    /// This is useful to avoid materializing another list after using, for example, the <see cref="Enumerable.Cast{TResult}(IEnumerable)"/> LINQ method.
+    /// </summary>
+    /// <typeparam name="TBase">The base type of the elements in the source enumerable.</typeparam>
+    /// <typeparam name="TDerived">The type to cast the elements to.</typeparam>
+    public class CastingEnumerable<TBase, TDerived> : IReadOnlyList<TDerived>
+        where TDerived : class, TBase
+    {
+        private IReadOnlyList<TBase> _data;
+
+        /// <summary>
+        /// Gets the count of items in the enumerable.
+        /// </summary>
+        public int Count => _data.Count;
+
+        /// <summary>
+        /// Gets the element at the specified index.
+        /// </summary>
+        /// <param name="index">The zero-based index of the element to get.</param>
+        /// <returns>The element at the specified index.</returns>
+        public TDerived this[int index] => (TDerived)_data[index];
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="CastingEnumerable{TBase, TDerived}"/> class
+        /// </summary>
+        public CastingEnumerable(IReadOnlyList<TBase> data)
+        {
+            _data = data;
+        }
+
+        /// <summary>
+        /// Returns an enumerator that iterates through the collection.
+        /// </summary>
+        /// <returns>
+        /// An enumerator that can be used to iterate through the collection.
+        /// </returns>
+        /// <filterpriority>1</filterpriority>
+        public IEnumerator<TDerived> GetEnumerator()
+        {
+            foreach (var item in _data)
+            {
+                yield return (TDerived)item;
+            }
+        }
+
+        /// <summary>
+        /// Returns an enumerator that iterates through a collection.
+        /// </summary>
+        /// <returns>
+        /// An enumerator object that can be used to iterate through the collection.
+        /// </returns>
+        /// <filterpriority>2</filterpriority>
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+    }
+}