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 +1,77 @@
+/*
+ * 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;
+using System.Collections.Generic;
+
+namespace QuantConnect.Util
+{
+    /// <summary>
+    /// Provides convenience of linq extension methods for <see cref="IEnumerator{T}"/> types
+    /// </summary>
+    public static class EnumeratorExtensions
+    {
+        /// <summary>
+        /// Filter the enumerator using the specified predicate
+        /// </summary>
+        public static IEnumerator<T> Where<T>(this IEnumerator<T> enumerator, Func<T, bool> predicate)
+        {
+            using (enumerator)
+            {
+                while (enumerator.MoveNext())
+                {
+                    if (predicate(enumerator.Current))
+                    {
+                        yield return enumerator.Current;
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Project the enumerator using the specified selector
+        /// </summary>
+        public static IEnumerator<TResult> Select<T, TResult>(this IEnumerator<T> enumerator, Func<T, TResult> selector)
+        {
+            using (enumerator)
+            {
+                while (enumerator.MoveNext())
+                {
+                    yield return selector(enumerator.Current);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Project the enumerator using the specified selector
+        /// </summary>
+        public static IEnumerator<TResult> SelectMany<T, TResult>(this IEnumerator<T> enumerator, Func<T, IEnumerator<TResult>> selector)
+        {
+            using (enumerator)
+            {
+                while (enumerator.MoveNext())
+                {
+                    using (var inner = selector(enumerator.Current))
+                    {
+                        while (inner.MoveNext())
+                        {
+                            yield return inner.Current;
+                        }
+                    }
+                }
+            }
+        }
+    }
+}