wehub-resource-sync
82 lines
3.0 KiB
C#
82 lines
3.0 KiB
C#
/*
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* QUANTCONNECT.COM - Democratizing Finance, Empowering Individuals.
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* Lean Algorithmic Trading Engine v2.0. Copyright 2014 QuantConnect Corporation.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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using System.Collections;
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using System.Collections.Generic;
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using System.Linq;
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namespace QuantConnect.Util
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{
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/// <summary>
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/// Defines a list that casts the elements of a source list to a derived type.
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/// This is useful to avoid materializing another list after using, for example, the <see cref="Enumerable.Cast{TResult}(IEnumerable)"/> LINQ method.
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/// </summary>
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/// <typeparam name="TBase">The base type of the elements in the source enumerable.</typeparam>
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/// <typeparam name="TDerived">The type to cast the elements to.</typeparam>
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public class CastingEnumerable<TBase, TDerived> : IReadOnlyList<TDerived>
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where TDerived : class, TBase
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{
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private IReadOnlyList<TBase> _data;
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/// <summary>
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/// Gets the count of items in the enumerable.
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/// </summary>
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public int Count => _data.Count;
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/// <summary>
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/// Gets the element at the specified index.
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/// </summary>
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/// <param name="index">The zero-based index of the element to get.</param>
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/// <returns>The element at the specified index.</returns>
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public TDerived this[int index] => (TDerived)_data[index];
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/// <summary>
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/// Initializes a new instance of the <see cref="CastingEnumerable{TBase, TDerived}"/> class
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/// </summary>
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public CastingEnumerable(IReadOnlyList<TBase> data)
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{
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_data = data;
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}
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/// <summary>
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/// Returns an enumerator that iterates through the collection.
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/// </summary>
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/// <returns>
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/// An enumerator that can be used to iterate through the collection.
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/// </returns>
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/// <filterpriority>1</filterpriority>
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public IEnumerator<TDerived> GetEnumerator()
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{
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foreach (var item in _data)
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{
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yield return (TDerived)item;
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}
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}
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/// <summary>
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/// Returns an enumerator that iterates through a collection.
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/// </summary>
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/// <returns>
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/// An enumerator object that can be used to iterate through the collection.
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/// </returns>
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/// <filterpriority>2</filterpriority>
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IEnumerator IEnumerable.GetEnumerator()
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{
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return GetEnumerator();
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}
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}
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}
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