wehub-resource-sync
111 lines
3.5 KiB
C#
111 lines
3.5 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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namespace QuantConnect.Util
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{
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/// <summary>
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/// Provides an implementation of an add-only fixed length, unique queue system
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/// </summary>
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public class FixedSizeHashQueue<T> : IEnumerable<T>
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{
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private readonly int _size;
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private readonly Queue<T> _queue;
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private readonly HashSet<T> _hash;
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/// <summary>
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/// Initializes a new instance of the <see cref="FixedSizeHashQueue{T}"/> class
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/// </summary>
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/// <param name="size">The maximum number of items to hold</param>
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public FixedSizeHashQueue(int size)
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{
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_size = size;
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_queue = new Queue<T>(size);
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_hash = new HashSet<T>();
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}
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/// <summary>
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/// Returns true if the item was added and didn't already exists
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/// </summary>
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public bool Add(T item)
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{
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if (_hash.Add(item))
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{
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_queue.Enqueue(item);
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if (_queue.Count > _size)
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{
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// remove the item from both
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_hash.Remove(_queue.Dequeue());
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}
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return true;
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}
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return false;
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}
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/// <summary>
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/// Tries to inspect the first item in the queue
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/// </summary>
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public bool TryPeek(out T item)
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{
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return _queue.TryPeek(out item);
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}
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/// <summary>
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/// Dequeues and returns the next item in the queue
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/// </summary>
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public T Dequeue()
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{
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var item = _queue.Dequeue();
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_hash.Remove(item);
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return item;
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}
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/// <summary>
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/// Returns true if the specified item exists in the collection
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/// </summary>
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public bool Contains(T item)
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{
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return _hash.Contains(item);
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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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/// A <see cref="T:System.Collections.Generic.IEnumerator`1"/> 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<T> GetEnumerator()
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{
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return _queue.GetEnumerator();
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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 <see cref="T:System.Collections.IEnumerator"/> 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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