91 lines
2.6 KiB
C#
91 lines
2.6 KiB
C#
using System;
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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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using System.Runtime.InteropServices;
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using System.Text;
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using System.Threading.Tasks;
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using System.Xml.Serialization;
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namespace StgSharp.Collections
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{
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/// <summary>
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/// Part of a collection. This contains a direct reference to origin collection,
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/// so all change to origin collection will be reflected in this object.
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/// </summary>
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/// <typeparam name="T"></typeparam>
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public struct ListSegment<T> : ICollection<T>
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{
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private List<T> _collection;
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private int _begin;
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private int _length;
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public ListSegment(List<T> collection, int begin, int length)
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{
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ArgumentNullException.ThrowIfNull(collection);
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ArgumentOutOfRangeException.ThrowIfLessThan(begin, 0);
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ArgumentOutOfRangeException.ThrowIfLessThan(length, 0);
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ArgumentOutOfRangeException.ThrowIfLessThan(begin + length, collection.Count);
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_collection = collection;
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_begin = begin;
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_length = length;
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}
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public int Count => _length;
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public bool IsReadOnly => true;
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public T this[int indexValue]
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{
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get {
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ArgumentOutOfRangeException.ThrowIfLessThan(indexValue, 0);
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ArgumentOutOfRangeException.ThrowIfGreaterThanOrEqual(indexValue, _length);
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return _collection[indexValue + _begin];
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}
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}
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void ICollection<T>.Add(T item)
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{
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throw new NotSupportedException();
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}
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void ICollection<T>.Clear()
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{
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throw new NotSupportedException();
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}
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public bool Contains(T item)
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{
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var index= _collection.IndexOf(item);
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return index >= _begin && index < _length + index;
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}
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public void CopyTo(T[] array, int arrayIndex)
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{
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ArgumentNullException.ThrowIfNull(array);
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var span = CollectionsMarshal.AsSpan<T>(_collection).Slice(_begin, _length);
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var target = new Span<T>(array, arrayIndex,_length);
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span.CopyTo(target);
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}
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public IEnumerator<T> GetEnumerator()
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{
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for (int i = _begin; i < _length; i++)
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{
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yield return this[i];
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}
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}
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bool ICollection<T>.Remove(T item)
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{
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throw new NotSupportedException();
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}
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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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