#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member
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using System;
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using System.Collections.Generic;
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using System.Runtime.CompilerServices;
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namespace Cysharp.Threading.Tasks.Internal
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{
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internal static class ArrayUtil
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{
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static void EnsureCapacity<T>(ref T[] array, int index)
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{
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if (array.Length <= index)
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{
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EnsureCore(ref array, index);
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}
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}
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// rare case, no inlining.
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[MethodImpl(MethodImplOptions.NoInlining)]
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static void EnsureCore<T>(ref T[] array, int index)
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{
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var newSize = array.Length * 2;
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var newArray = new T[(index < newSize) ? newSize : (index * 2)];
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Array.Copy(array, 0, newArray, 0, array.Length);
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array = newArray;
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}
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/// <summary>
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/// Optimizing utility to avoid .ToArray() that creates buffer copy(cut to just size).
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/// </summary>
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public static (T[] array, int length) Materialize<T>(IEnumerable<T> source)
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{
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if (source is T[] array)
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{
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return (array, array.Length);
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}
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var defaultCount = 4;
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if (source is ICollection<T> coll)
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{
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defaultCount = coll.Count;
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var buffer = new T[defaultCount];
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coll.CopyTo(buffer, 0);
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return (buffer, defaultCount);
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}
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else if (source is IReadOnlyCollection<T> rcoll)
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{
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defaultCount = rcoll.Count;
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}
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if (defaultCount == 0)
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{
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return (Array.Empty<T>(), 0);
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}
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{
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var index = 0;
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var buffer = new T[defaultCount];
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foreach (var item in source)
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{
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EnsureCapacity(ref buffer, index);
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buffer[index++] = item;
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}
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return (buffer, index);
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}
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}
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}
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}
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