64 lines
1.7 KiB
C#
64 lines
1.7 KiB
C#
using System.Runtime.CompilerServices;
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namespace PerfectNumbers.Core;
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public sealed class FixedCapacityStack<T>
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{
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[ThreadStatic]
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private static FixedCapacityArrayPool<T>? _arrayPool;
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public int Count = 0;
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private T[] _items;
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private int _capacity;
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public FixedCapacityStack(int capacity)
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{
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_arrayPool ??= new(PerfectNumberConstants.DefaultPoolCapacity);
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_items = _arrayPool.Value.Rent(capacity);
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_capacity = capacity;
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}
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public int Capacity
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{
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[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
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get => _capacity;
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[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
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set
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{
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if (value < _capacity)
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{
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_arrayPool!.Value.Return(_items);
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_items = _arrayPool.Value.Rent(value);
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_capacity = value;
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}
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}
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}
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/// <summary>
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/// Sets the no. of elements on the stack to 0. It doesn't clear the internal memory buffer from unused references.
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/// </summary>
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[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
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public void Clear() => Count = 0;
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/// <summary>
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/// Pops and returns the first element from the stack. It doesn't clear the internal memory buffer from unused references.
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/// </summary>
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/// <returns>The first element on the stack or null / default when the stack is empty.
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[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
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public T? Pop() => Count > 0 ? _items[Count--] : default;
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[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
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public void Push(T item)
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{
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int newCount = Count + 1;
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T[] items = _items;
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if (newCount < items.Length)
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{
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items[newCount] = item;
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Count = newCount;
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}
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}
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}
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