78 lines
2.9 KiB
C#
78 lines
2.9 KiB
C#
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// Animancer // https://kybernetik.com.au/animancer // Copyright 2018-2023 Kybernetik //
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using System.Collections.Generic;
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namespace Animancer
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{
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/// <summary>A simple stack implementation that tracks an active index without actually adding or removing objects.</summary>
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/// https://kybernetik.com.au/animancer/api/Animancer/LazyStack_1
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///
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public class LazyStack<T> where T : new()
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{
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/************************************************************************************************************************/
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/// <summary>The underlying collection of objects.</summary>
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/// <remarks>
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/// This is not a <see cref="Stack{T}"/> because that class comes from a different assembly that might not
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/// otherwise need to be included in builds, so using a <see cref="List{T}"/> can slightly reduce build size.
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/// </remarks>
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private readonly List<T> Stack;
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/// <summary>The index of the <see cref="Current"/> object in the <see cref="Stack"/>.</summary>
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private int _CurrentIndex = -1;
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/// <summary>The object currently on the top of the stack.</summary>
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public T Current { get; private set; }
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/************************************************************************************************************************/
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/// <summary>Creates a new <see cref="LazyStack{T}"/> with a default internal list capacity of 16.</summary>
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public LazyStack()
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{
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Stack = new List<T>();
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}
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/// <summary>Creates a new <see cref="LazyStack{T}"/> with the specified internal list capacity.</summary>
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public LazyStack(int capacity)
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{
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Stack = new List<T>(capacity);
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for (int i = 0; i < capacity; i++)
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Stack[i] = new T();
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}
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/************************************************************************************************************************/
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/// <summary>Moves to the next object in the stack.</summary>
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public T Increment()
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{
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_CurrentIndex++;
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if (_CurrentIndex == Stack.Count)
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{
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Current = new T();
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Stack.Add(Current);
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}
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else
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{
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Current = Stack[_CurrentIndex];
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}
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return Current;
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}
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/************************************************************************************************************************/
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/// <summary>Moves to the previous object in the stack.</summary>
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public void Decrement()
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{
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_CurrentIndex--;
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if (_CurrentIndex >= 0)
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Current = Stack[_CurrentIndex];
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else
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Current = default;
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}
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/************************************************************************************************************************/
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}
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}
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