127 lines
4.0 KiB
C#
127 lines
4.0 KiB
C#
using Pcg;
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namespace PkmnLib.Static.Utils;
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/// <summary>
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/// Wrapper interface for getting random numbers.
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/// </summary>
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public interface IRandom
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{
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/// <summary>
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/// Get a random integer between min and max.
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/// </summary>
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/// <param name="min">The minimum value (inclusive).</param>
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/// <param name="max">The maximum value (exclusive).</param>
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/// <returns>A random integer that is greater than or equal to min and less than max.</returns>
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public int GetInt(int min, int max);
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/// <summary>
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/// Get a random integer between 0 and max.
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/// </summary>
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/// <param name="max">The maximum value (exclusive).</param>
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/// <returns>A random integer that is greater than or equal to 0 and less than max.</returns>
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public int GetInt(int max);
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/// <summary>
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/// Get a random integer between 0 and <see cref="int.MaxValue"/>.
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/// </summary>
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/// <returns>A random integer that is greater than or equal to 0 and less than <see cref="int.MaxValue"/>.</returns>
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public int GetInt();
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/// <summary>
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/// Get a random float that is greater than or equal to 0.0 and less than 1.0.
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/// </summary>
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/// <returns>A random float that is greater than or equal to 0.0 and less than 1.0.</returns>
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public float GetFloat();
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/// <summary>
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/// Get a random float that is greater than or equal to min and less than max.
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/// </summary>
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/// <param name="min">The minimum value (inclusive).</param>
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/// <param name="max">The maximum value (exclusive).</param>
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/// <returns>A random float that is greater than or equal to min and less than max.</returns>
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public float GetFloat(float min, float max);
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/// <summary>
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/// Get a random boolean. 50% chance of being true.
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/// </summary>
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public bool GetBool();
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/// <summary>
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/// Get a random element from the given list.
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/// </summary>
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public T OneOf<T>(IReadOnlyList<T> list);
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}
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/// <inheritdoc />
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public class RandomImpl : IRandom
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{
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private readonly PcgRandom _random;
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/// <summary>
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/// Creates a new instance that uses the given <see cref="PcgRandom"/> instance as its source of randomness.
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/// </summary>
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public RandomImpl(PcgRandom random)
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{
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_random = random;
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}
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/// <summary>
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/// Creates a new instance that uses the given seed to create a new <see cref="PcgRandom"/> instance.
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/// </summary>
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public RandomImpl(int seed)
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{
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_random = new PcgRandom(seed);
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}
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/// <summary>
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/// Creates a new instance that uses a new <see cref="PcgRandom"/> instance.
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/// </summary>
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public RandomImpl()
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{
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_random = new PcgRandom();
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}
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/// <inheritdoc />
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public int GetInt(int min, int max) => _random.Next(min, max);
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/// <inheritdoc />
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public int GetInt(int max) => _random.Next(max);
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/// <inheritdoc />
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public int GetInt() => _random.Next();
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/// <inheritdoc />
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public float GetFloat() => (float)_random.NextDouble();
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/// <inheritdoc />
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public float GetFloat(float min, float max) => (float)(_random.NextDouble() * (max - min) + min);
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/// <inheritdoc />
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public bool GetBool() => _random.Next(2) == 1;
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/// <inheritdoc />
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public T OneOf<T>(IReadOnlyList<T> list)
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{
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if (list.Count == 0)
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throw new ArgumentException("List cannot be empty.", nameof(list));
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return list[GetInt(list.Count)];
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}
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/// <summary>
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/// Generates a new random <see cref="Guid"/>.
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/// </summary>
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/// <remarks>
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/// The goal of this method is to create a new unique identifier that can be used for various purposes,
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/// without having to rely on the system's built-in GUID generation. The built-in GUID generation
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/// can be slow (see also: https://github.com/dotnet/runtime/issues/13628)
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/// </remarks>
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public Guid NewGuid()
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{
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var guidBytes = GuidCache.Value.AsSpan();
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_random.NextBytes(guidBytes);
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return new Guid(guidBytes);
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}
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private static readonly ThreadLocal<byte[]> GuidCache = new(() => new byte[16]);
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} |