128 lines
3.2 KiB
C#
128 lines
3.2 KiB
C#
using System;
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namespace KitsuneCafe.Sys
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{
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public class Option
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{
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public static IOption<T> Some<T>(T value) => IOption<T>.Some(value);
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public static IOption<T> None<T>() => IOption<T>.None();
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}
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public interface IOption<T>
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{
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private static IOption<T> none = new None<T>();
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public abstract bool IsSome { get; }
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public static IOption<T> Some(T value) => new Some<T>(value);
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public static IOption<T> None() => none;
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public abstract T Unwrap();
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public abstract IOption<TResult> SelectMany<TResult>(Func<T, IOption<TResult>> func);
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public abstract IOption<TResult> Select<TResult>(Func<T, TResult> func);
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public abstract IOption<T> Where(Func<T, bool> predicate);
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public abstract TResult Match<TResult>(Func<T, TResult> ifSome, Func<TResult> ifNone);
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public abstract T UnwrapOrDefault(T defaultValue = default);
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public abstract T UnwrapOrElse(Func<T> func);
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public virtual IOption<T> Do(Action<T> func)
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{
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if (IsSome) { func(Unwrap()); }
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return this;
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}
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}
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public readonly struct Some<T> : IOption<T>
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{
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private readonly T value;
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public readonly bool IsSome => true;
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internal Some(T value)
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{
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this.value = value;
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}
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public IOption<TResult> SelectMany<TResult>(Func<T, IOption<TResult>> func)
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{
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return func(value);
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}
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public T Unwrap()
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{
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return value;
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}
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public IOption<TResult> Select<TResult>(Func<T, TResult> func)
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{
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return IOption<TResult>.Some(func(value));
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}
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public IOption<T> Where(Func<T, bool> predicate)
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{
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if (predicate(value))
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{
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return this;
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}
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return IOption<T>.None();
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}
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public TResult Match<TResult>(Func<T, TResult> ifSome, Func<TResult> ifNone)
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{
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return ifSome(value);
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}
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public T UnwrapOrDefault(T defaultValue = default)
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{
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return value;
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}
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public T UnwrapOrElse(Func<T> _func)
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{
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return value;
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}
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}
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public readonly struct None<T> : IOption<T>
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{
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public readonly bool IsSome => false;
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public IOption<TResult> SelectMany<TResult>(Func<T, IOption<TResult>> func)
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{
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return IOption<TResult>.None();
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}
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public T Unwrap()
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{
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throw new InvalidOperationException("Attempted to unwrap value of None.");
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}
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public IOption<TResult> Select<TResult>(Func<T, TResult> func)
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{
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return IOption<TResult>.None();
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}
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public IOption<T> Where(Func<T, bool> predicate)
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{
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return IOption<T>.None();
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}
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public TResult Match<TResult>(Func<T, TResult> ifSome, Func<TResult> ifNone)
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{
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return ifNone();
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}
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public T UnwrapOrDefault(T defaultValue = default)
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{
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return defaultValue;
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}
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public T UnwrapOrElse(Func<T> func)
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{
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return func();
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}
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}
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}
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