52 lines
2.4 KiB
C#
52 lines
2.4 KiB
C#
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using System.Diagnostics.CodeAnalysis;
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namespace SJK.Functional;
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public interface IOption<T> : IEquatable<IOption<T>>
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{
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/// <summary>
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/// Applies a function to the contained value if it exists (is not None), otherwise applies a default function.
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/// </summary>
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/// <param name="onSome">Function to apply if the option contains a value.</param>
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/// <param name="onNone">Function to apply if the option does not contain a value.</param>
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/// <returns>The result of applying either the onSome or onNone function.</returns>
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TResult Match<TResult>(Func<T, TResult> onSome, Func<TResult> onNone);
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void Match(Action<T> onSome,Action onNone);
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/// <summary>
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/// Chains operations on the contained value using a function that returns an option.
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/// </summary>
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/// <param name="f">A function that takes the contained value and returns an option.</param>
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/// <returns>An option resulting from applying the function f to the contained value.</returns>
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IOption<TResult> Bind<TResult>(Func<T, IOption<TResult>> f);
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/// <summary>
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/// Maps a function over the contained value if it exists (is not None).
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/// </summary>
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/// <param name="f">The function to apply to the contained value.</param>
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/// <returns>An option containing the result of applying f to the contained value.</returns>
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IOption<TResult> Map<TResult>(Func<T, TResult> f);
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/// <summary>
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/// Returns the contained value if it exists (is not None), otherwise returns the provided default value.
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/// </summary>
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/// <param name="aDefault">The default value to return if the option does not contain a value.</param>
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/// <returns>The contained value or the default value.</returns>
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T Or(T aDefault);
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/// <summary>
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/// Returns the contained value if it exists (is not None), otherwise calls the provided default function.
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/// </summary>
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/// <param name="aDefault">The default value to return if the option does not contain a value.</param>
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/// <returns>The contained value or the default value.</returns>
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T Or(Func<T> aDefault);
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/// <summary>
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/// Checks if the option contains a value (is not None) and outputs it if true.
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/// </summary>
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/// <param name="value">An out parameter that will be assigned the contained value if it exists.</param>
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/// <returns>true if the option contains a value; false otherwise.</returns>
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bool HasValue([NotNullWhen(true)]out T? value);
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// [Obsolete]
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bool HasValue();
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}
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