93 lines
2.5 KiB
C#
93 lines
2.5 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Threading;
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using System.Threading.Tasks;
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namespace FruityFoundation.Base.Structures;
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public static class MaybeExtensions
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{
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public static Maybe<T> FirstOrEmpty<T>(this IEnumerable<T> collection)
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{
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using var enumerator = collection.GetEnumerator();
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return !enumerator.MoveNext() ? Maybe.Empty<T>() : enumerator.Current;
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}
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public static Maybe<T> FirstOrEmpty<T>(this IEnumerable<T> collection, Func<T, bool> pred)
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{
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foreach (var item in collection)
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if (pred(item))
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return item;
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return Maybe.Empty<T>();
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}
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public static async ValueTask<Maybe<T>> FirstOrEmptyAsync<T>(this IAsyncEnumerable<T> source, CancellationToken cancellationToken = default)
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{
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if (source is IList<T> { Count: > 0 } list)
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return Maybe.Create(list[0]);
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await using var e = source
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.ConfigureAwait(false)
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.WithCancellation(cancellationToken)
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.GetAsyncEnumerator();
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if (await e.MoveNextAsync())
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return e.Current;
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return Maybe.Empty<T>();
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}
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public static async ValueTask<Maybe<T>> FirstOrEmptyAsync<T>(this IAsyncEnumerable<T> source, Func<T, bool> predicate, CancellationToken cancellationToken = default)
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{
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if (source is IList<T> { Count: > 0 } list)
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return list[0];
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await using var e = source
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.ConfigureAwait(false)
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.WithCancellation(cancellationToken)
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.GetAsyncEnumerator();
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while (await e.MoveNextAsync())
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{
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var value = e.Current;
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if (predicate(value))
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return value;
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}
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return Maybe.Empty<T>();
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}
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public static async ValueTask<Maybe<T>> FirstOrEmptyAsync<T>(this IAsyncEnumerable<T> source, Func<T, ValueTask<bool>> asyncPredicate, CancellationToken cancellationToken = default)
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{
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if (source is IList<T> { Count: > 0 } list)
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return list[0];
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await using var e = source
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.ConfigureAwait(false)
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.WithCancellation(cancellationToken)
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.GetAsyncEnumerator();
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while (await e.MoveNextAsync())
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{
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var value = e.Current;
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if (await asyncPredicate(value).ConfigureAwait(false))
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return value;
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}
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return Maybe.Empty<T>();
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}
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public static Maybe<TValue> TryGetValue<TKey, TValue>(this IDictionary<TKey, TValue> dict, TKey key) =>
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dict.TryGetValue(key, out var value) ? Maybe.Create(value) : Maybe.Empty<TValue>();
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public static Maybe<TValue> TryGet<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dict, TKey key) =>
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dict.TryGetValue(key, out var value) ? Maybe.Create(value) : Maybe.Empty<TValue>();
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public static T? ToNullable<T>(this Maybe<T> item) where T : struct =>
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item.HasValue ? item.Value : null;
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}
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