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public static class NullableLinqExtensions
{
public static TTarget? Select<TSource, TTarget>(this TSource? t, Func<TSource, TTarget> selector)
where TSource : struct
where TTarget : struct
{
return t.HasValue ? (TTarget?) selector(t.Value) : null;
}
public static TSource? Where<TSource>(this TSource? t, Func<TSource, bool> predicate)
where TSource : struct
{
return t.HasValue && predicate(t.Value) ? t : null;
}
public static bool Contains<TSource>(this TSource? t, TSource v)
where TSource : struct
{
return t.Contains(v, EqualityComparer<TSource>.Default);
}
public static bool Contains<TSource>(this TSource? t, TSource v, IEqualityComparer<TSource> comparer)
where TSource : struct
{
return t.HasValue && comparer.Equals(t.Value, v);
}
public static bool Any<TSource>(this TSource? t)
where TSource : struct
{
return t.HasValue;
}
public static bool Any<TSource>(this TSource? t, Func<TSource, bool> predicate)
where TSource : struct
{
return t.HasValue && predicate(t.Value);
}
public static int Count<TSource>(this TSource? t)
where TSource : struct
{
return t.HasValue ? 1 : 0;
}
public static int Count<TSource>(this TSource? t, Func<TSource, bool> predicate)
where TSource : struct
{
return t.HasValue && predicate(t.Value) ? 1 : 0;
}
public static TSource First<TSource>(this TSource? t)
where TSource : struct
{
return t.Value;
}
public static TAccumulate Aggregate<TSource, TAccumulate>(
this TSource? t,
TAccumulate seed,
Func<TAccumulate, TSource, TAccumulate> combine)
where TSource : struct
{
return t.HasValue ? combine(seed, t.Value) : seed;
}
public static TSource FirstOrDefault<TSource>(this TSource? t)
where TSource : struct
{
return t.HasValue ? t.Value : default(TSource);
}
public static TTarget? SelectMany<TSource, TTarget>(this TSource? t, Func<TSource, TTarget?> selector)
where TSource : struct
where TTarget : struct
{
return t.HasValue ? selector(t.Value) : null;
}
public static TResult? SelectMany<TSource, TIntermediate, TResult>(this TSource? t, Func<TSource, TIntermediate?> selector, Func<TSource, TIntermediate, TResult> resultSelector)
where TSource : struct
where TIntermediate : struct
where TResult : struct
{
return t.SelectMany(selector).Select(it => resultSelector(t.Value, it));
}
}
void Lol(DateTime? maybeDateTime)
{
var maybeTomorrow =
from dt in maybeDateTime
where dt.DayOfWeek == DayOfWeek.Friday
select dt.AddDays(1);
maybeTomorrow.Any().Dump();
maybeTomorrow.Count().Dump();
}
TimeSpan? DifferencePerchance(DateTime? maybeThis, DateTime? maybeThat)
{
return
from dt1 in maybeThis
from dt2 in maybeThat
select (dt2 - dt1);
}
void Main()
{
DifferencePerchance(DateTime.Today, DateTime.Today.AddHours(1).AddMinutes(2)).Dump();
DifferencePerchance(DateTime.Today, null).Dump();
DateTime? whoknows1 = DateTime.Today;
DateTime? whoknows2 = null;
TimeSpan? maybetime1 = TimeSpan.FromDays(2);
TimeSpan? maybetime2 = null;
whoknows1.Contains(DateTime.Today).Dump();
whoknows2.Contains(DateTime.Today).Dump();
whoknows2.FirstOrDefault().Dump();
// whoknows2.First().Dump();
maybetime1.Aggregate(DateTime.Today, (dt, ts) => dt.Add(ts)).Dump();
maybetime2.Aggregate(DateTime.Today, (dt, ts) => dt.Add(ts)).Dump();
}
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