Predicate
Provides extension methods for type Predicate<T> and
predefined predicates.
using System;
using System.Runtime.CompilerServices;
namespace DotNext
{
[System.Runtime.CompilerServices.NullableContext(1)]
[System.Runtime.CompilerServices.Nullable(0)]
public static class Predicate
{
[System.Runtime.CompilerServices.Nullable(0)]
private static class TruePredicate<[System.Runtime.CompilerServices.Nullable(2)] T>
{
internal static readonly Predicate<T> Value = AlwaysTrue;
private static bool AlwaysTrue(T value)
{
return true;
}
}
[System.Runtime.CompilerServices.Nullable(0)]
private static class FalsePredicate<[System.Runtime.CompilerServices.Nullable(2)] T>
{
internal static readonly Predicate<T> Value = AlwaysFalse;
private static bool AlwaysFalse(T value)
{
return false;
}
}
[System.Runtime.CompilerServices.Nullable(0)]
private static class IsNullPredicate<T> where T : class
{
internal static readonly Predicate<T> Value = ObjectExtensions.IsNull;
}
[System.Runtime.CompilerServices.Nullable(0)]
private static class IsNotNullPredicate<T> where T : class
{
internal static readonly Predicate<T> Value = ObjectExtensions.IsNotNull;
}
[System.Runtime.CompilerServices.NullableContext(0)]
private static class HasValuePredicate<T> where T : struct
{
[System.Runtime.CompilerServices.Nullable(new byte[] {
1,
0
})]
internal static readonly Predicate<T?> Value = HasValue;
private static bool HasValue(T? nullable)
{
return nullable.HasValue;
}
}
public static Predicate<T> IsNull<T>() where T : class
{
return IsNullPredicate<T>.Value;
}
public static Predicate<T> IsNotNull<T>() where T : class
{
return IsNotNullPredicate<T>.Value;
}
[System.Runtime.CompilerServices.NullableContext(0)]
[return: System.Runtime.CompilerServices.Nullable(new byte[] {
1,
0
})]
public static Predicate<T?> HasValue<T>() where T : struct
{
return HasValuePredicate<T>.Value;
}
public static Predicate<T> True<[System.Runtime.CompilerServices.Nullable(2)] T>()
{
return TruePredicate<T>.Value;
}
public static Predicate<T> False<[System.Runtime.CompilerServices.Nullable(2)] T>()
{
return FalsePredicate<T>.Value;
}
public static Func<T, bool> AsFunc<[System.Runtime.CompilerServices.Nullable(2)] T>(this Predicate<T> predicate)
{
return predicate.ChangeType<Func<T, bool>>();
}
public static Converter<T, bool> AsConverter<[System.Runtime.CompilerServices.Nullable(2)] T>(this Predicate<T> predicate)
{
return predicate.ChangeType<Converter<T, bool>>();
}
private static bool Negate<[System.Runtime.CompilerServices.Nullable(2)] T>(this Predicate<T> predicate, T obj)
{
return !predicate(obj);
}
public static Predicate<T> Negate<[System.Runtime.CompilerServices.Nullable(2)] T>(this Predicate<T> predicate)
{
return predicate.Negate<T>;
}
public static Predicate<T> Or<[System.Runtime.CompilerServices.Nullable(2)] T>(this Predicate<T> left, Predicate<T> right)
{
return delegate(T input) {
if (!left(input))
return right(input);
return true;
};
}
public static Predicate<T> And<[System.Runtime.CompilerServices.Nullable(2)] T>(this Predicate<T> left, Predicate<T> right)
{
return delegate(T input) {
if (left(input))
return right(input);
return false;
};
}
public static Predicate<T> Xor<[System.Runtime.CompilerServices.Nullable(2)] T>(this Predicate<T> left, Predicate<T> right)
{
return (T input) => left(input) ^ right(input);
}
[return: System.Runtime.CompilerServices.Nullable(0)]
public static Result<bool> TryInvoke<[System.Runtime.CompilerServices.Nullable(2)] T>(this Predicate<T> predicate, T obj)
{
try {
return predicate(obj);
} catch (Exception error) {
return new Result<bool>(error);
}
}
[return: System.Runtime.CompilerServices.Nullable(new byte[] {
0,
1
})]
public static ValueFunc<T, bool> AsValueFunc<[System.Runtime.CompilerServices.Nullable(2)] T>(this Predicate<T> predicate, bool wrap = false)
{
return new ValueFunc<T, bool>(Unsafe.As<Func<T, bool>>(predicate), wrap);
}
}
}