/// <summary>
/// If <paramref name="a"/>.Value is present, returns an enumerable of that single value, otherwise an empty one
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="a"></param>
/// <returns></returns>
public static IEnumerable <T> ToEnumerable <T>(this Maybe <T> a)
{
if (a.IsSomething())
{
yield return(a.Value);
}
}
/// <summary>
/// Returns <paramref name="a"/> if its Value exists or returns <paramref name="b"/>
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="a"></param>
/// <param name="b"></param>
/// <returns></returns>
public static Maybe <T> Or <T>(this Maybe <T> a, Maybe <T> b)
{
if (a.IsSomething())
{
return(a);
}
return(b);
}
/// <summary>
/// Calls <paramref name="fn"/> if <paramref name="m"/> has value, otherwise does nothing
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="m"></param>
/// <param name="fn"></param>
/// <returns></returns>
public static Maybe <T> Do <T>(this Maybe <T> m, Action <T> fn)
{
if (m.IsSomething())
{
fn(m.Value);
}
return(m);
}
/// <summary>
/// Returns <paramref name="a"/> if its Value exists or returns <paramref name="b"/>()
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="a"></param>
/// <param name="b"></param>
/// <returns></returns>
public static Maybe <T> Or <T>(this Maybe <T> a, Func <Maybe <T> > b)
{
if (a.IsSomething())
{
return(a);
}
return(b());
}
/// <summary>
/// Returns <paramref name="a"/> if its Value exists or returns <paramref name="b"/>, wrapped as Maybe
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="a"></param>
/// <param name="b"></param>
/// <returns></returns>
public static Maybe <T> Or <T>(this Maybe <T> a, T b)
{
if (a.IsSomething())
{
return(a);
}
return(b.ToMaybe());
}
/// <summary>
/// Calls <paramref name="fn"/> if <paramref name="m"/> has value and predicate <paramref name="predicate"/> is true, otherwise does nothing
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="m"></param>
/// <param name="fn"></param>
/// <returns></returns>
public static void DoWhenTrue <T>(this Maybe <T> m, Func <T, bool> predicate, Action <T> fn)
{
Contract.Requires(predicate != null);
if (m.IsSomething())
{
if (predicate(m.Value))
{
fn(m.Value);
}
}
}
/// <summary>
/// Calls <paramref name="fn"/> if <paramref name="m"/> has value, otherwise calls <paramref name="else"/>
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="m"></param>
/// <param name="fn"></param>
/// <param name="else"></param>
/// <returns></returns>
public static Maybe <T> Match <T>(this Maybe <T> m, Action <T> fn, Action @else)
{
if (m.IsSomething())
{
fn(m.Value);
}
else
{
@else();
}
return(m);
}
/// <summary>
/// Converts Maybe to corresponding Nullable
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="a"></param>
/// <returns></returns>
public static T?ToNullable <T>(this Maybe <T> a) where T : struct
{
return(a.IsSomething() ? a.Value : new T?());
}
public static bool IsNothing <T>(this Maybe <T> a) => !a.IsSomething();
/// <summary> /// Returns <paramref name="a"/> if its Value exists or returns <paramref name="b"/> /// </summary> /// <typeparam name="T"></typeparam> /// <param name="a"></param> /// <param name="b"></param> /// <returns></returns> public static Maybe <T> Or <T>(this Maybe <T> a, Maybe <T> b) => a.IsSomething() ? a : b;
/// <summary> /// Returns <paramref name="a"/> if its Value exists or returns <paramref name="b"/>() /// </summary> /// <typeparam name="T"></typeparam> /// <param name="a"></param> /// <param name="b"></param> /// <returns></returns> public static Maybe <T> Or <T>(this Maybe <T> a, Func <Maybe <T> > b) => a.IsSomething() ? a : b();
/// <summary> /// Returns <paramref name="a"/> if its Value exists or returns <paramref name="b"/>, wrapped as Maybe /// </summary> /// <typeparam name="T"></typeparam> /// <param name="a"></param> /// <param name="b"></param> /// <returns></returns> public static Maybe <T> Or <T>(this Maybe <T> a, T b) => a.IsSomething() ? a : b.ToMaybe();
/// <summary> /// Converts Maybe to corresponding Nullable /// </summary> /// <typeparam name="T"></typeparam> /// <param name="a"></param> /// <returns></returns> public static T?ToNullable <T>(this Maybe <T> a) where T : struct => a.IsSomething() ? a.Value : (T?)null;
