// TODO: TEST
/// <summary>
/// Empties an optional, if a specified predicate
/// is not satisfied.
/// </summary>
/// <param name="predicate">The predicate.</param>
/// <returns>The filtered optional.</returns>
public AsyncOption <T> Filter(Func <T, Task <bool> > predicate)
{
return(InnerTask.FlatMap(option => option
.Match(
some: value => predicate(value).Map(option.Filter),
none: () => Task.FromResult(option)
)).ToAsyncOption());
}
/// <summary>
/// Transforms the inner value in an async optional
/// into another async optional. The result is flattened,
/// and if either is empty, an empty optional is returned.
/// </summary>
/// <param name="mapping">The transformation function.</param>
/// <returns>The transformed optional.</returns>
public AsyncOption <TResult> FlatMap <TResult>(Func <T, Task <Option <TResult> > > mapping)
{
return(InnerTask.FlatMap(option => option
.Match(
some: mapping,
none: () => Task.FromResult(Option.None <TResult>())
)).ToAsyncOption());
}
// TODO: TEST
/// <summary>
/// Determines if the current optional contains a specified value.
/// </summary>
/// <param name="value">The value to locate.</param>
/// <returns>A boolean indicating whether or not the value was found.</returns>
public Task <bool> Contains(Task <T> value)
{
return(InnerTask.FlatMap(option => value.Map(option.Contains)));
}
// TODO: TEST
/// <summary>
/// Empties an optional, if a specified condition
/// is not satisfied.
/// </summary>
/// <param name="condition">The condition.</param>
/// <returns>The filtered optional.</returns>
public AsyncOption <T> Filter(Task <bool> condition)
{
return(InnerTask.FlatMap(option => condition.Map(option.Filter)).ToAsyncOption());
}
// TODO: TEST
/// <summary>
/// Evaluates a specified action, based on whether a value is present or not.
/// </summary>
/// <param name="some">The action to evaluate if the value is present.</param>
/// <param name="none">The action to evaluate if the value is missing.</param>
public Task Match(Func <T, Task> some, Func <Task> none)
{
return(InnerTask.FlatMap(option => option.Match(some, none)));
}
// TODO: TEST
/// <summary>
/// Evaluates a specified function, based on whether a value is present or not.
/// </summary>
/// <param name="some">The function to evaluate if the value is present.</param>
/// <param name="none">The function to evaluate if the value is missing.</param>
/// <returns>The result of the evaluated function.</returns>
public Task <TResult> Match <TResult>(Func <T, Task <TResult> > some, Func <Task <TResult> > none)
{
return(InnerTask.FlatMap(option => option.Match(some, none)));
}
