Class AsyncEnumerable

Provides extension methods for IAsyncEnumerable<T> interface.

Inheritance

object

AsyncEnumerable

Inherited Members

object.GetType()

object.MemberwiseClone()

object.ToString()

object.Equals(object)

object.Equals(object, object)

object.ReferenceEquals(object, object)

object.GetHashCode()

Namespace: DotNext.Collections.Generic

Assembly: DotNext.dll

Syntax

public static class AsyncEnumerable

Methods

CopyAsync<T>(IAsyncEnumerable<T>, int, MemoryAllocator<T>?, CancellationToken)

Creates a copy of the elements from the collection.

Declaration

public static Task<MemoryOwner<T>> CopyAsync<T>(this IAsyncEnumerable<T> enumerable, int sizeHint = 0, MemoryAllocator<T>? allocator = null, CancellationToken token = default)

Parameters

Type	Name	Description
IAsyncEnumerable<T>	enumerable	The collection to copy.
int	sizeHint	The approximate size of the collection, if known.
MemoryAllocator<T>	allocator	The allocator of the memory block used to place copied elements.
CancellationToken	token	The token that can be used to cancel the enumeration.

Returns

Type	Description
Task<MemoryOwner<T>>	Rented memory block containing a copy of the elements from the collection.

Type Parameters

Name	Description
T	The type of elements in the collection.

Exceptions

Type	Condition
ArgumentNullException	enumerable is null.
ArgumentOutOfRangeException	sizeHint is less than zero.
OperationCanceledException	The operation has been canceled.

FirstOrNoneAsync<T>(IAsyncEnumerable<T>, Predicate<T>, CancellationToken)

Returns the first element in a sequence that satisfies a specified condition.

Declaration

public static ValueTask<Optional<T>> FirstOrNoneAsync<T>(this IAsyncEnumerable<T> collection, Predicate<T> filter, CancellationToken token = default)

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection
Predicate<T>	filter	A function to test each element for a condition.
CancellationToken	token	The token that can be used to cancel enumeration.

Returns

Type	Description
ValueTask<Optional<T>>	The first element in the sequence that matches to the specified filter; or empty value.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

FirstOrNoneAsync<T>(IAsyncEnumerable<T>, CancellationToken)

Obtains the first element of a sequence; or None if the sequence is empty.

Declaration

public static ValueTask<Optional<T>> FirstOrNoneAsync<T>(this IAsyncEnumerable<T> collection, CancellationToken token = default)

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection
CancellationToken	token	The token that can be used to cancel enumeration.

Returns

Type	Description
ValueTask<Optional<T>>	The first element in the sequence; or None if sequence is empty.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

FirstOrNullAsync<T>(IAsyncEnumerable<T>, CancellationToken)

Obtains the first value of a sequence; or null if the sequence is empty.

Declaration

public static ValueTask<T?> FirstOrNullAsync<T>(this IAsyncEnumerable<T> seq, CancellationToken token = default) where T : struct

Parameters

Type	Name	Description
IAsyncEnumerable<T>	seq
CancellationToken	token	The token that can be used to cancel enumeration.

Returns

Type	Description
ValueTask<T?>	First element in the sequence; or null if sequence is empty.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

ForEachAsync<T>(IAsyncEnumerable<T>, Action<T>, CancellationToken)

Applies specified action to each element of the collection asynchronously.

Declaration

public static ValueTask ForEachAsync<T>(this IAsyncEnumerable<T> collection, Action<T> action, CancellationToken token = default) where T : allows ref struct

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection
Action<T>	action	An action to applied for each element.
CancellationToken	token	The token that can be used to cancel the enumeration.

Returns

Type	Description
ValueTask	The task representing asynchronous execution of this method.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
OperationCanceledException	The enumeration has been canceled.

ForEachAsync<T>(IAsyncEnumerable<T>, Func<T, CancellationToken, ValueTask>, CancellationToken)

Applies the specified action to each element of the collection asynchronously.

Declaration

public static ValueTask ForEachAsync<T>(this IAsyncEnumerable<T> collection, Func<T, CancellationToken, ValueTask> action, CancellationToken token = default) where T : allows ref struct

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection
Func<T, CancellationToken, ValueTask>	action	An action to applied for each element.
CancellationToken	token	The token that can be used to cancel the enumeration.

Returns

Type	Description
ValueTask	The task representing asynchronous execution of this method.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
OperationCanceledException	The enumeration has been canceled.

LastOrNoneAsync<T>(IAsyncEnumerable<T>, CancellationToken)

Obtains the last element of a sequence; or None if the sequence is empty.

Declaration

public static ValueTask<Optional<T>> LastOrNoneAsync<T>(this IAsyncEnumerable<T> collection, CancellationToken token = default)

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection
CancellationToken	token	The token that can be used to cancel enumeration.

Returns

Type	Description
ValueTask<Optional<T>>	The last element in the sequence; or None if sequence is empty.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

LastOrNullAsync<T>(IAsyncEnumerable<T>, CancellationToken)

Obtains the last value of a sequence; or null if the sequence is empty.

Declaration

public static ValueTask<T?> LastOrNullAsync<T>(this IAsyncEnumerable<T> seq, CancellationToken token = default) where T : struct

Parameters

Type	Name	Description
IAsyncEnumerable<T>	seq
CancellationToken	token	The token that can be used to cancel enumeration.

Returns

Type	Description
ValueTask<T?>	The last element in the sequence; or null if sequence is empty.

Type Parameters

Name	Description
T

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

Singleton<T>(T)

Constructs read-only sequence with a single item in it.

Declaration

public static IAsyncEnumerable<T> Singleton<T>(T item)

Parameters

Type	Name	Description
T	item	An item to be placed into list.

Returns

Type	Description
IAsyncEnumerable<T>	Read-only list containing single item.

Type Parameters

Name	Description
T

SkipNulls<T>(IAsyncEnumerable<T?>)

Skip null values in the collection.

Declaration

public static IAsyncEnumerable<T> SkipNulls<T>(this IAsyncEnumerable<T?> collection) where T : class

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection	A collection to check. Cannot be null.

Returns

Type	Description
IAsyncEnumerable<T>	Modified lazy collection without null values.

Type Parameters

Name	Description
T	Type of elements in the collection.

Throw<T>(Exception)

Gets an asynchronous collection that throws the specified exception.

Declaration

public static IAsyncEnumerable<T> Throw<T>(Exception e) where T : notnull, allows ref struct

Parameters

Type	Name	Description
Exception	e	The exception to be thrown by the enumerator.

Returns

Type	Description
IAsyncEnumerable<T>	Empty asynchronous collection which enumerator throws e.

Type Parameters

Name	Description
T