Class Sequence

Various methods to work with classes implementing IEnumerable<T> interface.

Inheritance

Object

Sequence

Inherited Members

Object.Equals(Object)

Object.Equals(Object, Object)

Object.GetHashCode()

Object.GetType()

Object.MemberwiseClone()

Object.ReferenceEquals(Object, Object)

Object.ToString()

Namespace: DotNext.Collections.Generic

Assembly: DotNext.dll

Syntax

public static class Sequence

Methods

Append<T>(IEnumerable<T>, T[])

Adds items to the end of collection.

Declaration

public static IEnumerable<T> Append<T>(this IEnumerable<T> collection, params T[] items)

Parameters

Type	Name	Description
IEnumerable<T>	collection	The collection to be concatenated with the items.
T[]	items	The items to be added to the end of the collection.

Returns

Type	Description
IEnumerable<T>	The concatenated collection.

Type Parameters

Name	Description
T	The type of items in the collection.

ElementAt<T>(IEnumerable<T>, Int32, out T)

Obtains element at the specified index in the sequence.

Declaration

public static bool ElementAt<T>(this IEnumerable<T> collection, int index, out T element)

Parameters

Type	Name	Description
IEnumerable<T>	collection	Source collection.
Int32	index	Index of the element to read.
T	element	Obtained element.

Returns

Type	Description
Boolean	true, if element is available in the collection and obtained successfully; otherwise, false.

Type Parameters

Name	Description
T	Type of elements in the sequence.

Remarks

This method is optimized for types IList<T> and IReadOnlyList<T>.

ElementAtAsync<T>(IAsyncEnumerable<T>, Int32, CancellationToken)

Obtains element at the specified index in the sequence.

Declaration

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

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection	Source collection.
Int32	index	Index of the element to read.
CancellationToken	token	The token that can be used to cancel enumeration.

Returns

Type	Description
ValueTask<Optional<T>>	The requested element; or None if index is out of range.

Type Parameters

Name	Description
T	Type of elements in the sequence.

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

FirstOrEmpty<T>(IEnumerable<T>)

Obtains first value in the sequence; or None if sequence is empty.

Declaration

public static Optional<T> FirstOrEmpty<T>(this IEnumerable<T> seq)

Parameters

Type	Name	Description
IEnumerable<T>	seq	A sequence to check. Cannot be null.

Returns

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

Type Parameters

Name	Description
T	Type of elements in the sequence.

FirstOrEmpty<T>(IEnumerable<T>, ValueFunc<T, Boolean>)

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

Declaration

public static Optional<T> FirstOrEmpty<T>(this IEnumerable<T> seq, in ValueFunc<T, bool> filter)

Parameters

Type	Name	Description
IEnumerable<T>	seq	A collection to return an element from.
ValueFunc<T, Boolean>	filter	A function to test each element for a condition.

Returns

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

Type Parameters

Name	Description
T	The type of the elements of source.

FirstOrEmpty<T>(IEnumerable<T>, Predicate<T>)

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

Declaration

public static Optional<T> FirstOrEmpty<T>(this IEnumerable<T> seq, Predicate<T> filter)

Parameters

Type	Name	Description
IEnumerable<T>	seq	A collection to return an element from.
Predicate<T>	filter	A function to test each element for a condition.

Returns

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

Type Parameters

Name	Description
T	The type of the elements of source.

FirstOrEmptyAsync<T>(IAsyncEnumerable<T>, ValueFunc<T, Boolean>, CancellationToken)

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

Declaration

public static ValueTask<Optional<T>> FirstOrEmptyAsync<T>(this IAsyncEnumerable<T> seq, ValueFunc<T, bool> filter, CancellationToken token = default(CancellationToken))

Parameters

Type	Name	Description
IAsyncEnumerable<T>	seq	A collection to return an element from.
ValueFunc<T, Boolean>	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	The type of the elements of source.

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

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

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

Declaration

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

Parameters

Type	Name	Description
IAsyncEnumerable<T>	seq	A collection to return an element from.
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	The type of the elements of source.

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

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

Obtains first value in the sequence; or None if sequence is empty.

Declaration

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

Parameters

Type	Name	Description
IAsyncEnumerable<T>	seq	A sequence to check. Cannot be null.
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	Type of elements in the sequence.

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

FirstOrNull<T>(IEnumerable<T>)

Obtains first value type in the sequence; or null if sequence is empty.

Declaration

public static T? FirstOrNull<T>(this IEnumerable<T> seq)

    where T : struct

Parameters

Type	Name	Description
IEnumerable<T>	seq	A sequence to check. Cannot be null.

Returns

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

Type Parameters

Name	Description
T	Type of elements in the sequence.

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

Obtains first value type in the sequence; or null if sequence is empty.

Declaration

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

    where T : struct

Parameters

Type	Name	Description
IAsyncEnumerable<T>	seq	A sequence to check. Cannot be null.
CancellationToken	token	The token that can be used to cancel enumeration.

Returns

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

Type Parameters

Name	Description
T	Type of elements in the sequence.

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

ForEach<T>(IEnumerable<T>, ValueAction<T>)

Applies specified action to each collection element.

Declaration

public static void ForEach<T>(this IEnumerable<T> collection, in ValueAction<T> action)

Parameters

Type	Name	Description
IEnumerable<T>	collection	A collection to enumerate. Cannot be null.
ValueAction<T>	action	An action to applied for each element.

Type Parameters

Name	Description
T	Type of elements in the collection.

ForEach<T>(IEnumerable<T>, Action<T>)

Applies specified action to each collection element.

Declaration

public static void ForEach<T>(this IEnumerable<T> collection, Action<T> action)

Parameters

Type	Name	Description
IEnumerable<T>	collection	A collection to enumerate. Cannot be null.
Action<T>	action	An action to applied for each element.

Type Parameters

Name	Description
T	Type of elements in the collection.

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

Applies specified action to each collection element asynchronously.

Declaration

public static ValueTask ForEachAsync<T>(this IAsyncEnumerable<T> collection, ValueAction<T> action, CancellationToken token = default(CancellationToken))

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection	A collection to enumerate. Cannot be null.
ValueAction<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	Type of elements in the collection.

Exceptions

Type	Condition
OperationCanceledException	The enumeration has been canceled.

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

Applies specified action to each collection element asynchronously.

Declaration

public static ValueTask ForEachAsync<T>(this IAsyncEnumerable<T> collection, ValueFunc<T, CancellationToken, ValueTask> action, CancellationToken token = default(CancellationToken))

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection	A collection to enumerate. Cannot be null.
ValueFunc<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	Type of elements in the collection.

Exceptions

Type	Condition
OperationCanceledException	The enumeration has been canceled.

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

Applies specified action to each collection element asynchronously.

Declaration

public static ValueTask ForEachAsync<T>(this IAsyncEnumerable<T> collection, Action<T> action, CancellationToken token = default(CancellationToken))

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection	A collection to enumerate. Cannot be null.
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	Type of elements in the collection.

Exceptions

Type	Condition
OperationCanceledException	The enumeration has been canceled.

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

Applies specified action to each collection element asynchronously.

Declaration

public static ValueTask ForEachAsync<T>(this IAsyncEnumerable<T> collection, Func<T, CancellationToken, ValueTask> action, CancellationToken token = default(CancellationToken))

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection	A collection to enumerate. Cannot be null.
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	Type of elements in the collection.

Exceptions

Type	Condition
OperationCanceledException	The enumeration has been canceled.

ForEachAsync<T>(IEnumerable<T>, ValueFunc<T, CancellationToken, ValueTask>, CancellationToken)

Applies the specified asynchronous action to each collection element.

Declaration

public static ValueTask ForEachAsync<T>(this IEnumerable<T> collection, ValueFunc<T, CancellationToken, ValueTask> action, CancellationToken token = default(CancellationToken))

Parameters

Type	Name	Description
IEnumerable<T>	collection	A collection to enumerate. Cannot be null.
ValueFunc<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	Type of elements in the collection.

Exceptions

Type	Condition
OperationCanceledException	The enumeration has been canceled.

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

Applies the specified asynchronous action to each collection element.

Declaration

public static ValueTask ForEachAsync<T>(this IEnumerable<T> collection, Func<T, CancellationToken, ValueTask> action, CancellationToken token = default(CancellationToken))

Parameters

Type	Name	Description
IEnumerable<T>	collection	A collection to enumerate. Cannot be null.
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	Type of elements in the collection.

Exceptions

Type	Condition
OperationCanceledException	The enumeration has been canceled.

GetAsyncEnumerator<T>(IEnumerable<T>, CancellationToken)

Obtains asynchronous enumerator over the sequence of elements.

Declaration

public static IAsyncEnumerator<T> GetAsyncEnumerator<T>(this IEnumerable<T> enumerable, CancellationToken token = default(CancellationToken))

Parameters

Type	Name	Description
IEnumerable<T>	enumerable	The collection of elements.
CancellationToken	token	The token that can be used by consumer to cancel the enumeration.

Returns

Type	Description
IAsyncEnumerator<T>	The asynchronous wrapper over synchronous enumerator.

Type Parameters

Name	Description
T	The type of the elements in the collection.

GetConsumer<T>(IProducerConsumerCollection<T>)

Gets consumer of thread-safe concurrent collection.

Declaration

public static Sequence.ConsumingEnumerable<T> GetConsumer<T>(this IProducerConsumerCollection<T> collection)

Parameters

Type	Name	Description
IProducerConsumerCollection<T>	collection	The concurrent collection.

Returns

Type	Description
Sequence.ConsumingEnumerable<T>	The consumer in the form of enumerable collection.

Type Parameters

Name	Description
T	The type of elements in the collection.

Limit<T>(IEnumerator<T>, Int32, Boolean)

Limits the number of the elements in the sequence.

Declaration

public static Sequence.LimitedEnumerator<T> Limit<T>(this IEnumerator<T> enumerator, int count, bool leaveOpen = false)

Parameters

Type	Name	Description
IEnumerator<T>	enumerator	The sequence of the elements.
Int32	count	The maximum number of the elements in the returned sequence.
Boolean	leaveOpen	false to dispose enumerator; otherwise, true.

Returns

Type	Description
Sequence.LimitedEnumerator<T>	The enumerator which is limited by count.

Type Parameters

Name	Description
T	The type of items in the sequence.

Prepend<T>(IEnumerable<T>, T[])

Adds items to the beginning of collection.

Declaration

public static IEnumerable<T> Prepend<T>(this IEnumerable<T> collection, params T[] items)

Parameters

Type	Name	Description
IEnumerable<T>	collection	The collection to be concatenated with the items.
T[]	items	The items to be added to the beginning of the collection.

Returns

Type	Description
IEnumerable<T>	The concatenated collection.

Type Parameters

Name	Description
T	The type of items in the collection.

SequenceHashCode(IEnumerable<Object>, Boolean)

Computes hash code for the sequence of objects.

Declaration

public static int SequenceHashCode(this IEnumerable<object> sequence, bool salted = true)

Parameters

Type	Name	Description
IEnumerable<Object>	sequence	The sequence of elements.
Boolean	salted	true to include randomized salt data into hashing; false to use data from memory only.

Returns

Type	Description
Int32	The hash code computed from each element in the sequence.

Singleton<T>(T)

Constructs a sequence from the single element.

Declaration

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

Parameters

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

Returns

Type	Description
IEnumerable<T>	Sequence of single element.

Type Parameters

Name	Description
T	Type of element.

Skip<T>(IEnumerator<T>, Int32)

Bypasses a specified number of elements in a sequence.

Declaration

public static bool Skip<T>(this IEnumerator<T> enumerator, int count)

Parameters

Type	Name	Description
IEnumerator<T>	enumerator	Enumerator to modify. Cannot be null.
Int32	count	The number of elements to skip.

Returns

Type	Description
Boolean	true, if current element is available; otherwise, false.

Type Parameters

Name	Description
T	The type of the elements in the sequence.

Skip<TEnumerator, T>(ref TEnumerator, Int32)

Bypasses a specified number of elements in a sequence.

Declaration

public static bool Skip<TEnumerator, T>(this ref TEnumerator enumerator, int count)

    where TEnumerator : struct, IEnumerator<T>

Parameters

Type	Name	Description
TEnumerator	enumerator	Enumerator to modify.
Int32	count	The number of elements to skip.

Returns

Type	Description
Boolean	true, if current element is available; otherwise, false.

Type Parameters

Name	Description
TEnumerator	The type of the sequence.
T	The type of the elements in the sequence.

SkipAsync<T>(IAsyncEnumerator<T>, Int32)

Bypasses a specified number of elements in a sequence.

Declaration

public static ValueTask<bool> SkipAsync<T>(this IAsyncEnumerator<T> enumerator, int count)

Parameters

Type	Name	Description
IAsyncEnumerator<T>	enumerator	Enumerator to modify. Cannot be null.
Int32	count	The number of elements to skip.

Returns

Type	Description
ValueTask<Boolean>	true, if current element is available; otherwise, false.

Type Parameters

Name	Description
T	The type of the elements in the sequence.

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

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.

SkipNulls<T>(IEnumerable<T>)

Skip null values in the collection.

Declaration

public static IEnumerable<T> SkipNulls<T>(this IEnumerable<T> collection)

    where T : class

Parameters

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

Returns

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

Type Parameters

Name	Description
T	Type of elements in the collection.

ToArrayAsync<T>(IAsyncEnumerable<T>, Int32, MemoryAllocator<T>, CancellationToken)

Converts asynchronous collection to the array.

Declaration

public static Task<T[]> ToArrayAsync<T>(this IAsyncEnumerable<T> collection, int initialCapacity = 10, MemoryAllocator<T> allocator = null, CancellationToken token = default(CancellationToken))

Parameters

Type	Name	Description
IAsyncEnumerable<T>	collection	The asynchronous collection.
Int32	initialCapacity	The initial capacity of internal buffer.
MemoryAllocator<T>	allocator	The memory allocator used by internal buffer.
CancellationToken	token	The token that can be used to cancel the operation.

Returns

Type	Description
Task<T[]>	The array representing all elements from the source collection.

Type Parameters

Name	Description
T	Type of elements in the collection.

Exceptions

Type	Condition
OperationCanceledException	The operation has been canceled.

ToAsyncEnumerable<T>(IEnumerable<T>)

Converts synchronous collection of elements to asynchronous.

Declaration

public static IAsyncEnumerable<T> ToAsyncEnumerable<T>(this IEnumerable<T> enumerable)

Parameters

Type	Name	Description
IEnumerable<T>	enumerable	The collection of elements.

Returns

Type	Description
IAsyncEnumerable<T>	The asynchronous wrapper over synchronous collection of elements.

Type Parameters

Name	Description
T	The type of the elements in the collection.

ToAsyncEnumerable<T>(Func<CancellationToken, ValueTask<Optional<T>>>)

Converts generator function to enumerable collection.

Declaration

public static Sequence.AsyncGenerator<T> ToAsyncEnumerable<T>(this Func<CancellationToken, ValueTask<Optional<T>>> generator)

Parameters

Type	Name	Description
Func<CancellationToken, ValueTask<Optional<T>>>	generator	Stateful generator function.

Returns

Type	Description
Sequence.AsyncGenerator<T>	The enumerable collection.

Type Parameters

Name	Description
T	The type of the elements in the collection.

Exceptions

Type	Condition
ArgumentNullException	generator is null.

ToEnumerable<T>(Func<Optional<T>>)

Converts generator function to enumerable collection.

Declaration

public static Sequence.Generator<T> ToEnumerable<T>(this Func<Optional<T>> generator)

Parameters

Type	Name	Description
Func<Optional<T>>	generator	Stateful generator function.

Returns

Type	Description
Sequence.Generator<T>	The enumerable collection.

Type Parameters

Name	Description
T	The type of the elements in the collection.

Exceptions

Type	Condition
ArgumentNullException	generator is null.

ToEnumerator<T>(ReadOnlyMemory<T>)

Gets enumerator over all elements in the memory.

Declaration

public static IEnumerator<T> ToEnumerator<T>(ReadOnlyMemory<T> memory)

Parameters

Type	Name	Description
ReadOnlyMemory<T>	memory	The memory block to be converted.

Returns

Type	Description
IEnumerator<T>	The enumerator over all elements in the memory.

Type Parameters

Name	Description
T	The type of elements in the memory.

See Also

ToEnumerable<T>(ReadOnlyMemory<T>)

ToString<T>(IEnumerable<T>, String, String)

Concatenates each element from the collection into single string.

Declaration

public static string ToString<T>(this IEnumerable<T> collection, string delimiter, string ifEmpty = "")

Parameters

Type	Name	Description
IEnumerable<T>	collection	Collection to convert. Cannot be null.
String	delimiter	Delimiter between elements in the final string.
String	ifEmpty	A string to be returned if collection has no elements.

Returns

Type	Description
String	Converted collection into string.

Type Parameters

Name	Description
T	Type of array elements.