Method Publish

Publish<TSource>(IEnumerable<TSource>)

Creates a buffer with a view over the source sequence, causing each enumerator to obtain access to the remainder of the sequence from the current index in the buffer.

Declaration

public static IBuffer<TSource> Publish<TSource>(this IEnumerable<TSource> source)

Parameters

Type	Name	Description
IEnumerable<TSource>	source	Source sequence.

Returns

Type	Description
IBuffer<TSource>	Buffer enabling each enumerator to retrieve elements from the shared source sequence, starting from the index at the point of obtaining the enumerator.

Type Parameters

Name	Description
TSource	Source sequence element type.

Remarks

A separate buffer will be maintained for each IEnumerator<T> created from the returned IEnumerable<T>. This buffer will be maintained until the enumerator is disposed, and will contain all elements returned by source from the time that the IEnumerator<T> is created.

This operator uses deferred execution and streams its result.

Examples

The following code example demonstrates how to publish multiple views of the same enumerator using Publish.

var sequence = Enumerable.Range(0, 10);

// allow multiple consumers to cache views of the same sequence
using var rng = sequence.Publish();
using var e1 = rng.GetEnumerator();    // e1 has a view on the source starting from element 0

Debug.Assert(e1.MoveNext());
Console.WriteLine("e1.MoveNext()");
Console.WriteLine($"e1.Current: {e1.Current}");

Debug.Assert(e1.MoveNext());
Console.WriteLine("e1.MoveNext()");
Console.WriteLine($"e1.Current: {e1.Current}");

using var e2 = rng.GetEnumerator();

Debug.Assert(e2.MoveNext());    // e2 has a view on the source starting from element 2
Console.WriteLine("e2.MoveNext()");
Console.WriteLine($"e1.Current: {e1.Current}");
Console.WriteLine($"e2.Current: {e2.Current}");

Debug.Assert(e1.MoveNext());    // e1 continues to enumerate over its view
Console.WriteLine("e1.MoveNext()");
Console.WriteLine($"e1.Current: {e1.Current}");
Console.WriteLine($"e2.Current: {e2.Current}");

// This code produces the following output:
// e1.MoveNext()
// e1.Current: 0
// e1.MoveNext()
// e1.Current: 1
// e2.MoveNext()
// e1.Current: 1
// e2.Current: 2
// e1.MoveNext()
// e1.Current: 2
// e2.Current: 2

Exceptions

Type	Condition
ArgumentNullException	source is null.