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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
namespace System.Linq
{
public static partial class AsyncEnumerable
{
/// <summary>Computes the average of a sequence of values.</summary>
/// <param name="source">A sequence of values to calculate the average of.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
/// <returns>The average of the sequence of values.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="OverflowException">The sum of the elements in the sequence is larger than <see cref="long.MaxValue"/> (via the returned task).</exception>
/// <exception cref="InvalidOperationException"><paramref name="source"/> contains no elements (via the returned task).</exception>
public static ValueTask<double> AverageAsync(
this IAsyncEnumerable<int> source,
CancellationToken cancellationToken = default)
{
ThrowHelper.ThrowIfNull(source);
return Impl(source.WithCancellation(cancellationToken).ConfigureAwait(false));
static async ValueTask<double> Impl(
ConfiguredCancelableAsyncEnumerable<int> source)
{
long sum = 0;
long count = 0;
await foreach (int item in source)
{
checked { sum += item; }
count++;
}
if (count == 0)
{
ThrowHelper.ThrowNoElementsException();
}
return (double)sum / count;
}
}
/// <summary>Computes the average of a sequence of values.</summary>
/// <param name="source">A sequence of values to calculate the average of.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
/// <returns>The average of the sequence of values.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="OverflowException">The sum of the elements in the sequence is larger than <see cref="long.MaxValue"/> (via the returned task).</exception>
/// <exception cref="InvalidOperationException"><paramref name="source"/> contains no elements (via the returned task).</exception>
public static ValueTask<double> AverageAsync(
this IAsyncEnumerable<long> source,
CancellationToken cancellationToken = default)
{
ThrowHelper.ThrowIfNull(source);
return Impl(source.WithCancellation(cancellationToken).ConfigureAwait(false));
static async ValueTask<double> Impl(
ConfiguredCancelableAsyncEnumerable<long> source)
{
long sum = 0;
long count = 0;
await foreach (long item in source)
{
checked { sum += item; }
count++;
}
if (count == 0)
{
ThrowHelper.ThrowNoElementsException();
}
return (double)sum / count;
}
}
/// <summary>Computes the average of a sequence of values.</summary>
/// <param name="source">A sequence of values to calculate the average of.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
/// <returns>The average of the sequence of values.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="InvalidOperationException"><paramref name="source"/> contains no elements (via the returned task).</exception>
public static ValueTask<float> AverageAsync(
this IAsyncEnumerable<float> source, CancellationToken cancellationToken = default)
{
ThrowHelper.ThrowIfNull(source);
return Impl(source.WithCancellation(cancellationToken).ConfigureAwait(false));
static async ValueTask<float> Impl(
ConfiguredCancelableAsyncEnumerable<float> source)
{
double sum = 0;
long count = 0;
await foreach (double item in source)
{
sum += item;
count++;
}
if (count == 0)
{
ThrowHelper.ThrowNoElementsException();
}
return (float)(sum / count);
}
}
/// <summary>Computes the average of a sequence of values.</summary>
/// <param name="source">A sequence of values to calculate the average of.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
/// <returns>The average of the sequence of values.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="InvalidOperationException"><paramref name="source"/> contains no elements (via the returned task).</exception>
public static ValueTask<double> AverageAsync(
this IAsyncEnumerable<double> source, CancellationToken cancellationToken = default)
{
ThrowHelper.ThrowIfNull(source);
return Impl(source.WithCancellation(cancellationToken).ConfigureAwait(false));
static async ValueTask<double> Impl(
ConfiguredCancelableAsyncEnumerable<double> source)
{
double sum = 0;
long count = 0;
await foreach (double item in source)
{
sum += item;
count++;
}
if (count == 0)
{
ThrowHelper.ThrowNoElementsException();
}
return (double)sum / count;
}
}
/// <summary>Computes the average of a sequence of values.</summary>
/// <param name="source">A sequence of values to calculate the average of.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
/// <returns>The average of the sequence of values.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="InvalidOperationException"><paramref name="source"/> contains no elements (via the returned task).</exception>
public static ValueTask<decimal> AverageAsync(
this IAsyncEnumerable<decimal> source, CancellationToken cancellationToken = default)
{
ThrowHelper.ThrowIfNull(source);
return Impl(source.WithCancellation(cancellationToken).ConfigureAwait(false));
static async ValueTask<decimal> Impl(
ConfiguredCancelableAsyncEnumerable<decimal> source)
{
decimal sum = 0;
long count = 0;
await foreach (decimal item in source)
{
sum += item;
count++;
}
if (count == 0)
{
ThrowHelper.ThrowNoElementsException();
}
return sum / count;
}
}
/// <summary>Computes the average of a sequence of nullable values.</summary>
/// <param name="source">A sequence of nullable values to calculate the average of.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
/// <returns>The average of the sequence of values, or null if the source sequence is empty or contains only values that are null.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="OverflowException">The sum of the elements in the sequence is larger than <see cref="long.MaxValue"/> (via the returned task).</exception>
/// <exception cref="InvalidOperationException"><paramref name="source"/> contains no elements (via the returned task).</exception>
public static ValueTask<double?> AverageAsync(
this IAsyncEnumerable<int?> source, CancellationToken cancellationToken = default)
{
ThrowHelper.ThrowIfNull(source);
return Impl(source.WithCancellation(cancellationToken).ConfigureAwait(false));
static async ValueTask<double?> Impl(
ConfiguredCancelableAsyncEnumerable<int?> source)
{
long sum = 0;
long count = 0;
await foreach (int? item in source)
{
if (item is int value)
{
checked { sum += value; }
count++;
}
}
return count != 0 ? (double)sum / count : null;
}
}
/// <summary>Computes the average of a sequence of nullable values.</summary>
/// <param name="source">A sequence of nullable values to calculate the average of.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
/// <returns>The average of the sequence of values, or null if the source sequence is empty or contains only values that are null.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="OverflowException">The sum of the elements in the sequence is larger than <see cref="long.MaxValue"/> (via the returned task).</exception>
/// <exception cref="InvalidOperationException"><paramref name="source"/> contains no elements (via the returned task).</exception>
public static ValueTask<double?> AverageAsync(
this IAsyncEnumerable<long?> source, CancellationToken cancellationToken = default)
{
ThrowHelper.ThrowIfNull(source);
return Impl(source.WithCancellation(cancellationToken).ConfigureAwait(false));
static async ValueTask<double?> Impl(
ConfiguredCancelableAsyncEnumerable<long?> source)
{
long sum = 0;
long count = 0;
await foreach (long? item in source)
{
if (item is long value)
{
checked { sum += value; }
count++;
}
}
return count != 0 ? (double)sum / count : null;
}
}
/// <summary>Computes the average of a sequence of nullable values.</summary>
/// <param name="source">A sequence of nullable values to calculate the average of.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
/// <returns>The average of the sequence of values, or null if the source sequence is empty or contains only values that are null.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="InvalidOperationException"><paramref name="source"/> contains no elements (via the returned task).</exception>
public static ValueTask<float?> AverageAsync(
this IAsyncEnumerable<float?> source, CancellationToken cancellationToken = default)
{
ThrowHelper.ThrowIfNull(source);
return Impl(source.WithCancellation(cancellationToken).ConfigureAwait(false));
static async ValueTask<float?> Impl(
ConfiguredCancelableAsyncEnumerable<float?> source)
{
double sum = 0;
long count = 0;
await foreach (float? item in source)
{
if (item is float value)
{
sum += value;
count++;
}
}
return count != 0 ? (float)(sum / count) : null;
}
}
/// <summary>Computes the average of a sequence of nullable values.</summary>
/// <param name="source">A sequence of nullable values to calculate the average of.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
/// <returns>The average of the sequence of values, or null if the source sequence is empty or contains only values that are null.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="InvalidOperationException"><paramref name="source"/> contains no elements (via the returned task).</exception>
public static ValueTask<double?> AverageAsync(
this IAsyncEnumerable<double?> source, CancellationToken cancellationToken = default)
{
ThrowHelper.ThrowIfNull(source);
return Impl(source.WithCancellation(cancellationToken).ConfigureAwait(false));
static async ValueTask<double?> Impl(
ConfiguredCancelableAsyncEnumerable<double?> source)
{
double sum = 0;
long count = 0;
await foreach (double? item in source)
{
if (item is double value)
{
sum += value;
count++;
}
}
return count != 0 ? sum / count : null;
}
}
/// <summary>Computes the average of a sequence of nullable values.</summary>
/// <param name="source">A sequence of nullable values to calculate the average of.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
/// <returns>The average of the sequence of values, or null if the source sequence is empty or contains only values that are null.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="InvalidOperationException"><paramref name="source"/> contains no elements (via the returned task).</exception>
public static ValueTask<decimal?> AverageAsync(
this IAsyncEnumerable<decimal?> source, CancellationToken cancellationToken = default)
{
ThrowHelper.ThrowIfNull(source);
return Impl(source.WithCancellation(cancellationToken).ConfigureAwait(false));
static async ValueTask<decimal?> Impl(
ConfiguredCancelableAsyncEnumerable<decimal?> source)
{
decimal sum = 0;
long count = 0;
await foreach (decimal? item in source)
{
if (item is decimal value)
{
sum += value;
count++;
}
}
return count != 0 ? sum / count : null;
}
}
}
}
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