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Rank.cs
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Rank.cs
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namespace SuperLinq.Async;
public static partial class AsyncSuperEnumerable
{
/// <summary>
/// Ranks each item in the sequence in ascending order using a default comparer.
/// The rank is equal to index + 1 of the first element of the item's equality set.
/// </summary>
/// <typeparam name="TSource">Type of item in the sequence</typeparam>
/// <param name="source">The sequence whose items will be ranked</param>
/// <returns>A sorted sequence of items and their rank.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
public static IAsyncEnumerable<(TSource item, int rank)> Rank<TSource>(
this IAsyncEnumerable<TSource> source)
{
return source.RankBy(Identity);
}
/// <summary>
/// Ranks each item in the sequence in ascending order using a caller-supplied comparer.
/// The rank is equal to index + 1 of the first element of the item's equality set.
/// </summary>
/// <typeparam name="TSource">The type of the elements in the source sequence</typeparam>
/// <param name="source">The sequence of items to rank</param>
/// <param name="comparer">A object that defines comparison semantics for the elements in the sequence</param>
/// <returns>A sorted sequence of items and their rank.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
public static IAsyncEnumerable<(TSource item, int rank)> Rank<TSource>(
this IAsyncEnumerable<TSource> source, IComparer<TSource> comparer)
{
return source.RankBy(Identity, comparer);
}
/// <summary>
/// Ranks each item in the sequence in the order defined by <paramref name="sortDirection"/>
/// using a default comparer. The rank is equal to index + 1 of the first element of the item's equality set.
/// </summary>
/// <typeparam name="TSource">Type of item in the sequence</typeparam>
/// <param name="source">The sequence whose items will be ranked</param>
/// <param name="sortDirection">Defines the ordering direction for the sequence</param>
/// <returns>A sorted sequence of items and their rank.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
public static IAsyncEnumerable<(TSource item, int rank)> Rank<TSource>(
this IAsyncEnumerable<TSource> source, OrderByDirection sortDirection)
{
return source.RankBy(Identity, sortDirection);
}
/// <summary>
/// Ranks each item in the sequence in the order defined by <paramref name="sortDirection"/>
/// using a caller-supplied comparer. The rank is equal to index + 1 of the first element of the item's equality set.
/// </summary>
/// <typeparam name="TSource">The type of the elements in the source sequence</typeparam>
/// <param name="source">The sequence of items to rank</param>
/// <param name="comparer">A object that defines comparison semantics for the elements in the sequence</param>
/// <param name="sortDirection">Defines the ordering direction for the sequence</param>
/// <returns>A sorted sequence of items and their rank.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
public static IAsyncEnumerable<(TSource item, int rank)> Rank<TSource>(
this IAsyncEnumerable<TSource> source,
IComparer<TSource> comparer,
OrderByDirection sortDirection)
{
return source.RankBy(Identity, comparer, sortDirection);
}
private static async IAsyncEnumerable<(TSource, int)> RankCore<TSource, TKey>(
IAsyncEnumerable<TSource> source,
Func<TSource, TKey> keySelector,
IComparer<TKey>? comparer,
bool isDense,
OrderByDirection sortDirection = OrderByDirection.Ascending,
[EnumeratorCancellation] CancellationToken cancellationToken = default)
{
comparer ??= Comparer<TKey>.Default;
var rank = 0;
var count = 1;
await foreach (var (cur, lag) in source
.OrderBy(keySelector, comparer, sortDirection)
.Lag(1)
.WithCancellation(cancellationToken)
.ConfigureAwait(false))
{
#pragma warning disable CA1508 // Avoid dead conditional code
if (rank == 0
|| comparer.Compare(
keySelector(cur),
keySelector(Debug.AssertNotNull(lag))) != 0)
{
rank += isDense ? 1 : count;
count = 0;
}
#pragma warning restore CA1508 // Avoid dead conditional code
count++;
yield return (cur, rank);
}
}
}