static async ValueTask <IMemoryOwner <TSource> > ToArrayAsync <TEnumerable, TEnumerator, TSource>(this TEnumerable source, AsyncPredicateAt <TSource> predicate, MemoryPool <TSource> pool, CancellationToken cancellationToken)
where TEnumerable : notnull, IAsyncValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IAsyncEnumerator <TSource>
=> (await ToArrayBuilderAsync <TEnumerable, TEnumerator, TSource>(source, predicate, ArrayPool <TSource> .Shared, cancellationToken).ConfigureAwait(false)).ToArray(pool);
static ValueTask <Option <TSource> > SingleAsync <TEnumerable, TEnumerator, TSource>(this TEnumerable source, AsyncPredicateAt <TSource> predicate, CancellationToken cancellationToken = default)
where TEnumerable : notnull, IAsyncValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IAsyncEnumerator <TSource>
=> GetSingleAsync <TEnumerable, TEnumerator, TSource>(source, predicate, cancellationToken);
static async ValueTask <List <TSource> > ToListAsync <TEnumerable, TEnumerator, TSource>(this TEnumerable source, AsyncPredicateAt <TSource> predicate, CancellationToken cancellationToken)
where TEnumerable : IAsyncValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IAsyncEnumerator <TSource>
{
var enumerator = source.GetAsyncEnumerator(cancellationToken);
await using (enumerator.ConfigureAwait(false))
{
checked
{
var list = new List <TSource>();
for (var index = 0; await enumerator.MoveNextAsync().ConfigureAwait(false); index++)
{
var item = enumerator.Current;
if (await predicate(item, index, cancellationToken).ConfigureAwait(false))
{
list.Add(item);
}
}
return(list);
}
}
}
static async ValueTask <bool> ContainsAsync <TEnumerable, TEnumerator, TSource>(this TEnumerable source, TSource value, IEqualityComparer <TSource>?comparer, AsyncPredicateAt <TSource> predicate, CancellationToken cancellationToken)
where TEnumerable : notnull, IAsyncValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IAsyncEnumerator <TSource>
{
var enumerator = source.GetAsyncEnumerator(cancellationToken);
await using (enumerator.ConfigureAwait(false))
{
if (comparer is null)
{
checked
{
for (var index = 0; await enumerator.MoveNextAsync().ConfigureAwait(false); index++)
{
if (await predicate(enumerator.Current, index, cancellationToken).ConfigureAwait(false) &&
EqualityComparer <TSource> .Default.Equals(enumerator.Current, value))
{
return(true);
}
}
}
}
else
{
checked
{
for (var index = 0; await enumerator.MoveNextAsync().ConfigureAwait(false); index++)
{
if (await predicate(enumerator.Current, index, cancellationToken).ConfigureAwait(false) &&
comparer.Equals(enumerator.Current, value))
{
return(true);
}
}
}
}
}
return(false);
}
static async ValueTask <Option <TSource> > GetSingleAsync <TEnumerable, TEnumerator, TSource>(this TEnumerable source, AsyncPredicateAt <TSource> predicate, CancellationToken cancellationToken)
where TEnumerable : notnull, IAsyncValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IAsyncEnumerator <TSource>
{
var enumerator = source.GetAsyncEnumerator(cancellationToken);
await using (enumerator.ConfigureAwait(false))
{
checked
{
for (var index = 0; await enumerator.MoveNextAsync().ConfigureAwait(false); index++)
{
if (await predicate(enumerator.Current, index, cancellationToken).ConfigureAwait(false))
{
var value = enumerator.Current;
// found first, keep going until end or find second
for (index++; await enumerator.MoveNextAsync().ConfigureAwait(false); index++)
{
if (await predicate(enumerator.Current, index, cancellationToken).ConfigureAwait(false))
{
return(Option.None);
}
}
return(Option.Some(value));
}
}
}
return(Option.None);
}
}
public async ValueTask AddRangeAsync <TEnumerable, TEnumerator>(TEnumerable items, AsyncPredicateAt <T> predicate, CancellationToken cancellationToken)
where TEnumerable : IAsyncValueEnumerable <T, TEnumerator>
where TEnumerator : struct, IAsyncEnumerator <T>
{
Debug.Assert(items is object);
var enumerator = items.GetAsyncEnumerator();
await using (enumerator.ConfigureAwait(false))
{
var destination = _current;
var index = _index;
// Continuously read in items from the enumerator, updating _count
// and _index when we run out of space.
while (await enumerator.MoveNextAsync().ConfigureAwait(false))
{
cancellationToken.ThrowIfCancellationRequested();
var item = enumerator.Current;
if (await predicate(item, index, cancellationToken).ConfigureAwait(false))
{
if ((uint)index >= (uint)destination.Length)
{
AddWithBufferAllocation(item, ref destination, ref index);
}
else
{
destination[index] = item;
}
index++;
}
}
// Final update to _count and _index.
_count += index - _index;
_index = index;
}
}
static async ValueTask <TSource[]> ToArrayAsync <TEnumerable, TEnumerator, TSource>(this TEnumerable source, AsyncPredicateAt <TSource> predicate, CancellationToken cancellationToken)
where TEnumerable : IAsyncValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IAsyncEnumerator <TSource>
{
var builder = new LargeArrayBuilder <TSource>(initialize: true);
await builder.AddRangeAsync <TEnumerable, TEnumerator>(source, predicate, cancellationToken).ConfigureAwait(false);
return(builder.ToArray());
}
static async ValueTask <int> CountAsync <TEnumerable, TEnumerator, TSource>(this TEnumerable source, AsyncPredicateAt <TSource> predicate, CancellationToken cancellationToken)
where TEnumerable : notnull, IAsyncValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IAsyncEnumerator <TSource>
{
var count = 0;
var enumerator = source.GetAsyncEnumerator(cancellationToken);
await using (enumerator.ConfigureAwait(false))
{
checked
{
for (var index = 0; await enumerator.MoveNextAsync().ConfigureAwait(false); index++)
{
var result = await predicate(enumerator.Current, index, cancellationToken).ConfigureAwait(false);
count += Unsafe.As <bool, byte>(ref result);
}
}
}
return(count);
}
public static WhereIndexEnumerable <TEnumerable, TEnumerator, TSource> Where <TEnumerable, TEnumerator, TSource>(this TEnumerable source, AsyncPredicateAt <TSource> predicate)
where TEnumerable : notnull, IAsyncValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IAsyncEnumerator <TSource>
{
if (predicate is null)
{
Throw.ArgumentNullException(nameof(predicate));
}
return(new WhereIndexEnumerable <TEnumerable, TEnumerator, TSource>(in source, predicate));
}
public static AsyncPredicateAt <TSource> Combine <TSource>(AsyncPredicateAt <TSource> first, AsyncPredicateAt <TSource> second) => async(item, index, cancellation) => await first(item, index, cancellation).ConfigureAwait(false) && await second(item, index, cancellation).ConfigureAwait(false);
static async ValueTask <Option <TSource> > FirstAsync <TEnumerable, TEnumerator, TSource>(this TEnumerable source, AsyncPredicateAt <TSource> predicate, CancellationToken cancellationToken)
where TEnumerable : notnull, IAsyncValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IAsyncEnumerator <TSource>
{
var enumerator = source.GetAsyncEnumerator(cancellationToken);
await using (enumerator.ConfigureAwait(false))
{
checked
{
for (var index = 0; await enumerator.MoveNextAsync().ConfigureAwait(false); index++)
{
var item = enumerator.Current;
if (await predicate(item, index, cancellationToken).ConfigureAwait(false))
{
return(Option.Some(item));
}
}
}
}
return(Option.None);
}
static async ValueTask <LargeArrayBuilder <TSource> > ToArrayBuilderAsync <TEnumerable, TEnumerator, TSource>(TEnumerable source, AsyncPredicateAt <TSource> predicate, ArrayPool <TSource> arrayPool, CancellationToken cancellationToken)
where TEnumerable : notnull, IAsyncValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IAsyncEnumerator <TSource>
{
Debug.Assert(arrayPool is object);
var builder = new LargeArrayBuilder <TSource>(arrayPool);
var enumerator = source.GetAsyncEnumerator();
await using (enumerator.ConfigureAwait(false))
{
checked
{
for (var index = 0; await enumerator.MoveNextAsync().ConfigureAwait(false); index++)
{
cancellationToken.ThrowIfCancellationRequested();
var item = enumerator.Current;
if (await predicate(item, index, cancellationToken).ConfigureAwait(false))
{
builder.Add(item);
}
}
}
}
return(builder);
}
