Thanks to visit codestin.com
Credit goes to github.com

Skip to content

Improve performance of Enumerable.ToDictionary() #96574

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jan 8, 2024
Merged

Improve performance of Enumerable.ToDictionary() #96574

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
55 changes: 15 additions & 40 deletions src/libraries/System.Linq/src/System/Linq/ToCollection.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@

using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace System.Linq
{
Expand Down Expand Up @@ -108,23 +109,22 @@ public static Dictionary<TKey, TSource> ToDictionary<TSource, TKey>(this IEnumer
ThrowHelper.ThrowArgumentNullException(ExceptionArgument.keySelector);
}

int capacity = 0;
if (source is ICollection<TSource> collection)
if (source.TryGetNonEnumeratedCount(out int capacity))
{
capacity = collection.Count;
if (capacity == 0)
{
return new Dictionary<TKey, TSource>(comparer);
}

if (collection is TSource[] array)
if (source is TSource[] array)
{
return ToDictionary(array, keySelector, comparer);
return SpanToDictionary(array, keySelector, comparer);
}

if (collection is List<TSource> list)
if (source is List<TSource> list)
{
return ToDictionary(list, keySelector, comparer);
ReadOnlySpan<TSource> span = CollectionsMarshal.AsSpan(list);
return SpanToDictionary(span, keySelector, comparer);
}
}

Expand All @@ -137,25 +137,13 @@ public static Dictionary<TKey, TSource> ToDictionary<TSource, TKey>(this IEnumer
return d;
}

private static Dictionary<TKey, TSource> ToDictionary<TSource, TKey>(TSource[] source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? comparer) where TKey : notnull
private static Dictionary<TKey, TSource> SpanToDictionary<TSource, TKey>(ReadOnlySpan<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? comparer) where TKey : notnull
{
Dictionary<TKey, TSource> d = new Dictionary<TKey, TSource>(source.Length, comparer);
for (int i = 0; i < source.Length; i++)
{
d.Add(keySelector(source[i]), source[i]);
}

return d;
}

private static Dictionary<TKey, TSource> ToDictionary<TSource, TKey>(List<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? comparer) where TKey : notnull
{
Dictionary<TKey, TSource> d = new Dictionary<TKey, TSource>(source.Count, comparer);
foreach (TSource element in source)
{
d.Add(keySelector(element), element);
}

return d;
}

Expand All @@ -179,23 +167,22 @@ public static Dictionary<TKey, TElement> ToDictionary<TSource, TKey, TElement>(t
ThrowHelper.ThrowArgumentNullException(ExceptionArgument.elementSelector);
}

int capacity = 0;
if (source is ICollection<TSource> collection)
if (source.TryGetNonEnumeratedCount(out int capacity))
{
capacity = collection.Count;
if (capacity == 0)
{
return new Dictionary<TKey, TElement>(comparer);
}

if (collection is TSource[] array)
if (source is TSource[] array)
{
return ToDictionary(array, keySelector, elementSelector, comparer);
return SpanToDictionary(array, keySelector, elementSelector, comparer);
}

if (collection is List<TSource> list)
if (source is List<TSource> list)
{
return ToDictionary(list, keySelector, elementSelector, comparer);
ReadOnlySpan<TSource> span = CollectionsMarshal.AsSpan(list);
return SpanToDictionary(span, keySelector, elementSelector, comparer);
}
}

Expand All @@ -208,25 +195,13 @@ public static Dictionary<TKey, TElement> ToDictionary<TSource, TKey, TElement>(t
return d;
}

private static Dictionary<TKey, TElement> ToDictionary<TSource, TKey, TElement>(TSource[] source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey>? comparer) where TKey : notnull
private static Dictionary<TKey, TElement> SpanToDictionary<TSource, TKey, TElement>(ReadOnlySpan<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey>? comparer) where TKey : notnull
{
Dictionary<TKey, TElement> d = new Dictionary<TKey, TElement>(source.Length, comparer);
for (int i = 0; i < source.Length; i++)
{
d.Add(keySelector(source[i]), elementSelector(source[i]));
}

return d;
}

private static Dictionary<TKey, TElement> ToDictionary<TSource, TKey, TElement>(List<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey>? comparer) where TKey : notnull
{
Dictionary<TKey, TElement> d = new Dictionary<TKey, TElement>(source.Count, comparer);
foreach (TSource element in source)
{
d.Add(keySelector(element), elementSelector(element));
}

return d;
}

Expand Down