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Code Issues

style/perf: reduce complexity of MinMax and MinMaxBy

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Oliver Booth 2023-03-28 16:28:59 +01:00
parent 121c3a388a
commit e0bdaaddce
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GPG Key ID: 20BEB9DC87961025
1 changed files with 101 additions and 78 deletions
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175
X10D/src/Linq/EnumerableExtensions.cs
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@ -1,4 +1,6 @@
using System.Runtime.InteropServices;
#if NET5_0_OR_GREATER
using System.Runtime.InteropServices;
#endif
namespace X10D.Linq;
@ -50,37 +52,15 @@ public static class EnumerableExtensions
#endif
comparer ??= Comparer<T>.Default;
T? minValue;
T? maxValue;
// ReSharper disable once PossibleMultipleEnumeration
if (source.TryGetSpan(out ReadOnlySpan<T> span))
{
if (span.IsEmpty)
{
throw new InvalidOperationException("Source contains no elements");
return MinMaxSpan(comparer, span);
}
minValue = span[0];
maxValue = minValue;
for (var index = 1; (uint)index < (uint)span.Length; index++)
{
T current = span[index];
if (comparer.Compare(current, minValue) < 0)
{
minValue = current;
}
if (comparer.Compare(current, maxValue) > 0)
{
maxValue = current;
}
}
return (minValue, maxValue);
}
T? minValue;
T? maxValue;
// ReSharper disable once PossibleMultipleEnumeration
using (IEnumerator<T> enumerator = source.GetEnumerator())
@ -175,37 +155,15 @@ public static class EnumerableExtensions
#endif
comparer ??= Comparer<TResult>.Default;
TResult? minValue;
TResult? maxValue;
// ReSharper disable once PossibleMultipleEnumeration
if (source.TryGetSpan(out ReadOnlySpan<TSource> span))
{
if (span.IsEmpty)
{
throw new InvalidOperationException("Source contains no elements");
return MinMaxSpan(selector, comparer, span);
}
minValue = selector(span[0]);
maxValue = minValue;
for (var index = 1; (uint)index < (uint)span.Length; index++)
{
TResult current = selector(span[index]);
if (minValue is null || comparer.Compare(current, minValue) < 0)
{
minValue = current;
}
if (maxValue is null || comparer.Compare(current, maxValue) > 0)
{
maxValue = current;
}
}
return (minValue, maxValue);
}
TResult? minValue;
TResult? maxValue;
// ReSharper disable once PossibleMultipleEnumeration
using (IEnumerator<TSource> enumerator = source.GetEnumerator())
@ -305,31 +263,7 @@ public static class EnumerableExtensions
// ReSharper disable once PossibleMultipleEnumeration
if (source.TryGetSpan(out ReadOnlySpan<TSource> span))
{
if (span.IsEmpty)
{
throw new InvalidOperationException("Source contains no elements");
}
minValue = span[0];
maxValue = minValue;
for (var index = 1; (uint)index < (uint)span.Length; index++)
{
TSource current = span[index];
TResult transformedCurrent = keySelector(current);
if (minValue is null || comparer.Compare(transformedCurrent, keySelector(minValue)) < 0)
{
minValue = current;
}
if (maxValue is null || comparer.Compare(transformedCurrent, keySelector(maxValue)) > 0)
{
maxValue = current;
}
}
return (minValue, maxValue);
return MinMaxSelectedSpan(keySelector, comparer, span);
}
// ReSharper disable once PossibleMultipleEnumeration
@ -363,6 +297,95 @@ public static class EnumerableExtensions
return (minValue, maxValue);
}
private static (T? Minimum, T? Maximum) MinMaxSpan<T>(IComparer<T> comparer, ReadOnlySpan<T> span)
{
if (span.IsEmpty)
{
throw new InvalidOperationException("Source contains no elements");
}
T minValue = span[0];
T maxValue = minValue;
for (var index = 1; (uint)index < (uint)span.Length; index++)
{
T current = span[index];
if (comparer.Compare(current, minValue) < 0)
{
minValue = current;
}
if (comparer.Compare(current, maxValue) > 0)
{
maxValue = current;
}
}
return (minValue, maxValue);
}
private static (TSource? Minimum, TSource? Maximum) MinMaxSelectedSpan<TSource, TResult>(Func<TSource, TResult> keySelector,
IComparer<TResult> comparer,
ReadOnlySpan<TSource> span)
{
if (span.IsEmpty)
{
throw new InvalidOperationException("Source contains no elements");
}
TSource minValue = span[0];
TSource maxValue = minValue;
for (var index = 1; (uint)index < (uint)span.Length; index++)
{
TSource current = span[index];
TResult transformedCurrent = keySelector(current);
if (minValue is null || comparer.Compare(transformedCurrent, keySelector(minValue)) < 0)
{
minValue = current;
}
if (maxValue is null || comparer.Compare(transformedCurrent, keySelector(maxValue)) > 0)
{
maxValue = current;
}
}
return (minValue, maxValue);
}
private static (TResult?, TResult?) MinMaxSpan<TSource, TResult>(Func<TSource, TResult> selector,
IComparer<TResult> comparer,
ReadOnlySpan<TSource> span)
{
if (span.IsEmpty)
{
throw new InvalidOperationException("Source contains no elements");
}
TResult minValue = selector(span[0]);
TResult maxValue = minValue;
for (var index = 1; (uint)index < (uint)span.Length; index++)
{
TResult current = selector(span[index]);
if (minValue is null || comparer.Compare(current, minValue) < 0)
{
minValue = current;
}
if (maxValue is null || comparer.Compare(current, maxValue) > 0)
{
maxValue = current;
}
}
return (minValue, maxValue);
}
private static bool TryGetSpan<TSource>(this IEnumerable<TSource> source, out ReadOnlySpan<TSource> span)
{
#if NET6_0_OR_GREATER