Enumerable.Any.Benchmarks.cs

using System.Runtime.InteropServices;

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;

if(args is []) {
  args = ["--filter", "*"];
}//if

BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);

[MemoryDiagnoser]
public class Benchmarks
{
  private static readonly List<string> Input = [.. Enumerable.Range(0, 1000).Select(static item => item.ToString())];
  private static readonly string ToCompare = 555.ToString();

  [Benchmark(Baseline = true)]
  public bool EnumerableAny() => Input.Any(static item => item == ToCompare);

  [Benchmark]
  public bool ListExists() => Input.Exists(static item => item == ToCompare);

  [Benchmark]
  public bool ExtensionsAny() => Input.AsSpan().Any(ToCompare, static (item, state) => item == state);

  [Benchmark]
  public bool ManualLoop() {
    foreach(var item in Input) {
      if(item == ToCompare) {
        return true;
      }//if
    }//for
    return false;
  }
}

internal static class Extensions
{
  public static bool Any<TSource, TState>(this Span<TSource> source, TState state, Func<TSource, TState, bool> predicate) {
    ArgumentNullException.ThrowIfNull(predicate);

    for(var index = 0; index < source.Length; index++) {
      if(predicate(source[index], state)) {
        return true;
      }//if
    }//for

    return false;
  }

  public static Span<TSource> AsSpan<TSource>(this List<TSource> source) => CollectionsMarshal.AsSpan(source);
}

/*
| Method        | Mean     | Error     | StdDev    | Ratio | Allocated | Alloc Ratio |
|-------------- |---------:|----------:|----------:|------:|----------:|------------:|
| EnumerableAny | 4.272 us | 0.0518 us | 0.0432 us |  1.00 |      40 B |        1.00 |
| ListExists    | 1.670 us | 0.0112 us | 0.0099 us |  0.39 |         - |        0.00 |
| ExtensionsAny | 1.915 us | 0.0307 us | 0.0420 us |  0.45 |         - |        0.00 |
| ManualLoop    | 1.491 us | 0.0118 us | 0.0098 us |  0.35 |         - |        0.00 |
*/