BitmapSequentialContainsTrue.cs

using System.Collections.Generic;
using System.Linq;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Order;

namespace Benchmarkator.Bitmap;

[Orderer(SummaryOrderPolicy.FastestToSlowest)]
public class BitmapSequentialContainsTrue
{
    [Params(32, 1024)]
    public int Length;

    private System.Collections.BitArray _bitArray = null!;
    private Dictionary<int, bool> _map = null!;
    private HashSet<int> _set = null!;

    [GlobalSetup]
    public void Setup()
    {
        // only `true` values are stored, missing value means bit is not set
        _bitArray = new System.Collections.BitArray(Length, true);

        _map = new Dictionary<int, bool>(
            Enumerable
                .Range(0, Length)
                .Select(v => KeyValuePair.Create(v, true)));

        _set = new HashSet<int>(
            Enumerable.Range(0, Length));
    }

    [Benchmark]
    public bool BitArrayContains()
    {
        var contains = false;
        for (var i = 0; i < Length; i++)
        {
            // or: `_bitArray[i]`
            contains |= _bitArray.Get(i);
        }

        return contains;
    }

    [Benchmark]
    public bool DictionaryContains()
    {
        var contains = false;
        for (var i = 0; i < Length; i++)
        {
            // NB! value is `true`, see setup
            // (alternatively: `_map.ContainsKey(i)`)
            contains |= _map[i];
        }

        return contains;
    }

    [Benchmark]
    public bool SetContains()
    {
        var contains = false;
        for (var i = 0; i < Length; i++)
        {
            contains |= _set.Contains(i);
        }

        return contains;
    }
}