natural string comparer

Chaos.Common/Comparers/NaturalStringComparer.cs

@@ -0,0 +1,56 @@
+namespace Chaos.Common.Comparers;
+
+/// <summary>
+///     A natural string comparer intended to work similarly to how windows orders files. Strings with numbers will be
+///     compared numerically, rather than lexicographically.
+/// </summary>
+public class NaturalStringComparer : IComparer<string>
+{
+    /// <inheritdoc />
+    public int Compare(string? x, string? y)
+    {
+        if ((x == null) && (y == null))
+            return 0;
+
+        if (x == null)
+            return -1;
+
+        if (y == null)
+            return 1;
+
+        var ix = 0;
+        var iy = 0;
+
+        while ((ix < x.Length) && (iy < y.Length))
+            if (char.IsDigit(x[ix]) && char.IsDigit(y[iy]))
+            {
+                var lx = 0;
+                var ly = 0;
+
+                while ((ix < x.Length) && char.IsDigit(x[ix]))
+                {
+                    lx = lx * 10 + (x[ix] - '0');
+                    ix++;
+                }
+
+                while ((iy < y.Length) && char.IsDigit(y[iy]))
+                {
+                    ly = ly * 10 + (y[iy] - '0');
+                    iy++;
+                }
+
+                if (lx != ly)
+                    return lx.CompareTo(ly);
+            } else
+            {
+                if (x[ix] != y[iy])
+                    return x[ix]
+                        .CompareTo(y[iy]);
+
+                ix++;
+                iy++;
+            }
+
+        return x.Length.CompareTo(y.Length);
+    }
+}