Variants - invariant segments, property values

src/Umbraco.Core/Collections/CompositeIntStringKey.cs

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+using System;
+
+namespace Umbraco.Core.Collections
+{
+    /// <summary>
+    /// Represents a composite key of (int, string) for fast dictionaries.
+    /// </summary>
+    /// <remarks>
+    /// <para>The integer part of the key must be greater than, or equal to, zero.</para>
+    /// <para>The string part of the key is case-insensitive.</para>
+    /// <para>Null is a valid value for both parts.</para>
+    /// </remarks>
+    public struct CompositeIntStringKey : IEquatable<CompositeIntStringKey>
+    {
+        private readonly int _key1;
+        private readonly string _key2;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="CompositeIntStringKey"/> struct.
+        /// </summary>
+        public CompositeIntStringKey(int? key1, string key2)
+        {
+            if (key1 < 0) throw new ArgumentOutOfRangeException(nameof(key1));
+            _key1 = key1 ?? -1;
+            _key2 = key2?.ToLowerInvariant() ?? "NULL";
+        }
+
+        public bool Equals(CompositeIntStringKey other)
+            => _key2 == other._key2 && _key1 == other._key1;
+
+        public override bool Equals(object obj)
+            => obj is CompositeIntStringKey other && _key2 == other._key2 && _key1 == other._key1;
+
+        public override int GetHashCode()
+            => _key2.GetHashCode() * 31 + _key1;
+
+        public static bool operator ==(CompositeIntStringKey key1, CompositeIntStringKey key2)
+            => key1._key2 == key2._key2 && key1._key1 == key2._key1;
+
+        public static bool operator !=(CompositeIntStringKey key1, CompositeIntStringKey key2)
+            => key1._key2 != key2._key2 || key1._key1 != key2._key1;
+    }
+}