Import YamlDotNet.

Assets/YamlDotNet/Core/HashCode.cs

@@ -0,0 +1,60 @@
+// This file is part of YamlDotNet - A .NET library for YAML.
+// Copyright (c) Antoine Aubry and contributors
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of
+// this software and associated documentation files (the "Software"), to deal in
+// the Software without restriction, including without limitation the rights to
+// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+// of the Software, and to permit persons to whom the Software is furnished to do
+// so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+namespace YamlDotNet.Core
+{
+    /// <summary>
+    /// Supports implementations of <see cref="object.GetHashCode"/> by providing methods to combine two hash codes.
+    /// </summary>
+    internal static class HashCode
+    {
+        /// <summary>
+        /// Combines two hash codes.
+        /// </summary>
+        /// <param name="h1">The first hash code.</param>
+        /// <param name="h2">The second hash code.</param>
+        /// <returns></returns>
+        public static int CombineHashCodes(int h1, int h2)
+        {
+            return ((h1 << 5) + h1) ^ h2;
+        }
+
+        public static int CombineHashCodes(int h1, object? o2)
+        {
+            return CombineHashCodes(h1, GetHashCode(o2));
+        }
+
+        public static int CombineHashCodes(object? first, params object?[] others)
+        {
+            var hashCode = GetHashCode(first);
+            foreach (var other in others)
+            {
+                hashCode = CombineHashCodes(hashCode, other);
+            }
+            return hashCode;
+        }
+
+        private static int GetHashCode(object? obj)
+        {
+            return obj != null ? obj.GetHashCode() : 0;
+        }
+    }
+}