同步

Packages/dev.yarnspinner.unity/Editor/Utility/Compare.cs

@@ -0,0 +1,44 @@
+/*
+Yarn Spinner is licensed to you under the terms found in the file LICENSE.md.
+*/
+
+using System.Collections.Generic;
+
+namespace Yarn.Unity.Editor
+{
+    // A simple class lets us use a delegate as an IEqualityComparer from
+    // https://stackoverflow.com/a/4607559
+    internal static class Compare
+    {
+        public static IEqualityComparer<T> By<T>(System.Func<T, T, bool> comparison)
+        {
+            return new DelegateComparer<T>(comparison);
+        }
+
+        private class DelegateComparer<T> : EqualityComparer<T>
+        {
+            private readonly System.Func<T, T, bool> comparison;
+
+            public DelegateComparer(System.Func<T, T, bool> identitySelector)
+            {
+                this.comparison = identitySelector;
+            }
+
+            public override bool Equals(T x, T y)
+            {
+                return comparison(x, y);
+            }
+
+            public override int GetHashCode(T obj)
+            {
+                // Force LINQ to never refer to the hash of an object by
+                // returning a constant for all values. This is inefficient
+                // because LINQ can't use an internal comparator, but we're
+                // already looking to use a delegate to do a more
+                // fine-grained test anyway, so we want to ensure that it's
+                // called.
+                return 0;
+            }
+        }
+    }
+}