Merge pull request #19 from nventive/dev/dr/IndexOfList

Add IndexOf on IList which accepts an IEqualiyComparer

src/Uno.Core.Tests/Collections/ListExtensionsFixture.cs

@@ -0,0 +1,74 @@
+// ******************************************************************
+// Copyright � 2015-2018 nventive inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// ******************************************************************
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Uno.Extensions;
+
+namespace Uno.Core.Tests.Collections
+{
+	[TestClass]
+	public class ListExtensionsFixture
+	{
+		private static readonly int[] list = new [] { 1, 2, 3};
+
+		[TestMethod]
+		public void AsReadOnly()
+		{
+			IList<int> list2 = new List<int>(list);
+
+			Assert.IsTrue(list2.AsReadOnly().IsReadOnly);
+		}
+
+		[TestMethod]
+		public void Adapt()
+		{
+			IList<string> adapter = list.Adapt<int, string>();
+
+			Assert.IsNotNull(adapter);
+		}
+
+		[TestMethod]
+		public void IndexOf_WithComparer()
+		{
+			var @true = new MyComparer((l, r) => true);
+			var @false = new MyComparer((l, r) => false);
+
+			Assert.AreEqual(0, new[] {1, 2, 3}.IndexOf(2, @true));
+			Assert.AreEqual(1, new[] {1, 2, 3}.IndexOf(2, EqualityComparer<object>.Default));
+			Assert.AreEqual(1, new[] {1, 2, 3}.IndexOf(2, default(IEqualityComparer)));
+			Assert.AreEqual(-1, new[] {1, 2, 3}.IndexOf(2, @false));
+
+			Assert.AreEqual(0, new[] {1, 2, 3}.IndexOf(-1, @true));
+			Assert.AreEqual(-1, new[] {1, 2, 3}.IndexOf(-1, EqualityComparer<object>.Default));
+			Assert.AreEqual(-1, new[] {1, 2, 3}.IndexOf(-1, default(IEqualityComparer)));
+			Assert.AreEqual(-1, new[] {1, 2, 3}.IndexOf(-1, @false));
+		}
+
+		private class MyComparer : IEqualityComparer
+		{
+			private readonly Func<object, object, bool> _equals;
+
+			public MyComparer(Func<object, object, bool> equals) => _equals = @equals;
+
+			public bool Equals(object left, object right) => _equals(left, right);
+
+			public int GetHashCode(object obj) => throw new System.NotImplementedException();
+		}
+	}
+}

src/Uno.Core/Collections/ListExtensions.cs

@@ -272,5 +272,30 @@ public static T FindNearestItem<T>(this IReadOnlyList<T> list, Func<T, bool> pre
 				.ToDivergentEnumerable(startingAt)
 				.FirstOrDefault(predicate);
 		}
+
+		/// <summary>
+		/// Determines the index of a specific item in the <see cref="IList"/>.
+		/// </summary>
+		/// <param name="list">The source list to look into.</param>
+		/// <param name="value">The object to locate in the <see cref="IList"/>.</param>
+		/// <param name="comparer">The comparer to use to locate the <paramref name="value" />.</param>
+		/// <returns>The index of value if found in the list; otherwise, -1.</returns>
+		public static int IndexOf(this IList list, object value, IEqualityComparer comparer)
+		{
+			if (comparer == null)
+			{
+				return list.IndexOf(value);
+			}
+
+			for (var i = 0; i < list.Count; i++)
+			{
+				if (comparer.Equals(value, list[i]))
+				{
+					return i;
+				}
+			}
+
+			return -1;
+		}
 	}
 }