Add collection related interfaces and classes

nanoFramework.CoreLibrary/CoreLibrary.nfproj

@@ -38,7 +38,7 @@
     <AllowedOutputExtensionsInPackageBuildOutputFolder>$(AllowedOutputExtensionsInPackageBuildOutputFolder);.pdb</AllowedOutputExtensionsInPackageBuildOutputFolder>
     <RestorePackagesWithLockFile>true</RestorePackagesWithLockFile>
     <RestoreLockedMode Condition="'$(TF_BUILD)' == 'True' or '$(ContinuousIntegrationBuild)' == 'True'">true</RestoreLockedMode>
-    <LangVersion>default</LangVersion>
+    <LangVersion>13.0</LangVersion>
   </PropertyGroup>
   <PropertyGroup>
     <SignAssembly>true</SignAssembly>
@@ -66,10 +66,12 @@
     <Compile Include="System\AppDomainUnloadedException.cs" />
     <Compile Include="System\ApplicationException.cs" />
     <Compile Include="System\ArgumentException.cs" />
+    <Compile Include="System\Array.Enumerators.cs" />
     <Compile Include="System\ArrayTypeMismatchException.cs" />
-    <Compile Include="System\Collections\Generic\ComparerHelpers.cs" />
     <Compile Include="System\Collections\Generic\Comparer.cs" />
+    <Compile Include="System\Collections\Generic\IEnumerable.cs" />
     <Compile Include="System\Collections\Generic\IComparer.cs" />
+    <Compile Include="System\Collections\Generic\IEnumerator.cs" />
     <Compile Include="System\Diagnostics\StackTraceHiddenAttribute.cs" />
     <Compile Include="System\Nullable.cs" />
     <Compile Include="System\Runtime\InteropServices\InAttribute .cs" />
@@ -260,4 +262,4 @@
   <Import Project="..\packages\Microsoft.SourceLink.Common.1.1.1\build\Microsoft.SourceLink.Common.targets" Condition="Exists('..\packages\Microsoft.SourceLink.Common.1.1.1\build\Microsoft.SourceLink.Common.targets')" />
   <Import Project="..\packages\Microsoft.SourceLink.GitHub.1.1.1\build\Microsoft.SourceLink.GitHub.targets" Condition="Exists('..\packages\Microsoft.SourceLink.GitHub.1.1.1\build\Microsoft.SourceLink.GitHub.targets')" />
   <Import Project="..\packages\Nerdbank.GitVersioning.3.7.115\build\Nerdbank.GitVersioning.targets" Condition="Exists('..\packages\Nerdbank.GitVersioning.3.7.115\build\Nerdbank.GitVersioning.targets')" />
-</Project>
+</Project>

nanoFramework.CoreLibrary/System/Array.Enumerators.cs

@@ -0,0 +1,101 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Reflection;
+using System.Runtime.CompilerServices;
+
+#nullable enable
+
+namespace System
+{
+    internal abstract class SZGenericArrayEnumeratorBase : IDisposable
+    {
+        protected int _index;
+        protected readonly int _endIndex;
+
+        protected SZGenericArrayEnumeratorBase(int endIndex)
+        {
+            _index = -1;
+            _endIndex = endIndex;
+        }
+
+        public bool MoveNext()
+        {
+            int index = _index + 1;
+
+            if ((uint)index < (uint)_endIndex)
+            {
+                _index = index;
+
+                return true;
+            }
+
+            _index = _endIndex;
+
+            return false;
+        }
+
+        public void Reset() => _index = -1;
+
+        public void Dispose()
+        {
+        }
+    }
+
+    internal sealed class SZGenericArrayEnumerator<T> : SZGenericArrayEnumeratorBase, IEnumerator<T>
+    {
+        private readonly T[]? _array;
+
+        /// <summary>Provides an empty enumerator singleton.</summary>
+        /// <remarks>
+        /// If the consumer is using SZGenericArrayEnumerator elsewhere or is otherwise likely
+        /// to be using T[] elsewhere, this singleton should be used.  Otherwise, GenericEmptyEnumerator's
+        /// singleton should be used instead, as it doesn't reference T[] in order to reduce footprint.
+        /// </remarks>
+        internal static readonly SZGenericArrayEnumerator<T> Empty = new SZGenericArrayEnumerator<T>(null, 0);
+
+        internal SZGenericArrayEnumerator(T[]? array, int endIndex)
+            : base(endIndex)
+        {
+            Debug.Assert(array == null || endIndex == array.Length);
+            _array = array;
+        }
+
+        public T Current
+        {
+            get
+            {
+                if ((uint)_index >= (uint)_endIndex)
+                {
+                    throw new InvalidOperationException();
+                }
+
+                return _array![_index];
+            }
+        }
+
+        object? IEnumerator.Current => Current;
+    }
+
+    internal abstract class GenericEmptyEnumeratorBase : IDisposable, IEnumerator
+    {
+#pragma warning disable CA1822 // https://github.com/dotnet/roslyn-analyzers/issues/5911
+        public bool MoveNext() => false;
+
+        public object Current
+        {
+            get
+            {
+                return default;
+            }
+        }
+
+        public void Reset() { }
+
+        public void Dispose() { }
+#pragma warning restore CA1822
+    }
+}