Add net5.0 target framework

src/Spectre.Console/Extensions/EnumerableExtensions.cs

@@ -0,0 +1,87 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Spectre.Console.Internal
+{
+    internal static class EnumerableExtensions
+    {
+        public static int GetCount<T>(this IEnumerable<T> source)
+        {
+            if (source is IList<T> list)
+            {
+                return list.Count;
+            }
+
+            if (source is T[] array)
+            {
+                return array.Length;
+            }
+
+            return source.Count();
+        }
+
+        public static void ForEach<T>(this IEnumerable<T> source, Action<T> action)
+        {
+            foreach (var item in source)
+            {
+                action(item);
+            }
+        }
+
+        public static bool AnyTrue(this IEnumerable<bool> source)
+        {
+            return source.Any(b => b);
+        }
+
+        public static IEnumerable<(int Index, bool First, bool Last, T Item)> Enumerate<T>(this IEnumerable<T> source)
+        {
+            if (source is null)
+            {
+                throw new ArgumentNullException(nameof(source));
+            }
+
+            return Enumerate(source.GetEnumerator());
+        }
+
+        public static IEnumerable<(int Index, bool First, bool Last, T Item)> Enumerate<T>(this IEnumerator<T> source)
+        {
+            if (source is null)
+            {
+                throw new ArgumentNullException(nameof(source));
+            }
+
+            var first = true;
+            var last = !source.MoveNext();
+            T current;
+
+            for (var index = 0; !last; index++)
+            {
+                current = source.Current;
+                last = !source.MoveNext();
+                yield return (index, first, last, current);
+                first = false;
+            }
+        }
+
+        public static IEnumerable<TResult> SelectIndex<T, TResult>(this IEnumerable<T> source, Func<T, int, TResult> func)
+        {
+            return source.Select((value, index) => func(value, index));
+        }
+
+#if !NET5_0
+        public static IEnumerable<(TFirst First, TSecond Second)> Zip<TFirst, TSecond>(
+            this IEnumerable<TFirst> source, IEnumerable<TSecond> first)
+        {
+            return source.Zip(first, (first, second) => (first, second));
+        }
+#endif
+
+        public static IEnumerable<(TFirst First, TSecond Second, TThird Third)> Zip<TFirst, TSecond, TThird>(
+            this IEnumerable<TFirst> first, IEnumerable<TSecond> second, IEnumerable<TThird> third)
+        {
+            return first.Zip(second, (a, b) => (a, b))
+                .Zip(third, (a, b) => (a.a, a.b, b));
+        }
+    }
+}