Imported Upstream version 4.8.0.309

Former-commit-id: 5f9c6ae75f295e057a7d2971f3a6df4656fa8850

external/cecil-legacy/Test/Mono.Cecil.Tests/Linq.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+
+using Mono;
+
+#if !NET_3_5 && !NET_4_0
+
+namespace System.Linq {
+
+	static class Enumerable {
+
+		public static IEnumerable<TRet> Select<TItem, TRet> (this IEnumerable<TItem> self, Func<TItem, TRet> selector)
+		{
+			foreach (var item in self)
+				yield return selector (item);
+		}
+
+		public static IEnumerable<T> Where<T> (this IEnumerable<T> self, Func<T, bool> predicate)
+		{
+			foreach (var item in self)
+				if (predicate (item))
+					yield return item;
+		}
+
+		public static List<T> ToList<T> (this IEnumerable<T> self)
+		{
+			return new List<T> (self);
+		}
+
+		public static T [] ToArray<T> (this IEnumerable<T> self)
+		{
+			return self.ToList ().ToArray ();
+		}
+
+		public static T First<T> (this IEnumerable<T> self)
+		{
+			using (var enumerator = self.GetEnumerator ()) {
+				if (!enumerator.MoveNext ())
+					throw new InvalidOperationException ();
+
+				return enumerator.Current;
+			}
+		}
+	}
+}
+
+#endif