Merge pull request #829 from symform/httpwebreq-async-ssl

[mono.git] / mcs / class / System.Core / System.Linq / Enumerable.cs

diff --git a/mcs/class/System.Core/System.Linq/Enumerable.cs b/mcs/class/System.Core/System.Linq/Enumerable.cs
index 89547d0a059a2f196ca70cd897616932fcbcc897..23805636c6b6236d00dc7b20fce0feeb83ffd659 100644 (file)
--- a/mcs/class/System.Core/System.Linq/Enumerable.cs
+++ b/mcs/class/System.Core/System.Linq/Enumerable.cs
@@ -744,6 +744,12 @@ namespace System.Linq
                        if (list != null)
                                return list [index];
 
+#if NET_4_5
+                       var readOnlyList = source as IReadOnlyList<TSource>;
+                       if (readOnlyList != null)
+                               return readOnlyList[index];
+#endif
+
                        return source.ElementAt (index, Fallback.Throw);
                }
 
@@ -762,6 +768,12 @@ namespace System.Linq
                        if (list != null)
                                return index < list.Count ? list [index] : default (TSource);
 
+#if NET_4_5
+                       var readOnlyList = source as IReadOnlyList<TSource>;
+                       if (readOnlyList != null)
+                               return index < readOnlyList.Count ? readOnlyList [index] : default (TSource);
+#endif
+
                        return source.ElementAt (index, Fallback.Default);
                }
 
@@ -1099,7 +1111,7 @@ namespace System.Linq
 
                        foreach (TOuter element in outer) {
                                TKey outerKey = outerKeySelector (element);
-                               if (innerKeys.Contains (outerKey))
+                               if (outerKey != null && innerKeys.Contains (outerKey))
                                        yield return resultSelector (element, innerKeys [outerKey]);
                                else
                                        yield return resultSelector (element, Empty<TInner> ());
@@ -1166,7 +1178,7 @@ namespace System.Linq
 
                        foreach (TOuter element in outer) {
                                TKey outerKey = outerKeySelector (element);
-                               if (innerKeys.Contains (outerKey)) {
+                               if (outerKey != null && innerKeys.Contains (outerKey)) {
                                        foreach (TInner innerElement in innerKeys [outerKey])
                                                yield return resultSelector (element, innerElement);
                                }
@@ -2885,7 +2897,7 @@ namespace System.Linq
                                collection.CopyTo (array, 0);
                                return array;
                        }
-                       
+
                        int pos = 0;
                        array = EmptyOf<TSource>.Instance;
                        foreach (var element in source) {
@@ -3105,6 +3117,11 @@ namespace System.Linq
                {
                        Check.SourceAndPredicate (source, predicate);
 
+                       // It cannot be IList<TSource> because it may break on user implementation
+                       var array = source as TSource[];
+                       if (array != null)
+                               return CreateWhereIterator (array, predicate);
+
                        return CreateWhereIterator (source, predicate);
                }
 
@@ -3115,14 +3132,27 @@ namespace System.Linq
                                        yield return element;
                }
 
+               static IEnumerable<TSource> CreateWhereIterator<TSource> (TSource[] source, Func<TSource, bool> predicate)
+               {
+                       for (int i = 0; i < source.Length; ++i) {
+                               var element = source [i];
+                               if (predicate (element))
+                                       yield return element;
+                       }
+               }       
+
                public static IEnumerable<TSource> Where<TSource> (this IEnumerable<TSource> source, Func<TSource, int, bool> predicate)
                {
                        Check.SourceAndPredicate (source, predicate);
 
+                       var array = source as TSource[];
+                       if (array != null)
+                               return CreateWhereIterator (array, predicate);
+
                        return CreateWhereIterator (source, predicate);
                }
 
-               static IEnumerable<TSource> CreateWhereIterator<TSource> (this IEnumerable<TSource> source, Func<TSource, int, bool> predicate)
+               static IEnumerable<TSource> CreateWhereIterator<TSource> (IEnumerable<TSource> source, Func<TSource, int, bool> predicate)
                {
                        int counter = 0;
                        foreach (TSource element in source) {
@@ -3132,6 +3162,15 @@ namespace System.Linq
                        }
                }
 
+               static IEnumerable<TSource> CreateWhereIterator<TSource> (TSource[] source, Func<TSource, int, bool> predicate)
+               {
+                       for (int i = 0; i < source.Length; ++i) {
+                               var element = source [i];
+                               if (predicate (element, i))
+                                       yield return element;
+                       }
+               }
+
                #endregion
 
                internal static ReadOnlyCollection<TSource> ToReadOnlyCollection<TSource> (this IEnumerable<TSource> source)