Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/ModelBinding/ValueProviderCollection.cs

@@ -0,0 +1,55 @@
+namespace System.Web.ModelBinding {
+    using System;
+    using System.Collections.Generic;
+    using System.Collections.ObjectModel;
+    using System.Linq;
+
+    public class ValueProviderCollection : Collection<IValueProvider>, IValueProvider, IUnvalidatedValueProvider {
+
+        public ValueProviderCollection() {
+        }
+
+        public ValueProviderCollection(IList<IValueProvider> list)
+            : base(list) {
+        }
+
+        public virtual bool ContainsPrefix(string prefix) {
+            return this.Any(vp => vp.ContainsPrefix(prefix));
+        }
+
+        public virtual ValueProviderResult GetValue(string key) {
+            return GetValue(key, skipValidation: false);
+        }
+
+        public virtual ValueProviderResult GetValue(string key, bool skipValidation) {
+            return (from provider in this
+                    let result = GetValueFromProvider(provider, key, skipValidation)
+                    where result != null
+                    select result).FirstOrDefault();
+        }
+
+        internal static ValueProviderResult GetValueFromProvider(IValueProvider provider, string key, bool skipValidation) {
+            // Since IUnvalidatedValueProvider is a superset of IValueProvider, it's always OK to use the
+            // IUnvalidatedValueProvider-supplied members if they're present. Otherwise just call the
+            // normal IValueProvider members.
+
+            IUnvalidatedValueProvider unvalidatedProvider = provider as IUnvalidatedValueProvider;
+            return (unvalidatedProvider != null) ? unvalidatedProvider.GetValue(key, skipValidation) : provider.GetValue(key);
+        }
+
+        protected override void InsertItem(int index, IValueProvider item) {
+            if (item == null) {
+                throw new ArgumentNullException("item");
+            }
+            base.InsertItem(index, item);
+        }
+
+        protected override void SetItem(int index, IValueProvider item) {
+            if (item == null) {
+                throw new ArgumentNullException("item");
+            }
+            base.SetItem(index, item);
+        }
+
+    }
+}