Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data.Entity/System/Data/Metadata/ObjectLayer/KnownAssembliesSet.cs

@@ -0,0 +1,90 @@
+//---------------------------------------------------------------------
+// <copyright file="KnownAssembliesSet.cs" company="Microsoft">
+//      Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//
+// @owner       [....]
+// @backupOwner [....]
+//---------------------------------------------------------------------
+
+using System;
+using System.Linq;
+using System.Reflection;
+using System.Collections.Generic;
+using System.Diagnostics;
+
+namespace System.Data.Metadata.Edm
+{
+    /// <summary>
+    /// This class is responsible for keeping track of which assemblies we have already 
+    /// considered so we don't reconsider them again. 
+    /// 
+    /// The current rules for an assembly to be "seen" is
+    ///     1. It is already in our dictionary
+    ///     AND
+    ///         1.  We are in attribute loading mode
+    ///         OR
+    ///         2. We have seen it already with a non null EdmItemCollection
+    ///         OR
+    ///         3. We are seeing it with a null EdmItemCollection this time
+    /// </summary>
+    internal class KnownAssembliesSet 
+    {
+        private Dictionary<Assembly, KnownAssemblyEntry> _assemblies;
+        internal KnownAssembliesSet()
+        {
+            _assemblies = new Dictionary<Assembly, KnownAssemblyEntry>();
+        }
+
+        internal KnownAssembliesSet(KnownAssembliesSet set)
+        {
+            _assemblies = new Dictionary<Assembly, KnownAssemblyEntry>(set._assemblies);
+        }
+
+        internal bool TryGetKnownAssembly(Assembly assembly, object loaderCookie, EdmItemCollection itemCollection, out KnownAssemblyEntry entry)
+        {
+            if (!_assemblies.TryGetValue(assembly, out entry))
+            {
+                return false;
+            }
+
+            if (!entry.HaveSeenInCompatibleContext(loaderCookie, itemCollection))
+            {
+                return false;
+            }
+
+            return true;
+        }
+
+        internal IEnumerable<Assembly> Assemblies
+        {
+            get { return _assemblies.Keys; }
+        }
+
+        public IEnumerable<KnownAssemblyEntry> GetEntries(object loaderCookie, EdmItemCollection itemCollection)
+        {
+            return _assemblies.Values.Where(e => e.HaveSeenInCompatibleContext(loaderCookie, itemCollection));
+        }
+
+        internal bool Contains(Assembly assembly, object loaderCookie, EdmItemCollection itemCollection)
+        {
+            KnownAssemblyEntry entry;
+            return TryGetKnownAssembly(assembly, loaderCookie, itemCollection, out entry);
+        }
+
+        internal void Add(Assembly assembly, KnownAssemblyEntry knownAssemblyEntry)
+        {
+            KnownAssemblyEntry current;
+            if (_assemblies.TryGetValue(assembly, out current))
+            {
+                Debug.Assert(current.SeenWithEdmItemCollection != knownAssemblyEntry.SeenWithEdmItemCollection &&
+                    knownAssemblyEntry.SeenWithEdmItemCollection, "should only be updating if we haven't seen it with an edmItemCollection yet.");
+                _assemblies[assembly] = knownAssemblyEntry;
+            }
+            else
+            {
+                _assemblies.Add(assembly, knownAssemblyEntry);
+            }
+        }
+    }
+}