Add overload of Cache.AddOrUpdate(IEnumerable) which accepts a compar…

…er. Fixes #553 (#560)
reactivemarbles · Feb 14, 2022 · 8459c58 · 8459c58
1 parent 7e56818
commit 8459c58
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Showing 3 changed files with 70 additions and 12 deletions.
diff --git a/src/DynamicData/Cache/ISourceUpdater.cs b/src/DynamicData/Cache/ISourceUpdater.cs
@@ -29,6 +29,13 @@ public interface ISourceUpdater<TObject, TKey> : ICacheUpdater<TObject, TKey>
         /// <param name="items">The items.</param>
         void AddOrUpdate(IEnumerable<TObject> items);
 
+        /// <summary>
+        /// Adds or changes the specified items.
+        /// </summary>
+        /// <param name="items">The items.</param>
+        /// <param name="comparer">The comparer.</param>
+        void AddOrUpdate(IEnumerable<TObject> items, IEqualityComparer<TObject> comparer);
+
         /// <summary>
         /// Adds or updates the item.
         /// </summary>
@@ -86,4 +93,4 @@ public interface ISourceUpdater<TObject, TKey> : ICacheUpdater<TObject, TKey>
         /// <param name="item">The item.</param>
         void Remove(TObject item);
     }
-}
+}
diff --git a/src/DynamicData/Cache/Internal/CacheUpdater.cs b/src/DynamicData/Cache/Internal/CacheUpdater.cs
@@ -44,15 +44,8 @@ public CacheUpdater(Dictionary<TKey, TObject> data, Func<TObject, TKey>? keySele
 
         public void AddOrUpdate(IEnumerable<TObject> items)
         {
-            if (items is null)
-            {
-                throw new ArgumentNullException(nameof(items));
-            }
-
-            if (_keySelector is null)
-            {
-                throw new KeySelectorException("A key selector must be specified");
-            }
+            if (items is null) throw new ArgumentNullException(nameof(items));
+            if (_keySelector is null) throw new KeySelectorException("A key selector must be specified");
 
             if (items is IList<TObject> list)
             {
@@ -71,6 +64,42 @@ public void AddOrUpdate(IEnumerable<TObject> items)
             }
         }
 
+        public void AddOrUpdate(IEnumerable<TObject> items, IEqualityComparer<TObject> comparer)
+        {
+            if (items is null) throw new ArgumentNullException(nameof(items));
+            if (comparer is null) throw new ArgumentNullException(nameof(comparer));
+            if (_keySelector is null) throw new KeySelectorException("A key selector must be specified");
+
+            void AddOrUpdateImpl(TObject item)
+            {
+                var key = _keySelector!(item);
+                var oldItem = _cache.Lookup(key);
+
+                if (oldItem.HasValue)
+                {
+                    if (comparer.Equals(oldItem.Value, item)) return;
+
+                    _cache.AddOrUpdate(item, key);
+                }
+                else
+                {
+                    _cache.AddOrUpdate(item, key);
+                }
+            }
+
+            if (items is IList<TObject> list)
+            {
+                // zero allocation enumerator
+                foreach (var item in EnumerableIList.Create(list))
+                    AddOrUpdateImpl(item);
+            }
+            else
+            {
+                foreach (var item in items)
+                    AddOrUpdateImpl(item);
+            }
+        }
+
         public void AddOrUpdate(TObject item)
         {
             if (_keySelector is null)
@@ -395,4 +424,4 @@ public void Update(IChangeSet<TObject, TKey> changes)
             _cache.Clone(changes);
         }
     }
-}
+}
diff --git a/src/DynamicData/Cache/ObservableCacheEx.cs b/src/DynamicData/Cache/ObservableCacheEx.cs
@@ -148,6 +148,28 @@ public static void AddOrUpdate<TObject, TKey>(this ISourceCache<TObject, TKey> s
             source.Edit(updater => updater.AddOrUpdate(items));
         }
 
+        /// <summary>
+        /// <summary>
+        /// Adds or updates the cache with the specified items.
+        /// </summary>
+        /// </summary>
+        /// <typeparam name="TObject">The type of the object.</typeparam>
+        /// <typeparam name="TKey">The type of the key.</typeparam>
+        /// <param name="source">The source.</param>
+        /// <param name="items">The items.</param>
+        /// <param name="equalityComparer">The equality comparer used to determine whether a new item is the same as an existing cached item.</param>
+        /// <exception cref="System.ArgumentNullException">source.</exception>
+        public static void AddOrUpdate<TObject, TKey>(this ISourceCache<TObject, TKey> source, IEnumerable<TObject> items, IEqualityComparer<TObject> equalityComparer)
+            where TKey : notnull
+        {
+            if (source is null)
+            {
+                throw new ArgumentNullException(nameof(source));
+            }
+
+            source.Edit(updater => updater.AddOrUpdate(items, equalityComparer));
+        }
+
         /// <summary>
         /// Removes the specified key from the cache.
         /// If the item is not contained in the cache then the operation does nothing.
@@ -5648,4 +5670,4 @@ private static IObservable<bool> TrueFor<TObject, TKey, TValue>(this IObservable
             return new TrueFor<TObject, TKey, TValue>(source, observableSelector, collectionMatcher).Run();
         }
     }
-}
+}