From f377d044d6f0c321a01789f55d4a024bfdb8129e Mon Sep 17 00:00:00 2001
From: John Gross <mindstorms11@cox.net>
Date: Thu, 21 Sep 2017 20:15:18 -0700
Subject: [PATCH] Observable type improvements

---
 Torch/Collections/ObservableDictionary.cs | 147 +++++++++++++++++++---
 Torch/ViewModels/ViewModel.cs             |  11 ++
 2 files changed, 142 insertions(+), 16 deletions(-)

diff --git a/Torch/Collections/ObservableDictionary.cs b/Torch/Collections/ObservableDictionary.cs
index 2d3f955..68a4a33 100644
--- a/Torch/Collections/ObservableDictionary.cs
+++ b/Torch/Collections/ObservableDictionary.cs
@@ -1,8 +1,10 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.ComponentModel;
 using System.Linq;
+using System.Runtime.CompilerServices;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows.Threading;
@@ -10,28 +12,148 @@ using System.Windows.Threading;
 namespace Torch.Collections
 {
     [Serializable]
-    public class ObservableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, INotifyCollectionChanged, INotifyPropertyChanged
+    public class ObservableDictionary<TKey, TValue> : ViewModel, IDictionary<TKey, TValue>, INotifyCollectionChanged
     {
-        /// <inheritdoc />
-        public new void Add(TKey key, TValue value)
+        private IDictionary<TKey, TValue> _internalDict;
+
+        public ObservableDictionary()
         {
-            base.Add(key, value);
-            var kv = new KeyValuePair<TKey, TValue>(key, value);
-            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, kv));
+            _internalDict = new Dictionary<TKey, TValue>();
+        }
+
+        public ObservableDictionary(IDictionary<TKey, TValue> dictionary)
+        {
+            _internalDict = new Dictionary<TKey, TValue>(dictionary);
+        }
+
+        /// <summary>
+        /// Create a <see cref="ObservableDictionary{TKey,TValue}"/> using the given dictionary by reference. The original dictionary should not be used after calling this.
+        /// </summary>
+        public static ObservableDictionary<TKey, TValue> ByReference(IDictionary<TKey, TValue> dictionary)
+        {
+            return new ObservableDictionary<TKey, TValue>
+            {
+                _internalDict = dictionary
+            };
         }
 
         /// <inheritdoc />
-        public new bool Remove(TKey key)
+        public event NotifyCollectionChangedEventHandler CollectionChanged;
+
+        /// <inheritdoc />
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        /// <inheritdoc />
+        public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
         {
-            if (!ContainsKey(key))
+            return _internalDict.GetEnumerator();
+        }
+
+        /// <inheritdoc />
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return ((IEnumerable)_internalDict).GetEnumerator();
+        }
+
+        /// <inheritdoc />
+        public void Add(KeyValuePair<TKey, TValue> item)
+        {
+            Add(item.Key, item.Value);
+        }
+
+        /// <inheritdoc />
+        public bool Remove(KeyValuePair<TKey, TValue> item)
+        {
+            return Remove(item.Key);
+        }
+
+        /// <inheritdoc />
+        public void Clear()
+        {
+            _internalDict.Clear();
+            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+            OnPropertyChanged(nameof(Count));
+        }
+
+        /// <inheritdoc />
+        public bool Contains(KeyValuePair<TKey, TValue> item)
+        {
+            return _internalDict.Contains(item);
+        }
+
+        /// <inheritdoc />
+        public void CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex)
+        {
+            foreach (var kv in _internalDict)
+            {
+                array[arrayIndex] = kv;
+                arrayIndex++;
+            }
+        }
+
+        /// <inheritdoc />
+        public int Count => _internalDict.Count;
+
+        /// <inheritdoc />
+        public bool IsReadOnly => false;
+
+        /// <inheritdoc />
+        public bool ContainsKey(TKey key)
+        {
+            return _internalDict.ContainsKey(key);
+        }
+
+        /// <inheritdoc />
+        public void Add(TKey key, TValue value)
+        {
+            _internalDict.Add(key, value);
+            var kv = new KeyValuePair<TKey, TValue>(key, value);
+            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, kv));
+            OnPropertyChanged(nameof(Count));
+        }
+
+        /// <inheritdoc />
+        public bool Remove(TKey key)
+        {
+            if (!_internalDict.ContainsKey(key))
                 return false;
 
             var kv = new KeyValuePair<TKey, TValue>(key, this[key]);
-            base.Remove(key);
+            if (!_internalDict.Remove(key))
+                return false;
+
             OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, kv));
+            OnPropertyChanged(nameof(Count));
             return true;
         }
 
+        /// <inheritdoc />
+        public bool TryGetValue(TKey key, out TValue value)
+        {
+            return _internalDict.TryGetValue(key, out value);
+        }
+
+        /// <inheritdoc />
+        public TValue this[TKey key]
+        {
+            get => _internalDict[key];
+            set
+            {
+                var oldKv = new KeyValuePair<TKey, TValue>(key, _internalDict[key]);
+                var newKv = new KeyValuePair<TKey, TValue>(key, value);
+                _internalDict[key] = value;
+                OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, newKv, oldKv));
+            }
+
+
+        }
+
+        /// <inheritdoc />
+        public ICollection<TKey> Keys => _internalDict.Keys;
+
+        /// <inheritdoc />
+        public ICollection<TValue> Values => _internalDict.Values;
+
         private void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
         {
             NotifyCollectionChangedEventHandler collectionChanged = CollectionChanged;
@@ -52,12 +174,5 @@ namespace Torch.Collections
                     nh.Invoke(this, e);
                 }
         }
-
-
-        /// <inheritdoc />
-        public event NotifyCollectionChangedEventHandler CollectionChanged;
-
-        /// <inheritdoc />
-        public event PropertyChangedEventHandler PropertyChanged;
     }
 }
diff --git a/Torch/ViewModels/ViewModel.cs b/Torch/ViewModels/ViewModel.cs
index 010f34c..7233102 100644
--- a/Torch/ViewModels/ViewModel.cs
+++ b/Torch/ViewModels/ViewModel.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Linq;
+using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Text;
 using System.Threading.Tasks;
@@ -20,6 +21,16 @@ namespace Torch
             PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propName));
         }
 
+        protected virtual void SetValue<T>(ref T backingField, T value, [CallerMemberName] string propName = "")
+        {
+            if (backingField.Equals(value))
+                return;
+
+            backingField = value;
+            // ReSharper disable once ExplicitCallerInfoArgument
+            OnPropertyChanged(propName);
+        }
+
         /// <summary>
         /// Fires PropertyChanged for all properties.
         /// </summary>