Code-Calculated View Fields

Source/Assets/MarkLight/Source/Plugins/AutoSubscription.cs

@@ -0,0 +1,59 @@
+using UnityEngine;
+using System.Collections.Generic;
+
+namespace MarkLight
+{
+    public static class AutoSubscription
+    {
+        static Stack<IAutoSubscriber> AutoSubscriberQueue = new Stack<IAutoSubscriber>();
+        static HashSet<IAutoSubscriber> AutoSubscribers = new HashSet<IAutoSubscriber>();
+
+        public static int ActiveAutoSubscriberCount { get { return AutoSubscriberQueue.Count; } }
+
+        public static void StartSubscription(IAutoSubscriber subscriber)
+        {
+            if (subscriber == null)
+                throw new System.ArgumentNullException("subscriber");
+            if (AutoSubscribers.Contains(subscriber))
+                throw new System.InvalidOperationException("Recursive calculation detected");
+
+            AutoSubscriberQueue.Push(subscriber);
+            AutoSubscribers.Add(subscriber);
+        }
+
+        public static void EndSubscription(IAutoSubscriber subscriber)
+        {
+            if (subscriber == null)
+                throw new System.ArgumentNullException("subscriber");
+            if (AutoSubscriberQueue.Count == 0)
+                throw new System.InvalidOperationException("There are no active IAutoSubscribers");
+            if (!AutoSubscribers.Contains(subscriber))
+                throw new System.InvalidOperationException("EndSubscription called on a subscriber without StartSubscription");
+            if (AutoSubscriberQueue.Peek() != subscriber)
+                throw new System.InvalidOperationException("EndSubscription is being called for a subscriber that is not at the top of the stack");
+
+            AutoSubscribers.Remove(subscriber);
+            AutoSubscriberQueue.Pop();
+        }
+
+        public static void NotifyViewFieldWasAccessed(ViewFieldBase field)
+        {
+            if (AutoSubscriberQueue.Count == 0)
+                return;
+
+            IAutoSubscriber topmostSubscriber = AutoSubscriberQueue.Peek();
+            topmostSubscriber.ViewFieldWasAccessed(field);
+        }
+
+        public static void NotifyObservableListWasAccessed(IObservableList list)
+        {
+            if (AutoSubscriberQueue.Count == 0)
+                return;
+
+            IAutoSubscriber topmostSubscriber = AutoSubscriberQueue.Peek();
+            topmostSubscriber.ObservableListWasAccessed(list);
+        }
+
+
+    }
+}

Source/Assets/MarkLight/Source/Plugins/CalculatedViewField.cs

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+using System;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace MarkLight
+{
+    [Serializable]
+    public class CalculatedViewField<T> : ViewField<T>, IAutoSubscriber
+    {
+        bool IsCalculating;
+        bool CachedValueIsValid;
+        HashSet<ViewFieldBase> FieldsSubscribedTo = new HashSet<ViewFieldBase>();
+        HashSet<IObservableList> ObservableListsSubscribedTo = new HashSet<IObservableList>();
+        public System.Func<T> GetCalculatedValue;
+        public System.Action<T> UpdateSourceValuesFromValue;
+
+        public override T InternalValue
+        {
+            get
+            {
+                EnsureCachedValueIsUpToDate();
+                return base.InternalValue;
+            }
+
+            set
+            {
+                base.InternalValue = value;
+            }
+        }
+
+        public override T Value
+        {
+            get
+            {
+                EnsureCachedValueIsUpToDate();
+                return base.Value;
+            }
+
+            set
+            {
+                base.Value = value;
+            }
+        }
+
+        void EnsureCachedValueIsUpToDate()
+        {
+            if (!CachedValueIsValid)
+                UpdateCachedValue();
+        }
+
+        void UpdateCachedValue()
+        {
+            CachedValueIsValid = false;
+            if (GetCalculatedValue == null)
+                throw new System.InvalidOperationException("GetCalculatedValue has not been specifed");
+            T calculatedValue;
+            try
+            {
+                IsCalculating = true;
+                ClearChangeSubscriptions();
+                AutoSubscription.StartSubscription(this);
+                calculatedValue = GetCalculatedValue();
+            }
+            finally
+            {
+                IsCalculating = false;
+                AutoSubscription.EndSubscription(this);
+            }
+            CachedValueIsValid = true;
+            Value = calculatedValue;
+        }
+
+        void SetValue(T value)
+        {
+            if (UpdateSourceValuesFromValue == null)
+                return;
+            UpdateSourceValuesFromValue(value);
+            CachedValueIsValid = false;
+        }
+
+        void IAutoSubscriber.ViewFieldWasAccessed(ViewFieldBase viewField)
+        {
+            if (viewField != this && !FieldsSubscribedTo.Contains(viewField))
+            {
+                viewField.ValueSet += ViewField_ValueSet;
+                FieldsSubscribedTo.Add(viewField);
+            }
+        }
+
+        void IAutoSubscriber.ObservableListWasAccessed(IObservableList list)
+        {
+            if (!ObservableListsSubscribedTo.Contains(list))
+            {
+                list.ListChanged += List_ListChanged;
+                ObservableListsSubscribedTo.Add(list);
+            }
+        }
+
+        private void List_ListChanged(object sender, ListChangedEventArgs e)
+        {
+            CachedValueIsValid = false;
+            if (!IsCalculating)
+                UpdateCachedValue();
+        }
+
+        void ViewField_ValueSet(object sender, EventArgs e)
+        {
+            CachedValueIsValid = false;
+            if (!IsCalculating)
+                UpdateCachedValue();
+        }
+
+        void ClearChangeSubscriptions()
+        {
+            foreach (ViewFieldBase notifier in FieldsSubscribedTo)
+                notifier.ValueSet -= ViewField_ValueSet;
+            FieldsSubscribedTo.Clear();
+
+            foreach (IObservableList notifier in ObservableListsSubscribedTo)
+                notifier.ListChanged -= List_ListChanged;
+            ObservableListsSubscribedTo.Clear();
+        }
+    }
+
+    [Serializable]
+    public class _CalculatedString : CalculatedViewField<string> { }
+}

Source/Assets/MarkLight/Source/Plugins/IAutoSubscriber.cs

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+namespace MarkLight
+{
+    public interface IAutoSubscriber
+    {
+        void ViewFieldWasAccessed(ViewFieldBase viewField);
+        void ObservableListWasAccessed(IObservableList list);
+    }
+}