Add capabilities for Summarize()

src/libraries/Microsoft.PowerFx.Core/Entities/External/TableDelegationInfo.cs

@@ -23,6 +23,9 @@ public abstract class TableDelegationInfo
         // Used to indicate whether this table has selectable columns
         public SelectionRestrictions SelectionRestriction { get; init; }
 
+        [Obsolete("preview")]
+        public SummarizeCapabilities SummarizeCapabilities { get; init; }
+
         // Defines ungroupable columns
         public GroupRestrictions GroupRestriction { get; init; }
 
@@ -266,6 +269,35 @@ public SelectionRestrictions()
         }
     }
 
+    [Obsolete("preview")]
+    public class SummarizeCapabilities
+    {
+        public virtual bool IsSummarizableProperty(string propertyName)
+        {
+            return false;
+        }
+
+        public virtual bool IsSummarizableMethod(SummarizeMethod method)
+        {
+            return false;
+        }
+
+        public SummarizeCapabilities()
+        {
+        }
+    }
+
+    [Obsolete("preview")]
+    public enum SummarizeMethod
+    {
+        None,
+        Sum,
+        Average,
+        Min,
+        Max,
+        Count,
+    }
+
     public sealed class FilterRestrictions
     {
         // List of required properties

src/libraries/Microsoft.PowerFx.Core/Public/Values/DelegationParameters.cs

@@ -73,6 +73,9 @@ public enum DelegationParameterFeatures
         // $apply
         Apply = 1 << 4,
 
+        // $apply = groupby((field1, ..), field with sum as TotalSum)
+        ApplyGroupBy = 1 << 5,
+
         /*
           To be implemented later when needed
 

src/tests/Microsoft.PowerFx.Core.Tests.Shared/PublicSurfaceTests.cs

@@ -202,6 +202,8 @@ public void PublicSurface_Tests()
                 "Microsoft.PowerFx.Core.Entities.IRefreshable",                
                 "Microsoft.PowerFx.Core.Entities.SelectionRestrictions",
                 "Microsoft.PowerFx.Core.Entities.SortRestrictions",
+                "Microsoft.PowerFx.Core.Entities.SummarizeCapabilities",
+                "Microsoft.PowerFx.Core.Entities.SummarizeMethod",
                 "Microsoft.PowerFx.Core.Entities.TableDelegationInfo",
                 "Microsoft.PowerFx.Core.Functions.Delegation.DelegationOperator",
                 "Microsoft.PowerFx.Core.Localization.ErrorResourceKey",