DataSeries.Copy

Src/Myc.Trade.DataPoint.pas

@@ -23,6 +23,7 @@ type
         function GetCount: Int64;
         function GetItems(Idx: Int64): TDataPoint<T>;
         function GetTotalCount: Int64;
+        function Copy: IDataSeries<T>;
         property Count: Int64 read GetCount;
         // Accesses data points by their logical index.
         // Index 0 is the newest element, Index (Count - 1) is the oldest.
@@ -40,18 +41,15 @@ type
     // Interface Helper for IDataSeries<T>.
     // Provides a safe, value-type-like wrapper around the interface.
     TDataSeries<T> = record
-    strict private
-        class var
-            FNull: IDataSeries<T>;
     private
         FDataSeries: IDataSeries<T>;
         FMaxLookback: Int64;
-        class constructor CreateClass;
         function GetCount: Int64;
         function GetItems(Idx: Int64): TDataPoint<T>;
         function GetData(Idx: Int64): T;
         function GetTime(Idx: Int64): TDateTime;
         function GetMaxLookback: Int64;
+        class function GetNull: IDataSeries<T>; static;
         function GetTotalCount: Int64;
     public
         constructor Create(ADataSeries: IDataSeries<T>);
@@ -64,13 +62,16 @@ type
 
         class function CreateArray(MaxLookback: Int64): IDataArray<T>; static;
 
+        // Create a guaranteed immutable version of the given series.
+        function Copy: TDataSeries<T>;
+
         // Searches for a data point by its timestamp.
         // Returns the logical index of the matching item.
         // If no exact match, returns the index of the item immediately preceding the timestamp.
         // Returns -1 if the timestamp is before the oldest item in the series.
         function IndexOf(TimeStamp: TDateTime): Int64;
 
-        class property Null: IDataSeries<T> read FNull;
+        class property Null: IDataSeries<T> read GetNull;
         property Count: Int64 read GetCount;
         property Items[Idx: Int64]: TDataPoint<T> read GetItems; default;
         property Data[Idx: Int64]: T read GetData;
@@ -100,19 +101,17 @@ begin
     Data := AData;
 end;
 
-{ TDataSeries<T> Interface Helper }
-
-class constructor TDataSeries<T>.CreateClass;
-begin
-    FNull := TNullDataSeries<T>.Create;
-end;
-
 constructor TDataSeries<T>.Create(ADataSeries: IDataSeries<T>);
 begin
     if Assigned(ADataSeries) then
         FDataSeries := ADataSeries
     else
-        FDataSeries := FNull;
+        FDataSeries := Null;
+end;
+
+function TDataSeries<T>.Copy: TDataSeries<T>;
+begin
+    Result := FDataSeries.Copy;
 end;
 
 class function TDataSeries<T>.CreateArray(MaxLookback: Int64): IDataArray<T>;
@@ -127,7 +126,7 @@ end;
 
 class operator TDataSeries<T>.Initialize(out Dest: TDataSeries<T>);
 begin
-    Dest.FDataSeries := FNull;
+    Dest.FDataSeries := Null;
 end;
 
 class operator TDataSeries<T>.Implicit(const A: TDataSeries<T>): IDataSeries<T>;
@@ -165,6 +164,11 @@ begin
     Result := FMaxLookback;
 end;
 
+class function TDataSeries<T>.GetNull: IDataSeries<T>;
+begin
+    Result := TNullDataSeries<T>.Null;
+end;
+
 function TDataSeries<T>.GetTotalCount: Int64;
 begin
     Result := FDataSeries.GetTotalCount;