Ast series indexer

Src/Data/Myc.Data.POD.pas

@@ -114,7 +114,14 @@ type
         constructor Create(const AName: String; AKind: TScalarKind);
     end;
 
-    TScalarRecordDefinition = TArray<TScalarRecordField>;
+    TScalarRecordDefinition = record
+    private
+        FFields: TArray<TScalarRecordField>;
+    public
+        constructor Create(const AFields: TArray<TScalarRecordField>);
+        function IndexOf(const Name: String): Integer;
+        property Fields: TArray<TScalarRecordField> read FFields;
+    end;
 
     // A record of scalar values, based on a definition.
     TScalarRecord = record
@@ -152,6 +159,20 @@ type
         FItems: TSeries<TScalarValue>;
     end;
 
+    TScalarMemberSeries = record
+    private
+        FDef: TScalarRecordDefinition;
+        FArray: TChunkArray<TScalarValue>;
+        FElement: Integer;
+        function GetCount: Int64; inline;
+        function GetItems(Idx: Integer): TScalarValue;
+    public
+        constructor Create(const ADef: TScalarRecordDefinition; const AArray: TChunkArray<TScalarValue>; AElement: Integer);
+        property Count: Int64 read GetCount;
+        property Element: Integer read FElement;
+        property Items[Idx: Integer]: TScalarValue read GetItems; default;
+    end;
+
     // A time series of scalar records, optimized for memory and access speed.
     TScalarRecordSeries = record
     private
@@ -163,6 +184,7 @@ type
     public
         constructor Create(const ADef: TScalarRecordDefinition);
         procedure Add(const Item: TScalarRecord; Lookback: Int64 = -1);
+        function CreateMemberSeries(const Field: String): TScalarMemberSeries;
         property Def: TScalarRecordDefinition read GetDef;
         property Items[Idx: Integer]: TScalarRecord read GetItems; default;
         property TotalCount: Int64 read FTotalCount;
@@ -384,7 +406,7 @@ end;
 
 constructor TScalarRecord.Create(const ADef: TScalarRecordDefinition; const AFields: TArray<TScalarValue>);
 begin
-    Assert(Length(ADef) = Length(AFields), 'Field definition and value count must match.');
+    Assert(Length(ADef.Fields) = Length(AFields), 'Field definition and value count must match.');
     FDef := ADef;
     FFields := AFields;
 end;
@@ -405,9 +427,9 @@ var
     fieldDef: TScalarRecordField;
 begin
     // Find the index of the field by name (case-insensitive)
-    for i := 0 to Length(FDef) - 1 do
+    for i := 0 to High(FDef.Fields) do
     begin
-        fieldDef := FDef[i];
+        fieldDef := FDef.Fields[i];
         if (CompareText(fieldDef.Name, Name) = 0) then
         begin
             // Found it. Construct the TScalar result from the kind and value.
@@ -445,7 +467,7 @@ end;
 
 constructor TScalarRecordSeries.Create(const ADef: TScalarRecordDefinition);
 begin
-    Assert(Length(ADef) > 0);
+    Assert(Length(ADef.Fields) > 0);
     FDef := ADef;
     FArray := Default(TChunkArray<TScalarValue>);
     FTotalCount := 0;
@@ -453,10 +475,19 @@ end;
 
 procedure TScalarRecordSeries.Add(const Item: TScalarRecord; Lookback: Int64 = -1);
 begin
-    FArray.Add(Item.Fields, Length(FDef) * Lookback);
+    FArray.Add(Item.Fields, Length(FDef.Fields) * Lookback);
     inc(FTotalCount);
 end;
 
+function TScalarRecordSeries.CreateMemberSeries(const Field: String): TScalarMemberSeries;
+begin
+    var elem := FDef.IndexOf(Field);
+    if elem < 0 then
+        raise EArgumentException.CreateFmt('Field "%s" not found in record definition.', [Field]);
+
+    Result := TScalarMemberSeries.Create(FDef, FArray, elem);
+end;
+
 function TScalarRecordSeries.GetDef: TScalarRecordDefinition;
 begin
     Result := FDef;
@@ -467,12 +498,53 @@ var
     values: TArray<TScalarValue>;
     fieldCount: Integer;
 begin
-    fieldCount := Length(FDef);
+    fieldCount := Length(FDef.Fields);
     SetLength(values, fieldCount);
     Move(FArray.ItemRef[(FArray.Count - fieldCount) - (Idx * fieldCount)]^, values[0], sizeof(TScalarValue) * fieldCount);
     Result.Create(FDef, values);
 end;
 
+constructor TScalarMemberSeries.Create(const ADef: TScalarRecordDefinition; const AArray: TChunkArray<TScalarValue>; AElement: Integer);
+begin
+    FDef := ADef;
+    FArray := AArray;
+    FElement := AElement;
+end;
+
+function TScalarMemberSeries.GetCount: Int64;
+begin
+    Result := FArray.Count;
+end;
+
+function TScalarMemberSeries.GetItems(Idx: Integer): TScalarValue;
+var
+    values: TArray<TScalarValue>;
+    fieldCount: Integer;
+begin
+    fieldCount := Length(FDef.Fields);
+    SetLength(values, fieldCount);
+    Result := FArray.ItemRef[(FArray.Count - fieldCount) - (Idx * fieldCount)]^;
+end;
+
+constructor TScalarRecordDefinition.Create(const AFields: TArray<TScalarRecordField>);
+begin
+    FFields := AFields;
+end;
+
+function TScalarRecordDefinition.IndexOf(const Name: String): Integer;
+var
+    i: Integer;
+    fieldDef: TScalarRecordField;
+begin
+    // Find the index of the field by name (case-insensitive)
+    for i := 0 to High(FFields) do
+        if (CompareText(FFields[i].Name, Name) = 0) then
+            exit(i);
+
+    // If we get here, the field was not found.
+    raise EArgumentException.CreateFmt('Field "%s" not found in record definition.', [Name]);
+end;
+
 initialization
     Assert(sizeof(TScalarValue) = 8);