Refacoring data pipeline

Src/Myc.Data.Records.pas

@@ -4,7 +4,8 @@ interface
 
 uses
     System.SysUtils,
-    System.TypInfo;
+    System.TypInfo,
+    Myc.Data.Pipeline;
 
 type
     TDataRecord = record
@@ -110,6 +111,40 @@ type
         property Layout: TLayout read FLayout;
     end;
 
+    TDataRecordLayoutHelper = record helper for TDataRecord.TLayout
+        function FieldAsRecord<T>(const Name: String): TConverter<T, TDataRecord>;
+        function FieldOfRecord<T>(const Name: String): TConverter<TDataRecord, T>;
+    end;
+
+type
+    TRecordMapping = record
+        Layout: TDataRecord.TLayout;
+        Fields: array of record
+        FromField, ToField: String
+        end;
+    end;
+
+    // Factory for creating specific converter instances.
+    TRecordConverter = record
+        class function DataMapping(
+            const Inputs: TArray<TRecordMapping>;
+            const Output: TDataRecord.TLayout
+        ): TConverter<TArray<TDataRecord>, TDataRecord>; static;
+
+        class function JoinRecords(
+            const TargetLayout: TDataRecord.TLayout;
+            const Mapping: TArray<TRecordMapping>;
+            const Producers: TArray<TProducer<TDataRecord>>
+        ): TConverter<TArray<TDataRecord>, TDataRecord>; static;
+    end;
+
+    TDataRecordHelper = record helper for TArray<TProducer<TDataRecord>>
+        function JoinRecords(
+            const TargetLayout: TDataRecord.TLayout;
+            const Mapping: TArray<TRecordMapping>
+        ): TProducer<TDataRecord>; experimental;
+    end;
+
 implementation
 
 uses
@@ -569,4 +604,81 @@ begin
     Result := not (A = B);
 end;
 
+function TDataRecordLayoutHelper.FieldAsRecord<T>(const Name: String): TConverter<T, TDataRecord>;
+begin
+    var layout := Self;
+    var idx := IndexOf(Name);
+    Result :=
+        TConverter<T, TDataRecord>.CreateConverter(
+            function(const Value: T): TDataRecord
+            begin
+                Result := TDataRecord.Create(layout);
+                Result.SetValue(idx, Value);
+            end
+        );
+end;
+
+function TDataRecordLayoutHelper.FieldOfRecord<T>(const Name: String): TConverter<TDataRecord, T>;
+begin
+    var idx := IndexOf(Name);
+    Result := TConverter<TDataRecord, T>.CreateConverter(function(const Value: TDataRecord): T begin Value.GetValue(idx, Result); end);
+end;
+
+class function TRecordConverter.DataMapping(
+    const Inputs: TArray<TRecordMapping>;
+    const Output: TDataRecord.TLayout
+): TConverter<TArray<TDataRecord>, TDataRecord>;
+var
+    Idxs: array of array of record
+    FromIdx, ToIdx: Integer
+    end;
+begin
+    SetLength(Idxs, Length(Inputs));
+    for var i := 0 to High(Idxs) do
+    begin
+        SetLength(Idxs[i], Length(Inputs[i].Fields));
+        for var j := 0 to High(Idxs[i]) do
+        begin
+            Idxs[i][j].FromIdx := Inputs[i].Layout.IndexOf(Inputs[i].Fields[j].FromField);
+            Idxs[i][j].ToIdx := Output.IndexOf(Inputs[i].Fields[j].ToField);
+        end;
+    end;
+
+    Result :=
+        TConverter<TArray<TDataRecord>, TDataRecord>.CreateConverter(
+            function(const Inputs: TArray<TDataRecord>): TDataRecord
+            begin
+                Result := TDataRecord.Create(Output);
+                for var i := 0 to High(Idxs) do
+                    for var j := 0 to High(Idxs[i]) do
+                        Result.CopyValue(Inputs[i], Idxs[i][j].FromIdx, Idxs[i][j].ToIdx);
+            end
+        );
+end;
+
+class function TRecordConverter.JoinRecords(
+    const TargetLayout: TDataRecord.TLayout;
+    const Mapping: TArray<TRecordMapping>;
+    const Producers: TArray<TProducer<TDataRecord>>
+): TConverter<TArray<TDataRecord>, TDataRecord>;
+begin
+    var RecProvider := TConverter.Join<TDataRecord>(jmAll, Producers);
+
+    Result := TRecordConverter.DataMapping(Mapping, TargetLayout);
+
+    RecProvider.Chain(Result.Consumer);
+end;
+
+function TDataRecordHelper.JoinRecords(
+    const TargetLayout: TDataRecord.TLayout;
+    const Mapping: TArray<TRecordMapping>
+): TProducer<TDataRecord>;
+begin
+    var map := TRecordConverter.DataMapping(Mapping, TargetLayout);
+
+    TConverter.Join<TDataRecord>(jmAll, Self).Chain(map.Consumer);
+
+    Result := map.Producer;
+end;
+
 end.