Keyword mapping refactoring

Src/Data/Myc.Data.Records.pas

@@ -3,6 +3,7 @@ unit Myc.Data.Records;
 interface
 
 uses
+    System.SysUtils,
     System.Generics.Collections,
     Myc.Data.Keyword,
     Myc.Data.Value;
@@ -12,7 +13,11 @@ type
     TDynamicRecord = class(TInterfacedObject, IKeywordMapping<TDataValue>)
     private
         FFields: TArray<TPair<IKeyword, TDataValue>>;
-        function GetFields: TArray<TPair<IKeyword, TDataValue>>;
+
+        // IKeywordMapping implementation
+        function GetItems(Idx: Integer): TPair<IKeyword, TDataValue>;
+        function GetFields(const Key: IKeyword): TDataValue;
+        function GetCount: Integer;
     public
         constructor Create(const AFields: TArray<TPair<IKeyword, TDataValue>>);
         function IndexOf(const Key: IKeyword): Integer;
@@ -28,19 +33,39 @@ begin
     FFields := AFields;
 end;
 
-function TDynamicRecord.GetFields: TArray<TPair<IKeyword, TDataValue>>;
+function TDynamicRecord.GetCount: Integer;
 begin
-    Result := FFields;
+    Result := Length(FFields);
+end;
+
+function TDynamicRecord.GetFields(const Key: IKeyword): TDataValue;
+var
+    idx: Integer;
+begin
+    idx := IndexOf(Key);
+    if idx < 0 then
+        raise EArgumentException.CreateFmt('Field "%s" not found in dynamic record.', [Key.Name]);
+    Result := FFields[idx].Value;
+end;
+
+function TDynamicRecord.GetItems(Idx: Integer): TPair<IKeyword, TDataValue>;
+begin
+    Result := FFields[Idx];
 end;
 
 function TDynamicRecord.IndexOf(const Key: IKeyword): Integer;
+var
+    i: Integer;
 begin
     // Linear search (O(n)). Fast enough for typical records.
     // Keyword comparison is integer-based (Idx), so this is efficient.
-    for Result := 0 to High(FFields) do
+    for i := 0 to High(FFields) do
     begin
-        if FFields[Result].Key.Idx = Key.Idx then
+        if FFields[i].Key.Idx = Key.Idx then
+        begin
+            Result := i;
             exit;
+        end;
     end;
     Result := -1;
 end;