Keyword mapping refactoring

Src/Data/Myc.Data.Keyword.pas

@@ -96,6 +96,19 @@ type
         class function Intern(const AFields: TArray<TPair<IKeyword, T>>): IKeywordMapping<T>; static;
     end;
 
+    TKeywordMapping<T> = class(TInterfacedObject, IKeywordMapping<T>)
+    private
+        FFields: TArray<TPair<IKeyword, T>>;
+
+        // IKeywordMapping implementation
+        function GetItems(Idx: Integer): TPair<IKeyword, T>;
+        function GetFields(const Key: IKeyword): T;
+        function GetCount: Integer;
+    public
+        constructor Create(const AFields: TArray<TPair<IKeyword, T>>);
+        function IndexOf(const Key: IKeyword): Integer;
+    end;
+
 implementation
 
 { TKeywordRegistry.TKeyword }
@@ -280,4 +293,49 @@ begin
     end;
 end;
 
+{ TKeywordMapping }
+
+constructor TKeywordMapping<T>.Create(const AFields: TArray<TPair<IKeyword, T>>);
+begin
+    inherited Create;
+    FFields := AFields;
+end;
+
+function TKeywordMapping<T>.GetCount: Integer;
+begin
+    Result := Length(FFields);
+end;
+
+function TKeywordMapping<T>.GetFields(const Key: IKeyword): T;
+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 TKeywordMapping<T>.GetItems(Idx: Integer): TPair<IKeyword, T>;
+begin
+    Result := FFields[Idx];
+end;
+
+function TKeywordMapping<T>.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 i := 0 to High(FFields) do
+    begin
+        if FFields[i].Key.Idx = Key.Idx then
+        begin
+            Result := i;
+            exit;
+        end;
+    end;
+    Result := -1;
+end;
+
 end.