Data Types

Src/Data/Myc.Data.Types.Text.pas

@@ -7,7 +7,7 @@ uses
     Myc.Data.Types;
 
 type
-    TImplDataTextType = class(TInterfacedObject, IDataType, IDataTextType)
+    TDataTextType = class(TInterfacedObject, IDataType, IDataTextType)
     strict private
         class var
             FSingleton: IDataTextType;
@@ -19,7 +19,10 @@ type
         class property Singleton: IDataTextType read FSingleton;
     end;
 
-    TImplDataTextValue = class(TInterfacedObject, IDataValue, IDataTextValue)
+implementation
+
+type
+    TDataTextValue = class(TInterfacedObject, IDataValue, IDataTextValue)
     private
         FValue: string;
         function GetDataType: IDataType;
@@ -29,51 +32,89 @@ type
         constructor Create(const AValue: string);
     end;
 
-implementation
+    // Singleton implementation for the empty string value.
+    TDataTextValueEmpty = class(TInterfacedObject, IDataValue, IDataTextValue)
+    strict private
+        class var
+            FSingleton: IDataTextValue;
+        class constructor CreateClass;
+    private
+        function GetDataType: IDataType;
+        function GetAsString: string;
+        function GetValue: string;
+    public
+        class property Singleton: IDataTextValue read FSingleton;
+    end;
 
-{ TImplDataTextType }
+{ TDataTextType }
 
-class constructor TImplDataTextType.CreateClass;
+class constructor TDataTextType.CreateClass;
 begin
-    FSingleton := TImplDataTextType.Create;
+    FSingleton := TDataTextType.Create;
 end;
 
-function TImplDataTextType.CreateValue(const AValue: string): IDataTextValue;
+function TDataTextType.CreateValue(const AValue: string): IDataTextValue;
 begin
-    Result := TImplDataTextValue.Create(AValue);
+    // Use the singleton for empty strings.
+    if (AValue = '') then
+        Result := TDataTextValueEmpty.Singleton
+    else
+        Result := TDataTextValue.Create(AValue);
 end;
 
-function TImplDataTextType.GetName: String;
+function TDataTextType.GetName: String;
 begin
     Result := 'Text';
 end;
 
-function TImplDataTextType.GetKind: TDataKind;
+function TDataTextType.GetKind: TDataKind;
 begin
     Result := dkText;
 end;
 
-{ TImplDataTextValue }
+{ TDataTextValue }
 
-constructor TImplDataTextValue.Create(const AValue: string);
+constructor TDataTextValue.Create(const AValue: string);
 begin
     inherited Create;
     FValue := AValue;
 end;
 
-function TImplDataTextValue.GetDataType: IDataType;
+function TDataTextValue.GetDataType: IDataType;
 begin
-    Result := TImplDataTextType.Singleton;
+    Result := TDataTextType.Singleton;
 end;
 
-function TImplDataTextValue.GetAsString: string;
+function TDataTextValue.GetAsString: string;
 begin
     Result := FValue;
 end;
 
-function TImplDataTextValue.GetValue: string;
+function TDataTextValue.GetValue: string;
 begin
     Result := FValue;
 end;
 
+{ TDataTextValueEmpty }
+
+class constructor TDataTextValueEmpty.CreateClass;
+begin
+    FSingleton := TDataTextValueEmpty.Create;
+end;
+
+function TDataTextValueEmpty.GetAsString: string;
+begin
+    Result := '';
+end;
+
+function TDataTextValueEmpty.GetDataType: IDataType;
+begin
+    Result := TDataTextType.Singleton;
+end;
+
+function TDataTextValueEmpty.GetValue: string;
+begin
+    Result := '';
+end;
+
 end.