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program tforin9;
// Test interface with 'enumerator MoveNext', 'enumerator Current' directives
{$mode objfpc}{$H+}
{$APPTYPE CONSOLE}
type
{ IMyIterator }
IMyIterator = interface
function GetValue: TObject;
function StepForward: Boolean; enumerator MoveNext;
property Value: TObject read GetValue; enumerator Current;
end;
{ TMyListEnumerator }
TMyListEnumerator = class(TInterfacedObject, IMyIterator)
private
FValue: Pointer;
function GetValue: TObject;
public
function StepForward: Boolean;
property Value: TObject read GetValue;
end;
TMyList = class
public
function GetIterator: IMyIterator;
end;
operator Enumerator(AList: TMyList): IMyIterator;
begin
Result := AList.GetIterator;
end;
{ TMyListEnumerator }
function TMyListEnumerator.GetValue: TObject;
begin
Result := TObject(FValue);
end;
function TMyListEnumerator.StepForward: Boolean;
begin
inc(PByte(FValue));
Result := FValue <= Pointer(3);
end;
{ TMyList }
function TMyList.GetIterator: IMyIterator;
begin
Result := TMyListEnumerator.Create;
end;
var
List: TMyList;
i: TObject;
begin
List := TMyList.Create;
for i in List do
WriteLn(PtrInt(i));
List.Free;
end.
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