string LoadCommand::Undo ( )
{
// If we were able to Execute this LOAD command one, we should
// be able to undo it whithout trouble.
// But just in case we apply the same safety mechanism.
// We must execute succesfully *all* commands, otherwise we just
// cancel the whole thing
string status = STATUS_OK;
while ( commandsDone.size( ) > 0 && status == STATUS_OK )
{
Command * currentCommand = commandsDone.top( );
if ( currentCommand->IsHistorizable( ) )
{
( (HistorizableCommand *) currentCommand )->Undo( );
}
// We consider all OK statuses to be equivalent
if ( status == STATUS_OK_SILENT || status == STATUS_OK )
{
status = STATUS_OK;
commandsDone.pop( );
commandsToDo.push( currentCommand );
}
}
// If we see as much as one error, we need to undo everything
if ( status == STATUS_ERROR )
{
cancelEverything( false );
}
return status;
}
void LoadCommand::cancelEverything ( bool undo )
{
// We were Executing commands but something failed,
// so now we undo everything.
if ( undo )
{
while ( commandsDone.size( ) > 0 )
{
Command * currentCommand = commandsDone.top( );
if ( currentCommand->IsHistorizable( ) )
{
( (HistorizableCommand *) currentCommand )->Undo( );
}
commandsDone.pop( );
commandsToDo.push( currentCommand );
}
}
// We were Undoing commands but something failed,
// so now we redo everything we had undone
else
{
while ( commandsToDo.size( ) > 0 )
{
Command * currentCommand = commandsToDo.top( );
currentCommand->Execute( );
commandsToDo.pop( );
commandsDone.push( currentCommand );
}
}
}
