/// <summary>
/// Raise the event.
/// </summary>
/// <param name="expression">The <see cref="Expression"/> used.</param>
public void OnExecuteEnumerableCalled(Expression expression)
{
if (Parent != null)
{
Parent.OnExecuteEnumerableCalled(expression);
return;
}
QueryExecuted?.Invoke(this, new QuerySnapshotEventArgs(expression));
}
public void Back()
{
if (_historyHead <= 0)
{
return;
}
--_historyHead;
QueryExecuted?.Invoke(this, new QueryEventArgs(Current));
}
public void Forward()
{
if (_historyHead >= _history.Count - 1)
{
return;
}
++_historyHead;
QueryExecuted?.Invoke(this, new QueryEventArgs(Current));
}
public bool ExecuteQuery(IExecutableQuery query)
{
if (query == null)
{
throw new ArgumentNullException(nameof(query));
}
// trigger the BeforeQueryExecuted event and potentially cancel the operation
var args = new BeforeQueryExecutedEventArgs(query);
BeforeQueryExecuted?.Invoke(this, args);
if (args.IsCanceled)
{
return(false);
}
// only modify the history if the queries differ
if (Current == null ||
StringComparer.CurrentCultureIgnoreCase.Compare(query.Text, Current.Text) != 0)
{
// remove all entries in history after _historyHead
var index = _history.Count - 1;
while (index > _historyHead)
{
_history.RemoveAt(index--);
}
// add a new query to history and make it the current query
_history.Add(query);
++_historyHead;
Trace.Assert(_historyHead == _history.Count - 1);
}
// trigger query executed event
QueryExecuted?.Invoke(this, new QueryEventArgs(query));
return(true);
}
