T PopBlock <T>() where T : BlockContainerNode
{
if (stack.IsEmpty())
{
AddError(true, "No {0} has been opened".FormatWith(BlockContainerNode.UserString(typeof(T))));
return(null);
}
BlockContainerNode n = stack.Pop();
if (n == null || !(n is T))
{
AddError(true, "Unexpected '{0}'".FormatWith(BlockContainerNode.UserString(n?.GetType())));
return(null);
}
variables = variables.Previous;
return((T)n);
}
T PeekBlock <T>() where T : BlockContainerNode
{
if (stack.IsEmpty())
{
AddError(true, "No {0} has been opened".FormatWith(BlockContainerNode.UserString(typeof(T))));
return(null);
}
BlockContainerNode n = stack.Peek();
if (n == null || !(n is T))
{
AddError(true, "Unexpected '{0}'".FormatWith(BlockContainerNode.UserString(n?.GetType())));
return(null);
}
variables = variables.Previous;
variables = new ScopedDictionary <string, ValueProviderBase>(variables);
return((T)n);
}