private T?GetFirstDescendantInternal <T>(Func <Fb2Node, bool>?predicate = null)
where T : Fb2Node
{
if (IsEmpty)
{
return(null);
}
if (predicate == null)
{
predicate = PredicateResolver.GetPredicate <T>();
}
for (int i = 0; i < content.Count; i++)
{
var element = content[i];
if (predicate(element))
{
return((T)element);
}
if (element is Fb2Container containerElement)
{
var desc = containerElement.GetFirstDescendantInternal <T>(predicate);
if (desc != null)
{
return(desc);
}
}
}
return(null);
}
/// <summary>
/// Gets children of element by given node type (Fb2Node-based nodes).
/// </summary>
/// <typeparam name="T">Node type to select elements by.</typeparam>
/// <returns>List of found child elements, if any.</returns>
public IEnumerable <T> GetChildren <T>() where T : Fb2Node
{
if (IsEmpty)
{
return(Enumerable.Empty <T>());
}
var predicate = PredicateResolver.GetPredicate <T>();
var result = content.Where(predicate);
return(result.Any() ? result.Cast <T>() : Enumerable.Empty <T>());
}
/// <summary>
/// Gets first matching child of element by given node type (Fb2Node-based nodes).
/// </summary>
/// <param name="name">Node type to select child element by.</param>
/// <returns>First matched child node</returns>
public T?GetFirstChild <T>() where T : Fb2Node
{
if (IsEmpty)
{
return(null);
}
var predicate = PredicateResolver.GetPredicate <T>();
var result = content.FirstOrDefault(predicate);
if (result == null)
{
return(null);
}
return(result as T);
}
private IEnumerable <T> GetDescendantsInternal <T>(Func <Fb2Node, bool>?predicate = null)
where T : Fb2Node
{
if (IsEmpty)
{
return(Enumerable.Empty <T>());
}
var result = new List <Fb2Node>();
if (predicate == null)
{
predicate = PredicateResolver.GetPredicate <T>();
}
for (int i = 0; i < content.Count; i++)
{
var element = content[i];
if (predicate(element))
{
result.Add(element);
}
if (element is Fb2Container containerElement)
{
var desc = containerElement.GetDescendantsInternal <T>(predicate);
if (desc.Any())
{
result.AddRange(desc);
}
}
}
return(result.Cast <T>());
}