feature request: remove_children and detach_children

[PoiScript]

When dealing with the tree structure, sometimes we want to remove the all children nodes of a specific node but keeping the node itself. For example, removing anything between tags <p> and </p>.

Here is a snippet demonstrating how to implement detach_children with indextree:

fn detach_children<T>(self, arena: &mut Arena<T>) {
    for child in self.children(arena) {
        let node = arena[child];
        node.parent = None;
        node.next_sibling = None;
        node.previous_sibling = None;
    }
    
    let node = arena[self];
    node.first_child = None;
    node.last_child = None;
}

I haven't tried it yet, so it may not be compiled.

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[lo48576]

indextree allows toplevel nodes to have siblings, so next_sibling and previous_sibling of children can be left unmodified.

[PoiScript]

@lo48576 Then the following two codes will behave differently:

fn detach_children<T>(self, arena: &mut Arena<T>) {
    for child in self.children(arena) {
        let node = arena[child];
        node.parent = None;
    }
    
    let node = arena[self];
    node.first_child = None;
    node.last_child = None;
}

for child in self.children(arena) {
    child.detach(arena);
}

I don't know it is needed to keep the relation between detached children. But at least it should be mentioned on document in order not to get the user confused.

[lo48576]

Yes, I think the name detach_children() has a little ambiguity (which it means), and it should be explicitly documented (or better name should be chosen).

[GopherJ]

I also need remove_children method to make a graph.