flange-flat-tree 0.2.2

A tree that can be expanded by attaching new values to the node without mutability of the old ones
Documentation 
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use super::subtree::subtree_impl::SubtreeImpl;
use crate::{navigator::Navigator, Tree};

use super::tree_data::TreeData;

pub struct MappedTree<A, B, M, TD>
where
    M: Fn(usize, A) -> B,
    TD: TreeData<Node = A>,
{
    mapf: M,
    base: TD,
}

impl<A, B, M, TD> MappedTree<A, B, M, TD>
where
    M: Fn(usize, A) -> B,
    TD: TreeData<Node = A>,
{
    pub fn new(base: TD, mapf: M) -> Self {
        MappedTree { mapf, base }
    }
}

impl<'a, A, B, M, TD> TreeData for &'a MappedTree<A, B, M, TD>
where
    M: Fn(usize, A) -> B,
    TD: TreeData<Node = A>,
{
    type Node = B;

    fn get(self, index: usize) -> Self::Node {
        (self.mapf)(index, self.base.get(index))
    }

    fn count(self) -> usize {
        self.base.count()
    }

    fn get_nav(&self) -> &Navigator {
        self.base.get_nav()
    }
}

impl<'a, A, B, M, TD> Tree<'a> for MappedTree<A, B, M, TD>
where
    A: 'a,
    B: 'a,
    M: Fn(usize, A) -> B + 'a,
    TD: TreeData<Node = A> + 'a,
{
    type Node = B;
    type SubtreeType = SubtreeImpl<&'a Self>;
    fn at_pos(&'a self, index: usize) -> Self::SubtreeType {
        SubtreeImpl::new(self, index)
    }

    fn get_nav(&self) -> &Navigator {
        self.base.get_nav()
    }
}

// impl<'a, T: Tree, Node: MappedTreeNode> TreeData for &'a MappedTree<T, Node>
// where
//     for<'b> &'b T: TreeData,
// {
//     type Node = Node;
//     fn get(&self, index: usize) -> Self::Node {
//         Node::create((&self.base).get(index), &self.data[index])
//     }

//     fn get_neighbors(&self, index: usize) -> &Neighbors<usize> {
//         (&self.base).get_neighbors(index)
//     }
// }