This is not possible at the moment. What you want is called non-lexical borrows and it is yet to be implemented in Rust. Meanwhile, you should use Entry
API to work with maps – in most cases it should be sufficient. In this particular case I’m not sure if entries are applicable, but you can always do something like
let mut result = None;
if let Some(&Node::LeafNode(ref leaf_node)) = self.pages.get(&page) {
let mut leaf_node = leaf_node.clone();
// ...
result = Some((leaf_page, leaf_node));
}
if let Some((leaf_page, leaf_node)) = result {
self.pages.insert(leaf_page, leaf_node);
}
It is difficult to make the code above entirely correct given that you didn’t provide definitions of Node
and self.pages
, but it should be approximately right. Naturally, it would work only if leaf_page
and leaf_node
do not contain references to self.pages
or self
, otherwise you won’t be able to access self.pages
.