Entry

        pub const Entry = struct {
            /// The associated key for this entry.
            key: Key,
            /// A reference to the treap this entry is apart of.
            treap: *Self,
            /// The current node at this entry.
            node: ?*Node,
            /// The current state of the entry.
            context: union(enum) {
                /// A find() was called for this entry and the position in the treap is known.
                inserted_under: ?*Node,
                /// The entry's node was removed from the treap and a lookup must occur again for modification.
                removed,
            },

            /// Update's the Node at this Entry in the treap with the new node (null for deleting). `new_node`
            /// can have `undefind` content because the value will be initialized internally.
            pub fn set(self: *Entry, new_node: ?*Node) void {
                // Update the entry's node reference after updating the treap below.
                defer self.node = new_node;

                if (self.node) |old| {
                    if (new_node) |new| {
                        self.treap.replace(old, new);
                        return;
                    }

                    self.treap.remove(old);
                    self.context = .removed;
                    return;
                }

                if (new_node) |new| {
                    // A previous treap.remove() could have rebalanced the nodes
                    // so when inserting after a removal, we have to re-lookup the parent again.
                    // This lookup shouldn't find a node because we're yet to insert it..
                    var parent: ?*Node = undefined;
                    switch (self.context) {
                        .inserted_under => |p| parent = p,
                        .removed => assert(self.treap.find(self.key, &parent) == null),
                    }

                    self.treap.insert(self.key, parent, new);
                    self.context = .{ .inserted_under = parent };
                }
            }
        }