A tree CRDT for Yrs, a Rust implementation of Yjs, based on the algorithm described in Evan Wallace's article on CRDT Mutable Tree Hierarchies. Changes among clients are guaranteed to converge to a consistent state, and the tree ensures that conflicts and cycles are handled correctly.
Each node in the tree has an ID. The root node is always NodeId::Root; user-created nodes have IDs of the form NodeId::Id(String). Nodes can be accessed by their ID using the [Tree::get_node] method.
Each node can also store and retrieve arbitrary data associated with that node. See the [Node::set] and [Node::get]/[Node::get_as] methods for more information.
cargo add yrs_treeYou can find the complete documentation on Docs.rs.
Quick links:
When the underlying Yrs document is updated, the tree automatically updates its state in response. If the library detects that the Yrs document is malformed in a way that cannot be reconciled, it will mark the tree as "poisoned."
When a tree is poisoned, any operations on the tree that rely on the Yrs document will fail with a TreePoisoned error. Operations that only rely on the tree's cached state will continue to succeed, but will not reflect the latest state of the Yrs document.
use std::{error::Error, sync::Arc};use yrs_tree::{NodeApi,Tree,TreeEvent,TraversalOrder};fnmain() -> Result<(),Box<dynError>>{// Create a new Yjs document and treelet doc = Arc::new(yrs::Doc::new());let tree = Tree::new(doc.clone(),"test")?;// Subscribe to tree changeslet sub = tree.on_change(|e| {match e {TreeEvent::TreeUpdated(tree) => {// Print a textual representation of the treeprintln!("{}", tree);}TreeEvent::TreePoisoned(_tree, err) => {println!("Tree was poisoned! {}", err);}}});// Create and manipulate nodeslet node1 = tree.create_child_with_id("1")?;let node2 = tree.create_child_with_id("2")?;let node3 = node1.create_child_with_id("3")?;let node4 = node2.create_child_with_id("4")?;// Move nodes around
node3.move_to(&node2,Some(0))?;// Move node3 to be first child of node2
node1.move_after(&node2)?;// Move node1 to be after node2
node4.move_before(&node3)?;// Move node4 to be before node3// Store data on a node
node1.set("my_key","my_value")?;// Get data from a nodelet val = node1.get_as::<String>("my_key")?;assert_eq!(val.as_str(),"my_value");// Iterate over the tree in depth-first orderlet nodes = tree
.traverse(TraversalOrder::DepthFirst).map(|n| (n.id().to_string(), n.depth())).collect::<Vec<_>>();assert_eq!(
nodes,
vec![("<ROOT>",0),("2",1),("3",2),("4",2),("1",1)].iter().map(|(id, depth)| (id.to_string(),*depth asusize)).collect::<Vec<_>>());Ok(())}See the examples folder in the repository for more.