Multi-Indexed Tree in Rust

A generic, flexible, and lightweight multi-indexed tree data structure written in Rust. This library provides hierarchical node storage with support for fast key lookups, tag-based indexing, and multiple traversal strategies.

Features

• Generic Node Structure — Supports any key (K) that implements Eq + Hash + Ord and any value (T).

• Parent & Child Relationships — Each node tracks its parent and children.

• Primary Indexing — Constant-time lookups using a HashMap keyed by node IDs.

• Secondary Indexing — Group nodes under arbitrary tags for quick retrieval.

• Tree Traversal:

  • Depth-first iterator
  • Breadth-first iterator
  • Shortest-path iterator

• Dijkstra-based Shortest Path — Finds all shortest paths between two nodes (assuming unweighted edges).

• Safe Memory Management — Built with Rc + RefCell for shared ownership and interior mutability.

Usage

mod tree;
use tree::MultiIndexedTree;

fn main() {
    // Create a tree with a root node
    let tree = MultiIndexedTree::new("root", "Root Node");

    // Insert child nodes
    tree.insert(&"root", "child1", "First Child").unwrap();
    tree.insert(&"root", "child2", "Second Child").unwrap();

    // Add tags to nodes
    tree.add_to_secondary_index("important".to_string(), "child1".to_string());

    // Lookup nodes by key
    if let Some(node) = tree.find(&"child1") {
        println!("Found: {}", node.value().clone());
    }

    // Depth-first traversal
    for node in tree.iter_depth_first() {
        println!("Node: {}", node.key());
    }
}

Roadmap / TODOs

• Better error handling
• Edge weights for weighted shortest paths
• Parallel traversal with Rayon
• Serialization & deserialization via Serde
• Implement the Display trait for visualization
• Optimize Rc<RefCell<...>> usage where possible

License

MIT License — Free to use, modify, and distribute.