use tree_sitter::{Node, Tree};

use tree_sitter_traversal::{traverse, traverse_tree, Order};
fn get_tree() -> Tree {
    use tree_sitter::Parser;
    let mut parser = Parser::new();
    let lang = tree_sitter_rust::language();
    parser.set_language(lang).expect("Error loading Rust grammar");
    return parser.parse("fn double(x: usize) -> usize { x * 2 }", None).expect("Error parsing provided code");
}

fn main() {
    use std::collections::HashSet;
    use std::iter::FromIterator;
    let tree: Tree = get_tree();
    let preorder: Vec<Node<'_>> = traverse(tree.walk(), Order::Pre).collect::<Vec<_>>();
    let postorder: Vec<Node<'_>> = traverse_tree(&tree, Order::Post).collect::<Vec<_>>();
    // For any tree with more than just a root node,
    // the order of preorder and postorder will be different
    assert_ne!(preorder, postorder);
    // However, they will have the same amount of nodes
    assert_eq!(preorder.len(), postorder.len());
    // Specifically, they will have the exact same nodes, just in a different order
    assert_eq!(
        <HashSet<_>>::from_iter(preorder.into_iter()),
        <HashSet<_>>::from_iter(postorder.into_iter())
    );   
}