To run: `cargo +nightly -Zscript ./wit_doc_comment.rs`

wit_doc_comment.rs

---cargo
[dependencies]
tree-sitter-wit = { git = "https://github.com/bytecodealliance/tree-sitter-wit", version = "1.2.0" }
tree-sitter = "0.25.10"
---

use tree_sitter::{Parser, Point, Query, QueryCursor, StreamingIterator};

const WIT_FILE: &str = "
/// DOC COMMENT `wasmcloud`
package wasmcloud:bus@1.0.0;

// NOT a doc comment!
interface lattice {
    /// NO MATCH doc comment, it does not immediately precede an object

    no-match: func() -> bool;

    /// DOC COMMENT `call-target-interface`
    resource call-target-interface {
        constructor(namespace: string, %package: string, %interface: string);
    }

    /// DOC COMMENT for call-target-interface
    set-link-name: func(name: string, interfaces: list<call-target-interface>);
}
";

// match a doc comment string that is immediately followed by a node without the
// `doc` field (!doc)
const QUERY_STR: &str = "((_ (doc_comment)) @obj_comment . (_ !doc) @obj)";

fn main() {
    let mut parser = Parser::new();
    parser
        .set_language(&tree_sitter_wit::LANGUAGE.into())
        .expect("Error loading WIT grammar");

    let tree = parser.parse(WIT_FILE, None).unwrap();
    let root_node = tree.root_node();
    let query = Query::new(&tree_sitter_wit::LANGUAGE.into(), QUERY_STR).unwrap();
    let mut cursor = QueryCursor::new();

    let mut matches = cursor.matches(&query, root_node, WIT_FILE.as_bytes());
    while let Some(mat) = matches.next() {
        let [end, obj] = mat.captures.try_into().unwrap();
        // https://docs.rs/tree-sitter/latest/tree_sitter/struct.Node.html#method.is_named
        if !obj.node.is_named() {
            continue;
        }

        // struct Point { row, column }
        let comment_start: Point = end.node.start_position();
        let obj_start: Point = obj.node.start_position();
        // this means our obj is not immediately preceded by doc comment
        if comment_start.row + 1 != obj_start.row {
            continue;
        }
        let doc_comment_str = &WIT_FILE[end.node.byte_range()].trim();
        let obj_str = &WIT_FILE[obj.node.byte_range()].trim();
        println!("<\n  doc_comment[{comment_start}]: {doc_comment_str}");
        println!("  obj[{obj_start}]: {obj_str}\n>");
    }
}