traverse_ast.rs

use std::path::Path;

use clang_rs_binding::clang::Clang;
use clang_rs_binding::index::{from_payload, to_payload, ChildVisitResult, Cursor, Payload};

fn visitor(cursor: &Cursor, _parent: &Cursor, payload: Payload) -> i32 {
    if cursor.is_from_main_file() {
        return ChildVisitResult::CONTINUE;
    }
    let cursor_kind_spelling = cursor.kind_spelling();
    let cursor_spelling = cursor.spelling();
    let payload = unsafe { from_payload::<AstDataPayload>(payload) };
    let new_buf = payload.borrow().buf.clone()
        + &format!(
            "{:-<width$} {} ({})\n",
            "",
            cursor_kind_spelling,
            cursor_spelling,
            width = payload.borrow().level as usize,
        );
    payload.borrow_mut().buf = new_buf;
    let children_payload = AstDataPayload::new(AstData {
        level: payload.borrow().level + 1,
        buf: String::new(),
    });
    cursor.visit_children(visitor, to_payload(&children_payload));
    payload.borrow_mut().buf += &children_payload.borrow().buf;
    ChildVisitResult::CONTINUE
}

#[derive(Debug, Default)]
struct AstData {
    level: i32,
    buf: String,
}
type AstDataPayload = std::cell::RefCell<AstData>;

fn collect_ast(cursor: &Cursor<'_>) -> String {
    let data = AstDataPayload::new(AstData {
        level: 0,
        buf: String::new(),
    });
    cursor.visit_children(visitor, to_payload(&data));
    data.take().buf
}

fn generate_ast<P: AsRef<Path>>(filename: P) -> impl AsRef<Path> {
    let ast_filename = Path::new("traverse_ast.ast");
    std::process::Command::new("clang++")
        .arg("-emit-ast")
        .arg(filename.as_ref())
        .status()
        .unwrap_or_else(|e| {
            panic!(
                "clang should generate .ast for {}, {}",
                filename.as_ref().to_string_lossy(),
                e
            )
        });
    assert!(ast_filename.exists());
    ast_filename
}

fn read_test_oracle<P: AsRef<Path>>(filename: P) -> String {
    std::fs::read_to_string(filename).unwrap()
}

#[test]
fn traverse_ast_works() {
    let traverse_ast_dir = std::path::Path::new("tests/artifacts/traverse_ast");
    let ast_filename = generate_ast(traverse_ast_dir.join("traverse_ast.cpp"));
    let oracle = read_test_oracle(traverse_ast_dir.join("traverse_ast.test_oracle"));

    let clang = Clang::default();
    let index = clang.create_index_with_display_diagnostics();
    let tu = index.create_translation_unit(&ast_filename);
    let cursor = tu.create_cursor();
    let buf = collect_ast(&cursor);

    assert_eq!(buf, oracle);
}