rhai_trace

rhai_trace is a lightweight Rust library that enhances Rhai scripts with better error reporting and span tracking. It walks the script's AST, extracts spans for statements and expressions, and provides structured error information that can be used with any diagnostic or pretty-printing crate.

With rhai_trace, you can:

• Extract spans (start/end byte offsets, line, column) from Rhai scripts.
• Get detailed runtime error diagnostics including messages, hints, and notes.
• Integrate easily with crates like ariadne or other diagnostic systems.

Quick Example

use rhai_trace::{SpanTracer, BetterError};
use rhai::Engine;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Example Rhai code
    let code = r#"
        let a = 42;
        let b = a + 1;
        fn multiply(x, y) { x * y }
        let c = multiply("a", 7);  // <-- will trigger runtime error
    "#;

    // Initialize the span tracer
    let tracer = SpanTracer::new();

    // Extract spans from the code
    let spans = tracer.extract_from(code)?;

    println!("Extracted spans:");
    for span in &spans {
        println!("{}..{}: '{}'",
            span.start(),
            span.end(),
            &code[span.start()..span.end()]
        );
    }

    // Attempt to execute the code with Rhai engine
    let engine = Engine::new();
    match engine.eval::<rhai::Dynamic>(code) {
        Ok(result) => println!("Execution result: {:?}", result),
        Err(e) => {
            // Improve the error using our library
            if let Ok(better) = BetterError::improve_eval_error(&e, code, &engine) {
                // ...
            } else {
                eprintln!("Original Error: {:?}", e);
            }
        }
    }

    Ok(())
}

Full Example

For a complete working example showing integration with ariadne for pretty error reporting, see the example folder in the repository:

GitHub Example