//! JavaScript engine — lexer, parser, bytecode, register VM, GC, JIT (AArch64).

use std::fmt;

/// An error produced by the JavaScript engine.
#[derive(Debug)]
pub enum JsError {
    /// The engine does not yet support this feature or syntax.
    NotImplemented,
    /// A parse/syntax error in the source.
    SyntaxError(String),
    /// A runtime error during execution.
    RuntimeError(String),
}

impl fmt::Display for JsError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            JsError::NotImplemented => write!(f, "not implemented"),
            JsError::SyntaxError(msg) => write!(f, "SyntaxError: {}", msg),
            JsError::RuntimeError(msg) => write!(f, "RuntimeError: {}", msg),
        }
    }
}

/// Evaluate a JavaScript source string and return the completion value.
///
/// This is a stub that always returns `NotImplemented`. The real
/// implementation will lex, parse, compile to bytecode, and execute.
pub fn evaluate(_source: &str) -> Result<(), JsError> {
    Err(JsError::NotImplemented)
}