use rhai::{Dynamic, Engine, EvalAltResult, Scope, AST}; #[cfg(not(feature = "no_optimize"))] use rhai::OptimizationLevel; use std::io::{stdin, stdout, Write}; fn print_error(input: &str, err: EvalAltResult) { let lines: Vec<_> = input.trim().split('\n').collect(); let pos = err.position(); let line_no = if lines.len() > 1 { if pos.is_none() { "".to_string() } else { format!("{}: ", pos.line().unwrap()) } } else { "".to_string() }; // Print error let pos_text = format!(" ({})", pos); if pos.is_none() { // No position println!("{}", err); } else { // Specific position println!("{}{}", line_no, lines[pos.line().unwrap() - 1]); let err_text = match err { EvalAltResult::ErrorRuntime(err, _) if !err.is_empty() => { format!("Runtime error: {}", err) } err => err.to_string(), }; println!( "{0:>1$} {2}", "^", line_no.len() + pos.position().unwrap(), err_text.replace(&pos_text, "") ); } } fn print_help() { println!("help => print this help"); println!("quit, exit => quit"); println!("scope => print all variables in the scope"); println!("ast => print the last AST"); println!("astu => print the last raw, un-optimized AST"); println!(r"end a line with '\' to continue to the next line."); println!(); } fn main() { let mut engine = Engine::new(); #[cfg(not(feature = "no_optimize"))] engine.set_optimization_level(OptimizationLevel::None); let mut scope = Scope::new(); let mut input = String::new(); let mut main_ast: AST = Default::default(); let mut ast_u: AST = Default::default(); let mut ast: AST = Default::default(); println!("Rhai REPL tool"); println!("=============="); print_help(); 'main_loop: loop { print!("rhai> "); stdout().flush().expect("couldn't flush stdout"); input.clear(); loop { match stdin().read_line(&mut input) { Ok(0) => break 'main_loop, Ok(_) => (), Err(err) => panic!("input error: {}", err), } let line = input.as_str().trim_end(); // Allow line continuation if line.ends_with('\\') { let len = line.len(); input.truncate(len - 1); input.push('\n'); } else { break; } print!("> "); stdout().flush().expect("couldn't flush stdout"); } let script = input.trim(); if script.is_empty() { continue; } // Implement standard commands match script { "help" => { print_help(); continue; } "exit" | "quit" => break, // quit "scope" => { scope .iter() .enumerate() .for_each(|(i, (name, value))| println!("[{}] {} = {:?}", i + 1, name, value)); continue; } "astu" => { // print the last un-optimized AST println!("{:#?}", &ast_u); continue; } "ast" => { // print the last AST println!("{:#?}", &ast); continue; } _ => (), } match engine .compile_with_scope(&scope, &script) .map_err(Into::into) .and_then(|r| { ast_u = r.clone(); #[cfg(not(feature = "no_optimize"))] { ast = engine.optimize_ast(&scope, r, OptimizationLevel::Full); } #[cfg(feature = "no_optimize")] { ast = r; } // Merge the AST into the main main_ast = main_ast.merge(&ast); // Evaluate engine.eval_ast_with_scope::(&mut scope, &main_ast) }) { Ok(result) if !result.is::<()>() => { println!("=> {:?}", result); println!(); } Ok(_) => (), Err(err) => { println!(); print_error(&input, *err); println!(); } } // Throw away all the statements, leaving only the functions main_ast.clear_statements(); } }