matzo/src/main.rs

use matzo::grammar::StmtsParser;
use matzo::interp::State;
use matzo::lexer::tokens;

fn run(src: &str) {
    let lexed = tokens(&src);
    let stmts = StmtsParser::new().parse(lexed).unwrap();
    let mut state = State::new();
    for stmt in stmts {
        if let Err(err) = state.execute(&stmt) {
            eprintln!("error: {}", err);
        }
    }
}

fn run_repl() -> Result<(), Box<dyn std::error::Error>> {
    let mut rl = rustyline::Editor::<()>::new();
    let mut state = State::new();
    let parser = StmtsParser::new();
    println!(
        "{}",
        ansi_term::Colour::Blue.bold().paint("matzo interpreter"),
    );
    println!(
        "{}",
        ansi_term::Colour::Blue.paint("(work-in-progress)"),
    );

    loop {
        let line = match rl.readline(">>> ") {
            Ok(ln) => ln,
            Err(rustyline::error::ReadlineError::Eof) |
            Err(rustyline::error::ReadlineError::Interrupted) =>
                return Ok(()),
            err => err?,
        };
        let lexed = tokens(&line);

        let stmts = match parser.parse(lexed) {
            Ok(stmts) => stmts,
            Err(err) => {
                // for the REPL specifically, let's try adding a
                // `puts` to see if that works
                let added_puts = format!("puts {}", line);
                let lexed = tokens(&added_puts);
                match parser.parse(lexed) {
                    Ok(stmts) => stmts,
                    Err(_) => {
                        // that didn't fix it, so report the
                        // _original_ parse error, not the new one
                        eprintln!(
                            "{}",
                            ansi_term::Colour::Red.paint(
                                format!("{:?}", err)
                            ),
                        );
                        continue;
                    }
                }
            }
        };

        for stmt in stmts {
            if let Err(err) = state.execute(&stmt) {
                eprintln!(
                    "{} {}",
                    ansi_term::Colour::Red.bold().paint("error:"),
                    ansi_term::Colour::Red.paint(format!("{}", err)),
                );
            }
        }
    }
}

fn main() {
    let args = std::env::args().skip(1).collect::<Vec<String>>();
    if args.is_empty() {
        run_repl().unwrap();
        return;
    }

    for arg in args {
        let buf = std::fs::read_to_string(arg).unwrap();
        run(&buf);
    }
}