crafting-interpreters/rust/rox/src/lib.rs

//! Interpret the Lox language. Either compile (interpret for now though) some source code or run a
//! REPL.

use std::{
    fs::{self},
    io::{self, Write},
    path::Path,
};

use tracing::{error, info};

pub mod cli;
pub mod expression;
pub mod interpreter;
pub mod keywords;
pub mod parser;
pub mod scanner;
pub mod token;
pub mod tokenizer {
    pub mod comment;
    pub mod identifier;
    pub mod interface;
    pub mod lookahead;
    pub mod newline;
    pub mod number;
    pub mod single_char;
    pub mod string;
    pub mod whitespace;
}
pub mod value;

/// Read the source code in a file and scan it to tokens.
pub fn compile(source: &Path) -> Result<(), io::Error> {
    let input = fs::read_to_string(source)?;
    run(&input);

    Ok(())
}

/// Run a Lox REPL until SIGINT.
pub fn repl() {
    loop {
        print!("> ");
        let _ = io::stdout().flush();

        let mut input = String::new();
        match io::stdin().read_line(&mut input) {
            Ok(_) => {}
            Err(e) => error!("{}", e),
        }
        let input = input.trim().to_string();
        run(&input);
    }
}

/// Evaluate a Lox input string and print errors or output.
fn run(input: &str) {
    let tokens = scanner::tokenize(input);
    match parser::generate_ast(tokens) {
        Ok(ast) => match interpreter::evaluate(ast) {
            Ok(value) => println!("{value}"),
            Err(e) => error!("{e}"),
        },
        Err(e) => error!("{e}"),
    }
}