mute/mute-macros/src/lib.rs

use mute_parser::{parse_str, Node};
use proc_macro::TokenStream;

#[proc_macro]
pub fn inline(input: TokenStream) -> TokenStream {
    let ast = parse_str(input.to_string().as_str()).unwrap();
    if ast.len() != 1 {
        panic!("Expected a single expression, got multiple");
    }

    ast.into_iter()
        .map(format_node)
        .reduce(|lhs, rhs| format!("{lhs}\n{rhs}"))
        .unwrap_or("Node::Nil".to_string())
        .parse::<TokenStream>()
        .unwrap()
}

fn format_node(node: Node) -> String {
    match node {
        Node::List(v) => {
            let vec = v
                .into_iter()
                .map(format_node)
                .reduce(|lhs, rhs| format!("{lhs}, {rhs}"))
                .unwrap_or_default();

            format!("Node::List(vec![{vec}])")
        }

        Node::Symbol(s) => format!("Node::Symbol(\"{s}\".to_string())"),
        Node::Keyword(k) => format!("Node::Keyword(\"{k}\".to_string())"),
        Node::Int(i) => format!("Node::Int({i})"),
        Node::Float(f) => format!("Node::Float({f})"),
        Node::String(s) => format!("Node::String(\"{s}\".to_string())"),
        Node::Boolean(b) => format!("Node::Bool({b})"),
        Node::Nil => "Node::Nil".to_string(),
        Node::Void => "Node::Void".to_string(),

        Node::Error(e) => format!("Node::Error(\"{e}\".to_string())"),

        Node::Vector(v) => {
            let vec = v
                .into_iter()
                .map(format_node)
                .reduce(|lhs, rhs| format!("{lhs}, {rhs}"))
                .unwrap_or_default();

            format!("Node::Vector(vec![{vec}])")
        }
        Node::Map(v) => {
            let vec = v
                .into_iter()
                .map(|(k, v)| (k, format_node(v)))
                .map(|(k, v)| format!("({k}, {v})"))
                .reduce(|lhs, rhs| format!("{lhs}, {rhs}"))
                .unwrap_or_default();

            format!("Node::Hashmap(vec![{vec}].into())")
        }

        Node::Define { args } => {
            let args = args
                .into_iter()
                .map(|(k, v)| format!("(\"{}\".to_string(), {})", k, format_node(v)))
                .reduce(|lhs, rhs| format!("{lhs}, {rhs}"))
                .unwrap_or_default();

            format!("Node::Define(vec![{args}])")
        }
        Node::Let { args, body } => {
            let args = args
                .into_iter()
                .map(|(k, v)| (k, format_node(v)))
                .fold(String::new(), |lhs, (k, v)| {
                    format!("{lhs}, ({k}.to_string(), {v})")
                });

            let body = body
                .into_iter()
                .map(format_node)
                .reduce(|lhs, rhs| format!("{lhs}, {rhs}"))
                .unwrap_or_default();

            format!("Node::Let(vec![{}], vec![{}]", args, body)
        }
        Node::Function { parameters, body } => {
            let parameters = parameters
                .into_iter()
                .map(|param| format!("\"{}\".to_string()", param))
                .reduce(|lhs, rhs| format!("{lhs}, {rhs}"))
                .unwrap_or_default();

            let body = body
                .into_iter()
                .map(format_node)
                .reduce(|lhs, rhs| format!("{lhs}, {rhs}"))
                .unwrap_or_default();
            format!(
                "Node::Function {{ parameters: vec![{}], body: vec![{}] }}",
                parameters, body
            )
        }
        Node::Macro { .. } => todo!(),
        Node::If {
            cond,
            consequence,
            alternative,
        } => format!(
            "Node::If(Box::new({}), Box::new({}), Box::new({}))",
            format_node(*cond),
            format_node(*consequence),
            format_node(*alternative)
        ),

        Node::Quote(node) => format!("Node::Quote(Box::new({}))", format_node(*node)),
        Node::Quasiquote(node) => format!("Node::Quasiquote(Box::new({}))", format_node(*node)),
        Node::Unquote(node) => format!("Node::Unquote(Box::new({}))", format_node(*node)),

        Node::Do { body } => {
            let vec = body
                .into_iter()
                .map(format_node)
                .reduce(|lhs, rhs| format!("{lhs}, {rhs}"))
                .unwrap_or_default();

            format!("Node::Do(vec![{vec}])")
        }

        Node::Eval { body } => format!("Node::Eval(Box::new({}))", format_node(*body)),
        Node::Apply { func, args } => format!(
            "Node::Apply(Box::new({}), Box::new({}))",
            format_node(*func),
            format_node(*args)
        ),
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use rstest::rstest;

    macro_rules! set_snapshot_suffix {
        ($($expr:expr),*) => {
            let mut settings = insta::Settings::clone_current();
            settings.set_snapshot_suffix(format!($($expr,)*));
            let _guard = settings.bind_to_scope();
        }
    }

    #[rstest]
    // Basic values
    #[case("()")]
    #[case("(+ 1 2 3)")]
    #[case("1")]
    #[case("1.0")]
    #[case("\"uwu\"")]
    #[case("true")]
    #[case("false")]
    #[case("asdf")]
    #[case("nil")]
    #[case("[1 2 3]")]
    #[case("{:a 1 :b 2 :c 3}")]
    // Specials
    #[case("(define (a 1))")]
    #[case("(define (a 1) (b 2))")]
    #[case("(fn* () (+ 1 1))")]
    #[case("(fn* (a b) (+ a b))")]
    #[case("(if true 1 2)")]
    fn test_format_node(#[case] input: &str) {
        set_snapshot_suffix!("{}", input);

        let ast = parse_str(input).unwrap();
        let res = format_node(ast[0].clone());
        insta::assert_snapshot!(res);
    }
}