rml/
cst_convert.rs

1//! Universal CST converter dispatch (issue #138).
2//!
3//! Single entry point that turns host-language source into a `.lino` CST and
4//! back. Mirrors `js/src/cst-convert.mjs`. Provides:
5//!
6//! - [`parse_to_cst`] — host source → CST.
7//! - [`print_from_cst`] — CST → host source.
8//! - [`round_trip`] — convenience helper that asserts byte fidelity.
9//!
10//! Supported `lang` values: `"rust"`, `"js"` (or `"javascript"`), `"lean"`, `"rocq"`.
11
12use crate::cst::CstNode;
13use crate::cst_js::{parse_js, print_js};
14use crate::cst_lean::{parse_lean, print_lean};
15use crate::cst_rocq::{parse_rocq, print_rocq};
16use crate::cst_rust::{parse_rust, print_rust};
17
18/// The four host languages plus the `javascript` alias.
19pub const SUPPORTED_LANGUAGES: &[&str] = &["rust", "js", "javascript", "lean", "rocq"];
20
21/// Parse host-language source into a `.lino` CST.
22pub fn parse_to_cst(src: &str, lang: &str) -> Result<CstNode, String> {
23    match lang {
24        "rust" => Ok(parse_rust(src)),
25        "js" | "javascript" => Ok(parse_js(src)),
26        "lean" => Ok(parse_lean(src)),
27        "rocq" => Ok(parse_rocq(src)),
28        other => Err(format!("unsupported language for parse_to_cst: {}", other)),
29    }
30}
31
32/// Print a CST node back to host-language source.
33pub fn print_from_cst(node: &CstNode, lang: &str) -> Result<String, String> {
34    match lang {
35        "rust" => Ok(print_rust(node)),
36        "js" | "javascript" => Ok(print_js(node)),
37        "lean" => Ok(print_lean(node)),
38        "rocq" => Ok(print_rocq(node)),
39        other => Err(format!("unsupported language for print_from_cst: {}", other)),
40    }
41}
42
43/// Result of a round-trip check.
44pub struct RoundTripResult {
45    pub ok: bool,
46    pub source: String,
47    pub round_tripped: String,
48}
49
50/// Verify that `print_from_cst(parse_to_cst(src, lang), lang) == src`.
51pub fn round_trip(src: &str, lang: &str) -> Result<RoundTripResult, String> {
52    let cst = parse_to_cst(src, lang)?;
53    let round_tripped = print_from_cst(&cst, lang)?;
54    Ok(RoundTripResult {
55        ok: round_tripped == src,
56        source: src.to_string(),
57        round_tripped,
58    })
59}
60
61#[cfg(test)]
62mod tests {
63    use super::*;
64
65    #[test]
66    fn dispatches_by_language_name() {
67        for lang in &["rust", "js", "lean", "rocq"] {
68            let sample = if *lang == "rocq" {
69                "Definition x := 1.\n"
70            } else {
71                "x\n"
72            };
73            let out = print_from_cst(&parse_to_cst(sample, lang).unwrap(), lang).unwrap();
74            assert_eq!(out, sample);
75        }
76    }
77
78    #[test]
79    fn javascript_alias_works_like_js() {
80        let src = "const x = 1;\n";
81        let out =
82            print_from_cst(&parse_to_cst(src, "javascript").unwrap(), "javascript").unwrap();
83        assert_eq!(out, src);
84    }
85
86    #[test]
87    fn rejects_unsupported_language() {
88        assert!(parse_to_cst("x", "python").is_err());
89        let n = CstNode::list("x", vec![]);
90        assert!(print_from_cst(&n, "python").is_err());
91    }
92
93    #[test]
94    fn round_trip_helper_reports_ok() {
95        let r = round_trip("fn main() {}\n", "rust").unwrap();
96        assert!(r.ok);
97        assert_eq!(r.round_tripped, "fn main() {}\n");
98    }
99}
rml/cst_convert.rs

rml/
cst_convert.rs
