Function proxy_module

crates/tinywasm/tests/host_func_signature_check.rs:129–167

(func_ty: &FuncType)

}

fn proxy_module(func_ty: &FuncType) -> Module {
    let results = func_ty.results();
    let params = func_ty.params();
    let join_surround = |list: &[WasmType], keyword| {
        if list.is_empty() {
            return "".to_string();
        }
        let step = list.iter().map(|ty| format!("{} ", to_name(ty))).collect::<String>();
        format!("({keyword} {step})")
    };

    let results_text = join_surround(results, "result");
    let params_text = join_surround(params, "param");

    let params_gets: String = params.iter().enumerate().fold(String::new(), |mut acc, (num, _)| {
        let _ = writeln!(acc, "(local.get {num})");
        acc
    });

    let result_drops = "(drop)\n".repeat(results.len());
    let wasm_text = format!(
        r#"(module
        (import "host" "hfn" (func $host_fn {params_text} {results_text}))
        (func (export "call_hfn") {params_text} {results_text}
            {params_gets}
            (call $host_fn)
        )
        (func (export "call_hfn_discard") {params_text}
            {params_gets}
            (call $host_fn)
            ;; Keep stack balanced for arbitrary result arity.
            {result_drops}
        )
    )
    "#
    );
    let wasm = wat::parse_str(wasm_text).expect("failed to parse wat");
    tinywasm::parse_bytes(&wasm).expect("failed to make module")
}