tests/ffi/lib.rs

use cxx::{CxxString, UniquePtr};
use std::fmt::{self, Display};

#[cxx::bridge(namespace = tests)]
pub mod ffi {
    struct Shared {
        z: usize,
    }

    extern "C" {
        include!("tests/ffi/tests.h");

        type C;

        fn c_return_primitive() -> usize;
        fn c_return_shared() -> Shared;
        fn c_return_box() -> Box<R>;
        fn c_return_unique_ptr() -> UniquePtr<C>;
        fn c_return_ref(shared: &Shared) -> &usize;
        fn c_return_str(shared: &Shared) -> &str;
        fn c_return_rust_string() -> String;
        fn c_return_unique_ptr_string() -> UniquePtr<CxxString>;

        fn c_take_primitive(n: usize);
        fn c_take_shared(shared: Shared);
        fn c_take_box(r: Box<R>);
        fn c_take_unique_ptr(c: UniquePtr<C>);
        fn c_take_ref_r(r: &R);
        fn c_take_ref_c(c: &C);
        fn c_take_str(s: &str);
        fn c_take_rust_string(s: String);
        fn c_take_unique_ptr_string(s: UniquePtr<CxxString>);

        fn c_try_return_void() -> Result<()>;
        fn c_try_return_primitive() -> Result<usize>;
        fn c_fail_return_primitive() -> Result<usize>;
    }

    extern "Rust" {
        type R;

        fn r_return_primitive() -> usize;
        fn r_return_shared() -> Shared;
        fn r_return_box() -> Box<R>;
        fn r_return_unique_ptr() -> UniquePtr<C>;
        fn r_return_ref(shared: &Shared) -> &usize;
        fn r_return_str(shared: &Shared) -> &str;
        fn r_return_rust_string() -> String;
        fn r_return_unique_ptr_string() -> UniquePtr<CxxString>;

        fn r_take_primitive(n: usize);
        fn r_take_shared(shared: Shared);
        fn r_take_box(r: Box<R>);
        fn r_take_unique_ptr(c: UniquePtr<C>);
        fn r_take_ref_r(r: &R);
        fn r_take_ref_c(c: &C);
        fn r_take_str(s: &str);
        fn r_take_rust_string(s: String);
        fn r_take_unique_ptr_string(s: UniquePtr<CxxString>);

        fn r_try_return_void() -> Result<()>;
        fn r_try_return_primitive() -> Result<usize>;
        fn r_fail_return_primitive() -> Result<usize>;
    }
}

pub type R = usize;

#[derive(Debug)]
struct Error;

impl std::error::Error for Error {}

impl Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.write_str("rust error")
    }
}

fn r_return_primitive() -> usize {
    2020
}

fn r_return_shared() -> ffi::Shared {
    ffi::Shared { z: 2020 }
}

fn r_return_box() -> Box<R> {
    Box::new(2020)
}

fn r_return_unique_ptr() -> UniquePtr<ffi::C> {
    extern "C" {
        fn cxx_test_suite_get_unique_ptr() -> *mut ffi::C;
    }
    unsafe { UniquePtr::from_raw(cxx_test_suite_get_unique_ptr()) }
}

fn r_return_ref(shared: &ffi::Shared) -> &usize {
    &shared.z
}

fn r_return_str(shared: &ffi::Shared) -> &str {
    let _ = shared;
    "2020"
}

fn r_return_rust_string() -> String {
    "2020".to_owned()
}

fn r_return_unique_ptr_string() -> UniquePtr<CxxString> {
    extern "C" {
        fn cxx_test_suite_get_unique_ptr_string() -> *mut CxxString;
    }
    unsafe { UniquePtr::from_raw(cxx_test_suite_get_unique_ptr_string()) }
}

fn r_take_primitive(n: usize) {
    assert_eq!(n, 2020);
}

fn r_take_shared(shared: ffi::Shared) {
    assert_eq!(shared.z, 2020);
}

fn r_take_box(r: Box<R>) {
    let _ = r;
}

fn r_take_unique_ptr(c: UniquePtr<ffi::C>) {
    let _ = c;
}

fn r_take_ref_r(r: &R) {
    let _ = r;
}

fn r_take_ref_c(c: &ffi::C) {
    let _ = c;
}

fn r_take_str(s: &str) {
    assert_eq!(s, "2020");
}

fn r_take_rust_string(s: String) {
    assert_eq!(s, "2020");
}

fn r_take_unique_ptr_string(s: UniquePtr<CxxString>) {
    assert_eq!(s.as_ref().unwrap().to_str().unwrap(), "2020");
}

fn r_try_return_void() -> Result<(), Error> {
    Ok(())
}

fn r_try_return_primitive() -> Result<usize, Error> {
    Ok(2020)
}

fn r_fail_return_primitive() -> Result<usize, Error> {
    Err(Error)
}