Function deserialize_optional

src/lowertest/src/lib.rs:103–121

If the `stream_iter` is not empty, deserialize the next `TokenTree` into a `D`. See [`to_json`] for the object spec syntax. `type_name` should be `D` in string form. `stream_iter` will advance by one `TokenTree` no matter the result.

(
    stream_iter: &mut I,
    type_name: &'static str,
    ctx: &mut C,
)

///
/// `stream_iter` will advance by one `TokenTree` no matter the result.
pub fn deserialize_optional<D, I, C>(
    stream_iter: &mut I,
    type_name: &'static str,
    ctx: &mut C,
) -> Result<Option<D>, String>
where
    C: TestDeserializeContext,
    D: DeserializeOwned + MzReflect,
    I: Iterator<Item = TokenTree>,
{
    let mut rti = ReflectedTypeInfo::default();
    D::add_to_reflected_type_info(&mut rti);
    match to_json(stream_iter, type_name, &rti, ctx)? {
        Some(j) => Ok(Some(serde_json::from_str::<D>(&j).map_err(|e| {
            format!("String while serializing: {}\nOriginal JSON: {}", e, j)
        })?)),
        None => Ok(None),
    }
}

/// Simpler interface for [deserialize] when no syntax overrides or extensions are needed.
pub fn deserialize_generic<D, I>(stream_iter: &mut I, type_name: &'static str) -> Result<D, String>