maybe-serde

Using specialization feature for present optional impl serde::{Serialize, Deserialize}

So it require nightly rust

All types impl MaydeSer and MeybeDe

If type impl Serialize then MeybeSer::maybe_serialize return Serialize::serialize with Some but not then return None

same as MaydeDe and Deserialize

Example(test code in src)

```rust use super::{MaybeDe, MaybeSer}; use serdederive::{Deserialize, Serialize}; use serdejson::{de::StrRead, Deserializer, Result, Serializer};

fn ser_fn<V>(val: &V) -> Option<Result<()>>
where
    V: MaybeSer,
{
    let mut buf = Vec::new();
    val.maybe_serialize(&mut Serializer::new(&mut buf))
}

fn de_fn<'de, V>(text: &'de str) -> Option<Result<V>>
where
    V: MaybeDe<'de>,
{
    V::maybe_deserialize(&mut Deserializer::new(StrRead::new(text)))
}

#[test]
fn serde_none() {
    struct NoneSerde(i32);

    assert!(ser_fn(&NoneSerde(123)).is_none());
    assert!(de_fn::<NoneSerde>("123").is_none());
}

#[test]
fn serde_some() {
    #[derive(Serialize, Deserialize)]
    struct SomeSerde(i32);

    assert!(ser_fn(&SomeSerde(123)).is_some());
    assert_eq!(de_fn::<SomeSerde>("123").unwrap().unwrap().0, 123);
}

```