rpc.rs.html -- source
Description: Source to the Rust file `src\libproc_macro\bridge\rpc.rs`.
Keywords: rust, rustlang, rust-lang

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    //! Serialization for client-server communication.

    use std::any::Any;
    use std::char;
    use std::io::Write;
    use std::num::NonZeroU32;
    use std::ops::Bound;
    use std::str;

    pub(super) type Writer = super::buffer::Buffer<u8>;

    pub(super) trait Encode<S>: Sized {
        fn encode(self, w: &mut Writer, s: &mut S);
    }

    pub(super) type Reader<'a> = &'a [u8];

    pub(super) trait Decode<'a, 's, S>: Sized {
        fn decode(r: &mut Reader<'a>, s: &'s S) -> Self;
    }

    pub(super) trait DecodeMut<'a, 's, S>: Sized {
        fn decode(r: &mut Reader<'a>, s: &'s mut S) -> Self;
    }

    macro_rules! rpc_encode_decode {
        (le $ty:ty) => {
            impl<S> Encode<S> for $ty {
                fn encode(self, w: &mut Writer, _: &mut S) {
                    w.write_all(&self.to_le_bytes()).unwrap();
                }
            }

            impl<S> DecodeMut<'_, '_, S> for $ty {
                fn decode(r: &mut Reader<'_>, _: &mut S) -> Self {
                    const N: usize = ::std::mem::size_of::<$ty>();

                    let mut bytes = [0; N];
                    bytes.copy_from_slice(&r[..N]);
                    *r = &r[N..];

                    Self::from_le_bytes(bytes)
                }
            }
        };
        (struct $name:ident { $($field:ident),* $(,)? }) => {
            impl<S> Encode<S> for $name {
                fn encode(self, w: &mut Writer, s: &mut S) {
                    $(self.$field.encode(w, s);)*
                }
            }

            impl<S> DecodeMut<'_, '_, S> for $name {
                fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
                    $name {
                        $($field: DecodeMut::decode(r, s)),*
                    }
                }
            }
        };
        (enum $name:ident $(<$($T:ident),+>)? { $($variant:ident $(($field:ident))*),* $(,)? }) => {
            impl<S, $($($T: Encode<S>),+)?> Encode<S> for $name $(<$($T),+>)? {
                fn encode(self, w: &mut Writer, s: &mut S) {
                    // HACK(eddyb): `Tag` enum duplicated between the
                    // two impls as there's no other place to stash it.
                    #[allow(non_upper_case_globals)]
                    mod tag {
                        #[repr(u8)] enum Tag { $($variant),* }

                        $(pub const $variant: u8 = Tag::$variant as u8;)*
                    }

                    match self {
                        $($name::$variant $(($field))* => {
                            tag::$variant.encode(w, s);
                            $($field.encode(w, s);)*
                        })*
                    }
                }
            }

            impl<S, $($($T: for<'s> DecodeMut<'a, 's, S>),+)?> DecodeMut<'a, '_, S>
                for $name $(<$($T),+>)?
            {
                fn decode(r: &mut Reader<'a>, s: &mut S) -> Self {
                    // HACK(eddyb): `Tag` enum duplicated between the
                    // two impls as there's no other place to stash it.
                    #[allow(non_upper_case_globals)]
                    mod tag {
                        #[repr(u8)] enum Tag { $($variant),* }

                        $(pub const $variant: u8 = Tag::$variant as u8;)*
                    }

                    match u8::decode(r, s) {
                        $(tag::$variant => {
                            $(let $field = DecodeMut::decode(r, s);)*
                            $name::$variant $(($field))*
                        })*
                        _ => unreachable!(),
                    }
                }
            }
        }
    }

    impl<S> Encode<S> for () {
        fn encode(self, _: &mut Writer, _: &mut S) {}
    }

    impl<S> DecodeMut<'_, '_, S> for () {
        fn decode(_: &mut Reader<'_>, _: &mut S) -> Self {}
    }

    impl<S> Encode<S> for u8 {
        fn encode(self, w: &mut Writer, _: &mut S) {
            w.write_all(&[self]).unwrap();
        }
    }

    impl<S> DecodeMut<'_, '_, S> for u8 {
        fn decode(r: &mut Reader<'_>, _: &mut S) -> Self {
            let x = r[0];
            *r = &r[1..];
            x
        }
    }

    rpc_encode_decode!(le u32);
    rpc_encode_decode!(le usize);

    impl<S> Encode<S> for bool {
        fn encode(self, w: &mut Writer, s: &mut S) {
            (self as u8).encode(w, s);
        }
    }

    impl<S> DecodeMut<'_, '_, S> for bool {
        fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
            match u8::decode(r, s) {
                0 => false,
                1 => true,
                _ => unreachable!(),
            }
        }
    }

    impl<S> Encode<S> for char {
        fn encode(self, w: &mut Writer, s: &mut S) {
            (self as u32).encode(w, s);
        }
    }

    impl<S> DecodeMut<'_, '_, S> for char {
        fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
            char::from_u32(u32::decode(r, s)).unwrap()
        }
    }

    impl<S> Encode<S> for NonZeroU32 {
        fn encode(self, w: &mut Writer, s: &mut S) {
            self.get().encode(w, s);
        }
    }

    impl<S> DecodeMut<'_, '_, S> for NonZeroU32 {
        fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
            Self::new(u32::decode(r, s)).unwrap()
        }
    }

    impl<S, A: Encode<S>, B: Encode<S>> Encode<S> for (A, B) {
        fn encode(self, w: &mut Writer, s: &mut S) {
            self.0.encode(w, s);
            self.1.encode(w, s);
        }
    }

    impl<S, A: for<'s> DecodeMut<'a, 's, S>, B: for<'s> DecodeMut<'a, 's, S>> DecodeMut<'a, '_, S>
        for (A, B)
    {
        fn decode(r: &mut Reader<'a>, s: &mut S) -> Self {
            (DecodeMut::decode(r, s), DecodeMut::decode(r, s))
        }
    }

    rpc_encode_decode!(
        enum Bound<T> {
            Included(x),
            Excluded(x),
            Unbounded,
        }
    );

    rpc_encode_decode!(
        enum Option<T> {
            None,
            Some(x),
        }
    );

    rpc_encode_decode!(
        enum Result<T, E> {
            Ok(x),
            Err(e),
        }
    );

    impl<S> Encode<S> for &[u8] {
        fn encode(self, w: &mut Writer, s: &mut S) {
            self.len().encode(w, s);
            w.write_all(self).unwrap();
        }
    }

    impl<S> DecodeMut<'a, '_, S> for &'a [u8] {
        fn decode(r: &mut Reader<'a>, s: &mut S) -> Self {
            let len = usize::decode(r, s);
            let xs = &r[..len];
            *r = &r[len..];
            xs
        }
    }

    impl<S> Encode<S> for &str {
        fn encode(self, w: &mut Writer, s: &mut S) {
            self.as_bytes().encode(w, s);
        }
    }

    impl<S> DecodeMut<'a, '_, S> for &'a str {
        fn decode(r: &mut Reader<'a>, s: &mut S) -> Self {
            str::from_utf8(<&[u8]>::decode(r, s)).unwrap()
        }
    }

    impl<S> Encode<S> for String {
        fn encode(self, w: &mut Writer, s: &mut S) {
            self[..].encode(w, s);
        }
    }

    impl<S> DecodeMut<'_, '_, S> for String {
        fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
            <&str>::decode(r, s).to_string()
        }
    }

    /// Simplied version of panic payloads, ignoring
    /// types other than `&'static str` and `String`.
    pub enum PanicMessage {
        StaticStr(&'static str),
        String(String),
        Unknown,
    }

    impl From<Box<dyn Any + Send>> for PanicMessage {
        fn from(payload: Box<dyn Any + Send + 'static>) -> Self {
            if let Some(s) = payload.downcast_ref::<&'static str>() {
                return PanicMessage::StaticStr(s);
            }
            if let Ok(s) = payload.downcast::<String>() {
                return PanicMessage::String(*s);
            }
            PanicMessage::Unknown
        }
    }

    impl Into<Box<dyn Any + Send>> for PanicMessage {
        fn into(self) -> Box<dyn Any + Send> {
            match self {
                PanicMessage::StaticStr(s) => Box::new(s),
                PanicMessage::String(s) => Box::new(s),
                PanicMessage::Unknown => {
                    struct UnknownPanicMessage;
                    Box::new(UnknownPanicMessage)
                }
            }
        }
    }

    impl PanicMessage {
        pub fn as_str(&self) -> Option<&str> {
            match self {
                PanicMessage::StaticStr(s) => Some(s),
                PanicMessage::String(s) => Some(s),
                PanicMessage::Unknown => None,
            }
        }
    }

    impl<S> Encode<S> for PanicMessage {
        fn encode(self, w: &mut Writer, s: &mut S) {
            self.as_str().encode(w, s);
        }
    }

    impl<S> DecodeMut<'_, '_, S> for PanicMessage {
        fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
            match Option::<String>::decode(r, s) {
                Some(s) => PanicMessage::String(s),
                None => PanicMessage::Unknown,
            }
        }
    }