pub unsafe trait Lift<UT>: Sized {
type FfiType;
const TYPE_ID_META: MetadataBuffer;
// Required methods
fn try_lift(v: Self::FfiType) -> Result<Self, Error>;
fn try_read(buf: &mut &[u8]) -> Result<Self, Error>;
// Provided method
fn try_lift_from_rust_buffer(v: RustBuffer) -> Result<Self, Error> { ... }
}Expand description
Lift values passed by the foreign code over the FFI into Rust values
This is used by the code generation to handle arguments. It’s usually derived from FfiConverter, except for types that only support lifting but not lowering.
See FfiConverter for a discussion of the methods
Safety
All traits are unsafe (implementing it requires unsafe impl) because we can’t guarantee
that it’s safe to pass your type out to foreign-language code and back again. Buggy
implementations of this trait might violate some assumptions made by the generated code,
or might not match with the corresponding code in the generated foreign-language bindings.
These traits should not be used directly, only in generated code, and the generated code should
have fixture tests to test that everything works correctly together.
Required Associated Types§
type FfiType
Required Associated Constants§
const TYPE_ID_META: MetadataBuffer
Required Methods§
fn try_lift(v: Self::FfiType) -> Result<Self, Error>
fn try_read(buf: &mut &[u8]) -> Result<Self, Error>
Provided Methods§
fn try_lift_from_rust_buffer(v: RustBuffer) -> Result<Self, Error>
fn try_lift_from_rust_buffer(v: RustBuffer) -> Result<Self, Error>
Convenience method
Implementations on Foreign Types§
§impl<UT> Lift<UT> for SystemTime
impl<UT> Lift<UT> for SystemTime
type FfiType = <SystemTime as FfiConverter<UT>>::FfiType
fn try_lift(v: <SystemTime as Lift<UT>>::FfiType) -> Result<SystemTime, Error>
fn try_read(buf: &mut &[u8]) -> Result<SystemTime, Error>
const TYPE_ID_META: MetadataBuffer = <Self as crate::FfiConverter::<UT>>::TYPE_ID_META
§impl<K, V, UT> Lift<UT> for HashMap<K, V, RandomState>where
K: Lift<UT> + Hash + Eq,
V: Lift<UT>,
impl<K, V, UT> Lift<UT> for HashMap<K, V, RandomState>where K: Lift<UT> + Hash + Eq, V: Lift<UT>,
type FfiType = RustBuffer
fn try_read(buf: &mut &[u8]) -> Result<HashMap<K, V, RandomState>, Error>
fn try_lift(buf: RustBuffer) -> Result<HashMap<K, V, RandomState>, Error>
const TYPE_ID_META: MetadataBuffer = MetadataBuffer::from_code(metadata::codes::TYPE_HASH_MAP).concat(K::TYPE_ID_META).concat(V::TYPE_ID_META)
§impl<UT, T> Lift<UT> for Vec<T, Global>where
T: Lift<UT>,
impl<UT, T> Lift<UT> for Vec<T, Global>where T: Lift<UT>,
Support for associative arrays via the FFI - record<u32, u64> in UDL.
HashMaps are currently always passed by serializing to a buffer.
We write a i32 entries count followed by each entry (string
key followed by the value) in turn.
(It’s a signed type due to limits of the JVM).