Struct rustc_metadata::rmeta::LazyValue

struct LazyValue<T> {
    position: NonZeroUsize,
    _marker: PhantomData<fn() -> T>,
}

A value of type T referred to by its absolute position in the metadata, and which can be decoded lazily.

Metadata is effective a tree, encoded in post-order, and with the root’s position written next to the header. That means every single LazyValue points to some previous location in the metadata and is part of a larger node.

The first LazyValue in a node is encoded as the backwards distance from the position where the containing node starts and where the LazyValue points to, while the rest use the forward distance from the previous LazyValue. Distances start at 1, as 0-byte nodes are invalid. Also invalid are nodes being referred in a different order than they were encoded in.

Fields

position: NonZeroUsize

_marker: PhantomData<fn() -> T>

Implementations

impl<T: ParameterizedOverTcx> LazyValue<T>

fn decode<'a, 'tcx, M: Metadata<'a, 'tcx>>(self, metadata: M) -> T::Value<'tcx>

where T::Value<'tcx>: Decodable<DecodeContext<'a, 'tcx>>,

impl<T> LazyValue<T>

fn from_position(position: NonZeroUsize) -> LazyValue<T>

Trait Implementations

impl<T> Clone for LazyValue<T>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a, 'tcx, T> Decodable<DecodeContext<'a, 'tcx>> for LazyValue<T>

fn decode(decoder: &mut DecodeContext<'a, 'tcx>) -> Self

impl<'a, 'tcx, T> Encodable<EncodeContext<'a, 'tcx>> for LazyValue<T>

fn encode(&self, e: &mut EncodeContext<'a, 'tcx>)

impl<T: ParameterizedOverTcx> ParameterizedOverTcx for LazyValue<T>

type Value<'tcx> = LazyValue<<T as ParameterizedOverTcx>::Value<'tcx>>

impl<T> Copy for LazyValue<T>

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 8 bytes