facet

Thanks to all individual and corporate sponsors, without whom this work could not exist:

facet provides runtime reflection for Rust.

Any type that implements Facet trait returns a Shape, which describes:

• The memory layout of the type
• Its definition: struct fields, underlying type for newtypes, etc.
• How to drop it in place

The Poke type is able to allocate (or work from a &mut MaybeUninit<T>) any Facet type, and gradually initialize its fields — until the fully-built value is moved out of the partial.

The Peek type helps perform read operations on any Facet type.

It comes with a derive macro that uses unsynn for speed of compilation.

Ecosystem

The main facet crate re-exports symbols from:

• facet-trait, which defines the main Facet trait and implements it for foreign types (mostly libstd)
• facet-types, which defines the Shape struct, along with various vtables and the whole Def tree
• facet-opaque, which provides helpers around type-erased pointers like OpaqueUninit, OpaqueConst, Opaque
• facet-derive, which implements the Facet derive attribute as a fast/light proc macro powered by unsynn
• facet-spez, which implements an autoderef specialization trick needed for facet-derive
• facet-peek, which allows reading arbitrary Facet types
• facet-poke, which allows building/altering arbitrary Facet types

facet supports deserialization from multiple data formats through dedicated crates:

• facet-json: JSON deserialization
• facet-yaml: YAML deserialization
• facet-msgpack: MessagePack deserialization
• facet-urlencoded: URL-encoded form data deserialization

Additionally:

• facet-pretty is able to pretty-print Facet types.
• facet-codegen is internal and generates some of the code of facet-core

Example usage

facet-json is the one that gets updated first — look at it.

License

Licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.