# facet-postcard

Postcard serialization and deserialization for Facet types.

[Postcard](https://github.com/jamesmunns/postcard) is a compact, efficient binary serialization format designed for embedded and `no_std` environments. This crate provides byte-for-byte compatible output with the standard `postcard` crate, while using Facet's reflection capabilities instead of serde.

## Features

- Compact binary format optimized for size
- Byte-for-byte compatibility with the `postcard` crate
- `no_std` support with the `alloc` feature
- Zero-copy deserialization where possible

## Usage

```rust
use facet::Facet;
use facet_postcard::{to_vec, from_slice};

#[derive(Debug, Facet)]
struct Message {
    id: u32,
    payload: Vec<u8>,
}

// Serialize
let msg = Message { id: 42, payload: vec![1, 2, 3] };
let bytes = to_vec(&msg).unwrap();

// Deserialize
let decoded: Message = from_slice(&bytes).unwrap();
```

For `no_std` environments without an allocator, use `to_slice`:

```rust
# use facet::Facet;
# #[derive(Debug, Facet)]
# struct Message { id: u32, payload: Vec<u8> }
# let msg = Message { id: 42, payload: vec![1, 2, 3] };
let mut buf = [0u8; 64];
let used = facet_postcard::to_slice(&msg, &mut buf).unwrap();
```

## Feature Flags

- `std` (default): Enables standard library support
- `alloc`: Enables heap allocation without full std (for `no_std` with allocator)


