bevy/crates/bevy_core/src/serde.rs
Sean Sullivan 4b61bbe4e1
bevy_core: Derive useful traits on FrameCount (#13291)
# Objective

I am emboldened by my last small PR and am here with another.

- **Describe the objective or issue this PR addresses.**

It would be nice if `FrameCount` could be used by downstream plugins
that want to use frame data. The example that I have in mind is
[`leafwing_input_playback`](https://github.com/Leafwing-Studios/leafwing_input_playback/issues/29)
which has a [duplicate implementation of
`FrameCount`](https://github.com/Leafwing-Studios/leafwing_input_playback/blob/main/src/frame_counting.rs#L9-L37)
used in several structs which rely on those derives (or otherwise the
higher-level structs would have to implement these traits manually).
That crate, using `FrameCount`, tracks input frames and timestamps and
enables various playback modes.

I am aware that bevy org refrains from deriving lots of unnecessary
stuff on bevy types to avoid compile time creep. It is worth mentioning
the (equally reasonable) alternative that downstream crates _should_
implement some `FrameCount` themselves if they want special behavior
from it.

## Solution

- **Describe the solution used to achieve the objective above.**

I added derives for `PartialEq, Eq, PartialOrd, Ord` and implementations
for `serde::{Deserialize, Serialize}` to `FrameCount`.

## Testing

Manually confirmed that the serde implementation works, but that's all.
Let me know if I should do more here.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-05-10 10:00:08 +00:00

92 lines
2.2 KiB
Rust

use std::{
any,
fmt::{self, Formatter},
};
use serde::{
de::{Error, Visitor},
Deserialize, Deserializer, Serialize, Serializer,
};
use super::name::Name;
use super::FrameCount;
impl Serialize for Name {
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
serializer.serialize_str(self.as_str())
}
}
impl<'de> Deserialize<'de> for Name {
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
deserializer.deserialize_str(EntityVisitor)
}
}
struct EntityVisitor;
impl<'de> Visitor<'de> for EntityVisitor {
type Value = Name;
fn expecting(&self, formatter: &mut Formatter) -> fmt::Result {
formatter.write_str(any::type_name::<Name>())
}
fn visit_str<E: Error>(self, v: &str) -> Result<Self::Value, E> {
Ok(Name::new(v.to_string()))
}
fn visit_string<E: Error>(self, v: String) -> Result<Self::Value, E> {
Ok(Name::new(v))
}
}
// Manually implementing serialize/deserialize allows us to use a more compact representation as simple integers
impl Serialize for FrameCount {
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
serializer.serialize_u32(self.0)
}
}
impl<'de> Deserialize<'de> for FrameCount {
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
deserializer.deserialize_u32(FrameVisitor)
}
}
struct FrameVisitor;
impl<'de> Visitor<'de> for FrameVisitor {
type Value = FrameCount;
fn expecting(&self, formatter: &mut Formatter) -> fmt::Result {
formatter.write_str(any::type_name::<FrameCount>())
}
fn visit_u32<E>(self, v: u32) -> Result<Self::Value, E>
where
E: Error,
{
Ok(FrameCount(v))
}
}
#[cfg(test)]
mod tests {
use super::*;
use serde_test::{assert_tokens, Token};
#[test]
fn test_serde_name() {
let name = Name::new("MyComponent");
assert_tokens(&name, &[Token::String("MyComponent")]);
}
#[test]
fn test_serde_frame_count() {
let frame_count = FrameCount(100);
assert_tokens(&frame_count, &[Token::U32(100)]);
}
}