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//! [`ReflectDsl`] and helper types.
//!
//! Instead of using [`ParseDsl`]
use std::{any::type_name, convert::Infallible, fmt, marker::PhantomData};
use anyhow::Result;
use bevy::ecs::prelude::Bundle;
use bevy::prelude::{Deref, DerefMut};
use bevy::reflect::erased_serde::__private::serde::de::DeserializeSeed;
use bevy::reflect::{serde::TypedReflectDeserializer, Reflect, Struct};
use cuicui_dsl::DslBundle;
use thiserror::Error;
use crate::parse_dsl::{MethodCtx, ParseDsl};
/// Occurs in [`ReflectDsl::typed_method`].
#[derive(Error)]
enum ReflectDslError<T> {
#[error(
"Method on `ReflectDsl` was called with not exactly one argument. \
Try having double parenthesis around the method argument"
)]
NotExactlyOneArgument,
#[error(
"Tried to set the field '{0}' of ReflectDsl<{ty}>, but {ty} \
doesn't have such a field",
ty=type_name::<T>()
)]
BadField(String),
#[error(
"The field {path} of '{ty}' is not registered. \
Please register the type '{missing}' to be able to use ReflectDsl<{ty}>.",
ty=type_name::<T>(),
)]
NotRegistered { path: String, missing: String },
#[error("Failed to deserialize ReflectDsl<{}>: {0}", type_name::<T>())]
BadDeser(anyhow::Error),
#[error("This error never happens")]
_Ignonre(PhantomData<fn(T)>, Infallible),
}
impl<T> fmt::Debug for ReflectDslError<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
use ReflectDslError::{BadDeser, BadField, NotRegistered, _Ignonre};
match self {
BadField(field) => f.debug_tuple("BadField").field(field).finish(),
NotRegistered { path, missing } => f
.debug_struct("NotRegistered")
.field("path", path)
.field("missing", missing)
.finish(),
BadDeser(error) => f.debug_tuple("BadDeser").field(error).finish(),
Self::NotExactlyOneArgument => write!(f, "NotExactlyOneArgument"),
_Ignonre(..) => unreachable!(),
}
}
}
/// A `serde` deserializer used to parse some `input` into a `Box<dyn Reflect>`.
///
/// This is used in [`ReflectDsl`] to deserialize method arguments (`T`'s field values).
/// A default implementation is provided with [`RonFormat`].
pub trait Format {
/// Deserialize into a `Box<dyn Reflect>`, any error is propagated by [`ReflectDsl::method`].
#[allow(clippy::missing_errors_doc)] // false+: We can't say what our users will fail with.
fn deserialize(input: &[u8], de: TypedReflectDeserializer) -> Result<Box<dyn Reflect>>;
}
/// Deserialize method arguments as `ron` strings.
///
/// This is the default deserialization method for [`ReflectDsl`].
pub struct RonFormat;
impl Format for RonFormat {
fn deserialize(input: &[u8], de: TypedReflectDeserializer) -> Result<Box<dyn Reflect>> {
Ok(de.deserialize(&mut ron::de::Deserializer::from_bytes(input)?)?)
}
}
/// Automatic [`ParseDsl`] implementation for any [`Bundle`] + [`Reflect`] `struct`.
///
/// If you find using the `parse_dsl_impl` macro burdensome, and just want to
/// use any bevy `Bundle` as a DSL, you can use `ReflectDsl` to use the `struct`
/// fields as DSL "methods", and [`Reflect` deserialization][refl-deser] to parse
/// the arguments automatically.
///
/// # How to use
///
/// You have a type as follow:
/// ```no_run
/// use cuicui_chirp::ReflectDsl;
/// # use bevy::prelude::*;
///
/// #[derive(Bundle, Reflect, Default)]
/// struct MyBundle {
/// transform: Transform,
/// visibility: Visibility,
/// }
/// # let mut app = App::new();
/// // and you did register it with:
/// app.register_type::<MyBundle>();
/// ```
/// You want to use it in a DSL when parsing files. Consider the following
/// `chirp` file:
/// ```text
/// entity(row) {
/// entity (
/// transform (
/// translation: (x: 0.0, y: 0.0, z: 0.0),
/// rotation: (0.0, 0.0, 0.0, 1.0),
/// scale: (x: 1.0, y: 1.0, z: 1.0),
/// ),
/// visibility Inherited,
/// );
/// }
/// ```
/// You want both `LayoutDsl` methods and fields of `MyBundle` to work in your
/// chirp files.
///
/// In order to do that, you should add the loader for the correct DSL as follow:
/// ```no_run
/// use cuicui_chirp::ReflectDsl;
/// # use bevy::prelude::*;
///
/// # type LayoutDsl = ();
/// # #[derive(Bundle, Reflect, Default)] struct MyBundle { transform: Transform, visibility: Visibility }
/// // Add `ReflectDsl<MyBundle, _>` as an extension on the `LayoutDsl` DSL.
/// type Dsl = ReflectDsl<MyBundle, LayoutDsl>;
/// # let mut app = App::new();
/// app.add_plugins((
/// # bevy::asset::AssetPlugin::default(),
/// // ...
/// // The loader now recognizes the methods `transform` and `visibility`.
/// // They were fields of `MyBundle`
/// cuicui_chirp::loader::Plugin::new::<Dsl>(),
/// ));
/// ```
///
/// # Caveats
///
/// This doesn't work with the `dsl!` macro. You can only use `ReflectDsl` with
/// scenes defined in `chirp` files.
///
/// [refl-deser]: https://docs.rs/bevy_reflect/latest/bevy_reflect/#serialization
#[derive(Debug, Clone, Deref, DerefMut)]
pub struct ReflectDsl<T: Struct, D: DslBundle = (), F: Format = RonFormat> {
inner: Option<T>,
#[deref]
delegate_dsl: D,
_format: PhantomData<F>,
}
impl<T: Default + Struct, D: DslBundle, F: Format> Default for ReflectDsl<T, D, F> {
fn default() -> Self {
Self {
inner: Some(T::default()),
delegate_dsl: D::default(),
_format: PhantomData,
}
}
}
impl<T, D, F> DslBundle for ReflectDsl<T, D, F>
where
T: Bundle + Default + Struct,
D: DslBundle,
F: Format,
{
fn insert(&mut self, cmds: &mut cuicui_dsl::EntityCommands) {
// unwrap: This `Self::default` in `Some` state, and only becomes `None` when `insert`
// is called. Since it is only called once, it is fine to unwrap.
cmds.insert(self.inner.take().unwrap());
self.delegate_dsl.insert(cmds);
}
}
impl<T, D, F> ReflectDsl<T, D, F>
where
T: Bundle + Default + Struct,
D: DslBundle,
F: Format,
{
/// This is just so the error type is easier to convert in the `ParseDsl::method` impl.
#[allow(deprecated)]
fn typed_method(&mut self, ctx: &MethodCtx) -> Result<(), ReflectDslError<T>> {
use ReflectDslError::{BadDeser, BadField};
// unwrap: Same logic as in `DslBundle::insert`
let inner = self.inner.as_mut().unwrap();
if ctx.arguments.len() != 1 {
return Err(ReflectDslError::NotExactlyOneArgument);
}
let argument = ctx.arguments.get(0).unwrap();
let Some(field_to_update) = inner.field_mut(ctx.name) else {
return Err(BadField(ctx.name.to_string()));
};
let id = field_to_update.type_id();
let not_registered = || ReflectDslError::NotRegistered {
path: ctx.name.to_string(),
missing: field_to_update.type_name().to_string(),
};
let registration = ctx.registry.get(id).ok_or_else(not_registered)?;
let de = TypedReflectDeserializer::new(registration, ctx.registry);
let field_value = F::deserialize(&argument, de).map_err(BadDeser)?;
// unwrap: Error should never happen, since we get the registration for field.
field_to_update.set(field_value).unwrap();
Ok(())
}
}
impl<T, D, F> ParseDsl for ReflectDsl<T, D, F>
where
T: Bundle + Default + Struct,
D: DslBundle,
F: Format,
{
fn method(&mut self, ctx: MethodCtx) -> Result<()> {
Ok(self.typed_method(&ctx)?)
}
}