1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669
//! This crate contains macros used by Bevy's `Reflect` API.
//!
//! The main export of this crate is the derive macro for [`Reflect`]. This allows
//! types to easily implement `Reflect` along with other `bevy_reflect` traits,
//! such as `Struct`, `GetTypeRegistration`, and more— all with a single derive!
//!
//! Some other noteworthy exports include the derive macros for [`FromReflect`] and
//! [`TypePath`], as well as the [`reflect_trait`] attribute macro.
//!
//! [`Reflect`]: crate::derive_reflect
//! [`FromReflect`]: crate::derive_from_reflect
//! [`TypePath`]: crate::derive_type_path
//! [`reflect_trait`]: macro@reflect_trait
extern crate proc_macro;
mod container_attributes;
mod derive_data;
#[cfg(feature = "documentation")]
mod documentation;
mod enum_utility;
mod field_attributes;
mod from_reflect;
mod impls;
mod reflect_value;
mod registration;
mod serialization;
mod trait_reflection;
mod type_path;
mod utility;
use crate::derive_data::{ReflectDerive, ReflectMeta, ReflectStruct};
use container_attributes::ContainerAttributes;
use derive_data::{ReflectImplSource, ReflectProvenance, ReflectTraitToImpl, ReflectTypePath};
use proc_macro::TokenStream;
use quote::quote;
use reflect_value::ReflectValueDef;
use syn::{parse_macro_input, DeriveInput};
use type_path::NamedTypePathDef;
pub(crate) static REFLECT_ATTRIBUTE_NAME: &str = "reflect";
pub(crate) static REFLECT_VALUE_ATTRIBUTE_NAME: &str = "reflect_value";
pub(crate) static TYPE_PATH_ATTRIBUTE_NAME: &str = "type_path";
pub(crate) static TYPE_NAME_ATTRIBUTE_NAME: &str = "type_name";
/// Used both for [`impl_reflect`] and [`derive_reflect`].
///
/// [`impl_reflect`]: macro@impl_reflect
/// [`derive_reflect`]: derive_reflect()
fn match_reflect_impls(ast: DeriveInput, source: ReflectImplSource) -> TokenStream {
let derive_data = match ReflectDerive::from_input(
&ast,
ReflectProvenance {
source,
trait_: ReflectTraitToImpl::Reflect,
},
) {
Ok(data) => data,
Err(err) => return err.into_compile_error().into(),
};
let (reflect_impls, from_reflect_impl) = match derive_data {
ReflectDerive::Struct(struct_data) | ReflectDerive::UnitStruct(struct_data) => (
impls::impl_struct(&struct_data),
if struct_data.meta().from_reflect().should_auto_derive() {
Some(from_reflect::impl_struct(&struct_data))
} else {
None
},
),
ReflectDerive::TupleStruct(struct_data) => (
impls::impl_tuple_struct(&struct_data),
if struct_data.meta().from_reflect().should_auto_derive() {
Some(from_reflect::impl_tuple_struct(&struct_data))
} else {
None
},
),
ReflectDerive::Enum(enum_data) => (
impls::impl_enum(&enum_data),
if enum_data.meta().from_reflect().should_auto_derive() {
Some(from_reflect::impl_enum(&enum_data))
} else {
None
},
),
ReflectDerive::Value(meta) => (
impls::impl_value(&meta),
if meta.from_reflect().should_auto_derive() {
Some(from_reflect::impl_value(&meta))
} else {
None
},
),
};
TokenStream::from(quote! {
const _: () = {
#reflect_impls
#from_reflect_impl
};
})
}
/// The main derive macro used by `bevy_reflect` for deriving its `Reflect` trait.
///
/// This macro can be used on all structs and enums (unions are not supported).
/// It will automatically generate implementations for `Reflect`, `Typed`, `GetTypeRegistration`, and `FromReflect`.
/// And, depending on the item's structure, will either implement `Struct`, `TupleStruct`, or `Enum`.
///
/// See the [`FromReflect`] derive macro for more information on how to customize the `FromReflect` implementation.
///
/// # Container Attributes
///
/// This macro comes with some helper attributes that can be added to the container item
/// in order to provide additional functionality or alter the generated implementations.
///
/// In addition to those listed, this macro can also use the attributes for [`TypePath`] derives.
///
/// ## `#[reflect(Ident)]`
///
/// The `#[reflect(Ident)]` attribute is used to add type data registrations to the `GetTypeRegistration`
/// implementation corresponding to the given identifier, prepended by `Reflect`.
///
/// For example, `#[reflect(Foo, Bar)]` would add two registrations:
/// one for `ReflectFoo` and another for `ReflectBar`.
/// This assumes these types are indeed in-scope wherever this macro is called.
///
/// This is often used with traits that have been marked by the [`#[reflect_trait]`](macro@reflect_trait)
/// macro in order to register the type's implementation of that trait.
///
/// ### Default Registrations
///
/// The following types are automatically registered when deriving `Reflect`:
///
/// * `ReflectFromReflect` (unless opting out of `FromReflect`)
/// * `SerializationData`
/// * `ReflectFromPtr`
///
/// ### Special Identifiers
///
/// There are a few "special" identifiers that work a bit differently:
///
/// * `#[reflect(Debug)]` will force the implementation of `Reflect::reflect_debug` to rely on
/// the type's [`Debug`] implementation.
/// A custom implementation may be provided using `#[reflect(Debug(my_debug_func))]` where
/// `my_debug_func` is the path to a function matching the signature:
/// `(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result`.
/// * `#[reflect(PartialEq)]` will force the implementation of `Reflect::reflect_partial_eq` to rely on
/// the type's [`PartialEq`] implementation.
/// A custom implementation may be provided using `#[reflect(PartialEq(my_partial_eq_func))]` where
/// `my_partial_eq_func` is the path to a function matching the signature:
/// `(&self, value: &dyn #bevy_reflect_path::Reflect) -> bool`.
/// * `#[reflect(Hash)]` will force the implementation of `Reflect::reflect_hash` to rely on
/// the type's [`Hash`] implementation.
/// A custom implementation may be provided using `#[reflect(Hash(my_hash_func))]` where
/// `my_hash_func` is the path to a function matching the signature: `(&self) -> u64`.
/// * `#[reflect(Default)]` will register the `ReflectDefault` type data as normal.
/// However, it will also affect how certain other operations are performed in order
/// to improve performance and/or robustness.
/// An example of where this is used is in the [`FromReflect`] derive macro,
/// where adding this attribute will cause the `FromReflect` implementation to create
/// a base value using its [`Default`] implementation avoiding issues with ignored fields
/// (for structs and tuple structs only).
///
/// ## `#[reflect_value]`
///
/// The `#[reflect_value]` attribute (which may also take the form `#[reflect_value(Ident)]`),
/// denotes that the item should implement `Reflect` as though it were a base value type.
/// This means that it will forgo implementing `Struct`, `TupleStruct`, or `Enum`.
///
/// Furthermore, it requires that the type implements [`Clone`].
/// If planning to serialize this type using the reflection serializers,
/// then the `Serialize` and `Deserialize` traits will need to be implemented and registered as well.
///
/// ## `#[reflect(from_reflect = false)]`
///
/// This attribute will opt-out of the default `FromReflect` implementation.
///
/// This is useful for when a type can't or shouldn't implement `FromReflect`,
/// or if a manual implementation is desired.
///
/// Note that in the latter case, `ReflectFromReflect` will no longer be automatically registered.
///
/// ## `#[reflect(type_path = false)]`
///
/// This attribute will opt-out of the default `TypePath` implementation.
///
/// This is useful for when a type can't or shouldn't implement `TypePath`,
/// or if a manual implementation is desired.
///
/// ## `#[reflect(no_field_bounds)]`
///
/// This attribute will opt-out of the default trait bounds added to all field types
/// for the generated reflection trait impls.
///
/// Normally, all fields will have the bounds `TypePath`, and either `FromReflect` or `Reflect`
/// depending on if `#[reflect(from_reflect = false)]` is used.
/// However, this might not always be desirable, and so this attribute may be used to remove those bounds.
///
/// ### Example
///
/// If a type is recursive the default bounds will cause an overflow error when building:
///
/// ```ignore (bevy_reflect is not accessible from this crate)
/// #[derive(Reflect)] // ERROR: overflow evaluating the requirement `Foo: FromReflect`
/// struct Foo {
/// foo: Vec<Foo>,
/// }
///
/// // Generates a where clause like:
/// // impl bevy_reflect::Reflect for Foo
/// // where
/// // Self: Any + Send + Sync,
/// // Vec<Foo>: FromReflect + TypePath,
/// ```
///
/// In this case, `Foo` is given the bounds `Vec<Foo>: FromReflect + TypePath`,
/// which requires that `Foo` implements `FromReflect`,
/// which requires that `Vec<Foo>` implements `FromReflect`,
/// and so on, resulting in the error.
///
/// To fix this, we can add `#[reflect(no_field_bounds)]` to `Foo` to remove the bounds on `Vec<Foo>`:
///
/// ```ignore (bevy_reflect is not accessible from this crate)
/// #[derive(Reflect)]
/// #[reflect(no_field_bounds)]
/// struct Foo {
/// foo: Vec<Foo>,
/// }
///
/// // Generates a where clause like:
/// // impl bevy_reflect::Reflect for Foo
/// // where
/// // Self: Any + Send + Sync,
/// ```
///
/// ## `#[reflect(where T: Trait, U::Assoc: Trait, ...)]`
///
/// This attribute can be used to add additional bounds to the generated reflection trait impls.
///
/// This is useful for when a type needs certain bounds only applied to the reflection impls
/// that are not otherwise automatically added by the derive macro.
///
/// ### Example
///
/// In the example below, we want to enforce that `T::Assoc: List` is required in order for
/// `Foo<T>` to be reflectable, but we don't want it to prevent `Foo<T>` from being used
/// in places where `T::Assoc: List` is not required.
///
/// ```ignore
/// trait Trait {
/// type Assoc;
/// }
///
/// #[derive(Reflect)]
/// #[reflect(where T::Assoc: List)]
/// struct Foo<T: Trait> where T::Assoc: Default {
/// value: T::Assoc,
/// }
///
/// // Generates a where clause like:
/// //
/// // impl<T: Trait> bevy_reflect::Reflect for Foo<T>
/// // where
/// // Self: Any + Send + Sync,
/// // T::Assoc: Default,
/// // T: TypePath,
/// // T::Assoc: FromReflect + TypePath,
/// // T::Assoc: List,
/// // {/* ... */}
/// ```
///
/// # Field Attributes
///
/// Along with the container attributes, this macro comes with some attributes that may be applied
/// to the contained fields themselves.
///
/// ## `#[reflect(ignore)]`
///
/// This attribute simply marks a field to be ignored by the reflection API.
///
/// This allows fields to completely opt-out of reflection,
/// which may be useful for maintaining invariants, keeping certain data private,
/// or allowing the use of types that do not implement `Reflect` within the container.
///
/// ## `#[reflect(skip_serializing)]`
///
/// This works similar to `#[reflect(ignore)]`, but rather than opting out of _all_ of reflection,
/// it simply opts the field out of both serialization and deserialization.
/// This can be useful when a field should be accessible via reflection, but may not make
/// sense in a serialized form, such as computed data.
///
/// What this does is register the `SerializationData` type within the `GetTypeRegistration` implementation,
/// which will be used by the reflection serializers to determine whether or not the field is serializable.
///
/// [`reflect_trait`]: macro@reflect_trait
#[proc_macro_derive(Reflect, attributes(reflect, reflect_value, type_path, type_name))]
pub fn derive_reflect(input: TokenStream) -> TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
match_reflect_impls(ast, ReflectImplSource::DeriveLocalType)
}
/// Derives the `FromReflect` trait.
///
/// # Field Attributes
///
/// ## `#[reflect(ignore)]`
///
/// The `#[reflect(ignore)]` attribute is shared with the [`#[derive(Reflect)]`](Reflect) macro and has much of the same
/// functionality in that it denotes that a field will be ignored by the reflection API.
///
/// The only major difference is that using it with this derive requires that the field implements [`Default`].
/// Without this requirement, there would be no way for `FromReflect` to automatically construct missing fields
/// that have been ignored.
///
/// ## `#[reflect(default)]`
///
/// If a field cannot be read, this attribute specifies a default value to be used in its place.
///
/// By default, this attribute denotes that the field's type implements [`Default`].
/// However, it can also take in a path string to a user-defined function that will return the default value.
/// This takes the form: `#[reflect(default = "path::to::my_function")]` where `my_function` is a parameterless
/// function that must return some default value for the type.
///
/// Specifying a custom default can be used to give different fields their own specialized defaults,
/// or to remove the `Default` requirement on fields marked with `#[reflect(ignore)]`.
/// Additionally, either form of this attribute can be used to fill in fields that are simply missing,
/// such as when converting a partially-constructed dynamic type to a concrete one.
#[proc_macro_derive(FromReflect, attributes(reflect))]
pub fn derive_from_reflect(input: TokenStream) -> TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
let derive_data = match ReflectDerive::from_input(
&ast,
ReflectProvenance {
source: ReflectImplSource::DeriveLocalType,
trait_: ReflectTraitToImpl::FromReflect,
},
) {
Ok(data) => data,
Err(err) => return err.into_compile_error().into(),
};
let from_reflect_impl = match derive_data {
ReflectDerive::Struct(struct_data) | ReflectDerive::UnitStruct(struct_data) => {
from_reflect::impl_struct(&struct_data)
}
ReflectDerive::TupleStruct(struct_data) => from_reflect::impl_tuple_struct(&struct_data),
ReflectDerive::Enum(meta) => from_reflect::impl_enum(&meta),
ReflectDerive::Value(meta) => from_reflect::impl_value(&meta),
};
TokenStream::from(quote! {
const _: () = {
#from_reflect_impl
};
})
}
/// Derives the `TypePath` trait, providing a stable alternative to [`std::any::type_name`].
///
/// # Container Attributes
///
/// ## `#[type_path = "my_crate::foo"]`
///
/// Optionally specifies a custom module path to use instead of [`module_path`].
///
/// This path does not include the final identifier.
///
/// ## `#[type_name = "RenamedType"]`
///
/// Optionally specifies a new terminating identifier for `TypePath`.
///
/// To use this attribute, `#[type_path = "..."]` must also be specified.
#[proc_macro_derive(TypePath, attributes(type_path, type_name))]
pub fn derive_type_path(input: TokenStream) -> TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
let derive_data = match ReflectDerive::from_input(
&ast,
ReflectProvenance {
source: ReflectImplSource::DeriveLocalType,
trait_: ReflectTraitToImpl::TypePath,
},
) {
Ok(data) => data,
Err(err) => return err.into_compile_error().into(),
};
let type_path_impl = impls::impl_type_path(derive_data.meta());
TokenStream::from(quote! {
const _: () = {
#type_path_impl
};
})
}
/// A macro that automatically generates type data for traits, which their implementors can then register.
///
/// The output of this macro is a struct that takes reflected instances of the implementor's type
/// and returns the value as a trait object.
/// Because of this, **it can only be used on [object-safe] traits.**
///
/// For a trait named `MyTrait`, this will generate the struct `ReflectMyTrait`.
/// The generated struct can be created using `FromType` with any type that implements the trait.
/// The creation and registration of this generated struct as type data can be automatically handled
/// by [`#[derive(Reflect)]`](Reflect).
///
/// # Example
///
/// ```ignore (bevy_reflect is not accessible from this crate)
/// # use std::any::TypeId;
/// # use bevy_reflect_derive::{Reflect, reflect_trait};
/// #[reflect_trait] // Generates `ReflectMyTrait`
/// trait MyTrait {
/// fn print(&self) -> &str;
/// }
///
/// #[derive(Reflect)]
/// #[reflect(MyTrait)] // Automatically registers `ReflectMyTrait`
/// struct SomeStruct;
///
/// impl MyTrait for SomeStruct {
/// fn print(&self) -> &str {
/// "Hello, World!"
/// }
/// }
///
/// // We can create the type data manually if we wanted:
/// let my_trait: ReflectMyTrait = FromType::<SomeStruct>::from_type();
///
/// // Or we can simply get it from the registry:
/// let mut registry = TypeRegistry::default();
/// registry.register::<SomeStruct>();
/// let my_trait = registry
/// .get_type_data::<ReflectMyTrait>(TypeId::of::<SomeStruct>())
/// .unwrap();
///
/// // Then use it on reflected data
/// let reflected: Box<dyn Reflect> = Box::new(SomeStruct);
/// let reflected_my_trait: &dyn MyTrait = my_trait.get(&*reflected).unwrap();
/// assert_eq!("Hello, World!", reflected_my_trait.print());
/// ```
///
/// [object-safe]: https://doc.rust-lang.org/reference/items/traits.html#object-safety
#[proc_macro_attribute]
pub fn reflect_trait(args: TokenStream, input: TokenStream) -> TokenStream {
trait_reflection::reflect_trait(&args, input)
}
/// A macro used to generate reflection trait implementations for the given type.
///
/// This is functionally the same as [deriving `Reflect`] using the `#[reflect_value]` container attribute.
///
/// The only reason for this macro's existence is so that `bevy_reflect` can easily implement the reflection traits
/// on primitives and other Rust types internally.
///
/// Since this macro also implements `TypePath`, the type path must be explicit.
/// See [`impl_type_path!`] for the exact syntax.
///
/// # Examples
///
/// Types can be passed with or without registering type data:
///
/// ```ignore (bevy_reflect is not accessible from this crate)
/// impl_reflect_value!(my_crate::Foo);
/// impl_reflect_value!(my_crate::Bar(Debug, Default, Serialize, Deserialize));
/// ```
///
/// Generic types can also specify their parameters and bounds:
///
/// ```ignore (bevy_reflect is not accessible from this crate)
/// impl_reflect_value!(my_crate::Foo<T1, T2: Baz> where T1: Bar (Default, Serialize, Deserialize));
/// ```
///
/// Custom type paths can be specified:
///
/// ```ignore (bevy_reflect is not accessible from this crate)
/// impl_reflect_value!((in not_my_crate as NotFoo) Foo(Debug, Default));
/// ```
///
/// [deriving `Reflect`]: Reflect
#[proc_macro]
pub fn impl_reflect_value(input: TokenStream) -> TokenStream {
let def = parse_macro_input!(input with ReflectValueDef::parse_reflect);
let default_name = &def.type_path.segments.last().unwrap().ident;
let type_path = if def.type_path.leading_colon.is_none() && def.custom_path.is_none() {
ReflectTypePath::Primitive(default_name)
} else {
ReflectTypePath::External {
path: &def.type_path,
custom_path: def.custom_path.map(|path| path.into_path(default_name)),
generics: &def.generics,
}
};
let meta = ReflectMeta::new(type_path, def.traits.unwrap_or_default());
#[cfg(feature = "documentation")]
let meta = meta.with_docs(documentation::Documentation::from_attributes(&def.attrs));
let reflect_impls = impls::impl_value(&meta);
let from_reflect_impl = from_reflect::impl_value(&meta);
TokenStream::from(quote! {
const _: () = {
#reflect_impls
#from_reflect_impl
};
})
}
/// A replacement for `#[derive(Reflect)]` to be used with foreign types which
/// the definitions of cannot be altered.
///
/// This macro is an alternative to [`impl_reflect_value!`] and [`impl_from_reflect_value!`]
/// which implement foreign types as Value types. Note that there is no `impl_from_reflect`,
/// as this macro will do the job of both. This macro implements them using one of the reflect
/// variant traits (`bevy_reflect::{Struct, TupleStruct, Enum}`, etc.),
/// which have greater functionality. The type being reflected must be in scope, as you cannot
/// qualify it in the macro as e.g. `bevy::prelude::Vec3`.
///
/// It is necessary to add a `#[type_path = "my_crate::foo"]` attribute to all types.
///
/// It may be necessary to add `#[reflect(Default)]` for some types, specifically non-constructible
/// foreign types. Without `Default` reflected for such types, you will usually get an arcane
/// error message and fail to compile. If the type does not implement `Default`, it may not
/// be possible to reflect without extending the macro.
///
///
/// # Example
/// Implementing `Reflect` for `bevy::prelude::Vec3` as a struct type:
/// ```ignore (bevy_reflect is not accessible from this crate)
/// use bevy::prelude::Vec3;
///
/// impl_reflect!(
/// #[reflect(PartialEq, Serialize, Deserialize, Default)]
/// #[type_path = "bevy::prelude"]
/// struct Vec3 {
/// x: f32,
/// y: f32,
/// z: f32
/// }
/// );
/// ```
#[proc_macro]
pub fn impl_reflect(input: TokenStream) -> TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
match_reflect_impls(ast, ReflectImplSource::ImplRemoteType)
}
/// A macro used to generate a `FromReflect` trait implementation for the given type.
///
/// This is functionally the same as [deriving `FromReflect`] on a type that [derives `Reflect`] using
/// the `#[reflect_value]` container attribute.
///
/// The only reason this macro exists is so that `bevy_reflect` can easily implement `FromReflect` on
/// primitives and other Rust types internally.
///
/// Please note that this macro will not work with any type that [derives `Reflect`] normally
/// or makes use of the [`impl_reflect_value!`] macro, as those macros also implement `FromReflect`
/// by default.
///
/// # Examples
///
/// ```ignore (bevy_reflect is not accessible from this crate)
/// impl_from_reflect_value!(foo<T1, T2: Baz> where T1: Bar);
/// ```
///
/// [deriving `FromReflect`]: FromReflect
/// [derives `Reflect`]: Reflect
#[proc_macro]
pub fn impl_from_reflect_value(input: TokenStream) -> TokenStream {
let def = parse_macro_input!(input with ReflectValueDef::parse_from_reflect);
let default_name = &def.type_path.segments.last().unwrap().ident;
let type_path = if def.type_path.leading_colon.is_none()
&& def.custom_path.is_none()
&& def.generics.params.is_empty()
{
ReflectTypePath::Primitive(default_name)
} else {
ReflectTypePath::External {
path: &def.type_path,
custom_path: def.custom_path.map(|alias| alias.into_path(default_name)),
generics: &def.generics,
}
};
let from_reflect_impl =
from_reflect::impl_value(&ReflectMeta::new(type_path, def.traits.unwrap_or_default()));
TokenStream::from(quote! {
const _: () = {
#from_reflect_impl
};
})
}
/// A replacement for [deriving `TypePath`] for use on foreign types.
///
/// Since (unlike the derive) this macro may be invoked in a different module to where the type is defined,
/// it requires an 'absolute' path definition.
///
/// Specifically, a leading `::` denoting a global path must be specified
/// or a preceding `(in my_crate::foo)` to specify the custom path must be used.
///
/// # Examples
///
/// Implementing `TypePath` on a foreign type:
/// ```ignore (bevy_reflect is not accessible from this crate)
/// impl_type_path!(::foreign_crate::foo::bar::Baz);
/// ```
///
/// On a generic type (this can also accept trait bounds):
/// ```ignore (bevy_reflect is not accessible from this crate)
/// impl_type_path!(::foreign_crate::Foo<T>);
/// impl_type_path!(::foreign_crate::Goo<T: ?Sized>);
/// ```
///
/// On a primitive (note this will not compile for a non-primitive type):
/// ```ignore (bevy_reflect is not accessible from this crate)
/// impl_type_path!(bool);
/// ```
///
/// With a custom type path:
/// ```ignore (bevy_reflect is not accessible from this crate)
/// impl_type_path!((in other_crate::foo::bar) Baz);
/// ```
///
/// With a custom type path and a custom type name:
/// ```ignore (bevy_reflect is not accessible from this crate)
/// impl_type_path!((in other_crate::foo as Baz) Bar);
/// ```
///
/// [deriving `TypePath`]: TypePath
#[proc_macro]
pub fn impl_type_path(input: TokenStream) -> TokenStream {
let def = parse_macro_input!(input as NamedTypePathDef);
let type_path = match def {
NamedTypePathDef::External {
ref path,
custom_path,
ref generics,
} => {
let default_name = &path.segments.last().unwrap().ident;
ReflectTypePath::External {
path,
custom_path: custom_path.map(|path| path.into_path(default_name)),
generics,
}
}
NamedTypePathDef::Primitive(ref ident) => ReflectTypePath::Primitive(ident),
};
let meta = ReflectMeta::new(type_path, ContainerAttributes::default());
let type_path_impl = impls::impl_type_path(&meta);
TokenStream::from(quote! {
const _: () = {
#type_path_impl
};
})
}