bevy_reflect/path/
mod.rs

1pub mod access;
2pub use access::*;
3
4mod error;
5pub use error::*;
6
7mod parse;
8pub use parse::ParseError;
9use parse::PathParser;
10
11use crate::{PartialReflect, Reflect};
12use alloc::vec::Vec;
13use core::fmt;
14use derive_more::derive::From;
15use thiserror::Error;
16
17type PathResult<'a, T> = Result<T, ReflectPathError<'a>>;
18
19/// An error returned from a failed path string query.
20#[derive(Error, Debug, PartialEq, Eq)]
21pub enum ReflectPathError<'a> {
22    /// An error caused by trying to access a path that's not able to be accessed,
23    /// see [`AccessError`] for details.
24    #[error(transparent)]
25    InvalidAccess(AccessError<'a>),
26
27    /// An error that occurs when a type cannot downcast to a given type.
28    #[error("Can't downcast result of access to the given type")]
29    InvalidDowncast,
30
31    /// An error caused by an invalid path string that couldn't be parsed.
32    #[error("Encountered an error at offset {offset} while parsing `{path}`: {error}")]
33    ParseError {
34        /// Position in `path`.
35        offset: usize,
36        /// The path that the error occurred in.
37        path: &'a str,
38        /// The underlying error.
39        error: ParseError<'a>,
40    },
41}
42
43impl<'a> From<AccessError<'a>> for ReflectPathError<'a> {
44    fn from(value: AccessError<'a>) -> Self {
45        ReflectPathError::InvalidAccess(value)
46    }
47}
48
49/// Something that can be interpreted as a reflection path in [`GetPath`].
50pub trait ReflectPath<'a>: Sized {
51    /// Gets a reference to the specified element on the given [`Reflect`] object.
52    ///
53    /// See [`GetPath::reflect_path`] for more details,
54    /// see [`element`](Self::element) if you want a typed return value.
55    fn reflect_element(self, root: &dyn PartialReflect) -> PathResult<'a, &dyn PartialReflect>;
56
57    /// Gets a mutable reference to the specified element on the given [`Reflect`] object.
58    ///
59    /// See [`GetPath::reflect_path_mut`] for more details.
60    fn reflect_element_mut(
61        self,
62        root: &mut dyn PartialReflect,
63    ) -> PathResult<'a, &mut dyn PartialReflect>;
64
65    /// Gets a `&T` to the specified element on the given [`Reflect`] object.
66    ///
67    /// See [`GetPath::path`] for more details.
68    fn element<T: Reflect>(self, root: &dyn PartialReflect) -> PathResult<'a, &T> {
69        self.reflect_element(root).and_then(|p| {
70            p.try_downcast_ref::<T>()
71                .ok_or(ReflectPathError::InvalidDowncast)
72        })
73    }
74
75    /// Gets a `&mut T` to the specified element on the given [`Reflect`] object.
76    ///
77    /// See [`GetPath::path_mut`] for more details.
78    fn element_mut<T: Reflect>(self, root: &mut dyn PartialReflect) -> PathResult<'a, &mut T> {
79        self.reflect_element_mut(root).and_then(|p| {
80            p.try_downcast_mut::<T>()
81                .ok_or(ReflectPathError::InvalidDowncast)
82        })
83    }
84}
85
86impl<'a> ReflectPath<'a> for &'a str {
87    fn reflect_element(self, mut root: &dyn PartialReflect) -> PathResult<'a, &dyn PartialReflect> {
88        for (access, offset) in PathParser::new(self) {
89            let a = access?;
90            root = a.element(root, Some(offset))?;
91        }
92        Ok(root)
93    }
94    fn reflect_element_mut(
95        self,
96        mut root: &mut dyn PartialReflect,
97    ) -> PathResult<'a, &mut dyn PartialReflect> {
98        for (access, offset) in PathParser::new(self) {
99            root = access?.element_mut(root, Some(offset))?;
100        }
101        Ok(root)
102    }
103}
104/// A trait which allows nested [`Reflect`] values to be retrieved with path strings.
105///
106/// Using these functions repeatedly with the same string requires parsing the string every time.
107/// To avoid this cost, it's recommended to construct a [`ParsedPath`] instead.
108///
109/// # Syntax
110///
111/// ## Structs
112///
113/// Field paths for [`Struct`] elements use the standard Rust field access syntax of
114/// dot and field name: `.field_name`.
115///
116/// Additionally, struct fields may be accessed by their index within the struct's definition.
117/// This is accomplished by using the hash symbol (`#`) in place of the standard dot: `#0`.
118///
119/// Accessing a struct's field by index can speed up fetches at runtime due to the removed
120/// need for string matching.
121/// And while this can be more performant, it's best to keep in mind the tradeoffs when
122/// utilizing such optimizations.
123/// For example, this can result in fairly fragile code as the string paths will need to be
124/// kept in sync with the struct definitions since the order of fields could be easily changed.
125/// Because of this, storing these kinds of paths in persistent storage (i.e. game assets)
126/// is strongly discouraged.
127///
128/// Note that a leading dot (`.`) or hash (`#`) token is implied for the first item in a path,
129/// and may therefore be omitted.
130///
131/// Additionally, an empty path may be used to get the struct itself.
132///
133/// ### Example
134/// ```
135/// # use bevy_reflect::{GetPath, Reflect};
136/// #[derive(Reflect, PartialEq, Debug)]
137/// struct MyStruct {
138///   value: u32
139/// }
140///
141/// let my_struct = MyStruct { value: 123 };
142/// // Access via field name
143/// assert_eq!(my_struct.path::<u32>(".value").unwrap(), &123);
144/// // Access via field index
145/// assert_eq!(my_struct.path::<u32>("#0").unwrap(), &123);
146/// // Access self
147/// assert_eq!(*my_struct.path::<MyStruct>("").unwrap(), my_struct);
148/// ```
149///
150/// ## Tuples and Tuple Structs
151///
152/// [`Tuple`] and [`TupleStruct`] elements also follow a conventional Rust syntax.
153/// Fields are accessed with a dot and the field index: `.0`.
154///
155/// Note that a leading dot (`.`) token is implied for the first item in a path,
156/// and may therefore be omitted.
157///
158/// ### Example
159/// ```
160/// # use bevy_reflect::{GetPath, Reflect};
161/// #[derive(Reflect)]
162/// struct MyTupleStruct(u32);
163///
164/// let my_tuple_struct = MyTupleStruct(123);
165/// assert_eq!(my_tuple_struct.path::<u32>(".0").unwrap(), &123);
166/// ```
167///
168/// ## Lists and Arrays
169///
170/// [`List`] and [`Array`] elements are accessed with brackets: `[0]`.
171///
172/// ### Example
173/// ```
174/// # use bevy_reflect::{GetPath};
175/// let my_list: Vec<u32> = vec![1, 2, 3];
176/// assert_eq!(my_list.path::<u32>("[2]").unwrap(), &3);
177/// ```
178///
179/// ## Enums
180///
181/// Pathing for [`Enum`] elements works a bit differently than in normal Rust.
182/// Usually, you would need to pattern match an enum, branching off on the desired variants.
183/// Paths used by this trait do not have any pattern matching capabilities;
184/// instead, they assume the variant is already known ahead of time.
185///
186/// The syntax used, therefore, depends on the variant being accessed:
187/// - Struct variants use the struct syntax (outlined above)
188/// - Tuple variants use the tuple syntax (outlined above)
189/// - Unit variants have no fields to access
190///
191/// If the variant cannot be known ahead of time, the path will need to be split up
192/// and proper enum pattern matching will need to be handled manually.
193///
194/// ### Example
195/// ```
196/// # use bevy_reflect::{GetPath, Reflect};
197/// #[derive(Reflect)]
198/// enum MyEnum {
199///   Unit,
200///   Tuple(bool),
201///   Struct {
202///     value: u32
203///   }
204/// }
205///
206/// let tuple_variant = MyEnum::Tuple(true);
207/// assert_eq!(tuple_variant.path::<bool>(".0").unwrap(), &true);
208///
209/// let struct_variant = MyEnum::Struct { value: 123 };
210/// // Access via field name
211/// assert_eq!(struct_variant.path::<u32>(".value").unwrap(), &123);
212/// // Access via field index
213/// assert_eq!(struct_variant.path::<u32>("#0").unwrap(), &123);
214///
215/// // Error: Expected struct variant
216/// assert!(matches!(tuple_variant.path::<u32>(".value"), Err(_)));
217/// ```
218///
219/// # Chaining
220///
221/// Using the aforementioned syntax, path items may be chained one after another
222/// to create a full path to a nested element.
223///
224/// ## Example
225/// ```
226/// # use bevy_reflect::{GetPath, Reflect};
227/// #[derive(Reflect)]
228/// struct MyStruct {
229///   value: Vec<Option<u32>>
230/// }
231///
232/// let my_struct = MyStruct {
233///   value: vec![None, None, Some(123)],
234/// };
235/// assert_eq!(
236///   my_struct.path::<u32>(".value[2].0").unwrap(),
237///   &123,
238/// );
239/// ```
240///
241/// [`Struct`]: crate::Struct
242/// [`Tuple`]: crate::Tuple
243/// [`TupleStruct`]: crate::TupleStruct
244/// [`List`]: crate::List
245/// [`Array`]: crate::Array
246/// [`Enum`]: crate::Enum
247#[diagnostic::on_unimplemented(
248    message = "`{Self}` does not implement `GetPath` so cannot be accessed by reflection path",
249    note = "consider annotating `{Self}` with `#[derive(Reflect)]`"
250)]
251pub trait GetPath: PartialReflect {
252    /// Returns a reference to the value specified by `path`.
253    ///
254    /// To retrieve a statically typed reference, use
255    /// [`path`][GetPath::path].
256    fn reflect_path<'p>(&self, path: impl ReflectPath<'p>) -> PathResult<'p, &dyn PartialReflect> {
257        path.reflect_element(self.as_partial_reflect())
258    }
259
260    /// Returns a mutable reference to the value specified by `path`.
261    ///
262    /// To retrieve a statically typed mutable reference, use
263    /// [`path_mut`][GetPath::path_mut].
264    fn reflect_path_mut<'p>(
265        &mut self,
266        path: impl ReflectPath<'p>,
267    ) -> PathResult<'p, &mut dyn PartialReflect> {
268        path.reflect_element_mut(self.as_partial_reflect_mut())
269    }
270
271    /// Returns a statically typed reference to the value specified by `path`.
272    ///
273    /// This will automatically handle downcasting to type `T`.
274    /// The downcast will fail if this value is not of type `T`
275    /// (which may be the case when using dynamic types like [`DynamicStruct`]).
276    ///
277    /// [`DynamicStruct`]: crate::DynamicStruct
278    fn path<'p, T: Reflect>(&self, path: impl ReflectPath<'p>) -> PathResult<'p, &T> {
279        path.element(self.as_partial_reflect())
280    }
281
282    /// Returns a statically typed mutable reference to the value specified by `path`.
283    ///
284    /// This will automatically handle downcasting to type `T`.
285    /// The downcast will fail if this value is not of type `T`
286    /// (which may be the case when using dynamic types like [`DynamicStruct`]).
287    ///
288    /// [`DynamicStruct`]: crate::DynamicStruct
289    fn path_mut<'p, T: Reflect>(&mut self, path: impl ReflectPath<'p>) -> PathResult<'p, &mut T> {
290        path.element_mut(self.as_partial_reflect_mut())
291    }
292}
293
294// Implement `GetPath` for `dyn Reflect`
295impl<T: Reflect + ?Sized> GetPath for T {}
296
297/// An [`Access`] combined with an `offset` for more helpful error reporting.
298#[derive(Clone, Debug, PartialEq, PartialOrd, Ord, Eq, Hash)]
299pub struct OffsetAccess {
300    /// The [`Access`] itself.
301    pub access: Access<'static>,
302    /// A character offset in the string the path was parsed from.
303    pub offset: Option<usize>,
304}
305
306impl From<Access<'static>> for OffsetAccess {
307    fn from(access: Access<'static>) -> Self {
308        OffsetAccess {
309            access,
310            offset: None,
311        }
312    }
313}
314
315/// A pre-parsed path to an element within a type.
316///
317/// This struct can be constructed manually from its [`Access`]es or with
318/// the [parse](ParsedPath::parse) method.
319///
320/// This struct may be used like [`GetPath`] but removes the cost of parsing the path
321/// string at each element access.
322///
323/// It's recommended to use this in place of [`GetPath`] when the path string is
324/// unlikely to be changed and will be accessed repeatedly.
325///
326/// ## Examples
327///
328/// Parsing a [`&'static str`](str):
329/// ```
330/// # use bevy_reflect::ParsedPath;
331/// let my_static_string: &'static str = "bar#0.1[2].0";
332/// // Breakdown:
333/// //   "bar" - Access struct field named "bar"
334/// //   "#0" - Access struct field at index 0
335/// //   ".1" - Access tuple struct field at index 1
336/// //   "[2]" - Access list element at index 2
337/// //   ".0" - Access tuple variant field at index 0
338/// let my_path = ParsedPath::parse_static(my_static_string);
339/// ```
340/// Parsing a non-static [`&str`](str):
341/// ```
342/// # use bevy_reflect::ParsedPath;
343/// let my_string = String::from("bar#0.1[2].0");
344/// // Breakdown:
345/// //   "bar" - Access struct field named "bar"
346/// //   "#0" - Access struct field at index 0
347/// //   ".1" - Access tuple struct field at index 1
348/// //   "[2]" - Access list element at index 2
349/// //   ".0" - Access tuple variant field at index 0
350/// let my_path = ParsedPath::parse(&my_string);
351/// ```
352/// Manually constructing a [`ParsedPath`]:
353/// ```
354/// # use std::borrow::Cow;
355/// # use bevy_reflect::access::Access;
356/// # use bevy_reflect::ParsedPath;
357/// let path_elements = [
358///     Access::Field(Cow::Borrowed("bar")),
359///     Access::FieldIndex(0),
360///     Access::TupleIndex(1),
361///     Access::ListIndex(2),
362///     Access::TupleIndex(1),
363/// ];
364/// let my_path = ParsedPath::from(path_elements);
365/// ```
366#[derive(Clone, Debug, PartialEq, PartialOrd, Ord, Eq, Hash, From)]
367pub struct ParsedPath(
368    /// This is a vector of pre-parsed [`OffsetAccess`]es.
369    pub Vec<OffsetAccess>,
370);
371
372impl ParsedPath {
373    /// Parses a [`ParsedPath`] from a string.
374    ///
375    /// Returns an error if the string does not represent a valid path to an element.
376    ///
377    /// The exact format for path strings can be found in the documentation for [`GetPath`].
378    /// In short, though, a path consists of one or more chained accessor strings.
379    /// These are:
380    /// - Named field access (`.field`)
381    /// - Unnamed field access (`.1`)
382    /// - Field index access (`#0`)
383    /// - Sequence access (`[2]`)
384    ///
385    /// # Example
386    /// ```
387    /// # use bevy_reflect::{ParsedPath, Reflect, ReflectPath};
388    /// #[derive(Reflect)]
389    /// struct Foo {
390    ///   bar: Bar,
391    /// }
392    ///
393    /// #[derive(Reflect)]
394    /// struct Bar {
395    ///   baz: Baz,
396    /// }
397    ///
398    /// #[derive(Reflect)]
399    /// struct Baz(f32, Vec<Option<u32>>);
400    ///
401    /// let foo = Foo {
402    ///   bar: Bar {
403    ///     baz: Baz(3.14, vec![None, None, Some(123)])
404    ///   },
405    /// };
406    ///
407    /// let parsed_path = ParsedPath::parse("bar#0.1[2].0").unwrap();
408    /// // Breakdown:
409    /// //   "bar" - Access struct field named "bar"
410    /// //   "#0" - Access struct field at index 0
411    /// //   ".1" - Access tuple struct field at index 1
412    /// //   "[2]" - Access list element at index 2
413    /// //   ".0" - Access tuple variant field at index 0
414    ///
415    /// assert_eq!(parsed_path.element::<u32>(&foo).unwrap(), &123);
416    /// ```
417    pub fn parse(string: &str) -> PathResult<'_, Self> {
418        let mut parts = Vec::new();
419        for (access, offset) in PathParser::new(string) {
420            parts.push(OffsetAccess {
421                access: access?.into_owned(),
422                offset: Some(offset),
423            });
424        }
425        Ok(Self(parts))
426    }
427
428    /// Similar to [`Self::parse`] but only works on `&'static str`
429    /// and does not allocate per named field.
430    pub fn parse_static(string: &'static str) -> PathResult<'static, Self> {
431        let mut parts = Vec::new();
432        for (access, offset) in PathParser::new(string) {
433            parts.push(OffsetAccess {
434                access: access?,
435                offset: Some(offset),
436            });
437        }
438        Ok(Self(parts))
439    }
440}
441
442impl<'a> ReflectPath<'a> for &'a ParsedPath {
443    fn reflect_element(self, mut root: &dyn PartialReflect) -> PathResult<'a, &dyn PartialReflect> {
444        for OffsetAccess { access, offset } in &self.0 {
445            root = access.element(root, *offset)?;
446        }
447        Ok(root)
448    }
449    fn reflect_element_mut(
450        self,
451        mut root: &mut dyn PartialReflect,
452    ) -> PathResult<'a, &mut dyn PartialReflect> {
453        for OffsetAccess { access, offset } in &self.0 {
454            root = access.element_mut(root, *offset)?;
455        }
456        Ok(root)
457    }
458}
459
460impl<const N: usize> From<[OffsetAccess; N]> for ParsedPath {
461    fn from(value: [OffsetAccess; N]) -> Self {
462        ParsedPath(value.to_vec())
463    }
464}
465
466impl From<Vec<Access<'static>>> for ParsedPath {
467    fn from(value: Vec<Access<'static>>) -> Self {
468        ParsedPath(
469            value
470                .into_iter()
471                .map(|access| OffsetAccess {
472                    access,
473                    offset: None,
474                })
475                .collect(),
476        )
477    }
478}
479
480impl<const N: usize> From<[Access<'static>; N]> for ParsedPath {
481    fn from(value: [Access<'static>; N]) -> Self {
482        value.to_vec().into()
483    }
484}
485
486impl<'a> TryFrom<&'a str> for ParsedPath {
487    type Error = ReflectPathError<'a>;
488    fn try_from(value: &'a str) -> Result<Self, Self::Error> {
489        ParsedPath::parse(value)
490    }
491}
492
493impl fmt::Display for ParsedPath {
494    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
495        for OffsetAccess { access, .. } in &self.0 {
496            write!(f, "{access}")?;
497        }
498        Ok(())
499    }
500}
501
502impl core::ops::Index<usize> for ParsedPath {
503    type Output = OffsetAccess;
504    fn index(&self, index: usize) -> &Self::Output {
505        &self.0[index]
506    }
507}
508
509impl core::ops::IndexMut<usize> for ParsedPath {
510    fn index_mut(&mut self, index: usize) -> &mut Self::Output {
511        &mut self.0[index]
512    }
513}
514
515#[cfg(test)]
516#[expect(
517    clippy::approx_constant,
518    reason = "We don't need the exact value of Pi here."
519)]
520mod tests {
521    use super::*;
522    use crate::*;
523    use alloc::vec;
524
525    #[derive(Reflect, PartialEq, Debug)]
526    struct A {
527        w: usize,
528        x: B,
529        y: Vec<C>,
530        z: D,
531        unit_variant: F,
532        tuple_variant: F,
533        struct_variant: F,
534        array: [i32; 3],
535        tuple: (bool, f32),
536    }
537
538    #[derive(Reflect, PartialEq, Debug)]
539    struct B {
540        foo: usize,
541        łørđ: C,
542    }
543
544    #[derive(Reflect, PartialEq, Debug)]
545    struct C {
546        mосква: f32,
547    }
548
549    #[derive(Reflect, PartialEq, Debug)]
550    struct D(E);
551
552    #[derive(Reflect, PartialEq, Debug)]
553    struct E(f32, usize);
554
555    #[derive(Reflect, PartialEq, Debug)]
556    enum F {
557        Unit,
558        Tuple(u32, u32),
559        Şķràźÿ { 東京: char },
560    }
561
562    fn a_sample() -> A {
563        A {
564            w: 1,
565            x: B {
566                foo: 10,
567                łørđ: C { mосква: 3.14 },
568            },
569            y: vec![C { mосква: 1.0 }, C { mосква: 2.0 }],
570            z: D(E(10.0, 42)),
571            unit_variant: F::Unit,
572            tuple_variant: F::Tuple(123, 321),
573            struct_variant: F::Şķràźÿ { 東京: 'm' },
574            array: [86, 75, 309],
575            tuple: (true, 1.23),
576        }
577    }
578
579    fn offset(access: Access<'static>, offset: usize) -> OffsetAccess {
580        OffsetAccess {
581            access,
582            offset: Some(offset),
583        }
584    }
585
586    fn access_field(field: &'static str) -> Access<'static> {
587        Access::Field(field.into())
588    }
589
590    type StaticError = ReflectPathError<'static>;
591
592    fn invalid_access(
593        offset: usize,
594        actual: ReflectKind,
595        expected: ReflectKind,
596        access: &'static str,
597    ) -> StaticError {
598        ReflectPathError::InvalidAccess(AccessError {
599            kind: AccessErrorKind::IncompatibleTypes { actual, expected },
600            access: ParsedPath::parse_static(access).unwrap()[1].access.clone(),
601            offset: Some(offset),
602        })
603    }
604
605    #[test]
606    fn try_from() {
607        assert_eq!(
608            ParsedPath::try_from("w").unwrap().0,
609            &[offset(access_field("w"), 1)]
610        );
611
612        let r = ParsedPath::try_from("w[");
613        let matches = matches!(r, Err(ReflectPathError::ParseError { .. }));
614        assert!(
615            matches,
616            "ParsedPath::try_from did not return a ParseError for \"w[\""
617        );
618    }
619
620    #[test]
621    fn parsed_path_parse() {
622        assert_eq!(
623            ParsedPath::parse("w").unwrap().0,
624            &[offset(access_field("w"), 1)]
625        );
626        assert_eq!(
627            ParsedPath::parse("x.foo").unwrap().0,
628            &[offset(access_field("x"), 1), offset(access_field("foo"), 2)]
629        );
630        assert_eq!(
631            ParsedPath::parse("x.łørđ.mосква").unwrap().0,
632            &[
633                offset(access_field("x"), 1),
634                offset(access_field("łørđ"), 2),
635                offset(access_field("mосква"), 10)
636            ]
637        );
638        assert_eq!(
639            ParsedPath::parse("y[1].mосква").unwrap().0,
640            &[
641                offset(access_field("y"), 1),
642                offset(Access::ListIndex(1), 2),
643                offset(access_field("mосква"), 5)
644            ]
645        );
646        assert_eq!(
647            ParsedPath::parse("z.0.1").unwrap().0,
648            &[
649                offset(access_field("z"), 1),
650                offset(Access::TupleIndex(0), 2),
651                offset(Access::TupleIndex(1), 4),
652            ]
653        );
654        assert_eq!(
655            ParsedPath::parse("x#0").unwrap().0,
656            &[
657                offset(access_field("x"), 1),
658                offset(Access::FieldIndex(0), 2)
659            ]
660        );
661        assert_eq!(
662            ParsedPath::parse("x#0#1").unwrap().0,
663            &[
664                offset(access_field("x"), 1),
665                offset(Access::FieldIndex(0), 2),
666                offset(Access::FieldIndex(1), 4)
667            ]
668        );
669    }
670
671    #[test]
672    fn parsed_path_get_field() {
673        let a = a_sample();
674
675        let b = ParsedPath::parse("w").unwrap();
676        let c = ParsedPath::parse("x.foo").unwrap();
677        let d = ParsedPath::parse("x.łørđ.mосква").unwrap();
678        let e = ParsedPath::parse("y[1].mосква").unwrap();
679        let f = ParsedPath::parse("z.0.1").unwrap();
680        let g = ParsedPath::parse("x#0").unwrap();
681        let h = ParsedPath::parse("x#1#0").unwrap();
682        let i = ParsedPath::parse("unit_variant").unwrap();
683        let j = ParsedPath::parse("tuple_variant.1").unwrap();
684        let k = ParsedPath::parse("struct_variant.東京").unwrap();
685        let l = ParsedPath::parse("struct_variant#0").unwrap();
686        let m = ParsedPath::parse("array[2]").unwrap();
687        let n = ParsedPath::parse("tuple.1").unwrap();
688
689        for _ in 0..30 {
690            assert_eq!(*b.element::<usize>(&a).unwrap(), 1);
691            assert_eq!(*c.element::<usize>(&a).unwrap(), 10);
692            assert_eq!(*d.element::<f32>(&a).unwrap(), 3.14);
693            assert_eq!(*e.element::<f32>(&a).unwrap(), 2.0);
694            assert_eq!(*f.element::<usize>(&a).unwrap(), 42);
695            assert_eq!(*g.element::<usize>(&a).unwrap(), 10);
696            assert_eq!(*h.element::<f32>(&a).unwrap(), 3.14);
697            assert_eq!(*i.element::<F>(&a).unwrap(), F::Unit);
698            assert_eq!(*j.element::<u32>(&a).unwrap(), 321);
699            assert_eq!(*k.element::<char>(&a).unwrap(), 'm');
700            assert_eq!(*l.element::<char>(&a).unwrap(), 'm');
701            assert_eq!(*m.element::<i32>(&a).unwrap(), 309);
702            assert_eq!(*n.element::<f32>(&a).unwrap(), 1.23);
703        }
704    }
705
706    #[test]
707    fn reflect_array_behaves_like_list() {
708        #[derive(Reflect)]
709        struct A {
710            list: Vec<u8>,
711            array: [u8; 10],
712        }
713
714        let a = A {
715            list: vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
716            array: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
717        };
718
719        assert_eq!(*a.path::<u8>("list[5]").unwrap(), 5);
720        assert_eq!(*a.path::<u8>("array[5]").unwrap(), 5);
721        assert_eq!(*a.path::<u8>("list[0]").unwrap(), 0);
722        assert_eq!(*a.path::<u8>("array[0]").unwrap(), 0);
723    }
724
725    #[test]
726    fn reflect_array_behaves_like_list_mut() {
727        #[derive(Reflect)]
728        struct A {
729            list: Vec<u8>,
730            array: [u8; 10],
731        }
732
733        let mut a = A {
734            list: vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
735            array: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
736        };
737
738        assert_eq!(*a.path_mut::<u8>("list[5]").unwrap(), 5);
739        assert_eq!(*a.path_mut::<u8>("array[5]").unwrap(), 5);
740
741        *a.path_mut::<u8>("list[5]").unwrap() = 10;
742        *a.path_mut::<u8>("array[5]").unwrap() = 10;
743
744        assert_eq!(*a.path_mut::<u8>("list[5]").unwrap(), 10);
745        assert_eq!(*a.path_mut::<u8>("array[5]").unwrap(), 10);
746    }
747
748    #[test]
749    fn reflect_path() {
750        let mut a = a_sample();
751
752        assert_eq!(*a.path::<A>("").unwrap(), a);
753        assert_eq!(*a.path::<usize>("w").unwrap(), 1);
754        assert_eq!(*a.path::<usize>("x.foo").unwrap(), 10);
755        assert_eq!(*a.path::<f32>("x.łørđ.mосква").unwrap(), 3.14);
756        assert_eq!(*a.path::<f32>("y[1].mосква").unwrap(), 2.0);
757        assert_eq!(*a.path::<usize>("z.0.1").unwrap(), 42);
758        assert_eq!(*a.path::<usize>("x#0").unwrap(), 10);
759        assert_eq!(*a.path::<f32>("x#1#0").unwrap(), 3.14);
760
761        assert_eq!(*a.path::<F>("unit_variant").unwrap(), F::Unit);
762        assert_eq!(*a.path::<u32>("tuple_variant.1").unwrap(), 321);
763        assert_eq!(*a.path::<char>("struct_variant.東京").unwrap(), 'm');
764        assert_eq!(*a.path::<char>("struct_variant#0").unwrap(), 'm');
765
766        assert_eq!(*a.path::<i32>("array[2]").unwrap(), 309);
767
768        assert_eq!(*a.path::<f32>("tuple.1").unwrap(), 1.23);
769        *a.path_mut::<f32>("tuple.1").unwrap() = 3.21;
770        assert_eq!(*a.path::<f32>("tuple.1").unwrap(), 3.21);
771
772        *a.path_mut::<f32>("y[1].mосква").unwrap() = 3.0;
773        assert_eq!(a.y[1].mосква, 3.0);
774
775        *a.path_mut::<u32>("tuple_variant.0").unwrap() = 1337;
776        assert_eq!(a.tuple_variant, F::Tuple(1337, 321));
777
778        assert_eq!(
779            a.reflect_path("x.notreal").err().unwrap(),
780            ReflectPathError::InvalidAccess(AccessError {
781                kind: AccessErrorKind::MissingField(ReflectKind::Struct),
782                access: access_field("notreal"),
783                offset: Some(2),
784            })
785        );
786
787        assert_eq!(
788            a.reflect_path("unit_variant.0").err().unwrap(),
789            ReflectPathError::InvalidAccess(AccessError {
790                kind: AccessErrorKind::IncompatibleEnumVariantTypes {
791                    actual: VariantType::Unit,
792                    expected: VariantType::Tuple,
793                },
794                access: ParsedPath::parse_static("unit_variant.0").unwrap()[1]
795                    .access
796                    .clone(),
797                offset: Some(13),
798            })
799        );
800        assert_eq!(
801            a.reflect_path("x[0]").err().unwrap(),
802            invalid_access(2, ReflectKind::Struct, ReflectKind::List, "x[0]")
803        );
804        assert_eq!(
805            a.reflect_path("y.x").err().unwrap(),
806            invalid_access(2, ReflectKind::List, ReflectKind::Struct, "y.x")
807        );
808    }
809
810    #[test]
811    fn accept_leading_tokens() {
812        assert_eq!(
813            ParsedPath::parse(".w").unwrap().0,
814            &[offset(access_field("w"), 1)]
815        );
816        assert_eq!(
817            ParsedPath::parse("#0.foo").unwrap().0,
818            &[
819                offset(Access::FieldIndex(0), 1),
820                offset(access_field("foo"), 3)
821            ]
822        );
823        assert_eq!(
824            ParsedPath::parse(".5").unwrap().0,
825            &[offset(Access::TupleIndex(5), 1)]
826        );
827        assert_eq!(
828            ParsedPath::parse("[0].łørđ").unwrap().0,
829            &[
830                offset(Access::ListIndex(0), 1),
831                offset(access_field("łørđ"), 4)
832            ]
833        );
834    }
835}
bevy_reflect/path/mod.rs

bevy_reflect/path/
mod.rs
