bevy_reflect/array.rs
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use crate::{
self as bevy_reflect, utility::reflect_hasher, ApplyError, Reflect, ReflectKind, ReflectMut,
ReflectOwned, ReflectRef, TypeInfo, TypePath, TypePathTable,
};
use bevy_reflect_derive::impl_type_path;
use std::{
any::{Any, TypeId},
fmt::{Debug, Formatter},
hash::{Hash, Hasher},
};
/// A trait used to power [array-like] operations via [reflection].
///
/// This corresponds to true Rust arrays like `[T; N]`,
/// but also to any fixed-size linear sequence types.
/// It is expected that implementors of this trait uphold this contract
/// and maintain a fixed size as returned by the [`Array::len`] method.
///
/// Due to the [type-erasing] nature of the reflection API as a whole,
/// this trait does not make any guarantees that the implementor's elements
/// are homogeneous (i.e. all the same type).
///
/// This trait has a blanket implementation over Rust arrays of up to 32 items.
/// This implementation can technically contain more than 32,
/// but the blanket [`GetTypeRegistration`] is only implemented up to the 32
/// item limit due to a [limitation] on [`Deserialize`].
///
/// # Example
///
/// ```
/// use bevy_reflect::{Reflect, Array};
///
/// let foo: &dyn Array = &[123_u32, 456_u32, 789_u32];
/// assert_eq!(foo.len(), 3);
///
/// let field: &dyn Reflect = foo.get(0).unwrap();
/// assert_eq!(field.downcast_ref::<u32>(), Some(&123));
/// ```
///
/// [array-like]: https://doc.rust-lang.org/book/ch03-02-data-types.html#the-array-type
/// [reflection]: crate
/// [`List`]: crate::List
/// [type-erasing]: https://doc.rust-lang.org/book/ch17-02-trait-objects.html
/// [`GetTypeRegistration`]: crate::GetTypeRegistration
/// [limitation]: https://github.com/serde-rs/serde/issues/1937
/// [`Deserialize`]: ::serde::Deserialize
pub trait Array: Reflect {
/// Returns a reference to the element at `index`, or `None` if out of bounds.
fn get(&self, index: usize) -> Option<&dyn Reflect>;
/// Returns a mutable reference to the element at `index`, or `None` if out of bounds.
fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect>;
/// Returns the number of elements in the array.
fn len(&self) -> usize;
/// Returns `true` if the collection contains no elements.
fn is_empty(&self) -> bool {
self.len() == 0
}
/// Returns an iterator over the array.
fn iter(&self) -> ArrayIter;
/// Drain the elements of this array to get a vector of owned values.
fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>>;
/// Clones the list, producing a [`DynamicArray`].
fn clone_dynamic(&self) -> DynamicArray {
DynamicArray {
represented_type: self.get_represented_type_info(),
values: self.iter().map(|value| value.clone_value()).collect(),
}
}
}
/// A container for compile-time array info.
#[derive(Clone, Debug)]
pub struct ArrayInfo {
type_path: TypePathTable,
type_id: TypeId,
item_type_path: TypePathTable,
item_type_id: TypeId,
capacity: usize,
#[cfg(feature = "documentation")]
docs: Option<&'static str>,
}
impl ArrayInfo {
/// Create a new [`ArrayInfo`].
///
/// # Arguments
///
/// * `capacity`: The maximum capacity of the underlying array.
///
pub fn new<TArray: Array + TypePath, TItem: Reflect + TypePath>(capacity: usize) -> Self {
Self {
type_path: TypePathTable::of::<TArray>(),
type_id: TypeId::of::<TArray>(),
item_type_path: TypePathTable::of::<TItem>(),
item_type_id: TypeId::of::<TItem>(),
capacity,
#[cfg(feature = "documentation")]
docs: None,
}
}
/// Sets the docstring for this array.
#[cfg(feature = "documentation")]
pub fn with_docs(self, docs: Option<&'static str>) -> Self {
Self { docs, ..self }
}
/// The compile-time capacity of the array.
pub fn capacity(&self) -> usize {
self.capacity
}
/// A representation of the type path of the array.
///
/// Provides dynamic access to all methods on [`TypePath`].
pub fn type_path_table(&self) -> &TypePathTable {
&self.type_path
}
/// The [stable, full type path] of the array.
///
/// Use [`type_path_table`] if you need access to the other methods on [`TypePath`].
///
/// [stable, full type path]: TypePath
/// [`type_path_table`]: Self::type_path_table
pub fn type_path(&self) -> &'static str {
self.type_path_table().path()
}
/// The [`TypeId`] of the array.
pub fn type_id(&self) -> TypeId {
self.type_id
}
/// Check if the given type matches the array type.
pub fn is<T: Any>(&self) -> bool {
TypeId::of::<T>() == self.type_id
}
/// A representation of the type path of the array item.
///
/// Provides dynamic access to all methods on [`TypePath`].
pub fn item_type_path_table(&self) -> &TypePathTable {
&self.item_type_path
}
/// The [`TypeId`] of the array item.
pub fn item_type_id(&self) -> TypeId {
self.item_type_id
}
/// Check if the given type matches the array item type.
pub fn item_is<T: Any>(&self) -> bool {
TypeId::of::<T>() == self.item_type_id
}
/// The docstring of this array, if any.
#[cfg(feature = "documentation")]
pub fn docs(&self) -> Option<&'static str> {
self.docs
}
}
/// A fixed-size list of reflected values.
///
/// This differs from [`DynamicList`] in that the size of the [`DynamicArray`]
/// is constant, whereas a [`DynamicList`] can have items added and removed.
///
/// This isn't to say that a [`DynamicArray`] is immutable— its items
/// can be mutated— just that the _number_ of items cannot change.
///
/// [`DynamicList`]: crate::DynamicList
#[derive(Debug)]
pub struct DynamicArray {
pub(crate) represented_type: Option<&'static TypeInfo>,
pub(crate) values: Box<[Box<dyn Reflect>]>,
}
impl DynamicArray {
#[inline]
pub fn new(values: Box<[Box<dyn Reflect>]>) -> Self {
Self {
represented_type: None,
values,
}
}
pub fn from_vec<T: Reflect>(values: Vec<T>) -> Self {
Self {
represented_type: None,
values: values
.into_iter()
.map(|field| Box::new(field) as Box<dyn Reflect>)
.collect::<Vec<_>>()
.into_boxed_slice(),
}
}
/// Sets the [type] to be represented by this `DynamicArray`.
///
/// # Panics
///
/// Panics if the given [type] is not a [`TypeInfo::Array`].
///
/// [type]: TypeInfo
pub fn set_represented_type(&mut self, represented_type: Option<&'static TypeInfo>) {
if let Some(represented_type) = represented_type {
assert!(
matches!(represented_type, TypeInfo::Array(_)),
"expected TypeInfo::Array but received: {:?}",
represented_type
);
}
self.represented_type = represented_type;
}
}
impl Reflect for DynamicArray {
#[inline]
fn get_represented_type_info(&self) -> Option<&'static TypeInfo> {
self.represented_type
}
#[inline]
fn into_any(self: Box<Self>) -> Box<dyn Any> {
self
}
#[inline]
fn as_any(&self) -> &dyn Any {
self
}
#[inline]
fn as_any_mut(&mut self) -> &mut dyn Any {
self
}
#[inline]
fn into_reflect(self: Box<Self>) -> Box<dyn Reflect> {
self
}
#[inline]
fn as_reflect(&self) -> &dyn Reflect {
self
}
#[inline]
fn as_reflect_mut(&mut self) -> &mut dyn Reflect {
self
}
fn apply(&mut self, value: &dyn Reflect) {
array_apply(self, value);
}
fn try_apply(&mut self, value: &dyn Reflect) -> Result<(), ApplyError> {
array_try_apply(self, value)
}
#[inline]
fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>> {
*self = value.take()?;
Ok(())
}
#[inline]
fn reflect_kind(&self) -> ReflectKind {
ReflectKind::Array
}
#[inline]
fn reflect_ref(&self) -> ReflectRef {
ReflectRef::Array(self)
}
#[inline]
fn reflect_mut(&mut self) -> ReflectMut {
ReflectMut::Array(self)
}
#[inline]
fn reflect_owned(self: Box<Self>) -> ReflectOwned {
ReflectOwned::Array(self)
}
#[inline]
fn clone_value(&self) -> Box<dyn Reflect> {
Box::new(self.clone_dynamic())
}
#[inline]
fn reflect_hash(&self) -> Option<u64> {
array_hash(self)
}
fn reflect_partial_eq(&self, value: &dyn Reflect) -> Option<bool> {
array_partial_eq(self, value)
}
fn debug(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
write!(f, "DynamicArray(")?;
array_debug(self, f)?;
write!(f, ")")
}
#[inline]
fn is_dynamic(&self) -> bool {
true
}
}
impl Array for DynamicArray {
#[inline]
fn get(&self, index: usize) -> Option<&dyn Reflect> {
self.values.get(index).map(|value| &**value)
}
#[inline]
fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {
self.values.get_mut(index).map(|value| &mut **value)
}
#[inline]
fn len(&self) -> usize {
self.values.len()
}
#[inline]
fn iter(&self) -> ArrayIter {
ArrayIter::new(self)
}
#[inline]
fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {
self.values.into_vec()
}
#[inline]
fn clone_dynamic(&self) -> DynamicArray {
DynamicArray {
represented_type: self.represented_type,
values: self
.values
.iter()
.map(|value| value.clone_value())
.collect(),
}
}
}
impl_type_path!((in bevy_reflect) DynamicArray);
/// An iterator over an [`Array`].
pub struct ArrayIter<'a> {
array: &'a dyn Array,
index: usize,
}
impl<'a> ArrayIter<'a> {
/// Creates a new [`ArrayIter`].
#[inline]
pub const fn new(array: &'a dyn Array) -> ArrayIter {
ArrayIter { array, index: 0 }
}
}
impl<'a> Iterator for ArrayIter<'a> {
type Item = &'a dyn Reflect;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
let value = self.array.get(self.index);
self.index += value.is_some() as usize;
value
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let size = self.array.len();
(size, Some(size))
}
}
impl<'a> ExactSizeIterator for ArrayIter<'a> {}
/// Returns the `u64` hash of the given [array](Array).
#[inline]
pub fn array_hash<A: Array>(array: &A) -> Option<u64> {
let mut hasher = reflect_hasher();
Any::type_id(array).hash(&mut hasher);
array.len().hash(&mut hasher);
for value in array.iter() {
hasher.write_u64(value.reflect_hash()?);
}
Some(hasher.finish())
}
/// Applies the reflected [array](Array) data to the given [array](Array).
///
/// # Panics
///
/// * Panics if the two arrays have differing lengths.
/// * Panics if the reflected value is not a [valid array](ReflectRef::Array).
///
#[inline]
pub fn array_apply<A: Array>(array: &mut A, reflect: &dyn Reflect) {
if let ReflectRef::Array(reflect_array) = reflect.reflect_ref() {
if array.len() != reflect_array.len() {
panic!("Attempted to apply different sized `Array` types.");
}
for (i, value) in reflect_array.iter().enumerate() {
let v = array.get_mut(i).unwrap();
v.apply(value);
}
} else {
panic!("Attempted to apply a non-`Array` type to an `Array` type.");
}
}
/// Tries to apply the reflected [array](Array) data to the given [array](Array) and
/// returns a Result.
///
/// # Errors
///
/// * Returns an [`ApplyError::DifferentSize`] if the two arrays have differing lengths.
/// * Returns an [`ApplyError::MismatchedKinds`] if the reflected value is not a
/// [valid array](ReflectRef::Array).
/// * Returns any error that is generated while applying elements to each other.
///
#[inline]
pub fn array_try_apply<A: Array>(array: &mut A, reflect: &dyn Reflect) -> Result<(), ApplyError> {
if let ReflectRef::Array(reflect_array) = reflect.reflect_ref() {
if array.len() != reflect_array.len() {
return Err(ApplyError::DifferentSize {
from_size: reflect_array.len(),
to_size: array.len(),
});
}
for (i, value) in reflect_array.iter().enumerate() {
let v = array.get_mut(i).unwrap();
v.try_apply(value)?;
}
} else {
return Err(ApplyError::MismatchedKinds {
from_kind: reflect.reflect_kind(),
to_kind: ReflectKind::Array,
});
}
Ok(())
}
/// Compares two [arrays](Array) (one concrete and one reflected) to see if they
/// are equal.
///
/// Returns [`None`] if the comparison couldn't even be performed.
#[inline]
pub fn array_partial_eq<A: Array>(array: &A, reflect: &dyn Reflect) -> Option<bool> {
match reflect.reflect_ref() {
ReflectRef::Array(reflect_array) if reflect_array.len() == array.len() => {
for (a, b) in array.iter().zip(reflect_array.iter()) {
let eq_result = a.reflect_partial_eq(b);
if let failed @ (Some(false) | None) = eq_result {
return failed;
}
}
}
_ => return Some(false),
}
Some(true)
}
/// The default debug formatter for [`Array`] types.
///
/// # Example
/// ```
/// use bevy_reflect::Reflect;
///
/// let my_array: &dyn Reflect = &[1, 2, 3];
/// println!("{:#?}", my_array);
///
/// // Output:
///
/// // [
/// // 1,
/// // 2,
/// // 3,
/// // ]
/// ```
#[inline]
pub fn array_debug(dyn_array: &dyn Array, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let mut debug = f.debug_list();
for item in dyn_array.iter() {
debug.entry(&item as &dyn Debug);
}
debug.finish()
}
#[cfg(test)]
mod tests {
use crate::{Reflect, ReflectRef};
#[test]
fn next_index_increment() {
const SIZE: usize = if cfg!(debug_assertions) {
4
} else {
// If compiled in release mode, verify we dont overflow
usize::MAX
};
let b = Box::new([(); SIZE]).into_reflect();
let ReflectRef::Array(array) = b.reflect_ref() else {
panic!("Not an array...");
};
let mut iter = array.iter();
iter.index = SIZE - 1;
assert!(iter.next().is_some());
// When None we should no longer increase index
assert!(iter.next().is_none());
assert!(iter.index == SIZE);
assert!(iter.next().is_none());
assert!(iter.index == SIZE);
}
}