bevy/crates/bevy_reflect/src/enums/helpers.rs
Carter Anderson e5905379de Use new let-else syntax where possible (#6463)
# Objective

Let-else syntax is now stable!

## Solution

Use it where possible!
2022-11-04 21:32:09 +00:00

119 lines
3.6 KiB
Rust

use crate::{Enum, Reflect, ReflectRef, VariantType};
use std::fmt::Debug;
use std::hash::{Hash, Hasher};
/// Returns the `u64` hash of the given [enum](Enum).
#[inline]
pub fn enum_hash<TEnum: Enum>(value: &TEnum) -> Option<u64> {
let mut hasher = crate::ReflectHasher::default();
std::any::Any::type_id(value).hash(&mut hasher);
value.variant_name().hash(&mut hasher);
value.variant_type().hash(&mut hasher);
for field in value.iter_fields() {
hasher.write_u64(field.value().reflect_hash()?);
}
Some(hasher.finish())
}
/// Compares an [`Enum`] with a [`Reflect`] value.
///
/// Returns true if and only if all of the following are true:
/// - `b` is an enum;
/// - `b` is the same variant as `a`;
/// - For each field in `a`, `b` contains a field with the same name and
/// [`Reflect::reflect_partial_eq`] returns `Some(true)` for the two field
/// values.
#[inline]
pub fn enum_partial_eq<TEnum: Enum>(a: &TEnum, b: &dyn Reflect) -> Option<bool> {
// Both enums?
let ReflectRef::Enum(b) = b.reflect_ref() else {
return Some(false);
};
// Same variant name?
if a.variant_name() != b.variant_name() {
return Some(false);
}
// Same variant type?
if !a.is_variant(b.variant_type()) {
return Some(false);
}
match a.variant_type() {
VariantType::Struct => {
// Same struct fields?
for field in a.iter_fields() {
let field_name = field.name().unwrap();
if let Some(field_value) = b.field(field_name) {
if let Some(false) | None = field_value.reflect_partial_eq(field.value()) {
// Fields failed comparison
return Some(false);
}
} else {
// Field does not exist
return Some(false);
}
}
Some(true)
}
VariantType::Tuple => {
// Same tuple fields?
for (i, field) in a.iter_fields().enumerate() {
if let Some(field_value) = b.field_at(i) {
if let Some(false) | None = field_value.reflect_partial_eq(field.value()) {
// Fields failed comparison
return Some(false);
}
} else {
// Field does not exist
return Some(false);
}
}
Some(true)
}
_ => Some(true),
}
}
/// The default debug formatter for [`Enum`] types.
///
/// # Example
/// ```
/// use bevy_reflect::Reflect;
/// #[derive(Reflect)]
/// enum MyEnum {
/// A,
/// B (usize),
/// C {value: i32}
/// }
///
/// let my_enum: &dyn Reflect = &MyEnum::B(123);
/// println!("{:#?}", my_enum);
///
/// // Output:
///
/// // B (
/// // 123,
/// // )
/// ```
#[inline]
pub fn enum_debug(dyn_enum: &dyn Enum, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match dyn_enum.variant_type() {
VariantType::Unit => f.write_str(dyn_enum.variant_name()),
VariantType::Tuple => {
let mut debug = f.debug_tuple(dyn_enum.variant_name());
for field in dyn_enum.iter_fields() {
debug.field(&field.value() as &dyn Debug);
}
debug.finish()
}
VariantType::Struct => {
let mut debug = f.debug_struct(dyn_enum.variant_name());
for field in dyn_enum.iter_fields() {
debug.field(field.name().unwrap(), &field.value() as &dyn Debug);
}
debug.finish()
}
}
}