bevy_mod_config 0.7.1

use crate::ConfigField;

/// Implemented by the discriminant type generated by [`crate::Config`] when derived for enums.
///
/// [Managers](crate::Manager) that support enum config fields should blanket-implement
/// [`manager::Supports<T>`](crate::manager::Supports) for all `T: EnumDiscriminant`.
pub trait EnumDiscriminant: ConfigField + Eq + Sized + Copy + Send + Sync + 'static {
    /// Lists all variants of the enum.
    const VARIANTS: &'static [Self];

    /// Returns the index of the variant in [`VARIANTS`](Self::VARIANTS).
    fn into_usize(self) -> usize;

    /// Returns the enum variant name.
    fn name(self) -> &'static str;

    /// Returns the enum variant with the given name if any.
    fn from_name(name: &str) -> Option<Self>;
}

/// A [`ConfigField`] implementation that wraps an [`EnumDiscriminant`] implementor.
#[derive(PartialEq)]
pub struct EnumDiscriminantWrapper<T>(pub T);

/// [Metadata](ConfigField::Metadata) type for enum discriminants.
///
/// `T` is the discrim type derived in `#[derive(Config)]` for the corresponding enum.
/// Use `#[config(expose(discrim))]` and reference it as `{StructName}Discrim`.
#[derive(Default, Clone)]
pub struct EnumDiscriminantMetadata<T> {
    /// The default enum variant.
    pub default: T,
}

/// [Metadata](ConfigField::Metadata) type for fields whose type is a [`Config`](crate::Config)-derived enum.
///
/// Used as the `Metadata` associated type when a `#[derive(Config)]` enum
/// is referenced as a field in another `#[derive(Config)]` struct or enum.
/// This allows per-field overrides of the default discriminant.
#[derive(Clone)]
pub struct EnumFieldMetadata<Discrim: ConfigField> {
    /// Metadata for the enum discriminant.
    /// The value has type [`EnumDiscriminantMetadata`] for the corresponding enum.
    ///
    /// # Example
    /// ```
    /// # use bevy_mod_config::Config;
    /// #
    /// #[derive(Config)]
    /// #[config(expose(discrim))]
    /// enum Fruit {
    ///     Apple,
    ///     Orange,
    /// }
    ///
    /// #[derive(Config)]
    /// struct Menu {
    ///     lunch:  Fruit,
    ///     #[config(discrim.default = FruitDiscrim::Orange)]
    ///     dinner: Fruit,
    /// }
    /// ```
    pub discrim: Discrim::Metadata,
}

impl<Discrim: ConfigField> Default for EnumFieldMetadata<Discrim>
where
    Discrim::Metadata: Default,
{
    fn default() -> Self { Self { discrim: Discrim::Metadata::default() } }
}