statime-config 0.1.0

use crate::{
    Merge, PartialValue,
    tree::{EffectivelyUnset, setting::Setting},
};

/// Relates a configuration type to how it is represented while a configuration
/// is still being loaded.
///
/// This is what lets every field of a partial struct be written the same way,
/// as `<FieldType as Configurable>::Node`, without knowing whether the field
/// holds an atomic value or a nested struct: the type itself answers that.
pub trait Configurable {
    /// How this type is represented before defaults are applied.
    type Partial: PartialValue<Resolved = Self>;

    /// How a field of this type is stored in the partial struct holding it.
    /// Atomic values are stored in a [`Setting`], nested structs in a
    /// [`Section`](crate::tree::section::Section).
    type Node: PartialValue
        + Default
        + EffectivelyUnset
        + Merge
        + serde::Serialize
        + for<'a> serde::Deserialize<'a>;
}

/// A vector is atomic for merging, so it is stored in a single setting, while
/// its elements stay partial so that they can be defaulted individually.
impl<T> Configurable for Vec<T>
where
    T: Configurable,
    <T as Configurable>::Partial: serde::Serialize + for<'a> serde::Deserialize<'a>,
{
    type Partial = Vec<T::Partial>;
    type Node = Setting<Vec<T::Partial>>;
}