treaty -


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use crate::{UniError, Visitor, WalkStatus, Walker};

/// A type buildable from a walker.
pub trait Build<'value, 'ctx: 'value, WalkerErr>: Sized {
    type Error;

    /// The builder that can be used to build a value.
    type Builder: Builder<'value, 'ctx, WalkerErr, Value = Self, Error = Self::Error>;
}

// /// Build a [`Buildable`] type from a walker.
// ///
// /// This calls [`Walker::walk`] on the walker.
// pub fn build<
//     'value,
//     'ctx: 'value,
//     T: Build<'value, 'ctx, W::Error, Error = VisitorErr>,
//     VisitorErr,
//     W: ?Sized + Walker<'value, 'ctx, VisitorErr>,
// >(
//     walker: &mut W,
// ) -> Result<(T, WalkStatus), UniError<W::Error, VisitorErr>> {
//     T::Builder::build(walker)
// }
//
// pub trait BuilderExt<'value, 'ctx: 'value, WalkerErr>: Builder<'value, 'ctx, WalkerErr> {
//     fn build<W: ?Sized + Walker<'value, 'ctx, Self::Error, Error = WalkerErr>>(
//         walker: &mut W,
//     ) -> Result<(Self::Value, WalkStatus), UniError<WalkerErr, Self::Error>>;
// }
//
// impl<'value, 'ctx: 'value, WalkerErr, T: Builder<'value, 'ctx, WalkerErr>> BuilderExt<'value, 'ctx, WalkerErr> for T {
//     fn build<W: ?Sized + Walker<'value, 'ctx, Self::Error, Error = WalkerErr>>(
//         walker: &mut W,
//     ) -> Result<(Self::Value, WalkStatus), UniError<WalkerErr, Self::Error>> {
//         let mut builder = Self::init();
//         let status = walker.walk(builder.as_visitor())?;
//         Ok((builder.finish()?, status))
//     }
// }

/// Extension to [`Visitor`] that allows constructing and finishing the visitor.
pub trait Builder<'value, 'ctx: 'value, WalkerErr> {
    type Error;

    /// Type to be built.
    type Value: Sized;

    /// Init a new builder.
    fn init() -> Self
    where
        Self: Sized;

    /// As a visitor.
    fn as_visitor(&mut self) -> &mut dyn Visitor<'value, 'ctx, WalkerErr, Error = Self::Error>;

    /// Finish the value.
    fn finish(self) -> Result<Self::Value, UniError<WalkerErr, Self::Error>>
    where
        Self: Sized;
}