treaty -


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use crate::{
    build::{Build, Builder},
    walk::{Walk, WalkMut, WalkOnce},
};

#[derive(thiserror::Error, Debug)]
pub enum Either<A, B> {
    #[error(transparent)]
    A(A),

    #[error(transparent)]
    B(B),
}

pub fn from<'ctx, U, T>(
    value: T,
) -> Result<U, Either<T::Error, <U::Builder as Builder<'ctx>>::Error>>
where
    T: WalkOnce<'ctx>,
    U: Build<'ctx>,
{
    let mut builder = U::Builder::default();
    value.walk_once(builder.as_visitor()).map_err(Either::A)?;
    builder.build().map_err(Either::B)
}

pub fn from_mut<'a, 'ctx, U, T>(
    value: &'a mut T,
) -> Result<U, Either<T::Error, <U::Builder as Builder<'ctx>>::Error>>
where
    T: WalkMut<'a, 'ctx>,
    U: Build<'ctx>,
{
    let mut builder = U::Builder::default();
    value.walk_mut(builder.as_visitor()).map_err(Either::A)?;
    builder.build().map_err(Either::B)
}

pub fn from_ref<'a, 'ctx, U, T>(
    value: &'a T,
) -> Result<U, Either<T::Error, <U::Builder as Builder<'ctx>>::Error>>
where
    T: Walk<'a, 'ctx>,
    U: Build<'ctx>,
{
    let mut builder = U::Builder::default();
    value.walk(builder.as_visitor()).map_err(Either::A)?;
    builder.build().map_err(Either::B)
}