// This file is part of ICU4X. For terms of use, please see the file

// called LICENSE at the top level of the ICU4X source tree

// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).

use crate::trait_hack::YokeTraitHack;

use crate::Yoke;

use crate::Yokeable;

use core::ops::Deref;

use stable_deref_trait::StableDeref;

use crate::ZeroFrom;

impl<'zf, C: ?Sized, T> ZeroFrom<'zf, C> for YokeTraitHack<T>

where

    T: ZeroFrom<'zf, C>,

{

    #[inline]

    fn zero_from(cart: &'zf C) -> Self {

        YokeTraitHack(T::zero_from(cart))

    }

}

impl<Y, C> Yoke<Y, C>

where

    Y: for<'a> Yokeable<'a>,

    for<'a> YokeTraitHack<<Y as Yokeable<'a>>::Output>: ZeroFrom<'a, <C as Deref>::Target>,

    C: StableDeref + Deref,

    <C as Deref>::Target: 'static,

{

    /// Construct a [`Yoke`]`<Y, C>` from a cart implementing `StableDeref` by zero-copy cloning

    /// the cart to `Y` and then yokeing that object to the cart.

    ///

    /// The type `Y` must implement [`ZeroFrom`]`<C::Target>`. This trait is auto-implemented

    /// on many common types and can be custom implemented or derived in order to make it easier

    /// to construct a `Yoke`.

    ///

    /// # Example

    ///

    /// Attach to a cart:

    ///

    /// ```

    /// use std::borrow::Cow;

    /// use yoke::Yoke;

    ///

    /// let yoke = Yoke::<Cow<'static, str>, String>::attach_to_zero_copy_cart(

    ///     "demo".to_owned(),

    /// );

    ///

    /// assert_eq!("demo", yoke.get());

    /// ```

    pub fn attach_to_zero_copy_cart(cart: C) -> Self {

        Yoke::<Y, C>::attach_to_cart(cart, |c| {

            YokeTraitHack::<<Y as Yokeable>::Output>::zero_from(c).0

        })

    }

}