src/libs/intertrait/cast/box.rs


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//! Originally from Intertrait by CodeChain
//!
//! <https://github.com/CodeChain-io/intertrait>
//! <https://crates.io/crates/intertrait/0.2.2>
//!
//! Licensed under either of
//!
//! Apache License, Version 2.0 (LICENSE-APACHE or <http://www.apache.org/licenses/LICENSE-2.0>)
//! MIT license (LICENSE-MIT or <http://opensource.org/licenses/MIT>)
//!
//! at your option.
use crate::libs::intertrait::{caster, CastFrom};

pub trait CastBox
{
    /// Casts a box to this trait into that of type `T`. If fails, returns the receiver.
    fn cast<T: ?Sized + 'static>(self: Box<Self>) -> Result<Box<T>, Box<Self>>;
}

/// A blanket implementation of `CastBox` for traits extending `CastFrom`.
impl<S: ?Sized + CastFrom> CastBox for S
{
    fn cast<T: ?Sized + 'static>(self: Box<Self>) -> Result<Box<T>, Box<Self>>
    {
        match caster::<T>((*self).type_id()) {
            Some(caster) => Ok((caster.cast_box)(self.box_any())),
            None => Err(self),
        }
    }
}