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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 std::any::type_name;
use crate::private::cast::error::CastError;
use crate::private::cast::{get_caster, CastFrom};
pub trait CastBox
{
/// Casts a `Box` with `Self` into a `Box` with `Dest`.
fn cast<Dest: ?Sized + 'static>(self: Box<Self>) -> Result<Box<Dest>, CastError>;
}
/// A blanket implementation of `CastBox` for traits extending `CastFrom`.
impl<CastFromSelf: ?Sized + CastFrom> CastBox for CastFromSelf
{
fn cast<Dest: ?Sized + 'static>(self: Box<Self>) -> Result<Box<Dest>, CastError>
{
let caster =
get_caster::<Dest>((*self).type_id()).map_err(CastError::GetCasterFailed)?;
(caster.cast_box)(self.box_any()).map_err(|err| CastError::CastFailed {
source: err,
from: type_name::<Self>(),
to: type_name::<Dest>(),
})
}
}
#[cfg(test)]
mod tests
{
use std::any::Any;
use std::fmt::{Debug, Display};
use super::*;
use crate::test_utils::subjects;
#[test]
fn can_cast_box()
{
let concrete_ninja = Box::new(subjects::Ninja);
let abstract_ninja: Box<dyn subjects::INinja> = concrete_ninja;
let debug_ninja_result = abstract_ninja.cast::<dyn Debug>();
assert!(debug_ninja_result.is_ok());
}
#[test]
fn cannot_cast_box_wrong()
{
let concrete_ninja = Box::new(subjects::Ninja);
let abstract_ninja: Box<dyn subjects::INinja> = concrete_ninja;
let display_ninja_result = abstract_ninja.cast::<dyn Display>();
assert!(matches!(
display_ninja_result,
Err(CastError::GetCasterFailed(_))
));
}
#[test]
fn can_cast_box_from_any()
{
let concrete_ninja = Box::new(subjects::Ninja);
let any_ninja: Box<dyn Any> = concrete_ninja;
let debug_ninja_result = any_ninja.cast::<dyn Debug>();
assert!(debug_ninja_result.is_ok());
}
}
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