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#![cfg_attr(feature = "no_std", no_std)]

#[macro_use]
extern crate cfg_if;

cfg_if! (
    if #[cfg(feature="no_std")] {
        use core::str::FromStr;
    } else {
        use std::str::FromStr;
    }
);
mod char;
mod int;

pub use char::TryFromIntToCharError;
pub use int::TryFromIntError;

pub trait TryFrom<T>: Sized {
    type Err;
    fn try_from(T) -> Result<Self, Self::Err>;
}

pub trait TryInto<T>: Sized {
    type Err;
    fn try_into(self) -> Result<T, Self::Err>;
}

impl<T, U> TryInto<U> for T
where
    U: TryFrom<T>,
{
    type Err = U::Err;
    fn try_into(self) -> Result<U, U::Err> {
        U::try_from(self)
    }
}

impl<'a, T> TryFrom<&'a str> for T
where
    T: FromStr,
{
    type Err = T::Err;
    fn try_from(string: &'a str) -> Result<Self, Self::Err> {
        T::from_str(string)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn should_have_try_from_impl_for_from_str() {
        let result = u32::try_from("3");
        assert_eq!(result.unwrap(), 3)
    }

    #[test]
    fn should_have_try_from_impl_for_from_str_that_handles_err() {
        let result = u32::try_from("hello");
        assert_eq!(
            format!("{}", result.unwrap_err()),
            "invalid digit found in string"
        )
    }

    #[test]
    fn should_have_try_into_impl_for_from_str() {
        let result: Result<u32, _> = "3".try_into();
        assert_eq!(result.unwrap(), 3)
    }
}

/// Error type used when conversion is infallible.
/// The never type (`!`) will replace this when it is available in stable Rust.
#[derive(Debug, Eq, PartialEq)]
pub enum Void {}