use crate::Error;

use rand_core::{TryCryptoRng, TryRng};

/// A [`TryRng`] interface over the system's preferred random number source

///

/// This is a zero-sized struct. It can be freely constructed with just `SysRng`.

///

/// This struct is also available as [`rand::rngs::SysRng`] when using [rand].

///

/// # Usage example

///

/// `SysRng` implements [`TryRng`]:

/// ```

/// use getrandom::{rand_core::TryRng, SysRng};

///

/// let mut key = [0u8; 32];

/// SysRng.try_fill_bytes(&mut key).unwrap();

/// ```

///

/// Using it as an [`Rng`] is possible using [`UnwrapErr`]:

/// ```

/// use getrandom::rand_core::{Rng, UnwrapErr};

/// use getrandom::SysRng;

///

/// let mut rng = UnwrapErr(SysRng);

/// let random_u64 = rng.next_u64();

/// ```

///

/// [rand]: https://crates.io/crates/rand

/// [`rand::rngs::SysRng`]: https://docs.rs/rand/latest/rand/rngs/struct.SysRng.html

/// [`Rng`]: rand_core::Rng

/// [`UnwrapErr`]: rand_core::UnwrapErr

#[derive(Clone, Copy, Debug, Default)]

pub struct SysRng;

impl TryRng for SysRng {

    type Error = Error;

    #[inline]

    fn try_next_u32(&mut self) -> Result<u32, Error> {

        crate::u32()

    }

    #[inline]

    fn try_next_u64(&mut self) -> Result<u64, Error> {

        crate::u64()

    }

    #[inline]

    fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> {

        crate::fill(dest)

    }

Unexecuted instantiation: <getrandom::sys_rng::SysRng as rand_core::TryRng>::try_fill_bytes

Unexecuted instantiation: <getrandom::sys_rng::SysRng as rand_core::TryRng>::try_fill_bytes

}

impl TryCryptoRng for SysRng {}