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// Copyright (c) The Libra Core Contributors
// SPDX-License-Identifier: Apache-2.0

//! `Nibble` represents a four-bit unsigned integer.

use proptest::prelude::*;
use serde::{Deserialize, Serialize};
use std::fmt;

#[derive(Clone, Copy, Debug, Hash, Eq, PartialEq, Ord, PartialOrd, Serialize, Deserialize)]
pub struct Nibble(u8);

impl From<u8> for Nibble {
    fn from(nibble: u8) -> Self {
        assert!(nibble < 16, "Nibble out of range: {}", nibble);
        Self(nibble)
    }
}

impl From<Nibble> for u8 {
    fn from(nibble: Nibble) -> Self {
        nibble.0
    }
}

impl fmt::LowerHex for Nibble {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{:x}", self.0)
    }
}

impl Arbitrary for Nibble {
    type Parameters = ();
    type Strategy = BoxedStrategy<Self>;

    fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
        (0..16u8).prop_map(Self::from).boxed()
    }
}