ic-storage 0.71.1

// Adapted from ic-stable-structures 0.7.2, DFINITY Foundation.
// SPDX-License-Identifier: Apache-2.0
// See the package LICENSE-APACHE and docs/storage/icss-source.json.
use std::borrow::Cow;
/// Private trapping codec contract. Every encoder must enforce `BOUND` before
/// returning bytes. Production implementations enter through the adapter's
/// checked public codec, so collection engines must not repeat that validation.
pub trait Storable {
    fn to_bytes(&self) -> Cow<'_, [u8]>;
    fn into_bytes(self) -> Vec<u8>;
    fn from_bytes(bytes: Cow<[u8]>) -> Self;
    const BOUND: Bound;
}

pub use crate::storable::Bound;

impl Bound {
    pub(crate) const fn max_size(self) -> u32 {
        if let Self::Bounded { max_size, .. } = self {
            max_size
        } else {
            panic!("Cannot get max size of unbounded type.");
        }
    }
    pub(crate) const fn is_fixed_size(self) -> bool {
        if let Self::Bounded { is_fixed_size, .. } = self {
            is_fixed_size
        } else {
            false
        }
    }
}

pub struct Bounds {
    pub max_size: u32,
    pub is_fixed_size: bool,
}
pub const fn bounds<A: Storable>() -> Bounds {
    if let Bound::Bounded {
        max_size,
        is_fixed_size,
    } = A::BOUND
    {
        Bounds {
            max_size,
            is_fixed_size,
        }
    } else {
        panic!("Cannot get bounds of unbounded type.");
    }
}

pub const fn bytes_to_store_size_bounded(bounds: &Bounds) -> u32 {
    if bounds.is_fixed_size {
        0
    } else {
        bytes_to_store_size(bounds.max_size)
    }
}

const fn bytes_to_store_size(bytes_size: u32) -> u32 {
    if bytes_size <= 0xff {
        1
    } else if bytes_size <= 0xffff {
        2
    } else {
        4
    }
}