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use std::{convert::TryFrom, str::FromStr};
use crate::{oid, Kind, ObjectId};
impl TryFrom<u8> for Kind {
type Error = u8;
fn try_from(value: u8) -> Result<Self, Self::Error> {
Ok(match value {
1 => Kind::Sha1,
unknown => return Err(unknown),
})
}
}
impl FromStr for Kind {
type Err = String;
fn from_str(s: &str) -> Result<Self, Self::Err> {
Ok(match s {
"sha1" | "SHA1" => Kind::Sha1,
other => return Err(other.into()),
})
}
}
impl std::fmt::Display for Kind {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Kind::Sha1 => f.write_str("SHA1"),
}
}
}
impl Kind {
/// Returns the shortest hash we support.
#[inline]
pub const fn shortest() -> Self {
Self::Sha1
}
/// Returns the longest hash we support.
#[inline]
pub const fn longest() -> Self {
Self::Sha1
}
/// Returns a buffer suitable to hold the longest possible hash in hex.
#[inline]
pub const fn hex_buf() -> [u8; Kind::longest().len_in_hex()] {
[0u8; Kind::longest().len_in_hex()]
}
/// Returns a buffer suitable to hold the longest possible hash as raw bytes.
#[inline]
pub const fn buf() -> [u8; Kind::longest().len_in_bytes()] {
[0u8; Kind::longest().len_in_bytes()]
}
/// Returns the amount of bytes needed to encode this instance as hexadecimal characters.
#[inline]
pub const fn len_in_hex(&self) -> usize {
match self {
Kind::Sha1 => 40,
}
}
/// Returns the amount of bytes taken up by the hash of this instance.
#[inline]
pub const fn len_in_bytes(&self) -> usize {
match self {
Kind::Sha1 => 20,
}
}
/// Returns the kind of hash that would fit the given `hex_len`, or `None` if there is no fitting hash.
/// Note that `0` as `hex_len` up to 40 always yields `Sha1`.
#[inline]
pub const fn from_hex_len(hex_len: usize) -> Option<Self> {
Some(match hex_len {
0..=40 => Kind::Sha1,
_ => return None,
})
}
/// Converts a size in bytes as obtained by `Kind::len_in_bytes()` into the corresponding hash kind, if possible.
///
/// **Panics** if the hash length doesn't match a known hash.
///
/// NOTE that this method isn't public as it shouldn't be encouraged to assume all hashes have the same length.
/// However, if there should be such a thing, our `oid` implementation will have to become an enum and it's pretty breaking
/// to the way it's currently being used as auto-dereffing doesn't work anymore. Let's hope it won't happen.
// TODO: make 'const' once Rust 1.57 is more readily available in projects using 'gitoxide'.
#[inline]
pub(crate) fn from_len_in_bytes(bytes: usize) -> Self {
match bytes {
20 => Kind::Sha1,
_ => panic!("BUG: must be called only with valid hash lengths produced by len_in_bytes()"),
}
}
/// Create a shared null-id of our hash kind.
#[inline]
pub fn null_ref(&self) -> &'static oid {
match self {
Kind::Sha1 => oid::null_sha1(),
}
}
/// Create an owned null-id of our hash kind.
#[inline]
pub const fn null(&self) -> ObjectId {
match self {
Kind::Sha1 => ObjectId::null_sha1(),
}
}
}
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