use std::fmt::Display;
use crate::*;
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, ParseAsInline)]
pub struct U63(u64);
impl U63 {
pub fn from_u64(n: u64) -> crate::Result<Self> {
if n < (1 << 63) {
Ok(Self(n))
} else {
Err(Error::UnsupportedLength)
}
}
pub fn as_usize(self) -> crate::Result<usize> {
self.0.try_into().map_err(|_| Error::UnsupportedLength)
}
pub fn len_of<T>(v: &[T]) -> Self {
Self::from_u64(v.len() as _).expect("this is unreasonable to store in memory")
}
}
impl ToOutput for U63 {
fn to_output(&self, output: &mut impl Output) {
if self.0 < 128 {
(self.0 as u8).to_output(output);
} else {
let mut bytes = self.0.to_be_bytes();
bytes[0] ^= 128;
bytes.to_output(output);
}
}
}
impl InlineOutput for U63 {}
impl Tagged for U63 {}
impl ListHashes for U63 {}
impl Topological for U63 {}
impl<I: ParseInput> ParseInline<I> for U63 {
fn parse_inline(input: &mut I) -> crate::Result<Self> {
let mut bytes = [0; 8];
input.read(&mut bytes[..1])?;
Ok(Self(if bytes[0] & 128 == 0 {
bytes[0] as u64
} else {
bytes[0] ^= 128;
input.read(&mut bytes[1..])?;
let n = u64::from_be_bytes(bytes);
if n < 128 {
return Err(Error::OutOfBounds);
}
n
}))
}
}
impl ByteOrd for U63 {
fn bytes_cmp(&self, other: &Self) -> Ordering {
self.cmp(other)
}
}
impl SignificantLength for U63 {}
#[test]
fn reparse_u63_100_000() -> crate::Result<()> {
(0..100_000).try_for_each(|n| {
assert_eq!(U63::from_u64(n)?.reparse()?.0, n);
Ok(())
})
}
impl Display for U63 {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
self.0.fmt(f)
}
}