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use core::mem::ManuallyDrop; | |
use core::str::from_utf8; | |
const SIZE_LIMIT: usize = 40; | |
trait Name { | |
const NAME: [u8; SIZE_LIMIT]; | |
const NAME_LEN: usize; | |
fn name() -> &'static str { | |
from_utf8(&Self::NAME[..Self::NAME_LEN]).expect("bad utf-8") | |
} | |
} | |
macro_rules! name { | |
(new $($tt:tt)*) => { | |
const NAME: [u8; SIZE_LIMIT] = { | |
let mut out = [0u8; SIZE_LIMIT]; | |
let mut offset = 0; | |
name!(@data(out, offset); $($tt)*); | |
out | |
}; | |
const NAME_LEN: usize = 0 + name!(@size; $($tt)*); | |
}; | |
(@size;) => { | |
0 | |
}; | |
(@size; fixed($expr:expr) $($tt:tt)*) => { | |
$expr.len() + name!(@size; $($tt)*) | |
}; | |
(@size; nameof($expr:ty) $($tt:tt)*) => { | |
<$expr>::NAME_LEN + name!(@size; $($tt)*) | |
}; | |
(@data($out:ident, $offset:ident);) => {}; | |
(@data($out:ident, $offset:ident); fixed($expr:expr) $($tt:tt)*) => { | |
{ | |
let data = $expr.as_bytes(); | |
let mut doffset = 0; | |
while doffset < data.len() { | |
$out[$offset] = data[doffset]; | |
$offset += 1; | |
doffset += 1; | |
} | |
} | |
name!(@data($out, $offset); $($tt)*) | |
}; | |
(@data($out:ident, $offset:ident); nameof($expr:ty) $($tt:tt)*) => { | |
{ | |
let mut doffset = 0; | |
while doffset < <$expr>::NAME_LEN { | |
$out[$offset] = <$expr>::NAME[doffset]; | |
$offset += 1; | |
doffset += 1; | |
} | |
} | |
name!(@data($out, $offset); $($tt)*) | |
}; | |
} | |
impl Name for u8 { | |
name!(new fixed("uint8")); | |
} | |
impl Name for u32 { | |
name!(new fixed("uint32")); | |
} | |
impl<T: Name> Name for Vec<T> { | |
name!(new nameof(T) fixed("[]")); | |
} | |
impl<A: Name, B: Name> Name for (A, B) { | |
name!(new fixed("(") nameof(A) fixed(",") nameof(B) fixed(")")); | |
} | |
fn main() { | |
dbg!(<Vec<u8>>::name()); | |
dbg!(<Vec<u32>>::name()); | |
dbg!(<(Vec<u32>, (u32, Vec<u8>))>::name()); | |
} |
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