Created
March 24, 2024 15:19
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| macro_rules! cat { | |
| ($($str:expr),*) => {{ | |
| const LEN: usize = $($str.len() + )* 0; | |
| to_str(&combine::<LEN>(&[$($str),*])) | |
| }}; | |
| } | |
| const fn combine<const LEN: usize>(list: &[&'static str]) -> [u8; LEN] { | |
| let mut bytes = [0; LEN]; | |
| let mut i = 0; | |
| let mut cursor = 0; | |
| while i < list.len() { | |
| let str = list[i].as_bytes(); | |
| // write | |
| { | |
| let mut j = 0; | |
| while j < str.len() { | |
| bytes[cursor + j] = str[j]; | |
| j += 1; | |
| } | |
| } | |
| cursor += str.len(); | |
| i += 1; | |
| } | |
| bytes | |
| } | |
| const fn to_str(bytes: &'static [u8]) -> &'static str { | |
| match std::str::from_utf8(bytes) { | |
| Ok(s) => s, | |
| // `combine` only accept UTF-8 strings | |
| Err(_) => unreachable!(), | |
| } | |
| } | |
| const S1: &'static str = cat!("a", "bc"); | |
| const S2: &'static str = cat!("A", "B", S1); |
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