notecrumbs

a nostr opengraph server build on nostrdb and egui
git clone git://jb55.com/notecrumbs
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abbrev.rs (991B)

      1 #[inline]
      2 fn floor_char_boundary(s: &str, index: usize) -> usize {
      3     if index >= s.len() {
      4         s.len()
      5     } else {
      6         let lower_bound = index.saturating_sub(3);
      7         let new_index = s.as_bytes()[lower_bound..=index]
      8             .iter()
      9             .rposition(|b| is_utf8_char_boundary(*b));
     10 
     11         // SAFETY: we know that the character boundary will be within four bytes
     12         unsafe { lower_bound + new_index.unwrap_unchecked() }
     13     }
     14 }
     15 
     16 #[inline]
     17 fn is_utf8_char_boundary(c: u8) -> bool {
     18     // This is bit magic equivalent to: b < 128 || b >= 192
     19     (c as i8) >= -0x40
     20 }
     21 
     22 const ABBREV_SIZE: usize = 10;
     23 
     24 pub fn abbrev_str(name: &str) -> String {
     25     if name.len() > ABBREV_SIZE {
     26         let closest = floor_char_boundary(name, ABBREV_SIZE);
     27         format!("{}...", &name[..closest])
     28     } else {
     29         name.to_owned()
     30     }
     31 }
     32 
     33 pub fn abbreviate<'a>(text: &'a str, len: usize) -> &'a str {
     34     let closest = floor_char_boundary(text, len);
     35     &text[..closest]
     36 }