设计意图

一个字符串分割器

  1. pub struct StrSplit<'h, 'd> {
  2.     reminder: Option<&'h str>,
  3.     delimiliter: &'d str,
  4. }
  6. #[allow(dead_code)]
  7. impl<'h, 'd> StrSplit<'h, 'd> {
  8.     pub fn new(s: &'h str, delimiliter: &'d str) -> Self {
  9.         StrSplit {
  10.             reminder: Some(s),
  11.             delimiliter,
  12.         }
  13.     }
  14. }
  17. impl<'h, 'd> Iterator for StrSplit<'h, 'd> {
  18.     type Item = &'h str;
  20.     fn next(&mut self) -> Option<Self::Item> {
  21.         let reminder = self.reminder.as_mut()?;
  22.         if let Some(b) = reminder.find(self.delimiliter) {
  23.             let util = &reminder[..b];
  24.             *reminder = &reminder[b + self.delimiliter.len()..];
  25.             Some(util)
  26.         } else {
  27.             self.reminder.take()
  28.         }
  29.     }
  30. }
  32. #[allow(dead_code)]
  33. fn until_char<'a>(s: &'a str, c: char) -> &'a str {
  34.     let de = format!("{}", c);
  35.     StrSplit::new(s, &de).next().expect("not found")
  36. }

结构体 StrSplit包含两个生命周期，’h ‘d 其中h和被切割的str生命周期一致。而在迭代器中迭代器返回的Item同样是h生命周期。因此直接用传入的str构建item迭代项。

until中传入短生命周期的de也没关系