Give NewlinePattern a method that returns a configurable splitter on a given string

[jwodder]

• Method name: split()?

• The method takes a &'a str and returns a Splitter<'a> (Name not fixed), which implements DoubleEndedIterator<Item=&'a str> (or just implements IntoIterator returning a separate DoubleEndedIterator type?)

• Splitter has the following methods for configuring its behavior:

  • inclusive(self) -> Self — Causes terminating patterns to be included in the strings yielded by the iterator and once()
  • something for controlling whether a pattern at the end of the input should result in the iterator yielding a final empty string (default: no)
    • This includes yielding just "" when the input is the empty string.
  • limit(self, n: usize) -> Self — cf. str::splitn()
  • once(self) -> Option<(&'a str, &'a str)> — Splits the input string only on the first occurrence of the pattern

Cf. the API of https://crates.io/crates/str_splitter