/// Iterator yielding every line in a string. The line includes newline
/// character(s).
pub struct LinesWithEndings<'a> {
    input: &'a str,
}

impl<'a> LinesWithEndings<'a> {
    pub fn from(input: &'a str) -> LinesWithEndings<'a> {
        LinesWithEndings { input }
    }
}

impl<'a> Iterator for LinesWithEndings<'a> {
    type Item = &'a str;

    #[inline]
    fn next(&mut self) -> Option<&'a str> {
        if self.input.is_empty() {
            return None;
        }
        let split = self
            .input
            .find('\n')
            .map(|i| i + 1)
            .unwrap_or_else(|| self.input.len());
        let (line, rest) = self.input.split_at(split);
        self.input = rest;
        Some(line)
    }
}
