tiberius-ng 0.13.1

A TDS (Microsoft SQL Server) driver for Rust — actively-maintained community continuation of tiberius
Documentation 
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use std::fmt::{Display, Write};

pub(crate) trait IteratorJoin {
    fn join(self, sep: &str) -> String;
}

impl<T, I> IteratorJoin for T
where
    T: Iterator<Item = I>,
    I: Display,
{
    fn join(mut self, sep: &str) -> String {
        let (lower_bound, _) = self.size_hint();
        let mut out = String::with_capacity(sep.len() * lower_bound);

        if let Some(first_item) = self.next() {
            write!(out, "{}", first_item).unwrap();
        }

        for item in self {
            out.push_str(sep);
            write!(out, "{}", item).unwrap();
        }

        out
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn join_interleaves_separator_between_elements() {
        let joined = [1, 2, 3].into_iter().join(", ");
        assert_eq!(joined, "1, 2, 3");
    }

    #[test]
    fn join_single_element_has_no_separator() {
        let joined = std::iter::once("only").join(", ");
        assert_eq!(joined, "only");
    }
}