Struct join_string::Joiner

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pub struct Joiner<I, S>where
    I: Iterator,
    S: Display,{ /* private fields */ }

Expand description

Helper struct that captures the iterator and separator for later joining.

Implementations§

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impl<I, S> Joiner<I, S>where I: Iterator, S: Display, I::Item: Display,

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pub fn new(iter: I, sep: S) -> Self

Create a Joiner object.

You can use this when implementing your own join() function.

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pub fn into_string(self) -> String

Consumes the backing iterator of a Joiner and returns the joined elements as a new String.

Examples found in repository ?

examples/reverse_words.rs (line 7)

pub fn reverse_words(s: impl AsRef<str>) -> String {
    s.as_ref().split_whitespace()
         .map(|s| s.chars().rev().join(""))
         .join(" ")
         .into_string()
}

fn main() {
    println!("{}", reverse_words("foo bar baz"));

    println!("{}",
        "foo bar baz".split_whitespace()
            .map(|s| s.chars().rev().join(""))
            .join(" "));

    println!("{}",
        "foo bar baz".split_whitespace()
            .map(|s| s.chars().rev().map(|c| char::from_u32(c as u32 + 1u32).unwrap_or('?')).join(""))
            .join(" "));

    // inefficient temporary strings
    println!("{}",
        "foo bar baz".split_whitespace()
            .map(|s| s.chars().rev().map(|c| format!("<{c}>")).join(""))
            .join(" "));

    // inefficient temporary strings
    println!("{}", std::env::args().map(|s| s.chars().rev().collect::<String>()).join(" ").into_string());
}

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pub fn write_fmt<W: Write>(self, writer: W) -> Result

Consumes the backing iterator of a Joiner and writes the joined elements into a std::fmt::Write.

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pub fn write_io<W: Write>(self, writer: W) -> Result<()>

Consumes the backing iterator of a Joiner and writes the joined elements into a std::io::Write.

Examples found in repository ?

examples/file.rs (line 14)

fn main() -> std::io::Result<()> {
    let mut args = std::env::args().skip(1);

    let filename = args.next().expect(USAGE);
    let sep = args.next().expect(USAGE);

    let file = File::create(filename)?;

    args.join(sep).write_io(file)?;

    Ok(())
}

More examples

Hide additional examples

examples/simple.rs (line 9)

fn main() -> std::io::Result<()> {
    println!("{}", ["foo", "bar", "baz"].join(", "));
    println!("{}", ['a', 'b', 'c'].join(", "));
    println!("{}", ["foo".to_owned(), "bar".to_owned(), "baz".to_owned()].join(", "));
    println!("{}", vec![1, 2, 3].iter().cycle().take(5).join(", "));
    println!("{}", "äüö".chars().join(' '));
    std::env::args().join(", ").write_io(std::io::stdout())?;
    println!();

    // inefficient temporary string
    let str: String = std::env::args().join(", ").into();
    println!("{}", str);

    Ok(())
}