Struct Joiner

Source

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§

Source §

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

Source

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

Create a Joiner object.

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

Source

pub fn into_string(self) -> String
where I::Item: Display,

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 8)

3pub fn reverse_words(s: impl AsRef<str>) -> String {
4    s.as_ref()
5        .split_whitespace()
6        .map(|s| s.chars().rev().join(""))
7        .join(" ")
8        .into_string()
9}
10
11fn main() {
12    println!("{}", reverse_words("foo bar baz"));
13
14    println!(
15        "{}",
16        "foo bar baz"
17            .split_whitespace()
18            .map(|s| s.chars().rev().join(""))
19            .join(" ")
20    );
21
22    println!(
23        "{}",
24        "foo bar baz"
25            .split_whitespace()
26            .map(|s| s
27                .chars()
28                .rev()
29                .map(|c| char::from_u32(c as u32 + 1).unwrap_or('?'))
30                .join(""))
31            .join(" ")
32    );
33
34    // inefficient temporary strings
35    println!(
36        "{}",
37        "foo bar baz"
38            .split_whitespace()
39            .map(|s| s.chars().rev().map(|c| format!("<{c}>")).join(""))
40            .join(" ")
41    );
42
43    // inefficient temporary strings
44    println!(
45        "{}",
46        std::env::args()
47            .map(|s| s.chars().rev().collect::<String>())
48            .join(" ")
49            .into_string()
50    );
51}

Source

pub fn write_fmt<W: Write>(self, writer: W) -> Result
where I::Item: Display,

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

Source

pub fn write_io<W: Write>(self, writer: W) -> Result<()>
where I::Item: Display,

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)

6fn main() -> std::io::Result<()> {
7    let mut args = std::env::args().skip(1);
8
9    let filename = args.next().expect(USAGE);
10    let sep = args.next().expect(USAGE);
11
12    let file = File::create(filename)?;
13
14    args.join(sep).write_io(file)?;
15
16    Ok(())
17}

More examples

Hide additional examples

examples/simple.rs (line 12)

3fn main() -> std::io::Result<()> {
4    println!("{}", ["foo", "bar", "baz"].join(", "));
5    println!("{}", ['a', 'b', 'c'].join(", "));
6    println!(
7        "{}",
8        ["foo".to_owned(), "bar".to_owned(), "baz".to_owned()].join(", ")
9    );
10    println!("{}", vec![1, 2, 3].iter().cycle().take(5).join(", "));
11    println!("{}", "äüö".chars().join(' '));
12    std::env::args().join(", ").write_io(std::io::stdout())?;
13    println!();
14
15    // inefficient temporary string
16    let str: String = std::env::args().join(", ").into();
17    println!("{}", str);
18
19    Ok(())
20}