//! Replaces occurrences of `:name:` with the actual emoji for `name` in text.

//!

//! # Usage

//!

//! ```sh

//! $ echo "launch :rocket:" | cargo run --example replace

//! launch 🚀

//! ```

use std::io;

use std::io::prelude::*;

use std::io::BufWriter;

fn main() -> io::Result<()> {

let stdin = {

let mut buf = String::new();

io::stdin().read_to_string(&mut buf)?;

buf

};

replace(&stdin, BufWriter::new(io::stdout()))

}

fn replace(mut s: &str, mut o: impl Write) -> io::Result<()> {

// The meaning of the index values is as follows.

//

// : r o c k e t :

// ^ ^ ^ ^

// i m n j

//

// i..j gives ":rocket:"

// m..n gives "rocket"

while let Some((i, m, n, j)) = s

.find(':')

.map(|i| (i, i + 1))

.and_then(|(i, m)| s[m..].find(':').map(|x| (i, m, m + x, m + x + 1)))

{

match emojis::get_by_shortcode(&s[m..n]) {

Some(emoji) => {

// Output everything preceding, except the first colon.

o.write_all(&s.as_bytes()[..i])?;

// Output the emoji.

o.write_all(emoji.as_bytes())?;

// Update the string to past the last colon.

s = &s[j..];

}

None => {

// Output everything preceding but not including the colon.

o.write_all(&s.as_bytes()[..n])?;

// Update the string to start with the last colon.

s = &s[n..];

}

}

}

o.write_all(s.as_bytes())

}

#[test]

fn smoke() {

let tests = [

("launch nothing", "launch nothing"),

("launch :rocket: something", "launch 🚀 something"),

("? :unknown: emoji", "? :unknown: emoji"),

("::very:naughty::", "::very:naughty::"),

(":maybe:rocket:", ":maybe🚀"),

(":rocket::rocket:", "🚀🚀"),

];

for (i, o) in tests {

let mut v = Vec::new();

replace(i, &mut v).unwrap();

assert_eq!(std::str::from_utf8(&v).unwrap(), o);

}

}