unscanny

Painless string scanning.

[dependencies]
unscanny = "0.1"

Basically, you'll want to use this crate if it's too much pain to solve your problem with a bare chars() iterator. Speaking more broadly, unscanny is useful in these situations:

• You need to parse simple flat grammars (dates, times, custom stuff, ...) and want an interface that's a bit more convenient to use than a simple char iterator.
• You're hand-writing a tokenizer.

The Scanner keeps an internal cursor, allows you to peek around it, advance it beyond chars or other patterns and easily slice substrings before and after the cursor.

Example

Recognizing and parsing a simple comma separated list of floats.

let mut s = Scanner::new(" +12 , -15.3, 14.3  ");
let mut nums = vec![];
while !s.done() {
    s.eat_whitespace();
    let start = s.cursor();
    s.eat_if(['+', '-']);
    s.eat_while(char::is_ascii_digit);
    s.eat_if('.');
    s.eat_while(char::is_ascii_digit);
    nums.push(s.from(start).parse::<f64>().unwrap());
    s.eat_whitespace();
    s.eat_if(',');
}
assert_eq!(nums, [12.0, -15.3, 14.3]);

Safety

This crate internally uses unsafe code for better performance. However, all unsafe code is documented with justification for why it's safe, all accesses are checked in debug mode and everything is tested.

License

This crate is dual-licensed under the MIT and Apache 2.0 licenses.