CODEWITHSUNDEEP
regexrust
qdwang
qdwang

Reputation: 445

How to get the index of matching group in the regex crate?

I only find one way is that using a Captures iter to check which index is Some(..).

let re = Regex::new(r"([a-zA-Z_][a-zA-Z0-9]*)|([0-9]+)|(\.)|(=)").unwrap();

for cap in re.captures_iter("asdf.aeg = 34") {
    let mut index = 0;
    for (i, name) in cap.iter().enumerate() {
        if i == 0 {continue}
        if let Some(_) = name {index = i; break;}
    }
    println!("group {:?}, match {:?}", index, cap.at(index).unwrap());
}

Is there a proper way?

Upvotes: 2

Views: 2963

Answers (1)

Vladimir Matveev
Vladimir Matveev

Reputation: 128011

I think your code is almost as close as you can get. Here is a slightly more idiomatic version:

let re = Regex::new(r"([a-zA-Z_][a-zA-Z0-9]*)|([0-9]+)|(\.)|(=)").unwrap();

for cap in re.captures_iter("asdf.aeg = 34") {
    let index = cap.iter().enumerate()
        .skip(1)                  // skip the first group
        .find(|t| t.1.is_some())  // find the first `Some`
        .map(|t| t.0)             // extract the index
        .unwrap_or(0);            // get the index
    println!("group {:?}, match {:?}", index, cap.get(index).unwrap().as_str());
}

Upvotes: 3

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