Rust Requires Chilkat v11.1.0+

Regular Expression with Named Capture Groups

See more Regular Expressions Examples

Demonstrates regular expressions with named capture groups.

See the sample code below.

Note: Chilkat uses PCRE2. See PCRE2 Regular Expressions
Also see: PCRE2 Performance

In PCRE2, named capture groups allow you to assign a name to a capturing group, making it easier to reference by name instead of number.

Syntax

(?<name>pattern)

or

(?'name'pattern)

Example

(?<first>\w+)\s+(?<last>\w+)

Applied to:

"John Smith"

Produces:

• first: John
• last: Smith

Rust

let subject = "John Smith".to_string();
let pattern = "(?<first>\\w+)\\s+(?<last>\\w+)".to_string();

let sb = chilkat::StringBuilder::new();
let _ = sb.append(&subject);

let json = chilkat::JsonObject::new();
json.set_emit_compact(false);

let timeout_ms = 2000;
let num_matches = sb.regex_match(&pattern, &json, timeout_ms);
if num_matches < 0 {
    // Probably an error in the regular expression.
    // Suggestion: Use AI to help create and/or diagnose regular expressions.
    println!("{}", sb.last_error_text());
    return;
}

// Examine the matches:
println!("{}", json.emit().unwrap_or_default());

// Here is the JSON showing the matches.
// Important:  Capture group 0 always contains the entire match — that is, the portion of the input string that matches the full regular expression.

// {
//   "named": {
//     "first": 1,
//     "last": 2
//   },
//   "match": [
//     {
//       "group": [
//         {
//           "cap": "John Smith",
//           "idx": 0,
//           "len": 10
//         },
//         {
//           "cap": "John",
//           "idx": 0,
//           "len": 4
//         },
//         {
//           "cap": "Smith",
//           "idx": 5,
//           "len": 5
//         }
//       ]
//     }
//   ]
// }

// The capture group index is obtained by looking up the name in the JSON result.
// For example:

json.set_i(json.int_of("named.first"));
println!("first: {}", json.string_of("match[0].group[i].cap").unwrap_or_default());

json.set_i(json.int_of("named.last"));
println!("last: {}", json.string_of("match[0].group[i].cap").unwrap_or_default());

// Output is: 

// first: John
// last: Smith