Dart Requires Chilkat v11.1.0+

Regular Expression with Multiple Matches and Named Capture Groups

See more Regular Expressions Examples

Demonstrates regular expressions with named capture groups and multiple matches. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  final sb = CkStringBuilder();
  final crlf = true;
  sb.appendLine('Name: John Smith', crlf);
  sb.appendLine('Name: Jack Johnson', crlf);
  sb.appendLine('Name: Mary Adams', crlf);

  print(sb.getAsString());

  // We have the following string:
  // Name: John Smith
  // Name: Jack Johnson
  // Name: Mary Adams

  final pattern = 'Name:\\s+(?<first>\\w+)\\s+(?<last>\\w+)';
  final json = CkJsonObject();
  json.emitCompact = false;

  final timeoutMs = 2000;
  final numMatches = sb.regexMatch(pattern, json, timeoutMs);
  if (numMatches < 0) {
    // Probably an error in the regular expression.
    // Suggestion: Use AI to help create and/or diagnose regular expressions.
    print(sb.lastErrorText);
    return;
  }

  // Examine the matches:
  print(json.emit());

  // 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": "Name: John Smith",
  //           "idx": 0,
  //           "len": 16
  //         },
  //         {
  //           "cap": "John",
  //           "idx": 6,
  //           "len": 4
  //         },
  //         {
  //           "cap": "Smith",
  //           "idx": 11,
  //           "len": 5
  //         }
  //       ]
  //     },
  //     {
  //       "group": [
  //         {
  //           "cap": "Name: Jack Johnson",
  //           "idx": 18,
  //           "len": 18
  //         },
  //         {
  //           "cap": "Jack",
  //           "idx": 24,
  //           "len": 4
  //         },
  //         {
  //           "cap": "Johnson",
  //           "idx": 29,
  //           "len": 7
  //         }
  //       ]
  //     },
  //     {
  //       "group": [
  //         {
  //           "cap": "Name: Mary Adams",
  //           "idx": 38,
  //           "len": 16
  //         },
  //         {
  //           "cap": "Mary",
  //           "idx": 44,
  //           "len": 4
  //         },
  //         {
  //           "cap": "Adams",
  //           "idx": 49,
  //           "len": 5
  //         }
  //       ]
  //     }
  //   ]
  // }

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

  final idxFirst = json.intOf('named.first');
  final idxLast = json.intOf('named.last');

  var i = 0;
  final matchCount = json.sizeOfArray('match');
  while (i < matchCount) {
    print('Match ${i + 1}:');
    json.i = i;

    json.j = idxFirst;
    print('first: ${json.stringOf('match[i].group[j].cap')}');

    json.j = idxLast;
    print('first: ${json.stringOf('match[i].group[j].cap')}');

    print('');
    i++;
  }

  // Output is: 

  // Match 1:
  // first: John
  // first: Smith
  // 
  // Match 2:
  // first: Jack
  // first: Johnson
  // 
  // Match 3:
  // first: Mary
  // first: Adams
}