Dart Requires Chilkat v11.1.0+

Regular Expression with Multiple Matches and Capture Groups

See more Regular Expressions Examples

Demonstrates a regular expression with multiple matches and capture groups for each match.

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

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  final pattern = 'Name:\\s+(\\w+)\\s+(\\w+),\\s+Email:\\s+(\\S+)';

  final sb = CkStringBuilder();
  final crlf = true;
  sb.appendLine('Name: John Smith, Email: john.smith@example.com', crlf);
  sb.appendLine('Name: Jack Johnson, Email: jack.johnson@example.com', crlf);
  sb.appendLine('Name: Mary Adams, Email: mary.adams@example.com', crlf);

  print(sb.getAsString());

  // We have the following string:
  // Name: John Smith, Email: john.smith@example.com
  // Name: Jack Johnson, Email: jack.johnson@example.com
  // Name: Mary Adams, Email: mary.adams@example.com

  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());

  // This is the JSON with the match information.
  // See the JSON parsing code below to get the matched capture group values.

  // {
  //   "match": [
  //     {
  //       "group": [
  //         {
  //           "cap": "Name: John Smith, Email: john.smith@example.com",
  //           "idx": 0,
  //           "len": 47
  //         },
  //         {
  //           "cap": "John",
  //           "idx": 6,
  //           "len": 4
  //         },
  //         {
  //           "cap": "Smith",
  //           "idx": 11,
  //           "len": 5
  //         },
  //         {
  //           "cap": "john.smith@example.com",
  //           "idx": 25,
  //           "len": 22
  //         }
  //       ]
  //     },
  //     {
  //       "group": [
  //         {
  //           "cap": "Name: Jack Johnson, Email: jack.johnson@example.com",
  //           "idx": 49,
  //           "len": 51
  //         },
  //         {
  //           "cap": "Jack",
  //           "idx": 55,
  //           "len": 4
  //         },
  //         {
  //           "cap": "Johnson",
  //           "idx": 60,
  //           "len": 7
  //         },
  //         {
  //           "cap": "jack.johnson@example.com",
  //           "idx": 76,
  //           "len": 24
  //         }
  //       ]
  //     },
  //     {
  //       "group": [
  //         {
  //           "cap": "Name: Mary Adams, Email: mary.adams@example.com",
  //           "idx": 102,
  //           "len": 47
  //         },
  //         {
  //           "cap": "Mary",
  //           "idx": 108,
  //           "len": 4
  //         },
  //         {
  //           "cap": "Adams",
  //           "idx": 113,
  //           "len": 5
  //         },
  //         {
  //           "cap": "mary.adams@example.com",
  //           "idx": 127,
  //           "len": 22
  //         }
  //       ]
  //     }
  //   ]
  // }

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

  var cap = '';
  var i = 0;
  final matchCount = json.sizeOfArray('match');
  while (i < matchCount) {
    print('Match ${i + 1}:');
    json.i = i;
    var j = 0;
    final numCaptureGroups = json.sizeOfArray('match[i].group');
    while (j < numCaptureGroups) {
      json.j = j;
      cap = json.stringOf('match[i].group[j].cap');
      print('$j: $cap');
      j++;
    }

    i++;
  }

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

  // Output

  // Match 1:
  // 0: Name: John Smith, Email: john.smith@example.com
  // 1: John
  // 2: Smith
  // 3: john.smith@example.com
  // Match 2:
  // 0: Name: Jack Johnson, Email: jack.johnson@example.com
  // 1: Jack
  // 2: Johnson
  // 3: jack.johnson@example.com
  // Match 3:
  // 0: Name: Mary Adams, Email: mary.adams@example.com
  // 1: Mary
  // 2: Adams
  // 3: mary.adams@example.com
}