CODEWITHSUNDEEP
dart
dls49
dls49

Reputation: 67

Dart RegExp not returning matches

I have a tested regular expression to split , delimited phrases in a string, except where the , is in brackets.

Testing the regular expression with this string in https://regex101.com/r/COMj2b/1 with ECMAScript flavour gives desired matches. No matches are printed in my Dart version.

Any guidance much appreciated!

void main() {
  String s = """Joe's Jazz Band (Ensemble), Fred Dagg (Guitar), Tommy Tucker (Horn, Clarinet), The Pied Piper (Whistle)""";
  RegExp re = RegExp(r'([^,(]*\([^)]*\))*[^,]*(,|$)');

  List li = s.split(re);
  print('$li');
}

My Dart code prints [,,,].

I expected it to print: ['Joe's Jazz Band (Ensemble)', 'Fred Dagg (Guitar)', 'Tommy Tucker (Horn, Clarinet)', 'The Pied Piper (Whistle)']

Upvotes: 2

Views: 256

Answers (2)

attdona
attdona

Reputation: 18923

split does not return the matches but splits the string at matches of pattern and returns a list of substrings.

Supposing that the separator is a ) bracket followed by zero or more spaces and a comma, this works with split: 

void main() {
  String s = """Joe's Jazz Band (Ensemble), Fred Dagg (Guitar), Tommy Tucker (Horn, Clarinet), The Pied Piper (Whistle)""";
  RegExp re = RegExp(r'\)[ \t]*,');

  Iterable li = s.split(re).map((item) => item.endsWith(")") ? item.trim() : "$item)".trim());

  li.forEach((item) => print('$item'));

}

Note that it is necessary to add a ) at the last splitted element. The trim() is not necessary at less you want to remove leading and trailing whitespaces.

Upvotes: 1

Denis Sablukov
Denis Sablukov

Reputation: 3690

As said @attdona split doesn't return matches, so if you want to get matches, use something like that:

void main() {
  String s = """Joe's Jazz Band (Ensemble), Fred Dagg (Guitar), Tommy Tucker (Horn, Clarinet), The Pied Piper (Whistle)""";
  RegExp re = RegExp(r'([^,(]*\([^)]*\))*[^,]*(,|$)');

  List l = re.allMatches(s).toList();
  List<String> li = new List();
  for(Match e in l) {
    li.add(e.group(0));
  }

  print('$li');
}

Upvotes: 0

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