commonCharacters method

Set<String> commonCharacters(
  1. String otherString, {
  2. bool caseSensitive = true,
  3. bool sort = true,
  4. bool includeSpaces = false,
})

Returns a Set of the common characters between the two Strings.

The String is case sensitive & sorted by default.

Example

String foo = 'Hello World';
List<String> commonLetters = foo.commonCharacters('World Hello'); // returns ['H', 'e', 'l', 'o', 'r', 'w', 'd'];

String foo = 'Hello World';
List<String> commonLetters = foo.commonCharacters('World Hello!'); // returns ['H', 'e', 'l', 'o', 'r', 'w', 'd'];

Implementation

Set<String> commonCharacters(
  String otherString, {
  bool caseSensitive = true,
  bool sort = true,
  bool includeSpaces = false,
}) {
  if (this.isBlank) {
    return {};
  }

  String processString(String input) {
    return (caseSensitive ? input : input.toLowerCase())
        .split('')
        .where((char) => includeSpaces || char != ' ')
        .join('');
  }

  final Set<String> commonLettersSet = {};
  final Set<String> otherStringSet =
      processString(otherString).split('').toSet();

  for (final letter in processString(this).split('')) {
    if (otherStringSet.contains(letter)) {
      commonLettersSet.add(letter);
    }
  }

  if (sort) {
    final List<String> sortedList = commonLettersSet.toList()..sort();
    return sortedList.toSet();
  } else {
    return commonLettersSet;
  }
}