contains function

bool contains(String str, String seed, { bool ignoreCase = false, int minOccurrences = 1, })

Checks if the string contains the seed substring.

Set ignoreCase to true for a case-insensitive match. minOccurrences requires the seed to appear at least that many times.

Note: this is exposed only as a top-level function because String already provides a built-in contains method.

Example:

contains('hello world', 'world'); // true
contains('hello world', 'WORLD', ignoreCase: true); // true
contains('a-a-a', 'a', minOccurrences: 3); // true

Implementation

bool contains(
  String str,
  String seed, {
  bool ignoreCase = false,
  int minOccurrences = 1,
}) {
  if (seed.isEmpty) return false;
  final haystack = ignoreCase ? str.toLowerCase() : str;
  final needle = ignoreCase ? seed.toLowerCase() : seed;
  return needle.allMatches(haystack).length >= minOccurrences;
}