textFingerprint function

int textFingerprint(String text)

Simple 32-bit fingerprint: hash of word shingles. text split on non-letters. Audited: 2026-06-12 11:26 EDT

Implementation

int textFingerprint(String text) {
  // Lowercase and split on any non-alphanumeric run so punctuation/casing do not
  // change the fingerprint; drop one-character tokens, which are mostly noise and
  // dilute the signal.
  final List<String> words = text
      .toLowerCase()
      .split(RegExp(r'[^a-z0-9]+'))
      .where((s) => s.length > 1)
      .toList();
  if (words.isEmpty) return 0;
  // Fold each word's hash into the fingerprint, mixing in its position
  // (index * prime) so that the same words in a different order produce a
  // different fingerprint — the fingerprint is order-sensitive by design.
  int fp = 0;
  for (final MapEntry<int, String> entry in words.asMap().entries) {
    fp ^= (entry.value.hashCode + entry.key * _kFingerprintPrime);
  }
  return fp;
}