levenshtein function

int levenshtein(List<Diff> diffs)

Compute the Levenshtein distance; the number of inserted, deleted or substituted characters.

diffs is a List of Diff objects.

Returns the number of changes.

Implementation

int levenshtein(List<Diff> diffs) {
  int levenshtein = 0;
  int insertions = 0;
  int deletions = 0;
  for (Diff aDiff in diffs) {
    switch (aDiff.operation) {
    case DIFF_INSERT:
      insertions += aDiff.text.length;
      break;
    case DIFF_DELETE:
      deletions += aDiff.text.length;
      break;
    case DIFF_EQUAL:
      // A deletion and an insertion is one substitution.
      levenshtein += max<int>(insertions, deletions);
      insertions = 0;
      deletions = 0;
      break;
    }
  }
  levenshtein += max<int>(insertions, deletions);
  return levenshtein;
}