List getTargetMatchedRanges()

in lib/src/license_detection/token_matcher.dart [127:182]

• 41 lines of code
• 8 McCabe index (conditional complexity)

List<MatchRange> getTargetMatchedRanges(
  LicenseWithNGrams knownLicense,
  LicenseWithNGrams unknownLicense,
  int n,
) {
  var offsetMap = <int, List<MatchRange>>{};
  var matches = <MatchRange>[];

  for (var tgtChecksum in unknownLicense.nGrams) {
    var srcChecksums = knownLicense.checksumMap[tgtChecksum.checksum];

    // Check if source contains the checksum.
    if (srcChecksums == null) {
      continue;
    }
    // Iterate over all the trigrams in source having the same checksums.
    for (var i = 0; i < srcChecksums.length; i++) {
      var srcChecksum = srcChecksums[i];
      final offset = tgtChecksum.start - srcChecksum.start;

      // Check if this source checksum extend the last match
      // and update the last match for this offset accordingly.
      var matches = offsetMap[offset];
      if (matches != null && (matches.last.input.end == tgtChecksum.end - 1)) {
        matches.last = matches.last.update(
          inputEnd: tgtChecksum.end,
          srcEnd: srcChecksum.end,
        );
        offsetMap[offset] = matches;
        continue;
      }

      // Add new instance of matchRange if doesn't extend the last
      // match of the same offset.
      offsetMap.putIfAbsent(offset, () => []).add(
            MatchRange(Range(tgtChecksum.start, tgtChecksum.end),
                Range(srcChecksum.start, srcChecksum.end), n),
          );
    }
  }

  for (var list in offsetMap.values) {
    // Update the token count of match range.
    for (var match in list) {
      final start = match.input.start;
      final end = match.input.end;
      match = match.update(newClaim: end - start);
      matches.add(match);
    }
  }

  // Sort the matches based on the number of tokens covered in match
  // range in descending order.
  matches.sort(_compareTokenCount);
  return List.unmodifiable(matches);
}