Split String on markers and transform to hit ranges

split-to-ranges.java

String value = "fdkslaöfjs fdskla öfjs{{{{}}}}fjdslkajfs{{{{}}}} fdl söaj {{{{}}}}abc{{{{}}}} fdjksö jk";

String marker = "{{{{}}}}";
String[] parts = value.split(Pattern.quote(marker));

List<Integer> lengths = List.of(parts).stream().map(String::length).collect(Collectors.toList());
int total = 0;
List<Integer> lengths_agg = List.of(parts).stream().map(String::length).map(l -> {total = total + l; return total;}).collect(Collectors.toList());

// https://stackoverflow.com/a/30072617/9360161
public static <T> Stream<List<T>> batches(List<T> source, int length) {
    if (length <= 0) { throw new IllegalArgumentException("length = " + length); }
    int size = source.size();
    if (size <= 0) { return Stream.empty(); }
    int fullChunks = (size - 1) / length;
    return IntStream.range(0, fullChunks + 1).mapToObj(n -> source.subList(n * length, n == fullChunks ? size : (n + 1) * length));
}
List<List<Integer>> groups = batches(lens, 2).collect(Collectors.toList());
groups.remove(groups.size() - 1);

// inclusive indices
List<List<Integer>> ranges = groups.stream().map(l -> List.of(l.get(0) + 1, l.get(1))).collect(Collectors.toList());
List<Integer[]> ranges = groups.stream().map(l -> new int[] {l.get(0) + 1, l.get(1)}).collect(Collectors.toList());
// lengths
List<Integer[]> ranges = groups.stream().map(l -> new int[] {l.get(0) + 1, l.get(1) - l.get(0)}).collect(Collectors.toList());