Function foreach

src/common/values.cpp:205–226

In a single pass, we compute the size of the end result, as well as modify in place the intermediate data structure to build up result as we solve it.

  // in place the intermediate data structure to build up result as we
  // solve it.
  foreach (const Range& range, ranges) {
    // Skip if this range is equivalent to the current range.
    if (range.start == current.start && range.end == current.end) {
      continue;
    }

    // If the current range just needs to be extended on the right.
    if (range.start == current.start && range.end > current.end) {
      current.end = range.end;
    } else if (range.start > current.start) {
      // If we are starting farther ahead, then there are 2 cases:
      if (range.start <= current.end + 1) {
        // 1. Ranges are overlapping and we can merge them.
        current.end = max(current.end, range.end);
      } else {
        // 2. No overlap and we are adding a new range.
        ranges[count - 1] = current;
        ++count;
        current = range;
      }
    }
  }

  // Record the state of the last range into of ranges vector.
  ranges[count - 1] = current;