linearSearchBy<E> function

int linearSearchBy<E>(List<E> list, EqualityTest<E> test, { int? start, int? count, })

Returns the first index where the test is true in the list, otherwise -1.

You can control the range to search using the start and count parameters.

• If start is given, search start there and go towards the end of the list.
• If start is not below the length of the list, -1 will be returned.
• If start is negative, search starts at start + count or 0, whichever is greater.
• If the count parameter is given, it will check up to count numbers of items.
• If count is negative, -1 will be returned.

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Complexity: Time O(n) | Space O(1)

Implementation

int linearSearchBy<E>(
  List<E> list,
  EqualityTest<E> test, {
  int? start,
  int? count,
}) {
  int l, h;
  int n = list.length;

  // determine range [l, h)
  l = start ?? 0;
  h = n;
  if (count != null) {
    if (count < 0) return -1;
    h = l + count;
    if (h > n) h = n;
  }
  if (l < 0) l = 0;

  // forward loop in range [l, h)
  for (; l < h; ++l) {
    if (test(list[l])) {
      return l;
    }
  }

  return -1;
}