treeSitterCharacterRangeSetContains function

bool treeSitterCharacterRangeSetContains(List<TreeSitterCharacterRange> ranges, int lookahead)

Exact binary-search contract of Tree-sitter 0.25.10 set_contains.

Native callers supply a non-empty array sorted by both endpoints. Invalid inputs are rejected rather than reproducing native out-of-bounds access.

Implementation

bool treeSitterCharacterRangeSetContains(
  List<TreeSitterCharacterRange> ranges,
  int lookahead,
) {
  if (ranges.isEmpty) {
    throw ArgumentError.value(ranges, 'ranges', 'must not be empty');
  }
  var index = 0;
  var size = ranges.length;
  while (size > 1) {
    final halfSize = size ~/ 2;
    final midIndex = index + halfSize;
    final range = ranges[midIndex];
    if (lookahead >= range.start && lookahead <= range.end) {
      return true;
    } else if (lookahead > range.end) {
      index = midIndex;
    }
    size -= halfSize;
  }
  final range = ranges[index];
  return lookahead >= range.start && lookahead <= range.end;
}