openFenceAfter function

FenceOpen? openFenceAfter(Iterable<String> lines)

Whether a fence opened in lines is still open after the last line.

The one fence-tracking loop shared by the parser's neighbours (segment splitting, the streaming reveal), so they agree with the parser about where a fence ends.

Fences inside a block quote count: > ```bash opens one, and it closes with its closing line or when the quote ends.

Implementation

FenceOpen? openFenceAfter(Iterable<String> lines) {
  FenceOpen? open;
  var depth = 0;
  for (final line in lines) {
    final current = open;
    final lineDepth = quoteDepth(line);
    if (current != null && lineDepth >= depth) {
      if (isFenceClose(unquoted(line), current)) {
        open = null;
      }
      continue;
    }
    open = fenceOpen(unquoted(line));
    depth = lineDepth;
  }
  return open;
}