tryCreateFootnoteLink static method

Iterable<Node>? tryCreateFootnoteLink(LinkContext context, String text, { bool? secondary, })

Implementation

static Iterable<Node>? tryCreateFootnoteLink(
  LinkContext context,
  String text, {
  bool? secondary,
}) {
  secondary ??= false;
  final parser = context.parser;
  final key = _footnoteLabel(text);
  final refs = parser.document.footnoteReferences;
  // `label` is what footnoteReferences stored, it is case sensitive.
  final label =
      refs.keys.firstWhere((k) => k.toLowerCase() == key, orElse: () => '');
  // `count != null` means footnote was valid.
  var count = refs[label];
  // And then check if footnote was matched.
  if (key == null || count == null) {
    return null;
  }
  final result = <Node>[];
  // There are 4 cases here: ![^...], [^...], ![...][^...], [...][^...]
  if (context.opener.char == $exclamation) {
    result.add(Text('!'));
  }
  refs[label] = ++count;
  final labels = parser.document.footnoteLabels;
  var pos = labels.indexOf(key);
  if (pos < 0) {
    pos = labels.length;
    labels.add(key);
  }

  // `children` are text segments after '[^' before ']'.
  final children = context.getChildren();
  if (secondary) {
    result.add(Text('['));
    result.addAll(children);
    result.add(Text(']'));
  }
  final id = Uri.encodeComponent(label);
  final suffix = count > 1 ? '-$count' : '';
  final link = Element('a', [Text('${pos + 1}')])
    // Ignore GitHub's attribute: <data-footnote-ref>.
    ..attributes['href'] = '#fn-$id'
    ..attributes['id'] = 'fnref-$id$suffix';
  final sup = Element('sup', [link])..attributes['class'] = 'footnote-ref';
  result.add(sup);
  return result;
}