writeConvertHtmlEntities static method

void writeConvertHtmlEntities(String input, StringBuffer target)

Writes the HTML entities such as & from the input into the target StringBuffer.

Implementation

static void writeConvertHtmlEntities(String input, StringBuffer target) {
  final matches = _htmlEntityRegex.allMatches(input);
  var lastStartIndex = 0;
  for (final match in matches) {
    if (match.start > lastStartIndex) {
      target.write(input.substring(lastStartIndex, match.start));
    }
    final entity = match.group(0)!;
    final replacement = _characters[entity];
    if (replacement != null) {
      target.write(replacement);
    } else {
      int? charCode;
      if (entity.startsWith('&#x')) {
        // this is a hexadecimal number:
        final hexText = entity.substring('&#x'.length, entity.length - 1);
        charCode = int.tryParse(hexText, radix: 16);
      } else if (entity.startsWith('&#')) {
        final text = entity.substring('&#'.length, entity.length - 1);
        charCode = int.tryParse(text);
      }
      if (charCode != null) {
        final charText = String.fromCharCode(charCode);
        target.write(charText);
      } else {
        print('Warning: unable to decode HTML entity "$entity"');
        target.write(entity);
      }
    }
    lastStartIndex = match.end;
  }
  if (lastStartIndex < input.length) {
    target.write(input.substring(lastStartIndex));
  }
}