private static function tokenize()

in src/inlines/Emphasis.php [75:166]
72 lines of code
12 McCabe index (conditional complexity)

  private static function tokenize(
     Context $context,
     string $markdown,
     int $initial_offset,
  ): ?vec<Stack\Node> {
    $offset = $initial_offset;
    if (!self::isStartOfRun($context, $markdown, $offset)) {
      return null;
    }

    // This is tricky as until we find the closing marker, we don't know if
    // `***` means:
    //  - `<strong><em>`
    //  - `<em><strong>`
    //  - `<em>**`
    //  - `<strong>*`
    //  - `***`

    $start = self::consumeDelimiterRun($markdown, $offset);
    list($start, $end_offset) = $start;
    if (!self::isLeftFlankingDelimiterRun($markdown, $offset, $end_offset)) {
      return null;
    }
    $stack = vec[
      new Stack\DelimiterNode(
        $start,
        self::IS_START,
        $offset,
        $end_offset,
      ),
    ];
    $offset = $end_offset;

    $text = '';

    // Tokenize into a stack of TextNodes, InlineNodes, and DelimiterNodes
    $len = Str\length($markdown);
    for (; $offset < $len; ++$offset) {
      $inline = self::consumeHigherPrecedence($context, $markdown, $offset);
      if ($inline !== null) {
        list($inline, $end_offset) = $inline;
        if ($text !== '') {
          // Leading plain text - *not* what we just matched
          $leading_end = $offset;
          $leading_start = $leading_end - Str\length($text);
          $stack[] = new Stack\TextNode($text, $leading_start, $leading_end);
          $text = '';
        }
        $stack[] = new Stack\InlineNode($inline, $offset, $end_offset);
        $offset = $end_offset - 1;
        continue;
      }

      if (self::isStartOfRun($context, $markdown, $offset)) {
        list($run, $end_offset) = self::consumeDelimiterRun($markdown, $offset);
        $flags = 0;

        if (self::isLeftFlankingDelimiterRun($markdown, $offset, $end_offset)) {
          $flags |= self::IS_START;
        }
        if (
          self::isRightFlankingDelimiterRun($markdown, $offset, $end_offset)
        ) {
          $flags |= self::IS_END;
        }

        if ($flags !== 0) {
          if ($text !== '') {
            // Leading plain text again, before the delimiter
            $leading_end = $offset;
            $leading_start = $leading_end - Str\length($text);
            $stack[] = new Stack\TextNode($text, $leading_start, $leading_end);
            $text = '';
          }
          $stack[] =
            new Stack\DelimiterNode($run, $flags, $offset, $end_offset);
          $offset = $end_offset - 1;
          continue;
        }
      }

      $text .= $markdown[$offset];
    }

    if ($text !== '') {
      $end_offset = $offset;
      $start_offset = $end_offset - Str\length($text);
      $stack[] = new Stack\TextNode($text, $start_offset, $end_offset);
    }

    return $stack;
  }