InlineMd class abstract

Inline component of the legacy regex pipeline.

A subclass is reachable only through inlineComponents, which selects the legacy pipeline: the document is rendered as one text tree, with no incremental segment cache, no span-level streaming reveal and no lazy sliver, so a streaming reply re-parses and re-lays-out the whole message on every append. Use InlinePattern for host syntax that is still text, or InlineDirective for a delimited payload the parser must not read; both work on either pipeline.

Before:

class ShoutMd extends InlineMd {
  @override
  RegExp get exp => RegExp(r'!![A-Za-z]+!!');

  @override
  InlineSpan span(
    BuildContext context,
    String text,
    GptMarkdownConfig config,
  ) {
    return TextSpan(
      text: text.replaceAll('!!', '').toUpperCase(),
      style: config.style?.copyWith(fontWeight: FontWeight.bold),
    );
  }
}

GptMarkdown(
  text,
  inlineComponents: [ShoutMd(), ...MarkdownComponent.inlineComponents],
)

After:

GptMarkdown(
  text,
  inlinePatterns: [
    InlinePattern(
      pattern: RegExp(r'!![A-Za-z]+!!'),
      builder: (context, match, style) => TextSpan(
        text: match[0]!.replaceAll('!!', '').toUpperCase(),
        style: style.copyWith(fontWeight: FontWeight.bold),
      ),
    ),
  ],
)