convertTagTextToInlineSpans<T> function

Future<List<InlineSpan>> convertTagTextToInlineSpans<T>(String text, { required List<TagStyle> tagStyles, required FutureOr<T?> backendToTaggable(String prefix, String backendString), required InlineSpan taggableToInlineSpan(T taggable, TagStyle tagStyle), })

A utility function that converts a tag text into a list of inline spans.

You can use this to convert a string containing tags (in the backend format) into a list of inline spans, where each tag is represented by a custom widget.

Typically, the tagStyles list is the same as the one used in the creation of the tag text to parse the tags. The backendToTaggable function is used to convert the backend string into a taggable object and may be asynchronous.

Usage:

return convertTagTextToInlineSpans<Taggable>(
  backendFormat,
  tagStyles: _controller.tagStyles,
  backendToTaggable: backendToTaggable,
  taggableToInlineSpan: (taggable, tagStyle) {
    return TextSpan(
      text: '${tagStyle.prefix}${taggable.name}',
      style: tagStyle.textStyle,
      recognizer: TapGestureRecognizer()
        ..onTap = () => ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(
                content: Text(
                  'Tapped ${taggable.name} with id ${taggable.id}',
                ),
                duration: const Duration(seconds: 2),
              ),
            ),
    );
  },
);

Implementation

Future<List<InlineSpan>> convertTagTextToInlineSpans<T>(
  String text, {
  required List<TagStyle> tagStyles,
  required FutureOr<T?> Function(String prefix, String backendString)
      backendToTaggable,
  required InlineSpan Function(T taggable, TagStyle tagStyle)
      taggableToInlineSpan,
}) async {
  final pattern = tagStyles
      .map((style) => '${RegExp.escape(style.prefix)}(${style.regExp})')
      .join('|');
  final spans = <InlineSpan>[];
  int position = 0;

  for (final match in RegExp(pattern).allMatches(text)) {
    final textBeforeTag = text.substring(position, match.start);
    spans.add(TextSpan(text: textBeforeTag));
    position = match.end;

    final tagStyle = tagStyles.firstWhere(
      (style) => match.group(0)!.startsWith(style.prefix),
    );
    final taggable = await backendToTaggable(
      tagStyle.prefix,
      match.group(0)!.substring(tagStyle.prefix.length),
    );

    if (taggable != null) {
      spans.add(taggableToInlineSpan(taggable, tagStyle));
    } else {
      spans.add(TextSpan(text: match.group(0)));
    }
  }
  if (text.substring(position).isNotEmpty) {
    spans.add(TextSpan(text: text.substring(position)));
  }
  return spans;
}