excerpt static method

String? excerpt(String text, String phrase, { int radius = 100, String omission = '...', })

Extracts a snippet of text around the first occurrence of phrase.

radius is the number of characters to keep on either side. Returns null if phrase is not found.

Implementation

static String? excerpt(
  String text,
  String phrase, {
  int radius = 100,
  String omission = '...',
}) {
  if (phrase.isEmpty) return null;
  final i = text.indexOf(phrase);
  if (i == -1) return null;
  final start = (i - radius).clamp(0, text.length);
  final end = (i + phrase.length + radius).clamp(0, text.length);
  final snippet = text.substring(start, end);
  final prefix = start > 0 ? omission : '';
  final suffix = end < text.length ? omission : '';
  return '$prefix$snippet$suffix';
}