parseLiteDescriptors function

Map<String, List<FontVariant>> parseLiteDescriptors(String source)

The families and files in the source of google_fonts_lite.dart.

Throws if a family has missing, duplicate, or malformed variants.

Implementation

Map<String, List<FontVariant>> parseLiteDescriptors(String source) {
  final families = RegExp(
    r"^    '([^']+)': \{",
    multiLine: true,
  ).allMatches(source).toList();
  final variants = RegExp(
    r"GoogleFontsVariant\(\s*fontWeight: FontWeight\.w(\d+),\s*"
    r"fontStyle: FontStyle\.(normal|italic),\s*\): (?:const )?"
    r"GoogleFontsFile\(\s*'([0-9a-f]{64})',\s*(\d+),",
  );
  final result = <String, List<FontVariant>>{};
  for (var i = 0; i < families.length; i++) {
    final family = families[i].group(1)!;
    final block = source.substring(
      families[i].end,
      i + 1 == families.length ? source.length : families[i + 1].start,
    );
    final entries = variants
        .allMatches(block)
        .map(
          (match) => FontVariant(
            int.parse(match.group(1)!),
            match.group(2) == 'italic',
            match.group(3)!,
            int.parse(match.group(4)!),
          ),
        )
        .toList();
    if (entries.isEmpty ||
        entries.length !=
            RegExp(r'GoogleFontsVariant\(').allMatches(block).length ||
        result.containsKey(family) ||
        entries.map((entry) => entry.pickerName).toSet().length !=
            entries.length) {
      throw FormatException(
        'Missing, duplicate, or malformed variants: $family',
      );
    }
    result[family] = entries;
  }
  if (result.isEmpty) throw const FormatException('No Lite descriptors found');
  return result;
}