relativeIfContains method

String? relativeIfContains(String path)

Return a relative path if the path references a resource in this folder, or null if it doesn't.

The path must be absolute and normalized.

Implementation

String? relativeIfContains(String path) {
  // Given that paths are absolute and normalized the below is equivalent,
  // but much faster, than something like
  // ```
  // if (parent.contains(path)) {
  //  return provider.pathContext.relative(path, from: this.path);
  // }
  // return null;
  // ```
  String parent = this.path;
  if (path.length <= parent.length) return null;
  int separator = path.codeUnitAt(parent.length);
  var style = provider.pathContext.style;
  if (!style.isSeparator(separator)) return null;
  for (var i = 0; i < parent.length; i++) {
    if (parent.codeUnitAt(i) != path.codeUnitAt(i) &&
        !style.codeUnitsEqual(parent.codeUnitAt(i), path.codeUnitAt(i))) {
      return null;
    }
  }
  return path.substring(parent.length + 1);
}