spanForElement function Null safety

SourceSpan spanForElement(
  1. Element element,
  2. [SourceFile? file]
)

Returns a source span that spans the location where element is defined.

May be used to emit user-friendly warning and error messages:

void invalidClass(ClassElement class) {
  log.warning(spanForElement.message('Cannot implement "Secret"'));
}

Not all results from the analyzer API may return source information as part of the element, so file may need to be manually provided in those cases.

Implementation

SourceSpan spanForElement(Element element, [SourceFile? file]) {
  final url = assetToPackageUrl(element.source!.uri);
  if (file == null) {
    final contents = element.source?.contents;
    if (contents == null) {
      return SourceSpan(
        SourceLocation(
          element.nameOffset,
          sourceUrl: url,
        ),
        SourceLocation(
          element.nameOffset + element.nameLength,
          sourceUrl: url,
        ),
        element.name!,
      );
    }
    file = SourceFile.fromString(contents.data, url: url);
  }
  if (element.nameOffset < 0) {
    if (element is PropertyInducingElement) {
      if (element.getter != null) {
        return spanForElement(element.getter!);
      }

      if (element.setter != null) {
        return spanForElement(element.setter!);
      }
    }
  }

  return file.span(element.nameOffset, element.nameOffset + element.nameLength);
}