filter method

@override List<TreeReference> filter(DataInstance sourceInstance, TreeReference nodeset, XPathExpression predicate, List<TreeReference> children, EvaluationContext context, List<TreeReference> next(),)

The children of nodeset that pass predicate, or the result of next (the rest of the chain) when this strategy doesn't apply.

Implementation

@override
List<TreeReference> filter(
  DataInstance sourceInstance,
  TreeReference nodeset,
  XPathExpression predicate,
  List<TreeReference> children,
  EvaluationContext context,
  List<TreeReference> Function() next,
) {
  if (sourceInstance.instanceId == null || predicate is! XPathEqExpr) {
    return next();
  }
  final candidate = CompareToNodeExpression.parse(predicate);
  if (candidate == null || !predicate.equal) return next();
  final section = '$nodeset${candidate.nodeSide}';
  final sectionIndex = _index.putIfAbsent(section, () {
    final built = <String, List<TreeReference>>{};
    for (var i = 0; i < children.length; i++) {
      Measure.log('IndexEvaluation');
      final value = _javaToString(
        candidate.evalNodeSide(sourceInstance, context, children[i], i),
      );
      (built[value] ??= []).add(children[i]);
    }
    return built;
  });
  final absoluteValue = candidate.evalContextSide(sourceInstance, context);
  if (absoluteValue is! String) return next();
  return sectionIndex[absoluteValue] ?? const [];
}