Method IdentifyAndMergeUnknowns

eval/eval/attribute_utility.cc:172–200

Creates merged UnknownAttributeSet. Merges together attributes from UnknownAttributeSets found in the args collection, attributes from attr that match unknown pattern patterns, and attributes from initial_set (if initial_set is not null). Returns pointer to merged set or nullptr, if there were no sets to merge.

// (if initial_set is not null).
// Returns pointer to merged set or nullptr, if there were no sets to merge.
absl::optional<UnknownValue> AttributeUtility::IdentifyAndMergeUnknowns(
    absl::Span<const cel::Value> args, absl::Span<const AttributeTrail> attrs,
    bool use_partial) const {
  absl::optional<UnknownSet> result_set;

  // Identify new unknowns by attribute patterns.
  cel::AttributeSet attr_set = CheckForUnknowns(attrs, use_partial);
  if (!attr_set.empty()) {
    result_set.emplace(std::move(attr_set));
  }

  // merge down existing unknown sets
  absl::optional<UnknownValue> arg_unknowns = MergeUnknowns(args);

  if (!result_set.has_value()) {
    // No new unknowns so no need to check for presence of existing unknowns --
    // just forward.
    return arg_unknowns;
  }

  if (arg_unknowns.has_value()) {
    cel::base_internal::UnknownSetAccess::Add(
        *result_set, UnknownSet((*arg_unknowns).attribute_set(),
                                (*arg_unknowns).function_result_set()));
  }

  return UnknownValue(cel::Unknown(result_set->unknown_attributes(),
                                   result_set->unknown_function_results()));
}

UnknownValue AttributeUtility::CreateUnknownSet(cel::Attribute attr) const {
  return UnknownValue(cel::Unknown(AttributeSet({std::move(attr)})));