Class AttributePattern

base/attribute.h:221–267

AttributePattern is a fully-qualified absolute attribute path pattern. Supported segments steps in the path are: - field selection; - map lookup by key; - list access by index.

// - map lookup by key;
// - list access by index.
class AttributePattern final {
 public:
  // MatchType enum specifies how closely pattern is matching the attribute:
  enum class MatchType {
    NONE,     // Pattern does not match attribute itself nor its children
    PARTIAL,  // Pattern matches an entity nested within attribute;
    FULL      // Pattern matches an attribute itself.
  };

  AttributePattern(std::string variable,
                   std::vector<AttributeQualifierPattern> qualifier_path)
      : variable_(std::move(variable)),
        qualifier_path_(std::move(qualifier_path)) {}

  absl::string_view variable() const { return variable_; }

  absl::Span<const AttributeQualifierPattern> qualifier_path() const {
    return qualifier_path_;
  }

  // Matches the pattern to an attribute.
  // Distinguishes between no-match, partial match and full match cases.
  MatchType IsMatch(const Attribute& attribute) const {
    MatchType result = MatchType::NONE;
    if (attribute.variable_name() != variable_) {
      return result;
    }

    auto max_index = qualifier_path().size();
    result = MatchType::FULL;
    if (qualifier_path().size() > attribute.qualifier_path().size()) {
      max_index = attribute.qualifier_path().size();
      result = MatchType::PARTIAL;
    }

    for (size_t i = 0; i < max_index; i++) {
      if (!(qualifier_path()[i].IsMatch(attribute.qualifier_path()[i]))) {
        return MatchType::NONE;
      }
    }
    return result;
  }

 private:
  std::string variable_;
  std::vector<AttributeQualifierPattern> qualifier_path_;
};

struct FieldSpecifier {
  int64_t number;