public:

AttributeUtility(

absl::Span<const cel::AttributePattern> unknown_patterns,

absl::Span<const cel::AttributePattern> missing_attribute_patterns,

cel::MemoryManager& manager)

: unknown_patterns_(unknown_patterns),

missing_attribute_patterns_(missing_attribute_patterns),

memory_manager_(manager) {}

AttributeUtility(const AttributeUtility&) = delete;

AttributeUtility& operator=(const AttributeUtility&) = delete;

AttributeUtility(AttributeUtility&&) = delete;

AttributeUtility& operator=(AttributeUtility&&) = delete;

// Checks whether particular corresponds to any patterns that define missing

// attribute.

bool CheckForMissingAttribute(const AttributeTrail& trail) const;

// Checks whether particular corresponds to any patterns that define unknowns.

bool CheckForUnknown(const AttributeTrail& trail, bool use_partial) const;

// Creates merged UnknownAttributeSet.

// Scans over the args collection, determines if there matches to unknown

// patterns and returns the (possibly empty) collection.

UnknownAttributeSet CheckForUnknowns(absl::Span<const AttributeTrail> args,

bool use_partial) const;

// Creates merged UnknownSet.

// Scans over the args collection, merges any UnknownAttributeSets found in

// it together with initial_set (if initial_set is not null).

// Returns pointer to merged set or nullptr, if there were no sets to merge.

const UnknownSet* MergeUnknowns(

absl::Span<const cel::Handle<cel::Value>> args,

const UnknownSet* initial_set) const;

// Creates merged UnknownSet.

// Merges together attributes from UnknownSets 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.

const UnknownSet* MergeUnknowns(

absl::Span<const cel::Handle<cel::Value>> args,

absl::Span<const AttributeTrail> attrs, const UnknownSet* initial_set,

bool use_partial) const;

// Create an initial UnknownSet from a single attribute.

const UnknownSet* CreateUnknownSet(cel::Attribute attr) const;

// Create an initial UnknownSet from a single missing function call.

const UnknownSet* CreateUnknownSet(

const cel::FunctionDescriptor& fn_descriptor, int64_t expr_id,

absl::Span<const cel::Handle<cel::Value>> args) const;

private:

absl::Span<const cel::AttributePattern> unknown_patterns_;

absl::Span<const cel::AttributePattern> missing_attribute_patterns_;

cel::MemoryManager& memory_manager_;