public:

FunctionResult() = delete;

FunctionResult(const FunctionResult&) = default;

FunctionResult(FunctionResult&&) = default;

FunctionResult& operator=(const FunctionResult&) = default;

FunctionResult& operator=(FunctionResult&&) = default;

FunctionResult(FunctionDescriptor descriptor, int64_t expr_id)

: descriptor_(std::move(descriptor)), expr_id_(expr_id) {}

// The descriptor of the called function that return Unknown.

const FunctionDescriptor& descriptor() const { return descriptor_; }

// The id of the |Expr| that triggered the function call step. Provided

// informationally -- if two different |Expr|s generate the same unknown call,

// they will be treated as the same unknown function result.

int64_t call_expr_id() const { return expr_id_; }

// Equality operator provided for testing. Compatible with set less-than

// comparator.

// Compares descriptor then arguments elementwise.

bool IsEqualTo(const FunctionResult& other) const {

return descriptor() == other.descriptor();

}

// TODO(uncreated-issue/5): re-implement argument capture

private:

FunctionDescriptor descriptor_;

int64_t expr_id_;