Class FunctionResult

base/function_result.h:27–58

Represents a function result that is unknown at the time of execution. This allows for lazy evaluation of expensive functions.

// Represents a function result that is unknown at the time of execution. This
// allows for lazy evaluation of expensive functions.
class FunctionResult final {
 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_;
};

inline bool operator==(const FunctionResult& lhs, const FunctionResult& rhs) {
  return lhs.IsEqualTo(rhs);