// Copyright 2022 Google LLC

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     https://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

#ifndef THIRD_PARTY_CEL_CPP_BASE_FUNCTION_RESULT_H_

#define THIRD_PARTY_CEL_CPP_BASE_FUNCTION_RESULT_H_

#include <cstdint>

#include <utility>

#include "base/function_descriptor.h"

namespace cel {

// 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);

}

inline bool operator<(const FunctionResult& lhs, const FunctionResult& rhs) {

  return lhs.descriptor() < rhs.descriptor();

}

}  // namespace cel

#endif  // THIRD_PARTY_CEL_CPP_BASE_FUNCTION_RESULT_H_