backend/actions/existence.h

//
// Copyright 2020 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
//
//      http://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_CLOUD_SPANNER_EMULATOR_BACKEND_ACTIONS_EXISTENCE_H_
#define THIRD_PARTY_CLOUD_SPANNER_EMULATOR_BACKEND_ACTIONS_EXISTENCE_H_

#include "backend/actions/action.h"
#include "backend/actions/context.h"
#include "backend/actions/ops.h"
#include "absl/status/status.h"

namespace google {
namespace spanner {
namespace emulator {
namespace backend {

// RowExistenceValidator triggers on mutations to validate if current mutation
// will violate an already existing row.
//
// Delete operations do not need validation, though following validations
// are performed on Insert & Update operations:
// - Insert: Validates there is no existing row with the same key in this table.
// - Update: Validates there is an existing row with the same key in this table.
class RowExistenceValidator : public Validator {
 private:
  absl::Status Validate(const ActionContext* ctx,
                        const InsertOp& op) const override;
  absl::Status Validate(const ActionContext* ctx,
                        const UpdateOp& op) const override;
};

}  // namespace backend
}  // namespace emulator
}  // namespace spanner
}  // namespace google

#endif  // THIRD_PARTY_CLOUD_SPANNER_EMULATOR_BACKEND_ACTIONS_EXISTENCE_H_